Vol.100 No.11 contentsPRACTICA OTO-RHINO-LARYNGOLOGICA
Vol. 100 No. 11 November 2007
Regeneration of the Chorda Tympani Nerve and
Fungiform Papillae after Middle Ear Surgery
Takehisa Saito
(University of Fukui, School of Medicine)
The chorda tympani nerve is often severed during middle ear surgery. After being severed, regeneration of the nerve was observed in 46％ (33/71 ears) of patients who underwent second surgery or re-operation. Since it is unclear whether these regenerated nerves have gustatory function, the threshold of electrogustometry (EGM) was measured periodically over a one-year period after surgery. In 20 (61％) of 33 cases demonstrating regenerated nerves, EGM threshold recovered completely or incompletely compared with pre-operative values. Furthermore, the morphological examination of fungiform papillae of the tongue using a digital microscope was performed. In 35 patients with recovery of gustatory function, 11 (31％) showed a similar size and distribution of fungiform papillae compared with that on the non-severed side. Based on these findings, it was concluded that the severed chorda tympani nerve can regenerate and regain gustatory function. Furthermore, it was suggested that the regenerated chorda tympani nerve fibers distribute to fungiform taste buds, although morphological study of the taste buds using a transmission electron microscope is needed.
Key words : regeneration, chorda tympani nerve, fungiform papillae, middle ear surgery, gustatory
function