Biomedical subjects

J M Furman

Publications and source records attributed to J M Furman.

93 records · Page 6Linked to original sources

PubMedDate not supplied

Visual-vestibular interaction during off-vertical axis rotation.

The aim of this study was to further define the eye movement response to combined visual and vestibular stimulation, especially during linear acceleration. Subjects included 15 asymptomatic healthy individuals (8 females and 7 males) between the ages of 20 and 31 years. Vestibular stimulation consisted of earth-vertical axis rotation and off-vertical axis rotation (OVAR). Visual stimuli consisted of projected vertical stripes that were rotated for optokinetic trials and stationary for visual augmentation trials. A small laser target (0.5 mW, 0.5 degree arc) that rotated with the subject was used for fixation trials. Eye movements were measured with electro-oculography. Results showed that visual-vestibular interaction during sinusoidal rotation was not affected by a 15 degree off-vertical tilt. Constant velocity OVAR induced a continuous nystagmus whose slow component velocity contained a nonzero baseline, that is, a bias, and a periodic fluctuation at the rotation frequency, that is, a modulation component. The modulation component during visual fixation was reduced as compared with that seen during rotation in the dark, but was not absent. Constant velocity OVAR in the presence of earth-fixed stripes induced a consistent sinusoidal modulation. Our results suggest that visual-vestibular interaction for otolith stimulation differs from visual-vestibular interaction for semicircular canal stimulation. The modulation component of the response to OVAR appears to be modified by visual stimulation to a lesser extent than other vestibular-induced eye movements and thus may reflect a more "direct" vestibulo-ocular response. The bias component of the response to OVAR can be substantially influenced by vision and thus may depend upon more "indirect" pathways.

Acceleration↗

PubMedDate not supplied

Functional reach and single leg stance in patients with peripheral vestibular disorders.

The purpose of this study was to compare functional reach distance and right single leg stance time in patients who had peripheral vestibular disease. Twenty-eight patients (15 female, 13 male) between the ages of 35 and 84 were asked to perform 3 trials each of functional reach (FR) and right single leg stance (SLS). SLS times were measured by a Kistler static force platform on line with a Caspar personal computer. FR distance was measured by using a free-standing 147-cm rule. In addition, each subject filled out the Dizziness Handicap Inventory (DHI). Trials were randomized to prevent fatigue or practice effects. A Pearson product-moment correlation was performed between FR and SLS (r = 0.59, P = 0.001). Post hoc analyses of the first, the best, and the average scores highlighted the importance of using means for comparison in a population as variable as the vestibularly impaired. Post hoc analyses showed no correlation between the DHI score and either functional reach distance or single leg stance time. However, when the subjects were divided into groups based on DHI score (group 1 with DHI < or = 49/100, group 2 with DHI > or = 50/100) and a pooled two-sample t-test was performed, a significant difference (P = 0.05) was found in functional reach distance; the subjects who reported less perception of handicap reached farther than those who reported more perception of handicap. No difference was found between the two DHI groups in single leg stance time. Post hoc correlations of functional reach and single leg stance time. Post hoc correlations of functional reach and single leg stance within the two DHI groups showed a higher correlation in group 1 (DHI < or = 49/100), with r equals 0.65 (P < or = 0.01), than in group 2 (DHI > or = 50/100), with r equals 0.38 (P = 0.20). The study found a highly significant, moderate correlation between functional reach distance and single leg stance times in patients with peripheral vestibular disease. These results support the use of FR as an additional assessment tool with patients who have peripheral vestibular disease.

Adult↗

PubMedDate not supplied

Clinical evidence that the vestibular system participates in autonomic control.

The vestibular system, including both the peripheral vestibular system, that is, the labyrinth, and the central vestibular system, is known to influence autonomic function in several ways that have clinical implications. This paper discusses evidence for vestibular influences on autonomic control from normal human subjects, evidence for vestibular influences on autonomic control from patients, clinical implications of vestibulo-autonomic regulation, and speculations regarding possible clinical implications of vestibulo-autonomic control. Situations that provoke vestibular-induced autonomic responses in normal subjects include vestibular laboratory testing, vehicular motion, simulators, and, possibly, exposure to microgravity. Patients with peripheral and central vestibular abnormalities manifest both symptoms and signs of autonomic dysfunction presumably via vestibulo-autonomic connections. Vestibulo-autonomic regulation impacts vestibular diagnostic testing, clinical diagnosis of balance disorders, and treatment of balance disorders. In addition to well-recognized peripheral and central vestibular disorders, anxiety disorders have recently been linked to vestibular dysfunction in a subset of patients. In particular, vestibular dysfunction has been linked to panic disorder and agoraphobia. Vestibular-autonomic connections may form a basis for an association between vestibular dysfunction and panic attacks. The importance of vestibulo-autonomic regulation in the clinical arena is not fully known. Two speculative areas discussed in this paper include vestibular-induced orthostatic intolerance and the role of vestibular-respiratory pathways on sleep apnea.

Autonomic Nervous System↗