Atsushi Komatsuzaki

Clinical application of optokinetic nystagmus. Optokinetic pattern test.

Optokinetic nystagmus was provoked by constant acceleration followed by constant deceleration of an electrically controlled rotating drum. Nystagmus thus induced was recorded on a chart fed at the speed of 0.1 cm sec-1. A two-channel electronystagmograph was used with time constants of 6 sec and 0.015 sec, in order to approximate the former to eye deviation and the latter to eye speed. Eye speed of the slow phase of induced nystagmus in normals increases and decreases in close approximation to the angular speed of the drum, giving a cone-like appearance as illustrated. The authors denominated the patterns thus obtained “optokinetic pattern” (OKP), and the procedure, “OKP test”. OKP was modified by a weak spontaneous vestibular nystagmus in proportion to its degree. When optokinetic stimulation was applied to spontaneous nystagmus of ocular or central origin, OKP appeared to show characteristic patterns according to causative lesions. An analysis of these patterns, therefore, is expected to contribute to d...

Intratympanic Gentamicin Therapy for Meniere's Disease Placed by a Tubal Catheter with Systematic Isosorbide

In 1974 (6), 6 patients with incapacitating unilateral Menieres disease were given an empiric treatment with intratympanic gentamicin sulfate via the eustachian tube using a catheter with a small side-branch. These patients showed excellent results, gaining relief from vertigo over a 13-year period. Since 1980 (7. 8), we have treated patients suffering from Menières disease with isosorbide. When the patients could not be controlled by this therapy, isosorbide was given in addition to intratympanic gentamicin therapy using a tubal catheter. Of 75 patients with Menières disease who received gentamicin and isosorbide therapy, 41 could be evaluated by the classification of the American Academy of Opthalmology and Otolaryngology (AAOO) in 1987 (9). Three of these patients suffered from repeated attacks of vertigo for 2 years. However, all of them could be easily controlled by additional intratympanic gentamicin or isosorbide therapy on an out-patient basis. Thereafter, of a further 40 patients with incapacitating Menières disease who received gentamicin and isosorbide therapy, 15 could be evaluated by the AAOO classification. In summary, of the 115 patients with incapacitating Menières disease treated with intratympanic gentamicin after isosorbide treatment, 56 could be evaluated by the AAOO criteria from 1987 to 1990. These patients ranged in age from 21 to 79 years. Vertigo improved in 80% of the patients: 19 patients (34%) were group A. 22 patients (39%) were group B, 4 patients 7%) were group C and 11 patients (20%) were group D, of whom 9 patients required subsequent endolymphatic-mastoid shunt operations. This treatment also effectively controlled patients with bilateral Menières disease.

Otolithic influences on tonus changes of the extraocular muscles. A study on positional eye deviation and nystagmus.

Positional nystagmus is an important neurotological finding, and the head-hanging or up-side-down position is of specific importance in testing for positional nystagmus. In our experience the headhanging position produces the highest incidence of positional nystagmus. Indeed, a cat, two weks after a unilateral labyrinthectomy, does not show nystagmus in any other head position but head-hanging, which produces an intensive rotating nystagmus. The reason for this specificity of the head-hanging position is not known. In the present report, we will attempt to clarify this specificity of the headhanging position with respect to positional nystagmus.

Auditory brainstem implants: current state and future directions with special reference to the subtonsillar approach for implantation

In this article, the authors describe the current state of the auditory brainstem implant (ABI), comparing it to that of the cochlear implant (CI). The CI restores hearing by stimulating the cochlear nerve in the cochlea in patients whose deafness has been caused by inner ear disease; the ABI restores hearing by stimulating the cochlear nucleus of the brainstem in patients who are deaf because of bilateral cochlear nerve dysfunction. Up to now, about 500 patients worldwide have undergone ABI and had their hearing restored, most of whom suffer from neurofibromatosis type 2. Hearing performance, however, is not as good as that offered by the cochlear implant. To improve the quality of hearing, new techniques such as advanced coding strategies and penetrating electrodes, are now being introduced.

Subtonsillar placement of auditory brainstem implant

A 26-year-old female with NF2 underwent removal of an acoustic schwannoma via extended retrosigmoid approach with subtonsillar placement of the auditory brainstem implant. The patient had already shown palsy of the lower cranial nerves on the opposite side due to previous surgery. Differing from conventional routes such as the translabyrinthine and the retrosigmoid, the subtonsillar approach enabled us to observe the entire cochlear nucleus and avoid injury to the 9th and 10th cranial nerves when applying the electrode. Hearing in pure tone average was maintained almost at the preoperative level. We present a new use of this approach in placing the electrode and discuss its advantages.