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Scope: mBIG applies ONLY to traumatic intracranial hemorrhage in adults with mild traumatic brain injury (GCS 13–15). It is not applicable to spontaneous/aneurysmal subarachnoid hemorrhage, spontaneous intracerebral hemorrhage, or any non-traumatic intracranial hemorrhage.

mBIG 1 (lowest risk)

All of the following must be true:

• GCS 15
• No loss of consciousness (LOC)
• No seizure
• No emesis
• Isolated SDH ≤4 mm, isolated EDH ≤4 mm, isolated tSAH ≤4 mm, cerebral contusion ≤2 cm, or intraventricular hemorrhage ≤2 mm
• No herniation or significant mass effect on CT
• Neurologically intact

Disposition: No neurosurgical consultation required; observation in non-monitored setting acceptable; repeat CT imaging not required if clinically stable; may be appropriate for discharge with reliable follow-up.

mBIG 2 (intermediate risk)

Meets any of the following (but does not meet mBIG 3 criteria):

• GCS 13–14, OR
• LOC, OR
• Isolated seizure, OR
• Emesis, OR
• CT findings larger than mBIG 1 thresholds but without herniation/significant mass effect

Disposition: Neurosurgical consultation warranted; admission to step-down or monitored unit; repeat head CT in 4–6 hours or per neurosurgical guidance.

mBIG 3 (highest risk)

Any of the following:

• GCS <13 (note: if GCS <13, patient may not strictly qualify as "mild TBI" — manage per moderate-to-severe traumatic brain injury pathway)
• Any herniation on CT
• Significant mass effect (midline shift >5 mm, cisternal effacement)
• Bilateral or mixed intracranial hemorrhage pattern with neurologic decline
• Neurovascular injury identified

Disposition: Emergent neurosurgical consultation; ICU admission; operative intervention frequently required.