[Myasthenia gravis in the elderly: diagnosis, comorbidity and course: 45 cases]

Analyze the clinical presentation, laboratory indicators, and outcome of patients with late-onset myasthenia gravis (after 60 years).

This retrospective cohort design with prospective follow-up included 45 patients with late-onset myasthenia gravis diagnosed in hospitals in Avignon, Montpellier, and Nimes between 1993 and 2000. Prospective data collection of their subsequent course took place in 2001.

Median age at onset was 72 years and median follow-up 35.5 months. Initial symptoms were ocular (38/45, 95%) and bulbar (31/45, 69%). Initial Osserman grades were distributed as follows: 10 grade I, 2 grade IIA, 25 grade IIB, 8 grade III and no grade IV. Anticholinesterase antibodies were positive in 39 patients (91%), response to anticholinesterase positive in 31/33 (94%), and electrophysiological abnormalities observed in 20/33 (61%). Thoracic computed tomography, performed in 42 patients (93%), found thymic abnormalities in 7. At least one comorbid disease was diagnosed in 41/43 patients (93%) and an autoimmune disorder in 18/43 (42%). In all, 42 patients (93%) received anticholinesterase and 36 (80%) immunosuppressive therapy. Sixteen patients (36%) died during follow-up, 8 of causes directly related to the myasthenia gravis. The relative risk of death estimated by odds ratios (OR) was highest for patients with comorbid cancer (OR 8.6 [1.8-40.6]) and those with the highest Osserman scores: grades I-II OR: 0.05 [0.01-0.29] versus grades III-IV OR: 15.5 [2.9-83.0].

Late-onset myasthenia gravis is specific in many aspects (presentation, autoimmune and other comorbid conditions, and course) that require attentive care.