There are 3 classification system for subdural hematoma. Subdural hematoma may be classified according to symptom onset and duration into 3 subtypes including acute, subacute, and chronic, according to midline shift and thickness into 4 subtypes, and based on imaging findings into 6 subtypes.

There are 3 classification system for subdural hematoma:^[1][2]

• Subdural hematoma may be classified according to symptom onset and duration into 3 subtypes:
  • Acute: Develop less than 24 hours after head trauma (or other subdural hemorrhage causes)
  • Subacute: Develop between 1 to 10 days after head trauma (or other subdural hemorrhage causes)
  • Chronic: Develop weeks or months after head trauma (or other subdural hemorrhage causes). It can be further divided into 5 grads:
    • Grade 0: Normal patient with no symptom
    • Grade 1: Patient has headache and mild or no neurological abnormalities but is alert
    • Grade 2: Decreased level of consciousness (drowsiness) with neurological abnormalities
    • Grade 3: Sever focal neurological deficit and loss of consciousness but response to pain stimuli
    • Grade 4: Coma with no response to pain stimuli
• Subdural hematoma may be classified according to mid-line shift and thickness into 4 sub-types:
  • Type A: Thickness ≤ 1cm, midline shift ≤ 5 cm
  • Type B: Thickness > 1cm, midline shift ≤ 5 cm
  • Type C: Thickness > 1cm, midline shift > 5 cm
  • Type D: Thickness ≤ 1cm, midline shift > 5 cm
• Subdural hematoma may be classified according to imaging findings into 6 subtypes:
  • Type 1: Hyperdense lesion, relatively homogeneous (describes acute subdural hemorrhages)
  • Type 2: Isodense lesion, relatively homogeneous (describes subacute hemorrhages)
  • Type 3: Hypodense, relatively homogeneous (describes chronic hemorrhages)
  • Type 4: Isodense to hypodense, relatively heterogeneous (describes recent rebleeding)
  • Type 5: Hypodense in its liquefied component, relatively heterogeneous; internal septations and loculations (higher risk for recurrence after surgical treatment)
  • Type 6: Calcified hyperdense, relatively homogeneous (describes subdural hemorrhage with calcified component)