Abducens nerve palsy

Background

  • Also called 6th cranial nerve (CN VI)
  • Most common ocular nerve palsy
  • Innervates the ipsilateral lateral rectus muscle controlling eye abduction
  • Esotropia (eye moves inward) of the affected eye due to the unopposed action of the medial rectus muscle, innervated by the oculomotor nerve (CN III) [1]

Causes

Clinical Features

History

Examination

  • Excluding paresis of the other cranial nerves
  • Check ocular muscle movements
  • Check for papilledema
  • Test pupillary response
  • Test ocular motor nerves (CN III, IV, and VI)[3][4]
    • Trace a full H-pattern with finger and have the patient follow the finger only with their eyes
    • Patients with abducens nerve palsy are unable to move the affected eye laterally
    • In order to avoid diplopia, patients will turn their heads away from the lesion so that both eyes are looking sideways
    • Check deep tendon reflexes and strength to exclude corticospinal tract involvement

Differential Diagnosis

Evaluation

Work-up

  • Workup will depend on suspected etiology, may include
    • POC glucose
    • CBC
    • BMP
    • ESR
    • Lyme titer
    • RPR (if suspect syphilis)
    • Lumbar puncture to exclude meningitis, Guillain-Barré
    • Antinuclear antibody test
    • CT head: exclude acute bleed or mass
    • MRI: indicated for brainstem findings on the exam and to exclude pontine glioma in children and in adults where the abducens nerve palsy does not improve[3][4]

Management

  • Treat by underlying etiology
  • Consider neuro/optho consult
  • Children: Can be treated with alternating patching to decrease probability of developing amblyopia in the affected eye
  • Adults: Lenses can be fogged with clear tape, paint, or nail polish to decrease diplopia. Neurology can prescribe Fresnel prisms as an alternative.
  • Giant cell arteritis: treat with prednisone or intravenous Methylprednisolone.

Disposition

  • Dispo appropriate to etiology
  • Truly isolated cases: often benign, can be followed up by neurologist for serial exams
  • Surgery: If patient does not improve within 6 months after treatment and serial check-ups, surgery may be required[3][4]

See Also

External Links

References

  1. 1.0 1.1 1.2 Tintinalli JE, Kelen GD, Stapczynski JS, Ma, OJ, Cline DM, editors. Tintinalli’s Emergency Medicine. 7th ed. New York: McGraw-Hill; 2011. 763, 1037, 1546
  2. 2.0 2.1 Marx JA, Hockberger RS, Walls RM, et al., eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Philadelphia, PA: Mosby/Elsevier; 2013
  3. 3.0 3.1 3.2 3.3 Yanoff M, Duker JS. Opthalmology. Mosby International Ltd; 2013
  4. 4.0 4.1 4.2 4.3 Gerstenblith AT. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease. Lippincott Williams and Wilkins
  5. http://www.ncbi.nlm.nih.gov/pubmed/26314216
  6. http://www.ncbi.nlm.nih.gov/pubmed/17157701
  7. http://www.ncbi.nlm.nih.gov/pubmed/11555800