Stability Of Botulinum Toxin A Dosage Over Time In Patients With Hemifacial Spasm, Blepharospasm And Cervical Dystonia/Torticollis. (P7.068)

BACKGROUND: Botulinum toxin A(BTA) has been considered an effective treatment for hemifacial spasm(HFS), blepharospasm and cervical dystonia(CD). Systemic drugs have not been shown to be beneficial in HFS, however, BTA has been considered a safe and effective long term treatment. For blepharospasm, 90% patients demonstrated clinical improvement after BTA injections. With CD, excellent outcome has been reported with 76% of patients not returning for further BTA treatment after initial consultation. Studies have shown that sustained treatment efficacy required higher doses but correlation with number of injections has never been studied. OBJECTIVE: To determine stability of BTA dosage and amount of injections in patients with HFS, blepharospasm, and CD. METHODS: Single center retrospective study. A review of electronic medical records was performed for patients who underwent repeat BTA injections for HFS, blepharospasm, and CD from July through September 2013. Documentation was reviewed for (1) number of treatments and (2) changes in doses, which was determined by comparing at least two doses of BTA from initial evaluations to most recent. RESULTS: Fifty-four patients were included, 13 males and 41 females. Forty-five patients were Caucasian, 8 African American, and 1 Asian. Fifteen out of 21 patients with HFS, 11/15 with blepharospasm and 16/23 with CD required a change in BTA dosage over multiple treatments. HFS patients with > 10 BTA injections correlated with a change of 2.5 units or more of BTA, X2=4.20 (p<0.05). Blepharospasm patients with > 10 BTA injections will most likely require a change in BTA dose of 5 units or more, X2=3.64 (p>0.05 and p<0.10). There was no association between the number of BTA injections received and change in BTA dosage for patients with CD, X2=0.18 (p>0.05). CONCLUSIONS: Patients with HFS and blepharospasm who have undergone more than 10 BTA injections will most likely require a change in their dosage over time. There was no correlation between number of BTA injections and change in dosage in CD patients.