What is the classification, investigation, and management of head injuries, including their complications and neurological sequelae?

Classification of Head Injury

Head injuries are classified by severity using the Glasgow Coma Scale (GCS): mild (GCS 13-15), moderate (GCS 9-12), and severe (GCS 3-8), with this classification directly predicting mortality, morbidity, and need for neurosurgical intervention. 1

Severity-Based Classification

Mild Traumatic Brain Injury (mTBI)

• GCS score 13-15 after 30 minutes post-injury or on presentation 1
• Must include one or more of the following: confusion/disorientation, loss of consciousness ≤30 minutes, post-traumatic amnesia <24 hours, transient neurologic abnormalities (focal signs, symptoms, or seizure) 1
• Represents 70-90% of all head injuries presenting to emergency departments 1
• 10-15% will have acute intracranial injury on CT, but <1% require neurosurgical intervention 1
• Important caveat: Some authorities recommend classifying GCS 13 as "moderate" rather than "mild" due to higher rates of intracranial pathology and worse outcomes 1

Moderate Head Injury

• GCS score 9-12 2, 3
• 30% have negative CT scans, 31% show space-occupying mass 2
• Intermediate mortality and morbidity between mild and severe injury 2
• At 3 months, only 38% achieve good recovery (compared to 75% with mild injury) 2
• 66% remain unemployed at 3 months post-injury 2

Severe Head Injury

• GCS score 3-8 1
• Requires immediate intracranial pressure monitoring and intensive care 1, 4
• Highest mortality and morbidity rates 2

Anatomic/Pathophysiologic Classification

Concussion (Functional Injury)

• No structural abnormality on standard neuroimaging by definition 5
• Results from neurometabolic cascade with increased energy demand and decreased cerebral blood flow 5
• 15-20% develop persistent symptoms beyond 2 weeks 5

Contusion (Structural Injury)

• Requires neuroimaging (CT or MRI) for diagnosis 5
• Represents actual brain parenchymal damage 5
• Requires hospitalization for neurological monitoring in most cases 5

---

Investigations

Initial Assessment Algorithm

Step 1: Clinical Evaluation

• Immediate GCS scoring (must be performed after any period of loss of consciousness has resolved) 1
• Document presence/absence of: loss of consciousness duration, post-traumatic amnesia, confusion/disorientation, focal neurologic deficits 1
• Identify red flag symptoms: repeated vomiting, worsening headache, focal deficits, altered mental status, seizures 5

Step 2: Neuroimaging Decision

For Mild TBI (GCS 13-15):

• CT head is usually appropriate if clinical decision rules indicate risk factors 1
• Mandatory CT indications include: signs of skull base fracture (rhinorrhea, otorrhea, hemotympanum, Battle's sign, raccoon eyes), displaced skull fracture, post-traumatic seizure, focal neurologic deficit, coagulopathy, anticoagulant therapy 1
• CT not indicated if clinical decision rules are negative and GCS 15 without risk factors 1

For Moderate TBI (GCS 9-12):

• Brain and cervical spine CT should be performed systematically and without delay 1

For Severe TBI (GCS 3-8):

• Immediate non-contrast head CT 1
• Cervical spine CT 1

Step 3: Advanced Monitoring (Moderate-Severe TBI)

Transcranial Doppler:

• Mean blood flow velocity <28 cm/s or diastolic velocity <20 cm/s with pulsatility index >1.4 predicts poor outcome 1
• Should be part of initial FAST examination in polytrauma 1

Intracranial Pressure Monitoring:

• Continuous ICP monitoring indicated for severe TBI (GCS 3-8) 1, 4
• Methods include: intraventricular catheter, subarachnoid screw, or Rickham reservoir system 4

Biomarkers:

• Not recommended for routine clinical use in initial severity assessment 1

Step 4: Serial Monitoring

Mild TBI:

• Periodic neurological status and vital signs assessment 4
• Repeat imaging only if clinical deterioration 5

Moderate-Severe TBI:

• Serial neurological examinations to detect deterioration 5, 4
• Repeat CT as clinically indicated to assess for hematoma expansion 5
• Continuous monitoring of ICP, respiratory parameters, vital signs 4

---

Major Complications

Immediate Life-Threatening Complications

Intracranial Hemorrhage

• Subdural hematoma in moderate TBI: 65% mortality or severe disability, 0% good recovery 2
• Requires immediate neurosurgical evaluation if mass effect present 2

Secondary Brain Injury from Hypotension/Hypoxia

• Systolic blood pressure <90 mmHg for ≥5 minutes significantly increases morbidity and mortality 1
• Hypoxemia (SaO₂ <90%) associated with increased mortality and worse neurological outcome 1
• Combined hypotension and hypoxemia: 75% mortality rate 1
• Maintain mean arterial pressure ≥80 mmHg in severe TBI 1

Herniation Syndromes

• Detected by clinical deterioration, pupillary changes, posturing 1
• Requires immediate intervention to reduce ICP 1

Neurological Complications

Post-Concussive Syndrome

• Occurs in 15-20% of mild TBI patients beyond 2 weeks 5
• Most common symptoms: headaches (93%), memory difficulties (90%), difficulties with activities of daily living (87%) 2
• Additional manifestations: dizziness, fatigue, irritability, anxiety, insomnia, noise sensitivity 6
• Resolution in most patients by 3-6 months, but persistent symptoms occur in a distinct minority for months to years 6

Cognitive Impairment

• Significant neuropsychological deficits demonstrated on Halstead-Reitan Battery even in "good recovery" patients 2
• Patients with intraparenchymal lesions perform similar to moderate TBI on neuropsychological testing despite GCS 13-15 1
• 5-15% have compromised function at 1 year depending on disability definition 1

Post-Traumatic Seizures

• Higher risk with contusion compared to concussion 5
• Requires counseling and potential prophylaxis in contusion patients 5

Cranial Nerve Dysfunction

• Multiple cranial nerve symptoms possible as sequelae 6
• Includes anosmia, visual disturbances, hearing loss, vestibular dysfunction 6

Chronic Complications (Contusion)

• Post-traumatic epilepsy requiring long-term neurosurgical follow-up 5
• Hydrocephalus as late complication 5
• May require formal neuropsychological rehabilitation programs 5

Functional Outcomes

Employment Impact

• Mild TBI: 33% unable to return to work, predicted by premorbid characteristics (age, education, socioeconomic status) 2
• Moderate TBI: 66% unable to return to work at 3 months, predicted by injury severity measures (coma length, CT findings, discharge GCS) 2

Risk Factors for Poor Outcome

• Age >40 years 6
• Lower educational, intellectual, and socioeconomic level 6
• Female gender 6
• Alcohol abuse 6
• Prior head injury 6
• Multiple trauma 6

Critical Management Pitfalls

Concussion-Specific

• Never allow same-day return to play after diagnosed concussion 5
• Avoid strict prolonged rest exceeding 3 days—this worsens outcomes 5
• Do not return to play while taking symptom medications—indicates incomplete recovery 5
• Be more conservative with patients <18 years due to effects on maturing brain 5

Contusion-Specific

• Never discharge without appropriate imaging to rule out structural injury 5
• Do not assume clinical improvement means radiographic stability—repeat imaging often necessary 5
• Never clear for contact sports without neurosurgical consultation 5
• Many patients permanently disqualified from contact sports due to catastrophic reinjury risk 5

General

• Litigation/compensation does not cure symptoms—most patients have genuine complaints, not malingering 6
• Subdural hematoma in moderate TBI has extremely poor prognosis—requires aggressive early intervention 2