Monomelic amyotrophy of upper limb (Q83612)

Monomelic amyotrophy of the upper limb is characterised by slowly progressive, asymmetric weakness most commonly of distal muscles innervated by the C8 and T1 spinal segments. Rarely MMA may present with only proximal upper limb weakness. Asymptomatic or mild involvement of the contralateral upper limb is common. Weakness is usually slowly progressive before reaching a plateau, and symptomatic weakness may spread to the opposite limb. MRI may show focal cervical spinal cord atrophy.