[Significance of comparing the results of caloric and vestibulometric rotation tests]

The use of modified, less laborious, easier endured vestibulometric tests made it possible to facilitate diagnosing Menière's disease and neurinomas of the vestibular nerve. Comparison of nystagmometric findings recorded in the same patient during caloric and rotation tests using the diagnostic model of a bithermal test permitted some assumptions to be made in relation to the mechanisms for nystagmogenesis associated with pathologic states in ear labyrinth and vestibular portion craniocerebral (VIII) nerve. It is found that in the majority of Meniere's disease cases (61%) there is a decrease in an intensity of caloric nystagmus induced by Lasix dehydration effect. This phenomenon can be explained by a reduced difference in energy levels of two complexes of vestibular nuclei and, therefore, by an attenuated afferents to peripheral compartment of vestibular system. In neurinoma of aural nerve, the phenomenon of vestibular recruitment (20%) was noted. The diagnostic model of a bithermal test makes it possible to explain an effect of smoothing out the nystagmic responses induced by an intensive stimulus when used a sinusoidal stepwise test. The observed vestibular recruitment results from the severe disorder of one of the afferent inputs due to destruction of induced by tumor pressure.

Herald facial numbness

Three unusual patients who developed subacute facial numbness as the heralding symptom of an expanding tumor that involved the trigeminal nerve fibers are reported. The first patient had clinical and electrophysiological evidence of an isolated mental neuropathy as a result of metastatic lesions with bone destruction from a renal cell carcinoma. The second patient had a sensorimotor trigeminal neuropathy caused by a direct compression of the semilunar ganglion by a cavernous hemangioma of Meckel's cave. The last patient experienced facial numbness as the unusual presenting manifestation of a primary brainstem lymphoma. Patients 1 and 3 died a few weeks after the admission, whereas patient 2 poorly recovered. Despite the availability of new techniques for early diagnosis, this report demonstrates how difficult it can initially be to differentiate a 'benign' trigeminal neuropathy from serious conditions and underscores the poor prognosis of fifth nerve fibers involvement by an expanding mass. Early referral with clinical and electrophysiological evaluation appears to be of crucial importance.

Painful intraorbital meningiomas

Three cases are reported of meningioma involving the orbital apex presenting with either progressive or episodic retroocular pain. In two cases pain was steroid responsive and in one of these patients this led to an initial diagnosis of orbital pseudotumour. Pain preceded visual loss and other symptoms by many months and these cases illustrate the importance of full investigation and where necessary surgical exploration in cases of apparent orbital inflammatory disease with an atypical or progressive course.

Recurrent acoustic tumor after a suboccipital removal

Surgery for acoustic tumors has several priorities. First and foremost is the preservation of life with the total removal of the tumor; second is the preservation of the facial nerve; and last, when applicable, is the preservation of hearing. During the suboccipital (retrosigmoid) removal of a tumor, the surgeon unknowingly may leave tumor remnants leading to regrowth. We present five cases of recurrent acoustic tumors after a suboccipital removal. Inadequate drilling exposure of the internal auditory canal was the probable direct cause for tumor recurrence. A translabyrinthine removal is the best approach for total exposure of the entire internal auditory canal. The consequences of small tumor remnants will be discussed as well as their clinical relevance. Current radiological imaging and surgical techniques that avoid residual tumor will be presented.

[Octopus perimetry in neuro-ophthalmologic diseases. A contribution to the problem of optimal program choice based on 427 cases]

From the patient population of the University Eye Clinic Basel 427 cases, who had been tested with the Octopus perimeter 201 because of neuro-ophthalmologic problems, were retrospectively examined. Above all it was interesting to find out, which program to use in order to get a maximum degree of information with a minimum of examinations. The quantitative programs 31 to 34 gave most often the clinically relevant information concerning the opticus- and chiasma affections. The only exception was the anterior ischemic opticoneuropathy where the semiquantitative program 07 delivered the better information. With supragenicular affections program 07 delivered by far, and most often, the clinically relevant information. Because of our results we can make the following recommendations: if a pregenicular lesion is suspected, it is sensible to use quantitative programs with a homogenous test point distribution within 30 degrees testing area. If a supragenicular lesion is suspected, the registration of the total extension of the defect is of greater practical value than a quantitative threshold determination. In this case, the survey program 07 is suitable. If visual disturbance is present, without a hint of its location, it is recommended to start with the survey program 07 and thereafter, according to test results, specifically continue with a quantitative program.

Brain-stem auditory evoked responses in 56 patients with acoustic neurinoma

The brain-stem auditory evoked responses (BAER's) recorded from 56 patients with acoustic neurinomas were analyzed. Ten of the patients had intracanalicular tumors and 46 had extracanalicular tumors. It was possible to obtain BAER's following stimulation of the affected side in 28 patients and after stimulation of the unaffected side in all 56. Five patients (11%) had normal BAER's following stimulation of both sides; three of these patients had intracanalicular tumors. Among BAER's obtained following stimulation of the affected ear, the mean interpeak latency (IPL) for peaks I to III associated with extracanalicular tumors was significantly prolonged relative to controls (p less than 0.001), and linear regression analysis revealed a significant positive correlation between tumor size and IPL of peaks I to III (p less than 0.05). Analysis of the 56 BAER's recorded after stimulation of the unaffected side revealed a significant positive correlation between the IPL's of peaks III to V and tumor size (p less than 0.001). This correlation was not strengthened when accounting for the degree of brain-stem compression. Finally, evidence of preserved function within the auditory pathway, even in the presence of partial hearing loss, is presented. This finding suggests that more patients might benefit from surgical procedures that spare the eighth cranial nerve.

[The effect of visual deafferentation on changes in the cerebral blood flow during photic stimulation]

With the aid of transcranial dopplerography, linear velocity of the blood flow was recorded in major cerebral vessels in resting and in photostimulation in 18 healthy subjects and 7 patients with unilateral lesion of visual pathway and exclusion of one half of the field of vision. The photostimulation accelerated the blood flow in middle cerebral arteries by 4.3% and in posterior cerebral arteries by 26.3% in healthy subjects. No acceleration of the blood flow occurred in posterior cerebral artery on the side of unilateral lesion of visual pathways.

[A case of intracranial hypoglossal neurinoma with no preoperative hypoglossal nerve palsy]

A case of intracranial hypoglossal neurinoma without hypoglossal nerve palsy is reported. A 43-year-old housewife was admitted to our hospital with vertigo and left occipital headache. Neurologically, no cranial nerve deficits were present. CT scan and cerebral angiography showed a mass in the lower left posterior fossa. MRI also revealed a well circumscribed extra-axial mass compressing brain stem and cerebellum to the right. Left suboccipital craniotomy was performed and the tumor was removed subtotally. From the operative findings, the 8th to 11th cranial nerves were not related to the tumor, however, the origin of the tumor was not confirmed. The histology showed Antoni A type neurinoma mixed partially with Antoni B type. After the operation, the tongue deviation appeared to the left, but no other cranial nerve deficit was noticed. Post-operative neuroradiological reexaminations defined slight enlargement of the hypoglossal canal. Then, we concluded that the origin of the tumor must have been the hypoglossal nerve. Most intracranial hypoglossal neurinoma grow in the hypoglossal canal followed by enlargement or erosion of the hypoglossal canal. The author thought that this case suggests that this hypoglossal neurinoma originated from a few rootlets of hypoglossal nerve and grew mainly between the medulla and the hypoglossal canal.

[Tractotomy and partial nucleotomy as a form of therapy in refractory pain of the trigeminal nerve and cancer pain in the head and neck area]

Persistent trigeminal neuralgia, herpes zoster neuralgia of the first division of the trigeminal nerve and pain caused by cancer situated in the head and neck pose frustrating problems for patients and physicians. Tractotomy and/or partial vertical nucleotomy of the subnucleus caudalis nervi trigemini offers a logical approach to the treatment of such pain, since these structures contain fibres of the Vth nerve, as well as the somatosensory fibres of the VIIth, IXth and Xth nerve. Tactile and some thermal sensitivity of the face is preserved and anaesthesia dolorosa and keratitis neuroparalytica is avoided. Over the past 30 years 370 patients with therapy-refractory trigeminal pain, pain due to cancer of the head and neck and herpes zoster trigeminal pain were treated by means of tractotomy (personal series of V. Grunert), including 30 patients who underwent partial vertical nucleotomy. The mean age of the patients was 68 years (range 54-84 years). The mortality in this series was 0.9% (4 patients; one operative mortality due to air embolism, one postoperative cardiac failure following myocardial infarction and two intracerebral haematomas). 60% of the patients with persistent trigeminal neuralgia were pain-free and 28% improved, whereas 12% were unchanged or suffered from recurrent pain. Of the patients with cancer who complained of pain derived from the Vth, VIIth, IXth and Xth nerve, 40% demonstrated marked pain relief and 60% showed no improvement. Tractotomy and partial vertical nucleotomy offer a valuable method in experienced hands for relieving pain where other methods have failed.

Preoperative and postoperative auditory brain-stem response results for patients with eighth-nerve tumors

Preoperative and postoperative auditory brain-stem response results and audiologic data were reviewed for seven patients whose hearing was preserved after eighth-nerve tumor surgery. Auditory brain-stem response absolute latencies (I, III, and V) and interpeak intervals (I-III, III-V, and I-V) were identified more often postoperatively than preoperatively. Even though postoperative absolute latencies were usually abnormal, the interpeak intervals were usually normal following surgery. Postoperative hearing sensitivity was unchanged or slightly poorer for five of the seven patients, but postoperative speech discrimination was the same or better for six of the seven patients. All three patients having acoustic reflex testing showed improvement postoperatively.

Retinal origin of VECP delays as revealed by simultaneously recorded ERG to patterned stimuli

Electroretinal and electrocortical potentials evoked by reversing checkerboards (PERG, PVECP) were simultaneously recorded in diseases of the central retina (10 patients) and in tumor-related optic nerve disorders (11 patients) exhibiting comparable P-100 delays in the PVECP. Retinal diseases showed a peak-time delay both in the PERG and in the PVECP, while optic nerve disorders revealed no delay in the PERG. Thus, simultaneous recording of PERG and PVECP may differentiate retinal from postretinal disorders of the visual system. The method also may provide information about the site of an underlying disorder in cases of visual disturbance without obvious changes of the ocular fundus.

[Monitoring control of the visual evoked potentials during the surgical treatment of tumors of the chiasmal-sellar area]

Visual evoked potentials were recorded in different stages of the operation in 12 patients with tumors of the chiasmal-sellar region. A correlation was noted between the dynamics of the P100 latent period and the changes of visual functions after the operation. Intraoperative monitoring of visual evoked potentials makes it possible to appraise the functional condition of the optic nerves objectively and correct the techniques and tactics of the operative intervention.

Our treatment philosophy of gliomas of the anterior visual pathways

Therapeutic strategy and clinical course of 28 low grade gliomas of the anterior visual tract were analyzed and compared with results of quantitative microscopic examination. Children operated on between 1978 and 1987 were divided into four groups according to the tumor site. DNA microfluorometry and image analysis of bioptic material were used for an objective differentiation between morphologically almost identical gliomas classified as pilocytic astrocytomas (grade I). Six cases of posttraumatic gliosis were examined as controls. Results were tested with factor analysis and by multiple comparison procedures. Significant differences between quantitative parameters of tumors located along the visual pathway were found with the use of computer-aided microscopy. These results corresponded with the clinical experience and patient's outcome. A radical surgical intervention (without additional oncologic therapy) was recommended for patients with intraorbital gliomas which revealed favorable quantitative microscopic features.

Schwannoma of the oculomotor nerve

A case is described of oculomotor nerve sheath tumour presenting with signs and symptoms of a posterior fossa space occupying lesion with minimal involvement of the IIIrd nerve.

Vagal nerve schwannoma--a new diagnostic sign

A case of vagal nerve schwannoma with a new physical sign is presented. The tumour was largely cystic and aspiration, performed twice, immediately elicited a cough reflex from the patient. Treatment was by total excision and the patient made a good recovery. Complete cystic degeneration of a vagal nerve schwannoma is uncommon. A search of the literature has failed to find any previous reports of fine needle aspiration causing a cough reflex in these tumours.

Acoustic tumor surgery. Prognostic factors in hearing conversation

Preoperative selection criteria for hearing conservation surgery in patients with acoustic tumors continues to be unresolved. The level of hearing that is worth saving is still debatable. However, most acoustic tumor surgeons agree that hearing preservation is less likely the larger the tumor. We reviewed the results of 106 middle fossa acoustic tumor removals with attempted hearing preservation. Measurable postoperative hearing remained in 59% of 97 cases analyzed for postoperative hearing results. Tumor size, preoperative auditory brain-stem response, and preoperative electronystagmography were found to be useful in predicting successful postoperative hearing preservation. We found no correlation between the level of preoperative hearing and our ability to preserve measurable postoperative hearing. A new classification system is proposed for reporting hearing results after acoustic tumor surgery. It is based on functional hearing results and we believe it is simpler than previously proposed systems.

Visual evoked potential abnormalities in chiasmal lesions

Pattern reversal visual evoked potentials (VEPs) were recorded from 38 patients with lesions affecting the chiasmal area. Lesions were confirmed by computer tomography and all patients had ophthalmologic examination. VEPs to full-field stimulation (0-16 degrees r) were compared with those obtained with half-field stimulation. Changes in VEPs were seen as a nonrecordable or attenuated P 100 (abnormal amplitude ratio) or as a prolonged P 100. Analysis of the records showed that temporal half-field stimulation (crossed fibers) yielded a higher rate of abnormal responses (80%) than full-field stimulation (66%). The most frequent abnormality in the former stimulation was a nonrecordable P 100 (42%) and in the latter an abnormal amplitude ratio of P 100 (41%). When the uncrossed fibers were stimulated with the nasal half-field, abnormalities were detected in 32% of responses. Lesions in the region of the sella turcica were also associated with a high incidence of delayed responses (39% of patients when crossed fibers were stimulated). However, the magnitude of the delays was smaller (1-32 ms) compared with delays in patients with demyelinating disease. Findings of this study show that half-field stimulation assists in the interpretation of responses to full-field stimulation. In addition, half-field stimulation can reveal abnormalities that are not detected with full-field stimulation.

Wave V interaural latency differences as a function of asymmetry in 2,000-4,000 Hz hearing sensitivity

Interaural latency differences for wave V (IT5) were measured for 406 patients having cochlear hearing loss and for 36 patients with VIIIth nerve tumors. The incidence of IT5 values exceeding 0.2, 0.3, and 0.4 msec was plotted as a function of the degree of asymmetry in hearing sensitivity for 2,000-4,000 Hz. In general, the patients with cochlear hearing loss and the greatest degree of hearing asymmetry yielded IT5 values that exceeded 0.2, 0.3, or 0.4 msec more frequently than patients with more symmetric hearing losses, and this trend was apparent for all degrees of hearing loss. For the VIIIth nerve tumor patients, IT5 data were scattered widely regardless of symmetry or asymmetry of hearing sensitivity. The false-negative rate was 8% when IT5 was greater than 0.4 msec.

Pathophysiology of facial nerve disorders

This issue of The American Journal of Otology includes the last of a series of articles on facial nerve disorders, which collectively are known as the "Facial Nerve Manual." In the early 1980s, Dr. Mark May chaired the AAO-HNS Facial Nerve Committee. One of the tasks he initiated was the creation of a Facial Nerve Manual, assigned to a small group of clinicians at the COSM Meeting in the spring of 1984. The purpose of this work was to disseminate practical information on the management of selected facial nerve problems, one of the primary charges of the Committee. Work began slowly, but surely. During Dr. Gale Gardner's tenure as Committee chairman, manuscripts were reviewed and edited by Dr. Nels Olson, and The American Journal of Otology agreed to publish the manual. Perhaps more than anyone else, Dr. Olson worked tirelessly to create a finished product of consistent style and content. Ever since the original writing and editing, controversial topics continue to emerge. As each chapter is published individually over this year, concepts may change, and the reader is encouraged to explore these issues in more depth. Drs. May, Gardner, Olson, and all the individual authors are to be congratulated for their efforts. The Committee sincerely thanks The American Journal of Otology for supporting this work.

[The results of direct electrostimulation of the involved optic nerves in neurosurgical patients]

The article generalizes experience in the restoration of vision by direct stimulation of damaged optic nerves after operations for pathological conditions of the chiasmal-sellar region (tumors of the chiasmal-sellar region, optochiasmic arachnoiditis, damage of the optic nerve in the bone canal) in 111 patients. The therapeutic effect was favourable in two thirds of the patients. Indications are determined for the use of the method in various types, duration, and severity of the disease. The use of the method with due regard for the determined indications increases the reliability, degree, and rate of restoration of vision in patients who underwent operation.

[Indications for the use of a method of direct electrostimulation of the optic nerves in patients with pathology of the chiasmal-cell region]

The authors generalize the results of the use of the method of direct electrostimulation of optic nerves in 145 patients with pathology of chiasmal-cellar region (tumours, optochiasmal arachnoiditis, severe craniocerebral traumas with injuries of the bony optical canal) after the operations. The efficacy of the method was shown in 2/3 of observations with retention of residual visual functions. Differences in the efficacy of treatment of patients with various nosological forms of the disease have been revealed; indications for the use of the new method have been defined.

Malignant glioma of the optic chiasm eight years after radiotherapy for prolactinoma

A 41-year-old man had rapidly progressive visual loss caused by a malignant glioma that developed in the optic chiasm eight years after radiation therapy for a recurrent prolactinoma. Radiation-induced glioma should be considered as a cause of progressive visual loss in patients who have received irradiation in the region of the sella turcica.

Trigeminal schwannoma. Surgical series of 14 cases with review of the literature

A consecutive series of 14 patients with trigeminal schwannoma managed surgically at the Neurological Institute of New York since 1970 is reported. Nine women and five men (mean age 40 years) were diagnosed following a mean symptom duration of 33 months. Abnormalities of trigeminal nerve function were present in 11 patients on admission examination. Facial pain was a prominent feature in eight patients. Two patients, both with schwannomas arising from the trigeminal root, presented initially with typical trigeminal neuralgia. Additional cranial nerve palsies or cerebellar or pyramidal tract signs were noted in eight patients. The surgical approach to these tumors depends on their anatomical location. Four patients had tumors confined to the middle fossa, three patients had tumors limited to the posterior fossa, and seven patients had both supratentorial and infratentorial components of their tumors. Twenty operative procedures were performed on these patients, resulting in complete extirpation in six patients, nearly complete removal in seven patients, and partial removal in one patient. Adherence of the tumor to the lateral wall of the cavernous sinus or the brain stem precluded total removal. There was one postoperative death. In the immediate postoperative period, abnormalities of cranial nerves controlling the extraocular muscles were common. In general, these deficits were transient; however, some permanent loss of trigeminal nerve function occurred in nine patients. Two patients required tarsorrhaphy for neurotropic keratitis, and two patients underwent cerebrospinal fluid (CSF) shunting procedures for hydrocephalus or for a persistent CSF leak. The follow-up period ranged from 4 to 177 months (mean 47 months). The clinical features, anatomical considerations, and surgical approach to these rare tumors are discussed. A clinical review of 106 additional cases of trigeminal schwannoma, reported in the English literature since 1935, is also presented.