Biomedical subjects

M Samii

Publications and source records attributed to M Samii.

At least 127 records · Page 7Linked to original sources

PubMed1998

Microvascular decompression for superior oblique myokymia: first experience. Case report.

Superior oblique myokymia (SOM) is a rare eye movement disorder presenting as uniocular rotatory microtremor due to intermittent contractions of the superior oblique muscle. Medical treatment usually fails to provide long-term benefit for the patient and has considerable side effects. Surgical alternatives including tenotomy or partial tenectomy of the superior oblique tendon often result in incomplete resolution of the visual symptoms. The authors report a patient who experienced immediate cessation of disabling SOM following microvascular decompression of the fourth nerve at the root exit zone. Temporary double vision at downgaze resolved 5 months after surgery. There was no recurrence of oscillopsia during a follow-up of 22 months to date. From this single observation it appears likely that vascular compression of the trochlear nerve could be a significant pathophysiological factor contributing to SOM. In the hands of an experienced surgeon, microvascular decompression at the brainstem exit zone of this nerve may evolve as the method of choice for selected cases of disabling SOM.

Decompression↗

PubMed1998

Dopaminergic graft-induced long-term recovery of complex sensorimotor behaviors in a rat model of Parkinson's disease.

Transplantation of embryonic dopamine neurons has evolved as an alternative neurosurgical treatment strategy for patients with Parkinson's disease and it is therefore of great interest to further optimise this procedure in experimental studies. We have applied a modified microtransplantation approach in unilaterally 6-hydroxydopamine lesioned rats and observed a substantial and long-lasting functional recovery in complex spontaneous behaviors, such as skilled forelimb use and stepping behavior. The results demonstrate that the rat model of Parkinson's disease is a highly useful tool to study mechanisms of neural plasticity and regeneration. The ability of dopaminergic grafts to restore complex sensorimotor behaviors in animals also indicate their great potential for the development of a successful clinical application.

Animals↗

PubMed1997

Hemispheric asymmetries in spontaneous firing characteristics of substantia nigra pars reticulata neurons following a unilateral 6-hydroxydopamine lesion of the rat nigrostriatal pathway.

Single unit activity of substantia nigra pars reticulata (SNR) neurons was recorded bilaterally in rats subjected to unilateral 6-hydroxydopamine lesions of the ascending mesostriatal dopaminergic pathway, resulting in an almost complete loss of dopaminergic neurons in the ipsilateral SN pars compacta. Firing rate and firing pattern of SNR neurons in lesioned rats were compared with respective data from sham-lesioned rats and naive controls. In lesioned rats, the mean firing rate of SNR neurons at the lesioned side was significantly reduced and there was an increase in the occurrence of bursting activity. In contrast, firing rate in the contralateral SNR was significantly increased without change in the frequency of bursting neurons. This asymmetrical change in spontaneous firing characteristics of SNR neurons following the lesion could be involved in the complex behavioral changes seen in this model of Parkinson's disease.

Animals↗

PubMed1997

[Diagnosis and surgical indications of traumatic brachial plexus lesions from the neurosurgery viewpoint].

The precise preoperative clinical and electrophysiological evaluation of the brachial plexus as well as an exact radiological evaluation are the keystones for the treatment of traumatic injuries of the brachial plexus. Furthermore, surgical management and prognosis of traction injuries of the brachial plexus depend on the accurate diagnosis of root avulsion from the spinal cord. Myelography, myelo-computed tomography and recently magnetic resonance imaging are the main radiological methods for preoperative diagnose of cervical root avulsions. Surgical experience shows that in may cases, extraspinal findings diverge from intradural findings. Consequently, only correlation with the intradural surgical findings will allow us to define the factual accuracy of myelo-CT and MRI studies. Accuracy of the preoperative myelo-CT based diagnosis related to the intraoperative intradural findings was 85% On the other hand, MRI showed an accuracy of only 52%. Therefore, myelo-CT scans with 1 to 3 mm axial slices proves to be the most reliable method to evaluate preoperatively the presence of complete or partial root avulsion in traumatic brachial plexus injuries. However in 15% of the cases preoperative exact radiological diagnosis is unfortunately not reliable. In these special cases intraspinal surgical exposure of the cervical roots will provide the accurate diagnosis of root avulsion. Accurate clinical evaluation and exact assessment of intraspinal root avulsion simplify enormously the decision concerning the choice of donor nerves for transplantation and/or neurotization during brachial plexus surgery.

Brachial Plexus↗

PubMed1997

[Nerve transfer (neurotization) for functional reconstruction of arm functions in cervical root avulsions].

Neurotization procedures represent an important therapeutic option in patients with complete root avulsion due to traumatic brachial plexus injuries. A variety of normal donor nerves can be used, including intercostal nerves, accessory nerve, parts of the cervical plexus, phrenic nerve, and/or the contralateral C7 nerve root. The reconstructive neurotization procedure should be performed within 3-6 months following the trauma and, when successful, can lead to substantial improvement in motor function for the shoulder and upper arm and in sensory function for the forearm, hand and finger region. Neurotization can also be combined with neurolysis and/or transplantation to restore upper limb motor and sensory function in order to achieve greater therapeutic benefit for patients with posttraumatic brachial plexus lesions.

Arm↗

PubMed1997

[Nerve transplantation and neurolysis of the brachial plexus after post-traumatic lesions].

Autologous transplantation in brachial plexus injuries has become significantly more efficacious through increased knowledge of the microtopographic anatomy of the fascicle structures and the refinement of microneurosurgical techniques. Recovery of shoulder and upper arm functions can be achieved with autologous transplantation in the majority of patients under optimized conditions. However, attempts to restore forearm, hand and finger functions in this way have been disappointing so far. Therapeutic success is primarily governed by early decision making, selection of adequate surgical strategies and intensive and longlasting postoperative management.

Arm↗

PubMed1997

[Pain management after post-traumatic brachial plexus lesions. Conservative and surgical therapy possibilities].

The occurrence of sever pain is one of the most disabling symptoms after the traumatic lesion of the brachial plexus. Avulsion of one or more cervical roots of the brachial plexus is the main cause of severe pain, known as deafferentation pain. Lesion of the dorsal horn of the cervical spinal cord due to root avulsion may lead to important pathological changes and scarring that are responsible for the induction of pain sensations. Different medical and surgical treatment modalities have been established to relief such pain after brachial plexus injury. In contrast to drug therapy, which usually offers only limited benefit, surgical treatment over the last years has shown positive results. Coagulation of the dorsal root entry zone (DREZ) is one of the most efficient surgical treatments for these patients. Understanding of the pathophysiological changes and different pain mechanisms induced by traumatic injury of the brachial plexus is fundamental for the planning and step-wise treatment of such patients.

Brachial Plexus↗

PubMed1997

Accuracy of single-energy quantitative computed tomography in the assessment of bone mineral density of cervical vertebrae.

Earlier studies have shown that single-energy quantitative computed tomography (SEQCT) is a reliable method for bone mineral density (BMD) measurements in thoracic and lumbar vertebrae. Moreover, SEQCT has proved to be a useful parameter in the selection of appropriate implants in cervical spondylodesis. The aim of this study was to determine the accuracy of SEQCT in cervical vertebrae BMD measurement. BMD with reference to calcium hydroxyapatite (Ca10[PO4]6[OH]2) was assessed by SEQCT in 100 human vertebral bodies of the cervical spine. Bone cylinders were then cut from the appropriate region of interest. The cylinder volume was determined by the liquid displacement technique. The density of the mineral component was measured following incineration at 1100 degrees C for 24 h. The calculated BMD was correlated with the SEQCT values, resulting in a coefficient of r = 0.79 (P < 0.01). Mean SEQCT values were significantly lower than those determined by direct density assessment (t-test for coupled sampling, P < 0.02). This result was in agreement with studies on thoracic and lumbar vertebrae. These data suggest that SEQCT can reliably measure BMD in the cervical spine.

Bone Density↗

PubMed1997

Dynamic properties of lymphatic pathways for the absorption of cerebrospinal fluid.

To study the dynamics of the outflow of cerebrospinal fluid (CSF) into the cervical lymphatic system, X-ray contrast medium or Indian ink was infused into the cisterna magna of rats at moderately increased intracranial pressure (40-50 mmHg). In the first series of experiments, while the contrast medium was being infused, the animal's head was examined using X-ray-microscopy (x4-20 direct magnification radiography) and conventional radiography. Within the first minutes of infusion, the flow of CSF was directed from the posterior fossa to the olfactory bulb. Reaching the cribriform plate approximately 7 min after starting the infusion, the contrast medium leaked into the nasal cavities. Some minutes later, it opacified the subarachnoid space (SAS) of the optic nerve, the perilymphatic space of the inner ear, the cortical SAS, and the transverse sinuses. Leakage from the optic nerve SAS into the orbit was seen after 30 min infusion. In the second series of experiments, the Indian ink was infused after microsurgical exposure of the cervical lymph vessels. During the infusion the cervical lymph ducts were observed microscopically (x40 magnification). Single dye particles draining through the cervical lymph ducts appeared 20 min after the start of cisternal infusion. Their transport was rapid, and dependent on the respiratory cycle: during inspiration the particles moved at a speed of 10-20 mm/s, during expiration the movement stopped. Thus, rapid kinetics are demonstrated for the outflow of CSF and particles from the SAS into the cervical lymphatics.

Animals↗

PubMed1997

Breakdown of the meningeal barrier surrounding the intraorbital optic nerve after experimental subarachnoid hemorrhage.

PURPOSE: The intraorbital optic nerve sheath meninges contain a perineural subarachnoid space lined by meningeal cell layers and intercellular fibrous tissue. We sought to determine whether functional or structural characteristics, or both, of the optic nerve sheath are influenced by the increased intracranial pressure after the rupture of cerebral aneurysms. METHODS: We infused the great cisterns of cats with either x-ray contrast medium or autologous blood. The cisternal infusions were done under the experimental condition of a sudden 2.5-minute increase in intracranial pressure similar to that recorded after the rupture of cerebral aneurysms in humans. RESULTS: Digital subtraction radiographs of the optic nerves taken during the cisternal infusion of contrast medium at the start showed the opacification of the optic nerve subarachnoid space. After 2 minutes, the contrast medium leaked into the orbit, indicating the breakdown of the meningeal fluid barrier. Ultrastructural investigation of the optic nerve sheath after high-pressure cisternal infusions showed the arachnoid cell layers scattered. The flattened arachnoid cells displayed mainly intracellular and some intercellular, porelike openings. After infusion of blood into the great cistern, erythrocytes were found within porelike openings of the arachnoid cells. CONCLUSIONS: The meningeal fluid barrier of the optic nerve sheath can be destroyed by pressure changes associated with subarachnoid hemorrhage. This disruption might be regarded as a natural optic nerve sheath fenestration that allows outflow of cerebrospinal fluid into the orbit to protect the optic nerve from increased intracranial pressure after aneurysmal rupture.

Angiography, Digital Subtraction↗

PubMed1997

Cystic meningiomas resembling glial tumors.

BACKGROUND: Meningiomas can be associated with peripheral or intratumoral cysts. Meningiomas with intratumoral cysts, also called "true cystic" meningiomas, are rare and can frequently be confused with glial or metastatic tumors. METHODS: We report three cases of "true cystic" meningiomas and discuss the preoperative evaluation, etiology, and surgical treatment of these cystic lesions with reference to the literature. RESULTS: Magnetic resonance imaging (MRI) and computed tomography (CT) studies usually display a cystic lesion close to the dura with or without enhancement of the cyst wall. Multiplanar MRI scans are very useful to show the presence of a solid tumor or some dural enhancement. Some cases of "true cystic" meningiomas however, are still erroneously preoperatively diagnosed. Complete surgical removal of the tumors and of the entire cyst wall was performed in our cases. Despite the absence of a typical ring enhancement of the cystic lesion in two cases, histopathologic studies displayed the presence of tumor cells on the cyst wall of both cases. CONCLUSIONS: Tumor cells can be present on the cyst wall and therefore can be one of the causes of tumor recurrence if not totally removed. Accurate preoperative radiologic diagnosis (multiplanar MR images) and intraoperative histopathologic studies are fundamental in that they will definitely influence the surgical strategy and outcome.

Adult↗

PubMed1997

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.

Adult↗

PubMed1997

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 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%.

Cranial Nerve Diseases↗

PubMed1997

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.

Audiometry, Pure-Tone↗

PubMed1997

Management of vestibular schwannomas (acoustic neuromas): the value of neurophysiology for intraoperative monitoring of auditory function in 200 cases.

OBJECTIVE: The present study investigated the significance of the presence or absence of auditory brain stem response (ABR) Waves I, III, and V as functional representatives of the cochlea, the nucleus cochlearis, and the colliculus inferior, respectively, and attempted to identify the microsurgical maneuvers that were especially likely to cause isolated or combined component losses and subsequent hearing losses. METHODS: Based on the previously described ABR classification system, 201 patients with preserved Waves I, III, and V or Waves I and V were investigated for the peak latencies and amplitudes of the waves at 15 defined microsurgical stages. Analysis was performed with respect to the presence or absence of ABR components during specific microsurgical actions and the related danger of deafness. RESULTS: Temporary or permanent losses of Waves V, I, and III occurred with 21, 27, and 29% of surgical actions, respectively, leading to deafness in 65 to 78% of the patients. Wave III disappearance was identified as the earliest and most sensitive sign. Wave V loss was usually preceded by disappearances of Waves I and III. During the most dangerous actions (drilling, pulling downward, medially, or laterally, and direct nerve manipulation), special attention ws paid to deterioration of Wave-III and then Wave I; if impairment was seen, intermittent breaks or changes in the type or site of microsurgical action were used to enable wave recovery. Acute, simultaneous, and permanent loss of all waves occurred in 27.5% of postoperatively deaf patients, whereas stepwise wave deterioration and losses occurred in 72.5%. CONCLUSION: Useful (in-time) recognition of significant waveform changes is possible and enables a change of microsurgical maneuvers to favor ABR recovery.

Audiometry, Pure-Tone↗

PubMed1997

Management of vestibular schwannomas (acoustic neuromas): radiological features in 202 cases--their value for diagnosis and their predictive importance.

OBJECTIVE: Tumor-induced bony and soft tissue findings might reflect, in part, the biological characteristics of vestibular schwannomas and could predict clinical findings. In addition, the role of the individual anatomic conditions of the posterior fossa is of interest to the surgeon. METHODS: Of 1000 vestibular schwannomas treated surgically at the neurosurgical department at Nordstadt Hospital, 202 cases, which were consecutively investigated at the same computed tomography (CT) unit and using the same technique (high-resolution CT at bone windows before and after surgery, contrast-enhanced high-resolution CT before surgery, and native high-resolution CT after surgery), were evaluated for special radiological features. Evaluation included, in 103 cases, anatomic parameters of the petrous bone and posterior fossa cavity and, in 202 cases, tumor-induced changes of bony structures, tumor relations with bony structures and with neural structures, and postoperative findings of bony structures and of neural tissues. These radiological parameters and the related clinical pre- and postoperative findings were transferred to a database for statistical evaluation of their positive or negative correlations, i.e., for their reliability in diagnosis and their importance in predicting postsurgical outcome. RESULTS: As important parameters, the following could be identified. The length of the posterior auditory canal wall and the interear difference of the maximum porus width both correlate with the degree of preoperative hearing deterioration (P < 0.05). The extent of the widening of the internal auditory canal is of predictive importance for the chances of postoperative hearing preservation or hearing loss (P < 0.01). The extent of tumor growth anterior and caudal to the internal auditory canal in large tumors is of significant importance for prediction of postoperative hearing function (P < 0.05). The tumor extension in all directions and the extent of cystic tumor components correlate with the pre- and postoperative function of the facial and cochlear nerves. The positions of the labyrinthine structures and their geographical relations to the fundus and the sigmoid sinus and, thereby, to the suboccipital route, enable reliable calculations of the danger of labyrinthine destruction and help improve the planning of the surgical strategy. DISCUSSION AND CONCLUSIONS: In addition to the importance for surgical planning, preoperative bone window CT and contrast-enhanced images offer the opportunity to identify traits of tumor biology, such as bony destruction of the internal auditory canal, tumor shape and cyst formation, and aspects with predictive importance for postoperative outcome. The average size for hearing preservation in tumors was 14.5 x 16.5 x 11.8 mm (coronal x sagittal x axial). The recent finding (8) of a higher presentation age in female patients has an apparently anatomic basis, which is a relatively larger internal auditory meatus.

Brain↗

PubMed1997

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.

Adolescent↗

PubMed1997

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.

Adolescent↗