We attempted to set criteria for the diagnosis of vertebro-basilar insufficiency (V.B.I.) based upon neurotological findings by reviewing the literature and by analyzing our own clinical experience. The criteria are as follows : i) Vertigo or dizziness in association with symptomes caused by some disorder of the central nervous system, such as syncope, motor weakness, glove and stocking paresthesia, visual disturbances, altered consciousness, etc. ii) Abnormal eye movements in the gaze nystagmus test, which could indicate some lesion in the central nervous system. Quite often one might see a vertical down beat nystagmus in the head hanging position of Stenger's maneuver. iii) Saccadic or ataxic ocular pursuit in the eye tracking test, iv) Abnormal findings of the optokinetic after nystagums test, which could suggest some disorder in the central nervous system, usually decreased optokinetic after nystagmus v) Abnormal x-ray findings in the cervical spine, e.g. cervical spondylosis. Diseases which could cause vertigo or dizziness other then V.B.I. should be ruled out. A partient with abnormalities of all five items has definite V.B.I., one with four or three abnormal items has probable V.B.I., and one with two items has possible V.B.I., To establish these criteria of V.B.I., we analyzed 250 partients with vertigo experienced during the past three years. Peripheral vertigo was pressent in 39% and central vertigo in 23%. V.B.I. was diagnosed in 20% of the 250 patients. Our recent experience with 77 patients with V.B I. was also analyzed statistically.
A head-shaking test in generally used to provoke vestibular nystagmus. We tried two types of head-shaking tests. One is head-shaking by the examiner and the other is head-shaking by the patient. The elicited head-shaking nystagmus (HSN) was recorded on an electronystagmograph. At the same time acceleration of the patient's head was recorded by an accelerometer attached to the forehead with a headband and converted into acceleration. We studied 36 patients who had complained of vertigo. We found the angular acceleration of the patient's head ranged from 3000°/s2 to 11500°/s2, but there was no correlation between the appearance of HSN and the angular acceleration of the patient's head. There was no correlation between the slow phase velocity of HSN and the angular acceleration, either. Next, we investigated the correlation between canal paresis and the slow phase velocity of HSN. The coefficient of correlation was only 0.53, but there was a tendency that the severer the canal paresis was, the larger was the slow phase velocity of the elicited nystagmus.
Thirty seven patients of benign paroxysmal positional vertigo (BPPV) secondary to ear disease, whose diseased side was definite, were investigated clinically. The age of the patients ranged from 37 to 77 years.In 21 patents vertigo occurred in the critical position and in 19 of these the position was the same side as the disease. In all those with acute auditory or vestibular disturbance, unilateral canal function disturbance or unilateral sensory hearing disturbance, the critical position was the same as the side of the disease. Thirty one paients had positional nystagmus and in 19 of these the nystagmus was toward the affected side. In all patients with unilateral sensory hearing disturbance the positional nystagmus was toward the side of the disease, but of those with acute auditory or vestibular disturbance or chronic otitis media, only half had nystagmus toward the diseased side. Twenty one patients had positioning nystagmus when they moved from a sitting to a head hanging position and only seven of these had nystagmus toward the side of the disease. All of those with unilateral sensory hearing disturbance had nystagmus toward the non-affected side.
A 35-year-old female with symptoms of dysequilibrium was found to have bilateral medial longitudinal fasciculus (MLF) syndrome on the basis of neurotological tests and MRI findings. This patient began to note some dysequilibrium on standing or walking. Three days later, double vision on gazing towards the left side developed. Neurotological findings at the first examination demonstrated that the velocity of adducting saccades in right eye movement was markedly less than normal while the left eye was normal. A reduction in the velocity of adducting saccades in the left eye was observed two weeks later. Follow-up observation suggested that the main lesion of MLF was on the right side, with partial involvement of the left. At the same time no double vision on gazing towards the right was noted. However, electronystagmography revealed that the left MLF signs had become more pronounced than at the first examination. Subjective symptoms gradually disappeared. MRI with T2-weighted images revealed high signal intensity in the area of the right MLF at the level of the mid-pons, but CSF, serological viral examinations and CT were normal. These findings suggested an infarction of the mid-pons. Optokinetic nystagmus pattern (OKP) test and saccadic eye movement test (alternate two point gazing) were useful in monitoring the progress of MLF signs and evaluating the effectiveness of treatment.
Postrotatory nystagmus was analyzed by a 2nd order system model in 15 healthy nomal subjects. In postrotatory nystagmus the input into the semicircular canal is the impulse, so the model was Y (t) =A/T1-T2× (e-t/T1-e-t/T2) y (t) : slow phase velocity T1 : short time constant T2 : long time constant A : amplitude By means of the least square method, the variables T1, T2 and A were calculated with the aid of a microcomputer. The subject was seated in the dark on a rotating chair which was stopped at 80/sec2, 120/sec2 and 160/sec2. The slow phase of the electro-nystagmogram on DC ENG recording was calculated every 2 minutes and its values were used to calculate the variables of the model. T1 (short time constant) at 80, 120 and 160/sec2 was 0.37, 0.5 and 0.67sec and T2 (long time constaant) was 12.8, 12.19 and 11.13sec, respectively. These values could be converted into the frequency range of postrotatory nystagmus by the equation : f=1/2T. The frequency range corresponding to the above values is 0.01 to 0.4Hz, which is considered to be the normal frequency range in postrotatory nystagmus testing.
The frequency of movement of the center of gravity below 2Hz during Romberg's test was investigated in 202 normal subjects since it had been detected by our previous study that the sum of amplitudes of frequencies below 2Hz is about 80% of the total amplitude below 10Hz. The influence of sight (eyes open or closed) and of age and sex differences on body sway were studied statistically. The frequency of body sway in both lateral (X) and anterior-posterior (Y) directions was analyzed by the FFT method, and the sum of amplitudes at each frequency band of 0.1Hz below 1Hz and at each one of 0.2Hz between 1 and 2Hz was calculated. The mean values of the sum of amplitudes at each frequency band were compared. Increased body sway at frequencies of 0.1170 to 2.0085Hz and decreased body sway at frequencies of 0.0195 to 0.095Hz occurred when the subject closed his eyes. Sex differences were noted in X with eyes open in those aged 20-29 years, in X with eyes open or closed and in Y with eyes closed in those aged 30-39, in both X and Y with eyes open or closed in those aged 40-49, in X with eyes closed and in Y with eyes open or closed in those aged 50-59 and in both X and Y with eyes open or closed in those aged 60-69. Larger body sway with lower frequencies (less than 0.3Hz) and smaller sway with higher frequencies (0.3-2.0Hz) were observed in females than in males. Aging affected body sway in both sexes with eyes open or closed, especially in males in the 6th decade and females in the 5th decade.
“Audiokinetic Nystagmus” has been reported in many papers published in America and Europe during the past several years. However, clear and fine nystagmus has been described in very few of these papers. We devised a method of producing a sensation of motion and inducing nystagmus by moving sound stimulation from one ear to the other ear repeatedly. Our new equipment is more effective than the methods described in many former papers. Our new method demonstrated nystagmus in a few patients without nystagmus by ENG recording and observation both with and without Frenzel spectacles.
As previously reported, we found that older subjects have a reduction of slow phase velocity at higher target speeds in optokinetic nystagmus (OKN). In this article we discuss the influence of age on the other routine vestibular tests in a comparison of the data from different age groups : 35-44 years and older than 65 years. 1. There were no significant reductions of the three parameters in the caloric test or in the fixation supression test. 2. In the stabilometry test, the length of the body sway was significantly increased in the elderly group. On the other hand, the area of body sway showed no significant difference, which indicates the need for a feedback system in which the body sway can be minimized by fine movement control. 3. There was no definite interrelationship between OKN and stabilometry. 4. The standard deviations of those equilibrium test-results were larger in the elderly group than in the younger group.
The course of spontaneous and neck vibration nystagmus in two patients after unilateral labyrinthectomy was investigated to clarify the role of cervical input in vestibular compensation. In one patient whose velocity of spontanious nystagmus decreased after labyrinthectomy, the velocity of neck vibration nystagmus increased after the operation. In another patient whose velocity of spontaneous nystagmus did not decrease, the velocity of neck vibration nystagmus did not increase. These results indicate that the modulation of sensory input from the neck proprioceptors by neck vibration induced marked nystagmus in the first patient who should have gained better vestibular compensation than the second patient after hemilabyrinthectomy. Thus, it can be speculated that cervical input plays an important role in the process of vestibular compensation.
From among the 847 ears operated on during the past ten years, 56 with labyrinthitis and/or labyrinthine fistula were studied. Labyrinthine disorders were due to chronic otitis media with cholesteatoma in 43 ears and without cholesteatoma in 13 ears. Labyrinthine fistula was found in 41 ears, 36 (83.7%) with cholesteatoma and 5 (38.5%) with chronicotitis media. The location of the fistula was the lateral semicircular canal in 37 ears, the anterior semicircular canal in 2 ears, the posterior semicircular canal in 1 ear, the common crus in 2 ears, the utricle in 2 ears, and the cochlea in 2 ears. The fistula was treated by one of three methods; 1) covering of the fistula with Gelfoam after removal of the granulation around it in 26 ears; 2) covering of the fistula with the temporal fascia in 11 ears; 3) labyrinthectomy in 4 ears. Vertigo and dizziness decreased or ceased after the operation. Tympanoplasty was performed in some cases, and the prognosis for hearing was satisfactory.
A follow-up study was performed with the pendular sinusoidal rotation tests (VOR-test, VVOR-test) in patients with vertigo. The following results were obtained after relatively long clinical observation. 1. The VOR-DP reflects the clinical status of the patients. The VOR and VVOR test battery is useful in evaluating vestibular compensation. 2. In patients with acute total loss of labyrinthine function, vestibular compensation occurred 2 weeks after the onset. 3. VOR and VVOR-tests are appropriate for following the progress of the disease.
A-19-year old man had complete gaze nystagmus and rebound nystagmus in all directions. Other neurological and neurotological examinations showed myoclonus of the rectus abdominis muscles, direction-changing positional nystagmus to the lower ear and vertical positioning nystagmus, saccadic pursuit, impaired OKN and abolition of visual suppression. He had a 3-year history of thinner sniffing, and NMR-CT showed cerebellar atrophy. Lesions of the posterior vermis, the flocculi, the dentate nuclei and the efferent pathway and the reticular formation in the midbrain and the pontine tegmentum were presumably responsible for these findings.
Vestibular and auditory funtion tests were performed in patients who had received streptomycin sulfate (SM) injections. The caloric test and pure tone audiometory were chosen as tests of vestibular and auditory functions, respectively. The results of the caloric tests were correlated with auditometry results, age, dose of SM and renal function. The reduction of the maximum slow phase velocity was 0.70±0.15°/sec/g (mean±SE). There seemed to be a relationship between the reduction of the maximum slow phase velocity of caloric nystagmus and the total dose of SM, but the hearing threshhold did not change when the total SM dose was increased. The reduction of the maximum slow phase velocity of caloric response in the older patients seemed to be larger than in the younger patients. The weekly dose of SM and the renal function were not related to the vestibular function. These results suggest that the caloric test is useful in detecting not only vestibular dysfunction but also hearing impairment. It is important to check the response to the caloric test to prevent hearing loss due to SM injections.
A study of hearing impairment in 292 patients with Ménière's disease revealed that with advancing age hearing acuity was gradually lost. However, one must take into account the physiological decline in hearing due to aging when evaluating the results of audiometry. Hearing loss due to aging was calculated and subtracted from the raw threshold level in each cases. Deterioration in hearing was far greater in the first 5 years of Ménière's disease than in subsequent years, and the difference of threshold from that of the other ear was higher at 500Hz than at 8000Hz. The hearing loss was characterized by fluctuations in the level of hearing, particularly at 500Hz. Nevertheless, as the disease progressed, the degree of fluctuation in patients who had suffered for more than 15 years became less marked at low tone frequencies. Among the 292 patients investigated, 18% cases had bilateral involvement. The incidence of bilateral disease rose with the duration of illness.
We reviewed the details of the clinical history of 31 patients with vertigo who had been operated on by (modified) radical mastoidectomy. Fifteen patients continued to experience dizziness, which was divided into three types. 1) paroxysmal vertigo (3 cases), which resembled the first attack of Meniere's disease; 2) positional vertigo (5 cases); and 3) unsteadiness, provoked by rapid body movement or visual fatigue in some patients. Although the main cause of these dizzy spells was labyrinthitis due to the accumulation of keratinizing substance in the open cavity, a more detailed explanation seemed to be possible, according to the results of the examinations. The mechanism of paroxysmal vertigo, non-progressive endo-lymphatic hydrops (Schuknecht) seemed to be the most likely one, and positional vertigo might be explained by degenerative changes in the membranous labyrinth. However, merely pathological changes of the labyrinth could not account for the dizziness of type 3. The percentage of patients who continued to experince dizziness (48%) was higher than in former reports. Moreover, the percentage of those with the true rotatory vertigo types 1 and 2 among these 15 patients (53%) was higher than in former reports, although these reports described mainly preoperative findings. Our results should be considered when canal wall down methods are employed in order to prevent chronic infection from penetrating into the labyrinth during mastoidectomy.
A 52-year-old female had recurrent episodes of tinnitus, hearing less and vertigo. When systemic edema accompanied the vertigo attack, tinnitus and hearing less disappeared--the characteristic course of Lermoyez's syndrome. Overhydration with drinking water could induce systemic edema, nystagmus and improvement of hearing, while dehydration with furosemide caused the impatred hearing and disapparance of edema and nystagmus. The results of the hydration and dehydration tests were directly opposite to those in patients with Meniere's disease, in which the etiology is endolymphatic hydrops. Therefore, we concluded that endolymphatic collapse was responsible for the characteristic course of the symptoms in our patient. The same mechanism of water metabolism is probably the cause of both Lermoyez's syndrome and idiopathic edema.
Endolymph-perilymph shunts were produced in 20 guinea pigs with endolymphatic hydrops induced by the silver nitrate method. The shunt was created between the scala media and the scala tympani through the basilar membrane in the basal turn of the cochlea. At various intervals (3 hours-27 days), animals were sacrificed and prepared for pathological examination. In 10 of the 20 animals the shunt was visible, varying from a small fissure to 200 microns in width. In the other 10 animals the shunt had probably healed over, because fracture lines were often observed. In those examined 3 hours to 3 days after operation, there was slight membranous collapse. After 7 to 27 days however, the animals showed hydrops even if the shunt was still patent. Severe degenerative changes of Corti's organ and severe atrophy of the stria vascularis were observed adjacent to the shunt area. The temporal bone of a patient with otosclerosis and Meniere's disease was also studied. Otosclerosis had invaded the lateral wall of the cochlea inducing atrophy of the spiral ligament, stria vascularis and basilar membrane to create a natural endolymph-perilymph shunt between the scala media and the scala tympani. This structure resembled the shunt produced experimentally in guinea pigs. The patient had suffered from vertigo which later disappeared although hearing loss was severe. The shunt may have worked as a pressure-releasing fistula.
H2 clearance in the endolymphatic and perilymphatic systems of the inner ear was measured simultaneously with a bi-channel hydrogen clearance monitor. Two special hydrogen-sensitive microelectrodes were applied to a small hole made in the stria vascularis and round window. All H2 clearance curves revealed monoexponential functions. The half life times (T1/2) of both endolymphatic and perilymphatic H2 clearances of 10 guinea pigs were examined in order to study these metabolic differences. The half life time of the endolymph was significantly shorter than that of the perilymph in non-treated animals. The influence of furosemide was also examined. The half life time of H2 clearance in 10 guinea pigs was not significantly different before and after the infusion in either the endolymph or the perilymph. A personal computer (NEC PC-9801) and soft ware made by ourselves used to analyze these data.
A 29-year-old female had complained of unsteady gait for 6 years. Infection of the spinal cord was diagnosed. Traction of the lower limbs and tendonplasty of the Achilles tendon had been performed without improvement. Unsteady gait was followed gradually by difficulty in speech, numbness below the mammary line, and weakness of the lower extremities. She could not stand without support. She was referred to the ENT department, because of dizziness and inability to follow moving objects visually. ENG rerealed the following ocular motor abnormalities : 1. primary position upbeat nystagmus 2. rebound nystagmus 3. failure of fixation-suppression of caloric nystagmus 4. deranged pursuit eye movements 5. limitation of slow phase OKN velocity These ENG findings suggested cerebellar and brainstem lesions. A CT scan through the posterior fossa showed brainstem atrophy with enlargement of the cistern of the midbrain and the pons. Signs of cerebellar atrophy were equivocal. The neurological and neuroradiological findings led to a diagnosis of spinocerebellar degeneration. The ENG test can be useful in the detection of central nervous system disorders.