Plugging of the semicircular canal creates a special condition, that is "the end-organ sends out normal static signals without dynamic modulations." Recent achievements in our studies have been due to accurate 3-dimensional stimulators and also to accurate techniques for 3-dimensional recording of eye movements. When a canal is plugged on a spot away from both the ampulla and the utricular orifice with little turbulence in the endo- and perilymphatic spaces, an ideal canal plugging without end-organ damage should result. There are, however, several questions concerning this experiment: 1) Histo-pathological studies under light microscopy may not be sufficient in detecting the slight end-organ damages. 2) Does canal plugging result in a complete absence of dynamic inputs of any kind from the plugged canals? 3) Are paired-canal pluggings less disturbing to the CNS than unpaired-canal pluggings? 4) Are paired-canal pluggings useful for the study of canal-canal interaction and canal-otolith interaction, while un-paired-canal pluggings, useful for entirely different purposes?
Two cases of horizontal eye movements disorders due to pontine lesions are reported and their clinical symptoms described. Case 1, a 52-year-old female, showed right lateral gaze paralysis together with right facial paralysis, vestibular dysfunction and scanning speech after surgery on an epidermoid cyst in the 4th ventricle. Case 2, a 56-year-old female, displayed right lateral gaze paralysis combined with right facial paralysis, vestibular dysfunction, right deafness and left hemiplegia following pontine hemorrhage. The right lateral gaze paralysis of both cases were analyzed and speculated to have resulted from combined disorders of the right abducens nucleus, the right PPRF (paramedian pontine reticular formation) and the right MLF (medial longitudinal fasciculus) in the pontine tegmentum.
We describe three patients complaining of hearing disturbance associated with le sion in the anterior inferior cerebellar artery. Case 1: a 71-year-old male with hypertension complained of dizzines with right facial nerve paralysis. Although pure tone audiometory was slightly worse on the right than on the left, auditory brainstem response showed no response. MRI revealed infarction in the right AICA territory and MR angiography revealed a defect of in the right AICA. Case 2: an-80-year-old female with a 40-year history of diabetes mellitus complained of vertigo with left profound hearing loss. Neurological examination showed left upper and lower muscular weakness. MRI revealed multiple spotty high density area, however MRI did not visualize the inner ear well enough to identify AICA territory infarction. Case 3: a 58-year-old female complained of left hearing loss with vertigo. Otoneurological examination showed profound sensorineural hearing loss and positional horizontal nystagmus beating toward the ceiling. MRA revealed Dolico artery. We suspected that she had circulatory insufficiency in the AICA territory.
To quantify the normal range of visual fixation, active head movements and compensatory eye movements toward a near target were measured during head rotation in 10 normal adult subjects. The data were recorded by a photodetector for head movements and by an electronystagmograph for eye movements under the following conditions: subjects were instructed to track a 1-m distant visual target, which was moved horizontally at an amplitude of 10° and 20° over a broad frequency range changing from 0.1 to 10.0Hz for 40s in succession. The recorded data of head and eye movements were analyzed with the power spectrum analysis technique for comparison. When the frequency exceeded 5.0 Hz at an amplitude of 10°, head rotation became difficult. When the frequency was 3.8 Hz at an amplitude of 10°, the mean power spectrum of eye movements was significantly higher than that of head movements. At an amplitude of 20°, a significant difference in mean power spectrum was observed when the frequency was 1.2 Hz. The phase was stable from 0.5 to 3.0 Hz at an amplitude of 10°, and from 0.5 to 1.3 Hz at an amplitude of 20°. In quantifying visual fixation during active head rotation, it was easier and required less time to use the broad frequency range changing in succession over a short time. This method seems to be thoroughly applicable for clinical examinations.
This study investigated the characteristics of balance in persons with hearing impairment (PHI), and analyzed the effect of their vestibular function on balance. The subjects were 22 PHI aged 12 to 20 years. Balance abilities were evaluated by body sway and balance exercises (beam walking and one foot balancing). Beam walking was measured with eyes open and body sway and one foot balancing were measured with eyes open and with eyes closed. (1) Magnitude of body sway in PHI was similar to that in non-handicapped persons (NHP) under both visual conditions. Also, scores of beam walking and one foot balancing with eyes open in PHI were similar to those in NHP. One foot balancing scores with eyes closed in PHI, however, were lower than those in NHP. (2) From these results and the earlier study, it is suggested that the vestibular function does not affect slight body sway but does play a role in greater sway.
Endolymphatic hydrops was induced in the left ear of 10 albino guinea pigs by obliterating the endolymphatic duct and sac, and the effect of isosorbide was examined. DPOAEs at 4, 6 and 8 kHz were measured three times, ie before surgery, one to two weeks after surgery and one to two hours after oral administration of isosorbide. DPOAEs recorded one to two weeks after surgery exhibited a significant reduction in amplitude at 4 and 6 kHz, while there was no change at 8 kHz. According to our previous study, this finding indicates that the induced hydrops is still in the early stage where the threshold of the compound action potential has not yet elevated. Oral administration of isosorbide restored the amplitude of DPOAEs to the preoperative level at 4 and 6 kHz. The results obtained in the present study indicates that isosorbide is quite effective in preventing the development of hearing loss in the early stage of hydrops.
This study investigated the developmental changes in head movement during stepping in toddlers. The subjects were 39 toddlers aged 4 to 6 years, and 13 adults aged 19 to 22. Vertical and horizontal head movements during ordinary stepping were measured with a position-sensor. The length of head movement for 1024 points of A/D converted data at 20.48 sec intervals was calculated as an index of magnitude for each of the 2 types of vertical and horizontal movements. Results were as follows: (1) The horizontal magnitude was nearly equal between 4 and 5years, and significantly decreased at 6years. (2) The vertical magnitude didn't change from 4 to 6years.
We surveyed elderly patients over 65 years of age who were treated for vertigo or dizziness in our Clinic between 1984 and 1993. There was a significant increase from 17.2% in the earlier 5-year period to 21.7% in the later period. This increase exceeded the growth in the elderly population in Nagasaki. Female patients showed a greater increase than male patients, especially among patients in their 70's. There were various causes in these aged patients, but BPPV and Cerebro-vascular disorders were common. From these results, vertigo or dizziness in aged patients might be prevented by suitable treatment of factors causing Cerebro-vascular disorders, such as hypertension.
Therapeutic results of inner ear anesthesia were evaluated in 35 patients with medication resistant Menière's disease. A mixture of 0.5 ml 4% lidocaine and 2 mg dexamethasone was transtympanically injected into the middle ear cavity. Since this inner ear anesthesia therapy transiently depresses labyrinthine function, the patient has to be hospitalized. The injection was performed 4 times at 4-day intervals. The criteria for evaluating the therapeutic effect on vertigo were recommended by the committee of the Japanese Society of Equilibrium Research. This is a revised version of the criteria for evaluation by AAO-HNS, by changing the 2 year observation period in AAO-HNS to 1 year. In this method, the frequency of vertigo after treatment was compared with that before treatment. A numeric value was calculated by dividing the mean monthly frequency of vertigo for one year after treatment by the mean monthly frequency of vertigo for 6 months before treatment and multiplying by 100. The results were categorized into 5 grades and complete recovery was seen in 37%, substantial recovery in 46%, limited recovery in 6%, insignificant change in 9% and deterioration in 3%. A positive effect from treatment including complete and substantial recovery was seen in 83%. A sig-nificant correlation between the hearing level and therapeutic effects was recognized. Improvement of the healing level by 10 dB or more was seen in 6 patients, changes within±10 dB were seen in 26, decrease by 10 dB or more was seen in 3. So no change was seen in 74%. The positive effect of inner ear anesthesia on tinnitus was 83% immediately after treatment, and 69% one year after treatment. Consequently, inner ear anesthesia appears to be a valuable treatment well worth trying prior to surgical therapy for resistant Meniere's disease.
Benign paroxysmal positional vertigo (BPPV) is the most common 'provoked vertigo'. In Japan, there has not been any physiotherapy attempted for this clinical entity and this is the first report implementing the method described by Epley. Two techniques were used in this small preliminary series. One was the conventional Epley's maneuver using a vibrator and the other involved the same head positions without a vibrator but tapping the mastoid bone with fingers or fist. Fifteen BPPV patients with classic nystagmus were selected and underwent therapy by one of the two methods. In thirteen of the fifteen patients, no further positioning vertigo occurred after a single session. But two patients said that they felt light dizziness due to other unknown causes, which were not associated with changing the head position. One was completely cured after three sessions. In one patient, BPPV partially remained. As the patient had concomitant heart disease, she could not undergo another session. None of the patients were unchanged or worse after the treatment. Epley's maneuver either with or without a vibrator showed excellent results. We recommend that this be the first choice of treatment for persistent BPPV.
We studied autoregulation in the brainstem and the inner ear. Using laser-Doppler flowmetry, we measured brainstem blood flow (BBF) and cochlear blood flow (CoBF) with BP alteration in rats. With induced hypotension by exsanguination above the critical BP level, BBF tended to be preserved supposing the existence of autoregulation. Although CoBF was slightly decreased, a nonlinear relationship to BP also suggested the effect of autoregulation. When BP was raised by reinfusion, after a large temporary increase and recovery, BBF and CoBF showed small increases, and the fact also suggested the existence of autoregulation. The latency of recovery from a temporary increase in BBF was shorter than that in CoBF. These results supposed that both the brainstem and the inner ear showed autoregulation of blood flow, and the efficiency of regulation in the brainstem was superior to that in the inner ear.
Since he received a stranglehold during a judo bout, the patient had experienced repeated episodes of paroxysmal vertigo. The patient was a 16-year-old male with a chief complaint of horizontal oscillating vision. Plain X-ray examination during the initial consultation did not show a definite fracture of the styloid process. Balance testing disclosed no significant finding. Helical scan CT delineated a fracture in the center of the left styloid process and anterior deviation of the fractured segment. The mechanisms of oscillopia in this patient were considered to be the following; 1) the fractured segment of the styloid process stimulated the tensor muscle of the velum palatini causing a spasm, and induces symptoms of the inner ear, which is similar to the mechanism of Costen syndrome. 2) the fractured segment stimulated the autonomic nerves near the carotid artery, especially the vagal nerve when he raised his head, and induces transient hypotension, which caused an ischemic brain stem lesion. The present case was an extremely rare case involving a fracture of the styloid process with paroxysmal vertigo.