The Effect of Low-Level Laser Stimulation on Hearing Thresholds

Not Applicable

Terminated

Brief Summary: The purpose of this study is to determine whether low-level laser therapy can improve hearing thresholds in individuals with hearing loss. Subjects will be randomly assigned to a treatment, placebo, or control group. The treatment group will be given a three treatment of low-level laser therapy, which consists of shining low-level lasers beams onto the ear and head. The laser beams are cool to the touch, and do not cause discomfort. Each laser treatment will last approximately 4 minutes. Three treatments will be applied three times within the course of one week. Hearing tests will be administered immediately before treatment, immediately after treatment, and six weeks after treatment. Results will be analyzed to determine the effect of the laser treatment on hearing.

Detailed Description: Low-level laser therapy has been practiced for about 20 years in Europe and is beginning to be practiced in the US. Theoretically, laser energy in the red and near infrared light spectrum is capable of penetrating 2-5 cm into tissue and can stimulate mitochondria in the cells to produce more energy (through the production of adenosine triphosphate), which in turn may help prevent or repair tissue damage. The effects of low-level laser therapy on hearing have not been well studied. It has been suggested that laser therapy might help repair damage to the cochlea and restore some degree of hearing loss. Studies of low-level laser stimulation of cochleae utilizing microscopy, PET imaging, and MRI suggest potential therapeutic benefit to hearing. While preliminary studies suggest a possible improvement in hearing thresholds, a carefully controlled study is needed to verify the results using a valid battery of audiological tests.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Arm && Interventions

Group	Intervention	Description
Low-Level Laser Therapy	Low-level Laser Therapy	Low-level laser applied for approximately 4 minutes to the area around the pinna, the back of the neck, and the top of the head.

Primary Outcome Measures

Name	Time	Method
Change in Speech Perception	7-10 days after baseline measures recorded	Hearing status, as assessed by the Connected Sentence Test (CST). Difference scores (post-test - pretest) are reported. The CST approximates everyday conversation. Scoring is based on the number of correctly repeated key words. Higher numbers indicate better scores. The minimum score is 0 (0%) and the maximum is 100 (100%). When comparing test-retest scores for an individual, Cox et al. (1988) suggest that changes of 15% or more (based on 100 key words) are indicative of significant changes. We subtracted the post-test from the pre-test, so that negative difference scores indicate worse performance, and positive difference scores indicate better performance. Difference scores with an absolute value smaller than 15 are interpreted as no significant change. In addition, pre- and post-test performance was assessed for groups using t-tests on the difference scores.

Secondary Outcome Measures