Ataxia and gait disturbance

Introduction

• Ataxia often erroneously considered due to cerebellar dysfunction
• Isolated lesions of cerebellum are not the most common cause
• Ataxia divided into motor and sensory
• Can divide into systemic and primary CNS lesions

Differential

• Systemic
  • Intoxication with diminished alertness – Ethanol, sedatives
  • Intoxications with preserved alertness – Phenytoin, carbamazepine, valproic acid, heavy metal intoxication
  • Other metabolic disorders – Hyponatraemia, inborn errors of metabolism, Wernicke’s

Differential

• Disorders of nervous system
  • Cerebellar – Haemorrhage, tumor, infarction, degeneration, abscess
  • Cortex – Frontal tumor/haemorrhage/trauma, hydrocephalus
  • Subcortical – Thalamic infarction/haemorrhage, Parkinson’s, normal pressure hydrocephalus
  • Spinal cord – Spinal cord compression, posterior column disease
  • Peripheral neuropathy
  • Vestibulopathy

Motor ataxias

• Aka cerebellar ataxias
• Lateral cerebellar lesions lead to ipsilateral limb signs
• Midline cerebellar lesions lead to axial incoordination
• Supratentorial lesions
  • Small, deep infarctions
  • Lacunae of posterior limb of internal capsule
• Thalamic nuclei infarction or haemorrhage can also produce motor ataxia with hemisensory loss
• Frontal lobe lesions can cause contralateral motor ataxia through poorly understood mechanisms
• Spinal cord compression can also present with motor ataxia

Sensory ataxias

• Can be due to peripheral nerve, dorsal column or cerebellar input tract dysfunction
• Can be compensated for by visual sensory inputs
• Closed eye testing often exacerbates the issue

Gait disorders

• Cerebellar/motor ataxic gait
  • Wide-based, unsteady irregular steps
• Sensory ataxia
  • Abrupt movement of legs and slapping impact of feet
• Apraxic gait
  • Ignition failure due to right or non-dominant hemispheric lesions
  • Frontal lobe dysfunction and normal pressure hydrocephalus can also lead to this
• Festinating gait
  • Narrow based, miniature shuffling steps in Parkinson’s

Gait disorders

• Circumduction gait
  • Outward swinging leg due to mild hemiparesis reflecting weakness of proximal lower extremity muscles
• Waddling gait
  • Due to bilateral weakness of trunk and pelvic girdle muscles
• Functional gait disorder
  • All testing normal but bizarre gait often resembling tightrope walking and threatening to fall but not
  • Dramatic functional gaits without falling actually demonstrate strength, balance and coordination are intact

Clinical features

• Hx
  • Duration of onset
  • Fever
  • Headache
  • FHx of ataxia
  • Review of medications
  • Associated symptoms
• Examination
  • Full neuro including cognition/alertness
  • Orthostatic vital signs
    • In the elderly, fluid replacement often corrects any unsteadiness
  • Gait testing
  • Cerebellar testing

Examination

• Gait testing
  • Sitting
  • Standing, walk, turn and walk back
  • Heel walking and toe walking
• Cerebellar vs. posterior column disease
  • Finger-nose testing: Testing with eyes closed identifies proprioceptive failure
  • Heel-shin testing:
    • Cerebellar: Heel may overshoot knee and then series of jerky movements
    • Posterior column: Difficulty locating the knee, heel weaves down shin or falls off

Examination

• Rombergs
  • Stand with eyes open and arms outstretched
  • Inability to maintain standing posture (or sitting in extreme cases) confirms ataxia but not what type
  • Then close eyes, eliminating visual postural cues
  • If ataxia worsens, then Romberg’s positive = sensory ataxia with problem of proprioceptive input e.g. posterior columns. vestibular disease or peripheral neuropathy
  • If no change (negative), suggests motor ataxia

Examination

• Tabes dorsalis (neurosyphilis)
  • Presents with wide-based slow gait staring at ground and cannot walk in darkness or with eyes closed
  • Due to loss of posterior column lower limb input
• B12 deficiency
  • Also causes posterior column dysfunction
  • Initial unsteady gait can progress to weakness, ataxia and spasticity
• Sensory examination
  • Always include proprioceptive testing sensation to pinprick
• Nystagmus
  • Suggests process is intracranial vs. spinal cord or peripheral nervous system
  • Non-specific for actual cause

Geriatric patients

• Gait becomes slowed, shortened stride and widened base with age
• = Guarded gait
• Seen in 25% of elderly patients
• Also seen in Parkinson’s or normal pressure hydrocephalus

Last Updated on October 28, 2020 by Andrew Crofton