Cranial Nerves

Facial Nerve CN 7

• 6 Segments

  • Cisternal segment = part where it comes of brainstem but before it enters the IAC

  • Canalicular segment = part where it first enters the IAC

  • Labyrinthine segment = distal IAC to the geniculate ganglion

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• Disease of Facial nerve

  • Bell’s Palsy/Ramsay-Hunt Disease

    • Enhancement of cranial nerve (canalicular through tympanic segments usually)

    • Ramsay hunt has additional facial rash

  • Lyme Disease

    • Enhancement of multiple nerves but CN7 is most commonly involved

    • Bilateral CN7 enhancement is essentially pathognomonic (although unilateral more common)

  • The two above show nerve enhancement but not enlargement, if there is enlargement masses or metastatic disease should be considered

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