Abstract
We present here a case showing paradoxical convergence during lateral gaze. A 61-year-old female complained of dizziness when she saw horaizontally moving objects. She had a 20-year history of diabetes with retinopathy, nephropathy, and neuropathy.
In an attempted leftward gaze, both eyes were transiently convergent for several seconds, disturbing ocular abduction. This paradoxical eye movement sometimes occurred in an attempted rightward gaze, and was accompanied with pupilary miosis. When one eye was covered, the other eye showed no disturbance in lateral gaze. Caloric vestibular stimulation induced conjugate eye movement in both directions. MRI did not show any lesion in her brain. These findings indicated that the gaze palsy in this case was due to covergent spasm (i.e., spasm of the near reflex). The convergent spasm appearing in attempted lateral gaze was successfully treated with baclofen, an agonist of GABA-B receptor. Its pathophysiology is unclear, but we supposed an increased excitability in the supra-oculomotor parts of the vergent eye movement system. A neural command to generate horizontal saccade simultaneously enters the vergent system, which may trigger the convergent spasm of this case.
