Discussion
hearing loss, acute hearing loss, Adverse drug reactions, SSHL
DEEP VEIN THROMBOSIS, RECRUITMENT, ADVERSE EVENT, THROMBOEMBOLISM, HEARING LOSS, PERIPHERAL ARTERIAL OCCLUSIVE DISEASE, ADVERSE DRUG REACTION
This randomized controlled trial on drug-induced defibrinogenation for SSHL did not demonstrate a significant difference between ancrod and placebo with respect to the primary outcome measure. Unfortunately, no conclusion regarding efficacy can be drawn, since the study was terminated ahead of schedule.The safety results show that ancrod was well tolerated. No serious adverse event was reported. Adverse drug reactions are within the expected range. Laboratory parameters show an expected decline in plasma fibrinogen in the ancrod group while remaining on a stable level in the placebo group. This observation supports ancrod’s mechanism of action and the dosing schedule. Ancrod was already marketed in Europe and Canada for indications like peripheral arterial occlusive disease, deep vein thrombosis, and prophylaxis for thromboembolism. It is easy to monitor by routine laboratory tests measuring plasma fibrinogen.The observed reduction of plasma fibrinogen by ancrod is in line with in vivo guinea pig studies, in which this drug-induced reduction of elevated fibrinogen levels resulted in an increase of cochlear blood flow accompanied by recovery of acute hearing loss [Drug-induced enzymatic defibrinogenation has the advantage of an easy, cost-effective, and widely accessible treatment. Previous studies investigated more elaborate extracorporeal techniques to prove the value of defibrinogenation in SSHL-treatment. A superior beneficial effect of fibrinogen/LDL-apheresis in comparison to the standard therapy of high-dose steroids was demonstrated in clinical studies [However, conducting and interpreting clinical studies on SSHL is challenging, especially under the terms of inherent high rates of spontaneous recovery. Rates of complete recovery range from 35 to 68% [The study was terminated early due to insufficient recruitment. This is probably caused by (1) demanding in-/exclusion criteria: After 5 years and eligibility screening of 620 patients with acute hearing loss, only 37 of the initially planned 99 patients were enrolled, of which 31 were randomized (5%). Furthermore, considering these highly selective criteria an adequate representation of “common” SSHL can be called into question. (2) Involvement of predominantly tertiary referral centers: The most frequently constituted exclusion criteria were “pretreated SSHL” (