The head shaking nystagmus.

The head shaking nystagmus is a sign of vestibular assymmetry. Its detection is simple office test useful for screening the patients with vertigo and dysequilibrium. Its nature defies its recording with electro-oculography and is simply observed under Frenzel's glasses. The direction of nystagmus is persistently directed away from the site of lesion and is not influenced by the compensatory adjustments. It is transient, rotatory and repeatable in nature. Its reliability is limited in face of the difficulty in its recognition. In presence of strong spontaneous nystagmus in the same face, it is not recognised easily. In the present study, its validity in peripheral disorders was 49.27% and 14% in central cases. There are limitations In earring out this test in situations of railed intracranial the tension, hence, its use in the latter cases is limited.