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Biomedical subjects

S A Likhachev

Publications and source records attributed to S A Likhachev.

At least 19 recordsLinked to original sources
PubMed2005

[Vestibulo-ocular reflexes in patients with chronic impairment of cerebral circulation].

Vestibular dysfunction was studied in 95 patients with initial cerebral circulatory insufficiency (CCI) stage I and II. Sinusoidal rotation proved highly effective in staging the disease, as initial CCI responses with vestibular hyperreflexia to sinusoidal rotation with closed eyes. With CCI progression, some patients demonstrated inhibition of vestibular excitability while other patients had enhanced excitability. This shows clinical heterogeneity of CCI stage II. P-waves correlating with marked vestibulocerebellar symptoms and high vestibular excitability evidence for CCI stage II. It is established that severity of impairment of nystagmus suppression with glance fixation on a moving object depends on the disease stage.

Brain↗
PubMed2004

[Some characteristics of vertigo in vestibular neuronitis].

The authors present a detailed clinical analysis of objective neurological symptoms and vertigo in patients with vestibular neuronitis. Diagnostic criteria are specified allowing differentiation between vertigo and dizziness, pathognomonic signs of vestibular neuronitis are outlined. Peripheral location of the pathological process in vestibular neuronitis is suggested. How rotating vertigo is forming in patients with vestibular neuronitis is hypothesized.

Adult↗
PubMed2003

[On diagnosis of internuclear ophthalmoplegia].

Optokinetic nystagmus in panoramic mono- and binocular optokinetic stimulation was studied in 24 patients with multiple sclerosis and 20 normal subjects. In control group, asymmetry coefficients and slow phase speed were less than 6% and 7.7% respectively. In the patients, these indices were 7.1 and 14% for binocular optokinetic stimulation and 14.6 and 21.7% for monocular one. Using monocular optokinetic stimulation, electronistagmographic signs of internuclear ophthalmoplegia were detected in all the patients. Therefore, panoramic monocular optokinetic stimulation facilitates determination of joint eye movement disturbances on subclinical level.

Adolescent↗
PubMed2002

[Some characteristics of optokinetic nystagmus in patients with unilateral vestibular neuronitis].

Optokinetic reflex was studied in 20 patients aged 20-58 years with vestibular neuronitis. In 16 decompensated patients the direction of the optokinetic nystagmus was inversed. This inversion disappeared in development of the compensation. Mean values of the amplitude and speed of the slow phase of optokinetic nystagmus are presented for patients with vestibular neuronitis and 20 healthy subjects in mono- and binocular optokinetic stimulation of various intensity.

Adult↗
PubMed2001

[Normal values of optokinetic nystagmus during mono- and binocular panorama stimulation].

Optokinetic nystagmus was studied in 20 normals (14 females and 6 males) aged from 23 up to 35 with the use of mono- and binocular panorama stimulation (a 1.5-m optokinetic cylinder) with the intensity of 0.67, 1.33 and 2 Hz. In normal subjects, the coefficient of OKN amplitude asymmetry was equal to 6% and the coefficient of slow phase velocity was 7.7%. None of the subjects displayed inversion, i.e. change in nystagmus direction for opposite. Temporal nasal asymmetry in adult subjects was not registered either.

Adult↗
PubMed2000

[Vertical vestibuloocular reflexes in unilateral labyrinthine lesions (communication I)].

Vertical vestibuloocular reflexes (VVOR) were studied in 25 patients with unilateral labyrinthine lesions and in 22 healthy subjects. The technique of VVOR is based on stimulation of the internal semicircular canals of the labyrinth by active sagittal head subduction. Dysfunction of the vertical semicircular canals manifested with: VVOR asymmetry with stronger reflexes on the side of the labyrinth affection; predominance of upward VVOR; vertical components of the horizontal vestibuloocular reflexes were not so intensive as VVOR but had the same specific features.

Acute Disease↗
PubMed2000

[Vertical vestibulo-ocular interaction in unilateral labyrinth lesion (communication II)].

Vertical vestibuloocular reflex (VVOR) suppression was studied in 25 patients with unilateral labyrinthine disorders and 22 healthy individuals. The method of the suppression investigation was based on stimulation of the internal semicircular channels of the labyrinth by active sagittal nodding with glance fixation of the object moving with the head. VVOR suppression by glance reflex in patients with unilateral labyrinthine lesion is characterized by reduced reflex suppression effectiveness, especially on the side of the affected labyrinth, via a significant VVOR phase shift down.

Adolescent↗
PubMed2000

[Vertical vestibuloocular reflexes in affection of central parts of vestibular system (communication III)].

Vertical vestibuloocular reflexes (VVOR) were examined in 45 patients with multiple sclerosis. It is proposed to study VVOR basing on stimulation of the vertical semicircular labirynthine canals with active sagittal nodding of the head. Central lesion of the vestibular system is characterized by VVOR hyperreactivity, total failure of VVOR suppression by glance, two types of VVOR domination (typical--up and atypical--down), interocular asymmetry (dissociated nystagmus).

Acoustic Stimulation↗
PubMed1999

[The role of cervical proprioceptive afferentation in compensatory mechanisms of vestibular dysfunction. 1. Passive cervico-ocular reflex in unilateral labyrinthine lesion].

Passive cervicoocular reflex (PCOR) was studied in patients with unilateral affection of the labyrinth at the stage of decompensation and subcompensation according to the following three criteria: nystagmic direction, reactivity coefficient and phasic deviation. In decompensation of unilateral vestibular dysfunction, PCOR presents intensively and asymmetrically while in subcompensation it becomes symmetric and less intensive. The PCOR is characterized as compensatory in unilateral lesion of peripheral vestibular system.

Adult↗
PubMed1999

[The role of cervical proprioceptive afferentation in the mechanisms of vestibular dysfunction compensation. 2. The passive vestibulo-ocular reflex in bilateral labyrinth lesion].

The study was made of passive cervicoocular reflex in patients with bilateral labyrinthine involvement. Passive cervicoocular reflex was assessed by three parameters: direction of the nystagmus, reactivity rate and phasic shift. It is proved that patients with bilateral labyrinthine lesions desplay intensive cervicoocular reflex serving the basic mechanism of vestibular dysfunction compensation in these patients.

Adult↗
PubMed1999

[The study of vertical vestibulo-ocular reflexes].

Methodical approaches for studying the vertical vestibuloocular reflexes (VVOR) have been proposed. Eye movements were recorded by the electronystagmography: vertical movements of each ball of the eye was separately recorded and horizontal movements--in combination. Stimulation of the semicircular canals was performed by active movements of the head in the saggital plane with a frequency of 0.04 Hz (stimulus 1), 0.12 Hz (stimulus 2) and 0.24 Hz (stimulus 3). The VVORs have been recorded with the eyes closed (Program I) and with fixing the visual object on the eyes (Program II). Then, there has been recorded a vertical component of the horizontal vestibulovertical reflexes which evoked by active turn of the head around vertical axis of the body with the eyes closed (Program III) and fixation with the eyes of visual object (Program IV). The elaborated methods enable one to record steadily the VVOR in the all categories of test-subjects. As the VVOR indices there accepted the coefficient of reactivity, phase displacement; coefficients of asymmetry allowing one to compare the intensity of eye movements directed upwards and downwards; to reveal intraocular asymmetry.

Head↗
PubMed1999

[Normal vertical vestibulo-ocular reflexes in man].

The vertical vestibular-ocular reflexes (VVOR) were evaluated in 22 human test subjects aged 18-47 years. The VVOR were evoked by active head movements in the sagittal plane with the frequencies of 0.04 Hz (stimulus 1), 0.12 Hz (stimulus 2), and 0.24 Hz (stimulus 3). Records were made either with eyes closed (Program I) or fixed at an object (Program II). In the norm, the interocular asymmetry was absent and there was an insignificant prevalence of upward VVOR. As was noted, VVOR were largely subdued in the condition of gaze fixation; this was particularly true with the downward vertical vestibular-ocular reflexes.

Adolescent↗
PubMed1999

[Role of cervical proprioceptive afferentation in mechanisms of vestibular dysfunction compensation. 3. Active cervico-ocular reflex in unilateral lesion of labyrinth].

Active cervicoocular reflex (ACOR) was studied in patients with unilateral vestibular dysfunction in decompensation and subcompensation. ACOR was evaluated by coefficient of reactivity, of involvement and phasic shift. ACOR can be used for staging vestibular dysfunction. Decompensation is accompanied by asymmetric ACOR, subcompensation--by symmetric one.

Adolescent↗