Congenital cleft in the pontomedullary junction.

A 4-month-old boy is reported with complete absence of horizontal gaze. Magnetic resonance imaging revealed a congenital cleft at the pontomedullary junction directed from the right anterior paramedian region toward the posterior midline, sparing the posterior region of the pontine tegmentum and the medulla oblongata. Such clefts are extremely rare, and there is only 1 previous report in the literature.