INTRODUCTION

There is a variety of medical and non-medical therapies in practice, which were not evaluated regarding its effectiveness by any systematic evidence oriented investigation. A number of therapies of medical and non-medical type try to treat the different types of tinnitus. The evidence in the scientific literature also had to be cleared in the field of diagnosis and classification as well as medical/psychiatric/psychological procedures of existing medical therapy.

QUESTION

The HTA report had to investigate the following questions: Which evidence do diagnostic methods in recognition of tinnitus have? Which types of therapy show medical effectiveness at the acute or chronic tinnitus without an organic cause? Which consequences (need for further research, future procedures) can be drawn?

METHODOLOGY

In the following databases "tinnitus" was searched according to the search string: HTA97; INAHTA; CDAR94; CDSR93; CCTR93; ME66; ME0A; HT83; SM78; CA66; CB85; BA70; BA93; EM74; IS74; ET80; EB94; IA70; AZ72; CV72; GE79; EU93; HN69; ED93; EA08

RESULT

1932 studies, unsorted after assessment in accordance with EBM criterions, selection: 409 studies. Due to the completely heterogeneous representation modes of the therapeutic approaches at the treatment of the chronic tinnitus no quantitative synthesis method could be performed. Therefore the methodology of a qualitative overview has been carried out.

RESULTS

The diagnostic confirmation of the non-specific tinnitus without organic cause meets with the problem of the assurance of the diagnosis tinnitus. According to the current opinion the stepwise diagnostics is carried out also in the case of the so called subjective tinnitus. Nothing can be said about the evidence of these procedures since no publication was found about that. A study concerning the evidence of the diagnostic questionnaires from Goebel and Hiller [1] comes to the end that the tinnitus questionnaire frequently used (TF) [2] is the best evaluated procedure. The number of therapies which treat tinnitus is exceptionally high and makes clear, that the search for "the" tinnitus therapy is still going on. According to the current knowledge tinnitus genesis is multifactorial and therefore there can't be any standard therapy for tinnitus. The following seven categories can be distinguished: AD 1: MACHINE-AIDED ACOUSTIC THERAPIES From many studies regarding machine-aided acoustic therapy of tinnitus only two showed an evidence degree that allows scientifically correct statements about the effectiveness of these procedures. Selectively significant improvements could be shown in the comparison with a placebo (apparatus switched off) a superiority of tinnitus-maskers. AD 2: ELECTROSTIMULATION In an application study of electro-stimulation the results were not evaluated statistically, but it was described descriptively that a successful medical treatment can be expected in about 50% of the cases. AD 3: PSYCHOLOGICAL THERAPY PROCEDURES Hypnosis did not show positive effectiveness. With regard to biofeedback it can be concluded that this method can be effective in individual cases, however regarded as unreliable from missing reproducibility. Neurobiofeedback could prove that it had a positive therapeutic effect. From eight controlled studies to relaxation techniques and cognitive behaviour therapy four studies showed a therapeutic effectiveness and four failed. Combined therapies proved generally to be more effective than individual types. The behaviour medical psychotherapy could show a positive therapy effect. In a study with cognitive therapy and relaxation (three groups, a passive relaxation, an active relaxation and a cognitive therapy) short-term successes could be stated (for one month), however, the parameters of success returned on the initial value after four months. Also only coincidental and short-term successes could be achieved with cognitive behaviour therapy training, autogenic training and structured group psychotherapy. AD 4: TINNITUS RETRAINING THERAPY (TRT) Unfortunately, the published results of the TRT are methodically frequently bad and scientific of a poor value. Many of the studies presented until now regarding tinnitus retraining therapy are not informative in their scientific context. In a study with 95 patients with a chronic tinnitus TRT could show a significant, more than six months lasting stable success by comparison to a combination of TET with group behaviour therapy (improvement be achieved around at least ten points in the tinnitus questionnaire (TF)). AD 5: PHARMACOLOGICAL THERAPIES Rheological drugs (medicines for hemodilution) could not show any statistically significant effect in the treatment of tinnitus. Studies to the medical treatment with tocainides (lidocaine) showed repeatable positive effects on tinnitus in higher dosages (as of 1.2 mg/day). Lamotrigine as a medicine had an effect positively only at with a small fraction of patients. Two studies with GABA receptor agonists could not prove therapeutic effects for tinnitus. Undesired side-effects were observed. Injections with Carvoverine (a glutamate antagonist) achieved significantly successes with a special form of tinnitus, the "Cochlear-synaptic tinnitus (CST)". A tricyclic antidepressant (Amitriptilin) could prove superiority against placebo. This effect could be confirmed in another study. However Clonazepame (a benzodiazepine), could not achieve any improvement. Short-term improvements were achieved with other benzodiazepines (Clonazepame, Diazepam, Flurazepame, Oxacepame and Alprazolame). A German retrospective study suggests a graded pharmacological therapy by means of rheological infusion therapy, applications of neurotransmitters, and injections of lidocaine. This method achieved a disappearance or a recovery of the complaints at 95.3% of the acute and 26.7% of the chronic cases. AD 6: SURGICAL PROCEDURES The effects of the operative excision of the stapes (stapedectomy) showed significant effects concerning tinnitus. This method is a routine operation to recover hearing, effects on tinnitus were observed only coincidently. There are generally high frequencies of improvements of tinnitus after cochlea implantations; however the risk of deterioration is present with this method. AD 7: OTHER AND ALTERNATIVE THERAPY PROCEDURES The hyperbaric oxygen therapy can be considered successful after acute events with tinnitus. The therapy should be started in the first month after appearance of the tinnitus. The methods transcranial-, electromagnetic and transcutaneous nerve stimulations did not show any significant effects on tinnitus. Also low laser medical treatment showed disappointing effects. The "pneumatic external contra-pulsation" is described as an unproblematic usable procedure by the authors of the examination, but 10% of the patients had to stop the medical treatment because of complications associated with the medical treatment. Acupuncture showed significant improvements in comparison to medical treatment. The effectiveness of this therapy could not be reproduced in another study. Five other studies between 1993 and 1999 also did not show any therapeutic effect of this method. Gingko-Biloba preparations did not show any positive effects in large-scale studies on tinnitus.

DISCUSSION

Neither the diagnostic procedures nor the therapeutic methods or the individual therapies reach a usual scientific level in medicine. Unsolved problems concerning insurance, economic as well as legal problems have resulted for the patients and for caring stuff from this unsatisfactory situation. Numerous competitive tinnitus emergence models led to an incredible creativity in trying out different therapy approaches. No convergence of the therapy procedures can be seen within the last decades of tinnitus research, contrariwise there is always more and more "creativity" of new approaches. Priority has to be given to find the cause of tinnitus since therapies are a consequence of a better understanding of these symptoms that evidence oriented investigations on an usual scientific level can be started.

CONCLUSION

The innumerable therapeutic approaches, seeming completely incoherent to their effects should be coordinated on the meaningfulness, on the success parameters and with patient safety in light of the most plausible explanation models for non-specific chronic Tinnitus. To this the facilities of competence centres or related science- directing facilities are recommendable. Examinations which are carried out also with small numbers show often methodical insufficiencies. It is necessary that minimal requirements on a scientifically clinical experiment, such as design, case number calculation, analytic statistics, control group, are fulfilled. It is recommendable, that further research has to be promoted regarding tinnitus causes that a coordinated evidence-orientated treatment will be developed.