title: A case of cyclic superior oblique paresis.
abstract: BACKGROUND
  Cyclic strabismus, which generally has a 24 hours on-off cycle, is an unusual but interesting form of ocular motor disorder. Cyclic deviations are characterized by periods of significant deviation followed by periods of strict orthotropia. In the orthotropic periods, binocular sensoriality and motricity are normal. During the symptomatic phase, in which the deviation is usually significant and permanent, certain sensory anomalies can be found. Although most referred cases are cyclic esotropia, other cyclic oculomotor disorders have been described. In this report, we present a case with a 24 hours on-off cycle superior oblique paresis that resolved with surgery performed during the alternate day rhythm period.
  
  
  METHODS
  A 43 year old woman developed an alternate day hypertropia with bothersome diplopia. During the 24 hour "on" cycles she showed a unilateral left superior oblique paresis. The deviation had onset spontaneously 10 years ago with no previous history of strabismus, surgery or trauma. Following left inferior oblique recession and right inferior rectus recession surgery, the eyes have been straight and the cyclic pattern abolished.
  
  
  CONCLUSIONS
  Cyclic vertical deviation due to a superior oblique paresis can be operated on by means of current surgical procedures in the course of the on-off cycle stage; i.e., before the cyclic pattern has been abolished and the deviation becoming permanent.
authors.affiliation: Instituto Prieto-Diaz de Oftalmologia, La Plata and the Instituto Oftalmologico de Rosario, Argentina. jprieto@netverk.com.ar
authors.forename: Julio
authors.initials: J
authors.lastname: Prieto-Diaz
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Gallo
mesh_terms: D000328:Adult; D004172:Diplopia / Q000209:etiology* / Q000601:surgery; D005260:Female; D006801:Humans; D009801:Oculomotor Muscles / Q000601:surgery*; D013508:Ophthalmologic Surgical Procedures; D010507:Periodicity; D013285:Strabismus / Q000209:etiology* / Q000601:surgery; D020432:Trochlear Nerve Diseases / Q000150:complications* / Q000601:surgery