Ataxia

Background

• Sign of a variety of disease processes; not a diagnosis in its self
• Isolated lesion of cerebellum is NOT the most common cause
• Must distinguish between motor (cerebellar) and sensory (cord, peripheral nerves) ataxia
  • Sensory ataxia may be compensated to a degree w/ visual sensory information

Diagnosis

1. Sensory versus motor ataxia
   1. Romberg test
      1. Comparison of posture stability when eyes are open versus eyes closed
      2. If ataxia worsens w/ loss of visual input suggestive of sensory ataxia
      3. If ataxia does not significantly change w/ eyes closed suggests motor ataxia
2. Systemic versus isolated nervous system disease
3. CNS versus PNS
4. Cerebellar versus posterior column (proprioceptive)
   1. Finger to nose
      1. Performing test w/ eyes closed tests proprioception
   2. Heel-to-shin test
      1. Posterior column disease: Difficult locating knee
      2. Cerebellar disease: Action completed w/ series of jerky movements

Work-Up

• Depends on rapidity of symptoms
• If acute consider CT, MRI, LP

DDX

1. Systemic conditions
   1. Intoxications with diminished alertness
      1. Ethanol
      2. Sedative-hypnotics
   2. Intoxications with relatively preserved alertness
      1. Phenytoin
      2. Carbamazepine
      3. Valproic acid
      4. Lead, organic mercurials
   3. Other metabolic disorders
      1. Hyponatremia
      2. Inborn errors of metabolism
      3. Wernicke's disease
2. Disorders predominantly of the nervous system
   1. Conditions affecting predominantly one region of the CNS
      1. Cerebellum
         1. Hemorrhage
         2. Infarction
         3. Degenerative changes
         4. Abscess
      2. Cortex
         1. Frontal tumor, hemorrhage, or trauma
         2. Hydrocephalus
      3. Subcortical
         1. Thalamic infarction or hemorrhage
         2. Parkinson's disease
         3. Normal pressure hydrocephalus
      4. Spinal cord
         1. Cervical spondylosis
         2. Posterior column disorders
   2. Conditions affecting predominantly the peripheral nervous system
      1. Peripheral neuropathy
      2. Vestibulopathy

Source

Tintinalli