Proposed criteria for the O'Sullivan McLeod syndrome: Case series and literature review

Abstract We aimed to summarize the clinical characteristics of the O'Sullivan McLeod syndrome and propose the diagnostic criteria of the syndrome. We reviewed our database to identify patients with the O'Sullivan McLeod syndrome. Online databases including PubMed, EMBASE, and OVID were also searched for relevant cases. We identified a total of 24 cases, including 3 cases from our database and 21 ones from online searching. A predominance of male was observed [17 (73.9%)] with median onset age of 31 (range: 15–56) years old. The median (range) disease duration was 9 (0.5–28) years at the time of the visit. All patients showed involvement of hands and ~1/3 patients reported weakness and atrophy of right/left forearm. The upper arm was scarcely affected (8.7%). Needle electromyography suggested chronic denervation in C7‐T1 among the majority of involved cases (over 78%). Cervical magnetic resonance imaging showed longitudinal T 2‐hypertenssive signals among 5/14 (35.7%) patients, which confined to the anterior horn area. No patients showed responsiveness to immunotherapy. Ten patients remained clinical stable during follow‐up, nine ones manifested chronic progressive course. The O'Sullivan and McLeod syndrome, characterized by progressive weakness and atrophy in upper limbs, might be an incurable disorder of lower motor neuron. Onset in early adulthood, the plateau period of over 12 months and years of chronic progression in clinical manifestations might be supportive indicators for the diagnosis of the syndrome. The prognosis is relatively good with no effective treatment.