Mild traumatic brain injury
Background
- Definition: GCS 14-15
- Neurologic dysfunction that varies without gross lesions (ie patients have trouble with memory, attention, and executive functioning
- Occurs after a blunt force or acceleration-deceleration head injury
- Likely secondary to metabolic insult ie low oxygen state, ion changes
- Structural imaging on MRI or CT might not indicate any injury
- Often evidence on microscopic level of injury with histology
- Important to not expose the already injured brain to repeated insults which is why there are usually worsening symptoms after a repeat concussion
TBI Pathophysiology
Primary injury
- Contusions
- Bruises to brain parenchyma
- Hematomas
- Epidural hematoma
- Subdural hematoma
- Intraparenchymal
- Intraventricular
- Subarachnoid hemorrhage
- Diffuse axonal injury
- Direct cellular damage
- Neurons
- Axons
- Tearing and shearing of tissues
Secondary injury
Brain swelling causes increased ICP which compresses the tissue causing ischemia with direct compression of the vasculature causing brain tissue herniation and brain death
- Leads to expansion of the original injury (predominantly metabolic insult)
- Calcium and sodium shifts
- Mitochondrial damage
- Production of free radicals
- Ultimately leads to damage to axonal integrity and axonal transport
- Enzyme activity leads to apoptosis
- Microscopic structural injury is often unidentifiable on CT or MRI
Cerebral Blood Flow and Autoregulation
- vasoconstriction
- HTN, Hypocarbia, alkalosis
- No good way to measure cerebral blood flow
- Use CPP as surrogate
- CPP is amount of pressure needed to perfuse the brain
- CPP=MAP-ICP
- When ICP elevates, CPP decreases
- Normal ICP
- 15 in adults
- <10 to 15 in children
- 1.5 to 6.0 in infants
- Use CPP as surrogate
- Autoregulation allows the body to control the cerebral blood flow
- Autoregulatory mechanism is damaged in most TBI patients
Clinical Features
- Most consistent abnormality is subtle impairments in cognitive function
- Attention, concentration, amnesia, memory, processing speed, reaction time, calculation, executive function
- Physical signs/symptoms
- Behavioral changes
- Irritability, depression, anxiety, sleep disturbances, problems related to school/work, emotional lability, loss of initiative, loneliness and helplessness
Differential Diagnosis
Head trauma
- Traumatic brain injury
- Orbital trauma
- Maxillofacial trauma
- Scalp laceration
- Skull fracture
- Pediatric head trauma
Evaluation
Workup
- Consider head CT (rule out intracranial hemorrhage)
- Use validated decision rule to determine need
- Avoid CT in patients with minor head injury who are at low risk based on validated decision rules.[1]
- Consider cervical and/or facial CT
- No reliable test that can confirm diagnosis of concussion
- Clinical Signs and Symptoms may occur immediately or be delayed by days-weeks
- Important to document full examination and should do gait and congnition testing
- Mini Mental State Exam
- Standardized Assessment for Concussion
- Takes 10-15 mins to administer often not performed in ED
Types
- Simple concussion
- Gradual resolution of symptoms within 7-10d
- Complex concussion
- Persisting symptoms or cognitive impairment
- Symptoms with exertion
Management
Simple
- Limitations on playing and training while symptomatic
- Follow up with primary care provider
Complex
- Refer to sports medicine or concussion specialist
Disposition
- Given good follow up instructions detailing a graded return-to-activity program and symptoms to anticipate during recovery [2]
- Discharge patient to care of responsible individual
- Patients might not understand discharge instructions so repeat them to the individual taking care of the patient
- Recommend strict rest for 1-2 days with gradual introduction back to regular activity[3]
- Physical activity at any level (light aerobic, moderate, full) within first 7 days compared with no activity associated with lower rates of persistent symptoms at 28 days (29% vs. 40%)[4]
- Multicohort study - 2400 children, aged 5-18, in the emergency department
- Still recommend strict rest for first 24-48 hours
Prognosis
See also post-concussive syndrome
- At 3 mo after injury 20-40% are symptomatic
- with treatment for the most common symptoms of headache, difficulty concentrating and short-term memory difficulties being rest and in some circumstances NSAIDS.
- At 1 yr after injury 15% are symptomatic
See Also
References
- ↑ Choosing wisely ACEP
- ↑ Ronsford J, et al. Impact of early intervention on outcome after mild traumatic head in adults. 2002
- ↑ Thomas DG, Apps JN, Hoffmann RG, et al. Benefits of strict rest after acute concussion: a randomized controlled trial. Pediatrics. 2015; 2(135):213-223.
- ↑ Grool AM et al. Association Between Early Participation in Physical Activity Following Acute Concussion and Persistent Postconcussive Symptoms in Children and Adolescents. JAMA. 2016;316(23):2504-2514.