title: Incidence, associations, and evaluation of sixth nerve palsy using a population-based method.
abstract: OBJECTIVE
  To determine the incidence of sixth nerve palsy in a population-based study, with particular emphasis on associated coexisting medical conditions and to use these data to develop a management algorithm.
  
  
  METHODS
  Retrospective, population-based case series.
  
  
  METHODS
  All residents of Olmsted County, Minnesota, USA, diagnosed with sixth nerve palsy between January 1, 1978 and December 31, 1992.
  
  
  METHODS
  All cases were identified by using the Rochester Epidemiology Project medical records linkage system, which captures all patient-physician encounters in Olmsted County. The entire medical record of each patient was reviewed to confirm the diagnosis, document county residency, and to determine associated medical conditions. We used stringent predetermined criteria to define diabetes mellitus and hypertension as associations. Incidence rates were adjusted to the age and gender distribution of the 1990 white population in the United States.
  
  
  METHODS
  Etiology or systemic associations of the palsy.
  
  
  RESULTS
  We identified 137 new cases of sixth nerve palsy over the 15-year period. The age- and gender-adjusted annual incidence of sixth nerve palsy was 11.3/100 000 (95% confidence interval, 9.3-13.2/100 000). Causes and associations were: undetermined (26%), hypertension alone (19%), coexistent hypertension and diabetes (12%), trauma (12%), multiple sclerosis (7%), neoplasm (5%), diabetes alone (4%), cerebrovascular accident (4%), postneurosurgery (3%), aneurysm (2%), and other (8%). When sixth nerve palsy was the presenting sign in cases of neoplasm (n = 1) and aneurysm (n = 3), history and examination revealed the presence of other neurologic symptoms or signs.
  
  
  CONCLUSIONS
  We provide population-based data on the incidence of sixth nerve palsy with a notably lower incidence of neoplasm and higher incidence of diabetes and hypertension than previous institution-based series. We suggest that patients with nontraumatic neurologically isolated sixth nerve palsy may undergo a focused medical evaluation followed by close observation, whereas non-neurologically isolated cases warrant a full neurologic evaluation, including prompt neuroimaging.
authors.affiliation: Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota 55905, USA. holmes.jonathan@mayo.edu
authors.forename: Sanjay V
authors.initials: SV
authors.lastname: Patel
authors.forename: Srinivas
authors.initials: S
authors.lastname: Mutyala
authors.forename: David A
authors.initials: DA
authors.lastname: Leske
authors.forename: David O
authors.initials: DO
authors.lastname: Hodge
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Holmes
mesh_terms: D020434:Abducens Nerve Diseases / Q000453:epidemiology*; D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000783:Aneurysm / Q000453:epidemiology; D002648:Child; D015897:Comorbidity; D003920:Diabetes Mellitus / Q000453:epidemiology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D015994:Incidence; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D009103:Multiple Sclerosis / Q000453:epidemiology; D009369:Neoplasms / Q000453:epidemiology; D012189:Retrospective Studies; D017678:Sex Distribution; D020521:Stroke / Q000453:epidemiology; D014947:Wounds and Injuries / Q000453:epidemiology