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ABSTRACT: To obtain information on functional integrity of the facial nerve by transcranial electrical motor evoked potentials independent of nerve visualization and to improve prediction of postoperative function.
In a prospective clinical study, 68 patients with cerebello-pontine angle tumors and 5 patients with trigeminal neuralgia were investigated by facial motor evoked potentials (FMEP) elicited by multi-pulse transcranial electrical motor cortex stimulation. For recording the same electrode set-up was used as for continuous EMG monitoring of the orbicularis oculi and oris muscles. Pre-surgical FMEP amplitudes and latencies were correlated with tumor extensions. End to start amplitude ratios were compared to early and long-term facial nerve function by House-Brackmann-Grading (HB) documented by pre- and post-operative photo and video documentation.
Reliable FMEP were obtained in 57 patients. FMEP responses at the start of surgery correlated with the degree of tumor extension. Largest FMEP amplitudes and shortest latencies were found in patients with trigeminal neuralgia. FMEP quality was reduced with increasing tumor extension (P<0.05). The ratio of end-operative to start-operative FMEP-amplitude showed a positive correlation with early and late facial nerve function. Correlation was especially close with early function: an amplitude preservation rate of 86% led to HB°1 or HB°2, of 67% to HB°3, at 33% to HB°4 and at 15% or lower to HB°5 or HB°6.
Initial FMEP amplitudes correlate with the presumed pre-operative nerve affection by space occupying tumors, a phenomenon reported here for the first time. Intact FMEP are highly reliable for preserved nerve continuity and hereby are of special help to the neurosurgeon for those surgical phases where the facial nerve is not visible and still covered by tumor and where conventional EMG monitoring is of very limited use. The end-to-start amplitude ratio of the FMEP is closely related to early and late clinical function. Amplitude reduction by 30% or more should result in a change of microsurgical action to enable fast recovery.
As an adjunct to intraoperative EMG, FMEP are superior in two respects, first in identifying pre-surgical latent nerve lesions and second in monitoring nerve integrity without direct nerve visualization. FMEP are highly reliable in predicting early and late postoperative function.
Clinical neurology and neurosurgery 07/2011; 113(10):872-9. · 1.30 Impact Factor
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Thomas Westermaier,
Christian Stetter,
Giles H Vince,
Mirko Pham,
Jose Perez Tejon,
Jörg Eriskat,
Ekkehard Kunze, Cordula Matthies,
Ralf-Ingo Ernestus,
Laszlo Solymosi,
Klaus Roosen
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ABSTRACT: 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.
Prospective, randomized, placebo-controlled study.
Neurosurgical intensive care unit of a University hospital.
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.
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.
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.
Critical care medicine 03/2010; 38(5):1284-90. · 6.37 Impact Factor
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ABSTRACT: Trigeminal neuralgia in Chiari's type I malformation is rare and remains a therapeutic challenge. We report a case of bilateral trigeminal neuralgia in Chiari's type I malformation. This case demonstrates that microvascular decompression can be an effective treatment strategy for this complex pathology.
British Journal of Neurosurgery 03/2010; 24(4):474-6. · 0.88 Impact Factor
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ABSTRACT: The inferior colliculus (IC) is an alternative site for electrode placement in neural deafness due to its surgical accessibility and its well-known tonotopic stratification. In patients where tumor surgery has already occurred and the cerebellopontine angle contains scar tissue or tumor-remnants, midline and paramedian supracerebellar approaches are alternative routes. They are often avoided due to concerns regarding the venous drainage of the cerebellum, the electrode trajectory and the course of the electrode cable. We studied these surgical routes in five neuronavigated fixed cadaveric specimens. For paramedian and midline approaches, the transverse sinus was exposed 5.8mm on average. A mean of 1.6 cerebellar veins, with an average diameter of 2.0mm, draining to the tentorium were transected to reach the tentorial notch. Only 0.4 arterial branches were met. We conclude that the supracerebellar midline and paramedian approaches provide a good exposure of the IC and offer safe and viable alternative routes to the IC. Additionally, they provide a wider angle of action for optimal electrode placement.
Journal of Clinical Neuroscience 12/2009; 17(1):107-12. · 1.25 Impact Factor
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ABSTRACT: Arachnoid cysts are frequent anomalies of the CNS. They are benign lesions within the arachnoid membrane and have been reported to occur in virtually all locations where arachnoid is present. An intraventricular location, however, is rare and occurrence within the fourth ventricle is particularly uncommon. The first report was published in 1979 on a paediatric patient. Since then, only a few further examples have been reported. Most of these patients presented with hydrocephalus. Shunting procedures were performed, but did not afford long-term improvement of symptoms. Definitive treatment consisted of open resection of the cyst-wall. We report a 34-year-old woman with a large arachnoid cyst within the fourth ventricle who suffered from progressive cerebellar dysfunction. MRI showed massive enlargement of the fourth ventricle by an intraventricular arachnoid cyst which contained multiple septations. Complete excision of the cyst was necessary to reinstitute free CSF-flow and was performed via a median suboccipital approach. This report gives an overview of examples published to date and discusses pathogenesis and clinical features of arachnoid cysts in this location as well as operative strategies including neuroendoscopic techniques.
Acta Neurochirurgica 05/2009; 152(1):119-24. · 1.52 Impact Factor
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ABSTRACT: The purpose of this study was to provide genetically modified adult human Schwann cells as tools for cell transplantation in peripheral nerve repair. The application of transfected autologous Schwann cells overexpressing regeneration-promoting proteins, for example, neurotrophic or growth factors, is a promising approach in the aforementioned context. To achieve an optimal clinical outcome, it is highly important to perform enrichment, genetic modification, and retransplantation of cells in a short time.
To enable the development of these autologous cellular prostheses, the authors tested the properties of adult human Schwann cells obtained from differently treated human peripheral nerve biopsy samples. The use of "cold jet," a fast and effective enrichment procedure, as well as selective, serum-free culture conditions, resulted in very pure adult human Schwann cell cultures. Using an optimized electroporation protocol, as many as 48.4% of adult human Schwann cells were successfully transfected.
The authors present a very fast protocol to establish adult human Schwann cell cultures that demonstrably express plasmid proteins after plasmid DNA insertion by electroporation. These autologous human Schwann cells transfected to enhance the endogenous production of regeneration-supporting proteins will likely constitute a major component of tissue-engineered peripheral nerve grafts.
Journal of Neurosurgery 06/2006; 104(5):778-86. · 2.96 Impact Factor
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ABSTRACT: Meningiomas of the cerebellopontine angle (CPA) share a common location, but their site of dural origin and their relationship to surrounding neurovascular structures of the CPA are variable. The clinical presentation and outcome after surgical resection are different because of the diversity of this tumor entity. We report on a series of 421 patients with CPA meningiomas, with special emphasis on the analysis of the preoperative and postoperative facial and cochlear nerve function in relation to the site of dural attachment and main tumor location in the CPA cistern.
Among 421 patients, the charts of 347 patients with complete clinical data, including the history and audiograms, imaging studies, surgical records, discharge letters, histological records, and follow-up records, were reviewed retrospectively. Data about preoperative and postoperative facial nerve function were available in 334 patients, and audiometric analysis was conducted in 333 patients. Patients with neurofibromatosis Type 2 were excluded from the study.
There were 270 women and 77 men, with a mean age of 53.4 years (range, 17.6-84 yr). Among these patients, 32.9% of the tumors originated at the petrous ridge anterior to the inner auditory canal (IAC) (Group 1), 22.2% showed involvement of the IAC (Group 2), 20.2% were located superior to the IAC (Group 3), 11.8% were inferior to the IAC (Group 4), and 12.9% were posterior to the IAC, originating between the IAC and the sigmoid sinus (Group 5). Patients presented with disturbance of Cranial Nerves V-VIII, the lower cranial nerves, and ataxia, depending on the main tumor location. Tumor resection was performed through a suboccipital-retrosigmoidal approach in the semisitting position in 95% of the patients. A combined supratentorial-infratentorial presigmoidal approach was performed in 5%. Total tumor removal (Simpson Grade 1 and 2) was achieved in 85.9% and subtotal removal in 14.1%. The best initial postoperative facial and auditory nerve function was observed in tumors belonging to Groups 3 and 5. Recovery from preoperative deafness was observed in 1.8% of patients. On long-term follow-up, good facial nerve function (House-Brackmann Grade 1 or 2) was observed in 88.9% of patients. Hearing preservation among patients with preoperative functional hearing was documented in 90.8% on long-term follow-up.
Although the outcome of facial and cochlear nerve function is different in CPA meningiomas, depending on the topographic classification of these tumors, preservation of the cochlear nerve is possible in every tumor group and should be attempted in every patient with CPA meningioma. It has to be kept in mind that recovery of hearing was also observed in patients with preoperative profound hearing deficits.
Neurosurgery 08/2005; 57(1):77-90; discussion 77-90. · 2.79 Impact Factor
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ABSTRACT: Meningiomas of the cerebellopontine angle (CPA) can either arise from or secondarily grow into the inner auditory canal (IAC). This location may have a great impact on hearing function following surgery to remove these lesions. The aim of this retrospective study was to investigate the reliability and predictive importance of auditory brainstem responses (ABRs) for the determination of postoperative auditory function in patients with CPA meningiomas in comparison with results obtained in patients who undergo surgery for vestibular schwannomas.
In a consecutive series of 1800 meningiomas surgically treated between 1978 and 2002, 421 lesions were located in the CPA. In 38 patients with CPA meningiomas involving the IAC, the findings of intraoperative ABR monitoring and the hearing status of each patient before and after surgery were retrospectively analyzed. On analysis, ABR monitoring demonstrated stable findings in 24 patients throughout tumor resection and fluctuating signals in 10 patients. Among the 24 patients with stable ABRs, postoperative hearing function improved in three patients, remained the same in 15, and worsened in six patients, including one patient who displayed postoperative deafness. There was even one patient recovering from preoperative deafness. Among the 10 patients with unstable ABRs, intermittent decreases in amplitude and deformations of variable duration in the ABR wave were noted. The risk of deafness was considerably higher in patients with prolonged phases of intermittent ABR deterioration.
The presence and absence of ABRs during surgery for CPA meningiomas reliably predicted the presence and absence of postoperative auditory function. Intermittent deterioration of ABRs may result in postoperative deafness, depending on the duration of these events during surgery. Improvements in hearing are only seen when the ABRs are stable for amplitudes and latencies throughout surgery.
Journal of Neurosurgery 05/2005; 102(4):637-42. · 2.96 Impact Factor
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ABSTRACT: Only some meningiomas of the cerebellopontine angle (CPA) extend into the internal auditory canal (IAC) or arise from its dural lining. The authors investigated cases of CPA tumors in which the meningioma was inserted in the dura mater in or at the ICA or infiltrated a cranial nerve.
The authors reviewed patient charts including surgical and clinical records, intraoperative recordings of auditory evoked potentials, records of postoperative auditory examinations, and imaging studies. In a series of 421 patients harboring CPA meningiomas, 72 patients in whom there was dural involvement of the IAC were investigated. Total tumor resection was achieved in 86.1%. In 34 patients, opening of the IAC was required for total tumor removal; this procedure did not influence the patient functional outcome. Among patients with secondary involvement of the IAC, anatomical preservation of the facial and cochlear nerves was obtained in 94%, whereas among patients in whom the lesion arose from the dura in or at the IAC these values were 80 and 75%, respectively. Functional preservation of the seventh and eighth cranial nerves in cases of tumor extension within the IAC was 86 and 77%, respectively, whereas in cases in which the IAC was involved it was only 60%. In four of five patients in whom the tumor had its origin in the dura mater within the IAC, the seventh or eighth cranial nerve had to be sacrificed to achieve tumor removal because of the lesion's infiltrative behavior. Facial nerve reconstruction by sural grafting was performed in the same operative procedure.
Meningiomas of the CPA involving the IAC require special surgical management. Dural involvement of the IAC requires opening by using a diamond drill, a procedure that does not influence cranial nerve outcome. The increased rate of cranial nerve morbidity is attributed to the infiltrative behavior of these meningiomas. If affected nerve segments have to be sacrificed, immediate reconstruction enables satisfactory long-term results.
Journal of Neurosurgery 02/2005; 102(1):17-23. · 2.96 Impact Factor
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ABSTRACT: Meningiomas arising primarily within the internal auditory canal (IAC) are notably rare. By far the most common tumors that are encountered in this region are neuromas. We report a series of eight patients with meningiomas of the IAC, analyzing the clinical presentations, surgical management strategies, and clinical outcomes.
The charts of the patients, including histories and audiograms, imaging studies, surgical records, discharge letters, histological records, and follow-up records, were reviewed.
One thousand eight hundred meningiomas were operated on between 1978 and 2002 at the Neurosurgical Department of Nordstadt Hospital. Among them, there were 421 cerebellopontine angle meningiomas; 7 of these (1.7% of cerebellopontine angle meningiomas) were limited to the IAC. One additional patient underwent surgery at the Neurosurgical Department of the International Neuroscience Institute, where a total of 21 cerebellopontine angle meningiomas were treated surgically from 2001 to 2003. As a comparison, the incidence of intrameatal vestibular schwannomas during the same period, 1978 to 2002, was 168 of 2400 (7%). There were five women and three men, and the mean age was 49.3 years (range, 27-59 yr). Most patients had signs and symptoms of vestibulocochlear nerve disturbance at presentation. One patient had sought treatment previously for total hearing loss before surgery. No patient had a facial paresis at presentation. The neuroradiological workup revealed a homogeneously contrast-enhancing tumor on magnetic resonance imaging in all patients with hypointense or isointense signal intensity on T1- and T2-weighted images. Some intrameatal meningiomas showed broad attachment, and some showed a dural tail at the porus. In all patients, the tumor was removed through the lateral suboccipital retrosigmoid approach with drilling of the posterior wall of the IAC. Total removal was achieved in all cases. Severe infiltration of the facial and vestibulocochlear nerve was encountered in two patients. There was no operative mortality. Hearing was preserved in five of seven patients; one patient was deaf before surgery. Postoperative facial weakness was encountered temporarily in one patient.
Although intrameatal meningiomas are quite rare, they must be considered in the differential diagnosis of intrameatal mass lesions. The clinical symptoms are very similar to those of vestibular schwannomas. A radiological differentiation from vestibular schwannomas is not always possible. Surgical removal of intrameatal meningiomas should aim at wide excision, including involved dura and bone, to prevent recurrences. The variation in the anatomy of the faciocochlear nerve bundle in relation to the tumor has to be kept in mind, and preservation of these structures should be the goal in every case.
Neurosurgery 08/2004; 55(1):119-27; discussion 127-8. · 2.79 Impact Factor
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ABSTRACT: Suramin inhibits tumour growth and neoangiogenesis by blocking several growth factor receptors. In this study the toxicity and efficacy of intralesional delivery of suramin incorporated in a controlled-release polymer were assessed in a rat 9L tumour model. Initially, the toxicity of the compound was evaluated in adult Fisher 344 rats. The animals were intracerebrally implanted with an ethylene vinyl acetate copolymer. These experiments showed early toxicity in the rats implanted with a 50% load-polymer and 100% mortality within 48 h, whereas in rats implanted with a 33% load-polymer only transient behavioural changes were observed. In a second experiment the rats were stereotactically implanted with 9L cells in the frontal region. Two days after inoculation of cells, the animals were divided into two groups: one group received a 33% suramin load-biopolymer at the tumour implantation site, while the control group received polymer implants only. The interstitial release of suramin in the brain did not produce any improvement in survival of 9L tumour-bearing rats, with a mean survival of 14.2 +/- 1 days for the suramin-treated group versus 13.8 +/- 2 for the control group (p = 0.82). We conclude that intralesional polymer-mediated chemotherapy with suramin does not prolong survival in rats with intracerebral 9L tumours.
Acta Oncologica 02/2004; 43(3):259-63. · 3.33 Impact Factor
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ABSTRACT: To highlight the clinical, radiological, and surgical findings and therapeutic options for this rare entity, which may mimic a purely intrameatal vestibular schwannoma, and to define the particular aspects of preoperative differential diagnosis and surgical management.
Two patients presented with clinical findings typical of vestibular schwannomas, i.e., tinnitus, hearing loss of 30 dB, and an intrameatal contrast-enhancing lesion on magnetic resonance imaging studies.
The lesions were exposed via a suboccipital transmeatal approach, and tumor infiltration of the cochlear and/or facial cranial nerves was identified. In view of the unclear intraoperative histology, surgical management was based on criteria of cranial nerve function. In Patient 1, after nerve decompression by subtotal tumor removal, preserved auditory brainstem responses and facial nerve electromyography indicated functional nerve preservation and facilitated the decision for partial resection. In Patient 2, minimal tumor dissection resulted in complete loss of auditory brainstem response without reversibility. Therefore, a radical tumor removal was performed that sacrificed the cochlear but preserved the facial nerve.
Symptoms and signs of internal auditory canal hamartomas are congruent with other typical pathological lesions of the internal auditory canal and cerebellopontine angle. Accurate preoperative diagnosis by radiological means is not possible, but careful evaluation of the different signal intensities on magnetic resonance imaging studies may indicate this rare pathological condition. Intraoperative surgical findings of tumor infiltration of the faciocochlear cranial nerve complex may support simple observation. In view of the nonneoplastic characteristic of these lesions, a more conservative approach is justified. The decision should be based on the functional status of the cranial nerves, for which reliable electrophysiological monitoring is indispensable.
Neurosurgery 05/2003; 52(4):944-8; discussion 948-9. · 2.79 Impact Factor
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ABSTRACT: OBJECTIVE The purpose of this study was to present the patients' recommendations and judgments about their hearing and communication abilities with the help of the auditory brainstem implant.
Prospective study.
Tertiary referral center.
This evaluation was based on the data obtained by the self-administered questionnaires designed for the European Auditory Brainstem Implant Multicenter Clinical Trial. Eleven patients who had used their auditory brainstem implant for a minimum of 6 months to a maximum of 41 months were evaluated with the help of these questionnaires.
All the patients had used their implant on a regular daily basis for an average of 13 hours per day. None of them experienced any side effects during the daily use of the device. Nine patients (82%) used their auditory brainstem implant in both quiet and noisy surroundings. The most common cause of disturbance was a noisy surrounding. All the patients were able to distinguish speech from environmental sounds. The role of the auditory brainstem implant in differentiating various environmental sounds was considered to be very useful by 9 patients (82%). As an adjuvant to lip-reading, the auditory brainstem implant was considered most useful for understanding speech in quiet surroundings.
It was concluded that the auditory brainstem implant is an effective support for receiving and, to some degree, differentiating environmental sounds, and that as an adjuvant to lip-reading, it enhances speech perception, especially in quiet surroundings. A comparison between the results of this study and the results of the audiologic tests presented in Part I of this study (published earlier) revealed that patient satisfaction was not directly correlated with the results of the objective auditory tests. In general, patients' judgments of their individual hearing and communication abilities usually rated higher than could have been predicted by the objective audiometric data.
Ontology & Neurotology 10/2002; 23(5):694-7. · 1.90 Impact Factor
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Neurosurgery 10/1998; 43(5):1246. · 2.79 Impact Factor
