Third (Oculomotor) Nerve Palsy

Third (Oculomotor) Nerve Palsy 2018-01-30T16:37:19+00:00

Relevant physical signs

  • Third nerve palsy
    • Complete oculomotor palsy
      • Complete ptosis
      • Dilated pupil (unopposed sympathetic action)
        • Loss of efferent pupillary reflex on that side
      • Down-and-out eye (unopposed lateral rectus, superior oblique)
    • Partial palsy: any combination of the above
    • Eye movements affected
      • Superior gaze (superior rectus)
      • Inferior gaze (inferior rectus)
      • Adduction (medial rectus)
      • Upward convergence (inferior oblique)
    • Oculomotor nuclei innervate the ipsilateral eye. Exceptions:
      • Superior rectus sub-nucleus sends projections to the contralateral eye
      • Levator palpabrae on both sides innervated by the same central sub-nucleus
  • Isolated third nerve palsies
    • Surgical
      • Parasympathetic fibres located superficially
      • These are more susceptible to compression
      • Surgical third nerve palsies cause ipsilateral pupil dilation
      • Eye movements relatively spared
    • Medical
      • Due to microvascular infarction within the nerve fibres
      • Tend to cause pupil-sparing lesions of the third nerve
  • Features associated with non-isolated palsies
    • Orbital apex syndrome (II, III, IV, V1, VI)
    • Superior orbital fissure syndrome (III, IV, V1, VI)
    • Cavernous sinus syndrome (III, IV, V1, V2, VI, sympathetic fibres)
    • Midbrain syndromes
      • Contralateral hemiparesis – corticospinal tract (Weber’s)
      • Contralateral ataxia – red nucleus (Benedikt’s) / superior cerebellar peduncle (Claude’s)
    • Complex ophthalmoplegia
      • Tachycardia, goitre, tremor – thyroid eye disease
      • Fatigability – ocular myasthenia
      • Grip myotonia – myotonic dystrophy
      • Arreflexia – Miller-Fisher syndrome
      • Scars – trauma, previous surgery

Differential diagnosis

  • Surgical third nerve palsy (compression)
    • Posterior communicating artery aneurysm
  • Medical third nerve palsy (ischaemia)
    • Diabetes mellitus
    • Giant cell arteritis
    • Systemic lupus erythematosus
    • Wegner’s granulomatosis
    • Churg-Strauss syndrome
    • Polyarteritis nodosa
    • Sarcoidosis
  • Complex ophthalmoplegia
    • Thyroid eye disease
    • Ocular myasthenia
    • Miller-Fisher syndrome
    • Myotonic dystrophy
    • Complete progressive external ophthalmoplegia
    • Trauma
    • Orbital cellulitis
  • Midbrain syndromes
    • Weber’s syndrome
    • Claude’s syndrome
    • Benedikt’s syndrome
  • Orbital syndromes
    • Cavernous sinus syndrome
    • Orbital apex syndrome
    • Superior orbital fissure syndrome
  • False localizing sign: Hutchinson’s pupil (dilated pupil)
    • Caused by ipsilateral uncal herniation and compression of the oculomotor nerve

Investigations

  • Magnetic resonance imaging of the brain
    • Midbrain stroke
    • Midbrain space-occupying lesion
  • Magnetic resonance angiogram
    • Posterior communicating artery aneurysm
  • Medical third nerve
    • Cardiovascular risk factors: FPG, HbA1c, lipid monitoring
    • Vasculitic screen: ANA, ANCA, ENA panel
    • Consider temporal artery biopsy and ESR in older patients (GCA)
  • Consider lumbar puncture
    • Bacterial meningitis
    • Leptomeningeal disease

Management

  • Multidisciplinary team approach
  • Patient education
  • Eye patch for diplopia
  • Consider prism therapy for long-standing deficits
  • Consider neurosurgical referral for aneurysm clipping
  • Control cardiovascular risk factors
  • Antiplatelet therapy for secondary prevention of ischaemic events

Third Nerve Palsy

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This Sliding Bar can be switched on or off in theme options, and can take any widget you throw at it or even fill it with your custom HTML Code. Its perfect for grabbing the attention of your viewers. Choose between 1, 2, 3 or 4 columns, set the background color, widget divider color, activate transparency, a top border or fully disable it on desktop and mobile.