subdural hemorrhage

Question 1

definition

Answer 1

Subdural haemorrhages result from rupture of cortical bridging veins. These connect the venous system of the brain to the large intradural venous sinuses and lie relatively unprotected in the subdural space.

Acute subdural haemorrhage is usually associated with severe brain injury following trauma. It can occur at any age

Chronic subdural haemorrhage may be traumatic or may arise spontaneously.

• It is most common in infants and the elderly.
• Blood slowly accumulates in the subdural space, usually overlying the frontal and parietal lobes.
• becomes encysted between an outer wall of highly vascularised, granulation tissue adherent to the dura, and a thinner, inner wall of fibrous tissue. It is frequently bilateral.

Question 2

predisposing factors

Answer 2

Factors predisposing to subdural haemorrhage include:

• any factor that stretches the bridging veins:
• cerebral atrophy, e.g. elderly
• low CSF pressure after shunting, for example for long- standing hydrocephalus or a fistula
• alcoholism
• coagulation disorder or anticoagulation therapy

Question 3

clinical features

Answer 3

The effects develop gradually as bleeding is venous in origin and at low pressure.

General features include:

• fluctuating conscious level:
• there may be a history of gradual onset of headaches, memory loss, personality change, dementia, confusion and drowsiness
• symptoms vary from day to day with intervening lucid periods
• focal neurological signs - often, hemiparesis of the side ipsilateral to the lesion - a “false” localising sign
• aphasia - if the lesion is on the left side

Acute form:

• symptoms follow immediately from an identifiable injury

Chronic form:

• latent period of weeks or months before symptoms apparent
• greater extent of cerebral distortion and herniation than acute form as the brain can initially accommodate the developing mass lesion

Question 4

ix

Answer 4

CT scan is mandatory

• The characteristic picture of a CT scan of a subdural haemorrhage is one of a biconcave, concentric shaped, area of increased density spreading around the surface of the cerebral hemisphere. The contralateral ventricle may dilate owing to obstruction at the foramen of Munro.
• After 10-20 days, the subdural haematoma becomes isodense with brain. Later it becomes relatively hypodense.

A skull X-ray may reveal a fracture.

Question 5

mx

Answer 5

A craniotomy is seldom necessary to treat a subdural haematoma.

Management depends upon the age of the patient.

In infants:

• evacuate haematoma through the anterior fontanelle by repeated needle aspiration
• subdural peritoneal shunt for persistent subdural collections

In adults:

• patients in whom conscious level is depressed:
• evacuate haematoma through 2-3 burr holes, and irrigate cavity with saline
• nursing in the head down position is recommended to prevent recollection
• patients in whom conscious level is not depressed:
• consider conservative measures - steroid treatment over several weeks

Question 6

ddx

Answer 6

• evolving stroke - but focal deficits are more prominent than the presence of drowsiness
• dementia
• intracranial tumour
• depression