Background: Onabotulinum toxin A (OnA) is a well-tolerated and effective treatment for chronic migraine (CM). However, based on research indications that incobotulinum toxin A (InA) would be equally effective, a Veterans’ Health Administration Medical Center mandated a 2-year trial of InA as more cost-effective alternative to OnA. Although InA is used for many similar indications as OnA, it is not Food and Drug Administration approved for treating CM, and complications occurred in several patients with CM following this treatment change. We conducted this retrospective analysis to evaluate differences in the efficacy of OnA and InA and identify the reasons for the adverse effects of InA in some of these patients. Methods: We performed a retrospective review of 42 patients who had been effectively treated with OnA and were then switched to InA. The differences between treatment responses to OnA and InA were assessed through the evaluation of pain on injection, number of headache days, and duration of action. Patients received injections at 10- to 13-week intervals. Those who reported excessive pain on injection of InA were switched back to OnA. Findings: Severe burning pain on injection was reported by 16 (38%) patients for InA only and by 1 (2%) patient for both InA and OnA. Neither migraine suppression nor the duration of effect was significantly different between OnA and InA. Conclusions: Reformulation of InA with a pH-buffered solution may eliminate the difference in pain on injection. InA would then be a good alternative to OnA for treating CM.

Increased susceptibility to opportunistic infections (OI) in multiple sclerosis (MS) patients is a real concern amongst neurologists when using disease-modifying therapies (DMTs). DMTs used in modulating or suppressing the immune system for MS management may risk the patient with lymphocytopenia, raising the possibility of OI; however, this lymphopenia may contemplate as a biomarker for drug response, degree of immunomodulation, and drug compliance. The OI could be reactivation of varicella-zoster, progressive multifocal leukoencephalopathy (PML) induced by John Cunningham virus (JC virus), Pneumocystis jirovecii infection, cryptococcal meningitis, atypical mycobacteria, and many more.We present a non-immunized case of varicella-zoster reactivation with dimethyl fumarate (DMF) therapy. Surprisingly, the patient's lymphocyte count trend during her previous follow-up visits remained in the range of normal to grade 1 lymphopenia but with her current flared-up rash presentation, she had a profoundly low CD8+ and CD4+ cell counts (CD8+ cell count << CD4+ cell counts) despite an absolute lymphocyte (ALC) level far above 500 cells/µl; in fact, it was 13.6% higher when compared to her last quarterly levels. Controlled trials with DMF claimed no serious infection even with a lymphopenia range of 500-800 cells/µl, which is untrue in real clinics and it would be wise and reasonable to follow the lymphocyte subsets along with ALC to prevent potential opportunistic infections.Recently, comprehensive strategies were evolved to mitigate OI risk for MS patients while on DMTs. These were not only limited to lymphocyte threshold monitoring but extended to address features in terms of screening recommendation, vaccination advice, the need for antibiotic prophylaxis, neuroimaging, laboratory checkups, medication dosing, and behavioral modifications. Our patient was not immunized with zoster vaccine and, unfortunately, DMF has no proper structured guidelines regarding vaccination against OI prevention as other few DMTs have. Our case could suggest that MS patients need proper vaccination guidelines from the Centers for Disease Control and Prevention (CDC) before starting DMF.