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Vestibular System

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Topic updated on 01/16/17 6:19pm

Overview
  • Components 
    • 3 semicircular canals
      • hair cells which respond to angular acceleration/deceleration of head
    • utricle and saccule
      • hair cells which respond to linear acceleration and the force of gravity
  • Role
    • vestibular-occular reflexes
      • doll's head, conjugate eye movements
      • connect to medial longitudinal fasiculus
    • balance
      • connect to flocculonodular lobe of cerebellum
Clinical importance
  • Clinical testing
    • nystagmus with quick-phase correction - caloric testing
      • Cold water
        • nystagmus toward lesion with quick phase to Opposite side
      • Warm water
        • nystagmus to opposite side with quick phase to Same side
      • remember: COWS
  • Vertigo
    • defintion
      • illusion of rotation
        • not to be confused with unsteadiness (cerebellar disease) or lightheadedness (syncope)
      • of vestibular etiology
    • peripheral vertigo
      • more common
      • etiology
        • inner ear
          • benign paroxysmal positional vertigo
            • due to debris in semicircular canal stimulating hair cells
          • vestibular nerve infection
            • MCC herpes simplex virus
          • Meniere's disease
            • buildup of pressure in the cochlea and labyrinth due to excess endolymph
            • abrupt, recurrent attacks of vertigo + deafness/tinnitus is same ear
              • last minutes to hours
      • presentation
        • positional testing → delayed horizontal nystagmus
    • central vertigo
      • etiology
        • brain stem or cerebellar lesion
          • e.g. vestibular nuclei, posterior fossa tumor
      • presentation
        • positional testing → immediate nystagmus in any direction
          • may change directions


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