Translabyrinthine removal of large acoustic tumors

The translabyrinthine technique was used to remove tumors of various sizes in 50 cases. Outcome is presented stressing immediate and eventual facial function, for tumors measuring 20, 25, 30, 35, and 40 mm. Immediate facial function is a good predictor of permanent facial activity; regeneration of the facial nerve gives good but never perfect function. Except for preservation of hearing, translabyrinthine surgery gives equally good and probably better results than other techniques.

Cavitron ultrasonic surgical aspirator and visual evoked potential monitoring for chiasmal gliomas in children. Report of two cases

The Cavitron ultrasonic surgical aspirator (CUSA) and intraoperative visual evoked potentials (VEP's) were found to be helpful in treating two children with difficult chiasmal gliomas. Approximately 60% of one tumor and 85% of the other was resected without change in the intraoperative VEP's and with no change in postoperative visual fields or acuity. The CUSA-VEP technique is useful in the infant to "buy time" for brain maturation, delaying or obviating subsequent radiotherapy. This approach may be helpful in the older child to reduce the tumor burden for subsequent chemotherapy. Chiasmal gliomas can be subtotally resected with the CUSA while visual function is monitored by intraoperative VEP's.

[Endocrine function of the pancreas in tumors of the chiasmal-sellar region]

A clinicobiochemical study of 10 patients with tumors of the chiasmal sellar region and 8 healthy persons using the i. v. glucose tolerance test (IGTT) made it possible to reveal disorder of pancreatic alpha- and beta-cell function in the patients with tumors. A distinct picture of the chiasmal sellar process with the involved hypothalamus was clinically determined in all the patients. Radioimmunoassay of immunoreactive insulin, glucagon, C-peptide and glucose revealed fasting hyperinsulinemia in the presence of both hypo- and hyperglycemia. The latter was accompanied by a raised level of glucagon in the blood. The IGTT revealed in the patients with tumors of the chiasmal sellar region hyperreactivity of beta-cells and a decrease in the sensitivity of alpha-cells to glucose as well as glucose tolerance that may be both regarded as pathogenetic factors of the development of a prediabetic condition in such patients.

Use of antidromic recording to monitor facial nerve function intraoperatively

This report describes a technique for monitoring facial nerve activity intraoperatively utilizing antidromic nerve stimulation and sequential averaging of the evoked responses. Compound facial nerve action potentials are obtained reliably even in the presence of paralyzing doses of muscle relaxants, which render the conventional methods useless. The electrophysiological setup is straightforward, and we utilize the same sequential averaging equipment with which we monitor cortical evoked responses intraoperatively. This technique facilitates identification of the facial nerve in large cerebellopontine angle tumors with minimal mechanical trauma. Recordings from eight clinical cases are presented to illustrate the reliability and reproducibility of this technique.

Vegetative dysfunctions of the hypothalamus

Experiment and clinical evidence of hypothalamic influence on autonomic function has accumulated since the early part of this century. Localization of hypothalamic lesions is difficult, and damage must be bilateral to produce symptoms. Caloric balance may be altered, with ventromedial lesions causing hyperphagia, and lateral hypothalamic lesions producing a syndrome of aphagia and weight loss in experimental animals. Gastric ulcerations are associated with brainstem lesions, including the diencephalon. Anterior hypothalamic lesions cause hyperthermia, while posterior lesions result in hypothermia, often accompanied by disturbance of sweating mechanisms. Disorders of sleep and wakefulness are seen clinically in encephalitis lethargica and Wernicke's syndrome, both associated with hypothalamic damage. The hypothalamus is the regulator and co-ordinator of central autonomic activity.

Patterns of phoneme identification error in cochlear and eighth-nerve disorders

The purpose of this study was to determine whether patterns of phoneme identification error differ among listeners with cochlear and retrocochlear auditory disorder. Speech intelligibility performance was analyzed in 15 patients with confirmed eighth-nerve disorder and in 15 patients with cochlear disorders, matched to the retrocochlear group for age and audiometric configuration, using confusion matrices derived from responses to a monosyllabic word list. Results indicated that: (1) vowel errors were more prevalent in the retrocochlear group and varied directly with increasing stimulus presentation level; and (2) consonant errors did not differ in type or relative frequency between the two groups, nor was there a level-dependent effect for consonant errors. These results are supported by the results of closed-set vowel identification tests and thus do not appear to be an artifact of open-set testing. Vowel errors may account for a major part of the speech 'rollover' phenomenon typical of retrocochlear auditory dysfunction.

Optic nerve sheath meningiomas. Clinical manifestations

A retrospective clinical study of optic nerve sheath meningiomas based on 22 patients showed that symptoms most commonly develop in women between the ages of 35 and 60 years. The most common presenting symptoms were decreased vision and transient visual obscurations. In the earliest stages, many patients presented with normal to mildly impaired acuity (despite subjectively decreased vision), optic disc edema and enlargement of the blind spot. Optic disc edema was frequently associated with refractile bodies indicative of chronic swelling. Optic disc edema preceded the development of optic atrophy. Another group of patients presented with a history of longstanding vision loss, visual acuity of 20/200 or worse and optic atrophy. Optociliary shunt vessels were late findings only seen in five patients. The most consistent visual field abnormality was peripheral constriction. Cecocentral scotomas were uncommon. Intracranial involvement was present in five patients. There were two patients with bilateral optic nerve sheath meningiomas without CT evidence of intracranial involvement. Computerized tomography was found to be indispensable in the diagnosis of optic nerve sheath meningiomas and the detection of intracranial involvement.

Monocular nystagmus in infancy and early childhood

Of 11 young children (six girls and five boys, ranging in age from 4 to 14 months) with monocular nystagmus, six were found to have chiasmal tumors whereas only four had spasmus nutans. Differentiating features between these two groups included decreased vision and optic nerve anomalies (including four cases of optic nerve hypoplasia) in the tumor group. However, we found that no consistent clinical finding absolutely separates these groups. We therefore recommend that all infants and children with monocular nystagmus or the other features of spasmus nutans should undergo computed tomographic scanning.

Trigeminal neurinoma with unusual presentation. Report of a case with trigeminal somatosensory-evoked response

A patient with trigeminal neurinoma, presenting unusual symptoms, is described. There was no trigeminal sensory or motor deficit. The only presenting symptoms were unilateral abducens nerve paresis and alternating hemiplegic episodes. The trigeminal somatosensory-evoked response was normal before surgery. After complete removal of the tumor from both the posterior and middle cranial fossae, severe trigeminal sensory deficit ensued, accompanied by impairment of the evoked response. Improvement of the trigeminal nerve function could be predicted by significant changes in a repeat trigeminal sensory-evoked response obtained 2 months after the operation.

Lateralization, impedance, auditory brain stem response and synthetic sentence audiometry in brain stem disorders

Applied individually, the conventional audiometric tests are unsatisfactory in the diagnosis of retrocochlear disorders. An accurate identification of a retrocochlear lesion, however, is not always possible using a single test, and only an appropriate test battery provides the basis for correct prediction of a retrocochlear lesion. Because of this observation, lateralization tests, impedance studies, auditory brain stem responses and speech audiometry with synthetic sentences have been applied to patients affected with retrocochlear disorders (acute nucleoreticular vestibular syndrome, multiple sclerosis and focal lesions). Analysis of the results has demonstrated the value of the tests employed, but the various tests were not strongly correlated and are therefore complementary.

Differential facial nerve function in tumors of the internal auditory meatus

Fifty-five consecutive cases of neoplastic involvement of the internal auditory meatus resulting in ipsilateral retrocochlear auditory dysfunction were reviewed. The majority of these tumors (89%) were solitary schwannomas of the eighth nerve. Eleven percent were other tumors. Preoperative facial paralysis was unusual in eighth nerve schwannomas (6.1%) and much more common in other tumors (66.6%). These data tend to suggest that facial paralysis preoperatively increases the probability that the tumor is other than an eighth nerve schwannoma. Furthermore, facial paralysis resulting from an eighth nerve schwannoma indicates a poorer prognosis for ultimate facial nerve function. The small numbers in this series, though far from conclusive, suggest that normally functioning facial nerves may be infiltrated by eighth nerve schwannomas. Failure of eventual recovery of facial nerve function in the postoperative period may suggest tumor infiltration.

Ulnar F-wave conduction velocity in epidural metastatic root lesions

In 40 controls and 19 patients with neoplastic lesions of the eighth cervical and first thoracic nerve roots confirmed by myelography, ulnar F-wave conduction velocity (FWCV) was estimated using the shortest F-wave latency (FWL). F-waves were recorded from needle electrodes inserted in the abductor digiti minimi manus muscle after stimulation of the ulnar nerve at the wrist. Motor nerve conduction velocities of distal ulnar segments were normal. It was found that the ulnar FWCV decreases significantly with increasing age. This is not true for FWL. During the initial examinations ulnar FWCV was delayed in 18 patients. At follow-up, ulnar signs correlated well with changes in FWCV. Low F-wave frequency and wide FWL differences are also important features in ulnar root disease.

Bilateral acoustic neuromas: clinical aspects, pathogenesis, and treatment

Fifteen patients with bilateral acoustic neuromas are presented. Ten patients became symptomatic before age 21, and 9 of these patients developed additional central nervous system tumors. Cutaneous manifestations of neurofibromatosis and a positive family history of this disorder were absent in many of the patients. Most patients required multiple surgical procedures, and the timing, techniques, and results of these operations are reported. The pathogenesis of these tumors, the genetic aspects of this disorder, and potential treatment alternatives are discussed.

A study of glucocorticoid receptors in intracranial tumors

Tissue samples from 20 patients with various intracranial tumors and one case of cerebral contusion were analyzed for the cytosolic glucocorticoid-receptor concentration using isoelectric focusing in slabs of polyacrylamide gel. It is pointed out that the clinical response to dexamethasone in brain edema associated with various intracranial lesions is, to some extent, parallel to the glucocorticoid-receptor concentration in these tumors. The findings in this investigation suggest that the cytosolic glucocorticoid receptor might be responsible for the initiation of a series of biochemical effects of steroids affecting brain edema. It is possible that the first step in eliciting a beneficial clinical response to dexamethasone in patients with brain tumors is the formation of a steroid-receptor complex in the peripheral parts of the tumor.

Visual evoked potentials in chiasmal gliomas in four adults

Visual evoked potentials (VEPs) were recorded from four patients with surgically verified chiasmal gliomas. Despite good visual acuity, 6/12(20/40) or better in each eye, these patients showed substantially reduced VEP amplitudes to a diffuse flash stimulus and hardly detectable responses to a highly textured checkerboard-pattern stimulus. The dissociation between evoked electrical activity and visual acuity is noteworthy; this differs from previously reported findings in patients with extrinsic compressing lesions of the chiasm or with lesions of demyelinating disease, which usually reduce VEP amplitude and increase conduction time in rough proportion to a loss of visual acuity.

[Blink reflex and jaw reflex in neurinoma of the acoustic and trigeminal nerves (author's transl)]

The blink reflex was studied in four patients with neurinoma of the acoustic nerve and in two patients with trigeminal neurinoma. It was abnormal in all cases except in one neurinoma of the acoustic nerve inside the canal. The jaw reflex, studied in four cases, showed unilateral impairment in two cases of trigeminal neurinoma and one case of acoustic neurinoma; it was normal in the case of acoustic neurinoma in the canal. The blink reflex and jaw reflex merit inclusion among the further tests conducted in cases of suspected neurinoma of the trigeminal or acoustic nerves. However, they are of less interest than oto-vestibular tets in the early diagnosis of neurinoma of the eighth nerve. These techniques deserve a place of choice in investigations of atypical facial neuralgia in general and suspected neurinoma of the trigeminal in particular.

Study of a simultaneous lobe-vertex and membrane-vertex recording technique in auditory brainstem response

The study of a simultaneous lobe-vertex and membrane-vertex recording in auditory brainstem response was performed in normal adults and in patients suffering from brainstem disorders. It was demonstrated that in normal subjects the detectability of waves I and V depends on the site of the recording electrodes and there is no statistical difference between the two recording methods in the latencies of the two waves. We reported 3 typical cases that illustrate the value of this recording method in the detection of the cochlear nerve or the brainstem disorders.