A concussion, medically defined as a mild traumatic brain injury (mTBI), involves a temporary functional disturbance of the brain resulting from a blow or jolt to the head. While many symptoms resolve within a few weeks, a significant subset of individuals experiences symptoms that persist or emerge long after the initial injury. Vertigo can indeed appear months later, indicating that the physical trauma caused a lasting disruption to the body’s complex balance system.
The Definition of Persistent Post-Concussion Symptoms
The persistence of symptoms beyond the expected recovery period is formally recognized as Persistent Post-Concussion Symptoms (PPCS) or Post-Concussion Syndrome (PCS). A diagnosis of PCS is typically considered when symptoms continue for more than three months after the head injury, affecting 15% to 30% of patients.
Vertigo and dizziness are the second most frequent symptoms reported after a concussion, following headache. A key feature of PCS is the potential for delayed onset; individuals may feel normal for weeks before experiencing a gradual increase in issues like dizziness and fatigue. Other persistent symptoms often include chronic headaches, cognitive fog, difficulty concentrating, and sleep disturbances.
How a Concussion Disrupts the Vestibular System
The sensation of vertigo, which is the illusion of spinning or motion, is a direct result of a disruption within the vestibular system. This system is a complex network involving the inner ear structures, the vestibular nerves, and the processing centers in the brainstem and cerebellum. The rapid acceleration and deceleration forces that cause a concussion can physically damage or functionally impair any part of this system.
Damage can be categorized as peripheral, affecting the inner ear or the vestibular nerve, or central, impacting the brain’s processing centers. The mechanical forces of the injury can cause a shockwave that travels through the skull to the inner ear, potentially damaging the delicate structures responsible for balance. In the brain, trauma can disrupt the neurovascular coupling, leading to chronic dizziness and balance problems if areas like the cerebellum are compromised.
Specific Conditions That Cause Delayed Vertigo
Vertigo appearing months later is often linked to the slow development of specific post-traumatic conditions.
Persistent Postural-Perceptual Dizziness (PPPD)
PPPD is a chronic disorder where dizziness is present on most days for at least three months. It is characterized by a non-spinning sense of unsteadiness, swaying, or rocking. This is worsened by upright posture, motion, or complex visual environments, such as walking through a crowded store. The condition often begins after an acute vestibular event, like a concussion, and involves the brain becoming hyperfocused on balance, leading to a maladaptive pattern of processing sensory signals.
Post-Traumatic Benign Paroxysmal Positional Vertigo (BPPV)
BPPV is the most common vestibular disorder after a concussion. It occurs when tiny calcium carbonate crystals (otoconia) are dislodged from their normal position and drift into the fluid-filled semicircular canals. This displacement causes brief, intense episodes of spinning vertigo, typically lasting less than a minute, triggered by specific changes in head position. While BPPV often presents immediately after trauma, delayed onset can be explained by the time it takes for the dislodged debris to settle into the canals, sometimes manifesting weeks or months later.
Vestibular Migraine
A third major cause of delayed vertigo is the Vestibular Migraine, which can be triggered or exacerbated by the concussion. These episodes are not always accompanied by a traditional headache. They may involve recurrent, spontaneous vertigo lasting minutes to days, sometimes with sensitivity to light, noise, and motion. The underlying mechanism involves the trauma affecting the brain’s pathways that regulate both vestibular function and migraine activity.
Evaluating and Treating Long-Term Dizziness
A comprehensive evaluation by a specialist is necessary to identify the specific underlying cause of long-term dizziness and vertigo. Specialists may include a neurologist, an otolaryngologist, or a physical therapist specializing in vestibular disorders. The evaluation often involves a detailed physical and neurological exam, including the Vestibular Ocular Motor Screening (VOMS) and specific positional testing like the Dix-Hallpike maneuver to check for BPPV.
The primary and most effective treatment is Vestibular Rehabilitation Therapy (VRT), a specialized form of physical therapy. VRT uses targeted exercises to help the brain adapt to the altered or conflicting signals it is receiving from the vestibular system. For BPPV, specific head and body movements known as Canalith Repositioning Maneuvers can effectively guide the dislodged crystals back to their proper location. Conditions like PPPD or Vestibular Migraine may require a multimodal approach that includes VRT, lifestyle modifications, and sometimes medication management.