Nitrous Oxide Treatment for Tinnitus
Condition: Tinnitus
MeSH terms: Tinnitus
Intervention: Nitrous oxide gas for inhalation; Placebo gas for inhalation
Intervention description: Nitrous oxide gaseous mixture (50% nitrous oxide and 50% oxygen) for 40 minutes duration under anesthesia supervision with monitoring according to standards set by the American Society of Anesthesiologists.; Placebo gaseous mixture (50% nitrogen and 50% oxygen) for 40 minutes duration under anesthesia supervision with monitoring according to standards set by the American Society of Anesthesiologists.
Intervention MeSH terms: Nitrous Oxide
Phase: Phase 4
Study type: Interventional
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Enrollment: 40.0
Sex: All
Minimum age: 18 Years
Maximum age: 65 Years
Healthy volunteers: Accepts Healthy Volunteers
Keywords: Nitrous Oxide

Summary:

      Tinnitus is perception of sound without the presence of an external acoustic stimulus.
      Approximately 50 million Americans experience chronic tinnitus and of these, 10 million have
      bothersome tinnitus. The tinnitus research literature suggests that NMDA receptor antagonists
      may prove to be useful in reducing tinnitus. Nitrous oxide, a member of the NMDA receptor
      antagonist class, is a widely-used general anesthetic and sedative with a proven safety
      profile. The investigators hypothesized that the administration of nitrous oxide, an NMDA
      receptor antagonist, may be effective in treatment of tinnitus. The study design was a
      randomized placebo-controlled crossover trial.
    

Eligibility criteria:

        Inclusion Criteria:

          -  Adult men and women 18-65 years of age

          -  Subjective, unilateral or bilateral, non-pulsatile tinnitus scoring "Bothered more
             than a little but not a lot", "Bothered a lot", or "Extremely bothered" on the Global
             Bothersome scale

          -  Able to give informed consent

          -  Must be able to read, write, and understand English

        Exclusion Criteria:

          -  Bipolar disorder

          -  Schizophrenia

          -  Schizoaffective disorder

          -  Substance abuse or dependence (except for remote substance abuse or dependence with
             remission at least 1 year prior to the study and except for nicotine use disorders)

          -  Acute medical illness that may pose subject at risk during nitrous oxide
             administration

          -  Active psychotic symptoms

          -  Patients with significant pulmonary disease and/or requiring supplemental oxygen

          -  Contraindication against the use of nitrous oxide:

          -  Pneumothorax

          -  Bowel obstruction

          -  Middle ear occlusion

          -  Elevated intracranial pressure

          -  Chronic cobalamin and/or folate deficiency treated with folic acid or vitamin B12

          -  Pregnant patients

          -  Breastfeeding women

          -  Previous administration of NMDA-receptor antagonists (e.g., ketamine) within the last
             3 months

          -  Tinnitus related to cochlear implantation, retrocochlear lesion, Meniere's Disease, or
             other known anatomic lesions of the ear or temporal bone

          -  Tinnitus related to a Workman's Compensation claim or litigation-related event that is
             still pending.

          -  Any medical condition, which, in the opinion of the PI, confounds study results or
             places the subject at greater risk