title: The chorda tympani degenerates during chronic otitis media: an electron microscopy study.
abstract: CONCLUSIONS
  Chorda tympani nerve specimens from ears with chronic inflammatory middle ear disease exhibit structural signs of degeneration. These correlate well with taste disturbance. Simultaneously, they exhibit signs of regeneration, which may explain the ability for taste recovery.
  
  
  OBJECTIVE
  The chorda tympani, the major taste nerve, runs uncovered through the middle ear cavity. This situation exposes it to various forms of middle ear pathology. A difference has been noticed regarding taste symptoms pre- and postoperatively between inflammatory and non-inflammatory diseases. The present study aimed to investigate ultrastructural changes of chorda tympani in different forms of inflammatory middle ear disease, such as chronic suppurative otitis media and cholesteatoma, as compared with normal.
  
  
  METHODS
  Five chorda tympani specimens were collected from healthy middle ears of patients subjected to surgery for acoustic neuroma, to be used as normal controls, and five from middle ears with chronic otitis media or cholesteatoma, where the nerve could not be saved during the operation. Light and electron microscopy were performed.
  
  
  RESULTS
  For all five nerves from diseased ears, microscopy showed a higher percentage of axon and myelin sheath degeneration than in the normal controls. Furthermore, three of the five also exhibited sprouting.
authors.affiliation: Centre for Clinical Research, Uppsala University, County Hospital , Västerås , Sweden.
authors.forename: Katarina
authors.initials: K
authors.lastname: Berling
authors.forename: Paula
authors.initials: P
authors.lastname: Mannström
authors.forename: Mats
authors.initials: M
authors.lastname: Ulfendahl
authors.forename: Niklas
authors.initials: N
authors.lastname: Danckwardt Lillieström
authors.forename: Magnus
authors.initials: M
authors.lastname: von Unge
mesh_terms: D016022:Case-Control Studies; D018424:Cholesteatoma, Middle Ear / Q000473:pathology*; D002814:Chorda Tympani Nerve / Q000648:ultrastructure*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D010033:Otitis Media / Q000473:pathology*
keywords: Taste; degeneration; otosurgery; sprouting