Assessment and Management of Post-Traumatic Amnesia After Head Injury
Immediate Assessment of Post-Traumatic Amnesia
Post-traumatic amnesia (PTA) should be assessed prospectively using validated standardized tools such as the Abbreviated Westmead Post-Traumatic Amnesia Scale, which can efficiently identify patients with cognitive impairment within 4 hours and determine the need for admission or further investigation. 1
Key Assessment Components
Evaluate both retrograde amnesia (inability to recall events before injury) and anterograde amnesia (inability to form new memories after injury) by asking specific questions about pre-injury and post-injury events. 2
Test orientation to person, place, and time, along with the ability to consistently remember events for at least the last 24 hours—a patient has emerged from PTA only when fully oriented with return of continuous memory. 3
Document the specific duration and characteristics of both retrograde and anterograde amnesia, as this information is critical for assessing injury severity and prognosis. 4
Recognize that PTA affects multiple cognitive domains beyond memory, including attention, information processing, language, perception, and critical judgment, all of which should be assessed. 5
Common Pitfall in Assessment
Avoid retrospective assessment of PTA, as it is unreliable—factors such as analgesics, anesthesia, acute stress disorder, and repeated questioning can promote false recall or confabulations that were not actually experienced during the injury period. 6
Be aware that retrograde amnesia may falsely appear to improve over time as patients are exposed to others recounting the event, leading to false recollection rather than true memory recovery. 2
Neuroimaging Decision-Making in Patients with PTA
Any patient presenting with post-traumatic amnesia requires emergent head CT if they exhibit any high-risk features: age ≥65 years, GCS <15, focal neurologic deficit, vomiting (>1 episode), severe headache, signs of basilar skull fracture, coagulopathy or anticoagulant use, or dangerous mechanism of injury (fall >3 feet or 5 stairs). 2
Critical Evidence Points
The presence of amnesia together with loss of consciousness indicates a higher likelihood of significant intracranial pathology requiring imaging. 2
Loss of consciousness is an independent predictor of intracranial injury with an odds ratio of 1.9 (95% CI 1.3-2.6). 4
Up to 15% of patients with GCS score of 15 will have acute lesions on head CT, and patients with intraparenchymal lesions despite GCS 13-15 can perform on neuropsychological testing similar to those with moderate TBI. 4
The absence of loss of consciousness or amnesia alone does not rule out the need for CT when other high-risk features are present—two well-designed studies showed these factors are insufficiently sensitive to identify all at-risk patients. 2
Discharge Criteria and Safety Planning
Patients may be safely discharged only when head CT is negative (or imaging deemed unnecessary based on absence of all high-risk features) AND the patient has cleared PTA testing, demonstrating full orientation and continuous memory formation. 2
Discharge Instructions (Verbal and Written)
Provide discharge instructions both verbally and in writing at a sixth- to seventh-grade reading level to ensure comprehension. 2
Instruct someone to check on the patient every 2-3 hours during the first 24 hours, including waking them from sleep. 2
Advise complete avoidance of alcohol for at least 48 hours, no driving for at least 24 hours or until cleared by physician, and no contact sports or activities with fall risk for at least one week. 2
Recommend limiting screen time as this can worsen headache and cognitive symptoms. 2
Advise avoiding aspirin, ibuprofen, and other NSAIDs for 48 hours; acetaminophen is preferred for headache management. 2
Red Flag Symptoms Requiring Immediate Return
Patients must return immediately to the emergency department if they develop: repeated vomiting, worsening or severe headache unresponsive to acetaminophen, new or worsening confusion or memory problems, slurred speech, weakness or numbness in extremities or face, vision changes, seizures, unequal pupils, clear or bloody drainage from nose or ears, increasing drowsiness or difficulty staying awake, loss of consciousness, or behavioral changes. 2
Management of Behavioral Disturbance During PTA
Behavioral and environmental measures form the mainstay of treatment for patients in PTA with agitation, while pharmacological interventions should be avoided where possible as they may worsen agitation and prolong cognitive recovery. 3
Environmental Management Strategies
Maintain a calm, quiet environment with minimal stimulation to reduce agitation. 3
Use reorientation techniques and provide consistent caregivers when possible. 3
Ensure patient safety through appropriate supervision rather than chemical restraint. 3
Post-Concussive Symptom Monitoring and Follow-Up
Document post-concussive symptoms at initial assessment using a standardized symptom scale, with headache being the most frequently reported symptom, followed by memory problems, difficulty concentrating, dizziness, and balance disturbances. 2
Follow-Up Algorithm
Schedule routine follow-up in 3-5 days if symptoms persist after discharge. 2
Reassess patients regularly to determine their need for further rehabilitation and to facilitate safe discharge planning. 3
Refer to a traumatic brain injury specialist if symptoms persist beyond three weeks, or earlier if the patient plans to return to sport. 2
Advise gradual return to normal activities over 1-2 weeks as symptoms resolve, with cognitive rest initially then gradual resumption. 2
Do not clear patients for return to contact sports until they are completely symptom-free and have physician clearance. 2
Prognostic Value of PTA Duration
The longer the duration of PTA, the poorer the performance on everyday memory testing at one month post-injury (multiple R = 0.88), making PTA duration a valuable index of brain injury severity and predictor of long-term cognitive outcomes. 7
Recovery Pattern
Patients typically recover orientation first, then the capacity to recognize new information, and finally the ability to recall this information. 7
PTA duration of less than 24 hours defines mild TBI according to American Congress of Rehabilitation Medicine and CDC criteria, though 5-15% of patients with mild TBI may have compromised function 1 year after injury. 4
Special Considerations for Older Adults (≥65 Years)
Age ≥65 years is itself an indication for CT imaging regardless of other factors, and these patients require extended observation periods due to higher risk of delayed bleeding. 2
Carefully review all medications, especially anticoagulants and antiplatelet agents, as anticoagulated patients have a 1.4-4.5% risk of delayed hemorrhage even with initially negative CT. 8
Monitor blood pressure carefully and conduct home safety assessment before discharge to prevent repeat falls. 2