C. R. Pfaltz

A randomized, double-blind, placebo-controlled study of dextran/pentoxifylline medication in acute acoustic trauma and sudden hearing loss

The effectiveness of any therapy in acute acoustic trauma or sudden hearing loss of unknown origin has not been demonstrated convincingly. The assessment is difficult because of a relatively high rate of spontaneous recovery. Nevertheless, many different forms of treatment are recommended. We tested one form, treatment with rheoactive substances, in a prospective, randomized, double-blind trial and compared treatment with (a) infusions of dextran-40 with pentoxifylline, (b) saline infusions with pentoxifylline, and (c) saline infusions with placebo medication. Pure-tone hearing thresholds served as control parameters and were taken before treatment and at 1 and 4 weeks after the onset of therapy. Three hundred eighty-two patients were included in the trial, 331 (87%) could be analyzed, 184 patients were treated because of sudden hearing loss, 147 because of acute acoustic trauma. The three treatment groups were comparable in their basic characteristics including the amount of initial hearing loss. In patients with sudden hearing loss, no significant differences of hearing recovery were detected between the three treatment groups. Hearing recovery was also similar in patients with acute acoustic trauma. A power analysis of the study revealed that possible true treatment differences of a hearing recovery of 10 dB would have lead to significance with a probability of over 90%. It is concluded that there were, in fact, no clinically relevant differences in hearing gains of sudden hearing loss or acute acoustic trauma between treatments with saline infusions together with placebo medication and treatment with dextran-40 and/or pentoxifylline.

Preoperative and postoperative auditory and facial nerve function in cerebellopontine angle meningiomas.

Preoperative and postoperative facial nerve and auditory function were reviewed retrospectively in 13 cases of cerebellopontine angle meningiomas. According to their location within the posterior fossa and with special reference to the internal auditory canal, they were classified into a premeatal and a retromeatal group. All the tumors were removed by an otoneurosurgical team by use of a retrosigmoid approach. Postoperative results (1 year after operation) were compared within the two groups with respect to preservation of hearing (normal hearing in 31% and preservation of preoperative hearing in 69% of the cases) and facial nerve function (no or mild postoperative impairment in 69% of the cases). Both preoperative and postoperative impairment of facial nerve and auditory function prevailed in the premeatal group. For preservation of vital vascular and central nervous structures, subtotal resection with consecutive fractionated radiation therapy had to be performed in 30% of the cases. Our results provide substantial evidence that in cerebellopontine angle meningiomas a precise preoperative study of tumor location will assist in improving individual operative strategy and thus postoperative functional results.

Vestibular Compensation: Physiological und Clinical Aspects

Vestibular compensation is achieved by means of a multisensory substitution process. Experimental and clinical observations indicate that patients, suffering from a sudden loss of vestibular function, should get an early multisensory training in order to induce adaptive changes as soon as possible.

Effect Of Repetitive Optokinetic Stimulation Upon Optokinetic And Vestibular Responses

The question of whether habituation of optokinetic nystagmus occurs with repetitive stimulation was studied in a series of trials in 15 human subjects. The results indicate that there is no response decline characteristic of habituation, but on the contrary a constant and definite increase of optokinetic response, interpreted as the result of a positive learning process. The latter does not influence or modify the caloric, rotatory and galvanic vestibular responses.

Temporal bone pneumatization

: This present study is based on the results of a planimetric investigation of temporal bone pneumatization in 73 children (with and without middle ear pathology). Radiologic and clinical follow-up studies indicate a definite inhibition of pneumatization due to chronic secretory or recurrent suppurative otitis media. This process is partially reversible if the underlying pathologic ventilation of the middle ear spaces is cured by an adequate treatment, such as direct adenoidectomy and/or long-term middle ear ventilation (6 months indispensable).ZusammenfassungIn der vorliegenden Studie wurde die Ausdehnung der Felsenbeinpneumatisation ohrgesunder und ohrkranker Kinder planimetrisch berechnet. Wir stellten dabei fest, daß bei rezidivierenden Otitiden oder Seromukotympanon mittels einer Langzeit-Paukendrainage eine deutlich stärkere Zunahme der bisher gehemmten Pneumatisation erfolgt als nach alleiniger Adenotomie. Die radiologischen und klinischen Befunde weisen darauf hin, daß rezidivierende Mittelohrinfekte in früher Kindheit zu einer gehemmten Pneumatisation führen, diese aber nach adäquater Behandlung mit Paukendrainage und/oder Adenoidektomie wiederum fortschreitet.SummaryThis present study is based on the results of a planimetric investigation of temporal bone pneumatization in 73 children (with and without middle ear pathology). Radiologic and clinical follow-up studies indicate a definite inhibition of pneumatization due to chronic secretory or recurrent suppurative otitis media. This process is partially reversible if the underlying pathologic ventilation of the middle ear spaces is cured by an adequate treatment, such as direct adenoidectomy and/or long-term middle ear ventilation (6 months indispensible).

Studies on the anatomy of the facial nerve.

The present study on the anatomy of the human facial nerve is based on the results of a series of gross dissections, and histological and electro-diagnostic examinations. From our findings it follows that there is a definite spatial orientation of the peripheral branches in the facial nerve trunk. The results of the morphologic studies are in agreement with those obtained by electric stimulation combined with electromyography.

The optokinetic test: Interaction of the vestibular and optokinetic system in normal subjects and patients with vestibular disorders

ZusammenfassungIn der vorliegenden Arbeit wird über die Ergebnisse optokinetischer Prüfungen bei normalen Versuchspersonen (50) sowie bei Patienten mit peripheren und zentralen vestibulären Funktionsstörungen (100) berichtet. Daraus geht hervor, daß der optokinetische Nystagmus, welcher durch eine Reizung der gesamten Retina ausgelöst wird (foveo-retinaler OKN), nicht auf dem selben Reflexmechanismus zu beruhen scheint, wie der durch gezielte Stimulation der Fovea hervorgerufene foveale OKN. Die diagnostische Bedeutung des foveo-retinalen OKN ist höher einzustufen als diejenige des fovealen OKN, da er nur in geringem Grade durch die Aufmerksamkeit bzw. die Vigilanz der Versuchsperson beeinflußt wird. Die Untersuchung des foveo-retinalen optokinetischen Nystagmus erweist sich im Hinblick auf die Differentialdiagnose zwischen einer peripheren und zentralen vestibulären Funktionsstörung als außerordentlich wichtige und zuverlässige experimentelle Methode.SummaryIn 100 patients showing different lesions of the peripheral vestibular system and of the CNS, the influence of spontaneous vestibular nystagmus on optokinetic nystagmus was investigated. Considering the large interindividual differences in the results of vestibulo-visual interaction, the actual values of OKN slow-phase velocity obtained by visual stimulation are only of limited diagnostic value in a single case. However, by averaging the results obtained from various nosologic groups of patients very different but distinct patterns of vestibulo-visual interaction can be demonstrated: The diagnostic importance of quantitative assessment of optokinetic nystagmus is demonstrated by a statistical evaluation of test results obtained in normal subjects as well as in patients with peripheral and central vestibular disorders. The most important diagnostic parameters of a pathologic foveo-retinal optokinetic response are directional preponderance of slow phase velocity and gain of OKN. Increasing target velocity with decreasing gain clearly indicate the presence of a severe brainstem lesion involving the entire oculomotor control system which provides the coordination of head and eye movements.

Central compensation of retrolabyrinthine vestibular lesions.

The present study is based on the results of repeated vestibular examinations in a group of patients with retrolabyrinthine lesions. Central vestibular compensation is found to be based on the three following mechanisms: 1. Accommodation. This mechanism seems to depend entirely on the integrity of the efferent vestibular system. 2. Recovery. 3. Central regulation. Impaired peripheral vestibular function is substituted by optic-visual and somato-sensory mechanisms. It seems to depend mainly on the functional integrity of the cerebello-vestibular fibre connections.

Classification of peripheral and central (pontine infarction) vestibular deficits. Selection of a neuro-otological test battery using discriminant analysis.

The results obtained from a complete neuro-otological test battery were examined statistically in order to select measurement variables which would optimally indicate significant differences between four groups: normal patients, patients with partially compensated unilateral peripheral vestibular deficit, patients with an acoustic neurinoma and patients with central (brainstem) vestibular deficit. A stepwise-discriminant analysis was performed on measurements of slow-phase velocity obtained from each test. The primary measurements selected to assign a subject optimally to one population were the canal paresis (CP) of the caloric test, the eye-tracking gain contralateral to the deficit for a 15 deg/s stimulus, the gain asymmetry for optokinetic nystagmus with a 30 deg/s stimulus, and the level of spontaneous nystagmus. The resulting classifications were 100% correct for normal and central deficit patients. However, the division between peripheral deficit and acoustic neurinoma patients overlapped causing about 30% false classifications of neurinoma patients: some 20% of the peripheral deficit patients were classified as normal. If the CP was not available the discriminant analysis substituted the rotating chair response for 5 deg/s2, in place of CP. This substitution caused a 10 to 20% decrease in classification accuracy.

Studies on Habituation of Vestibulospinal Reflexes

The influence of repetitive applications of optokinetic and vestibular stimuli upon the vestibulospinal responses, measured by the stepping test, was investigated both in an optokinetic training and vestibular habituation test series. Repeated applications of optokinetic and vestibular stimuli modified the rotation angles of the stepping test, i.e. vestibulospinal responses, resulting in a response decline of rotation angles which was still present after 1 month.