Immunocytochemical studies and fiber-tracing studies were performed in adult cats to analyze the input-output organization of the interstitial nucleus of Cajal. Glutamate and aspartate immunoreactivity produced intense labelling of many cell bodies and terminals in the interstitial nucleus of Cajal and its adjacent reticular formation (Nint-RF). GABA immunoreactivity in the Nint-RF showed no labelling in cell bodies and strong labelling in the terminals. Some choline acetyltransferase-positive neurons and terminals, and a few substance P-positive fine fibers were also observed in the Nint-RF. Following WGA-HRP injection in the Nint-RF, many labelled neurons were found in the zona incerta (ZI), the Forel's field H (FF), the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), the Nint, the nucleus of the posterior commissure (NPC), the pretectum, the superior colliculus, the dorsal tegmental nucleus, the locus coeruleus, all cerebellar nuclei, the superior and medial vestibular nuclei, the dorsal group y, the nucleus prepositus hypoglossi (PH), and the pontomedullary reticular formation (PMRF). Many labelled terminals were observed in the thalamic central lateral and parafascicular nuclei, the ZI, the FF, the riMLF, the Nint, the NPC, the magnocellular red nucleus, the oculomotor nucleus, the trochlear nucleus, the facial nucleus, the medial and desending vestibular nuclei, the ventral group y, the PH, the PMRF, the medial part of the vetrolateral outgrowth, the rostral part of the dorsal cap, the caudal parts of the medial and dorsal accessory olive, and the spinal cord. The nomenclature of the cat mesodiencephalic structure was also described: the nucleus of Darkschewitsch, the nucleus accessorius medialis of Bechterew, the FF, the riMLF, the Nint, the suprarubral reticulal formation, and the subnucleus dorsomedialis and ventrolateralis of the parvicellular red nucleus. All of these nuclei fuse with each other, and the borders do not always remain apparent.
Lesions of the interstitial nucleus of Cajal (INC) in cats and monkeys result in severe impairment of the vestibulo-ocular reflex (VOR) in the pitch plane and vertical optokinetic reflex, and impairment of the ability to hold an eccentric vertical eye position after saccadic movement. The INC region of alert animals contains many burst-tonic and tonic neurons whose activity is closely correlated to vertical eye movement, not only during spontaneous saccades, but also during pitch VOR, smooth pursuit, and optokinetic eye movements. Although this activity is closely related to these conjugate vertical eye movements, it is different from oculomotor motoneuron activity. Because the INC region alone cannot produce eye-position signals, the INC is an essential component but not sole component of the velocity-to-position integrator for vertical eye movement. The INC and closely surrounding midbrain reticular formation contain a class of cells that have properties required for vertical burster-driving neurons. Chemical deactivation of these areas produces selective impairment of generation of vertical fast eye movement. These results indicate that the INC and nearby reticular formation may also be involved in generating vertical fast eye movements.
Recently, cases of vertigo have shown a tendency to increase, especially among middle age, and elderly patients. However, these patients often consult an internist or clinical neurogist. Therefore, I will touch upon the main points of diagnosing and treating patients with vertigo at an ENT clinic. As an approach to diagnosis, first, taking the history plays a great role, secondly, neurological signs are useful for distinguishing peripheral and/or central vertigo. Next, from among the vestibular function tests available, examination of eye movements, spontaneous nystagmus include gaze nystagmus, positional and positioning nystagmus, head shaking nystagmus and stabilometry are significant. In this paper, I report cases of vertigo or equilibrium disorders and discuss the treatment or prescription based on my clinical experience. Generaly, ENT doctors should treat patients with vertigo.
Two tests were administered to vertigo patients: the Cornell Medical Index (CMI) and the Manifest Anxiety Scale (MAS). 1. Vertigo patients at low risk of psychosomatic problems on CMI showed a tendency to be cured easier than those at high risk of psychosomatic problems on CMI. Vertigo patients at low risk of psychosomatic problems on MAS showed a tendency to be cured significantly more easily than those at high risk of psychosomatic problems on MAS. 2. This fact along with the fact that in the same patients, CMI and MAS test results showed no significant difference when tested during vertigo and during absence of vertigo supported the theory that CMI and MAS test results showed more psychosomatic problems in vertigo patients because of differences due to individual characteristics.
Recurrent attacks of vertigo without cochlear symptoms are called vestibular Meniere's disease (VMD), but the etiology has not yet been defined. VMD was diagnosed in 30 patients in Gifu University Hospital between 1987 and 1993. We reviewed the course of vertigo including cochlear symptoms. Hearing tests, electrocochleography and the furosemide VOR test were performed to investigate the etiology. 1. The patients were divided into four groups according to the course of vertigo. Less frequent attacks were observed in eight patients, while seven patients had periodic attacks. Fourteen patients had frequent attacks with in a few years. One patient had sporadic attacks but the frequency had increased recently. Fourteen of 30 patients had repeated attacks over a long period (6-40 years) without cochlear symptoms. 2. Electrocochleography and the furosemide VOR test were performed on 16 patients with VMD. Seven patients were positive for furosemide VOR test and negative for electrocochleography. There were four patients who were positive for both tests, while two patients were negative for the furosemide VOR test but positive for electrococ-hleography. Five of seven patients who had recurrent attacks over a long period without cochlear symptoms were positive for either test. These findings suggested that the etiology was endolymphatic hydrops. 3. In two patients, fluctuating hearing loss was noted on hearing tests. Therefore, they were diagnosed with Meniere's disease. 4. In one patients, tumor of the fourth ventricle was detected after 15 years.
This study attempted to discriminate stabilograms using a neural network that can learn with experience in patients with vertigo and equilibrium disturbances. Stabilograms obtained from 60 patients with disorders of the labyrinth, the cerebellum and the basal ganglia were used in this study. Area, length per second, length per unit area, displacements in X- and Y-axes and Romberg ratio of the stabilograms were used as input signals. The learning of the network was carried out with a specially designed program. 1 Stabilograms of patients with disorders of the labyrinth and the central nervous system were discriminated with an square error margin of 3.36E-02. 2 Stabilograms of patients with bleeding in the cerebellar vermis, bleeding or infarction of the cerebellar hemisphere and spinocerebellar degeneration were discreminated with an square error margin of 4.98E-03. 3 Stabilograms of patients with positive phenomena, negative phenomena a and b in Parkinson disease were discriminated with an square error margin of 4.98E-03. Neural networks obtained from learning using stabilograms were useful for discrimination of lesion sites and pathophysiologies of various diseases.
This study describes the characteristics of visual-vestibuloocular reflex (VVOR) and vestibuloocular reflex (VOR) in elderly subjects. Head and eye movements in passive horizontal head oscillations were examined with an "FAT-1" apparatus (reported by Tokita, 1993). Transfer function was calculated with head movements as input and eye movements as output. The examination was performed under the following 2 conditions, A) visual fixation to an earth-fixed target in the light (test for VVOR), B) image fixation to an earth-fixed target in the dark (test for VOR). From the data obtained in five healthy adults (twenties and thirties), the mean (M) and the standard deviation (SD) were calculated as the standards. The data obtained in twenty elderly subjects (65-91 years) were compared with the standards. The evaluation defined within M±1SD as "no change", within M±1SD-2SD as "tendency toward decrease" or "tendency toward increase", and beyond M±2SD as "decrease" or "increase." Results A) VVOR test (1) The breakpoint frequencies of the gain showed "decrease" or "tendency toward decrease" in all subjects. (2) The frequency ranges of 180°±10° were narrow in 14 subjects. B) VOR test (1) Patterns of gain curves were classified into 5 types. Gains did not show "decrease" or "tendency toward decrease" and slopes of 0.1-1 Hz and slopes at 0dB did not show "increase" or "tendency toward increase" in 5 subjects. These were classified as N type. Gains showed "decrease" or "tendency toward decrease" in low frequencies in 6 subjects. These were classified as L type. Gains showed "decrease" or "tendency toward decrease" in high frequencies in 2 subjects. These were classified as H type. Gains showed "decrease" or "tendency toward decrease" in low and high frequencies in 1 subjects. This was classified as LH type. Gains did not show "decrease" or "tendency toward decrease" in low frequencies and slopes of 0.1-1 Hz or slopes at 0dB showed "increase" or "tendency toward increase" in 6 subjects. These were classified as I type. This type was considered to show disorders of integration. (2)The frequency ranges of 180°±10° were narrow in 10 subjects. Conclusion In all elderly subjects, the visual-vestibuloocular function had decreased and the vestibuloocular function was classified into 5 types.
We retrospectively determined the efficacy of Semont's liberatory maneuver in 52 patients with benign paroxysmal positional vertigo (BPPV). Vertigo and torsional nystagmus, characteristic of BPPV, had been induced by the Hallpike maneuver at the time of diagnosis. Thirty of these patients were treated by Semont's maneuver after being informed in detail about the method. If vertigo reoccurred after treatment, they repeated the maneuver at home twice a day (after awaking and before going to bed) until vertigo disappeared. Patients received no medication and were followed until complete remission or for up to 1 year. The other 22 patients received either no treatment or were treated with medication only; they were followed for up to 9 years. Disappearance of nystagmus was ascertained for the first group only at our dizziness clinic. While most of these patients exhibited nystagmus lasting‹30 seconds (indicating the mechanism of canalolithiasis), two had nystagmus lasting›1 minute, a sign of cupulolithiasis-induced BPPV. Complete remission of BPPV occurred in 28 patients in the first group or 93.3%; 19 (68%) of these patients showed remission within 3 days. In the second group, the vertigo was resolved in only 9 of the 22 patients (40.9%). The difference in the remission rate of the two groups was significant (p<0.0001). Our results proved the efficacy of Semont's maneuver for treating not only the more common type of BPPV caused by canalolithiasis but also the less common type induced by cupulolithiasis.
Vestibular compesation in 3 patients with vestibular neuronitis was examined with static posturography (SPG) and kinetic posturography (KPG). SPG was recorded by a stabilometer during quiet standing and KPG was recorded by POLGON so that angular change of the shoulder on the frontal plane was measured during stepping in the same position. Our study showed earlier improvement of SPG than KPG. By vestibular training, the initial high levels of SPG and KPG decreased precipitously and in the case of sequela, the remarkably high level of KPG gradually decreased. The stepping test by POLGON combined with a stabilometry was useful for estimation vestibular dysfunction.
In 1962, Schuknecht reported that cupulolithiasis in the posterior semicircular canal caused by the otoconia detached from the otolithic membrane in the utricular macula was a possible cause of positional vertigo of the benign paroxysmal type (BPPV). In 1996, we reported that basophilic deposits adhered to the cupula in not only the posterior semicircular canals but also in the lateral and anterior semicircular canals. It is very interesting to evaluate the kinds of nystagmus caused by the cupulolithiasis and canalolithiasis in the lateral and anterior semicircular canals. In this study, the origin of direction changing positional nystagmus in the upper ear found in cases of benign paroxysmal positional nystagmus (BPPN) after head trauma was investigated. The subjects included two paients with direction changing positional nystagmus to the upper ear with BPPN after head trauma treated at the Neuro-otological clinic, Kitasato University Hospital between 1985 and 1996. It was suggested that the origin of this type of nystagmus as well as the various other types of nystagmus observed during their respective clinical courses was cupulolithiasis or canalolithiasis in the lateral semicircular canal and/or posterior semicircular canal. Although it was suggested that direction changing positional nystagmus from the upper or lower ear was caused by central vestibular disorder, especially that in the vermis, it was lil; ly that one case in this series was also caused by peripheral vestibular disorder.
A 14-year-old boy visited our hospital with positional vertigo after head trauma. The color of his left eardrum was dark blue from bleeding in the middle ear and the external aural meatum was deformed. CT showed fracture of the left temporal bone. Various types of positional and positioning nystagmus were observed. In some head positions, positional nystagmus with a secondary phase was noted. The secondary phase in the opposite direction followed the first phase of positional nystagmus, while the patient remained in the same head position. This secondary phase of nystagmus was not observed after 10 days. Positional vertigo disappeared after 2 months. We speculated that the secondary phase of positional nystagmus was due to the movement of the debris in the semicircular canal or to short term adaptation of the central or peripheral vestibular system and that the secondary phase of nystagmus was in-creased by transient dysfunction of the central nervous system due to head trauma.
N-methyl-D-aspartate (NMDA) receptors is thought to underlie certain types of learning and memory. In laboratory animals, treatment with NMDA receptor an-tagonist impaired spatial learning in a watermaze task. This study was undertaken to assess the behavioral effects of MK-801 [(±)-5-methyl-10, 11-dihydro-5H-dibenzo [a, d] cyclohepten-5, 10-imine maleate], on the acquisition of dynamic equilibrium in guinea pigs. We used the milk maze test (Morris et al, 1986) as a spatial learning test, and used the beam-walking test (Feeney et al, 1981, 1982) for dynamic equilibrium training. We observed that guinea pigs were able to traverse a narrow elevated beam to acquire dynamic equilibrium. We trained guinea pigs twice a day for a period of 12 days. Although MK-801, (0.07 mg/kg, i.p., n=6) impaired spatial learning during milk maze test, dynamic equilibrium during the beam-walking test (0.07 mg/kg, i.p., n=8) was not affected in the control group receiving an equal volume of saline injections. These results confirm that MK-801-induced impairment of spatial learning is due to the inhibition of NMDA receptors as previously reported. However, NMDA receptors may not play the same role in acquiring dynamic equilibrium, and this may be due to differences between the parts of the brain involved in learning and acquiring dynamic equilibrium.
To evaluate short and long term effect of treatment on Meniere's disease, the clinical course was examined in 25 patients treated with Isosorbide compared with the natural course without any treatment in 20 patients. Vertigo, hearing level, tinnitus and disability were assessed 4 and 8 week and 1 year after the start of clinical observation for patients respectively using the number of vertigo spells, 4-frequency pure tone average at 250, 500, 1000 and 2000 Hz, 5-staged score and 4-staged score based on the guidelines of Japan society for equilibrium reseach in Meniere's disease. Vertigo and disability in the treated group improved more significantly (P<0.05) than that in the group allowed to follow the natural course without significant change in either hearing level or tinnitus 4 week after starting observation. In contrast, there is no significant differences in the improvement of all four symptoms between the natural and treated groups 8 week and 1 year following starting observation. The effect of the drug was markedly demonstrated in the initial stage of disease. Evaluation of the short and long term effect of treatment on Meniere's disease should be performed on the basis of natural course which requires further examination to establish.