Mechanism and Protection of Radiotherapy Induced Sensorineural Hearing Loss for Head and Neck Cancer

Table 1

Studies on the protective effect of antioxidants on various SNHL.

Drug	Experimental design	Outcome	Mechanism	Reference
MT	Animal experiment: rats	DPOAE: M+RT group and RT+M group>RT group	Inhibit production of ROS7; enhance the DNA repair process	[89]
AMF	Animal experiment: guinea pigs	Degree of cochlear hair cell damage: IRR + AMF group < RT group.; No difference between 100 mg/kg and 200 mg/kg AMF groups	Be hydrolyzed into active component in vivo, which has sulfhydryl group that scavenges free radicals	[90]
LC	Animal experiment: guinea pigs	Histopathological examination: LC can ameliorate radiation-induced cochlear damage in guinea pigs.	Improving mitochondrial oxygen utilization and scavenging free-radicals	[91]
MP	Clinical trials: NPC patients	Pure tone audiometry; DPOAE; ABR: the use of MP during RT can reduce the early RISNHL	Mechanisms to protect the OHC: 1. Affects transcription and inhibits caspase-mediated apoptosis; 2. Inhibits inflammatory response; 3. Promotes GSH synthesis	[92]
PIR	Animal experiment: male albino guinea pigs	Histopathologic examination: PIR might reduce radiation-induced cochlear damage in guinea pigs	Increases oxygenation in the tumor cells with its rheological effects and decreases apoptosis in surrounding healthy cells	[93]
EC	Cell experiment: HEI-OC1 and UB-OC1; Animal experiment: embryos/rats	EC can increase the survival rate of HEI-OC1 cells after radiotherapy.; EC can inhibit the ABR threshold in the rats.	Inhibits ROS production and MAPK activity	[94]

MT: melatonin; AMF: amifostine; LC: L-carnitine; MP: methylprednisolone; PIR: piracetam; EC: epicatechin; GSH: glutathione.