Unusual presentation of Lewis-Sumner Syndrome in elderly

Lewis-Sumner Syndrome (LSS) is a rare disease that affect usually young adult. It is characterized by a proximal and especially distal myalgia, asymmetric muscle weakness, which mostly affects the upper limbs with early onset. Diagnosis can be difficult to establish if the clinical presentation is atypical. We report here a rare case of LSS in an old patient with unusual clinical aspects. A 70-year-old female patient with a history of atrial fibrillation complicated by pulmonary embolism, presented with myalgia and muscle weakness of the shoulders, upper arms, hips and thighs. This involvement was bilateral, symmetrical and evolving for 3 months, causing difficulties in climbing stairs, standing or walking. Physical examination showed a proximal muscle deficiency affecting proximal muscles of the upper and lower limbs. In this stage, we suspected an inflammatory myopathy or polymyalgia rheumatica. Biological investigation showed an inflammatory syndrome and an elevated lactate dehydrogenase level. The immunoblot polymyositis profile was negative. Magnetic Resonance Imaging (MRI) of hips revealed a signal abnormality in the gluteus medius muscles on both sides with inflammatory appearance. The Electromyography revealed sensorimotor neuropathy affecting the four limbs more pronounced in lower ones, with motor nerve conduction blocks. The cerebrospinal fluid study revealed a proteinorachia at 0.4g/l with normal glycorachia and normal cell counts. These results confirmed the diagnosis of LSS. The patient was treated by corticosteroids at dose of 1 mg/ kg/ day during 2 months, with a progressive decrease of treatment. The evolution was marked by spectacular clinical and biological relief.