[Use of the round window micro cath for inner ear therapy - results of a placebo-controlled, prospective study on chronic tinnitus].
BACKGROUND
The local therapy of inner ear diseases provides a means of directly applying pharmacological substances and delivering electrical stimulation to inner ear structures. Problems relating to dosage, systemic effects and the blood-cochlear barrier are thus avoided, which is not the case with systemic therapy. The preferred access point is the membrane of the round window.


METHODS
An appropriately shaped catheter (DURECT Corporation, Cupertino, CA, USA), whose double-lumen passage system permits the variation of concentration and flow, is inserted into the round window niche. In a prospective, placebo-controlled clinical study, this application system was tested in 20 patients with chronic tinnitus. Following implantation the substances lidocaine, glutamate, glutamic acid and caroverine were applied via an attached external micropump.


RESULTS
The values for tinnitus loudness, level of irritation caused by the tinnitus and subjective effectiveness of the therapy - measured by means of the visual analog scale (VAS) - showed no significant change, although the most marked improvement was indicated for caroverine.


CONCLUSIONS
These results indicate that a positive effect was observable only in a proportion of the patients. Continuous therapy of tinnitus and inner ear diseases will only be possible once a totally implantable microdosage system has been developed.
Schwab
B
B
HNO-Klinik der Medizinischen Hochschule Hannover. schwab.burkard@mh-hannover.de
Lenarz
Th
T
Heermann
R
R
D000287:Administration, Topical; D000328:Adult; D000368:Aged; D001309:Auditory Threshold / Q000187:drug effects; D002408:Catheters, Indwelling; D002908:Chronic Disease; D007758:Ear, Inner / Q000187:drug effects*; D004724:Endoscopy; D005260:Female; D018698:Glutamic Acid / Q000008:administration & dosage*; D006801:Humans; D007260:Infusion Pumps; D008012:Lidocaine / Q000008:administration & dosage*; D008144:Loudness Perception / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement; D017060:Patient Satisfaction; D011810:Quinoxalines / Q000008:administration & dosage*; D012405:Round Window, Ear / Q000187:drug effects*; D014012:Tinnitus / Q000188:drug therapy*; D016896:Treatment Outcome
D011810:Quinoxalines; D018698:Glutamic Acid; D008012:Lidocaine; C000957:caroverine