WOS: 000365428100010Introduction and Objective: Monomelic amyotrophy (MA) is a benign motor neuron disease with a stationary stage after a progressive course, involving one or more myotomes in the upper limb. In the early stages, it may be difficult to discriminate the diseases presenting with similar clinical course. We reviewed clinical and EMG characteristics and differential diagnosis of MA for this purpose. Methods: Fourteen cases admitted to the Neurophysiology EMG laboratory of Medical School of Ege University, and diagnosed as having monomelic amytrophy between 2005 and 2014, were evaluated retrospectively along with complaints, age at onset, gender, the involved myotome, EMG and clinical characteristics. Cases with possible etiological diagnoses that might cause mononeuropathy or detected motor conduction block or developed ALS during follow-ups were excluded from the study. Results: All fourteen patients had onset in the upper limb. The female to male ratio was 4: 10, the mean age of the onset was 24 +/- 8.64 years (mean +/- Standard deviation), minimum-maximum age of onset was 16-40 years, with median value being 21. C8-T1 segments were involved in all cases except one. Follow-up EMG studies demonstrated denervation, fasciculations, and reduced compound muscle action potential amplitudes. Electrophysiologically, our three asymptomatic cases had moderate involvement in the contralateral limb without any complaints. Conclusion: Cases with MA can be distinguished from ALS by symptom onset at younger ages in men, its benign course and generally with stabilization of clinical and EMG findings in 2 to 4 years. Asymptomatic side should also be considered to be affected electrophysiologically
