Incidence, risk factors and clinical features of myasthenic crises

Abstract

OBJECTIVE: To determine the clinical features and outcomes of Hong Kong Chinese generalized MG patients, with focus on independent risk factors that predict development of MG crises and poor clinical outcome. BACKGROUND: Autoimmune myasthenia gravis is an important neurological disorder as it affects patients of all ages, causes mortality and significant morbidity, and yet it is treatable. It is crucial to diagnose and treat generalised myasthenia gravis early to prevent myasthenic crisis which is a fatal neurological emergency. DESIGN/METHODS: Generalised MG patients who presented to Queen Mary Hospital neurology clinic from 1994-2013 were retrospectively studied. Demographics, clinical features including age of onset, disease severity, duration of ICU care, use of ventilator support, presence of thymoma and history of thymectomy, use of different immunosuppressive therapies and comorbidity index will be analyzed by multivariate analysis for factors that independently predict development of MG crises. Subgroup analysis of generalised MG patients with crises will be performed to study for any independent factors predicting mortality and poor clinical outcome. RESULTS: 118 patients with generalised MG were included. 83 (71.6%) were female and mean age of onset was 44.8 years. 44 (37.9%) of them had thymoma. 87 (75%) had received immunosuppressive treatment at some point of their disease courses. 34 patients (29.3%) had at least 1 myasthenic crisis, giving a total of 63 episodes of crisis. None of these resulted in mortality. CONCLUSIONS: Our population had a high incidence of thymoma but it did not appear to be an independent risk factor of development of crisis. On the other hand, older age at onset and history of immunosuppression therapy would decrease risk of crisis. With the high utilization rate of immunoglobulin or plasmapheresis therapy, there is no mortality in these episodes.