Botulinum toxin treatment of acute sixth and third nerve palsy.

Thirty-four patients with acute sixth nerve palsy and nine patients with acute third nerve palsy were treated with botulinum toxin injection to the antagonist, nonparalytic horizontal rectus muscle. In a control group of 52 patients with acute sixth nerve palsy not treated with botulinum in the acute stage, only 16 (31%) recovered spontaneously and did not require surgery. Twenty-two of the 31 surviving patients who could be followed with acute sixth nerve palsy had lateral rectus recovery and surgery was avoided. Four required prisms in their glasses to obtain fusion. Nine patients developed chronic sixth nerve palsy and required surgery. In this group of acute sixth nerve palsy patients, eleven were bilateral. Seven of these eleven developed chronic sixth nerve paralysis, and required strabismus surgery. This suggests the prognosis for recovery following botulinum treatment in cases of acute bilateral sixth nerve palsy is not as good as in the unilateral cases. Botulinum toxin treatment does not appear to be effective in chronic sixth nerve palsy, as judged by results of treatment in one patient known to have a chronic palsy. Nine of nine patients with acute third nerve palsy had medial rectus recovery with fusion horizontally in primary gaze. None have required surgery. Only four of nine showed improvement in vertical rotations. The remaining five patients avoid vertical diplopia by a compensatory chin position. Botulinum toxin treatment of patients with acute sixth and third nerve palsy appears beneficial. However, since some in this group of patients may recover spontaneously, a randomized, double-blind study may be necessary to more definitively determine the effectiveness of this therapy.