The effect of systemic lipoic acid on hearing preservation after cochlear implantation via the round window approach: A guinea pig model.
The present study aimed to evaluate the effects of systemic lipoic acid on hearing preservation after cochlear implantation. Twelve Dunkin-Hartley guinea pigs were randomly divided into two groups: the control group and the lipoic acid group. Animals in the lipoic acid group received lipoic acid intraperitoneally for 4 weeks. A sterilised silicone electrode-dummy was inserted through the round window to a depth of approximately 5 mm. The hearing level was measured using auditory brainstem responses (ABRs) prior to electrode-dummy insertion, and at 4 days and 1, 2, 3 and 4 weeks after electrode-dummy insertion. The threshold shift was defined as the difference between the pre-operative threshold and each of the post-operative thresholds. The cochleae were examined histologically 4 weeks after electrode-dummy insertion. Threshold shifts changed with frequency but not time. At 2kHz, ABR threshold shifts were statistically significantly lower in the lipoic acid group than the control group. At 8, 16 and 32kHz, there was no significant difference in the ABR threshold shift between the two groups. Histologic review revealed less intracochlear fibrosis along the electrode-dummy insertion site in the lipoic acid group than in the control group. The spiral ganglion cell densities of the basal, middle and apical turns were significantly higher in the lipoic acid group compared with the control group. Therefore, systemic lipoic acid administration appears to effectively preserve hearing at low frequencies in patients undergoing cochlear implantation. These effects may be attributed to the protection of spiral ganglion cells and prevention of intracochlear fibrosis.
Department of Otorhinolaryngology-Head and Neck Surgery, Chung-Ang University College of Medicine, 102 Heukseok-ro, Dongjak-gu, Seoul, 06973, South Korea.
Mun Young
MY
Chang
Department of Electrical and Computer Engineering, School of Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea.
Tae Mok
TM
Gwon
Department of Otorhinolaryngology-Head and Neck Surgery, Boramae Medical Center, Seoul Metropolitan Government-Seoul National University, 20 Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, South Korea.
Ho Sun
HS
Lee
Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Seoul National University, 103 Daehak-ro, Jongno-gu Seoul, 03080, South Korea.
Jun Ho
JH
Lee
Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Seoul National University, 103 Daehak-ro, Jongno-gu Seoul, 03080, South Korea.
Seung Ha
SH
Oh
Department of Electrical and Computer Engineering, School of Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, South Korea.
Sung June
SJ
Kim
Department of Otorhinolaryngology-Head and Neck Surgery, Boramae Medical Center, Seoul Metropolitan Government-Seoul National University, 20 Boramae-ro 5-gil, Dongjak-gu, Seoul, 07061, South Korea. Electronic address: drpark@snu.ac.kr.
Min-Hyun
MH
Park
D000818:Animals; D019929:Cochlear Implantation; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D006168:Guinea Pigs; D006309:Hearing / Q000187:drug effects*; D008297:Male; D012405:Round Window, Ear / Q000187:drug effects* / Q000502:physiology*; D008063:Thioctic Acid / Q000008:administration & dosage / Q000494:pharmacology*
D008063:Thioctic Acid
Cochlear implantation; Hearing preservation; Lipoic acid; Residual hearing