Makindo Medical Notes

Related Subjects: |Subdural haematoma

A subdural hematoma (SDH) is an accumulation of blood between the dura mater and the arachnoid membrane, usually related to trauma or anticoagulation. It can be bilateral and is often associated with head trauma. It's essential to rule out associated C-spine fractures in trauma cases.

Mechanism

• Caused by a tear in bridging veins, usually due to acceleration-deceleration injuries.
• Common cause of altered mental status, ranging from delirium to coma.
• CT head and cervical spine are essential in evaluating suspected cases.

Top Tips

• Subdural blood can sometimes be isodense to brain parenchyma and may be missed on imaging.
• Neurosurgeons may prefer to allow the blood to liquefy before removing it through burr holes.

Aetiology

• Rupture of bridging veins crossing the subdural space.
• Worsens with cerebral atrophy due to increased shear forces.
• Head injury is the most common cause; the trauma may be subtle or not recalled by the patient.
• Chronic alcohol abuse and anticoagulant therapy increase the risk.
• Increased intracranial pressure (ICP) can compress the thalamus and brainstem, leading to further complications.

Causes

• Falls and trauma, especially in the elderly.
• Anticoagulant therapy, alcohol abuse, and assaults.
• Low CSF pressure, which may occur after a lumbar puncture.

Clinical Features

• Can present acutely with a rapid drop in GCS or chronically with subtle symptoms such as delirium or confusion.
• Headache, unsteadiness, contralateral hemiparesis, or hemisensory loss.
• Fixed dilated pupil and IIIrd nerve palsy may indicate herniation.
• Seizures, drowsiness, delirium, or a gradual decline in consciousness.
• Cheyne-Stokes respiration, reduced GCS, and signs of raised ICP may be present in severe cases.

Imaging Examples

Large Left Subacute SDH with Midline Shift

Large Left Acute SDH with Midline Shift

Investigations

• Coagulation Screen: Check INR, particularly if the patient is on Warfarin or has liver disease.
• Non-contrast CT Scan: Demonstrates a crescent-shaped extra-axial blood collection. Over time, the hematoma may change density, becoming isodense to brain tissue and later similar to CSF. Look for midline shift and signs of raised ICP.
• CT Cervical Spine: Required if there are concerns about a spinal fracture, particularly in unconscious patients.
• MRI Scan: Useful when a subdural hematoma is isodense with the brain on CT.

Complications

• Recurrent hematomas.
• Infection, such as subdural empyema.
• Seizures, often focal and contralateral initially.
• Raised intracranial pressure (ICP) and brain herniation.
• Contralateral anterior cerebral artery (ACA) stroke due to arterial compression by the falx.

Management

• Acute Management: ABCs, urgent neurosurgical referral, and reversal of any coagulopathy. Platelet count should be maintained above 100 × 10⁹/L.
• Anticonvulsants: May be initiated acutely, particularly in patients with seizures.
• Neurosurgical Intervention:
  • Small subdural hematomas may be managed conservatively.
  • Larger hematomas often require surgical evacuation via trauma craniotomy or burr holes.
  • For chronic SDH, burr holes are typically preferred once the clot has liquefied for easier aspiration.
• Chronic SDH: Usually managed with burr holes due to the jelly-like consistency of the clot. Recommendations suggest evacuating hematomas larger than 10 mm or those causing a midline shift greater than 5 mm.
• Palliative Care: In some cases, especially with frail patients and signs of raised ICP, palliative management may be appropriate.