Biomedical subjects

S Stoyanoff

Publications and source records attributed to S Stoyanoff.

4 recordsLinked to original sources

PubMed1989

On the search for markers of poor vestibular compensation.

The effectiveness of pursuit gain, cancellation of the vestibulo-ocular reflex, and a clinical oscillopsia test were assessed as vestibular function tests and tests that may allow prediction of which patients would compensate poorly after vestibular surgery. Cancellation of the vestibulo-ocular reflex in 17 patients and 17 control subjects was compared. Pursuit gain for 17 patients was determined for three frequencies at peak velocities of 25 and 50 degrees/sec. The oscillopsia test was administered to seven patients during at least the first 6 postoperative months. We are unable to state that any of these parameters were effective "markers" of impaired compensation, but the oscillopsia test appears to be a useful clinical tool for vestibular examination.

Ear, Inner↗

PubMed1989

Bilateral vestibular loss and oscillopsia.

The electronystagmographic (ENG) records of 5,499 patients were reviewed so as to note the level of caloric activity. Bilateral caloric reduction or loss was found in only 1.6%. Although no diagnosis could be made with a high degree of confidence in the majority of patients, bilateral Ménière's disease and exposure to ototoxic drugs were identified most frequently. The degree of caloric reduction or loss did not correlate with the subjective symptom of oscillopsia, oscillopsia test findings or results of low frequency harmonic sinusoidal rotation tests. In a few patients with bilateral caloric loss, no oscillopsia was demonstrated. Many mechanisms other than the vestibulo-ocular reflex exist to provide visual stability, and we assume these become effective in some patients with bilateral caloric reduction or loss.

Adult↗

PubMed1986

Vertical nystagmus in routine caloric testing.

Vertical nystagmus may occur in caloric testing when only horizontal is expected. We examined this occurrence in 112 normal subjects and in 339 patients with dizziness. Vertical nystagmus was found in 29 percent of normals and in 12 percent of patients with dizziness, more often with hot than cool caloric stimuli and it is always accompanied by horizontal nystagmus. The finding occurred with peripheral and central nervous system diagnoses as well as with patients whose dizziness was considered psychogenic or was undiagnosed. Maximum slow component velocity (SCV) of vertical nystagmus was usually half or less than that of the nystagmus in the horizontal lead. The SCV time profiles of the nystagmus in horizontal and vertical leads differed considerably. Possible origins of vertical nystagmus are discussed. Whatever the origin, it is clear that the finding of vertical nystagmus in routine caloric testing does not automatically denote disease of the central nervous system.

Adolescent↗

PubMed1984

Head and eye movements in congenital nystagmus.

Patients with congenital nystagmus exhibit a wide range of unusual nystagmus waveforms and strategies to obtain maximum visual acuity. We investigated target acquisition strategies, head-eye coordination, and the effects of alteration of head position relative to gravity on congenital nystagmus waveforms in five patients. No changes in the nystagmus were found when patients' heads were placed in different positions relative to gravity. Two patients had distinctive abnormalities of head-eye coordination characterized both by failure of eye movement to precede head movement and by position of the eye in the orbit, after target acquisition, being in a direction opposite that of the head movement. We conclude that static changes in head position relative to gravity probably do not influence congenital nystagmus waveforms. In addition, some patients with congenital nystagmus may have abnormal head-eye coordination.

Adult↗