Periorbital injections of botulinum toxin a: a novel therapeutic option for convergence spasm in neuropsychiatric disorders

Abstract

Abstract Purpose Convergence spasm (CS, spasm of near reflex) is characterized by transient attacks of convergence, miosis and accommodation, often associated with functional neurological disorders. To date, no simple and efficient treatment option is available for CS. This study investigates whether periorbital botulinum toxin injections as used in essential blepharospasm are also a treatment option in these patients. Methods All patients with convergence spasm having been treated with periorbital BoNTA injections in the department of neuro-ophthalmology were identified. Data were extracted from patient files concerning details and subjective effectiveness of botulinum toxin injections and relation to psychiatric or neurological disorders. Patients reporting with a history of closed-head trauma or organic neurologic pathologies possibly causing CS were excluded. A telephone assessment with a standardized questionnaire was performed to evaluate mental health issues as a trigger, as well as the long-term effect and satisfaction with periorbital injections. Results Of 16 patients treated with periorbital botulinum toxin injections for convergence spasm, 9 patients reported depression and/or anxiety disorders ongoing or in the past. A median number of 3 injections (range 1–13) was administered with a variable effect (relief of symptoms) between no effect and effect of up to more than 12 weeks. A longitudinal follow-up revealed ongoing symptoms in five patients. Conclusions Periorbital botulinum toxin injections are less invasive than injections in the medial rectus muscle and can be a bridging therapeutic option in patients with CS. Mental health exploration is important due to psychiatric comorbidity.