An fMRI Investigation of the Effects of IV Lidocaine on Tinnitus

A total of 40 subjects will be enrolled in this study. Ten study volunteers will be enrolled in each of the following four groups:

• - Normal hearing (NH) without tinnitus (T-)
• - Normal hearing (NH) with tinnitus (T+)
• - Unilateral hearing loss (uHL) and ipsilateral unilateral tinnitus (uT+)
• - Bilateral hearing loss (bHL) and bilateral tinnitus (bT+)

Application of the study treatment may occur at the initial Screening Visit (pending all eligibility requirements can be confirmed) or at Visit 1. The first visit (not including IV lidocaine infusion) should take no more than 3 hours. The investigators will assess patient eligibility and obtain a baseline MRI, audiometry with high frequency, and middle ear muscle reflexes. Three questionnaires (THI, TFI, VAS) will also be given prior to IV lidocaine infusion to assess patients' perception of their tinnitus.

The patient visit and baseline screening may take up to 8 hours total. Patients may have completed the screening/baseline visit on a prior day, in which case the visit should take no more than 5 hours. At the screening/baseline visit, patient will be asked to complete three questionnaires; have an audiogram with high frequency and middle ear reflexes; a pregnancy test if the patient is a woman of childbearing age, and a baseline MRI to assess brain activity. We will also obtain a baseline EKG to evaluate the patient's heart and blood draw to check liver and kidney function. At the infusion visit, patients will receive IV lidocaine infusion for 30 minutes (500mg maximal dose) and an fMRI of the brain. After the infusion, the investigators will draw some blood samples to test for serum lidocaine levels, perform another audiogram with high frequency and middle ear reflexes, and administer the same three questionnaires (THI, TFI, VAS). The investigators will follow-up with patients via email 30 (±7) days after the infusion visit for any adverse event and ask them to complete the three questionnaires (THI, TFI, VAS).

Inclusion criteria

-Age ≥ 18

• Ability to provide informed consent
• English speaker
• Falls under one of the four groups a. Normal Hearing without Tinnitus (NH/T-) i. Normal Hearing as defined as pure tone thresholds of 25 dB or less across all tested frequencies ii. Subjective confirmation of lack of tinnitus* 1. Never or rarely b. Normal Hearing with Tinnitus (NH/T+) i. Normal Hearing Normal Hearing as defined as pure tone thresholds of 25 dB or less across all tested frequencies ii. Subjective confirmation of tinnitus* 1. Often, always c. Unilateral hearing loss and ipsilateral unilateral tinnitus (uHL/uT+) i. Unilateral hearing loss as defined by pure tone thresholds of 50 dB or greater across 3 frequencies in the bad ear and 25 dB or less in good ear ii. Subjective confirmation of tinnitus in the good ear* 1. Often, always d. Bilateral hearing loss and bilateral tinnitus (bHL/bT+) i. Bilateral hearing loss as defined by pure tone thresholds of 50 dB or greater across 3 frequencies in both ears ii. Subjective confirmation of tinnitus in both ears*

• Often, always

• Tinnitus will be confirmed via Likert-scale: Never - Rarely - Sometimes - Often - Always

Exclusion criteria

• Currently undergoing tinnitus treatment with other pharmacologic agents

a. Patients may be eligible if they complete a 60 day washout period from pharmacologic agents treating tinnitus

• Inability to tolerate fMRI or other contraindications of fMRI including claustrophobia or presence of ferromagnetic objects in the body that cannot be removed.
• Contraindications to IV lidocaine administration such known allergy to lidocaine
• History of myocardial infarction or cardiac arrhythmias including Wolff-Parkinson-White, severe sinoatrial, atrioventricular or intraventricular heart block in the absence of a pacemaker
• History of seizure disorder
• Resting BP of <100/50
• Currently taking antiarrhythmics
• Have taken antibiotics within 48 hours of infusion
• Known hepatic failure
• Pregnant or lactating women
• Patient with other neurological or psychiatric disorders, such as stroke, brain tumor, schizophrenia, bipolar disorder.
• Patients who cannot fill out the questionnaires