title: Differential diagnosis and management of acquired sixth cranial nerve palsy.
abstract: BACKGROUND
  Cranial nerve VI innervates the lateral rectus muscle. A lesion will result in esotropia greater at distance and an ipsilateral abduction deficiency. After the age of 50 years, vascular diseases are the most commonly known causes.
  
  
  METHODS
  A 55-year-old white man reporting a 2-week history of horizontal diplopia that was worse at distance was found to have a left sixth cranial nerve paresis. The patient was diagnosed with hypertension and placed on medications. At the 4-week follow-up visit, the abduction deficiency had resolved.
  
  
  CONCLUSIONS
  The incidence of sixth nerve palsy is 11.3 in 100,000. A lesion anywhere along the course of the nerve, from the pons to the orbit, can cause a paresis or palsy. After ruling out trauma and non-neurological problems, cases should be classified into neurologically isolated or non-neurologically isolated cases. Neurologically isolated sixth nerve palsies are associated most commonly with vascular disease. Non-neurologically isolated sixth nerve palsies typically are associated with more grave conditions.
  
  
  CONCLUSIONS
  A sixth nerve palsy of vascular or undetermined causes typically resolves within 6 to 8 weeks. If resolution does not occur within 2 to 3 months, the condition progresses, or if additional neurologic signs or symptoms develop, imaging studies are indicated.
authors.affiliation: Pacific University College of Optometry, Forest Grove, Oregon 97116, USA. goodwin@pacificu.edu
authors.forename: Denise
authors.initials: D
authors.lastname: Goodwin
mesh_terms: D020434:Abducens Nerve Diseases / Q000150:complications / Q000175:diagnosis* / Q000628:therapy; D003937:Diagnosis, Differential; D004172:Diplopia / Q000175:diagnosis* / Q000209:etiology / Q000628:therapy; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009801:Oculomotor Muscles / Q000294:innervation / Q000503:physiopathology; D012683:Sensory Deprivation