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PubMed1991

Acoustic schwannoma and epidermoid cyst occurring as a single cerebellopontine angle mass.

The case of a 66-year-old man with a 3-year progressive hearing loss and a homogeneous left cerebellopontine angle mass on magnetic resonance imaging scan is described. At surgery, the major portion of the mass was a typical encapsulated, solid, acoustic schwannoma, but the most rostral portion was a distinct, flaky, cystic mass without a well-defined capsule, typical of an epidermoid cyst. The radiographic and operative findings of this unique coexistence of two different benign cerebellopontine angle masses are presented.

Aged↗
PubMed1991

Inflammatory lesion mimicking a metastatic ependymoma.

A 2.5-year-old child who had undergone nearly total resection of an infratentorial ependymoma demonstrated a new enhancing lesion on the undersurface of the right cerebellar hemisphere 7 weeks after the initiation of adjuvant chemotherapy. The residual primary tumor demonstrated continued regression during chemotherapy, and magnetic resonance imaging of the spine and cytopathological examination of the cerebrospinal fluid showed no evidence for other sites of metastatic tumor. Because of the unusual anatomic and temporal characteristics of this lesion and despite radiographic criteria highly suspicious for a metastatic lesion, a biopsy was performed, revealing histological evidence of an inflammatory process.

Cerebellar Diseases↗
PubMed1997

Paramedian supracerebellar approach to the upper brain stem and peduncular lesions.

OBJECTIVE: The infratentorial paramedian supracerebellar approach is useful for lesions involving the upper brain stem or the cerebellar pedunculi. We provide a precise description of this approach and its indications. METHODS: Four patients were operated on using this approach. The lesions included a squamous cell carcinoma, a glioblastoma multiforme, a hematoma, and a cavernoma. The lesions involved the quadrigeminal plate, the superior cerebellar peduncle, the middle cerebellar peduncle, and the quadrangular lobule of the cerebellum. RESULTS: Postoperatively, there was no apparent aggravation of neurological symptoms. The main advantage of the approach was that the operation can be performed with a wide horizontal view without sacrificing the deep veins. CONCLUSIONS: It is concluded that lesions in the superior and inferior colliculus, superior and middle cerebellar peduncles, and quadrangular lobules of the cerebellum can be safely operated on with this approach.

Adult↗
PubMed1998

Assessment and surgical management of posterior fossa epidermoid tumors: report of 28 cases.

OBJECTIVE: The management of a series of 28 patients operated on for posterior fossa epidermoids is reviewed, emphasizing the need for long-term follow-up. We discuss the rationale for a comprehensive classification system that may allow the comparison of results from homogeneous series. METHODS: We grouped the tumors to differentiate the surgical management according to various tumor sites and the degree of extension. Twenty patients harbored tumors located in the cerebellopontine angle, five patients harbored tumors in the fourth ventricle, and three patients harbored tumors in the posterior fossa basal. In 17 patients, extensions of tumors outside the posterior fossa included the following regions: the suprasellar/ chiasmatic (n = 5), the parasellar/temporobasal (n = 5), and the mesencephalic/pineal (n = 7). Tumor extension was also defined by the number of regions involved. Pre- and postoperative magnetic resonance imaging and computed tomographic findings collected in 17 and 28 patients, respectively, were carefully evaluated. RESULTS: Clinical features and surgical approaches varied according to location and growth pattern. Fifty-seven percent of the tumors were completely removed. A higher total removal rate was achieved in patients with tumors confined to the primary location. One patient (3%) died in the perioperative period. Approximately half of the patients presented with transient mild focal deficit impairments resulting from the manipulation of the nervous structure over a wide area. There was a higher rate of surgical complications with fourth ventricle and mesencephalic extended cerebellopontine angle tumors. The mean follow-up period was 8.6 years. Thirty percent of the patients with subtotal removal experienced symptomatic recurrences after 8.1 years, whereas all patients with total removal were still asymptomatic. The recurrence-free survival rate was 95% at 13 years for patients with total removal compared with 65% for patients with subtotal removal. Problems of identification of tumor regrowth are discussed. CONCLUSION: By assessing posterior fossa epidermoids, we determined that location and extension play a major role in the prognosis. Our data suggest that more aggressive surgery is called for at first operation, and that a second operation should be planned when regrowth becomes symptomatic and/or tends to extend outside its original site.

Adolescent↗
PubMed2005

Neurotologic management of intracranial epidermoid tumors.

OBJECTIVES: Epidermoid cysts are the most common intracranial embryonal tumor, although they account for only 1% of all intracranial tumors. Epidermoids often spread into several intracranial compartments. Thorough preoperative surgical planning is imperative for safe epidermoid removal. This paper discusses the neurotologic management of intracranial epidermoid cysts STUDY DESIGN: Retrospective chart review. METHODS: A database search revealed 10 patients with diagnosis of intracranial epidermoid cysts between January 1, 1971 and December 31, 2003 at our institution. RESULTS: Six males and four females with ages ranging from 18 to 54 years of age underwent surgery between September 1, 1971 and November 4, 2003. The average tumor size was 3.9 cm; six originated in the cerebellopontine angle and four in the petrous apex. Six patients had a translabyrinthine approach to the tumor, two with additional transcochlear exposure. Two patients had tumors removed by way of the middle fossa approach and one through the suboccipital approach. Multiple cranial nerves were involved by tumor in all patients, including nerves III through XI. The internal carotid artery was involved by tumor in four patients. Multiple cranial nerve deficits were seen preoperatively, and facial weakness was the most common new deficit postoperatively. Eight patients required intradural access for complete tumor removal. Seven had complete tumor removal. Headaches were the most common complication. One patient had seizures postoperatively, and another had a malignant epidermoid, which resulted in death. CONCLUSIONS: Intracranial epidermoid cysts require complex surgical planning. They involve multiple cranial nerves and vascular structures. Complete resection is frequently possible with minimal new cranial nerve deficits.

Adolescent↗
PubMed1980

A follow-up study of very low-birthweight infants receiving ventilatory support by face mask.

Recent evidence has suggested that face-mask ventilation of very low birthweight (VLBW) infants may have serious neurological consequences. The 30 surviving VLBW infants from the neonatal intensive care unit at Hammersmith Hospital who had received ventilatory support via face masks over a 25-month period have been reviewed and compared with a control group. Neuropathological findings in the VLBW infants who died during this time have also been reviewed in relation to their ventilatory management. The findings suggest that face-mask treament did not have a major deleterious effect on the surviving infants. The factors which may determine the neurological sequelae of this form of ventilatory support are discussed.

Brain Diseases↗
PubMed1985

Neurological manifestations in a phase 2 study of 13 patients treated with doxyfluridine.

Doxyfluridine is a new cytostatic drug of the fluoropyrimidine group, which may prove to have a high antitumor activity with less toxic side effects. Thirteen patients with advanced colorectal cancer were given doxyfluridine 2 g/m2 as a one-hour infusion for five days every three weeks and examined neurologically and neurophysiologically. One patient experienced an acute, reversible cerebellopathy after the second treatment course and developed a progressive generalized encephalopathy during the subsequent third and fourth cycle. The frequency of cerebellopathy may depend on the dosage and type of administration of the drug. Five patients developed a mild, mainly sensory polyneuropathy. High age, weight loss and decreasing general condition seem to be important factors in the development of polyneuropathy during doxyfluridine treatment, and this stresses the importance of optimal nutrition during the treatment period.

Adult↗
PubMed1993

Lead encephalopathy mimicking a cerebellar tumor.

Encephalopathy is a rare but severe complication of lead poisoning, mainly due to cerebral edema. Usually diffuse, symptoms and signs are sometimes focal, suggesting a false diagnosis of tumor, particularly cerebellar tumor. We report such a case diagnosed by MR imaging in which early treatment for edema avoided neurosurgical exploration. Only six cases have been published since Biemond and Van Creveld's first report in 1939. Several data--clinical and experimental--providing specific involvement of cerebellum in lead poisoning are emphasized.

Cerebellar Diseases↗
PubMed1988

Instability in human forearm movements studied with feed-back-controlled muscle vibration.

1. Frequency-modulated vibration was applied to the elbow flexor and extensor tendons to produce reflex movements of the forearm in normal subjects. The modulating (command) signal caused equal and opposite deviations from the 40 Hz carrier frequency so that when flexor vibratory frequency increased, extensor frequency decreased, and vice versa. 2. It is argued that the movements resulted largely from the reflex action of muscle spindle primary afferents whose firing frequency had been 'taken over' and modulated by the vibration. 3. Bode plots relating forearm movements to command signal (modulating) frequency showed the transfer function of the Ia afferent-CNS-muscle-load system to have a low-pass filter characteristic. The phase lag of movement on command increased progressively with command signal frequency, exceeding 180 deg at 3-4 Hz. 4. The transduced forearm movements were fed back to provide the command signal to the vibrators (and thus indirectly to the spindle afferents) via a filter mimicking the dynamic responsiveness of muscle spindle primary endings. Our aim was to 'break into' the reflex arc, and re-route it so that we could artificially vary the gain without significantly altering the dynamics of the pathway. 5. Nearly all subjects developed forearm oscillations (tremor) when the gain exceeded a threshold value. Subjects varied widely in their threshold, though for a given subject the threshold remained fairly constant from day to day. The results suggest that reflexly active individuals may not have a large safety margin with respect to forearm instability. 6. The frequency range of the oscillations observed in seven subjects was 3-8 Hz. The frequencies depended upon the level of flexor-extensor co-contraction, and increased from 3 to 5 Hz at 10% co-contraction to 5-8 Hz at 100% co-contraction. An analysis of the mechanical impedance of the arm provided estimates of tremor frequencies consistent with these results. 7. These unexpectedly low tremor frequencies led us to propose that it may be erroneous to expect stretch reflexes to contribute to forearm tremor in the range 8-12 Hz (e.g. physiological and 'enhanced' physiological tremors). Rather, their contributions should be sought in the range 3-8 Hz (e.g. pathological tremors such as those of Parkinson's and cerebellar disease).

Action Potentials↗
PubMed1980

Mechanism of rotatory eye movements in opsoclonus.

'Rotatory nystagmus', in which the visual axis of the eye moves involuntarily in the horizontal and vertical planes describing a closed loop trajectory, was analysed by means of combined video and electro-oculography in a patient with multiple sclerosis having numerous ocular signs of cerebellar disease. The rotations were sporadic, isolated single cycles having stereotyped, crescentiform loop shapes. Each consisted of a combination of a single cycle of vertical ocular flutter, the onset of which was followed 40 to 50 milliseconds later by a single cycle of horizontal ocular flutter. The timing relationship between flutters suggest that the vertical and horizontal systems had become somehow entrained. Rotatory nystagmus is saccadic in nature and arises from a unique timing relationship between vertical and horizontal flutter.

Adult↗
PubMed2004

Evidence for distinct cognitive deficits after focal cerebellar lesions.

OBJECTIVES: Anatomical evidence and lesion studies, as well as functional magnetic resonance imaging (fMRI) studies, indicate that the cerebellum contributes to higher cognitive functions. Cerebellar posterior lateral regions seem to be relevant for cognition, while vermal lesions seem to be associated with changes in affect. However, the results remain controversial. Deficits of patients are sometimes still attributed to motor impairment. METHODS: We present data from a detailed neuropsychological examination of 21 patients with cerebellar lesions due to tumour or haematoma, and 21 controls matched for age, sex, and years of education. RESULTS: Patients showed deficits in executive function, and in attentional processes such as working memory and divided attention. Further analysis revealed that patients with right-sided lesions were in general more impaired than those with left-sided lesions. CONCLUSIONS: Those hypotheses that suggest that lesions of the right cerebellar hemisphere lead to verbal deficits, while those of the left lead to non-verbal deficits, have in part been confirmed. The generally greater impairment of those patients with a right-sided lesion has been interpreted as resulting from the connection of the right cerebellum to the left cerebral hemisphere, which is dominant for language functions and crucial for right hand movements. Motor impairment was correlated with less than half of the cognitive measures, with no stronger tendency for correlation with cognitive tests that require motor responses discernible. The results are discussed on the basis of an assumption that the cerebellum has a predicting and preparing function, indicating that cerebellar lesions lead to a "dysmetria of thought."

Adult↗
PubMed1982

Acquired pendular nystagmus: its characteristics, localising value and pathophysiology.

Investigations were made of 16 patients with acquired pendular nystagmus and a further 32 cases reported in the literature were reviewed. Amongst our own patients two thirds had multiple sclerosis, almost one third a cerebrovascular accident or angioma and two had optic atrophy with squint. The nystagmus took forms which could be monocular or binocular, conjugate or disconjugate and could involve movements about single or multiple axes. Spectral analysis was used to characterise the amplitude and frequency of the movements and to estimate the degree of relationship (coherence) between movements of the two eyes or between movements of one eye about several axes. The oscillations ranged in frequency from 2·5 Hz to 6 Hz, with typical amplitudes between 3° and 5°. In a given patient all oscillations, regardless of plane, were highly synchronised. Somatic tremors of the upper limb, face and palate associated with the nystagmus were often at similar frequencies to the eye movement. The other ocular signs common to all our patients were the presence of squint with failure of convergence. Most patients also had skew deviation or internuclear ophthalmoplegia or both. The major oculomotor systems, that is, saccades, pursuit, optokinetic and vestibulo-ocular reflexes could be intact. It is inferred that the mechanism responsible for the pendular nystagmus lies at a level which is close to the oculomotor nuclei so that it can have monocular effects but is not part of the primary motor pathways. It is possible that this mechanism normally subserves maintenance of conjugate movement and posture of the eyes. The periodicity of the nystagmus is likely to arise from instability in a certain type(s) of neurone, for the associated somatic tremors have similar characteristics and yet involve very different neuronal muscular circuitry. Prognosis for cessation of the nystagmus is poor. In five patients with multiple sclerosis it was suppressed by intravenous hyoscine with, however, unacceptable subsequent side effects.

Adult↗
PubMed1988

Stability and tremor in the fingers associated with cerebellar hemisphere and cerebellar tract lesions in man.

Stability and tremor in the fingers were assessed by a new technique in patients with unilateral cerebellar syndromes. In 11 patients with unilateral cerebellar hemisphere lesions tremor was observed with either clear tremor at 5-7 Hz or prolongation of the tremor profile out to 11 Hz. In 10 patients with unilateral cerebellar lesions associated with ipsilateral past-pointing there was an asymmetry in finger stability. Compared with normal subjects there was a significant decrease in stability contralateral to the lesion, while the ipsilateral side's stability was not different from normal. In patients with high brain stem lesions at the level of cranial nerves VII and above, tremor had frequencies of 5-7 Hz. In those with lower brain stem lesions, often with long tract signs as well, the frequencies of tremor were faster, 8-11 Hz, which may reflect damage to cerebellar inflow tracts. A broad if not specific correlation was found between clinical condition, site of lesion and finger stability and tremor.

Adolescent↗
PubMed1988

Central motor conduction in degenerative ataxic disorders: a magnetic stimulation study.

Central motor conduction to small hand muscles was measured using magnetic stimulation of the motor cortex and electrical stimulation of proximal motor roots in 11 patients with Friedreich's ataxia, 10 patients with early onset cerebellar ataxia with retained tendon reflexes (EOCA) and 13 patients with late onset degenerative cerebellar disease (LOCD). Central motor conduction was abnormal in 91% with Friedreich's ataxia, 70% with EOCA and 38% with LOCD. Central motor conduction abnormalities were not specific to individual disorders but were more severe and were related to disease duration in Friedreich's ataxia and EOCA.

Adult↗
PubMed1988

Visual and mechanical control of postural and kinetic tremor in cerebellar system disorders.

The influence of alterations in visual guidance and somaesthetic sensory inputs was studied in five patients with kinetic and postural tremor characteristic of cerebellar impairment. The patients performed wrist flexion-extension movements or movements about the shoulder with or without visual guidance. Different types of mechanical loads were applied to oppose the wrist movements. The tremor was greatest when the patients used visual cues to guide movements. Kinetic tremor was substantially suppressed during performance of similar movements that were not guided directly by vision. Viscous loads suppressed the tremor nearly linearly, whereas constant loads opposing extension enhanced the tremor. The postural tremor was not observed during isometric contractions. These results support the view that processing of visual information contributes to the impairment of movement in disorders with cerebellar-type tremor and that certain somaesthetic inputs can selectively influence the generation of postural tremor.

Adult↗