Last week we discussed a bit about marijuana legalization and its general effects.  For the effects of marijuana on  hearing, however, the jury is still out.

Probably due to the drug classification, there has been minimal study of marijuana and its effects on hearing, as well as on some other body functions.  The data available in 2017 are largely anecdotal and much of the hard research is yet to be funded and conducted. 

The National Institute on Drug Abuse (NIDA) (2015) indicates that a probable cause of the lack of research also stems from the Food and Drug Administration (FDA) requiring carefully conducted studies (known as clinical trials) in hundreds to thousands of human subjects to determine the benefits and risks of a possible medication. So far, researchers have not conducted enough large-scale clinical trials that demonstrate that the benefits of the marijuana plant (as opposed to its cannabinoid ingredients) outweigh its risks in patients it is meant to treat.

While there seems to be mostly anecdotal indications on the benefits or detriment of marijuana on hearing, there appear to be some logical indications as well as some seminal research that the drug might have some benefit for tinnitus.

 

New Thoughts of the Origin of Tinnitus

 

Until recently, not much was known about the cause or source of tinnitus. New thoughts on tinnitus from various researchers funded by the Veterans Administration (VA), National Institutes of Health (NIH) as well as private organizations such as the American Tinnitus Association (ATA), suggest that tinnitus is not necessarily an auditory or ear malady but a brain issue.

Prevailing older theories generally assume tinnitus is duee to inner ear malfunction of one type or another (e.g., mis-shapened or dstroyed hair cells;  lack of blood supply to the ear; etc). Yet, audiologists and otolaryngologists have known for some time that even when the auditory nerve is cut, the tinnitus from the “disconnected” ear can persist, often even worse than before.  

Dr. Thanos Tzounopoulos, Chair of Auditory Physiology within the Department of Otolaryngology at the University of Pittsburgh, was among the first researchers to suggest that the locus of tinnitus was in the brain and not the brain. His research suggests that tinnitus is likely caused by misfiring neurons in the auditory center of the brain, and may be caused by an imbalance between inhibitors and stimulus within the auditory sensation.

In other words, the brain is mistakenly responding to sound, where no sound exists, creating the tinnitus effect. These studies, begun in 2009, were further refined in 2011 and have become an ongoing investigation.

 

What does that have to do with marijuana use?

 

Naturally generated cannabinoids in the body are one of the inhibitors within the auditory center.   In 2011, Dr. Tzounopoulos and his team published research that demonstrated exaggerated activity in the brains of mice with tinnitus. They also made breakthroughs in the understanding of the endocannabinoid system, which was found to control aspects of brain plasticity. It is this activity that reacts to marijuana as these cannabinoids are present in the marijuana.

Dr. Tzounopoulos compares tinnitus to chronic pain and addiction, which also seem to involve plasticity in the brain and are treated with medical marijuana. While this does not shed light on the precise mechanism by which medical marijuana provides relief for tinnitus, it does show the components of the mechanism. 

Another recent theory of tinnitus is that it is a form of sensory epilepsy, sometimes arising from neuronal hyperactivity in the brainstem cochlear nucleus. The exact relation of tinnitus and seizure is not known but a few established facts can assist in the understanding how tinnitus and seizures might be connected. Of course, tinnitus is an auditory abnormality wherein a person hears ringing or buzzing sounds in the ear or head regions in the absence of any actual external sounds. Seizures are characterized by repeated movements of the body or body parts, sometimes violently. The intensity of both tinnitus as well as seizures can differ and present symptoms in varying degrees of intensity.  Both the conditions of tinnitus and seizures occur because of an irregularity of the electrical activities in the brain. This irregularity is usually caused by a nervous system disorder or a pathological condition in the neck and head regions. There are other causes as well that can contribute to the occurrence of both these conditions. Since the causes vary widely in both disorders sometimes the exact reason for tinnitus and seizure is difficult to pin point. At the same time, since most of the causal factors usually rise from similar root causes in many instances, it is possible that tinnitus and seizures can indicate a common origin – though they need not always coincide.  Increasing evidence suggests that cannabinoid drugs can also have antiepileptic effects.  And since the origins of both tinnitus and seizures are thought to be similar, then the possibility that cannabinoids could be beneficial holds some promise.

Of course, medicinal cannabis has been prescribed to help people cope with some of the conditions that can cause tinnitus. In those cases, it’s easy to see how marijuana might help. Even among those people whose tinnitus doesn’t respond to marijuana, it may help alleviate some of the stress, anxiety, and insomnia that plague tinnitus sufferers. 

One thing many people forget is that a marijuana prescription isn’t like a regular pharmaceutical prescription–it is essentially permission for an individual to experiment with medical-grade cannabis and determine if it helps their symptoms. Some tinnitus sufferers may find that it does, while others may find that it worsens them.   While there is no recommendation for the use of marijuana for tinnitus or hearing loss cited in the literature, it is extremely likely that new research studies will be conducted now that marijuana is legal in 7 states with more to come in the future.

 

References:

Eye and Ear of Pittsburgh (2017). Tinnitus and auditory science.  Retrieved January 9, 2017.

Marijuana Doctors (2013). Medical marijuana and tinnitus.  Retrieved January 9, 2017.

Middleton JW, Kiritani T, Pedersen C, Turner J, Gordon M, Shepherd G, Tzounopoulos T. (2011). Mice with behavioral evidence of tinnitus exhibit dorsal cochlear nucleus hyperactivity due to decreased GABAergic inhibition. Proc Natl Acad Sci U S A 108(18). Retrieved January 10, 2017.

MedicalMarijuanablog.com (2016). Marijuana a solution to tinnitus.  Retrieved January 9, 2017.

National institute on Drug Abuse (2015). Is marijuana medicine?  Drug Facts.  Retrieved January 10, 2017.

Tuneouttinnitus.org (2017). A neurological tinnitus study.  Retrieved January 9, 2017.

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