Observation of regenerated fungiform taste buds after severing the chorda tympani nerve using confocal laser scanning microscopy in vivo.
OBJECTIVE
To evaluate whether regenerated fungiform taste buds after severing the chorda tympani nerve can be detected by confocal laser scanning microscopy in vivo.


METHODS
Retrospective study.


METHODS
University hospital.


METHODS
Six patients with a normal gustatory function (Group 1), 9 patients with taste function recovery after severing the CTN (Group 2), and 5 patients without taste function recovery (Group 3) were included. In Groups 2 and 3, canal wall up (closed) tympanoplasty or canal wall down with canal reconstruction tympanoplasty was performed in all patients.


METHODS
Diagnostic.


METHODS
The severed nerves were readapted or approximated on the temporalis muscle fascia used to reconstruct the eardrum during surgery. Preoperative and postoperative gustatory functions were assessed using electrogustometry. Twelve to 260 months after severing the CTN, the surface of the midlateral region of the tongue was observed with a confocal laser microscope.


RESULTS
EGM thresholds showed no response 1 month after surgery in all patients of Groups 2 and 3. In Group 2, EGM thresholds showed recovery 1 to 2 years after surgery and before confocal microscopy (-1.3 ± 6.5 dB). There was a significant difference between Group 1 (-5.7 ± 2.0 dB; p < 0.01) and Group 2. In Group 3, EGM thresholds showed no response for more than 2 years. In the control group (Group 1), 0 to 16 taste buds were observed in each FP, and 55 (79.7%) of 69 FP contained at least 1 taste bud. The mean number of taste bud per papilla was 3.7 ± 3.6. In patients with a recovered taste function (Group 2), 0 to 8 taste buds were observed in each FP. In this group, 54 (56.2%) of 94 FP contained at least 1 taste bud. The mean number of taste bud per papilla was 2.0 ± 2.2 (p < 0.01). In Group 3, without recovery, the FP was atrophied, and no taste bud was observed.


CONCLUSIONS
Regenerated fungiform taste bud could be observed in vivo using confocal laser scanning microscopy, indicating that regenerated taste bud can be detected without biopsy.
*Department of Otolaryngology, Head and Neck Surgery; †Department of Anatomy, Faculty of Medicine; and ‡Research and Education Program for Life Science, University of Fukui, Fukui, Japan.
Takehisa
T
Saito
Tetsufumi
T
Ito
Yuji
Y
Kato
Takechiyo
T
Yamada
Yasuhiro
Y
Manabe
Norihiko
N
Narita
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002814:Chorda Tympani Nerve / Q000293:injuries*; D005260:Female; D006801:Humans; D018613:Microscopy, Confocal; 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*; D014059:Tongue / Q000294:innervation; D014433:Tympanoplasty / Q000009:adverse effects; D055815:Young Adult