Effect of intratympanic dimethyl sulphoxide (DMSO) in an in vivo model of cisplatin-related ototoxicity.

Although dimethyl sulfoxide (DMSO) is one of the most common solvents employed in otoprotection studies, its effect on the inner ear remains unknown. Only a few in vitro studies have addressed the effect of DMSO in cochlear cells. Up to the date, no in vivo functional studies have been reported. To determine the effect of intratympanic DMSO application in the inner ear, and to evaluate its effect in combination with cisplatin in Wistar rats, twelve Wistar rats were randomly assigned into two groups. Group A received intratympanic 1 % DMSO in both ears. Group B received intraperitoneal cisplatin (10 mg/kg) and intratympanic 0.5 % DMSO in the right ear and saline solution in the left ear. Functional changes were evaluated with Auditory Steady-State Responses before and 5 days after the procedure. Morphological changes were studied by means of confocal laser scanning microscopy following the removal of the temporal bones and cochlear dissection. Hearing threshold levels in group A did not show any statistically significant changes after the treatment. In group B, significant differences between pre- and post-treatment were found, with no statistically significant variations between right (DMSO) and left ear (saline solution). We suggest that DMSO could be safely used to dissolve hydrophobic compounds in otoprotection studies without interfering with the cochlear damage produced by cisplatin.