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The Effect of Low-Level Laser Stimulation on Hearing Thresholds

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01820416
Recruitment Status : Terminated (Analysis showed no clinically or statistically significant effects)
First Posted : March 28, 2013
Results First Posted : June 1, 2017
Last Update Posted : June 1, 2017
GN Resound
Information provided by (Responsible Party):
Shawn Goodman, University of Iowa

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.

Condition or disease Intervention/treatment Phase
Hearing Loss Radiation: Low-level Laser Therapy Other: Placebo Comparator: Disabled Laser Not Applicable

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.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 35 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: The Effect of Low-Level Laser Stimulation on Hearing Thresholds
Study Start Date : September 2009
Actual Primary Completion Date : December 2009
Actual Study Completion Date : December 2009

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
Experimental: 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.
Radiation: Low-level Laser Therapy
Portable unit containing two laser diodes producing 532 and 635 nm wavelengths. Both diodes produced energy levels of 7.5 mw (class IIIb). Beams from both diodes were dispersed through lenses to create parallel line-generated beams, rather than spots. The 532 nm light was constant, and the 635 nm light was pulsed, with frequencies of 15 and 33 Hz. The pulsing alternated between frequencies every 30 seconds.
Other Name: Erchonia EHL laser (Erchonia Medical, Inc.)

Placebo Comparator: Disabled Laser
Low-level laser device with laser diodes disabled. Also applied for approximately 4 minutes to the area around the pinna, the back of the neck, and the top of the head.
Other: Placebo Comparator: Disabled Laser
Portable unit containing two DISABLED laser diodes. Same protocol was followed as for the Experimental (radiation) group, except that the disabled diodes produced no radiation.

No Intervention: Control
Visit laboratory using same schedule as experiment and placebo. No Low-level laser or any treatment applied. Used to assess normal test-retest variability.

Primary Outcome Measures :
  1. Change in Speech Perception [ Time Frame: 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.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 75 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • bilateral sensorineural hearing loss
  • normal middle ear status

Exclusion Criteria:

  • pregnant or lactating
  • serious mental health illness or medical/psychiatric hospitalization
  • treatment with cancer chemotherapeutic agents or aminoglycoside antibiotics
  • taking Aspirin, Ibuprofen, Naprosyn, Aleve
  • taking any Quinine-related drugs
  • taking any loop diuretics
  • have a developmental disability or cognitive impairment
  • history of drug abuse
  • involved in litigation or claim related to hearing loss
  • regularly exposed to significant occupational or recreational noise
  • have a photosensitivity disorder
  • have a retinal disease

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT01820416

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United States, Iowa
University of Iowa
Iowa City, Iowa, United States, 52242
Sponsors and Collaborators
University of Iowa
GN Resound
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Principal Investigator: Shawn S Goodman, PhD University of Iowa
Publications automatically indexed to this study by Identifier (NCT Number):
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Responsible Party: Shawn Goodman, Assistant Professor, University of Iowa Identifier: NCT01820416    
Other Study ID Numbers: 200808718
First Posted: March 28, 2013    Key Record Dates
Results First Posted: June 1, 2017
Last Update Posted: June 1, 2017
Last Verified: April 2017
Keywords provided by Shawn Goodman, University of Iowa:
Hearing Loss, Bilateral
Hearing Loss, Sensorineural
Additional relevant MeSH terms:
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Hearing Loss
Hearing Disorders
Ear Diseases
Otorhinolaryngologic Diseases
Sensation Disorders
Neurologic Manifestations
Nervous System Diseases