subdural

Subdural refers to the region beneath the dura mater, the brain's outer protective layer. The subdural space is a potential space between dura and arachnoid membranes. Normally it is minimal, but it can widen with fluid or blood following injury or disease. The term most often appears in reference to subdural hematoma, bleeding into this space after tearing of bridging veins.

Subdural hematoma: This condition occurs when blood accumulates between dura and arachnoid. It is commonly caused by head trauma but can occur with minor injuries in the elderly or in people taking anticoagulants. Bleeding may be acute, subacute, or chronic, depending on onset and rate of accumulation.

Symptoms: Headache, confusion, drowsiness, and focal neurological deficits such as weakness or language disturbance. Acute cases can progress rapidly and lead to decreased consciousness.

Diagnosis: Noncontrast CT is the initial test. Acute hematomas appear hyperdense on CT, subacute lesions may be isodense, and chronic ones are often hypodense. MRI can be helpful if CT findings are unclear.

Treatment: The approach depends on size and symptoms. Acute subdural hematomas usually require surgery to evacuate the blood (burr hole or craniotomy). Small, asymptomatic chronic hematomas may be observed, while symptomatic or enlarging chronic hematomas are often drained. Reversal of anticoagulation may be needed.

Related conditions: Subdural hygroma is a collection of cerebrospinal fluid in the subdural space, often after trauma or surgery. It may resolve spontaneously but can require drainage if symptomatic.