Cordula Matthies

Management of 1000 Vestibular Schwannomas (Acoustic Neuromas): Surgical Management and Results with an Emphasis on Complications and How to Avoid Them

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 Nordstadts 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%.

Management of 1000 Vestibular Schwannomas (Acoustic Neuromas): The Facial Nerve-Preservation and Restitution of Function

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): Hearing Function in 1000 Tumor Resections

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.

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

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 Vestibular Schwannomas (Acoustic Neuromas): Auditory and Facial Nerve Function after Resection of 120 Vestibular Schwannomas in Patients with Neurofibromatosis 2

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.

Prophylactic intravenous magnesium sulfate for treatment of aneurysmal subarachnoid hemorrhage: A randomized, placebo-controlled, clinical study

Objective:To examine whether the maintenance of elevated magnesium serum concentrations by intravenous administration of magnesium sulfate can reduce the occurrence of cerebral ischemic events after aneurysmal subarachnoid hemorrhage. Design:Prospective, randomized, placebo-controlled study. Setting:Neurosurgical intensive care unit of a University hospital. Interventions:One hundred ten patients were randomized to receive intravenous magnesium sulfate or to serve as controls. Magnesium treatment was started with a bolus of 16 mmol, followed by continuous infusion of 8 mmol/hr. Serum concentrations were measured every 8 hrs, and infusion rates were adjusted to maintain target levels of 2.0–2.5 mmol/L. Intravenous administration was continued for 10 days or until signs of vasospasm had resolved. Thereafter, magnesium was administered orally and tapered over 12 days. Measurements and Main Results:Delayed ischemic infarction (primary end point) was assessed by analyzing serial computed tomography scans. Transcranial Doppler sonography and digital subtraction angiography were used to detect vasospasm. Delayed ischemic neurologic deficit was determined by continuous detailed neurologic examinations; clinical outcome after 6 months was assessed using the Glasgow outcome scale. Good outcome was defined as Glasgow outcome scale score 4 and 5. The incidence of delayed ischemic infarction was significantly lower in magnesium-treated patients (22% vs. 51%; p = .002); 34 of 54 magnesium patients and 27 of 53 control patients reached good outcome (p = .209). Delayed ischemic neurologic deficit was nonsignificantly reduced (9 of 54 vs. 15 of 53 patients; p = .149) and transcranial Doppler-detected/angiographic vasospasm was significantly reduced in the magnesium group (36 of 54 vs. 45 of 53 patients; p = .028). Fewer patients with signs of vasospasm had delayed cerebral infarction. Conclusion:These data indicate that high-dose intravenous magnesium can reduce cerebral ischemic events after aneurysmal subarachnoid hemorrhage by attenuating vasospasm and increasing the ischemic tolerance during critical hypoperfusion.

Resting regional cerebral glucose metabolism in advanced Parkinson's disease studied in the off and on conditions with [18F]FDG-PET

Studies of resting regional cerebral glucose consumption (rCMRGlc) in nondemented patients with Parkinsons disease (PD) have produced conflicting results, reporting both reduced and normal metabolism in advanced disease and reduced or normal metabolism after dopaminergic therapy. To investigate these issues, [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) was performed in 11 nondemented PD patients with advanced disease and 10 age‐matched controls. PD patients were studied after withdrawal of all dopaminergic medication to produce a practically defined off condition, and a second time 1 hour after levodopa, resulting in a clinical on state. Dynamic PET scans and simultaneous arterialised venous blood samples of [18F] acticvity were obtained. A graphical approach was used to generate parametric images of rCMRGlc and statistical parametric mapping to localise significant metabolic changes in PD. Compared with controls, global rCMRGlc was reduced in the on but not in the off condition in PD. In both states, significant regional reductions of glucose uptake were found in the parietal, frontal, temporal cortex, and caudate nucleus. Reductions correlated with the severity of disability in frontal and temporal cortex. Direct comparison between on and off conditions revealed relatively greater reductions of uptake in the ventral/orbital frontal cortex and the thalamus during on. Results suggest that cortical and caudate hypometabolism are common in advanced PD and that caution is mandatory if [18F]FDG PET is being used to differentiate advanced PD from dementia and progressive supranuclear palsy where similar reductions are seen. Furthermore, in PD, administration of levodopa is associated with further hypometabolism in orbitofrontal cortex; an area known to be relevant for reversal learning where performance is typically impaired after dopaminergic treatment.

Auditory brainstem implant: Part I. auditory performance and its evolution over time

Objective Evaluation of auditory performance and its evolution over time in patients with the auditory brainstem implant. Study Design Prospective study. Setting Tertiary referral center. Patients and Methods Between May 1996 and April 2000, 14 patients with neurofibromatosis type 2 underwent implantation with a multichannel auditory brainstem implant. Auditory performance data were obtained in 13 patients who had used their device on a regular daily basis for 1 to 41 months (average 19 months). Hearing evaluation was based on the results of four tests (vowel confusion, consonant confusion, Freiburger numbers, and speech-tracking test), which were performed with and without lip-reading at regular intervals after device activation. Results 12 patients received auditory sensation through the auditory brainstem implant immediately after device activation. In one patient, because of postoperative electrode migration, device activation was not successful. In this case, after the electrode array was repositioned, activation was successful. The results of the audiovisual mode 2 weeks after device activation revealed a lip-reading enhancement above the chance level in about 50% of the patients in the vowel confusion and speech-tracking tests and in 70% of the patients in the consonant confusion test. Lip-reading enhancement improved within the first 6 months and then entered a plateau phase, which was more prominent in the monosyllabic vowel and consonant tests. In the auditory alone mode, more than half of the patients showed their first positive result in the vowel test 3 months after device activation, but it took about 6 months until half of the patients revealed a result above the chance level in the consonant and Freiburger numbers tests. Open set speech recognition in the auditory alone mode (in the speech-tracking test) was not common and happened relatively late (within 1 year or later). Discussion and Conclusion Although auditory sensation appeared immediately after device activation, a period of 6 months was necessary for relearning and adaptation of the central auditory system to the altered form of auditory information presented by the auditory brainstem implant.

Arachnoid cysts of the posterior fossa

BACKGROUND The surgical indications and management of posterior fossa arachnoid cysts (AC) are still controversial. Different surgical techniques and management have already been suggested for arachnoid cysts of the posterior fossa. AC involving the posterior fossa and especially the cerebellopontine angle may carry a high surgical morbidity because of the involvement of important neurovascular structures (e.g., brain stem and cranial nerves). Only long-term follow-up will determine the best surgical technique for such lesions. METHODS Between 1990 and 1996 a total of 12 patients underwent surgery for arachnoid cysts involving the posterior fossa. In seven cases AC were located within the cerebellopontine angle (CPA), in three cases in the CPA with major extension dorsal to the brainstem, and in two cases at the CPA extending into the internal auditory canal. RESULTS A suboccipital retrosigmoid approach was performed in all patients. Radical resection of the cyst could be accomplished in all but one case. There was no mortality. Major postoperative morbidity was present in one case because of an intraoperative air embolism in the semisitting position and strong adherence of the cyst wall to the surrounding neurovascular structures. Long-term follow-up (mean, 3.3 years) revealed improvement of most preoperative symptoms. CONCLUSION Open surgery and radical removal of the AC located at the posterior fossa, based on our retrospective analysis, provide very good long-term postoperative results. The suboccipital approach provides a good and safe exposure of vascular structures and cranial nerves in the CPA and allows radical resection of the cyst, reducing the chance of recurrence.

Management of vestibular schwannomas (acoustic neuromas): the value of neurophysiology for evaluation and prediction of auditory function in 420 cases.

OBJECTIVE: From 1978 to 1993, 1000 vestibular schwannomas were operated on at the Department of Neurosurgery at Nordstadt Hospital. The goal was to improve the changes of hearing preservation by recording auditory brain stem responses (ABRs). ABRs can be used for preoperative classification of cochlear nerve impairment and for prediction of the changes of hearing preservation. PATIENTS AND METHODS: In addition to the previously described audiometric testing, the patients underwent perioperative and intraoperative bilateral ABR recording at 100-dB condensation and rarefaction click stimulation. The classification system of five types of ABRs, as presented before, is based on the presence and on the latencies of Waves I, III, and V, with a special emphasis on Wave IIIs representing the activity of the first brain stem nuclei within the auditory pathway. According to an analysis of 420 preoperative ABRs, in case of a preoperative Type 1 or 2, the rate of hearing preservation is 80%. DISCUSSION: In the case of good clinical and audiometric hearing, a severely deteriorated ABR is mostly an indicator of severe nerve compression and adhesion by the tumor. In view of subsequently reported experiences with intraoperative ABR monitoring, the value of the presented system emphasizing the importance of Wave III is stressed and discussed with other views in the literature. The criteria presented here are not designed for recognition of retrocochlear disease but aim for evaluation of the state of the auditory nerve and its perspective. CONCLUSION: By the presented classification of ABR Types B1 through B5, preoperative prediction of the likelihood of hearing preservation is improved.