Convergence and divergence synkinesis: A recovery pattern in benign pontine hematoma

Abstract

Two patients with ‘benign’ hematoma of the tegmentum pontis showed complex oculomotor abnormalities associated with involuntary vergence movements induced by voluntary horizontal or vertical conjugate gaze attempts. In the first case, we found clinical evidence for unilateral destruction of the paramedian pontine reticular formation (PPRF) and abducens nucleus, and isolated dysfunction of the PPRF (initially bilaterally, then unilaterally) was suggested in the second case. These induced converging and diverging movements should be differentiated from convergence/divergence nystagmus, spasm of the near reflex, and pretectal esotropia. They are not voluntary substitution movements and probably correspond to central synkinetic phenomena, which may occur when pontine centers of gaze are involved, together with sparing of brainstem association pathways.

Key Words:

• ophthalmoplegia
• convergence
• divergence
• pontine hematoma
• synkinesis