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NEUROSURGERY

October 1996
Vol. 39, No. 4

Abstracts

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The History of Spinal Biomechanics

Abhay Sanan, M.D., Setti S. Rengachary, M.D.

Department of Neurosurgery, University of Minnesota Hospital System,
Minneapolis, Minnesota

The history of spinal biomechanics has its origins in antiquity. The Edwin
Smith surgical papyrus, an Egyptian document written in the 17th century BC,
described the difference between cervical sprain, fracture, and
fracture-dislocation. By the time of Hippocrates (4th century BC), physical
means such as traction or local pressure were being used to correct spinal
deformities but the treatments were based on only a rudimentary knowledge of
spinal biomechanics. The Renaissance produced the first serious attempts at
understanding spinal biomechanics. Leonardo da Vinci (14521519) accurately
described the anatomy of the spine and was perhaps the first to investigate
spinal stability. The first comprehensive treatise on biomechanics, De Motu
Animalium, was published by Giovanni Borelli in 1680, and it contained the
first analysis of weight bearing by the spine. In this regard, Borelli can
be considered the "Father of Spinal Biomechanics." By the end of the 19th
century, the basic biomechanical concepts of spinal alignment and
immobilization were well entrenched as therapies for spinal cord injury.
Further anatomic delineation of spinal stability was sparked by the anatomic
analyses of judicial hangings by Wood-Jones in 1913. By the 1960s, a
two-column model of the spine was proposed by Holdsworth. The modern concept
of Denis' three-column model of the spine is supported by more sophisticated
testing of cadaver spines in modern biomechanical laboratories. The modern
explosion of spinal instrumentation stems from a deeper understanding of the
load-bearing structures of the spinal column.
(Neurosurgery, 39:657669, 1996)

Key words: Biomechanics, Borelli, Hanging, Hippocrates, History, Spinal
devices, Spinal injury, Spine




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Complications Resulting from Saphenous Vein Patch Graft after Carotid
Endarterectomy

Yoshihiro Yamamoto, M.D., David G. Piepgras, M.D., W. Richard Marsh, M.D.,
Fredric B. Meyer, M.D.

Department of Neurological Surgery, Mayo Clinic and Mayo Foundation,
Rochester, Minnesota

OBJECTIVE: Reducing surgical risks to the minimum in carotid endarterectomy
has become crucial, especially with the results of recent clinical trials
extending indications to asymptomatic patients. The use of the saphenous
vein patch graft (SVPG) has been suggested to reduce early postoperative
thrombosis and cerebral infarct as well as late recurrent stenosis. However,
the exact risks and complications involved in this technique are not known.

METHODS: During a 23-year period (19721994), 2888 carotid endarterectomies
with SVPG for primary carotid stenosis were performed by the Neurosurgical
Cerebrovascular Service at the Mayo Clinic. The data from all patients were
retrospectively analyzed, emphasizing postoperative complications related to
SVPG.

RESULTS: There were five postoperative vein ruptures (0.17%), four cases of
aneurysm formation, and three cases of deep infection necessitating surgical
intervention. The vein patch ruptured in one male patient and four female
patients (mean age, 69 yr). All ruptures occurred within 4 days of the
primary operation, including two during the first 24 hours. All patients
with rupture underwent emergency surgery and were found to have intact
suture lines and tears in the middle of the grafts. Two patients recovered
without deficits, one suffered major disability, and the other two died.
Aneurysm of the patch developed in two male patients and two female patients
(mean age, 71 yr). All of the patients developed painless pulsatile neck
masses 1 to 9 years after the initial surgery; two also had recurrent
ischemic symptoms. All of the patients with aneurysms underwent surgical
correction without consequences.

CONCLUSION: Although the benefit of routine use of SVPG in carotid
endarterectomy is still the focus of debate, this analysis showed that its
use adds a small but definite risk of serious complications related to
inherent weakness of the venous tissue. If a surgeon chooses to use a patch
graft, our recommendation is for use of a synthetic material rather than
vein.
(Neurosurgery 39:670676, 1996)

Key words: Carotid aneurysm, Carotid endarterectomy, Collagen-impregnated
dacron, Saphenous vein patch graft, Vein patch rupture




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Occult Cerebrovascular Malformations after Irradiation

Eugenio Pozzati, M.D., Felice Giangaspero, M.D., Federica Marliani, M.D.,
Nicola Acciarri, M.D.

Department of Neurosurgery and Services of Pathology and Neuroradiology,
Bellaria Hospital, Bologna, Italy

OBJECTIVE: It has recently been found that patients receiving cerebral
irradiation can develop hemorrhagic dysangiogeneses simulating occult
vascular malformations. To analyze this connection, we report on five
patients with occult cerebrovascular malformations occurring after
"standard" or focused irradiation performed for brain tumors in four
patients and for a deep-seated cavernous angioma in one patient.

METHODS: All lesions were within the radiation ports. The time interval
between irradiation and the detection of the occult vascular malformations
varied from 3 to 9 years; the ratio of female to male patients was 4:1. Four
patients were <15 years old when first irradiated. Four patients presented
with acute symptoms (headache, vomiting, focal signs) and one was
asymptomatic when the lesions were first detected. Serial magnetic resonance
imaging scans were available in four patients and a computed tomographic
scan in the other patient.

RESULTS: The initial appearance was that of a hypointense T1T2 focus;
magnetic resonance imaging then revealed focal or multifocal T1
hyperintensity and T2 mixed signal intensity followed by a late ring of
decreased signal intensity. Four patients were operated on and one was under
neuroradiological monitoring. Histological features of these lesions
included clusters of closely packed vascular spaces resembling cavernous
malformations sometimes associated with a thrombosed thick-walled vein with
intense hemosiderin deposition and fibroblastic proliferation;
telangiectasic changes were also seen in the adjacent brain.

CONCLUSION: Increased awareness of occult cerebrovascular malformations is
necessary, because their occurrence is not infrequent and they have
hemorrhagic potential. Children receiving cerebral irradiation are at
greater risk of this complication.
(Neurosurgery 39:677684, 1996)

Key words: Cavernous angioma, Hemorrhage, Infancy, Magnetic resonance
imaging, Occult vascular malformation, Radiation therapy




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Intracranial Aneurysms and Cervicocephalic Arterial Dissections Associated
with Congenital Heart Disease

Wouter I. Schievink, M.D., Bahram Mokri, M.D., David G. Piepgras, M.D.,
Adriana C. Gittenberger-de Groot, Ph.D.

Departments of Neurologic Surgery (WIS, DGP) and Neurology (BM), Mayo
Clinic, Rochester, Minnesota, and Department of Anatomy and Embryology
(ACG-dG), University of Leiden, Leiden, The Netherlands

OBJECTIVE: The number of patients with congenital heart disease who survive
to adolescence and adulthood continues to increase. We review our experience
with noninfectious intracranial aneurysms and cervicocephalic arterial
dissections in patients with congenital heart disease, expanding the
clinical spectrum of the cerebrovascular abnormalities that may be
encountered in this group of patients.

METHODS: All patients with congenital heart disease and intracranial
aneurysms or cervicocephalic arterial dissections, who were evaluated at the
Mayo Clinic between 1969 and 1992, were identified.

RESULTS: Congenital heart disease was diagnosed in 3 (8%) of 36 children
with intracranial aneurysms, in 5 (0.3%) of 1994 adults with intracranial
aneurysms, in 1 (4%) of 25 children with cervicocephalic arterial
dissections, and in 5 (2%) of 250 adults with cervicocephalic arterial
dissections. The mean age of the 14 patients was 32 years (range, 1358 yr).
The congenital heart disorders consisted of complex cardiac anomalies in
three patients (truncus arteriosus, transposition of the great arteries, and
tricuspid atresia in one patient each), pulmonic valve or arterial stenosis
in two patients, aortic coarctation in four patients, and bicuspid aortic
valve in five patients. Only one patient had an intracranial aneurysm and
coarctation of the aorta.

CONCLUSION: Individuals with a variety of congenital heart disorders may be
at an increased risk of intracranial aneurysm development and
cervicocephalic arterial dissection, particularly in adolescence. The
muscular arteries of the head and neck are derived from neural crest cells
and the neural crest is also of major importance in early cardiac
development, suggesting that an abnormality of the neural crest may be the
common pathogenetic factor explaining this association.
(Neurosurgery 39:685690, 1996)

Key words: Aneurysm, dissecting; Cerebral aneurysm; Cerebrovascular disease;
Coarctation of the aorta; Congenital heart disease; Neural crest




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The Beaten Copper Cranium: A Correlation between Intracranial Pressure,
Cranial Radiographs, and Computed Tomographic Scans in Children with
Craniosynostosis

Gerald F. Tuite, M.D., Jane Evanson, F.R.C.R., W.K. Chong, M.D., Dominic
N.P. Thompson, F.R.C.S., William F. Harkness, F.R.C.S., Barry M. Jones,
F.R.C.S., Richard D. Hayward, F.R.C.S.

The Craniofacial Unit (GFT, DNPT, WFH, BMJ, RDH) and Department of Radiology
(JE, WKC), Great Ormond Street Hospital for Children, London, England

OBJECTIVE: The beaten copper appearance of the cranium, as well as other
cranial radiographic and computed tomographic findings in children with
craniosynostosis, is often interpreted by clinicians as evidence of elevated
intracranial pressure (ICP). However, a correlation between radiological
findings and ICP measurements has not been previously demonstrated, and
their usefulness in detecting elevated ICP has not been defined.

METHODS: To address those issues, 123 children with craniosynostosis who had
cranial radiographs and ICP monitoring were studied. To assess the
specificity of certain radiological findings to patients with
craniosynostosis, cranial radiographs of patients with craniosynostosis were
compared to those of age- and sex-matched controls. In patients with
craniosynostosis, findings on cranial radiographs were compared to computed
tomographic scans of the brain. Radiographic findings were then correlated
with ICP measurements obtained while the patient was sleeping, which was
measured using a Camino fiberoptic ICP monitor (Camino Laboratories, San
Diego, CA). All radiographs were independently analyzed by two radiologists
who were blinded to clinical and ICP data.

RESULTS: A diffuse beaten copper pattern, erosion of the dorsum sella, and
suture diastasis were seen more commonly in patients with craniosynostosis
than in controls (P < 0.05), but the presence of the beaten copper pattern
was no more common in children with craniosynostosis. ICP was greater when a
diffuse beaten copper pattern, dorsum sellar erosion, suture diastasis, or
narrowing of basal cisterns was present (P < 0.05).

CONCLUSION: Although this study demonstrates that some cranial radiographic
and computed tomographic findings do correlate with elevated ICP, the
sensitivity of radiological methods for detecting elevated ICP is
universally low and they are not recommended to screen for elevated ICP in
children with craniosynostosis.
(Neurosurgery 39:691699, 1996)

Key words: Computed tomography, Craniosynostosis, Cranium, Hydrocephalus,
Intracranial pressure, Lckenschdel




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Pericytosis and Edema Generation: A Unique Clinicopathological Variant of
Meningioma

James C. Robinson, M.D., Venkat R. Challa, M.D., David S. Jones, M.D., David
L. Kelly, Jr., M.D.

Departments of Neurosurgery (JCR, VRC, DSJ, DLK) and Pathology (VRC), Wake
Forest University, Bowman Gray School of Medicine, Winston-Salem, North
Carolina

OBJECTIVE: We report a group of eight patients with a distinctive
histological variant of meningioma that is associated with severe
peritumoral edema. The clinical presentation, radiographic findings, and
histology of this type of tumor may lead to misdiagnosis as an aggressive or
malignant process.

METHODS: We reviewed the histology from patients who had removal of
meningiomas performed in our institution between 1978 and 1992. Tumors
having abnormal proliferation of cells in the intramural vascular spaces
were selected for study; case histories and radiographs were reviewed. Tumor
material was subjected to special stains, immunocytochemical examination,
and electron microscopy.

RESULTS: Several lesions were misread radiographically as being malignant.
Patients underwent craniotomy with complete excision of the tumor. All
lesions were small (3 cm), and no brain invasion, unusual tumor
vascularity, or dural sinus involvement was noted in any case.
Histologically, the meningioma pattern in each case was meningothelial and
benign in appearance. The immunocytochemical and electron microscopic
features of the unusual cells in the blood vessel walls are most consistent
with their being of pericytic origin. All patients have remained
asymptomatic and without evidence of tumor recurrence with follow-up from 3
to 12 years.

CONCLUSION: These tumors showed proliferation of pericytes in blood vessel
walls and represent a new subtype of meningothelial meningioma. The
apparently benign nature of these lesions necessitates their recognition.
Characteristic findings of pericytic proliferation associated with edema
generation have led us to descriptively term this the PEG variant of
meningioma.
(Neurosurgery 39:700707, 1996)

Key words: Cerebral edema, Meningioma, Pericyte




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Computed Tomographic Criteria and Survival Rate for Patients with Acute
Subdural Hematoma

Matthias Zumkeller, M.D., Renate Behrmann, M.D., Hans Egmont Heissler, Dipl.
-Ing., Herrmann Dietz, M.D.

Neurochirurgische Klinik, Medizinische Hochschule, Hannover, Germany

OBJECTIVE: Computed tomographic data from 174 patients with acute subdural
hematoma were analyzed statistically to identify parameters that could be
evaluated independently of clinical and neurological status to estimate
outcome.

METHODS: This retrospective study was made necessary by the fact that the
patients admitted usually had been treated with intubation, sedation, and
artificial ventilation, which precludes neurological examination.

RESULTS: In surgically treated patients, the hematoma thickness ranged from
5 to 35 mm and the midline shift was 0 to 33 mm. In 81 patients (46.6%), the
hematoma thickness was greater than the midline shift; in 24 patients
(13.8%), the hematoma thickness equaled the midline shift; and in 69
patients (39.6%), the midline shift exceeded the hematoma thickness. Of the
patients, 52% died after surgery, for 29% we obtained good or satisfying
results, and 19% were in poor condition after therapy. The Kaplan-Meier
survival analysis proved that the survival rate was only 50% for a hematoma
thickness of approximately 18 mm and a midline shift of 20 mm. The survival
function dropped markedly for midline shifts of more than 20 mm and
converged to 0% for midline shifts of more than 25 mm. If the midline shift
exceeded the hematoma thickness by 3 mm, the survival function was 50%; when
the midline shift exceeded the hematoma thickness by 5 mm, the survival
function was 25%. The Glasgow Outcome Scale scores were correlated
significantly with these parameters. The parameters, which are the measured
hematoma thickness, the midline shift, and the difference between the
hematoma thickness and the midline shift, allow robust/adequate estimation
of survival function and outcome for patients suffering from acute subdural
hematoma.

CONCLUSION: Based on these data, indications for surgery could be assessed
by means of video conferencing, i.e., without personal examination of the
patients.
(Neurosurgery 39:708713, 1996)

Key words: Acute subdural hematoma, Coma scale, Computed tomography, Head
injury, Midline shift




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Early Effects of Mannitol in Patients with Head Injuries Assessed Using
Bedside Multimodality Monitoring

Peter J. Kirkpatrick, F.R.C.S.(S.N.), Piotr Smielewski, M.Sc., Stefan
Piechnik, M.Sc., John D. Pickard, M.Chir., Marek Czosnyka, Ph.D.

Academic Department of Neurosurgery, Addenbrookes Hospital, Cambridge,
England

OBJECTIVE: We have employed bedside multimodality methods to assess the
influence of a slow (20 min) bolus of hypertonic mannitol on cerebral
hemodynamics in comatose patients with head injuries.

METHODS: Middle cerebral artery flow velocities (FV) and cortical
microcirculatory flows were measured in comatose patients with head injuries
after the administration of 200 ml of 20% mannitol. A comparison was made
with the effects of an identical bolus of isotonic saline. Fourteen patients
with diffuse head injuries and with raised intracranial pressure were
selected, and mannitol infusion studies were conducted when clinically
indicated (n = 23). Using transcranial doppler and laser doppler flowmetry
(LDF), indices of estimated cerebrovascular resistance (eCVR) were
calculated for the macro- (eCVR-FV) and micro- (eCVR-LDF) circulation.

RESULTS: During mannitol infusion, a significant rise in cerebral perfusion
pressure was detected (+10%, P = 0.03) as a result of a fall in intracranial
pressure (-21%, P = 0.001). Increases in both FV (+13%, P < 0.001) and LDF
(+14%, P = 0.002) occurred only after the administration of mannitol and
persisted beyond completion of infusion. The effect on FV and LDF decayed
exponentially, with a time constant of 34.0 and 38.0 minutes, respectively,
and was independent of the pressure autoregulatory status. There was a
tendency for eCVR-FV and eCVR-LDF to decrease. No significant effects
resulted from the administration of saline.

CONCLUSION: Bedside multimodality monitoring may provide a useful means for
assessing the effects of therapy in the comatose patient. The mechanisms by
which mannitol reduces intracranial pressure in patients with head injuries
are discussed.
(Neurosurgery 39:714721, 1996)

Key words: Cerebral hemodynamics, Cerebrovascular resistance, Head injury,
LDF, Mannitol, TCD




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Hydrocephalus and Epilepsy: An Actuarial Analysis

Joseph H. Piatt, Jr., M.D., Christina Vert Carlson, B.A., B.S., R.N.

Department of Surgery (Neurosurgery) and Pediatrics, Oregon Health Sciences
University, Portland, Oregon

OBJECTIVE: To determine the prevalence of epilepsy among patients with
hydrocephalus and to identify risk factors.

METHODS: Retrospective chart review at a single institution was conducted.
The definition of epilepsy used was long-term administration of
antiepileptic drugs (AEDs) for suppression of seizures. Actuarial
methodology was used, with initiation of AED therapy as the endpoint of the
analysis.

RESULTS: Insertion or revision of cerebrospinal fluid (CSF) shunts was
performed on 464 patients at the study institution from 1976 through 1989.
At the time of initial CSF shunt insertion, 12% of patients had already been
treated with AEDs. After the 2nd year, the hazard rate for initiation of AED
treatment was a constant 2% per year, and by 10 years after initial shunt
insertion the estimated prevalence of AED treatment had risen to 33%. The
cause of the hydrocephalus was a strong determinant of the prevalence of AED
treatment, but most of the statistical effect of the cause was already
manifest at the time of initial CSF shunt insertion. Age of patient at
diagnosis of hydrocephalus, burr hole site, number of CSF shunt operations
during follow-up, and history of shunt infection were factors that had no
detectable association with AED treatment.

CONCLUSION: Epilepsy is common among patients with hydrocephalus, and the
risk of the development of epilepsy continues indefinitely for those
patients. The complications of CSF shunt surgery seem to play a relatively
minor role in the development of epilepsy in this patient population.
(Neurosurgery 39:722728, 1996)

Key words: Antiepileptic drug, Cerebrospinal fluid shunt, Epilepsy,
Hydrocephalus, Myelomeningocele, Seizure




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The Contralateral Transcallosal Approach: Experience with 32 Patients

Michael T. Lawton, M.D., John G. Golfinos, M.D., Robert F. Spetzler, M.D.

Division of Neurological Surgery, Barrow Neurological Institute, St.
Joseph's Hospital and Medical Center, Phoenix, Arizona

OBJECTIVE: To demonstrate the usefulness of the contralateral transcallosal
approach for resecting lesions located laterally in or adjacent to the
lateral ventricle.

METHODS: Modifications to the standard ipsilateral transcallosal technique
include positioning the head with the midline oriented horizontally, placing
the side with the lesion up, and performing the craniotomy and
interhemispheric dissection on the contralateral side. This approach avoids
a transcortical incision, allows gravity to hold open the interhemispheric
fissure, and increases the lateral exposure of the lesion. This approach was
used in 32 patients with a variety of lesions, including 6 cavernous
malformations, 7 arteriovenous malformations, and 19 tumors of various
types. All but three lesions were located on the left side.

RESULTS: All six cavernous malformations, all four benign tumors, and four
of the seven arteriovenous malformations were resected completely. Malignant
tumors were resected subtotally, and three arteriovenous malformations
required stereotactic radiosurgery to treat residual deep nidus. There was
no surgical mortality. Two patients experienced neurological deterioration.

CONCLUSION: The contralateral transcallosal approach can be used to treat a
variety of lesions safely and successfully.
(Neurosurgery 39:729735, 1996)

Key words: Arteriovenous malformations, Cavernous malformations,
Contralateral, Surgical technique, Transcallosal approach, Tumor




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Transfacial Transclival Approach for Midline Posterior Circulation Aneurysms

Christopher S. Ogilvy, M.D., Fred G. Barker II, M.D., Michael P. Joseph,
M.D., Mack L. Cheney, M.D., Brooke Swearingen, M.D., Robert M. Crowell, M.D.

Cerebrovascular Surgery, Neurosurgical Service, Massachusetts General
Hospital (CSO, FGB, BS) and Department of Otolaryngology, Massachusetts Eye
and Ear Infirmary (MPJ, MLC), Boston, Massachusetts, and The Berkshire
Medical Center, Pittsfield, Massachusetts (RMC)

OBJECTIVE: To evaluate the use of an anterior, transfacial transclival
approach to midline posterior circulation aneurysms in five patients.

SURGICAL APPROACH: A skin incision is made on the right side of the nose
with subsequent bony and cartilaginous disarticulation of the nasal complex.
The nose remains attached along the left side and is reflected laterally.
Removal of the nasal septum and bilateral ethmoidectomy, medial maxillectomy
(usually bilateral), and opening of the sphenoid yield a large triangular
exposure of the anterior clivus. After removal of the clivus with a drill,
the vertebral and basilar arteries are exposed through a midline dural
opening.

RESULTS: The approach provided excellent exposure of basilar artery trunk
aneurysms with room available for temporary clip placement in three
patients. In a fourth patient, a midline posterior inferior cerebellar
artery aneurysm was clipped using this technique. A basilar trunk dissection
was treated by proximal basilar occlusion through this exposure in a fifth
patient. Although three patients developed transient cerebrospinal fluid
leaks with symptoms of meningitis, no permanent neurological morbidity
resulted from the use of the approach.

CONCLUSION: The transfacial transclival approach to midline aneurysms of the
basilar trunk and its branches provided excellent exposure for surgical
treatment in five patients. No patient had postoperative palatal dysfunction
and cosmetic results were excellent. Cerebrospinal fluid leak and meningitis
continue to be the major drawbacks to the use of this approach, although the
availability of modern broad-spectrum antibiotics lessens the chance of
permanent neurological sequelae.
(Neurosurgery 39:736742, 1996)

Key words: Basilar artery, Clivus, Pedicled rhinotomy, Posterior circulation
aneurysm, Transclival transfacial approach, Vertebral artery




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Endoscopic Closure of Postsurgical Anterior Cranial Fossa Cerebrospinal
Fluid Leaks

Timothy F. Kelley, M.D., James A. Stankiewicz, M.D., James M. Chow, M.D.,
Thomas C. Origitano, M.D., John Shea, M.D.

Department of Otolaryngology, Head and Neck Surgery, University of
California, Irvine Medical Center, Orange, California (TFK), and Department
of Otolaryngology, Head and Neck Surgery, the Loyola Sinus Surgery Center
(JAS, JMC), and Department of Neurosurgery, Loyola University Medical Center
(TCO, JS), Maywood, Illinois

OBJECTIVE: The primary objective of this study is to present an alternative
technique to closure of anterior cranial fossa cerebrospinal fluid (CSF)
leaks. This study also serves to review our experience with our technique
and presents some technical "tricks" we have learned through experience.

METHODS: The design of this study is a clinical chart review. The setting is
an academic medical center.

RESULTS: Eight patients were referred for closure of postsurgical CSF leaks.
Seven of eight patients underwent closure with one attempt and closure was
achieved after a second attempt in one patient. Follow-up ranged from 1.5 to
4.0 years. There were no complications. No patient developed an acute or
delayed episode of meningitis.

CONCLUSION: The technique of endoscopic closure of a CSF leak is a safe and
effective means for closure of a postsurgical anterior cranial fossa CSF
fistula when performed by an experienced operator.
(Neurosurgery 39:743746, 1996)

Key words: Anterior cranial fossa, Cerebrospinal fluid leak, Endoscopic,
Fistula, Treatment




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Acrylic Cranioplasty Using Miniplate Struts

Robert E. Replogle, M.D., Giuseppe Lanzino, M.D., Paul Francel, M.D., Ph.D.,
Scott Henson, M.D., Kant Lin, M.D., John A. Jane, M.D., Ph.D.

Departments of Neurological Surgery (RER, GL, PF, JAJ) and Plastic Surgery
(KL), University of Virginia, Charlottesville, Virginia, and Division of
Neurosurgery, Albany Medical College, Albany, New York (SH)

OBJECTIVE: Cranioplasty using acrylic is a common procedure in patients with
cranial defects secondary to trauma, infection, or tumor. The limitations of
this technique include poor adherence of the acrylic to surrounding bone and
difficulty in achieving a proper cosmetic contour in complicated cranial
defects, especially those involving the orbital rim. The authors have been
continually developing techniques of cranioplasty.

METHODS: Ten consecutive cranioplasties were performed over the past 5 years
using this new technique.

TECHNIQUE: The authors describe a technique using miniplates as struts to
which the acrylic is applied using a "reinforced concrete" principle.

RESULTS/CONCLUSION: All patients achieved excellent cosmetic results with no
complications. This technique allows contour of the repair site while the
acrylic is curing and provides a more resilient resulting prosthesis.
(Neurosurgery 39:747749, 1996)

Key words: Cranial defect, Cranioplasty, Orbital rim defect




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Magnetic Resonance Neurography of Peripheral Nerve Lesions in the Lower
Extremity

Charles Kuntz IV, M.D., Lindsey Blake, M.D., Gavin Britz, M.D., Aaron
Filler, M.D., Ph.D., Cecil E. Hayes, Ph.D., Robert Goodkin, M.D., Jay
Tsuruda, M.D., Ken Maravilla, M.D., Michel Kliot, M.D.

Departments of Neurological Surgery (CK, GB, RG, MK) and Radiology (LB, CEH,
KM), University of Washington and Seattle Veterans Administration Medical
Center, Seattle, Washington; Division of Neurological Surgery, University of
California, Los Angeles Medical Center, Los Angeles, California (AF); and
Department of Radiology, University of Utah School of Medicine, Salt Lake
City, Utah (JT)

OBJECTIVE: We describe the clinical application and utility of
high-resolution magnetic resonance neurography (MRN) techniques to image the
normal fascicular structure of peripheral nerves and its distortion by mass
lesions or trauma in the lower extremity.

METHODS: MRN images were obtained using a standard 1.5 Tesla magnet and
custom built phased-array coils. Patients were imaged using T1-weighted spin
echo without and with gadolinium, T2-weighted fast spin echo with fat
suppression, and short tau inversion recovery fast spin-echo pulse
sequences. Nine patients were studied, four with peripheral nerve tumors
(three neurofibromas and one schwannoma), two with intraneural cysts, and
three with traumatic peripheral nerve lesions. Six patients with peripheral
nerve mass lesions underwent surgery, thereby allowing MRN images to be
correlated with intraoperative and pathological findings.

RESULTS: Preoperative MRN accurately imaged the normal fascicular anatomy of
peripheral nerves and precisely depicted its relation to tumor and cystic
lesions. Increased signal on T2-weighted fast spin-echo and short tau
inversion recovery fast spin-echo pulse sequences was seen in the peripheral
nerve fascicles of patients with clinical and electrodiagnostic evidence of
nerve injury.

CONCLUSION: MRN proved useful in the preoperative evaluation and planning of
surgery in patients with peripheral nerve lesions.
(Neurosurgery 39:750757, 1996)

Key words: Cyst, Magnetic resonance imaging, Neurofibroma, Neuropathy,
Peripheral nerve, Schwannoma, Trauma, Tumor




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Evaluation of Hydrocephalic Periventricular Radiolucency by Dynamic Computed
Tomography and Xenon-Computed Tomography

Hideki Nakano, M.D., Kuniaki Bandoh, M.D., Makoto Miyaoka, M.D., Kiyosi
Sato, M.D.

Department of Neurosurgery, Fujisawa City Hospital, Fujisawa City, Kanagawa,
(HN, KB, MM), and Department of Neurosurgery, Juntendou School of Medicine
(KS), Tokyo, Japan

OBJECTIVE: A common finding of computed tomography in a case of
normal-pressure hydrocephalus (NPH) is periventricular radiolucency (PVL).
We analyzed PVL for patients with hydrocephalus, using dynamic computed
tomographic and xenon-computed tomographic techniques to differentiate NPH
from similar diseases.

METHODS: Dynamic computed tomography was evaluated as a method of diagnosing
NPH in 14 patients with computed tomographic findings of both PVL and
ventricular dilatation. Of the 14 patients, varying degrees of clinical
improvement after shunt surgery were observed in 10 (shunt-effective group)
but not in the remaining 4 (shunt-ineffective group). The difference in
arrival time between PVL and thalamus, the difference in peak time between
PVL and anterior cerebral artery, and cerebral blood flow in PVL by
xenon-computed tomographic study were analyzed.

RESULTS: The difference in arrival time between PVL and thalamus was
significantly longer in the effective group than among the remaining
patients. There was no significant difference in PVL/cerebral blood flow and
the difference in peak time between PVL and the anterior cerebral artery
between the two groups.

CONCLUSION: Dynamic computed tomographic analysis of the difference in
arrival time between PVL and thalamus is useful for diagnosing NPH and
predicting response to shunting.
(Neurosurgery 39:758763, 1996)

Key words: Dynamic computed tomography, Normal pressure hydrocephalus,
Periventricular radiolucency, Xenon-computed tomography




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Bovine Pericardium for Dural Grafts: Clinical Results in 35 Patients

John A. Anson, M.D., Erich P. Marchand, M.D.

Division of Neurosurgery, University of New Mexico School of Medicine,
Albuquerque, New Mexico

OBJECTIVE: The United States Food and Drug Administration has recently
approved the marketing of bovine pericardium as a dural graft material, but
literature reports of this use are limited. Bovine pericardium has been
widely used for grafts in cardiac surgery and seems to have suitable
properties for use as a dural graft. We report the use of
glutaraldehyde-processed bovine pericardium for dural grafts in 35 patients
undergoing cranial and craniospinal operations with the objective of
providing a clinical assessment of this material and technique.

METHODS: This report is a retrospective analysis of 35 patients. All
available records were reviewed and information regarding the indication for
grafting, graft size, complications, and outcome were collected and analyzed
for all patients.

RESULTS: Indications for grafting included meningioma resection, posterior
fossa craniotomy, Chiari decompression, dural-based metastases, and trauma.
Outcomes were good or excellent in 32 patients; the three fair or poor
outcomes were not related to surgical closure. In no patient was the dural
graft a significant factor in outcome. Bovine pericardium was found to be
easily sutured to be watertight using standard suture material. The material
is relatively inexpensive and requires no additional incision. It has low
antigenicity and toxicity, good strength, and minimal elasticity.

CONCLUSION: In this clinical assessment, bovine pericardium was found to be
an excellent dural graft material.
(Neurosurgery 39:764768, 1996)

Key words: Bovine pericardium, Craniotomy, Dura mater, Graft, Meningioma




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Surgical Anatomy of the Anterior Cervical Spine: The Disc Space, Vertebral
Artery, and Associated Bony Structures

T. Glenn Pait, M.D., James A. Killefer, M.D., Kenan I. Arnautovic, M.D.

Department of Neurosurgery, University of Arkansas for Medical Sciences,
Little Rock, Arkansas (TGP, KIA), and Department of Neurosurgery (JAK), West
Virginia University, Morgantown, West Virginia

OBJECTIVE: To elucidate the relationships between the neurovascular
structures and surrounding bone, which are hidden from the surgeon by soft
tissue, and to aid in avoiding nerve root and vertebral artery injury in
anterior cervical spine surgery.

METHODS: Using six cadaveric spines, we measured important landmarks on the
anterior surface of the spine, the bony housing protecting the neurovascular
structures in the lateral disc space, and the changes that occur during the
discectomy with interbody distraction of the vertebral bodies. The
measurements included the distance between the medial borders of the longus
colli muscle at the level of each interspace; the width and height of each
disc space at the midline; the width and height of the costal process; the
distances between the cranial tip of the uncinate process (UP) and the
vertebral body (VB) above and from the tip of the UP to the vertebral
artery; the anteroposterior diameter or the extent of the disc spaces in the
midline; the height at the midpoint of the distracted disc space; the UP-VB
distance in distraction; and the width of the visible nerve root.

RESULTS: The distance between the medial borders of the longus colli muscles
increased in a rostral to caudal direction. The height of the UP was
shortest at C4C5 and greatest at C5C6; the width was narrowest at C4C5
and widest at C6C7. The width of the costal process measured from the VB to
the anterior tubercle was narrowest at C2C3 and widest at C6C7. The
midpoint height of the costal process was smallest at C6C7 and tallest at
C4C5 and C5C6. The nondistracted UP-vertebral artery distance was the
shortest at C2C3 and longest at C4C5. The nondistracted UP-VB distance
averaged 1 mm at C2C3 and C6C7 and 1.5 mm at C4C5. The height of the
distracted disc space was shortest at C2C3 and C6C7. The UP-VB distance
after distraction was greatest at C4C5. Only at the C2C3 interspace was
the nerve always above the process. The vertebral artery entered the foramen
transversarium of C6 in all the specimens.

CONCLUSION: Although avoiding unfortunate injury is not always possible,
understanding the locations and relations among the anatomic features is the
only safeguard against unwarranted damage.
(Neurosurgery 39:769776, 1996)

Key words: Costal process, Longus colli muscles, Uncinate process, Vertebral
artery




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Microsurgical Anatomy of the Infratemporal Fossa as Viewed Laterally and
Superiorly

Fotios D. Vrionis, M.D., Ph.D., William G. Cano, M.D., Carl B. Heilman, M.D.

Department of Neurosurgery, Tufts University School of Medicine and New
England Medical Center, Boston, Massachusetts

OBJECTIVE: Benign tumors involving the cavernous sinus, trigeminal nerve,
and middle cranial fossa occasionally extend to the infratemporal fossa
(ITF). In this study, we describe the microsurgical anatomy and dissection
of the ITF, as viewed laterally and superiorly. We also describe a new
bypass graft to the supraclinoid internal carotid artery using the internal
maxillary artery (IMA), which is found in the ITF.

METHODS: Twelve cadaver specimens were used. Dissection required zygomatic
arch osteotomy, downward displacement of the temporalis muscle, extensive
subtemporal craniectomy, and mild elevation of the temporal lobe together
with the dura.

RESULTS: The anatomic relationships between the lateral and medial pterygoid
muscles and the neurovascular bundle of the ITF are demonstrated. The
neurovascular bundle contains the IMA, which runs horizontally, and the main
branches of the mandibular nerve, which run vertically. The course and
anatomic variations of the IMA and inferior alveolar, lingual,
auriculotemporal, and buccal nerves are shown. The distal IMA was quite
tortuous and, when the artery was straightened, we were able to perform a
tension-free in situ IMA graft to the supraclinoid carotid artery in 9 of 12
specimens.

CONCLUSION: Knowledge of the anatomy of the ITF is a prerequisite for tumor
resection in this area. The IMA may serve as a bypass graft to the
supraclinoid internal carotid artery if the cavernous or petrous carotid
artery is involved by tumor and needs to be sacrificed.
(Neurosurgery 39:777786, 1996)

Key words: Bypass graft, Cerebral revascularization, Cranial base surgery,
Infratemporal fossa, Maxillary artery, Microsurgical anatomy




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Functional Anatomic Relationship between Brain Stem Tumors and Cranial Motor
Nuclei

Nobu Morota, M.D., Vedran Deletis, Ph.D., M.D., Mark Lee, Ph.D., M.D., Fred
J. Epstein, M.D.

Division of Pediatric Neurosurgery (NM, ML, FJE) and Department of
Anesthesiology (VD), New York University Medical Center, New York, New York

OBJECTIVE: To identify patterns of cranial motor nuclei (CMN) displacement
in cases of intramedullary brain stem tumor, using neurophysiological
mapping of motor nuclei on the floor of the fourth ventricle.

METHODS: Relationships between tumors and CMN were reviewed in 18 patients
with brain stem tumors (seven pontine, nine medullary, and two
pontomedullary tumors) and 2 with cervicomedullary junction spinal cord
tumors. CMN VII, IX/X, and XII were mapped by applying electrical stimuli
over the surgically exposed fourth ventricular floor through a handheld
probe and recording electrical activity in the appropriate cranial muscles.

RESULTS: Tumors distorted the anatomic location of CMN in repetitive
patterns according to tumor site. Three patterns were identified as follows:
Type 1, CMN located around the tumor on the floor of fourth ventricle; Type
2, one or more CMN located ventrally to the tumor; Type 3, CMN in original
anatomic position. Six of seven patients with pontine tumors showed the Type
1 pattern. Seven of nine patients with medullary tumors showed Type 2, and
the other two showed Type 1. Both patients with pontomedullary tumors showed
Type 2. One patient with a cervicomedullary junction spinal cord tumor
showed Type 1 and the other Type 3, depending on the tumor extension into
the fourth ventricle.

CONCLUSION: Pontine tumors push the CMN to around the tumor edge, suggesting
that precise localization of CMN before tumor resection is necessary to
avoid their damage. Medullary tumors grow more exophytically and compress
the CMN ventrally. Understanding patterns of CMN displacement can help
surgeons establish the surgical plan, minimize risks, and enable safer
surgery of brain stem tumors.
(Neurosurgery 39:787794, 1996)

Key words: Brain stem, Cranial motor nucleus, Fourth ventricle, Mapping,
Tumor




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Response of Spinal Cord Blood Flow to the Nitric Oxide Inhibitor
Nitroarginine

Patrick W. Hitchon, M.D., Loren J. Mouw, M.D., Thomas N. Rogge, M.S., James
C. Torner, Ph.D., Adrienne K. Miller, B.Sc.

Department of Surgery, Division of Neurosurgery (PWH, LJM, TNR, AKM), and
Department of Preventive Medicine and Environmental Health, Division of
Epidemiology (JCT), College of Medicine, The University of Iowa, Veterans
Administration Medical Center, Iowa City, Iowa

OBJECTIVE: The extent to which nitric oxide (NO) is involved in the
modulation of spinal cord blood flow (SCBF) in the uninjured and injured
cord is unknown. To elucidate these questions, the following experiments in
anesthetized rats were conducted.

METHODS: Because NO is an unstable free radical with a half-life of seconds,
its role can be understood through the study of the NO synthase inhibitor
L-NG-nitroarginine (L-NOARG). L-NOARG was administered intravenously for 30
minutes at a dose of 100 or 500 g/kg/min in 12 and 10 uninjured animals,
respectively. SCBF fluctuations at C7T1 were measured using laser doppler
flowmetry. In a second set of 12 rats, L-NOARG (500 g/kg/min) was
administered 10 minutes before spinal cord injury using a modified aneurysm
clip at C7T1 and continued for 30 minutes thereafter.

RESULTS: In the uninjured animals, L-NOARG was associated with a
dose-dependent increase in mean arterial pressure of 20 to 80% above
baseline (P = 0.0001), together with a dose-related decrease in SCBF (P =
0.0373). In the injured animals, L-NOARG was associated with a 48% increase
in mean arterial pressure. With L-NOARG, the changes in SCBF from baseline
after injury were similar to those of noninjured controls (n = 25) and
significantly less than injury controls (n = 18) or those receiving
phenylephrine (n = 8).

CONCLUSION: NO synthase inhibitors, by reducing available NO, cause systemic
vasoconstriction and a decrease in SCBF in the uninjured spinal cord. In the
injured spinal cord, the administration of L-NOARG results in a
redistribution of blood flow with an augmentation in posttraumatic SCBF at
the injury site.
(Neurosurgery 39:795803, 1996)

Key words: L-Arginine analogs, Laser doppler flowmetry, Nitric oxide, Spinal
cord blood flow




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Ultrastructural Evidence for Arteriolar Vasospasm after Spinal Cord Trauma

David L. Anthes, M.A., M.D., Elizabeth Theriault, Ph.D., Charles H. Tator,
M.D., Ph.D.

Canadian Paraplegic Association Spinal Cord Injury Research Laboratory,
Playfair Neuroscience Unit, The Toronto Hospital, University of Toronto,
Toronto,Ontario, Canada

OBJECTIVE: The primary objective of this study was to investigate the
potential contribution of vasospasm to the cascade of secondary injury
processes after traumatic spinal cord injury. Although ischemic factors have
been implicated, in that vessel rupture, compression, and intravascular
thrombosis are readily identifiable, vasospasm has been more difficult to
detect.

METHODS: The sulcal arterioles in the ventral median fissure of the cervical
spinal cord from adult rats were quantitatively examined at the
ultrastructural level up to 24 hours after compression injury.

RESULTS: There were statistically significant changes in the luminal
cross-sectional area of sulcal arterioles after spinal cord injury,
correlating directly with decreases in length and increases in width of
medial smooth muscle cells. A simple mathematical model of postinjury blood
flow is presented, suggesting an 80% decrease caused by vasospasm alone.

CONCLUSION: Our results clearly implicate vasospasm as a contributing factor
to secondary injury processes after traumatic spinal cord injury.
(Neurosurgery 39:804814, 1996)

Key words: Microcirculatory pathology, Spinal cord injury, Vasospasm




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Effect of P2-purinoceptor Antagonists on Hemolysate-induced and Adenosine
5'-Triphosphate-induced Contractions of Dog Basilar Artery in Vitro

Bogdan Sima, B.A., R. Loch Macdonald, M.D., Ph.D., Linda S. Marton, Ph.D.,
Bryce Weir, M.D., John Zhang, M.D., Ph.D.

Section of Neurosurgery, University of Chicago Medical Center, Chicago,
Illinois

OBJECTIVE: To test the hypothesis that the vasoactive effects of hemolysate
of dog erythrocytes on dog basilar artery in vitro are caused by adenosine
5'-triphosphate (ATP).

METHODS: Dog erythrocyte hemolysate was assayed for ATP by high-pressure
liquid chromatography. Dog basilar arteries were cut into rings and studied
under isometric tension to determine the effects of the P2-purinoceptor
antagonists suramin, pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid,
and reactive blue 2 on contractions induced by hemolysate, prostaglandin
F2alpha (PGF2alpha), Kcl, uridine 5'-triphosphate, and ATP.

RESULTS: Dog erythrocyte hemolysate contained 34 mol/L of ATP. Hemolysate
produced concentration-dependent contractions of dog basilar artery. Suramin
(100 mol/L) significantly inhibited contractions to hemolysate, ATP, and
uridine 5'-triphosphate but not to PGF2alpha and KCl (P < 0.05). Pyridoxal
phosphate-6-azophenyl-2',4'-disulfonic acid (100 mol/L) caused a small but
significant reduction of the contractions to hemolysate and did not affect
contractions to PGF2alpha and KCl. Reactive blue 2 (30 mol/L) produced
significant inhibition of contractions to hemolysate and PGF2alpha but did
not affect contractions to KCl.

CONCLUSION: These findings suggest that ATP mediates a smooth muscle
contractile response of hemolysate on dog basilar artery. Because
erythrocyte cytosol is known to be important in the pathogenesis of
vasospasm, these results suggest that ATP may contribute to the
vasoconstriction that occurs in vasospasm.
(Neurosurgery 39:815822, 1996)

Key words: Adenosine 5'-triphosphate, Basilar artery, Canine,
P2-purinoceptors, Subarachnoid hemorrhage, Vasospasm




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Enzyme-linked Immunosorbent Assay Quantification of Cytokine Concentrations
in Human Meningiomas

Elad I. Levy, B.S., Javier E. Paino, M.D., Prem S. Sarin, Ph.D., Allan L.
Goldstein, Ph.D., Anthony J. Caputy, M.D., Donald C. Wright, M.D., Laligam
N. Sekhar, M.D.

School of Medicine (EIL), Department of Biochemistry and Molecular Biology
(JEP, PSS, ALG), and Department of Neurological Surgery (AJC, DCW, LNS), The
George Washington University, Washington, District of Columbia

OBJECTIVE: To gain insight into the network of cytokine gene expression in
the brain tumor microenvironment, we investigated the presence of the
following cytokines in freshly excised brain tumors: interleukin (IL)-1beta,
IL-2, IL-4, and IL-6.

METHODS: Tumor specimens from nine meningiomas were grown as tissue
explants. The supernatants from the explants were tested for the presence of
the aforementioned cytokines via the enzyme-linked immunosorbent assay
method.

RESULTS: IL-6, which is thought to stimulate acute protein phase synthesis,
neovascularization, and cell proliferation, was found in all of the samples
in greater concentrations than the other cytokines tested. IL-1beta, another
stimulatory cytokine thought to be involved in acute protein phase synthesis
and cell proliferation, was also found in 100% of the samples tested, in
concentrations significantly lower than those of IL-6. As expected, the
presence of IL-2 and IL-4 was not detectable in any of the samples.

CONCLUSION: This study is the first to clearly determine the relative
concentrations of IL-1beta and IL-6, using enzyme-linked immunosorbent assay
quantification. These findings are an important precursor to future studies
using antibodies to IL-1beta and IL-6 and antibodies to IL-6 receptors to
modulate neoplastic growth both in vitro and in vivo.
(Neurosurgery 39:823829, 1996)

Key words: Cytokine, IL-1beta, IL-6, Meningioma




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Neurosurgery at the Montreal Neurological Institute and McGill University
Hospitals

William Feindel, M.D., C.M., D.Phil.

The Montreal Neurological Institute, and the Division of Neurosurgery,
Department of Neurology and Neurosurgery, McGill University, Montreal,
Canada

FOR THE PAST 60 years, the Montreal Neurological Institute and Hospital and
three associated McGill University teaching hospitals have provided a broad
course of instruction in neurosurgery and the related neurosciences. This
integrated program offers a wealth of experience in adult and pediatric
neurosurgery, based on a total of 140 beds, covering a full range of general
and subspecialty neurosurgery. The institute, recognized for many years as a
world center for epilepsy surgery, has traditional strengths in the
treatment of brain tumors and cerebrovascular and spinal disorders; it has
been at the cutting edge of brain imaging in all modalities applied to
neurosurgical diagnosis and cerebral localization, including
three-dimensional monitoring in the operating room. New approaches to
stereotactic procedures have been developed in conjunction with imaging
technology, including functional neurosurgery and the versatile McGill
double rotation method for radiosurgery with a linear accelerator.
Experience in managing trauma, pediatric cases, and general neurosurgical
problems is gained at the Montreal General Hospital, the Montreal Children's
Hospital, and the Jewish General Hospital. Well-established research units,
including burgeoning groups in neurogenetics, molecular neurobiology, and
neural regeneration, provide a wide variety of academic opportunities to
provide trainees with a sound basis for coping with the rapidly advancing
field of neurosurgery.
(Neurosurgery 39:830839, 1996)

Key words: Archibald, Edward; Cone, William; Jewish General Hospital; McGill
University; Montreal Children's Hospital; Montreal General Hospital;
Montreal Neurological Institute; Neurosurgical Education; Osler, William;
Penfield, Wilder; Royal Victoria Hospital




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Contralateral Cerebellar Hemorrhagic Infarction after Pterional Craniotomy:
Report of Five Cases and Review of the Literature

Varnavas Papanastassiou, M.D., Richard Kerr, M.S., Christopher Adams,
M.Chir.

Department of Neurological Surgery, The Radcliffe Infirmary, Oxford, England

OBJECTIVE AND IMPORTANCE: Five cases of cerebellar hemorrhagic infarction
complicating pterional craniotomy are presented. Recognition of this rare
complication may be delayed, with catastrophic consequences, because
clinicians are unaware of the possibility. We suggest that the mechanism of
this complication is dislocation of the dependent part of the cerebellum and
venous obstruction causing hemorrhagic infarction.

CLINICAL PRESENTATION: Five patients undergoing pterional craniotomies for
benign conditions (four unruptured aneurysms and one meningioma) developed
hemorrhagic infarction of the contralateral cerebellum in the postoperative
period. This resulted in obstructive hydrocephalus and brain stem
compression. A review of the literature revealed only one previous report of
a similar complication in patients with gross coagulopathy. This was not a
problem in our patients.

INTERVENTION: The time of onset of symptoms varied from immediately
postoperative to 24 hours later. Once the diagnosis was made, the
hydrocephalus was drained and the posterior fossa was decompressed.

CONCLUSION: The outcome depended on two variables: 1) the rate of
development of hemorrhagic infarction and the associated complications and
2) the amount of time that elapsed before remedial action was taken. Two
patients with the first signs of deterioration in the immediate
postoperative period had the worst outcome; one died and the other remained
severely disabled. In two patients with good neurological recovery, problems
were identified and corrected within 4 hours of the first sign of
deterioration. Rapid overdrainage of cerebrospinal fluid during
supratentorial surgery should be avoided, and the fluid volume should be
replaced before closure. Postoperative evaluation of patients whose
conditions deteriorate after supratentorial craniotomy should include
adequate imaging studies of the posterior fossa.
(Neurosurgery 39:841852, 1996)

Key words: Cerebellum, Complication, Hemorrhagic infarction, Supratentorial
craniotomy




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Direct Carotid Cavernous Fistula after Trigeminal Balloon Microcompression
Gangliolysis: Case Report

Todd A. Kuether, M.D., Oisin R. O'Neill, M.D., Gary M. Nesbit, M.D., Stanley
L. Barnwell, M.D., Ph.D.

Division of Neurosurgery and the Dotter Interventional Institute, Oregon
Health Science University, Portland, Oregon

OBJECTIVE AND IMPORTANCE: Percutaneous gangliolysis procedures may rarely be
associated with vascular complications. There are three reported cases of
carotid cavernous fistulas occurring after percutaneous retrogasserian
procedures. We present one case of acute symptomatic direct
carotid-cavernous fistula after percutaneous balloon microcompressive
trigeminal gangliolysis. This is the only reported case of this complication
associated with microcompression gangliolysis.

CLINICAL PRESENTATION: A 78-year-old woman was referred to our institution
with a history of abrupt onset of left-sided bruit, proptosis, chemosis, and
diplopia after a percutaneous retrogasserian microcompression.

INTERVENTION: Cerebral angiography revealed a large left direct carotid
cavernous fistula. Attempts at balloon embolization were unsuccessful, and
the lesion was ultimately cured by transarterial and transvenous coil
embolization.

CONCLUSION: Follow-up examination revealed no evidence of bruit or
neurological deficit. This report highlights a unique complication of
balloon gangliolysis and describes coil embolization of the fistula as the
mode of treatment.
(Neurosurgery 39:853856, 1996)

Key words: Carotid artery, Carotid-cavernous fistula, Therapeutic
embolization, Trigeminal neuralgia




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Symptomatic Hypertrophic Pacchionian Granulation Mimicking Bone Tumor: Case
Report

Toshihiko Kuroiwa, M.D., Yoshinaga Kajimoto, M.D., Tomio Ohta, M.D., Akira
Tsutsumi, M.D.

Department of Neurosurgery and Central Laboratory, Osaka Medical College,
Osaka, Japan

OBJECTIVE AND IMPORTANCE: Osteolytic lesions can be seen in various
diseases, and they also resemble the markings normally found on the cranium.
We present a rare case of symptomatic hypertrophic pacchionian granulation
mimicking bone tumor in the calvaria.

CLINICAL PRESENTATION: A 46-year-old woman suffered from a small hump
accompanied by pain in the right frontoparietal region. A plain radiograph
revealed two punched-out lesions. Precontrast-enhanced computed tomographic
scans demonstrated hypodense masses, with partial defect of the outer table
of the cranium. Magnetic resonance imaging demonstrated hypointense masses
in the T1-weighted image and hyperintense masses in the T2-weighted image,
with capsule-like contrast enhancement by gadolinium diethylenetriamine
penta-acetic acid.

INTERVENTION: The masses were totally resected with attached bone and dura.
One of them had destroyed the outer table of the cranium. The affected
portions of the masses lacked the dura and partially adhered to the brain
surface. Histologically, hypertrophic pacchionian granulation was diagnosed.

CONCLUSION: The patient has had no recurrence for 2 years. This case
suggests the need to include hypertrophic pacchionian granulation in the
differential diagnosis of punched-out lesions.
(Neurosurgery 39:860862, 1996)

Key words: Bone tumor, Meningioma, Pacchionian granulation, Punched-out
lesion




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Cervical-to-Petrous Internal Carotid Artery Saphenous Vein in Situ Bypass
for the Treatment of a High Cervical Dissecting Aneurysm: Technical Case
Report

Emmanuel Candon, M.D., Charles Marty-Ane, M.D., Pierre Pieuchot, M.D.,
Philippe Frerebeau, M.D.

Services de Neurochirurgie (EC, PF), Chirurgie Vasculaire (CM-A), and
Neuroradiologie (PP), CHU Montpellier, Montpellier, France

OBJECTIVE AND IMPORTANCE: We describe a novel cervical-to-petrous internal
carotid artery (ICA) saphenous vein in situ bypass for the treatment of a
high cervical dissecting aneurysm. The cervical ICA has no major collateral
branches and can be used as a tunnel for the vein graft.

CLINICAL PRESENTATION: A 25-year-old man was involved in a car accident. A
cerebral angiogram revealed a right ICA dissection with aneurysm formation
at the C1C2 level. The patient recovered fully and was anticoagulated. Six
months after the initial angiogram, a second angiogram disclosed ICA
stenosis (80%) and persistence of the traumatic dissecting aneurysm.
Definitive surgical bypass was considered the most appropriate course of
action.

TECHNIQUE: The horizontal portion of the petrous ICA was exposed by an
extradural subtemporal approach. The cervical arteries were exposed by a
separate cervical incision. After dividing the petrous ICA and the cervical
ICA, the cervical ICA was dilated using a Fogarty balloon embolectomy
catheter. A saphenous vein graft was inserted inside the lumen of the
cervical ICA and was anastomosed to the ICA end-to-end both proximally and
distally (cervical-to-petrous ICA in situ bypass). The graft was patent on
the follow-up angiogram.

CONCLUSION: We describe a new technique that could be considered an
alternative to the classical extra-anatomic cervical-to-petrous ICA bypass
procedures.
(Neurosurgery 39:863866, 1996)

Key words: Autologous vein graft, Extracranial-intracranial bypass, Internal
carotid artery, Telescopic principle




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Surgical Needle Design: Torsion Resistance

Edward C. Benzel, M.D., Paul J. Parisi, B.S.

University of New Mexico, School of Medicine, Division of Neurosurgery
(ECB), Albuquerque, New Mexico, and Ethicon, Inc. (PJP), Somerville, New
Jersey

OBJECTIVE: The interface between a surgical needle and forceps affects
needle-forceps stability. Stability has become more important with the
introduction of blunt-point surgical needles. The stability at the
needle-forceps interface can be assessed by quantitating resistance to both
rotation and twisting. Two commonly used surgical needles are the MO and CT
needles, which are particularly useful for soft tissue closure for which
significant strength of closure is required. Their comparison is thus of
importance to surgeons. The design of the MO needle (greater flat section
width than the CT needle) should allow for a greater resistance to rotation
at the needle-forceps junction. This theoretically makes the MO needle a
better choice when blunt-point needles (which require a greater force to
penetrate tissue) are used. The objective of this study is to document and
quantitate the differences, if any, between the CT and MO needles with
regard to rotation and twisting at the needle-forceps junction.

METHODS: To compare the efficacy of the CT and MO needles with regard to
needle-forceps stability, the resistance of the needles to rotation and
twisting was assessed using a Hios HP-10 digital torque meter.

RESULTS: The resistance to twisting of the CT and MO needles was not
significantly different. However, the MO needle is 25% more resistant to
rotation than the CT needle. This differed by 10% from the expected
difference.

CONCLUSION: The resistance to twisting is not significantly affected by
needle geometry, whereas the resistance to rotation is significantly
affected. The difference between expected and observed differences in
rotation is explained by study design.
(Neurosurgery 39:867870, 1996)

Key words: Bending, Needle forceps, Rotation, Surgical needle, Torque,
Twisting


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 1996 Williams & Wilkins

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