Research shows that approximately 43% of individuals who have sustained a concussion experience light sensitivity and 50% experience sound sensitivity. Sound sensitivity, also known as phonophobia and light sensitivity, which is alternatively known as photophobia, are two of the primary physical symptoms in post-concussive patients.  

The discomfort and pain experienced with phonophobia and photophobia, often results in the disruption of everyday life. Being in a strongly lit area, in the midst of commotion, or even checking the screen of your electronic devices may begin to cause distress. Those experiencing these post-concussive symptoms are encouraged to refrain from using electronic devices or exposing themselves to lighting or sounds that may be perceived as intrusive. However, in some cases, even when the aversive stimuli are removed, the discomfort may persist.

Phonophobia:

Sound sensitivity encompasses a wide range of unpleasant reactions to sound; it may entail a reduced tolerance to sound or general discomfort in response to noise. Many individuals find themselves reclassifying sounds of moderate intensity, as overtly loud and intrusive. 

In post-concussion evaluations, sound sensitivity is typically assessed through a single question. Consequently, phonophobia is frequently overlooked in clinical and laboratory settings. A recent study of post-concussive athletes, revealed that individuals who previously had normal sound detection thresholds, developed a heightened level of discomfort and reduced tolerance for standard audiometric frequencies. 

Photophobia:

Photophobia is one of the most common visual complaints, post-concussion; any exposure to light may induce or aggravate pain. Patients typically feel the fervent effects of photophobia 7-19 days following a concussion. However, there are instances where individuals retain their heightened sensitivity to light for a prolonged period of time.

Sunglasses are routinely used to mitigate the impact of light. The utility of traditional dark sunglasses only goes so far, as they diminish all frequencies of light and are therefore unhelpful in many settings. Studies have begun to analyze the efficacy of coloured glasses in treating photophobia. One particular study found that coloured glasses provided relief from the effects of photophobia; 85% of patients benefited from the use of blue-, green-, red- and purple-coloured glasses. Further research is needed to determine the best way to alleviate the light induced sensitivity and pain.

Are Phonophobia and Photophobia connected?

One study conducted on concussed athletes, found that 80% of the athletes self-reported light sensitivity in addition to sound sensitivity. This association of symptoms can be attributed to the fact that sensitivity to sound and sensitivity to light may have overlapping mechanisms. Both phonophobia and photophobia involve increased neural activity and/or excitatory-inhibitory imbalances in the primary sensory cortices during instances of high stimulation. 

Main Take-Away Message:

Post-concussion sound and light sensitivity are very common. If you are experiencing these symptoms, make sure to lessen your exposure to either stimuli and communicate with a healthcare professional. While the occurrence of phonophobia and photophobia in post-concussive states is well established, researchers are still in the process of investigating and developing tools to aid these disturbances. 

Written by Anne Mburu

References:

Clark, J., Hasselfeld, K., Bigsby, K., & Divine, J. (2017). Colored Glasses to Mitigate Photophobia Symptoms Posttraumatic Brain Injury. Journal of athletic training, 52(8), 725–729. https://doi.org/10.4085/1062-6050-52.4.04

Assi, H., Moore, R. D., Ellemberg, D., & Hébert, S. (2018). Sensitivity to sounds in sport-related concussed athletes: a new clinical presentation of hyperacusis. Scientific reports, 8(1), 9921. https://doi.org/10.1038/s41598-018-28312-1

Digre, K. B., & Brennan, K. C. (2012). Shedding light on photophobia. Journal of neuro-ophthalmology: the official journal of the North American Neuro-Ophthalmology Society, 32(1), 68–81. https://doi.org/10.1097/WNO.0b013e3182474548

Richman, E. A., Dr. (2014). Traumatic Brain Injury and Visual Disorders: What Every Ophthalmologist Should Know. Retrieved December 6, 2020, from https://healthcare.utah.edu/fad/mddetail.php?physicianID=u0030373