Ketamine's Effects on Tinnitus
Ketamine can potentially worsen tinnitus as a side effect, particularly when administered intravenously for pain management. 1 The evidence specifically identifies tinnitus as a possible adverse effect of intravenous lidocaine administration, and while ketamine's relationship to tinnitus is less directly documented, it operates through glutamate pathways that may influence auditory perception.
Mechanism and Evidence
Ketamine is a noncompetitive N-methyl D-aspartate (NMDA) receptor antagonist that blocks glutamate 1. This mechanism is relevant to tinnitus because:
- Tinnitus is often compared to neurologic pain, and both conditions involve similar neural pathways 2
- Glutamate excitotoxicity in the cochlea has been implicated in some forms of tinnitus 3
- NMDA receptor antagonists like ketamine can affect central nervous system function in ways that might influence auditory processing
Clinical Context
The NCCN guidelines note that ketamine is primarily used at sub-anesthetic doses for:
- Management of cancer pain that is refractory to other treatments
- Potential improvement in mood for individuals with depressive disorders 1
However, the guidelines do not specifically address ketamine's effects on tinnitus.
Risk Factors and Considerations
When considering ketamine use in patients with tinnitus or at risk for developing tinnitus:
- Route of administration matters: Intravenous administration may pose higher risks for side effects including potential auditory disturbances 1, 4
- Dose-dependent effects: Ketamine is typically administered at 0.5 mg/kg, but doses range from 0.1-0.75 mg/kg depending on individual response 4
- Duration of treatment: While most studies focus on short-term use, extended ketamine treatment might have different implications for auditory function 4
Related Evidence on Drug-Induced Tinnitus
It's important to note that over 130 drugs and chemicals have been reported to be potentially ototoxic 5. While ketamine is not specifically listed among the major classes of ototoxic drugs (aminoglycosides, anti-inflammatory agents, diuretics, antimalarial drugs, antineoplastic agents), its effects on glutamate pathways could theoretically influence auditory perception.
Clinical Implications
For patients with pre-existing tinnitus or at risk for developing it:
- Monitor for changes in tinnitus symptoms if ketamine is administered
- Consider alternative analgesics or antidepressants if a patient reports worsening tinnitus with ketamine
- Be aware that ketamine can cause various sensory disturbances, including auditory effects, as part of its dissociative properties 1
Ketamine's Other Side Effects
When considering ketamine use, be aware of other potential side effects:
- Emergence reactions (floating sensations, vivid dreams, hallucinations, delirium) in 10-30% of adults 1
- Cardiovascular effects: dose-dependent increases in heart rate, blood pressure, and cardiac output 1
- Recovery agitation, particularly in patients with higher ASA status 1
While ketamine has shown promise as a rapid-acting treatment for depression 1, 6 and refractory pain 1, its effects on sensory perception, including potential impacts on tinnitus, warrant careful consideration in clinical decision-making.