Benign positional paroxysmal vertigo: videonystagmographic study using rotatory test.
Benign Peripheral Paroxysmal Vertigo is a disease of the posterior labyrinth caused by endolymphatic debris, provoking vertigo with some movements of the head. Diagnosis is usually made by finding the positional nystagmus with appropriate manoeuvres. Spontaneous resolution is frequent and in these cases diagnosis is only probable and suspected from anamnesis. Aim of the present investigation was to establish more evaluation parameters in the study of Benign Peripheral Paroxysmal Vertigo. A series of 97 selected patients presenting Benign Peripheral Paroxysmal Vertigo, have been submitted to sinusoidal kinetic test. Patients have been studied during the acute phase of the condition and after recovery. Vestibulo-oculomotor reflex has been sought by stimulating the horizontal and vertical canals. Kinetic stimulus consisted in sinusoidal rotation at 0.12 Hz and 0.05 Hz. Evaluation parameters comprised preponderance, gain and phase of provoked nystagmus, recorded by means of an Ulmer videonystagmograph. Using this same technique of stimulation, 20 normal volunteers were studied in order to establish normal values for reference. Values obtained in the patient population of patients have been compared, by Student t test, with values obtained in the same cured patients and with those in normal subjects. In the patients with Benign Peripheral Paroxysmal Vertigo of the lateral canal a nystagmus preponderance toward the healthy side was observed, as well as an increase in the phase lead, also in the canals not affected by the condition. In cured patients, disappearance of the preponderance and persistence of the phase abnormalities are observed. These results suggest a multicanal pathogenesis of Benign Peripheral Paroxysmal Vertigo.