title: Length of nerve gap defects correlates with incidence of nerve regeneration but not with recovery of taste function in patients with severed chorda tympani nerve.
abstract: OBJECTIVE
  To evaluate the relationship between the length of nerve gap defects, incidence of nerve regeneration, and recovery of gustatory function after severing the chorda tympani nerve (CTN).
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  University hospital.
  
  
  METHODS
  Eighty-eight consecutive patients whose CTNs were severed during primary surgery and who underwent secondary surgery were included. Proximal and distal stumps of severed nerves were readapted or approximated during surgery.
  
  
  METHODS
  Therapeutic.
  
  
  METHODS
  Before and after surgery, the taste function was periodically evaluated using electrogustometry. Nerve gaps were classified into 4 groups: readaptation (Group 1), 1 to 3 mm (Group 2), 4 to 6 mm (Group 3), and more than 7 mm (Group 4).
  
  
  RESULTS
  Regenerated nerves in the tympanic segment were detected in 36 (41%) of the 88 patients during secondary surgery. The incidence of nerve regeneration was 100% (10/10) in Group 1, 45% (10/22) in Group 2, 47% (9/19) in Group 3, and 19% (7/37) in Group 4. There was a significant difference between the length of nerve gap defects and incidence of nerve regeneration (p < 0.001). In the 36 patients with a regenerated CTN, the incidence of gustatory function recovery was 60% (6/10) in Group 1, 50% (5/10) in Group 2, 56% (5/9) in Group 3, and 43% (3/7) in Group 4. There was no significant difference between the length of nerve gap defects and incidence of taste function recovery.
  
  
  CONCLUSIONS
  Reconstruction of a severed CTN is very important for regeneration. However, the regenerated CTN in the tympanic segment does not always reinnervate the fungiform papillae.
authors: Department of Otolaryngology, Head and Neck Surgery, Faculty of Medicine, University of Fukui, Japan. takehisa@u-fukui.ac.jp
authors: Takehisa
authors: T
authors: Saito
authors: Norihiko
authors: N
authors: Narita
authors: Takechiyo
authors: T
authors: Yamada
authors: Kazuhiro
authors: K
authors: Ogi
authors: Masafumi
authors: M
authors: Kanno
authors: Yasuhiro
authors: Y
authors: Manabe
authors: Tetsufumi
authors: T
authors: Ito
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002814:Chorda Tympani Nerve / Q000293:injuries* / Q000502:physiology* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009416:Nerve Regeneration / Q000502:physiology*; D020127:Recovery of Function / Q000502:physiology*; D012189:Retrospective Studies; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000502:physiology; D013652:Taste Threshold / Q000502:physiology