Stereotypy - Purposeful, voluntary movements performed repetitively, such as body-rocking and head-banging, caused by dopamine blockade

Tics - Rare following TBI

• Usually occur for brief periods during normal activity in response to an uncomfortable sensation and disappear during sleep and pleasurable activities
• Include motor tics, such as shrugs, head shakes, and grimacing, and phonic tics, such as sniffing, snorting, or obscene utterances
• Probably caused by aberrant sprouting of peripheral facial nerves, dopamine antagonists, or methylphenidate
• Therapy with clonazepam and clonidine produces varying results

Tremor - The most common involuntary movement

• Characterized by rhythmic and oscillatory movements that can occur at any time postinjury, and produced by contractions of antagonistic muscle groups

• Classified as
  • Action or intention tremors
    • Postural tremors are evident during sustained contraction of antigravity muscles
    • Kinetic tremors are evident during the beginning, course, or end of a movement
    • Position-specific tremors are evident during specific activities or postures
    • Isometric tremors are evident during voluntary isometric movements
  • Resting tremors

• Assessed through videotaping; quantified through surface electromyography, accelerometer recordings, and frequency analysis; most tremors have a frequency of 4-10 Hz
  • Cerebellar tremors have a frequency of 4-5 Hz
    • Caused by damage to the cerebellum or its connections
    • Become exaggerated during fine, precise activity and worsen with stress
    • May be accompanied by nystagmus, ataxia, or dysarthria
    • Disappear during sleep
  • Slow tremors have a frequency of 1-3 Hz and are usually due to brainstem damage
  • Fast tremors have a frequency of 11-20 Hz

• Treatment includes
  • Botulinum toxin injections
  • Pharmacologic agents such as
    • Propranolol, clonazepam, and valproic acid for physiologic tremor, which are useful but can cause side effects such as fatigue, sedation, and memory impairment
    • Arotinolol for essential tremor
    • Clonidine to desynchronize tremor
    • Levodopa for rubral (midbrain) tremor
  • Thalamic stimulation
  • Stereotactic thalamotomy for severe, disabling tremor to alleviate tremor and improve functional disability (Krauss, et al 1994)