Effects of gadolinium injected into the middle ear on the stria vascularis.
CONCLUSIONS
The concentration of gadolinium (Gd) used clinically showed no remarkable effects on the stria vascularis; however, a higher concentration had adverse effects. The concentration of Gd must be borne in mind when injecting Gd into the tympanic cavity.


OBJECTIVE
Endolymphatic hydrops has been visualized using high resolution MRI with the intratympanic administration of Gd in patients with Meniere's disease. We attempted to investigate the effects of Gd on the stria vascularis.


METHODS
Gd hydrate diluted eightfold with saline or non-diluted Gd or saline was injected into the tympanic cavity of guinea pigs. To investigate the effects of Gd on the stria vascularis, we measured endocochlear DC potential (EP) and observed the stria vascularis using transmission electron microscopy.


RESULTS
Intratympanic injections of Gd hydrate diluted eightfold with saline (1/8 Gd) and saline did not cause apparent changes in the EP. Moreover, the amplitude of the EP decreased significantly 60 min after non-diluted Gd was injected. Transmission electron micrographs of the stria vascularis revealed no significant morphological difference between the ears injected with 1/8 Gd and those injected with saline. There was significant morphological change in the ear injected with non-diluted Gd. The intercellular spaces were markedly enlarged.
Kakigi
Akinobu
A
Department of Otolaryngology, Kochi Medical School, Kochi, Japan. kakigia@kochia-u.ac.jp
Nishimura
Masahiko
M
Takeda
Taizo
T
Okada
Teruhiko
T
Murata
Yoriko
Y
Ogawa
Yasuhiro
Y
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004432:Ear, Middle; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage / Q000494:pharmacology*; D006168:Guinea Pigs; D007267:Injections; D008564:Membrane Potentials / Q000187:drug effects; D046529:Microscopy, Electron, Transmission; D013316:Stria Vascularis / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure
D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA