Differentials
Epidural hematoma
SIGNS / SYMPTOMS
"Lucid interval," younger patients, usually an associated skull fracture.
Rarer in older patients (>60 years).
INVESTIGATIONS
CT of the brain shows lenticular shape that does not normally cross suture lines.
Intracerebral hematoma
SIGNS / SYMPTOMS
There may be no differences in symptoms and signs.
INVESTIGATIONS
CT of the brain shows hematoma within brain parenchyma.
Diffuse axonal injury
SIGNS / SYMPTOMS
History of trauma involving shear or acceleration/deceleration force; high-grade diffuse axonal injury typically results in coma.
INVESTIGATIONS
Absence of subdural collection on CT of the brain; small hyperdense lesions may be seen. MRI of the brain with gradient-recalled echo or susceptibility-weighted imaging shows small regions of susceptibility artefact in the cortex, corpus callosum, or brainstem.
Stroke
SIGNS / SYMPTOMS
No history of preceding trauma (though a fall may have resulted from the stroke). May have a history of atrial fibrillation, cardiac arrhythmia, or prothrombotic disorder. May have had a previous transient ischemic attack.
INVESTIGATIONS
Ischemic stroke: Noncontrast CT can shows hypoattenuation (darkness) of the brain parenchyma and loss of grey matter/ white matter differentiation; hyperattenuation (brightness) in an artery indicates a clot within the vessel lumen.
Hemorrhagic stroke: Noncontrast CT shows hyperattenuation suggestive of acute blood, often with surrounding hypoattenuation due to edema.
Seizure
SIGNS / SYMPTOMS
After postictal state, patient typically returns to baseline. There may be a lingering Todd's paralysis for up to 48 hours after a focal motor seizure.
INVESTIGATIONS
Electroencephalogram may show seizure activity.
Substance abuse
SIGNS / SYMPTOMS
Usually no history of trauma.
Known history of substance misuse.
INVESTIGATIONS
Toxicology screen may be useful in differentiating causes of altered mental status.
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