Neurology >
Cranial Nerve Lesions

“Damage to a cranial nerve through injury or disease”

Aetiology & Management
  • There are many different reasons why a person may experience a cranial nerve lesion including: trauma, tumours, SLE, Herpes Zoster, and various palsies.
  • The presentation is dependent on the location of the lesion and therefore the cranial nerve/s affected.
  • Consequently, management and any complications are largely dependent on the cause of the lesion.
CNI – Olfactory Nerve
  • Clinical Presentation:
    • Anosmia
  • Examination:
    • Ask if they have noticed any change in their sense of smell
CNII – Optic Nerve
  • Clinical Presentation:
    • Visual field defects dependent on the location of the lesion
  • Examination:
    • Pupil inspection
    • Visual acuity
    • Pupillary reflexes
    • Colour vision
    • Visual fields
    • Fundoscopy
CNIII – Oculomotor Nerve
  • Clinical Presentation:
    • Eye in down and out position
    • Ptosis
    • Mydriasis
  • Examination:
    • Assess eye movements & cover test.
    • Ask about double vision
CNIV – Trochlear Nerve
  • Clinical Presentation:
    • Eye in down and in position
    • Diplopia
  • Examination:
    • Assess eye movements & cover test.
    • Ask about double vision
CNV – Trigeminal Nerve
  • Clinical Presentation:
    • Loss of sensation in the face
    • Weakness in jaw
  • Examination:
    • Assess light and pinprick sensation in forehead, cheek and jaw.
    • Check muscle wasting in masseter and temporalis muscle bilaterally.
      • Open mouth under resistance.
      • Assess jaw jerk reflex.
CNVI – Abducens Nerve
  • Clinical Presentation:
    • Eye deviates medially
  • Examination:
    • Assess eye movements & cover test.
    • Ask about double vision
CNVII – Facial Nerve
  • Clinical Presentation:
    • UMN
      • Paralysis of facial muscles on contralateral side with forehead sparing
    • LMN
      • Paralysis of the upper and lower face on one side
      • Loss of taste to anterior 2/3 of tongue
      • Hyperacusis
      • Dry eyes
  • Examination:
    • Inspect patients face for asymmetry and ask the patient to perform facial movements to check facial muscles.
    • Ask if they have noticed any changes in hearing and taste.
    • Inspect external auditory meatus
CNVIII – Vestibulocochlear Nerve
  • Clinical Presentation:
    • Deafness
    • Vertigo
  • Examination:
    • Perform a gross hearing test, Rinne’s test and Weber’s test.
    • Asses vestibular function through a turning test and head thrust test
CNIX – Glosopharyngeal Nerve
  • Clinical Presentation:
    • Uvular deviation
    • Decreased gag reflex
  • Examination:
    • Assess the soft palate and uvula.
    • Check gag reflex, ask the patient to cough to check for a bovine cough, and assess swallowing
CNX – Vagus Nerve
  • Clinical Presentation:
    • Dysphagia
    • Hoarse voice
    • Problems with parasympathetic supply of thoracic and abdominal viscera
  • Examination:
    • Assess the soft palate and uvula.
    • Check gag reflex, ask the patient to cough to check for a bovine cough, and assess swallowing
CNXI – Spinal Accessory Nerve
  • Clinical Presentation:
    • Inability to shrug
    • Poor head movement
  • Examination:
    • Ask the patient to shrug shoulders and turn head to one side against resistance.
CNXII – Hypoglossal Nerve
  • Clinical Presentation:
    • Deviated tongue
  • Examination:
    • Assess the power of the tongue and ask the patient to protrude tongue to check for deviation
Quick Revision Sheet

Access an overview table of the Cranial Nerve Lesions here (pdf)

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