[Benign paroxysmal positional vertigo and provocative maneuvers].
Main features of the benign paroxysmal positional vertigo (B.P.P.V.) are: latency before the onset of vertigo, nystagmus of the rotatory type beating toward the lower ear, nystagmus tires out, nystagmus gets inverted when the head is brought back to orthostatism, nystagmus is reproducible as many times as the position is taken. B.P.P.V. is due to a deposit of heavy material on the cupula of the posterior semi circular canal. In this unusual condition, the cupula moves under the effect of gravity acceleration. The goal of the treatment is to free the cupula. The manoeuvre consists after determination of the position that elicits the vertigo to move the whole head and body together of the patient to a 180 degree opposite position in which the addition to the endolymph flow forces and weight forces of the material will unstick it from the cupula. The positive result of the manoeuvre is instantly proved by the arising of a rotatory nystagmus beating again toward the sick ear. In other words it is not the inversion of the primary nystagmus but a nystagmus beating the same direction. This is explained by the dynamic of the cupula: in the prime position the density modified cupula moves toward the canal. At the end of the manoeuvre when the velocity of the head is zero, the cupula has to support different forces. First the addition of the endolymph flow forces and the inertia of the heavy material makes the cupula move toward the ampulla. Secondly when the superficial tension forces are too high the heavy material unstick from the cupula and it goes back to its normal position. En this very moment the cupula moves toward the canal. The results are of more than 90% positive in one ore two sessions 4,2% of recurrence. The manoeuvre is unsuccessful in spontaneous nystagmus revealed by a position, in torsional nystagmus as in fistulas or in central position nystagmus.