[Molecular genetic diagnosis and clinical features of hereditary neuropathy with liability to pressure palsies in Belarusian patients].

OBJECTIVE: To analyze the molecular defect, a phenotype of hereditary neuropathy with liability to pressure palsies (HNPP, OMIM 162500), in patients with PMP22 gene mutation caused by 1.5 Mb deletion at 17p11.2. and present the principles of diagnosis and genetic counselling. MATERIAL AND METHODS: Patients were selected on the basis of the results of the clinical/genealogical analysis, neurological examination and ENMG study. Genomic DNA was isolated from peripheral blood leukocytes. RESULTS AND CONCLUSION: DNA diagnosis was performed in 5 families (the PMP22 deletion was found in 9 patients). The authors described clinical and electrophysiological characteristics and presented a diagnostic protocol. Identification of the mutation makes it possible to confirm the clinical diagnosis, assess genetic risks for the outcome and perform a prenatal DNA diagnosis in HNPP families.

[The influence of otolithic afferentation on the vestibulo-ocular interaction in the patients presenting with an unilateral lesion in a peripheral vestibular neuron].

The objective of the present work was to study the influence of otolithic afferentation on the vestibulo-ocular interaction in 20 patients with vestibular neuronitis (at the stages of decompensation and subcompensation) and in 30 healthy subjects by the electronystagmographic technique. The sinusoidal (program 1) and eccentric (program 2) rotation was applied with the angular velocity of 10 degrees/s (stimulus 1, rotation rate 0.04 Hz), 30 degrees/s (stimulus II, rotation rate 0.12 Hz), 60 degrees/s (stimulus III) and oscillation periods of 18, 6, and 3 s respectively. No significant changes in the parameters of the vesicular reflex were observed in the patients with vestibular neuronitis and control subjects studied in the phase of decompensation under programs 1 and 2 . The study of the patients presenting with vestibular neuronitis in the subcompensation phase (program 2) revealed a significant increase of nystagmus intensity on the affected side compared with the respective parameters estimated in the framework of program 1 (p<0.001). The enhancement of stimulation did not result in any significant changes in the character of vestibuloocular interactions. The results of the study indicate that otolithic afferentation influences the process of compensation of peripheral vestibular labyrinth dysfunction in the patients presenting with vestibular neuronitis at the stage of decompensation.

[Modern diagnostics of vestibular dysfunction].

Based on the data of anatomy and physiology of vestibular apparatus, authors reviewed methods of assessment of its functional state, theoretical and practical aspects of their strength and limitations. A special attention is drawn to current approaches to investigation of vestibular-ocular reflex (VOR) in different pathologies. The authors emphasized that the diagnostics of vestibular dysfunction should be based on a battery of tests. Both traditional and new methodologies should be used.

[Gaze-evoked suppression of the vestibular-ocular reflex in patients with posterior cervical sympathetic syndrome].

This vestibulometric (sinusoidal rotation) study included patients with posterior cervical sympathetic syndrome (n=40) and with vestibular neuronitis (n=20) as well as 20 healthy subjects of the control group. Vestibular dysfunction was induced by the method proposed by de Klein. The patients with posterior cervical sympathetic syndrome in the decompensation phase displayed abnormal gaze-evoked suppression of the vestibular-ocular reflex when their head movements lined up with sinusoidal rotation. This symptom is considered to be of primary value for the diagnosis of vestibular dysfunction in these patients.