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The authors describe a method of harvesting autologous pericranium for duraplasty in patients with Chiari malformation Type I (CM-I) that avoids excessive exposure or a second incision. Nonautologous dural grafts have been associated with numerous complications including hemorrhage, bacteria and virus transmission, fatal Creutzfeldt-Jakob disease transmission, foreign body reaction, systemic immune response, excessive scarring, slower healing, premature graft dissolution, and wound dehiscence. Autogenous tissues have the advantage of being nonimmunogenic, nontoxic, readily available, and inexpensive. Pericranium is a preferred substrate because it is flexible, strong, and easily sutured for a watertight closure. Current literature supports the use of autogenous pericranium for dural grafting in CM-I procedures, but has heretofore failed to provide a method of harvest that avoids the complications associated with a larger exposure or second incision. The authors offer a simple alternative technique for using local pericranium in duraplasty for CM-I or other posterior fossa abnormalities.

Objective: Atypical meningioma (AM) patients often undergo gross total resection (GTR) at the time of presentation, but subsequent prognosis and optimal management remain unclear. We sought to define the long-term recurrence rate of AMs after GTR, along with factors predicting recurrence, including postoperative radiation., Methods: We performed a retrospective review of 108 AMs after GTR at our institution from 1993 to 2004. Recurrence risk factors were analyzed using multivariate Cox regression., Results: There were 600 patient-years of imaging follow-up on 48 men and 60 women. Of 108 tumors, 30 (28%) recurred 3 to 144 months after GTR (mean, 36 months). Actuarial tumor recurrence rates were 7% (1 year), 41% (5 years), and 48% (10 years). Of 108 patients, 8 received postoperative radiation without recurrence (P = 0.1). Multivariate analysis including age, sex, postoperative radiation, tumor location, MIB-1 labeling index, and 6 atypical-defining histological features identified recurrence-predicting factors: older age (hazard ratio, 1.6/decade; P = 0.01), sheeting (hazard ratio, 2.2; P = 0.025), and prominent nucleoli (hazard ratio, 2.1; P = 0.034). Recursive partitioning identified a subset, men with mitoses and prominent nucleoli, with 70% recurrence (n = 14). All patients with recurrences received radiation, and 22 of 30 patients underwent craniotomies (average, 2.7 craniotomies per patient with recurrence; range, 1-7 craniotomies). Only 1 of 22 re-resected meningiomas underwent malignant transformation. Of 30 patients with recurrence, 10 experienced tumor-induced mortality an average of 7 years after recurrence (range, 1-14 years)., Conclusion: After GTR without postoperative radiation, AMs have a high recurrence rate. Most recurrences occurred within 5 years after resection. Recurrences caused numerous reoperations per patient and shortened survival. Our finding suggesting lower recurrence rates in patients undergoing immediate postoperative radiation should be investigated in larger, prospective series.

Object: Although the manifestations of neurofibromatosis Type 2 (NF2) vary, the hallmark is bilateral vestibular schwannomas (VSs). The authors studied the clinical course and genetic basis of unilateral VSs associated with other NF2-related tumors., Methods: Forty-four adults presenting with unilateral VSs and other NF2-related tumors were identified. A comprehensive review of patient records and cranial imaging was conducted. Molecular analysis of the NF2 locus was performed in available tumors and paired blood specimens. Patient age at symptomatic onset ranged from 11 to 63 years (mean 32 years). Twenty-two patients (50%) presented with eighth cranial nerve dysfunction. Twenty-six presented with multiple lesions. Thirty-eight harbored other intracranial tumors and 27 had spinal tumors, with most lesions situated ipsilateral to the VS. No patient had a relative with NF2, although two of 63 offspring had isolated NF2-related findings. A contralateral VS developed in four patients 3 to 46 years after the symptomatic onset of a unilateral VS, and two of these patients experienced rapid progression to total deafness. Results of a Kaplan-Meier analysis identified actuarial chances of developing contralateral VS: 2.9% (3-17 years after the VS symptomatic onset of unilateral VS), 11% (18-24 years), and 28.8% (25-40 years). Mosaicism for the NF2 gene mutation was proven in eight patients., Conclusions: The authors describe the clinical features of this unique phenotype--unilateral VS with other NF2-related tumors. Persons with this phenotype should undergo evaluation and monitoring similar to that conducted in patients with NF2, and the possibility of aggressive contralateral VS formation should be considered in their treatment. Molecular genetic analysis is best performed using resected tumor specimens and will enable future studies to determine the genetic risks of individuals with mosaicism.

Objective: To determine the outcome and toxicity in patients with vestibular schwannomas treated with conventionally fractionated stereotactic radiotherapy (SRT) and to identify prognostic factors that are predictive of outcome., Methods: Between 1992 and 2001, 70 patients with vestibular schwannomas were treated with linear accelerator-based SRT in our institutions. Eleven patients had neurofibromatosis Type II (NF2). The median age was 53 years (range, 17-82 yrs). The median tumor volume was 2.4 cm3 (range, 0.05-21.1 cm3). The indications for SRT were distributed as follows: 47% newly diagnosed, 31% progressive tumors after watchful waiting, 3% adjuvant postoperative radiation, and 19% recurrent tumors after surgical resection. The median dose was 54 Gy in 1.8 Gy per fraction, prescribed to 95% of the isodose line. Relocatable stereotactic frames were used for daily treatments. The median follow-up was 45.3 months., Results: Tumor recurrence was defined as progressive enlargement of tumor on follow-up magnetic resonance imaging studies. One patient had a tumor recurrence at 38 months after SRT. The actuarial tumor control rates were 100 and 98% at 3 and 5 years, respectively. Three patients with a median tumor volume of 16.2 cm3 required surgical resection for persistent or increasing symptoms at a median of 37 months. The actuarial freedom from resection rates were 98 and 92% at 3 and 5 years, respectively. In multivariate analysis, tumor volume at time of treatment was predictive for neurosurgical intervention (surgical resection or shunt placement) after SRT (P = 0.001). The 3- and 5-year actuarial rates of freedom from any neurosurgical intervention were 100 and 97% for patients with tumor volume less than 8 cm3 and 74 and 47% respectively for patients with tumor of at least 8 cm3 (P < 0.0001). The 3-year actuarial rates of facial and trigeminal nerve preservation were 99 and 96%, respectively. Surgery before SRT was predictive of posttreatment trigeminal neuropathy. The 3-year actuarial rates of freedom from trigeminal neuropathy were 86 and 98% for patients with and without previous resection, respectively (P = 0.04). There was no difference in tumor control and cranial nerve function preservation rates seen in NF2 patients compared with non-NF2 patients. No second primary cancer or malignant transformation was observed., Conclusion: SRT in the conventionally fractionated approach results in a very favorable outcome with minimal toxicity, with results comparable to those of the best of the radiosurgery series. Patients with large tumors are more likely to undergo neurosurgical interventions after SRT. Patients who have undergone previous surgery are at increased risk of developing trigeminal neuropathy.

Objective: Hemorrhages from cerebral cavernous malformations (CMs) sometimes seem to occur in closely spaced "clusters" interspersed with long hemorrhage-free intervals. Clustering of hemorrhages could affect retrospective assessments of radiosurgery efficacy in prevention of CM rehemorrhage. However, this empirical observation had not been tested quantitatively. To test whether CM hemorrhages tend to cluster, we reviewed pretreatment rebleeding rates after a first symptomatic hemorrhage in CM patients who later underwent surgery or radiosurgery., Methods: We performed a retrospective review of 141 patients with CMs who presented with clinically overt hemorrhage, and who subsequently underwent surgery or proton beam radiosurgery during an 18-year period. Statistical models were used to analyze all events per person and identify potential variation in rebleeding risk with time after a previous hemorrhage., Results: Sixty-three of 141 patients experienced a second hemorrhage before treatment; 16 had additional hemorrhages. Five hundred thirty-eight patient years elapsed between first hemorrhages and treatment. The cumulative incidence of a second hemorrhage after the first CM hemorrhage was 14% after 1 year and 56% after 5 years. During the first 2.5 years after a hemorrhage, the monthly rehemorrhage hazard was 2%. The risk then decreased spontaneously to less than 1% per month, which represents a 2.4-fold decline (P < 0.001). Rehemorrhage rates were higher in younger patients (P < 0.01), but not in females or in patients with deep lesions. Shorter intervals between successive hemorrhages did not predict higher subsequent rehemorrhage risk., Conclusion: The rehemorrhage rate from untreated CMs is high initially, and it decreases 2 to 3 years after a previous hemorrhage. This hazard pattern generates the observed temporal clustering of hemorrhages from untreated CMs.

Intraventricular meningiomas of the lateral ventricle occur relatively rarely, but they are often large at the time of detection and present more commonly on the left side. Although the ability to resect these tumors safely has greatly improved over time, standard surgical approaches often traverse cortex close to areas of specific cortical function. Precise cortical mapping of language and sensorimotor cortices can be accomplished noninvasively by using functional magnetic resonance (fMR) imaging. The authors used fMR imaging in planning the cortical incision for resection of a large intraventricular trigone meningioma in the dominant hemisphere of a patient who, postoperatively, suffered no aphasia or hemiparesis. The authors discuss the advantages of mapping cortical function preoperatively with fMR imaging when approaching intraventricular lesions.

The retrosigmoid approach for the microsurgical removal of an acoustic neuroma (vestibular schwannoma) is described, and perioperative medical management of the patient is discussed. The techniques for monitoring facial and cochlear nerve function are presented. The supine-oblique position, skin incision, bone removal, dural opening, and initial exposure are outlined. Important points in the technique for removing acoustic neuromas and preserving hearing, when possible, are described and illustrated.

The Committee on Hearing and Equilibrium of the American Academy of Otolaryngology-Head and Neck Surgery recently published guidelines for reporting hearing preservation in the treatment of acoustic neuromas. These suggestions included pretreatment and posttreatment pure-tone hearing thresholds, word recognition scores, and hearing classification. We present a standardized reporting format that addresses the Committee's recommendations and displays individual patient audiologic data as a simple, concise plot of posttreatment hearing results. To illustrate the use of the recommended format, preoperative and postoperative hearing data from our institution are reported. Such reporting criteria will facilitate comparative reviews of studies of hearing preservation after surgical or radiotherapeutic management of acoustic neuromas, while providing specific data for individual patient outcome analysis.

Objective/hypothesis: In specific clinical situations, endoscopes offer better visualization than the microscope during acoustic neuroma (vestibular schwannoma) surgery and can therefore decrease the incidence of the postoperative complications of cerebrospinal fluid (CSF) leakage and recurrence of tumor. This study was undertaken to determine if the use of adjunctive endoscopy provides complementary information to the operating surgeon during surgery for acoustic neuromas., Method: Seventy-eight patients with acoustic neuromas underwent tumor excision by two neurotologists (PAW., D.S.P.), together with their respective neurosurgical partners, via a retrosigmoid (suboccipital) approach (n = 68), translabyrinthine approach (n = 7), or middle cranial fossa approach (n = 3). Endoscopy with a rigid glass lens endoscope was used during tumor removal to examine posterior fossa neurovascular structures, and after tumor excision to inspect the internal auditory canal (IAC), inner ear, and middle ear, depending on the approach used. One of the authors (D.S.P.) has not used adjunctive endoscopy during resections via the translabyrinthine and middle cranial fossa approaches, and therefore, these cases were excluded from the data collection and analysis., Results: Complete tumor excision was achieved in 73 patients. Endoscopy allowed improved identification of tumor and adjacent neurovascular relationships in all cases. In addition, residual tumor at the fundus of the IAC (n = 11) and exposed air cells (n = 24) not seen with the microscope during retrosigmoid approaches were identified endoscopically. In one of the translabyrinthine cases, the endoscope allowed identification of open air cells not visualized with the microscope. None of the 78 patients developed CSF rhinorrhea. Incorporating the endoscope did not significantly increase operative time., Conclusions: Endoscopy can be performed safely during surgery to remove acoustic neuromas. The adjunctive use of endoscopy may offer some advantages including improved visualization, more complete tumor removal, and a lowered risk of CSF leakage.

The indications for the surgical management of supratentorial cavernous malformations are outlined and the results following operation are presented in this article. Surgery is indicated for most patients who present with seizures, neurologic deficit, or headache. The surgical approaches to lesions in the cerebrum are described. The operative morbidity and mortality are low. Over 95% of all patients have excellent or good results and return to their previous level of activity.

Objective: As more information evolves regarding the natural history of cavernous malformations (CMs), the risks of operative intervention must be balanced against nonoperative management. In an attempt to better delineate the surgical risks for operable CMs, we undertook a retrospective analysis of 94 patients with 97 CMs surgically excised at the Massachusetts General Hospital., Methods: Data regarding surgical complications and outcome measures, including neurological status and seizure outcome, were analyzed., Results: The incidence of transient neurological morbidity was 20.6%, but only 4 of the 97 operations (4.1%) resulted in persistent disabling neurological complications and 2 (2.1 %) in nondisabling deficits. There was no operative mortality. Brain stem lesions (n=14) were associated with the highest incidence of neurological complications, both transient and persistent (odds ratio, 4.8; 95% confidence interval, 1.5-15.7). The overall neurological outcome was excellent or good in 89.7% of all lesions: 96.8% of lobar CMs (n=63), 64.2% of brain stem CMs (n=14), 87.5% of cerebellar CMs (n=8), 100% of cranial nerve CMs (n=4), and 75% of spinal cord CMs (n=8). Patients with brain stem and spinal cord CMs were in poorer preoperative neurological condition than were patients with CMs in other locations and therefore had a significantly reduced level of function after surgery (P < 0.01). There was improvement in 35.7% of the patients with brain stem lesions and 62.5% of the patients with spinal cord lesions after surgery. In the 38 patients presenting with seizures, 97% were seizure-free after surgery., Conclusion: The risks of operative management of CMs varies based on location. When evaluating patients with operable CMs for surgery, the incidence of complications as well as final neurological outcome should be carefully weighed against the existing knowledge of the natural history of lesions managed expectantly.

Acute pulmonary edema after a large air embolus occurring during neurosurgery is a recognized phenomenon. The authors describe the course of a 76-year-old man who presented with noncardiogenic pulmonary edema shortly after undergoing resection of a high convexity meningioma. Transthoracic Doppler sonography, however, showed no evidence of a large intraoperative emboli; the evidence for ongoing but low-magnitude air embolus included visualization of bone aspiration of irrigant before bone-edge waxing, transient intraoperative declines in end-tidal CO2 tension, and an increase of the fraction of inspired oxygen to maintain adequate saturation after removal of the craniotomy flap. There was no hemodynamic instability noted. The airspace disease was self-limited and resolved on supportive treatment after approximately 1 week, as would be expected for pulmonary edema caused by a single large intravenous air embolus. The authors present this case as the first report of pulmonary edema resulting from low-level air embolus occurring during craniotomy. This situation may go unrecognized intraoperatively but can cause the same significant postoperative morbidity as larger, more easily identified air emboli.

The subtemporal transpetrous approach to the petroclival region uses a combination of techniques, including a petrosectomy and a subtemporal and suboccipital craniotomy. Ligation of the greater petrosal sinus, sigmoid sinus, and retraction of the temporal lobe affords wide exposure to the petroclival region and ventral brainstem and minimizes the need for facial nerve translocation. This approach has been successfully used in the management of 10 large tumors of the region, including chondrosarcomas, chordomas, meningiomas, and schwannomas. The history and evolution of this technique and its relation to other similar approaches is discussed.

Patients with satisfactory facial nerve function [House-Brackmann (HB) grade I or II] immediately after acoustic neuroma surgery are at risk for delayed facial paralysis. To study this problem, 255 consecutive patients who underwent acoustic neuroma excision with facial nerve preservation were identified. Delayed facial paralysis occurred in 62 (24.3%) patients; 90% ultimately recovered to their initial postoperative HB grade, and 98.3% recovered to within one grade of their initial HB level. Paralysis occurred at an average of 3.65 postoperative days (range, 1-16 days). The average time to maximal recovery for those with changes of 1, 2, 3, and 4 HB grades was 5.6, 21.5, 39.8, and 50.5 weeks, respectively. The early onset of paralysis (< 48 h after surgery) resulted in shorter average recovery times. Of patients who demonstrated nerve deterioration to grades IV-VI, 20 of 38 required tarsorrhaphy or gold-weight placement. We conclude that the over-whelming majority of patients with delayed facial paralysis after acoustic neuroma surgery do eventually recover to their postoperative HB grade. The magnitude and timecourse of delayed facial paralysis are predictive factors for subsequent recovery.

Selective vestibular neurectomy is an effective treatment for intractable vertigo of peripheral vestibular origin when preservation of hearing is a goal. The retrolabyrinthine and retrosigmoid-intracanalicular approaches have been used predominantly at our institutions over the last 10 years. The results and complications of these two techniques were compared. No significant differences were found between hearing results in these two patient groups. The retrosigmoid-internal auditory can approach yielded better control of recurrent episodic vertigo, as well as superior ablation of postoperative ice-water caloric responses (p < 0.05). Surgical complications, including the incidence of cerebrospinal fluid leakage (greater in retrolabyrinthine approach) and postoperative headache (more prevalent in retrosigmoid approach), were also analyzed. To further evaluate the results of this study, data were reanalyzed and compared with previously published reports of selective vestibular nerve section.

Anterior midline approaches are safe and appropriate for extradural lesions of the central brain base. They are occasionally warranted for intradural lesions as well. Transnasal routes expose the clivus well. They are readily expanded superiorly, inferiorly, and laterally. Recent innovations are reductive; they expand exposure with less facial disassembly. Lateral and most intradural extensions of lesions warrant more lateral approaches.

In 1989, the Acoustic Neuroma Association established a multisurgeon, multi-institutional registry to collect data related to the treatment of patients with acoustic neuroma. This report analyzes information from the 1579 surgically treated patients who were entered in the registry between January 1, 1989, and February 28, 1994.

Deleterious effects of Teflon strand placement during microvascular decompression (MVD) for hemifacial spasm are rare. In this report, a patient who had previously undergone suboccipital MVD for hemifacial spasm presented 3 years postoperatively with a progressive asymmetric sensorineural hearing loss and magnetic resonance imaging evidence of an enlarging ipsilateral gadolinium enhancing 1-cm cerebellopontine angle lesion. At surgery a granuloma was found displacing the structures of the internal auditory canal. Histologically, evidence of a Teflon fiber-induced giant cell granuloma was identified. This paper reviews the literature of Teflon-induced histopathology as it relates to posterior fossa MVD surgery, as well as its relation to this previously unreported complication.

Anterior approaches to the clivus must provide excellent visualization of the lesion, give adequate access for dural repair, and be cosmetically acceptable. Most current approaches enter through the nasopharynx or oropharynx, with either palatal, maxillary, or mandibular splitting for greater exposure. We have modified the transfacial approach described by others, which provides excellent access to the clivus along its rostrocaudal extent. A lateral rhinotomy incision is used and carried along the base of the right alae nasi and columella. The nasal bones are osteotomized bilaterally, and the nose is rotated on a pedicle flap, thus opening the entire nasal cavity to view. The septum and medial maxillary walls are removed. This provides excellent visualization of the ethmoid, sphenoid, posterior nasopharynx, and upper oropharynx. At the conclusion of the procedure, the nasal incision is closed, with good cosmesis. A case of recurrent chordoma of the middle and lower clivus is presented to exemplify this technique. The approach has since been used to approach clivus tumors and midline aneurysms of the vertebrobasilar system.

In a review of 68 meningiomas with good quality computed tomography (CT) scans, 40% had significant CT edema, in the sense of having low absorption around tumor. Two distinct patterns of edema could be distinguished. One was a diffuse white matter process appearing to represent active transudation of water into white matter; this occurred in 43% of tumors with edema. The second, occurring in 57% of tumors with edema, was a localized peritumoral process. This distinction has important pathophysiologic and clinical implications. The diffuse pattern did not appear to reflect tumor size: it was found in 54.6% of tumors from 2 to 4 cm in diameter and 33% of tumors over 4 cm. It appeared more often in tumors of the lateral sphenoid wing or subfrontal region and was more often associated with atypical and syncytial histological type, (p < 0.05, two-tailed t test.). It occurred disproportionately often in atypical tumors and appeared to reflect some intrinsic property of the tumor rather than compression of surrounding structures.

Headache after acoustic neuroma surgery is known to occur clinically, but has not been studied systematically until recently. In the present study, 155 patients were surveyed regarding their experience of headache and associated symptoms following resection of an acoustic neuroma: 73 percent (n = 98) of patients undergoing suboccipital resection of an acoustic neuroma and 53 percent (n = 8) of patients undergoing translabyrinthine resection of acoustic neuroma complained of headache following surgery. The average pain intensity was greater for the suboccipital approach. Only 9 percent (n = 14) reported troublesome or frequent headaches preoperatively. Headache was described most often as tension type, with episodic acute exacerbations mimicking migraine. Clinical observations suggest that most patients are treated successfully with various combinations of reassurance, tricyclic antidepressants, nonsteroidal anti-inflammatory medications, trigger-point injections, adjunctive stress management techniques (relaxation), and physical therapy. The impact of recurrent headache on work and recreational function is notable. Several possible pathophysiological and biopsychosocial models are proposed to account for the prevalent headache problem. Although spontaneous resolution usually occurs over time, additional study is needed to determine the natural history of postoperative headache once it occurs.

Two cases are reported of third ventricle masses that were clinically and radiographically indistinguishable from pure colloid cysts. A 21- and a 36-year-old man presented with a 5-year and 10-day histories of headache, respectively. Magnetic resonance (MR) imaging revealed smooth, homogeneous masses in the anterior third ventricle that were iso- to hyperintense on T1-weighted MR images and hyperintense on T2-weighted images. There was little enhancement with intravenous contrast material. In both patients, craniotomies were performed and histopathological examination revealed xanthogranulomas of the choroid plexus with only microscopic foci of colloid cyst-like structures. These cases illustrate that xanthogranulomas of the third ventricle may clinically and radiologically mimic pure colloid cysts, that a range of MR imaging signals can be seen, and that craniotomy rather than stereotactic aspiration is the indicated treatment.

Over a 22-year-period (1967-1989) 80 patients 70 years of age and older underwent surgery for resection of a benign intracranial tumor. This group included 56 meningiomas and 24 acoustic neuromas. Forty-five of the tumors were completely excised, whereas 35 were partially removed. Tumor regrowth was documented in seven patients during the follow-up period, five of whom underwent additional surgery for resection of recurrent tumor. Thirty-six (64.3%) of the patients with meningiomas had only a minimal or no preoperative neurologic deficit, whereas twenty (35.7%) had a major deficit. Fifty-three (94.6%) patients who underwent surgery for resection of their meningioma made a good recovery (48 were improved or unchanged and five had minimal nonincapacitating worsening), one (1.8%) was worse, and two (3.6%) died. Fourteen (58.3%) of the patients with acoustic neuromas had only a minimal or no preoperative neurologic deficit, whereas 10 (41.7%) had a major deficit. Twenty-two (91.7%) of the patients who underwent surgery for resection of their acoustic neuroma made a good recovery (18 were improved or unchanged and four had minimal nonincapacitating worsening), two (8.3%) were worse, and none died. We conclude that, when indicated, surgery for intracranial meningiomas and schwannomas can be offered to patients 70 years of age and older with acceptable morbidity and mortality.

Bilateral craniectomy in a woman comatose and decerebrate after a subarachnoid hemorrhage, resulted in normal mentation in 3 days. The dramatic recovery is unmatched in our experience. The rationale rested on clinicopathologic studies showing that in such cases brain swelling was the cause of death, the brain being otherwise intact. Emergency surgery to relieve the tamponade seemed reasonable. The question is whether the procedure has a role in those patients who fail to respond to current therapeutic measures. The arguments in favor, presented herein, are illustrated by three pathologic studies selected from our longtime experience.

Arachnoid granulations provide the pathway for drainage of cerebrospinal fluid from the subarachnoid space into the dural venous sinus system. They frequently produce small, well-defined indentations on the inner table of the calvarium that are easily recognized on radiographic studies and gross examination of the skull. We report a series of four giant cystic arachnoid granulations presenting as large "destructive" osteolytic lesions that required surgical exploration. The cysts were filled with cerebrospinal fluid and were delineated by a thin fibrous wall that contained peripheral clusters of arachnoid cells. We discuss the pathologic and radiographic differential diagnosis of osteolytic skull lesions and present a hypothesis regarding the formation of giant cystic arachnoid granulations.

A safe technique is described for performing a lateral posterior fossa craniotomy to gain access to the cerebellopontine angle. The method makes use of currently available high-speed air drills. Thus, it is possible to replace the removed bone at the conclusion of the procedure and to re-establish normal tissue planes while providing rigid protection to the posterior fossa.

The management of patients with cavernous angioma continues to evolve. Our current recommendations for management are as follows. 1. Patients who are asymptomatic are observed. 2. Patients with acute severe or progressive neurological deficits are operated upon. 3. Patients presenting with a seizure are usually operated upon but some are observed, depending on the factors discussed. 4. Patients with a single hemorrhage in the cerebrum, cerebellum, or spinal cord are usually operated upon. When the hemorrhage is in the brainstem, thalamus, or basal ganglia, they are observed. 5. Patients with a recurrent hemorrhage are usually operated upon but there are exceptions when the lesion is in a deep area with high surgical risk.

The surgical results in 78 recent cases of total removal of unilateral acoustic neuroma in which an attempt was made to preserve cochlear function have been added to the authors' previous series of 66 cases to evaluate the factors influencing the ability to preserve useful hearing. Useful hearing was defined by speech reception threshold no poorer than 70 dB and a discrimination score of at least 15%. Analysis using a logistic regression model showed that certain preoperative clinical parameters such as tumor size, speech discrimination score, and gender were significantly correlated with hearing outcome. Favorable outcome was significantly correlated with smaller tumor size, higher preoperative speech discrimination score, and male sex. From this data, an explicit formula was devised for predicting hearing outcome for an individual patient. In four cases with useful hearing preserved, there was improvement of greater than 15 percentage points in speech discrimination scores. While preoperative auditory brainstem responses were not predictive of hearing preservation, monitoring of intraoperative auditory evoked potentials was predictive of hearing outcome in selected cases. Specifically, when wave V was unchanged at the end of the operation, even if it may have been transiently lost during surgery, useful hearing was invariably preserved.

Cavernous angiomas of the spinal cord are rare lesions that can cause severe neurological symptoms. We add a series of 6 patients with intramedullary cavernous angiomas of the spinal cord to 30 patients with 31 histologically verified lesions already described in the literature. Four types of clinical presentation were seen in the 36 patients: 1) discrete episodes of neurological deterioration with varying degrees of recovery between episodes (13 patients); 2) slow progression of neurological decline (12 patients); 3) acute onset of symptoms with rapid decline (8 patients); and 4) acute onset of mild symptoms with subsequent gradual decline lasting weeks to months (3 patients). Of the 36 patients, 25 (69%) were women and 11 (31%) were men. The peak age of presentation was in the fourth decade. The thoracic spinal cord was affected in more than half the patients, with the cervical cord being the next most common location. Histological examination demonstrated the closely apposed vascular channels characteristic of cavernous angiomas. While most vascular channels were thickened and hyalinized, three angiomas had foci of small vessels resembling a capillary angioma. The available data suggest that surgical management of intramedullary angiomas should attempt complete extirpation. The lesions are often well circumscribed with a glial plane between the lesion and normal cord. However, spinal cord angiomas, unlike cranial lesions, have little room for enlargement before devastating symptoms occur. We achieved complete excision in all of our patients, who are all ambulatory and have improved symptoms. Little, if any, increase in neurological deficit was caused by myelotomy and lesion excision. These spinal lesions should be considered for surgery early, before repeated hemorrhage or enlargement can occur.