Convergence substitution in pontine tegmental hemorrhage: an observation with Frenzel goggles

We report a case in which convergence movement was substituted for bilateral horizontal gaze palsy due to a pontine tegmental hemorrhage. When visual fixation was suppressed with Frenzel goggles (FG), substituted convergence movements were prominent in our patient. The observation suggests that both vergence eye movements and horizontal gaze movements act synergistically and lesioning of the version system results in overactivity of the convergence system after a pontine hemorrhage. Furthermore, it may be worth using FG in the observation of substituted eye movements in patients with horizontal gaze palsy due to a pontine tegmental injury.