Botulinum-A toxin for ocular muscle disorders

Treatment of unilateral acute sixth-nerve palsy with botulinum toxin

We studied 29 consecutive patients with acute unilateral sixth-nerve palsy, who received botulinum toxin injection to the antagonist medial rectus muscle. The average interval between onset of palsy and treatment was 40 days and the mean follow-up from the last injection was 14 months. Before treatment, esotropia in the primary position ranged from 12 to 45 prism diopters and limitation to abduction in the affected eye ranged from -2 (approximately 15 degrees lateral to midline) to -6 (15 degrees nasal to midline). After treatment, 22 of 29 patients (76%) had complete recovery of motility as determined by version testing. Of the seven patients with a residual abduction deficit, two had fusion in the primary position, three had fusion with prismatic correction, and two patients required subsequent surgery. Botulinum toxin injection seems to be an effective treatment option in cases of acute unilateral sixth-nerve palsy.

Early botulinum toxin treatment of acute sixth nerve palsy

Eight patients with total sixth nerve palsy were treated with botulinum toxin injection to the antagonist non-paretic medical rectus, within eight weeks of the onset of the palsy. Within a few days seven of the eight gained fusion without the necessity of a marked head turn, and none complained of confusing reversal of diplopia. The same seven recovered full function. The mean follow-up period after the last injection was 20 months. Seven palsies were the result of head trauma and one was due to cerebro-vascular disease. This preliminary report suggests that early botulinum toxin injection of patients with recent onset sixth nerve palsy is beneficial. Although all of the patients may possibly have recovered full lateral rectus function without treatment, the aetiologies of their palsies were of the type that frequently do no resolve. A randomised double-blind study is necessary more precisely to determine the effectiveness of this form of therapy.

Early and late botulinum toxin treatment of acute sixth nerve palsy

Ten patients with sixth nerve palsy were treated with botulinum toxin injection to the antagonist nonparetic medial rectus. All patients were followed for a minimum of 14 months after the last injection. Six patients were treated within eight weeks of the onset of the palsy. Within a few days five of the six gained fusion, without the necessity of a marked head turn and none complained of confusing reversal of diplopia. The same five recovered full function. Four patients with no medial rectus contracture on forced duction testing were treated six months or longer after the onset of the palsy and none recovered full function. One of the four patients was permanently over-corrected despite persistent weakness of the lateral rectus. This preliminary report suggests that early botulinum toxin injection of patients with recent onset (acute) sixth nerve palsy is beneficial. Since some patients may recover spontaneously a randomised double-blind study is necessary to more precisely determine the effectiveness of this form of therapy. Botulinum toxin does not appear to be effective in facilitating recovery in those cases with poor lateral rectus function six months or longer after the onset of the palsy, even when there is no contracture of the medial rectus.

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.