In the US, 44 million children and 170 million adults participate in sports, and there are approximately 3.8 million sports-related concussions annually.14,15 Concussions are the mildest form of traumatic brain injury; it is a transient functional disorder caused by direct trauma, rapid acceleration-deceleration of the head, or blast forces. Post-concussion syndrome has been reported to occur in 30% to 80% of concussed individuals; this wide variation may reflect different reporting standards, as well as comorbid psychiatric and medicolegal issues. While it typically resolves within 3 months, post-concussion syndrome may persist in about 20% of concussed individuals.
Headache and dizziness are very common symptoms. Other symptoms include light and sound sensitivity, nausea, tinnitus, cognitive dysfunction (mental fog), problems with visual focus, sleep changes, depression, anxiety, and irritability. Dizziness may be due to direct CNS effects of the trauma (causing axonal injury and other microstructural damage), vestibular migraine, and neuropsychiatric disorders (eg, anxiety, depression, PTSD).16 Post-traumatic benign paroxysmal positional vertigo is not uncommon in concussion, but other post-traumatic injuries to the peripheral vestibular apparatus (eg, perilymphatic fistula, otolithic injury, labyrinthine concussion) are rarely encountered. A detailed history and examination are crucial when assessing dizziness because the treatment needs to address the underlying etiology.
Dizziness may be a manifestation of many neurodegenerative disorders. At presentation, Parkinson disease patients may describe the shuffling or festinating gait as being “dizzy” or “off balance.” Medications such as levodopa or dopamine agonists (eg, pramipexole, ropinorole) may cause orthostatic hypotension, and hence presyncopal dizziness.
The Parkinson-plus disorders often cause many symptoms that are construed as “dizziness.” Multiple system atrophy causes dysautonomia (causing orthostatic presyncope or syncope), vertigo, nystagmus (causing oscillopsia), and/or cerebellar findings (leading to gait ataxia). Progressive supranuclear palsy often presents with falls and complaints of imbalance; loss of downgaze often causes imbalance when descending stairs.
Spinocerebellar ataxias are a group of inherited degenerative disorders characterized by insidious, progressive cerebellar ataxias sometimes accompanied by other neurologic deficits depending on the type. Early in the disease, patients with spinocerebellar ataxias may see neurologists for evaluation of ataxia or oscillopsia.
Dizziness that arises from CNS causes is not infrequently encountered in neurologic practice. The most common CNS cause of dizziness is vestibular migraine, while posterior fossa strokes constitute the most urgent etiology of acute vestibular syndrome that carries potentially significant morbidity and even mortality. A detailed history and careful neurologic examination focused on the vestibular system almost always reveal clues about the underlying cause of dizziness.
Dr Beh is Assistant Professor of Neurology, Director, Vestibular & Neuro-Visual Disorders Clinic, University of Texas Southwestern Medical Center at Dallas.
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