Inpatient administration of complement inhibitors as rapid-acting therapy for recurrent or refractory myasthenic exacerbation: A case series, review of the literature, and discussion of pathophysiology.
Greenberg Julia J, Seyam Muhannad M, Muppidi Srikanth S
Complement inhibitors are primarily used for symptomatic/refractory but stable myasthenic patients in the outpatient setting, however there is emerging data to suggest that complement inhibitors may be an effective rescue therapy in acute myasthenic exacerbation or crisis. We present two cases of non-ventilator-dependent patients with refractory or recurrent myasthenic exacerbation in whom eculizumab was used as a rescue therapy, review the literature to date on inpatient use of complement inhibitor therapy for myasthenic crisis/exacerbation, and discuss the pathophysiology underlying rapid clinical response. Both patients had a rapid response to eculizumab with return of ability to speak and swallow within 48 h in one patient and reduction in MG-ADL score of >6 points within 2 weeks in one patient. Both achieved minimal symptom expression (defined as MG-ADL score of 0 or 1) within weeks and had sustained response to outpatient complement inhibitor therapy. Nineteen previously published papers (58 patients) were identified. Many patients had a clinically significant reduction in MG-ADL score or other objective evidence of clinical improvement within days, and had a sustained benefit with continued outpatient therapy. Our findings add to a growing body of literature suggesting that complement inhibition may be a useful, fast-acting therapy for myasthenic exacerbation in the inpatient setting in some cases. This rapid response is likely due to functional complement blockade in patients with complement mediated neuromuscular junction damage as a primary cause of MG exacerbation/crisis.