What are the differential diagnoses for a young boy who sustained a head collision and experienced a brief loss of consciousness lasting less than 10 minutes?

Differential Diagnoses for Young Boy with Head Collision and Brief Loss of Consciousness

This young boy has sustained a mild traumatic brain injury (mTBI) with loss of consciousness <10 minutes, placing him at intermediate-to-high risk for clinically important traumatic brain injury requiring urgent CT imaging and close monitoring. 1, 2

Primary Diagnostic Considerations

Mild Traumatic Brain Injury (Concussion)

• Most likely diagnosis given the mechanism (head collision) and brief loss of consciousness lasting <10 minutes, which meets CDC and American Congress of Rehabilitation Medicine criteria for mTBI (LOC <30 minutes with GCS 13-15) 1, 2
• Loss of consciousness is an independent predictor of intracranial injury with odds ratio of 1.9 (95% CI 1.3-2.6) 2
• Up to 15% of patients with GCS score of 15 will have acute lesions on head CT despite appearing clinically well 2
• Serial GCS assessments are essential as a single score has limited prognostic value—a declining or persistently low score indicates poorer prognosis 2, 3

Intracranial Hemorrhage Requiring Intervention

• Epidural hematoma: Classic presentation includes brief loss of consciousness followed by a "lucid interval" before deterioration, though this occurs in only a minority of cases 4, 5
• Subdural hematoma: More common in children with acceleration-deceleration injuries 6
• Subarachnoid hemorrhage: Rare but critical—can present with headache, vomiting, and altered mental status; may indicate underlying vascular lesion such as aneurysm rupture (18% of pediatric cerebral hemorrhages are pure meningeal forms) 4
• Intraparenchymal contusion: Children with intraparenchymal lesions despite GCS 13-15 can perform on neuropsychological testing similar to those with moderate TBI (GCS 9-12) 2

Skull Fracture

• May occur in up to 50% of children with intracranial injuries 1
• Depressed skull fractures require immediate neurosurgical consultation 6
• Basilar skull fractures present with Battle's sign, raccoon eyes, hemotympanum, or CSF leak 1

Post-Traumatic Seizure

• Children with post-traumatic seizures have a 16% rate of traumatic brain injury on CT requiring hospitalization 6
• Requires immediate EMS activation and urgent neuroimaging 6

Cervical Spine Injury

• Must be considered in any significant head trauma with altered consciousness 6
• Spinal precautions are mandatory until cervical spine injury is excluded 6

Risk Stratification Using PECARN Criteria

High-Risk Features (Require Urgent CT)

• GCS <15 at 2 hours post-injury 1
• Signs of altered mental status (agitation, somnolence, repetitive questioning, slow response) 1
• Signs of basilar skull fracture 1
• Palpable skull fracture (in children <2 years) 1

Intermediate-Risk Features (Consider CT vs. Observation)

• For children ≥2 years: History of loss of consciousness, vomiting, severe mechanism of injury, or severe headache with GCS 15 and normal mental status 1
• **For children <2 years**: Loss of consciousness >5 seconds, severe mechanism of injury, or not acting normally per parent with GCS 15 and normal mental status 1
• Risk of clinically important TBI is approximately 0.8-0.9% in this group 1

Very Low-Risk Features (May Safely Forgo CT)

• Isolated loss of consciousness with no other PECARN predictors carries only 0.5% risk of clinically important TBI 7
• Children meeting very low-risk criteria have <0.02% estimated risk of clinically important traumatic brain injury 1

Critical Management Pitfalls to Avoid

Do not assume "mild" means benign: The term "mild" refers to initial injury classification, not outcome severity—5-15% of patients with mild TBI may have compromised function 1 year after injury 2

Do not rely on a single GCS determination: Serial assessments every 15-30 minutes are essential for detecting deterioration 2, 3

Do not miss non-accidental trauma: Maintain high index of suspicion in children <2 years old, especially if history is inconsistent with injury pattern or if there is a reported "lucid interval" without epidural hematoma (likely indicates false history) 6, 5

Do not discharge without proper observation: Even children with isolated LOC require either CT imaging or a minimum 4-6 hour observation period with serial neurological assessments 7, 8

Do not ignore associated symptoms: Presence of vomiting (90-99% of physicians hospitalize), abnormal vital signs (97-100% hospitalize), witnessed change in consciousness (92-99% hospitalize), or unreliable caretaker at home (91-98% hospitalize) should prompt admission 8

Immediate Diagnostic Approach

Obtain urgent non-contrast head CT if any of the following are present: 1, 6

• GCS <15
• Any signs of altered mental status beyond brief initial confusion
• Severe mechanism of injury (high-speed motor vehicle collision, fall >3-5 feet depending on age, struck by high-impact object)
• Severe or worsening headache
• Persistent vomiting (≥2 episodes)
• Signs of skull fracture on examination
• Age <2 years with concerning parental report of abnormal behavior

Consider observation vs. CT for isolated loss of consciousness with completely normal examination and no other risk factors, though parental preference, multiple risk factors, or young age (<2 years where assessment is challenging) favor imaging 1, 7

Rare but Critical Differentials

Underlying vascular lesion (aneurysm): Though rare in children (1.4/100,000 per year), 57% of intraventricular or subarachnoid hemorrhages in children have underlying aneurysms; requires MR angiography if subarachnoid hemorrhage is identified 4

Diffuse axonal injury: May present with disproportionate neurological dysfunction relative to CT findings; MRI is more sensitive but impractical in acute setting 1