A Phase III Trial of Magnesium Dependent Tinnitus

Descriptions of tinnitus date back to the time of ancient Egypt, yet science has failed to unravel the mysterious underlying mechanisms that produce these subjective auditory perceptions of sound. These perceptions may be manifestations of damage resulting from noise exposure, ototoxicity, or other abnormal conditions of the auditory system. However, many individuals have idiopathic tinnitus for which no specific cause can be determined. Although often presenting in conjunction with hearing loss, the magnitude of hearing loss does not necessarily correspond with the severity of tinnitus. In addition, some individuals reporting tinnitus experience concomitant hyperacusis. This relationship suggests these processes may be linked by underlying imbalances at the level of the hair cell. The possible influence of magnesium (Mg) and its antagonist, calcium, has been discussed in the literature as a contributing factor in the mitigation of noise-induced hearing loss, ototoxicity, and the hyperexcitability of the auditory system. Permanent and temporary changes in auditory function have been linked to nutritional deficiencies of magnesium. Mg deficiency has resulted in increased susceptibility to noise-induced hearing loss, ototoxicity, and hyperexcitability of the auditory system. The recommended daily allowance (RDA) for Mg in adults is 4.5 mg/kg; however, all age groups of Americans fall short of the RDA for Mg by 100 mg daily. This lack of appropriate magnesium intake may have negative consequences. For example, the putative Mg mechanism within the auditory system involves a metabolic cellular cascade of events. Specifically, Mg deficiency leads to increased permeability of the calcium channel in the hair cells with a consequent over-influx of calcium, an increased release of glutamate via exocytosis, and overstimulation of N-methyl-D-aspartate receptors on the auditory nerve fibers. Recent studies of both noise-induced hearing loss and idiopathic sensorineural hearing loss have suggested that Mg supplementation may lessen the severity of tinnitus in patients. Mg improved hearing recovery and lessened tinnitus in patients with idiopathic sudden hearing loss. More recently, a well-controlled study that Mg was a relatively safe and convenient adjunct to corticosteroid treatment for enhancing the improvements of hearing in acute-onset sensorineural hearing loss at a dose of 4 g. The protective effect of Mg in noise-induced hearing loss has been previously reported. Despite these encouraging findings, no controlled study has examined the effect of Mg supplementation for subjects with moderate to severe tinnitus. In this study subjects made 4 visits to the clinic over about 2 months. At the first visit, subjects had a hearing test. Prior to beginning each round of supplements, subjects were asked to rate the severity of their tinnitus on a 1-10 scale, and to complete the Tinnitus Handicap Inventory (THI) questionnaire. Subjects were then randomized to 1 of 2 groups. One group began with 532 mg of Mg for 25 days, the other group began with a placebo supplement for 25 days. At visit 2, the subjects had a hearing test, rated their tinnitus, and completed the THI questionnaire as well as the Treatment Period Survey. Subjects did not take any supplement for 2 weeks, then returned for visit 3. At Visit 3, the subjects had a hearing test, rated their tinnitus, and completed the THI questionnaire they then took the opposite supplement (placebo or Mg) for 25 days. At Visit 4, the subjects had a hearing test, rated their tinnitus, and completed the THI questionnaire as well as the Treatment Period Survey.