Yes, a stroke can cause hearing loss in one ear. This sudden, one-sided hearing loss is often the result of a disruption in the blood supply to the delicate structures of the inner ear or the auditory centers in the brain. A stroke occurs when blood flow to a part of the brain is blocked by a clot or a ruptured blood vessel, causing brain cells to die quickly from lack of oxygen and nutrients.
The sudden onset of hearing loss caused by a stroke is medically classified as Sudden Sensorineural Hearing Loss (SSNHL). This condition typically affects only one ear, which is why it is often the first symptom of a stroke affecting the posterior circulation of the brain. Immediate medical evaluation is necessary to distinguish a stroke from other, less serious causes of SSNHL.
The Vascular Connection: How Stroke Disrupts Auditory Function
The inner ear, which houses the cochlea for hearing and the vestibular labyrinth for balance, has a vulnerable blood supply. This entire system is fed by a single vessel known as the internal auditory artery. This artery is an “end artery,” meaning it has very few collateral connections to provide backup blood flow if it becomes blocked.
The internal auditory artery usually branches off the anterior inferior cerebellar artery (AICA), which is a part of the posterior circulation system that supplies the brainstem and cerebellum. A blockage in the AICA or its branch immediately starves the inner ear of oxygen. This lack of oxygen causes the sensory hair cells in the cochlea to die, resulting in a sudden and profound hearing loss in the corresponding ear.
When the stroke affects the AICA, it often damages both the hearing organ (cochlea) and the balance organ (vestibular labyrinth), which are supplied by the same artery. This often results in a combination of sudden hearing loss and acute vertigo. Strokes that cause hearing loss can be categorized as peripheral, due to damage to the inner ear itself, or central, due to damage to the auditory processing nuclei located in the brainstem.
A central stroke affecting the brainstem or cerebellum can disrupt the brain’s ability to process sound, even if the inner ear is healthy. This type of damage may not cause a measurable pure-tone hearing loss but can lead to difficulties in understanding speech, especially in noisy environments, a condition known as auditory processing disorder. Whether the hearing loss is peripheral or central, the root cause is a vascular blockage interrupting blood flow to these specialized structures.
Clinical Identification of Stroke-Induced Hearing Loss
Physicians must quickly determine if a sudden, one-sided hearing loss is an isolated inner ear problem or a sign of an underlying stroke. While many cases of SSNHL are idiopathic, or of unknown cause, the presence of specific accompanying symptoms strongly suggests a stroke. These “red flag” symptoms include:
- A sudden onset of vertigo that lasts for days
- Loss of coordination
- Difficulty walking
- New-onset motor weakness or numbness on the face or body
A comprehensive hearing test, known as audiometry, is performed to characterize the degree and type of hearing loss. Further specialized testing, such as vestibular assessments, can confirm whether the balance system is also affected, which is common in stroke-related cases. The standard for confirming a stroke in the auditory pathway is specialized medical imaging, specifically a Magnetic Resonance Imaging (MRI) scan.
An MRI is used to visualize the brainstem and cerebellum, looking for signs of a recent stroke, often appearing as a bright spot on a Diffusion-Weighted Imaging (DWI) sequence. Advanced MRI techniques, such as post-contrast 3D-FLAIR, can also detect subtle swelling or abnormal enhancement in the inner ear itself, pointing to a labyrinthine infarction caused by a vascular blockage. The presence of a stroke lesion on the MRI confirms the hearing loss is of vascular origin and requires immediate stroke management.
Recovery and Management Options
The prognosis for recovering hearing after a stroke is highly variable and depends on the size and exact location of the stroke. Studies tracking patients with stroke-related hearing loss have shown that approximately 65% experience some degree of partial or complete hearing recovery over time. Prognosis tends to be poorer for individuals who experience profound hearing loss at the onset or who have multiple preexisting vascular risk factors.
For those who do not recover their hearing, various management options exist to improve communication and quality of life. Standard hearing aids may be used if there is residual hearing, but when one ear has poor or no hearing, specialized devices are necessary. The Contralateral Routing of Signal (CROS) system is a common solution for single-sided deafness.
A CROS system uses a microphone on the deaf ear to pick up sound, which is then wirelessly transmitted to a receiver worn on the ear with normal hearing. This effectively routes sound from the non-hearing side to the functional ear, helping to overcome the “head shadow” effect that makes hearing sounds from the deaf side difficult. For patients with a profound, non-recoverable loss, a cochlear implant may be considered to restore hearing perception. In addition to devices, auditory rehabilitation therapy can help the brain adapt to the altered sound input.