Bechterew's phenomenon in humans. A new explanation.

Bechterew's phenomenon, or reversal of post-unilateral labyrinthectomy spontaneous nystagmus following subsequent contralateral labyrinthectomy in experimental animals, has been known for 100 years. However, it is rarely observed in humans. This paper describes Bechterew's phenomenon in a patient following successful mitral valve replacement and aorto-coronary bypass. The observations are compatible with a recent study which postulates that intervestibular commissural pathways, forming closed loops for neural signals between the vestibular nuclei, may be the main site for vestibular compensation which is associated with the recovery of balanced resting activity in the bilateral vestibular nuclei (Galiana 'et al., 1983). Using simple analytic arguments, it is found that compensation of nystagmus following unilateral labyrinthectomy, the Bechterew's phenomenon and its compensation, and recovery nystagmus could all result from long-term neural changes at the level of commissural connections.