Distal Cervical Spondylotic Amyotrophy: Case Reports Demonstrating Clinical/Imaging Segmental Discrepancy

J Clin Neuromuscul Dis. 2019 Dec;21(2):107-111. doi: 10.1097/CND.0000000000000268.

Abstract

Monomelic pure motor amyotrophy may seem to be an ominous syndrome as it leads to consideration of motor neuron disease. We present a series of 3 very similar cases where unilateral pure distal lower motor neuron paresis and atrophy was limited to the C8-T1 myotomes, without long-tract signs. Electrodiagnostic studies were in keeping with a restricted anterior horn cell disorder. Neuroimaging showed very focal spinal cord compression at the C6-7 level. Two patients underwent surgical decompression. All 3 patients were improved or stable at follow-up. Distal spondylotic amyotrophy is characterized by equal involvement of thenar and hypothenar muscles, in contrast to amyotrophic lateral sclerosis or Hirayama disease. We discuss the striking 2-level discrepancy between imaging and clinical localization. Proposed explanations are arterial or venous compromise caudal to the site of compression. Anatomical variation such as a prefixed brachial plexus is unlikely. A similar imaging/clinical discrepancy has been documented in Hirayama disease and spondylotic myelopathy.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Aged
  • Amyotrophic Lateral Sclerosis / diagnostic imaging
  • Back Muscles / diagnostic imaging
  • Cervical Vertebrae / diagnostic imaging*
  • Diagnosis, Differential
  • Electrodiagnosis
  • Female
  • Humans
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Motor Neuron Disease / pathology
  • Motor Neurons / pathology
  • Muscle Weakness
  • Muscular Atrophy / diagnostic imaging
  • Muscular Atrophy / etiology
  • Neural Conduction
  • Spinal Cord Compression / diagnostic imaging
  • Spinal Muscular Atrophies of Childhood / diagnostic imaging*

Supplementary concepts

  • Amyotrophy, monomelic