Although its pathogeny is still debated, the posterior cervical syndrome of Barré-Liéou is today well defined in the clinic. The illness has grown in importance these last years following the multiplication of cases of traumatic origin (whiplash injury). The vertiginous symptoms are, however, often hard to prove, the vestibular examination being often normal and seldom typical. GREINER et al.  have recently described a very simple method to detect a cervical etiology by giddiness. It consists in investigation of the neck torsion nystagmus. The author has examined 50 cases by this method; in 27 cases there was no torsion nystagmus, 23 times it was clearly established and thus ensured and led to therapeutic treatment. The test seems to be most useful in the daily practice.