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Título

Cervical spondylotic amyotrophy: a rare cause of focal peripheral nerve hyperexcitability syndrome.

RESUMO

Case Presentation: A 47 year-old man presented to the emergency department reporting involuntary movements and weakness in the right upper limb in the previous 28 days. These symptoms were associated with paresthesia and neuropathic pain. Neurological examination showed myokymia, fasciculation and distal weakness in the right upper limb, a claw hand, atrophy of the hypothenar eminence, and asymmetrical response of the right finger flexion reflex. A magnetic resonance imaging (MRI) of the cervical spine showed a C5-C6 spondylotic compression of the spinal cord with a "snake eye sign". Electroneuromyography showed an axonal compromise of the preganglionic portion of the C7-C8 myotomes. Myokymia, fasciculation and pain had a significant improvement with carbamazepine. Discussion: Cervical spondylotic amyotrophy is characterized by predominantly motor symptoms related to compression of the ventral neural root or injury to the anterior horn due to cervical spondylosis. The intrinsic injury to the anterior horn can be related to insufficient blood supply, which was demonstrated by high intensity signal in the spinal cord, the so-called snake-eye sign. Peripheral nerve hyperexcitability syndrome (PNHS) is characterized by cramps, fasciculations, neuromyotonia and myokymia. PNHS is usually associated with autoimmune disorders such as in the presence of anti-CASPR2 autoantibodies, but can also occur in channelopathies, amyotrophic lateral sclerosis, and, rarely, cervical spondylotic amyotrophy. Conclusion: Focal PNHS should include cervical spondylotic amyotrophy in its differential diagnosis.

Palavras Chave

Key Words: anterior horn, spinal cord compression, fasciculation, peripheral hyperexcitability syndrome.