Tinnitus is the perception of sound, such as a ringing, buzzing, hissing, or whooshing noise, when no external sound source is present. This auditory sensation is a common symptom following a traumatic event affecting the head or neck.
A head injury involves any trauma to the scalp, skull, or brain, ranging from a mild bump to a severe blow. The connection between head trauma and the onset of persistent sound perception is well-established in clinical practice. Physical forces from an injury can disrupt the delicate mechanics and neural pathways of the auditory system.
Confirmation of the Link
A link exists between head injuries and the onset of tinnitus, often referred to as post-traumatic tinnitus. This condition is a frequently reported symptom following various types of head and neck trauma. Concussions, which are a form of mild traumatic brain injury (TBI), are a particularly common trigger for this auditory symptom. Up to 53% of individuals who experience a TBI may develop tinnitus as a result of the injury.
The forceful, rapid movement of the head and neck, such as that experienced in a whiplash injury, can also induce tinnitus even without a direct blow to the head. This rapid acceleration and deceleration can strain or irritate nerves and muscles in the cervical spine area. Tinnitus following trauma can manifest immediately or develop days later, and it can be temporary or become a long-lasting, chronic condition.
How Head Trauma Affects Hearing Pathways
Physical trauma can induce tinnitus through damage at multiple points along the auditory and neurological pathways. One mechanism involves direct structural damage to the middle and inner ear. A severe impact may cause a fracture near the inner ear or disrupt the ossicular chain, which is the alignment of the three tiny bones responsible for transmitting sound vibrations.
Trauma can also damage the delicate hair cells within the cochlea, which are responsible for converting sound waves into electrical signals for the brain. When these hair cells are damaged, they reduce the normal sensory input to the brain, which the central auditory system may interpret as a phantom sound. Furthermore, the auditory nerve, also known as the cochlear nerve or Cranial Nerve VIII, can become damaged or irritated by the trauma. This nerve damage can cause the nerve fibers to become hyperactive or begin misfiring, sending erratic signals to the brain that are perceived as sound.
A third major mechanism involves the central nervous system, resulting in what is often termed somatic tinnitus. This occurs through maladaptive changes in the neural connections between the auditory system and the somatosensory system, which processes physical sensations from the body. Specifically, the dorsal cochlear nucleus in the brainstem can become hyperactive after trauma has reduced its normal auditory input. Somatosensory inputs from the head, jaw, and neck can become up-regulated, leading to a sound perception that can sometimes be modulated by jaw or neck movements.
Medical Assessment and Testing
The evaluation of post-traumatic tinnitus begins with a comprehensive medical history, focusing on the nature and extent of the head injury and the specific characteristics of the perceived sound. An otolaryngologist or audiologist will assess the severity, pitch, and duration of the tinnitus, as well as any associated symptoms like hearing loss or dizziness.
A pure-tone audiogram is a standard initial test that measures hearing thresholds across different frequencies to determine if hearing loss accompanies the tinnitus. Specialized high-frequency audiometry may also be used to match the pitch and intensity of the phantom sound, which helps in understanding the underlying pathology. If the tinnitus is heard only in one ear, or if it is pulsatile—meaning it beats in time with the heart—imaging tests are often ordered to rule out structural issues.
Magnetic Resonance Imaging (MRI) or Computed Tomography (CT) scans may be used to visualize the inner ear, the eighth cranial nerve, and the surrounding brain structures. A CT scan is often preferred for visualizing bony structures, while an MRI provides superior detail of soft tissues and nerves to detect potential masses or vascular changes. These imaging techniques help identify or exclude rare but serious causes of tinnitus, such as a tumor near the auditory nerve or a vascular abnormality.
Treatment Approaches
Management of post-traumatic tinnitus focuses on reducing the distress and impact of the sound. Sound therapy is a common approach that involves introducing external noise to either mask the tinnitus or help the brain habituate to the sound. Devices like hearing aids, particularly if hearing loss is present, or dedicated sound generators can provide background noise to make the tinnitus less noticeable.
Behavioral therapies are considered the most effective management strategies for the emotional and cognitive impact of tinnitus. Cognitive Behavioral Therapy (CBT) for tinnitus is highly recommended and aims to change the patient’s reaction to the sound. This therapy teaches coping skills to reduce the anxiety, stress, and negative thoughts associated with the condition, promoting habituation.
Tinnitus Retraining Therapy (TRT) combines directive counseling with sound therapy to help the brain reclassify the tinnitus signal as neutral. While no medication is specifically approved to treat tinnitus, pharmacological interventions are often used to address co-occurring symptoms. Medications may be prescribed to manage anxiety, depression, or sleep disturbances, which can be exacerbated by the constant perception of sound.