Subdural haemorrhage

Bleeding into the space between the outer and middle layers of the meninges, usually following head injury. The trapped blood slowly forms a large clot within the skull that presses on brain tissue. The symptoms, which tend to fluctuate, may include headache, confusion, drowsiness, and one-sided weakness or paralysis. The interval between the injury and the start of symptoms varies from days to months. Diagnosis is by CT scanning or MRI. In many cases, surgical treatment is needed. This involves drilling burr holes in the skull (see craniotomy), so that the blood can be drained out and damaged blood vessels repaired. If treatment is carried out at an early enough stage, the person usually makes a full recovery. A subdural haemorrhage that is small and produces few symptoms may not require any treatment. The affected person is usually monitored with regular scans, and the clot may clear up on its own. (See also extradural haemorrhage.)