Cervical spinal cord (C1-C5)

Disease in this region of the spinal cord typically leads to weakness and incoordination in all four limbs due to disease affecting descending upper motor neuron (UMN) tracts and ascending proprioceptive fibers, respectively. Lower motor neurons in the gray matter of the C1-C5 spinal cord primarily innervate cervical muscles. However, clinical signs are usually not readily apparent on neurologic exam.

Common clinical signs of cervical (C1-5) myelopathy

  • Weakness/paralysis and/or ataxia in all 4 limbs (tetraparesis/tetraplegia), ipsilateral limbs (hemiparesis/hemiplegia) or only one thoracic limb (monoparesis/monoplegia)
  • UMN signs in all 4 limbs
    • Normal to exaggerated spinal nerve reflexes
    • Normal withdrawal reflex all 4 limbs
    • Normal to increased muscle tone in affected limbs
  • Late disuse muscle atrophy
  • Cervical vertebral discomfort, muscles spasms, rigidity
  • +/- UMN bladder
  • +/- Respiratory difficulty (UMN dysfunction to phrenic and intercostal nerves)
  • +/- Horner Syndrome (1st order sympathetic neurons)

Case example of a cat with a cervical myelopathy due to a C2-C4 fibrocartilaginous embolic myelopathy.