Equilibrium function in the cerebellum (vestibulo-cerebellar system) is deteriorated by medicinal actions (MAs). In the Romberg posture, the center of gravity, which was measured every 50 msec by stabilometry, appeared to shift with alcohol ingestion. In the previous study, a locus in the center of gravity (statokinesigram) was converted to a value of statistical indices such as area of sway, total locus length, and locus length per unit area, although these indices could not always distinguish between the statokinesigrams sampled from 7 healthy young males presenting with and without MAs. This measurement was made with an AMTI force plate. In this study, a statistical index “translation error” was estimated in a d-dimensional embedding space in order to compare statokinesigrams recorded before and after the ingestion of doubly diluted brandy in 30 s (1≤d≤10). We succeeded in validating a stochastic differential equation as a mathematical model of the body sway. The randomness in the model was preserved after alcohol intake and significantly increased in the medial/lateral direction. Visual information referred by the control system of standing posture might be regarded as an external forcing associated with the MA. This method is considered to be useful to diagnose the disorders of the vestibulo-cerebellar system.
Fourth ventricular injections of endothelin-1 (30-100 ng) induced rotation along the long axis of the body (barrel rotation) in rats. N-methyl-D-aspartate (NMDA, 1-10 μg), an excitatory amino acid, and muscimol (1-10 μg), a GABAA receptor agonist, also evoked barrel rotation. Bath application of NMDA and muscimol on the spontaneous tonic discharge of medial vestibular nucleus (MVN) neurones in rats, showed excitatory and inhibitory responses, respectively. Interestingly, endothelin-1 did not affect the spontaneous discharge rate of MVN neurones when applied either as a 60 s pulse or when the drug was continuously perfused for a period of 5 min. Reciprocal relationship between excitatory and inhibitory inputs, such as glutamate and GABA receptor agonists, for MVN neurones may be crucial in inducing barrel rotation. The results also suggest that the barrel rotation induced by endothelin-1 is mediated by its modulatory effects on indirect pathways to the vestibular nucleus.
Standing posture regulation system is considered to be complex systems. Body sway appearing in standing posture was investigated from this point of view. The sway of the body center of the gravity in upright standing was recorded with eyes open and closed each 60 seconds using a stabilometer in 10 normal subjects. From time series data obtained, attractor (embedding dimension: 3), correlation dimension, Lyapunov exponent, Lyapunov spectrum and the largest Lyapunov exponent were calculated using a chaos analysis program. Correlation exponent was not saturated on an increase of embedding dimension (from 2 to 7). The result indicated that attractor did not have self-similarity. The result suggests that the irregular fluctuation observed in standing posture is not deterministic chaos. Lyapunov spectrum indicated that nature of attractor was torus and random. The result suggests that the sway appearing in standing posture is constructed from quasi-periodic and random movement. The largest Lyapunov exponent indicated that orbital instability is high in right-left sway than forward-backward sway. The control mechanism of standing posture differs in right-left and forward-backward directions. The analysis considering the complex systems provide information on postural control that cannot be obtained by conventional method.
Patients with vertigo caused by psychological problems have increased in recent years. It has been reported that many outpatients with vertigo also suffer from depression. Selective serotonin reuptake inhibitors are widely used for the treatment of depression because of their efficacy and relatively favorable side-effects profile compared to those of tricyclic antidepressants. We used Paroxetine to treat patients with vertigo who were diagnosed with depression by self-rating questionnaires for depression (SRQ-D). Twenty-six patients experienced relief after taking Paroxetine. Fifteen of them were relieved of their vertigo symptoms, 8 were improved, one was not changed, and two were worse. SRQ-D scores were compared between the day of commencement and the day after 4 weeks. Fifteen patients were normalized. Side effects occurred in seven patients; nausea in five and sleepiness in two. The average duration of taking the medicine was 24.4 weeks. Since Paroxetine showed beneficial clinical effects for patients with vertigo, this medicine might be useful for vertiginous patients with depression.
We analyzed 173 emergency patients with acute vertigo who were admitted to the department of otolaryngology, Tokyo Medical University, from January 1999 to December 2003. The hospitalized patients were 4.6% of all vertiginous patients. The most frequent diagnosis was vestibular neuritis, followed by other vestibular lesion, and Meniere's disease. Vertigo with no remarkable finding was 12.1%. We experienced 10 central disorders (5.8%). The 90% of central vertigo was angiopathy. Brain CT was taken in all patients with infarction, but all showed normal images. Brain MRI was mandatory for making diagnosis of brain infarction. High blood pressure was most frequently associated (70.0%) with central vertigo.