A Primer on Traumatic Brain Injury and Concussions

 

Concussion-related amnesia usually presents as loss of memory for the traumatic event but may also include retrograde amnesia (loss of recall for events immediately before the trauma) and anterograde amnesia (loss of recall for events after the trauma).  Additional early-onset symptoms concussions include headache, dizziness, nausea and vomiting.¹⁵ Later emerging symptoms may include mood and cognitive disturbances, sensitivity to light and noise, and sleep disturbances.¹⁶

The initial assessment of a patient with a concussion or mild TBI should include a neurologic examination and mental status evaluation.¹⁷ Since the subtle cognitive deficits associated with concussion and mild TBI may be difficult to detect, several specialized diagnostic instruments have been developed. These include: Standardized Assessment of Concussion, Post-Concussion Symptom Scale and Graded Symptom Checklist, Sport Concussion Assessment Tool 2 and the Westmead Post-Traumatic Amnesia scale. For patients experiencing prolonged unconsciousness, residual mental status changes, or neurologic dysfunction, urgent neuroimaging and neurosurgical consultation are strongly recommended.¹²

Management

For patients with mild TBIs, outpatient observation for at least 24 hours is recommended due to the  increased  risk of intracranial complications.¹⁸ For patients at risk for immediate complications from head injury hospitalization is indicated.^19,20

Patients with an uncomplicated concussion should be advised to engage in a 2- hour period of rest from physical and cognitive activities before returning back to normal activities. Patients with prolonged symptoms should be considered for re-evaluation and continued treatment.²¹

Sequelae

With appropriate observation and management, most patients with concussions will experience complete recovery.^{22, 23} But serious sequelae from concussions may occur including post-traumatic epilepsy, cortical contusions, intracranial hemorrhage, skull or facial bone fractures, spine or spinal cord injuries, eye injuries, and damage to cervical vasculature.²⁰

The “second impact syndrome” (another serious sequelae of concussion) may occur. The second impact syndrome is described as  diffuse cerebral swelling which occurs after a second concussion.^24,25 Additional persistent sequelae of mild TBIs include post-concussion syndrome ( headache, vertigo, nonspecific dizziness, neuropsychiatric symptoms, and cognitive impairment²⁶, post-traumatic headaches²⁷, post- traumatic vertigo,²⁸ and post-traumatic epilepsy. Mild TBI may affect specific cranial nerve injuries.²⁹

Chronic traumatic encephalopathy is believed to be caused by repeated concussions which produce cumulative neuropsychological deficits.^30,31 Chronic traumatic encephalopathy has been associated with cognitive impairment, neuropsychological symptoms (personality changes, depression, and suicidality), Parkinsonism and speech and gait abnormalities.^32,33,34 Current studies suggest that chronic traumatic encephalopathy may be associated with the reported increased incidence of dementia among U.S. professional football players.^35,36,37,38 Other studies suggest soldiers with histories of multiple blast injuries may be more likely to develop chronic traumatic encephalopathy.^39,40