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ABSTRACT: Ephaptic transmission is one of the electrophysiological hallmarks of hemifacial spasm. It is generally accepted that in the majority of patients with idiopathic hemifacial spasm, microvascular compression of the facial nerve at the site where the nerve exits the brain stem is the underlying cause. Whether the actual site of the ephapse is at the site of the lesion or at a nuclear level due to hyperexcitability of the facial motor nucleus is still controversial. Rarely, hemifacial spasm may be due to space occupying lesions in the cerebellopontine angle or in the brain stem. We report the electrophysiological findings of four patients with hemifacial spasm due to extra-axial tumors in different locations of the posterior fossa. The location of the tumor was intrameatal in one patient, in the cerebellopontine angle in two patients and in the brain stem in another patient. Facial nerve motor neurographies including transcranial magnetic stimulation revealed abnormal findings in two patients. Selective stimulation of facial nerve branches demonstrated delayed (ephaptic) responses in all but one patient whose hemifacial spasm had disappeared after treatment with carbamazepine. The latencies of the delayed responses did not correlate with the tumor location. In sum, the site of ephaptic transmission cannot be reliably determined by latency measurements of the delayed response because of its variability which is probably caused by the different size and diameter of the axons participating in ephaptic transmission as well as by the extent of focal demyelination at the site of the lesion. A neuroradiological work up including MR imaging should be mandatory in all patients with hemifacial spasm because electrophysiological studies fail to differentiate between idiopathic and symptomatic hemifacial spasm.
Clinical Neurology and Neurosurgery 07/1998; 100(2):104-11. · 1.58 Impact Factor
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ABSTRACT: Cervical dystonia was associated with posterior fossa tumors in three patients. The onset of dystonia paralleled the appearance of other focal neurologic signs. All patients had extraaxial tumors located in the cerebellopontine angle that were removed via suboccipital approaches. The tumors were identified as schwannomas arising from the glossopharyngeal nerve and from the vagus/accessory nerves; and a meningioma. Postoperatively, the cervical dystonia improved markedly during a period of 8 years in one patient, and it remitted completely within 1 year in another patient. In the third patient, cervical dystonia persisted. The combination of the clinical findings and the temporal relationship of their appearance suggest a causal association between the posterior fossa tumors and cervical dystonia in three cases. Possible pathogenic mechanisms are reviewed.
Movement Disorders 06/1997; 12(3):443-7. · 4.51 Impact Factor
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ABSTRACT: We investigated the effect of periventricular and deep white matter lesions (DWMLs) on outcome after cerebrospinal fluid shunting in a prospective series of elderly patients with idiopathic normal-pressure hydrocephalus.
White matter lesions were assessed with T2-weighted magnetic resonance scans according to a standard protocol in 41 patients with idiopathic normal-pressure hydrocephalus of the elderly who underwent subsequent shunting. In all patients, the diagnosis of idiopathic normal-pressure hydrocephalus had been established preoperatively by clinical and diagnostic investigations.
At a mean follow-up of 16 months, clinical improvement was observed in 37 of 41 patients (90%). There was no persistent morbidity related to surgery. The degree of overall clinical improvement was negatively correlated with the extension of periventricular lesions (correlation coefficient r = -0.324 [P = 0.04]) and DWMLs (correlation coefficient r = -0.373 [P = 0.02]). This negative correlation was also noted when the analysis was conducted separately for each of the cardinal symptoms (gait disturbance, cognitive impairment, and urinary incontinence). There was no consistent pattern of periventricular and DWMLs in the four patients who failed to respond to shunting.
Periventricular and DWMLs of varying degrees are common findings on magnetic resonance scans of patients with idiopathic normal-pressure hydrocephalus of the elderly. After careful preoperative selection of patients with idiopathic normal-pressure hydrocephalus, individuals with DWMLs suggestive of concomitant vascular encephalopathy may also benefit from cerebrospinal fluid diversion. Although, in general, the degree of improvement depends on the severity of periventricular and DWMLs, patients with more extensive WMLs still may derive clinical benefit from the operation.
Neurosurgery 09/1996; 39(2):292-9; discussion 299-300. · 2.79 Impact Factor
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ABSTRACT: The authors report their experiences gained from 19 patients with ventral or ventrolateral foramen magnum meningiomas operated on via the dorsolateral, suboccipital transcondylar access route. It is emphasized that the microsurgical management of these lesions includes two important aspects which increase the safety of the procedure: a meticulous preoperative planning based on the microanatomical details of each patient, as well as an individualized tailoring of the surgical approach. There were no deaths, and, in the past 5 years, no neurological complications in this series. Gross total removal of the tumour was achieved in each case. It is concluded that microsurgical removal of ventral or ventrolateral foramen magnum meningiomas with this technique constitutes a safe and recommendable procedure.
Acta neurochirurgica. Supplement 02/1996; 65:82-5.
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ABSTRACT: The present study investigates evidence of dentatothalamic pathway lesions in nineteen patients with severe kinetic post-traumatic tremor respectively by magnetic resonance imaging (MRI). Kinetic tremor is thought to be characteristic of lesions of the cerebellar outflow. While this hypothesis is supported by experimental data, neuropathological and neuroradiological findings have been limited. The appendicular tremors were unilateral in 13 patients and bilateral in 6, accounting for 25 instances of tremor. The tremor developed after severe head trauma in 18 patients. These patients had evidence of diffuse axonal injury on MRI. Postural and kinetic tremor was present in all patients, and was accompanied by tremor also present at rest in 14 instances. Multiplanar MRI studies were performed on a high-field MRI system operating at 2.0 T in 13 patients and on intermediate-field strength MRI systems in 6 patients according to a standardized protocol. To detect small deposits of hemosiderin after post-traumatic lesions, the protocol included a heavily T2-weighted spin-echo pulse sequence. Lesions of the dentatothalamic pathways were found in 22 instances. The lesions were classified into different types of according to their distribution. A lesion of the dentate nucleus ipsilateral to the tremor (type 1) was found in one instance (4%), lesions involving the ipsilateral predecussational dentatothalamic pathway (type II and III) were found in 14 instances (56%), and lesions involving the contralateral post-decussational course (type IV) in 7 instances (28%). One patient with a mild head trauma had a lesion of the contralateral thalamus. The lesions appeared as hypointense, hyperintense or mixed. Two of three patients with a parkinsonian-like rest tremor had type IV lesions involving the substantia nigra. The nosological concepts of tremors are discussed. 'Midbrain' tremor may have distinct pathoanatomical lesion sites.
Neurological Research 01/1996; 17(6):409-16. · 1.52 Impact Factor
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ABSTRACT: The interpretation of data from continuous monitoring of intracranial pressure (ICP) in patients with suspected normal pressure hydrocephalus (NPH) is the subject of controversy. Despite the fact that overnight ICP monitoring is widely used for the diagnosis of NPH, normative criteria are poorly defined. The present study demonstrates that there is a relationship between the relative frequency, the absolute amplitude, the wavelength and the morphology of B-waves and different sleep stages. Intraventricular intracranial pressure was recorded continuously overnight in 16 patients with suspected normal pressure hydrocephalus. Simultaneous polysomnography was performed to investigate the relation of spontaneous ICP oscillations to different sleep stages. A correlative analysis was done with the data of 13 patients. Three patients were excluded, one who was awake throughout the night and two in whom polysomnography was incomplete due to technical reasons. The mean resting cerebrospinal fluid (CSF) pressure was 12.87 cm CSF. B-waves were observed in the ICP recordings of all patients. They were present for a mean of 72% of the total recording time. The relative frequency of B-waves was higher during REM sleep and sleep stage 2 as compared to wakefulness (87.8% and 83.2% vs. 56. p < 0.05). The absolute amplitude was higher during REM sleep than in wakefulness (9.56 vs. 3.44 cm CSF, p < 0.05). Wavelengths were longer in REM sleep than in wakefulness and stages 1 and 2 (62.4 vs. 42, 40.7 and 44.8 sec, p < 0.05). The morphology of B-waves was also related to different sleep stages. Ramp-type B-waves were associated with REM sleep in six patients, however, were also present in sleep stage 2 in three of them. Knowledge of the relation of spontaneous ICP oscillations to different sleep stages may help to establish physiological foundations and alterations. Furthermore, polysomnography may be useful to avoid erroneous interpretation of ICP recordings due to sleep stage related variability.
Acta Neurochirurgica 02/1995; 136(3-4):195-203. · 1.52 Impact Factor
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ABSTRACT: Although primary treatment of medulloblastoma is now successful in a high percentage of patients, its secondary manifestations still bear a poor prognosis. Thorough studies of secondary manifestations are therefore pivotal to plan therapeutic approaches for the long-term management of medulloblastoma. Here we describe the incidence of secondary tumour manifestations in 66 patients of a single centre who underwent surgery for medulloblastoma between 1975 and 1990. No patient was excluded due to a poor postoperative course. Thirty-five patients showed evidence of secondary tumour growth. Of these, 17 suffered from local recurrence, and 27 developed metastastatic disease. The median latencies for secondary manifestations were 25 months for local recurrence (n = 17), 11 months for spinal metastases (n = 10), 15 months for supratentorial metastases (n = 8), 8 months for subleptomeningeal dissemination (n = 6), and 23 months for systemic metastases (n = 8). Two patients developed primary metastatic spread to the posterior fossa. Of 8 patients with supratentorial metastases, 6 developed fronto-basal lesions. In our patients, 89% of secondary lesions occurred within less than 3 years after primary diagnosis. 85% of patients with extra-axial tumour spread had been treated with a permanent shunt. Radical tumour resection and radiotherapy with 30 Gy to the neuraxis and 20 Gy boost to the posterior fossa was an important prognostic factor in this series. Patients with additional chemotherapy did not benefit significantly from this treatment. We conclude that optimal management of the primary lesions should aim at (i) total resection, (ii) avoid permanent shunting, and (iii) completion of the radiotherapy with inclusion of the medial frontobasal cisterns in the radiotherapeutic regimen. Our analysis suggests that adequate postoperative screening programmes should consist of 3-monthly scans of the neuraxis in the first three postoperative years and 6-monthly scans thereafter.
Acta Neurochirurgica 02/1995; 136(3-4):117-26. · 1.52 Impact Factor
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ABSTRACT: Intracranial neoplasms are an uncommon cause of symptomatic Parkinsonism and rest tremor. We found an incidence of 0.3% in a prospective evaluation of 907 patients with supratentorial tumours. Eight patients with Parkinsonism and rest tremor secondary to supratentorial tumours sparing the basal ganglia are reported. Neuro-imaging revealed compression and distortion of the basal ganglia by large tumours which were identified histopathologically as meningiomas in four patients and as an epidermoid, a fibrillary astrocytoma, an anaplastic oligodendroglioma and a glioblastoma. Six patients underwent tumour removal by craniotomy, in two the histopathology was obtained by stereotactic biopsy. Four patients were free of Parkinsonian symptoms and signs on long-term follow-up. The possible pathophysiological mechanisms involved are discussed. Since some of these patients closely resemble cases of idiopathic Parkinson's disease, and the movement disorder can precede other symptoms and signs or will remain isolated in the further course, the diagnosis of an intracranial neoplasm was generally delayed in these patients. Increased awareness of this rare entity may lead to an earlier diagnosis. Early computed tomography in patients with Parkinsonism might help to detect these patients with a potentially curable cause of their condition.
Acta Neurochirurgica 02/1995; 133(1-2):22-9. · 1.52 Impact Factor
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ABSTRACT: Although recently survival of some medulloblastoma patients increased remarkably, it remains a serious diagnosis in others. In order to predict the postoperative prognosis in patients treated for medulloblastoma, a new staging, scoring and grading system was developed. Sixty-six patients operated on microsurgically between 1975 and 1990 at a single neurosurgical center were fully followed-up. No patient was excluded due to a poor postoperative course. Completion of commonly used radiotherapy protocols was attempted in all patients. Survival of patients was evaluated by the Kaplan-Meier method. The following 5 parameters were selected to define subgroups: patients' age, tumour location and histology, degree of resection and presence or absence of metastases. Patients older than 10 years had a better prognosis than individuals aged 10 or less (p < 0.01), patients with lateral tumours had a better prognosis than patients with midline tumours with brain stem infiltration (p < 0.05), patients with complete tumour resection had a more favourable prognosis than individuals with subtotal (p < 0.01) or partial resection (p < 0.001), patients without metastases at the time of diagnosis had a better prognosis than individuals without such evidence (p < 0.001), patients with the desmoplastic tumour variant had a better prognosis than patients with classical tumour histology (p < 0.01). According to the prognosis of a distinct subgroup, scoring points were distributed which correlated with the degree of inter-subgroup significances. The sum of a single patient's scoring points was called the total score. Based on this score, three groups of prognosis were distinguished.(ABSTRACT TRUNCATED AT 250 WORDS)
Acta Neurochirurgica 02/1995; 132(1-3):59-65. · 1.52 Impact Factor
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ABSTRACT: Although recently survival of some medulloblastoma patients increased remarcably, it remains a serious diagnosis in others. In order to predict the postoperative prognosis in patients treated for medulloblastoma, a new staging, scoring and grading system was developed.Sixty-six patients operated on microsurgically between 1975 and 1990 at a single neurosurgical center were fully followed-up. No patient was excluded due to a poor postoperative course. Completion of commonly used radiotherapy protocols was attempted in all patients. Survival of patients was evaluated by the Kaplan-Meier method.The following 5 parameters were selected to define subgroups: patients' age, tumour location and histology, degree of resection and presence or absence of metastases. Patients older than 10 years had a better prognosis than individuals aged 10 or less (pAccording to the prognosis of a distinct subgroup, scoring points were distributed which correlated with the degree of inter-subgroup significances. The sum of a single patient's scoring points was called the total score. Based on this score, three groups of prognosis were distinguished. The good prognosis group (n=29) showed a significantly better survival (pIt is concluded that this new staging, scoring and grading system is a simple and recommendable prognostic system for all patients treated surgically for medulloblastoma.
Acta Neurochirurgica 01/1995; 132(1):59-65. · 1.52 Impact Factor
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ABSTRACT: The case of a 36-year-old man who sought treatment of right facial myokymia and spastic paretic facial contracture is reported. Computed tomography and magnetic resonance imaging revealed a tumor located in the right cerebellar peduncle and the right dorsal pons bulging into the fourth ventricle. After microsurgical partial resection of the mass, which was verified histologically as an anaplastic glioma, facial myokymia initially ceased. The vermicular rippling movements were less intense upon recurrence and could be controlled by low-dose dexamethasone in the further course, when magnetic resonance imaging showed an interstitial pontine edema after percutaneous radiation therapy. It is assumed that facial myokymia and spastic paretic facial contracture were generated by ectopic activity due to alterations in the microenvironment at the intrapontine portion of the axons of the seventh nerve caused by the compressive effect of the tumor and later by edema.
Neurosurgery 07/1993; 32(6):1031-4. · 2.79 Impact Factor
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ABSTRACT: The utility and reliability of a simple technique for the localization of cerebral convexity lesions are retrospectively analyzed in 83 intracranial procedures. The technique is based on data obtained from preoperative computed tomography (CT) scans, and on a few anthropological landmarks which usually can be identified on both the patient's head and skull radiograms. This method allowed precise placement of small craniotomy flaps (3 to 7 cm in diameter) in 94% of the patients studied. In the remaining, localization errors were corrected either by enlarging the craniotomy opening (3 cases), or by rescanning during the operative procedure (2 cases). Due to its technical simplicity and reliability in the vast majority of cases, the bony landmark method constitutes a recommendable alternative for the localization of convexity lesions, being particularly useful when highly sophisticated equipment is not available.
Neurochirurgia 06/1993; 36(3):81-6.
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ABSTRACT: The unusual case of a ventral brain stem schwannoma located at the entry zone of the hypoglossal nerve in a 49-year-old woman is reported. The diagnosis of a schwannoma was confirmed histologically after partial tumor resection via the dorsolateral, suboccipital, transcondylar approach. Hypotheses for the pathogenesis of intramedullary schwannomas are discussed.
Neurochirurgia 04/1993; 36(2):66-9.
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ABSTRACT: Seventy-three cerebral cavernous angiomas were removed microsurgically from a series of 71 patients between August, 1983 and December, 1989. This retrospective investigation assessed the current indications for surgery and determined the prognosis for patients with cerebral cavernous angioma. There were 38 males and 33 females with a mean age of 37 years. Analysis included clinical presentation and history, neuroradiological findings, indications for surgery, and postoperative course. After an average follow-up period of 15 months, 35 patients were symptom-free, 16 had improved preoperative complaints, six were unchanged, and eight had deteriorated. Microsurgical extirpation of the malformation is indicated in all symptomatic patients where neuroimaging demonstrates the presence of a readily accessible cerebral cavernoma. Surgery is recommended in cases with deep-seated lesions causing massive hemorrhage, repetitive minor bleeding, or significant long-standing and progressive neurological disabilities. Clinically silent cavernomas located in eloquent regions of the brain contraindicate surgery, but should be closely monitored. Patients presenting with convulsions or neurological deficits caused by easily accessible cavernomas of the hemispheres have the best prognosis and a negligible risk for surgical complications. Those with deep-seated lesions of eloquent regions of the brain that have bled or caused sustained neurological disorders face the highest risk for morbidity owing to the surgical intervention, requiring careful preoperative evaluation.
Neurologia medico-chirurgica 09/1992; 32(9):659-66. · 0.61 Impact Factor
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ABSTRACT: We report about our experience with the infratentorial supracerebellar approach in 23 patients operated on for lesions located in the posterior part of the third ventricle, quadrigeminal plate, culmen cerebelli and cerebellar peduncle. Three patients had transient worsening of their deficits immediately after surgery. Three patients developed haemorrhages postoperatively requiring surgical evacuation. One of them died. None of the patients developed specific complications which could without any doubt be attributed to the approach. We concluded that in combination with intra-operative CSF drainage and the sitting position the infratentorial supracerebellar approach allows safe access to lesions situated in an area limited by the posterior part of the third ventricle, the fastigium level and both cerebellar peduncles.
Acta Neurochirurgica 02/1992; 114(3-4):135-8. · 1.52 Impact Factor
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ABSTRACT: The authors review their experience with a dorsolateral approach to the anterior rim of the foramen magnum and adjacent region. The operative technique includes exposure of the vertebral artery at C1, partial resection of the occipital condyle and lateral atlantal mass, and extradural drilling of the jugular tubercle. This approach has been applied in six patients who harbored intradural space-occupying lesions located ventral to the lower brain stem. Excision of the neoplasm was virtually total in all but one patient, in whom biopsy was the primary goal of the intervention. No morbidity and no mortality were associated with this approach. The main advantage of the dorsolateral, suboccipital, transcondylar route is the direct view it offers to the anterior rim of the foramen magnum without requiring brain stem retraction.
Neurosurgery 01/1992; 29(6):815-21. · 2.79 Impact Factor
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ABSTRACT: The authors review 26 patients with deep-seated cavernous angiomas which were removed by microsurgery. Ten of the angiomas were located in the insula and basal ganglia, 2 in the thalamus, 5 in the midbrain, 8 in the pons, and 1 in the brachium pontis. The patients were among 73 consecutive cases operated on between August 1983 and December 1989 for symptomatic cavernous angiomas in various locations. In 11 cases total excision of the cavernoma was achieved without producing additional neurological deficits. Postoperative neurological recovery was delayed in 7 patients. In the remaining 8, the complicated postoperative course was caused by bleeding from residual parts of the malformation or damage to long-tract pathways in two cases, respectively, vascular injury during dissection in three cases, and paradoxical air embolism in one case. In order to achieve a satisfactory surgical result, it is stressed that particular attention has to be paid to the operative approach, to careful dissection and complete removal of the malformation, to perforating arteries, and to anomalous venous drainage.
Acta Neurochirurgica 02/1991; 108(3-4):91-9. · 1.52 Impact Factor
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ABSTRACT: Some refinements of the surgical procedure are described in 12 patients (five females, seven males) operated on for neurovascular decompression (ND) in the presence of trigeminal neuralgia and hemifacial spasm. The patients were operated upon in the supine position, in which the use of a lumbar drainage facilitates the dissection from the beginning. The lateral suboccipital approach was performed by means of a semi-osteoplastic craniotomy with the use of bone chips to close the bone defects so that a good cosmetic effect could be achieved.
Acta Neurochirurgica 02/1991; 111(1-2):64-7. · 1.52 Impact Factor
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ABSTRACT: A series of 256 consecutive patients suffering from spinal tumours was studied with respect to the value of bilateral or unilateral surgical approaches. The case material included 152 extradural, 87 intradural, extramedullary and 17 intramedullary tumours. The cervical spinal cord was involved in 43, the thoracic in 152 and the lumbosacral region in 61 cases. Hemilaminectomy was chosen mainly for juxtamedullary tumours, while laminectomy was used for intramedullary tumours. No remarkable difference regarding the choice of approaches was found in extradural tumours. More than 60% of cervical or lumbosacral tumours were managed using unilateral procedures. A higher rate of surgical radicality but fewer complications, shorter stay in hospital and better early results were achieved using hemilaminectomy especially in patients with juxtamedullary tumours. From the observations it may be concluded that the results do not depend on the type of surgical approach but are closely related to the histology and location of tumours. Under the prerequisite of exact pre-operative definition of tumour location, unilateral approaches are advantageous for all kinds of spinal tumours especially for juxtamedullary benign tumours.
Acta Neurochirurgica 02/1989; 100(3-4):127-33. · 1.52 Impact Factor
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ABSTRACT: In the early years of skull base surgery, total tumor removal was often deemed impossible due to involvement of the intrapetrous carotid artery. In contrast, previously considered unresectable lesions may be removed totally in selected cases, with reasonable expectation of successful treatment at the present time. Current techniques and operative exposures, when modified to accommodate the problem of intracranial extensions of tumor and when approached with neurosurgical collaboration, permit the removal of many of these difficult tumors. This retrospective study of 33 patients treated over the past 5 years offers a critical analysis of our treatment, and a categorization of abnormalities known to affect this anatomic region containing the vessel.
Archives of Oto-Rhino-Laryngology 02/1988; 245(2):69-73.
