The onset of Sudden Sensorineural Hearing Loss (SSNHL) can be a frightening experience. Since it is unpredictable and develops rapidly, it is especially alarming. Most incidents of SSNHL develop within three days and are usually unilateral – affecting only one ear. Individuals may wake up to discover hearing loss, or they may notice it occurring over the course of several days. Sudden sensorineural hearing loss is defined as a hearing impairment of at least 30 dB in three sequential frequencies.
Vascular occlusion and hearing
While medical practitioners can’t say definitively what provokes an episode of SSNHL, sometimes the vascular system seems to play a role. Besides vascular occlusion, other causes may include:
- Viral and bacterial infections
- Ruptured inner ear membranes
- Tumors
- Autoimmune diseases
Researchers have focused on understanding the role that the vascular system plays in sudden hearing loss, including strokes. A stroke is brain damage that results from an obstruction in its blood supply. A stroke that occurs in the outer part of the brain stem can impact hearing.
Risk of Stroke Development among SSNHL Patients
Published in 2008 in Stroke, a study based in Taiwan sought to determine whether there was a link between SSNHL episodes and an increased risk of stroke. The study, conducted by Herng-Ching Lin, Pin-Zhir Chao and Hsin-Chien Lee, evaluated 7,115 patients over the course of five years after hospitalization. Of these 7,115 patients, 1,423 of them were hospitalized right after sudden hearing loss. The researchers used the remaining 5,692 appendectomy patients as a control group.
At the conclusion of the five-year study, 621 patients of the entire sample population had experienced a stroke – 180 of whom were SSNHL patients. After the researchers adjusted for gender, income, medical background and other relevant factors, the data indicated that the hazard for having a stroke was 1.64 times greater – more than a 150% increased chance – for SSNHL patients than the control group appendectomy patients. For the first time this study demonstrated that sudden hearing loss may serve as an early warning sign for a stroke.
What Should Patients who have Experienced Sudden Hearing Loss do Next?
Since approximately 40 – 65% of SSNHL cases result in spontaneous recovery, there is hope. However, anyone who has experienced sudden hearing loss should monitor their health and look for signs of impending stroke. According to the 2008 study, the average time between initial SSNHL hospitalization and the onset of stroke was 804 days. Most strokes occurred within the first two years.
After you or a loved one has experienced sudden hearing loss, it’s important to undergo a comprehensive neurological exam and schedule routine follow-ups, even years after the initial event. For more information on hearing and audiological effects of stroke, make an appointment for our free hearing assessment*.