The use of botulinum toxin in acquired nystagmus: literature review and case presentation

Abstract

Aim: To review the literature on the use of botulinum toxin (BT) in the treatment of symptoms associated with acquired nystagmus and to present a case report of a patient who experienced relief of symptoms with an injection of only one horizontal rectus muscle. Method: A literature-based review on the use of BT in acquired nystagmus. A case is presented of a 40-year-old woman with multiple sclerosis who had BT injection to relieve symptoms of reduced vision and oscillopsia due to horizontal nystagmus. Orthoptic findings before and after the injection are documen­ted and the management of the case described. Results: It has been reported that BT can be injected into both the horizontal recti of one eye, or the retrobulbar space of one eye, to alleviate the symptoms of oscillopsia associated with acquired nystagmus. Numerous detrimental side-effects asso­ciated with the injections have been reported. In the case presented the patient reported an improvement in vision and oscillopsia following a BT injection into the left lateral rectus muscle. This was substantiated by an objective improvement in the visual acuity, with few side-effects. Conclusion: BT injections into selected extra-ocular muscles can temporarily reduce the amplitude of nystagmus and relieve the symptom of oscillopsia. The case presented shows that a subjective Improve­ment in symptoms can be achieved by a BT injection in only one horizontal rectus muscle