Showing papers in "Neurosurgery in 1997"

Complications of Transsphenoidal Surgery: Results of a National Survey, Review of the Literature, and Personal Experience

Abstract: OBJECTIVE:The primary objectives of this report were, first, to determine the number and incidence of complications of transsphenoidal surgery performed by a cross-section of neurosurgeons in the United States and, second, to ascertain the influence of the surgeon's experience with the procedure on

Development and implementation of intraoperative magnetic resonance imaging and its neurosurgical applications.

Abstract: Objective We describe the development and implementation of a new open configuration magnetic resonance imaging (MRI) system, with which neurosurgical procedures can be performed using image guidance. Our initial neurosurgical experience consists of 140 cases, including 63 stereotactic biopsies, 16 cyst drainages, 55 craniotomies, 3 thermal ablations, and 3 laminectomies. The surgical advantages derived from this new modality are presented. Methods The 0.5-T intraoperative MRI system (SIGNA SP, Boston, MA), developed by General Electric Medical Systems in collaboration with the Brigham and Women's Hospital, has a vertical gap within its magnet, providing the physical space for surgery. Images are viewed on monitors located within this gap and can also be acquired in conjunction with optical tracking of surgical instruments, establishing accurate intraoperative correlations between instrument position and anatomic structures. Results A wide range of standard neurosurgical procedures can be performed using intraoperative MRI. The images obtained are clear and provide accurate and immediate information to use in the planning and assessment of the progress of the surgery. Conclusion Intraoperative MRI allows lesions to be precisely localized and targeted, and the progress of a procedure can be immediately evaluated. The constantly updated images help to eliminate errors that can arise during frame-based and frameless stereotactic surgery when anatomic structures alter their position because of shifting or displacement of brain parenchyma but are correlated with images obtained preoperatively. Intraoperative MRI is particularly helpful in determining tumor margins, optimizing surgical approaches, achieving complete resection of intracerebral lesions, and monitoring potential intraoperative complications.

Continuous assessment of the cerebral vasomotor reactivity in head injury

Abstract: OBJECTIVE: Cerebrovascular vasomotor reactivity reflects changes in smooth muscle tone in the arterial wall in response to changes in transmural pressure or the concentration of carbon dioxide in blood. We investigated whether slow waves in arterial blood pressure (ABP) and intracranial pressure (ICP) may be used to derive an index that reflects the reactivity of vessels to changes in ABP. METHODS: A method for the continuous monitoring of the association between slow spontaneous waves in ICP and arterial pressure was adopted in a group of 82 patients with head injuries. ABP, ICP, and transcranial doppler blood flow velocity in the middle cerebral artery was recorded daily (20- to 120-min time periods). A Pressure-Reactivity Index (PRx) was calculated as a moving correlation coefficient between 40 consecutive samples of values for ICP and ABP averaged for a period of 5 seconds. A moving correlation coefficient (Mean Index) between spontaneous fluctuations of mean flow velocity and cerebral perfusion pressure, which was previously reported to describe cerebral blood flow autoregulation, was also calculated. RESULTS: A positive PRx correlated with high ICP (r = 0.366; P < 0.001), low admission Glasgow Coma Scale score (r = 0.29; P < 0.01), and poor outcome at 6 months after injury (r = 0.48; P < 0.00001). During the first 2 days after injury, PRx was positive (P < 0.05), although only in patients with unfavorable outcomes. The correlation between PRx and Mean Index (r = 0.63) was highly significant (P < 0.000001). CONCLUSION: Computer analysis of slow waves in ABP and ICP is able to provide a continuous index of cerebrovascular reactivity to changes in arterial pressure, which is of prognostic significance.

Management of 1000 vestibular schwannomas (acoustic neuromas): surgical management and results with an emphasis on complications and how to avoid them.

Abstract: OBJECTIVE : To identify the actual benefits and persisting problems in treating vestibular schwannomas by the suboccipital approach, the results and complications in a consecutive series of 1000 tumors surgically treated by the senior author were analyzed and compared with experiences involving other treatment modalities. METHODS : Pre- and postoperative clinical statuses were determined and radiological and surgical findings were collected and evaluated in a large database for 962 patients undergoing 1000 vestibular schwannoma operations at Nordstadt's neurosurgical department from 1978 to 1993. RESULTS : By the suboccipital transmeatal approach, 979 tumors were completely removed ; in 21 cases, deliberate partial removal was performed either in severely ill patients for decompression of the brain stem or in an attempt to preserve hearing in the last hearing ear. Anatomic preservation of the facial nerve was achieved in 93% of the patients and of the cochlear nerve in 68%. Major neurological complications included 1 case of tetraparesis, 10 cases of hemiparesis, and caudal cranial nerve palsies in 5.5% of the cases. Surgical complications included hematomas in 2.2% of the cases, cerebrospinal fluid fistulas in 9.2%, hydrocephalus in 2.3%, bacterial meningitis in 1.2%, and wound revisions in 1.1%. There were 11 deaths occurring at 2 to 69 days postoperatively (1.1%). The techniques that were developed for avoidance of complications are reported. The analysis identifies preexisting severe general and/or neurological morbidity, cystic tumor formation, and major caudal cranial nerve deficits as relevant risk factors. CONCLUSION : The current treatment options of complete tumor resection with ongoing reduction of morbidity are well fulfilled by the suboccipital approach. By careful patient selection, the mortality rate should be further reduced to below 1%.

Decompressive bifrontal craniectomy in the treatment of severe refractory posttraumatic cerebral edema.

Abstract: Objective The management of malignant posttraumatic cerebral edema remains a frustrating endeavor for the neurosurgeon and the intensivist. Mortality and morbidity rates remain high despite refinements in medical and pharmacological means of controlling elevated intracranial pressure; therefore, a comparison of medical management versus decompressive craniectomy in the management of malignant posttraumatic cerebral edema was undertaken. Methods At the University of Virginia Health Sciences Center, 35 bifrontal decompressive craniectomies were performed on patients suffering from malignant posttraumatic cerebral edema. A control population was formed of patients whose data was accrued in the Traumatic Coma Data Bank. Patients who had undergone surgery were matched with one to four control patients based on sex, age, preoperative Glasgow Coma Scale scores, and maximum preoperative intracranial pressure (ICP). Results The overall rate of good recovery and moderate disability for the patients who underwent craniectomies was 37% (13 of 35 patients), whereas the mortality rate was 23% (8 of 35 patients). Pediatric patients had a higher rate of favorable outcome (44%, 8 of 18 patients) than did adult patients. Postoperative ICP was lower than preoperative ICP in patients who underwent decompression (P = 0.0003). Postoperative ICP was lower in patients who underwent surgery than late measurements of ICP in the matched control population. A statistically significant increased rate of favorable outcomes was seen in the patients who underwent surgery compared to the matched control patients (15.4%) (P = 0.014). All patients who exhibited sustained ICP values above 40 torr and those who underwent surgery more than 48 hours after the time of injury did poorly. Evaluation of the 20 patients who did not fit into either of those categories revealed a 60% rate of favorable outcome and a statistical advantage over control patients (P = 0.0001). Conclusion Decompressive bifrontal craniectomy provides a statistical advantage over medical treatment of intractable posttraumatic cerebral hypertension and should be considered in the management of malignant posttraumatic cerebral swelling. If the operation can be accomplished before the ICP value exceeds 40 torr for a sustained period and within 48 hours of the time of injury, the potential to influence outcome is greatest.

Interstitial chemotherapy with carmustine-loaded polymers for high-grade gliomas: a randomized double-blind study.

Abstract: OBJECTIVE: To find out the effect of carmustine (bischloroethyl-nitrosourea) combined with a biodegradable polymer in the treatment of malignant (Grades III and IV) gliomas, applied locally, at the time of the primary operation. METHODS: Prospective, randomized double-blind study of an active treatment group versus a placebo group. Conducted at the Departments of Neurosurgery of the University Hospitals of Helsinki, Tampere, and Turku in Finland and Trondheim in Norway. The study consisted of 32 patients (16 in each treatment group) enrolled between March 23, 1992, and March 19, 1993. The study was planned to include 100 patients but had to be terminated prematurely, because the drug that was being used had become unobtainable. The main outcome measures included the survival times of patients after the operations and the application of an active drug or placebo. RESULTS: The median time from surgery to death was 58.1 weeks for the active treatment group versus 39.9 weeks for the placebo group (P = 0.012). For 27 patients with Grade IV tumors, the corresponding times were 39.9 weeks for the placebo group and 53.3 weeks for the active treatment group (P = 0.008). At the end of the study, six patients were still alive, five of whom belonged to the active treatment group. CONCLUSION: Carmustine applied locally in a biodegradable polymer at the time of primary operation, seems to have a favorable effect on the life span of patients with high-grade gliomas.

Management of 1000 vestibular schwannomas (acoustic neuromas): the facial nerve--preservation and restitution of function.

Abstract: Objective Although the rate of reported facial nerve preservation after surgery for vestibular schwannomas continuously increases, facial nerve paresis or paralysis is a frequent postsurgical sequelae of major concern The major goal of this study was to define criteria for the right indication, timing, and type of therapy for patients with palsies despite anatomic nerve continuity and those with loss of anatomic continuity Methods One thousand vestibular schwannomas were surgically treated at the Department of Neurosurgery at Nordstadt Hospital from 1978 to 1993 Of 979 cases of complete removal and 21 cases of deliberately partial removal, the facial nerve was anatomically preserved in 929 cases (93%) The rate of preservation is increasing, as is evidenced in the most recent cases, and preservation is supported by special electrophysiological monitoring The facial nerve was anatomically severed in 60 cases (6%) It was anatomically lost in previous operations that were performed elsewhere in 11 cases (1%) In case of nerve discontinuity (42 cases), immediate nerve reconstruction by one of three available intracranial procedures (within the cerebellopontine angle, intracranial-intratemporal, intracranial-extracranial) was performed in the same surgical setting In case of loss of the proximal facial nerve stump at the brain stem, early reanimation by combination with the hypoglossal nerve was achieved in most patients within weeks after tumor surgery In a few patients with anatomic nerve continuity but absence of reinnervation for 10 to 12 months, a hypoglossal-facial combination was applied All the patients with partial or with complete palsies were treated in a special follow-up program of regular controls and of modulation of physiotherapeutic treatment every 3 to 6 months Results In intracranial nerve reconstruction at the cerebellopontine angle, 61 to 70% of patients regained complete eye closure and an overall result equivalent to House-Brackmann Grade 3 Hypoglossal-facial reanimation led to Grade 3 in 79% The duration between the onset of paralysis and the reconstructive procedure is decisive for the quality of the outcome These data are discussed in view of other treatment options and certain parameters influencing outcome Conclusions This management contains three major principles as follows: 1) preservation of facial nerve continuity in function by the aid of intraoperative monitoring, 2) early nerve reconstruction in case of lost continuity, and 3) scheduled follow-up program for all patients with incomplete or complete palsies

Management of 1000 vestibular schwannomas (acoustic neuromas): clinical presentation

Abstract: OBJECTIVE : Despite good knowledge of the key symptoms of vestibular schwannomas and their significance for surgical results, the evolution of symptoms and signs and their relation to tumor extension still need thorough investigation. METHODS : From 1978 to 1993, operations were performed by the same surgeon (M.S.) on 1000 vestibular schwannomas at the Neurosurgical Department of Nordstadt Hospital. The vestibular schwannomas were diagnosed in 962 patients, including 522 female patients (54%) and 440 male patients (46%) ; the mean age was significantly higher in female patients (47.6 yr) than in men (45.2 yr). We focused our analysis on the incidence of subjective disturbances versus objective morbidity, on the sequence of symptom onset, and on symptom duration and symptomatology versus tumor size and extension. RESULTS : The most frequent clinical symptoms were disturbances of the acoustic (95%), vestibular (61%), trigeminal (9%), and facial (6%) nerves. Symptom duration was 3.7 years for hearing loss, 1.9 years for facial paresis, and 1.3 years for trigeminal disturbances. Symptom incidence and duration did not strictly correlate with tumor size. Key symptoms of various tumor extension classes precipitated the diagnosis, such as trigeminal disturbances in large tumors with brain stem compression or tinnitus in small neuromas. In cases of trigeminal or facial nerve symptoms, the overall duration of symptomatology was much shorter. According to the subjective perception of the patients, between only one- and two-thirds of nerve disturbances were noticed. Patients with preoperative deafness had become deaf either chronically (23%) or suddenly (3%) ; even in cases of moderate hearing deficit that lasts a long time, deafness can occur suddenly. The rate of tinnitus was higher in hearing than in deaf patients ; however, deafness does not mean relief from tinnitus, because this symptom persists in 46% of preoperatively deaf patients. Vestibular disturbances most often occur as some unsteadiness while walking or as vertigo, and the symptoms frequently are fluctuating, not constant. CONCLUSION : Differences in tumor biology can be underestimated and are not visible on radiological scans. For example, intrameatal tumors, despite their small size, present with a duration of symptoms that is representative of the larger tumors and are most frequently associated with vestibular symptoms and with tinnitus. Large tumors with brain stem compression present with relatively shorter symptom durations and at a younger age ; both factors are suggestive of especially fast tumor growth. The clinical findings presented in this study promote new consideration of the dynamics of tumor growth and of the affected neural tissues.

Management of 1000 vestibular schwannomas (acoustic neuromas): hearing function in 1000 tumor resections.

Abstract: OBJECTIVE: The realistic chances of hearing preservation and the comparability of international results on hearing preservation in complete microsurgical vestibular schwannoma resections were the focus of this study in a large patient population treated by uniform principles. METHODS: One thousand vestibular schwannomas were operated on at Nordstadt Neurosurgical Department, from 1978 to 1993, by the senior surgeon (MS). There were 1000 tumors in 962 patients, i.e., 880 patients with unilateral tumors and 82 patients operated on for bilateral tumors in neurofibromatosis-2 (120 cases). Preservation of the cochlear nerve was attempted whenever possible. The audiometric data were analyzed by the Nordstadt classification system and graded in steps of 30 dB by audiometry and in steps of 10 to 30% by speech discrimination; for comparability, the data were also evaluated by the criteria of Gardner, Shelton, and House, and they were assessed in relation to the Hannover tumor extension grading system. RESULTS: Anatomic cochlear nerve preservation was achieved in 682 of 1000 cases (68%), as well as in some preoperatively deaf patients, a very few of whom regained some hearing. Of a total of 732 cases with some preoperative hearing, anatomic cochlear nerve preservation was achieved in 580 cases (79%) and functional cochlear nerve preservation in 289 (39.5%); analysis over time revealed an actual preservation rate of 47% in the most recent 200 cases. Specific factors, such as gender, tumor extension, preoperative hearing quality, and symptom duration, were investigated for their predictive value for hearing preservation. Male gender, small to medium tumor size (mainly extending within the cerebellopontine cistern; Classes T2 and T3), good to moderate hearing (up to 40-dB loss), and short duration of hypoacusis (<1.5 yr) or of vestibular disturbances (<0.7 yr) were advantageous factors, with chances of hearing preservation between 47 and 88%. CONCLUSION: Functional cochlear nerve preservation in complete microsurgical resection should belong to the contemporary standard of treatment goals.

Deep Brain Stimulation for Intractable Pain: A 15-Year Experience

Abstract: Objective During the past 15 years, we prospectively followed 68 patients with chronic pain syndromes who underwent deep brain stimulation (DBS). The objective of our study was to analyze the long-term outcomes to clarify patient selection criteria for DBS. Methods Patients were referred from a multidisciplinary pain clinic after conservative treatment failed. Electrodes for DBS were implanted within the periventricular gray matter, specific sensory thalamic nuclei, or the internal capsule. Each patient was followed on a 6-monthly follow-up basis and evaluated with a modified visual analog scale. Results Follow-up periods ranged from 6 months to 15 years, with an average follow-up period of 78 months. The mean age of the 54 men and 14 women in the study was 51.3 years. Indications for DBS included 43 patients with failed back syndrome, 6 with peripheral neuropathy or radiculopathy, 5 with thalamic pain, 4 with trigeminal neuropathy, 3 with traumatic spinal cord lesions, 2 with causalgic pain, 1 with phantom limb pain, and 1 with carcinoma pain. After initial screening, 53 of 68 patients (77%) elected internalization of their devices; 42 of the 53 (79%) continue to receive adequate relief of pain. Therefore, effective pain control was achieved in 42 of 68 of our initially referred patients (62%). Patients with failed back syndrome, trigeminal neuropathy, and peripheral neuropathy fared well with DBS, whereas those with thalamic pain, spinal cord injury, and postherpetic neuralgia did poorly. Conclusion DBS in selected patients provides long-term effective pain control with few side effects or complications.

Safety and Efficacy of Endovascular Treatment of Acutely Ruptured Aneurysms

Abstract: OBJECTIVE: To study the safety and efficacy of endovascular treatment of acutely ruptured aneurysms with Guglielmi detachable coils. METHODS: From August 1992 until December 1995, 75 patients were referred for endovascular treatment of acutely ruptured aneurysms. There were 49 women and 26 men, with a mean age of 55 years. Patients were classified according to the Hunt and Hess grading system. There were 18 Grade I patients (24%), 13 Grade II patients (17%), 30 Grade III patients (40%), 11 Grade IV patients (15%), and 3 Grade V patients (4%). Fifty patients (66%) were treated within 48 hours, and 64 (85 %) were treated within 1 week of hemorrhage. The most frequently treated aneurysms were located at the basilar bifurcation (32%), anterior communicating artery (16%), posterior communicating artery (15%), and ophthalmic segment of the carotid artery (11%). Most of the aneurysms were smaller than 15 mm (77%). Fifty-six percent of the aneurysms had small ( 4 mm) necks, and 44% had wide (>4 mm) necks. Clinical follow-up was performed at 6 months, and results were classified according to the Glasgow Outcome Scale (GOS). Control angiograms were performed immediately, at 6 months, and yearly thereafter. RESULTS: Immediate angiographic results were considered to be satisfactory in 58 patients (77%) (complete obliteration, 40%; residual neck and dog ear, 37%). Technical failures occurred in 5 patients (7%), and 12 patients experienced some residual opacification of their aneurysms (16%). The procedure-related mortality and morbidity rate was 8%. At 6 months, the outcomes were as follows: GOS score of 1, 50 patients (66.7%); GOS score of 2, 4 patients (5.3%); GOS score of 3, 4 patients (5.3%); and GOS score of 5, 17 patients (22.7%). The main causes of death and disability at 6 months were the direct effect of the initial hemorrhage (9%), delayed ischemia (6.7%), subsequent bleeding (4%), intraprocedural rupture (4%), open surgical complications (3%), and unrelated deaths (4%). Six-month angiographic follow-up data were available for 50 patients (67%). The morphological results were considered to be satisfactory in 44 of these 50 patients (88%) (complete occlusion, 46%; residual neck or dog ear, 42%). CONCLUSION: Endovascular treatment of acutely ruptured aneurysms was attempted without clinically significant complication in 92% of the patients. The morphological results were unsatisfactory in 23% of the patients. Complete obliteration of the sac, with or without residual neck, is essential to prevent subsequent bleeding, which occurred in 5% of the patients. The overall outcome at 6 months was similar to that of surgical series, despite a selected group of patients with negative prognostic factors.

Repairing Holes in the Head: A History of Cranioplasty

Abstract: Cranioplasty is almost as ancient as trephination, yet its fascinating history has been neglected. There is strong evidence that Incan surgeons were performing cranioplasty using precious metals and gourds. Interestingly, early surgical authors, such as Hippocrates and Galen, do not discuss cranioplasty and it was not until the 16th century that cranioplasty in the form of a gold plate was mentioned by Fallopius. The first bone graft was recorded by Meekeren, who in 1668 noted that canine bone was used to repair a cranial defect in a Russian man. The next advance in cranioplasty was the experimental groundwork in bone grafting, performed in the late 19th century. The use of autografts for cranioplasty became popular in the early 20th century. The destructive nature of 20th century warfare provided an impetus to search for alternative metals and plastics to cover large cranial defects. The metallic bone substitutes have largely been replaced by modern plastics. Methyl methacrylate was introduced in 1940 and is currently the most common material used. Research in cranioplasty is now directed at improving the ability of the host to regenerate bone. As modern day trephiners, neurosurgeons should be cognizant of how the technique of repairing a hole in the head has evolved.

Intraoperative diagnostic and interventional magnetic resonance imaging in neurosurgery.

Abstract: OBJECTIVE:The benefits of intraoperative magnetic resonance (MR) imaging for diagnostic and therapeutic measures are as follows: 1) intraoperative update of data sets for navigational systems, 2) intraoperative resection control of brain tumors, and 3) frameless and frame-based on-line MR-guided int

Risk factors for neurosurgical site infections after craniotomy: a prospective multicenter study of 2944 patients. The French Study Group of Neurosurgical Infections, the SEHP, and the C-CLIN Paris-Nord. Service Epidémiologie Hygiène et Prévention.

Abstract: Objective To determine the incidence and risk factors of surgical site infections (SSIs) after craniotomy and to test the risk index score proposed by the National Nosocomial Infections Surveillance (NNIS) system, which, to our knowledge, has not been validated in neurosurgery to date. Methods During a 15-month period, every adult patient undergoing craniotomy in 10 neurosurgical units was prospectively evaluated for development and risk factors of SSI. The follow-up period was at least 30 days. SSIs were defined according to the Center for Disease Control definitions. Incidence was calculated per patient. Multivariate analyses were conducted at first to include all significant risk factors of univariate analysis and then only those known preoperatively. Finally, the NNIS risk index was tested in this population. Results Of a total of 2944 patients, 117 patients (4%) with SSIs were observed, including 30 with wound infections, 14 with bone flap osteitis, 56 with meningitis, and 17 with brain abscesses. Independent risk factors for SSIs were postoperative cerebrospinal fluid leakage (odds ratio, 145; 95% confidence interval, 72-293) and subsequent operation (odds ratio, 7; 95% confidence interval, 4-12). Independent predictive risk factors were emergency surgery, clean-contaminated and dirty surgery, an operative time longer than 4 hours, and recent neurosurgery. Absence of antibiotic prophylaxis was not a risk factor. The NNIS risk index was effective in identifying at-risk patients. Conclusion Independent risk factors for SSIs after craniotomy involve postoperative events. However, the NNIS risk index is effective in identifying at-risk patients.

One-year Outcome after Decompressive Surgery for Massive Nondominant Hemispheric Infarction

Abstract: OBJECTIVE: Massive cerebral infarction is often accompanied by early death secondary to transtentorial herniation. We have tested the hypothesis that decompressive hemicraniectomy for massive nondominant cerebral infarction is lifesaving in a series of 14 patients presenting with right hemispheric infarction and clinical signs of uncal herniation and impending death. We have further analyzed, in prospective follow-up examinations, the levels of physical, psychiatric, and social disabilities in these patients. METHODS: The methods used included retrospective analysis to determine rates of immediate mortality and morbidity after surgical intervention. Prospective follow-up data were obtained to determine the level of recovery in surviving patients after 1 year. Standardized measures of outcome to assess physical, psychiatric, and social recovery included the Barthel Index, Zung Depression Scale, and Reintegration to Normal Living Index. RESULTS: With decompressive hemicraniectomy, we were able to prevent death secondary to transtentorial herniation in all cases; 11 patients experienced long-term survival after the procedure, and three deaths were related to non-neurological causes. We observed that 8 of the 11 surviving patients were at home, were functioning with minimal to moderate assistance, and had Barthel scores greater than 60. The remaining three patients were severely disabled. Seven of the 11 survivors were able to walk at 1 year after undergoing the procedure. Depression and failure to reintegrate socially were experienced by most patients. CONCLUSION: This series confirms the lifesaving nature of hemicraniectomy in patients deteriorating because of cerebral edema after infarction. In patients younger than 50 years, recovery to a state of near-independence is possible.

The role of transvenous embolization in the treatment of intracranial dural arteriovenous fistulas.

Abstract: OBJECTIVE: To evaluate the role of transvenous embolization in the treatment of intracranial dural arteriovenous fistulas (DAVFs), including its efficacy and safety. METHODS: We retrospectively studied the charts of 24 patients (21 women and 3 men) treated for an intracranial DAVF since 1990 in whom a transvenous approach was attempted either alone (16 patients) or in combination with arterial embolization (8 patients). There were 12 cavernous sinus, 9 transverse-sigmoid sinus, 2 inferior petrosal sinus, and 1 intradiploic fistulas. Three fistulas were Type I, 12 were Type IIa, and 9 were Type IIa+b, according to the revised Djindjian's classification. Transvenous embolic agents included coils (17 patients), detachable balloons (6 patients), bucrylate (2 patients), and silk sutures (1 patient). RESULTS: Anatomic cure was proven in 21 patients (87.5%). Clinical cure was obtained in 23 cases (96%), as follows: 15 patients with a single transvenous approach, 6 with a combined arteriovenous approach, and 2 with an arterial approach after failure of venous access. There was one persistent cavernous fistula despite coil packing of the cavernous sinus. Complications were as follows: five transient and one permanent sixth nerve palsies in cavernous DAVFs, two transient labyrinthic dysfunctions in transverse sinus DAVFs, and one subarachnoid hemorrhage without sequelae. CONCLUSION: Transvenous embolization is a useful and safe approach in the management of intracranial DAVFs.

Surgical and neurological complications in a series of 708 epilepsy surgery procedures. Commentaries

Abstract: OBJECTIVE: There are few modern data on the complications of surgery for epilepsy from the neurosurgeon's point of view. A survey of complications observed in a large current epilepsy surgery series is presented to facilitate the assessment of a risk:benefit ratio, which must be known when planning for epilepsy surgery and counseling patients. METHODS: A series of 429 consecutive patients operated on during 6.5 years in the newly established University of Bonn epilepsy surgery program was, in part, retrospectively, and, in larger part, prospectively analyzed for complications originating from 279 invasive diagnostic procedures and 429 therapeutic procedures. Neuropsychological and psychiatric complications as well as the rate of failure to control seizures are not addressed in this article. RESULTS: Two hundred and seventy-nine temporal operations, 59 frontal operations, 22 other extratemporal operations, 33 callosotomies, 3 multilobectomies, and 33 hemispherectomies were performed. Complications were grouped into general surgical and neurological complications. No mortality resulted from 708 invasive procedures. Two hundred and seventy-nine invasive diagnostic procedures (various combinations of strip, grid, and depth electrode insertions) resulted in 3.6% transient morbidity (2.9% surgical complications, 0.7% neurological complications) and 0.7% permanent morbidity (dysphasia). During 429 therapeutic procedures, 33 surgical complications were encountered. None of these resulted in permanent morbidity, except for the necessity for permanent shunt insertion in three patients. Wound infection was the most frequent surgical complication, but we were able to demonstrate a steady decrease during the 6.5-year observation period. The total rate of neurological complications in 429 therapeutic procedures was 5.4%, with 3.03% causing transient morbidity and 2.33% causing permanent morbidity. CONCLUSION: Our data indicate that epilepsy surgery can be performed with an acceptable rate of resultant morbidity. The indications for epilepsy surgery, the learning curve determined, and the results from other series are discussed in the light of these figures.

The role of motor evoked potentials during surgery for intramedullary spinal cord tumors.

Abstract: Objective This is a prospective study of the methodology and clinical applications of motor evoked potentials (MEPs) during surgery for intramedullary spinal cord tumors. Methods Transcranial electrical stimulation was used to activate corticospinal motoneurons, and the traveling waves of the spinal cord were recorded through catheter-electrodes placed epi- or subdurally. Intraoperative MEP monitoring was performed in 32 consecutive patients (age range, 1-50 yr) undergoing resection of intramedullary spinal cord tumors. In 19 patients, MEPs were present before myelotomy (monitorable group), and in 10 patients, MEPs were absent before myelotomy (unmonitorable group). Placement of an epidural electrode was not possible in two patients, and technical problems prevented recording in one. Results MEP amplitudes decreased intraoperatively by more than 50% of baseline in three patients, all of whom had postoperative paraplegia. Two of these patients recovered within 1 week after surgery, and one remained paraplegic. None of the patients with preserved MEP amplitude (> 50%) sustained immediate significant postoperative deterioration. Motor function was significantly deteriorated 1 week after surgery in one patient in the monitorable group and in five patients in the unmonitorable group. MEP monitorability was significantly associated with good surgical outcome for adult patients (P 0.6). Preoperative motor status and surgical outcome were not significantly associated for the adult (P = 0.13) or pediatric groups (P > 0.4). Conclusion MEP monitorability was a better predictor of functional outcome than the patient's preoperative motor status for the adult group. Significant predictors of MEP monitorability in the adult group were preoperative motor function (P 0.4), associated syrinx (P > 0.3), or tumor location (P > 0.5). In the pediatric group, none of the examined factors were associated with MEP monitorability (P > 0.3). A decline of more than 50% in MEP amplitude during tumor removal should serve as a serious warning sign to the surgeon.

Prediction of obliteration after gamma knife surgery for cerebral arteriovenous malformations.

Abstract: OBJECTIVE:To define the factors of importance for the obliteration of cerebral arteriovenous malformations (AVMs), thus making a prediction of the probability for obliteration possible.METHODS:In 945 AVMs of a series of 1319 patients treated with the gamma knife during 1970 to 1990, the relationship

Genetics of intracranial aneurysms.

Abstract: The etiology and pathogenesis of intracranial aneurysms are clearly multifactorial, with genetic factors playing an increasingly recognized role. Intracranial aneurysms have been associated with numerous heritable connective tissue disorders, which account for at least 5% of cases. Of these disorders, the most important are Ehlers-Danlos syndrome Type IV, Marfan's syndrome, neurofibromatosis Type 1, and autosomal dominant polycystic kidney disease; the association with intracranial aneurysms, however, has been firmly established only for polycystic kidney disease. Familial intracranial aneurysms are not rare but account for 7 to 20% of patients with aneurysmal subarachnoid hemorrhage and are generally not associated with any of the known heritable connective tissue disorders. First-degree relatives of patients with aneurysmal subarachnoid hemorrhage are at an approximately fourfold increased risk of suffering ruptured intracranial aneurysms, compared to the general population. Various possible modes of inheritance have been identified in families with intracranial aneurysms, suggesting genetic heterogeneity. Although the benefits have never been quantified, screening for asymptomatic intracranial aneurysms should be considered in families with two or more affected members. The yield of such a screening program may approximate 10%. Although it is unlikely that there is a single gene with major effect, much effort is currently being directed at locating intracranial aneurysm genes.

Pathological consideration of a "blister-like" aneurysm at the superior wall of the internal carotid artery: case report.

Abstract: OBJECTIVE AND IMPORTANCE:Although the incidence is low, a very small aneurysm with a thin wall and no neck arises at the superior wall of the supraclinoid portion of the internal carotid artery and is called a "blister-like" aneurysm. However, the pathogenesis of such a vascular lesion remains uncer

Quantitative imaging study of extent of surgical resection and prognosis of malignant astrocytomas.

Abstract: OBJECTIVE: This study used quantitative radiological imaging to determine the effect of surgical resection on postoperative survival of patients with malignant astrocytomas. Previous studies relied on the surgeons' impressions of the amount of tumor removed, which is a less reliable measure of the extent of resection. METHODS: Information concerning possible prognostic factors was collected for 75 patients undergoing magnetic resonance imaging or computed tomography preoperatively and within 10 days postoperatively. Image analysis of the neuroradiological studies was conducted to quantify pre- and postoperative total tumor volumes and enhancing volumes. Univariate and multivariate proportional hazards models were used to analyze the regression of survival regarding 22 covariates that might affect survival. The covariates that were entered included age, gender, tumor grade, cumulative radiation dose, chemotherapy, seizures as a first symptom, Karnofsky performance status at presentation, pre- and postoperative total and enhancing tumor volumes, ratio of pre- to postoperative total and enhancing tumor volumes, tumor location, surgeon's impression of the degree of resection, and subsequent surgery. RESULTS: There were 23 patients with anaplastic astrocytomas and 52 with glioblastomas multiforme. The estimated mean survival time was 27 months for patients undergoing gross total resection, 33 months for subtotal resection, and 13 months for open or stereotactic biopsy. Five factors that were significant predictors of survival in multivariate analysis were tumor grade, age, Karnofsky performance status, radiation dose, and postoperative complications (P < 0.05). In univariate analysis, tumor grade, radiation dose, age, Karnofsky status, complications, presence of enhancing tumor in postoperative imaging, and postoperative volume of enhancing tumor were significantly associated with survival (P < 0.05). CONCLUSION: We conclude that the most important prognostic factors affecting survival of patients with anaplastic astrocytomas and glioblastomas multiforme are tumor grade, age, preoperative performance status, and radiation therapy. Postoperative complications adversely affect survival. Aggressive surgical resection did not impart a significant increase in survival time. Surgical resection may improve survival, but its importance is less than that of other factors and may be demonstrable only by larger studies.

Survival benefit of stereotactic radiosurgery for patients with malignant glial neoplasms.

Abstract: OBJECTIVE: During an 8-year interval, we evaluated the survival benefit of stereotactic radiosurgery performed in 64 patients with glioblastomas multiforme (GBM) and 43 patients with anaplastic astrocytomas (AA). METHODS: Adjuvant radiosurgery was performed either before disease progression or for recurrent tumor at the time of disease progression. Clinical and imaging follow-up data were obtained for all patients. The diagnosis of GBM was obtained by performing craniotomies in 41 patients and by performing stereotactic biopsies in 23. The diagnosis of AA was obtained by performing craniotomies in 19 patients (44%) and by performing biopsies in 24. RESULTS: Of the entire series, the median survival time after initial diagnosis for patients with GBM was 26 months (standard deviation [SD], 19 mo; range, 5-79 mo) and the median survival time after radiosurgery was 16 months (SD, 16 mo; range, 1-74 mo). The 2-year survival rate was 51%. No survival benefit was identified for patients who underwent intravenously administered chemotherapy in addition to radiosurgery (P = 0.97). After undergoing radiosurgery, 12 patients (19%) underwent craniotomies and resections and 4 (6%) underwent subsequent radiosurgery for regional or remote recurrence. For 45 patients who underwent radiosurgery as part of the initial management plan, the median survival time after diagnosis was 20 months. Of the entire series, the median survival time after diagnosis for patients with anaplastic astrocytomas was 32 months (SD, 23 mo; range 5-96 mo) and the median survival time after radiosurgery was 21 months (SD, 18 mo; range 3-93 mo). The 2-year survival rate was 67%. Ten patients (23%) underwent subsequent craniotomies at a mean of 8 months after initial surgery, and two underwent subsequent radiosurgery. There was no acute neurological morbidity after radiosurgery. Histologically proven radiation necrosis occurred in one patient with GBM (1.6%) and two patients with AA (4.7%). For 21 patients for whom radiosurgery was part of the initial management plan, the median survival time after diagnosis was 56 months. CONCLUSION: In comparison to historical controls, improved survival benefit after radiosurgery was identified for patients with GBM and patients with AA. Although this survival benefit may be related to our selection of patients for radiosurgery based on their having smaller tumor volumes, no selection was made based on location. We observed that radiosurgery was safe and well tolerated. Its effectiveness as an adjuvant therapy deserves a properly stratified randomized trial.

Risk Factors for Neurosurgical Site Infections after Craniotomy: A Prospective Multicenter Study of 2944 Patients

Abstract: OBJECTIVE To determine the incidence and risk factors of surgical site infections (SSIs) after craniotomy and to test the risk index score proposed by the National Nosocomial Infections Surveillance (NNIS) system, which, to our knowledge, has not been validated in neurosurgery to date. METHODS During a 15-month period, every adult patient undergoing craniotomy in 10 neurosurgical units was prospectively evaluated for development and risk factors of SSI. The follow-up period was at least 30 days. SSIs were defined according to the Center for Disease Control definitions. Incidence was calculated per patient. Multivariate analyses were conducted at first to include all significant risk factors of univariate analysis and then only those known preoperatively. Finally, the NNIS risk index was tested in this population. RESULTS Of a total of 2944 patients, 117 patients (4%) with SSIs were observed, including 30 with wound infections, 14 with bone flap osteitis, 56 with meningitis, and 17 with brain abscesses. Independent risk factors for SSIs were postoperative cerebrospinal fluid leakage (odds ratio, 145; 95% confidence interval, 72-293) and subsequent operation (odds ratio, 7; 95% confidence interval, 4-12). Independent predictive risk factors were emergency surgery, clean-contaminated and dirty surgery, an operative time longer than 4 hours, and recent neurosurgery. Absence of antibiotic prophylaxis was not a risk factor. The NNIS risk index was effective in identifying at-risk patients. CONCLUSION Independent risk factors for SSIs after craniotomy involve postoperative events. However, the NNIS risk index is effective in identifying at-risk patients.

The jugular foramen: microsurgical anatomy and operative approaches.

Abstract: The jugular foramen, based on these studies of microsurgical anatomy, is divided into three compartments: two venous and a neural or intrajugular compartment. The venous compartments consist of a larger posterolateral venous channel, the sigmoid part, which receives the flow of the sigmoid sinus, and a smaller anteromedial venous channel, the petrosal part, which receives the drainage of the inferior petrosal sinus. The petrosal part forms a characteristic venous confluens by also receiving tributaries from the hypoglossal canal, petroclival fissure, and vertebral venous plexus. The petrosal part empties into the sigmoid part through an opening in the medial wall of the jugular bulb between the glossopharyngeal nerve anteriorly and the vagus and accessory nerves posteriorly. The intrajugular or neural part, through which the glossopharyngeal, vagus, and accessory nerves course, is located between the sigmoid and petrosal parts at the site of the intrajugular processes of the temporal and occipital bones, which are joined by a fibrous or osseous bridge. The glossopharyngeal, vagus, and accessory nerves penetrate the dura on the medial margin of the intrajugular process of the temporal bone to reach the medial wall of the internal jugular vein. The operative approaches, which access the foramen and adjacent areas and are demonstrated in a stepwise manner, are the postauricular transtemporal, retrosigmoid, extreme lateral transcondylar, and preauricular subtemporal-infratemporal approaches.

Continuous Monitoring of Cerebral Substrate Delivery and Clearance: Initial Experience in 24 Patients with Severe Acute Brain Injuries

Abstract: OBJECTIVE Current neuromonitoring techniques in severe human head injury often fail to detect the causes of clinical deterioration. A sensor is now available for continuous monitoring of brain oxygen tension, carbon dioxide tension, and pH values. In this study, brain tissue oxygen tension was used to differentiate patients at risk for brain ischemia and to predict outcome. METHODS The multiparameter sensor was inserted into brain tissue, along with a standard ventriculostomy catheter and a microdialysis probe, in 24 patients. Lactate and glucose were measured by high-pressure liquid chromatography in hourly dialysate samples. RESULTS Patients who experienced a good recovery (n = 8) sustained a mean brain partial oxygen pressure of 39 +/- 4 mm Hg, brain partial carbon dioxide pressure (PCO2) of 50 +/- 8 mm Hg, and a brain pH of 7.14 +/- 0.12. Patients with moderate to severe disability (n = 6) sustained a mean brain partial oxygen pressure of 31 +/- 5 mm Hg, brain PCO2 of 47 +/- 2 mm Hg, and a brain pH of 7.11 +/- 0.12. Ten patients who died or remained vegetative sustained a mean brain partial oxygen pressure of 19 +/- 8 mm Hg, a brain PCO2 of 64 +/- 21 mm Hg, and a brain pH of 6.85 +/- 0.41. Mean brain PCO2 levels of 90 to 150 mm Hg were consistently observed after cerebral circulatory arrest or brain death. Dialysate lactate and glucose were less clearly correlated to outcome than brain oxygen tension. Dialysate glucose was extremely low in all patients and zero in most patients who died. CONCLUSION Brain oxygen pressure, brain carbon dioxide pressure, and brain pH measurements, as well as a microdialysis probe for glucose and lactate analysis, may optimize the management of comatose neurosurgical patients by allowing a fuller understanding of the dynamic factors affecting brain metabolism.

Follow-up results of microvascular decompression in trigeminal neuralgia and hemifacial spasm.

Abstract: Objective We evaluated the follow-up results of microvascular decompression in 1032 patients with trigeminal neuralgia (TN) and hemifacial spasm (HFS), who underwent operations between 1976 and 1991 and were followed for more than 5 years. Method Patients were divided into two groups, and their follow-up results were compared and studied. The early series, Group A (1976-1986), comprised 588 patients (127 with TN and 461 with HFS) followed from 10 to 20 years (mean, 12.6 +/- 2.1 yr), and the recent series, Group B (1987-1991), comprised 444 patients (154 with TN and 290 with HFS) followed from 5 to 9 years (mean, 7.0 +/- 1.4 yr). Results The immediate postoperative cure rates were 92.9% in Group A and 96.7% in Group B for TN and 97.4% in Group A and 98.3% in Group B for HFS. Satisfactory results obtained by the follow-up study were 80.3% in Group A and 82.5% in Group B for TN and 84.2% in Group A and 89.0% in Group B for HFS. Incomplete cure rates were 7.1% in Group A and 3.3% in Group B for TN and 2.6% in Group A and 1.7% in Group B for HFS. Recurrence rates were 10.2% in Group A and 6.5% in Group B for TN and 8.9% in Group A and 6.9% in Group B for HFS. Postoperative hearing dysfunction occurred in 7.1% of patients with TN in Group A and 4.5% in Group B and 9.1% of patients with HFS in Group A and 3.7% in Group B. Conclusion Improved methods of repositioning the affected vessels and of straightening the axis of the trigeminal nerve are important to obtain satisfactory follow-up results after microvascular decompression.

Embolization of the nidus of brain arteriovenous malformations with n-butyl cyanoacrylate.

Abstract: OBJECTIVE : To demonstrate that nidus embolization of brain arteriovenous malformations (AVMs) with Histoacryl (B. Braun, Melsungen, Germany) is effective and yields low morbidity and mortality rates. METHODS : We present a retrospective analysis of 54 brain AVMs treated at the University of Illinois at Chicago from April 1994 to December 1995. Treatment modalities included embolization in all cases and then surgical resection or radiosurgery. INSTRUMENTATION : The nidus was reached with the combined use of a Magic microcatheter (Balt, Montmorency, France) and a Terumo 0.010-inch guidewire. TECHNIQUE : Embolization was performed only when the tip of the microcatheter was wedged into the nidus of the AVMs with no reflux of contrast proximally. The embolization was performed using simultaneous biplane roadmapping with the patient under general anesthesia without Amytal testing. RESULTS : Twenty-six of 54 patients are still waiting for more radical treatment. Two deaths and two minor and one severe permanent neurological deficit occurred. Three patients were cured with embolization alone ; 11 patients were cured after surgical resection. Three patients underwent radiosurgery, with one cure after 1 year. CONCLUSION : Nidus embolization with Histoacryl is an effective technique that permits complete cure of a large number of brain AVMs, with or without surgical resection and/or radiosurgery.

Management of vestibular schwannomas (acoustic neuromas): auditory and facial nerve function after resection of 120 vestibular schwannomas in patients with neurofibromatosis 2.

Abstract: OBJECTIVE: Vestibular schwannomas (VSs) affect young patients with Neurofibromatosis 2 (NF-2) and cause very serious problems for hearing, facial expression, and brain stem function. Our objective was to determine a therapy concept for the right timing and indication of neurosurgical therapy. METHODS: In 1000 consecutive VS resections, 120 tumors in 82 patients with NF-2 were surgically treated by the same surgeon (MS) at the Department of Neurosurgery at Nordstadt Hospital from 1978 to 1993. The mean age of the patients was 27.5 years. Sixty tumors were surgically treated in 41 male patients, and 60 tumors were surgically treated in 41 female patients. Bilateral tumor resection was performed in 38 patients (76 operations, after previous partial surgery in 15 cases elsewhere), and unilateral operations were performed in 44 patients, 5 of whom had undergone ipsi- or contralateral surgery that was performed elsewhere. The operative and clinical findings are evaluated and compared with the data of patients without NF-2. RESULTS: In 105 cases, complete tumor resections were achieved. In 15 cases, deliberate subtotal resections were performed. These were for brain stem decompression in 4 cases and for hearing preservation in the last hearing ear in 11 cases, with successful preservation in 8 of the 11. Pre- and postoperative hearing rates were higher in male than in female patients (70% in male versus 65% in female patients before surgery and 40.5 versus 31%, respectively, after surgery). Hearing was preserved in 29 of 81 ears (36%). The rate of preservation was 24% in cases of large tumors and 57% in cases of small tumors (<30 mm). Twenty-one of 82 patients (26%) were bilaterally deaf before surgery. Twenty-five patients had uni- or bilateral hearing after surgery (i.e., 41% of those with preoperative hearing or 30.5% of the whole group). Anatomic facial nerve preservation was achieved in 85%. The facial nerve was reconstructed intracranially at the cerebellopontine angle by sural grafting in 17 cases and by hypoglossal-facial reanimation in 5. Two deaths occurred 1 and 3 months postsurgically as a result of malignant tumor growth with brain stem dysfunction and respiratory problems. In summary, for patients with NF-2, the presentation ages are lower, tumor progression is faster, the chances of anatomic and functional nerve preservation are lower, the chances of good outcomes are best when surgery is performed early and when there is good preoperative hearing function, and the danger of sudden hearing loss is higher. The chances and danger often differ from side to side among individual patients. CONCLUSION: The indication and the timing of tumor resections are in some respects different from normal VS handling and are dependent on the tumor extension and related necessity of brain stem decompression and on the auditory function. As an optimal goal, completeness of resection with functional cochlear nerve preservation is formulated, and as an acceptable compromise, subtotal microsurgical resection with functional cochlear nerve preservation in the last hearing ear is suggested.