Subdural haematoma

Question 1

What is a subdural haematoma?

Answer 1

collection of venous blood accumulating in the potential space between the dura mater and arachnoid mater

Question 2

In which patients do subdural haemorhhages typically occur?

Answer 2

elderly patients following minor trauma

Question 3

What is the aetiology of subdural haematomas?

Answer 3

minor trauma results in shearing forces that tear bridging veins between the cortex and dura mater

Question 4

What are 4 risk factors for subdural haemorrhage?

Answer 4

1. Advancing age (>65)
2. Bleeding disorders or anticoagulant therapy
3. Chronic alcohol use
4. Recent trauma

Question 5

What are the 3 classes that subdural haemorrhage can be grouped into?

Answer 5

1. Acute
2. Subacute
3. Chronic

Question 6

Within what time frame does chronic SDH occur?

Answer 6

>3 weeks

Question 7

Within what time frame does sub-acute SDH occur?

Answer 7

3 days to 3 weeks

Question 8

Within what time frame does acute subdural haematoma occur?

Answer 8

<3 days

Question 9

What is an acute subdural haematoma?

Answer 9

collection of fresh blood within the subdural space, most commonly caused by high impact trauma

Question 10

What is often associated with acute subdural haematoma and why?

Answer 10

other underlying brain injuries, because it is associated with high-impact injuries

Question 11

What is the presentation of acute subdural haematoma?

Answer 11

spectrum of severity depending on size/ associated injuries; ranges from incidental finding in trauma to severe coma and coning due to herniation

Question 12

What is the first line investigation for subdural haematoma?

Answer 12

CT imaging

Question 13

What is the finding of subdural haematoma on CT?

Answer 13

crescenteric collection (banana), hyperdense compared with brain, not limited by suture lines

Question 14

How does CT scan appearance of SDH vary depending on hyperacute vs acute vs subacute vs chronic phase?

Answer 14

• hyperacute (<1 hr): clot may appear as relatively isodense with underlying cerebral oedema
• acute (<3 days): crescent shaped homogeneous hyperdense extra-axial collection over affected hemisphere
• sub-acute (3 days to 3 weeks): organisation of clot, density falls so appears more isodense. mass effect, sulcal effacement
• chronic (>3 weeks): haematoma becomes hypodense relatie to adjance cortex

Question 15

In what proportion of adults are SDH bilateral?

Answer 15

15%

Question 16

In what proportion of children are SDH bilateral?

Answer 16

80%

Question 17

How often do patients present in the hyper-acute (<1 hour) phase of SDH?

Answer 17

rarely

Question 18

What can aid identification of the SDH in the sub-acute phase (3 days to 3 weeks) when the density of the close is more isodense?

Answer 18

contrast-enhanced CT or MRI

Question 19

How can small or incidental acute subdurals be managed?

Answer 19

observed conservatively

Question 20

What is the management of larger acute subdural haemorrhages?

Answer 20

surgical: monitoring of ICP, decompressive craniectomy

Question 21

What is a chronic subdural haematoma?

Answer 21

collection of blood within the subdural space that has been present for weeks to months

Question 22

How do chronic subdural haemorrhages typically form?

Answer 22

rupture of small bridging veins wihtin the subdural space causes slow bleeding - elderly and alcoholic patients particularly at risk of subdural haematomas due to atrophy and therefore taut or fragile bridging veins

Question 23

Which patients are at particular risk of chronic subdural haemorrhage and why?

Answer 23

Elderly and alcoholic patients are particularly at risk of subdural haematomas since they have brain atrophy and therefore fragile or taut bridging veins

Question 24

What is the typical presentation of a chronic subdural haematoma?

Answer 24

several week to month progressive history of either confusion, reduced consciousness or neurological deficit

Question 25

In what syndrome can infants be affected by subdural haemorrhage? Why does this occur?

Answer 25

shaken baby syndrome - due to fragile bridging veins which can rupture

Question 26

How does the appearance of acute vs chronic subdural haemorrhages vary?

Answer 26

will appear hypodense i.e. dark in chronic, white in acute i.e. hyperdense

Question 27

What is the management of small or incidental subdural haematomas?

Answer 27

conservatively, with hope will dissolve with time

Question 28

What is the management of chronic subdural with confusion or neurological deficit?

Answer 28

surgical decompression with burr holes