subarachnoid hemorrhage

Question 1

define

Answer 1

spontaneous bleeding into subarachnoid space

Question 2

epidemiology

Answer 2

9/100,000/yr

typical age: 35-65yo

Question 3

Causes

Answer 3

• 85% are due to rupture of berry aneurysms (conditions associated with berry aneurysms include adult polycystic kidney disease, Ehlers-Danlos syndrome and coarctation of the aorta)
• AV malformations
• trauma
• tumours

Question 4

RFs

Answer 4

Smoking

• HTN
• EtOH
• Bleeding diathesis
• Mycotic aneurysms (SBE)
• post-menopausal: ↓oestrogen >45: W>M 3:2
• Fx: close relatives have 3-5x risk

Question 5

Investigations

Answer 5

CT: negative in 5%

• Detects >90% of SAH w/i first 48hrs

lumbar puncture:

• If CT-ve and no CIs >12h after start of headache

done after 12 hrs (allowing time for xanthochromia to develop -due to breakdown of bilirubin (confirms that it is SAH and not bloody tap)

Question 6

Management

Answer 6

The principles of nursing care for subarachnoid haemorrhage are:

• continuous observation
• intravenous access
• headache may be relieved with mild analgesics, e.g. paracetamol or codeine. Aspirin must be avoided.
• keep stools soft by administering oral laxatives and ensuring an adequate fluid intake other than milk.
• short-acting benzodiazepines to alleviate distress.

prevention of delayed cerebral ischaemia

• Nimodipine, in a dose of 60 mg orally every 4 hours or by nasogastric tube, reduced the incidence of cerebral ischaemia by one third
• Hypertension during the acute stage should generally be left untreated as it is probably a compensatory response to maintain cerebral perfusion.
• Plasma volume must be maintained - at least 3 litres of fluid per day with iv fluids to supplement oral intake.

prevention of rebleeding

• At least 10% of all patients with SAH have another bleed within hours of the initial one. Without intervention, rebleeding occurs in at least 30% of cases in the subsequent 4 weeks. The immediate mortality of rebleeding is 50%.
• Prevention may be:
• surgical - by clipping the aneurysm. Improvements in technique have greatly reduced the risk of post- operative cerebral ischaemia. The greatest benefits of surgery are thought to occur after 11-14 days.

Question 7

s/s

Answer 7

Symptoms

 Sudden, severe occipital headache
 Collapse
 Meningism: neck stiffness, n/v, photophobia
 Seizures
 Drowsiness → coma (days)

Signs

1. subhyaloid haemorrhage –bleeding btw retinaand vitreousmembrane
2. Neck stiffness
3. Kernig’s sign (after 6h)

• a diagnostic sign for meningitis marked by a loss of the ability of a supine patient to completely straighten the leg when it is fully flexed at the knee and hip.
• Pain in the lower back and resistance to straightening the leg constitutes a positive Kernig’s sign.

4. Terson’s syndrome: Retinal or subhyaloid and vitreous bleeding (funduscopy)

5.Focal neuro
o @ presentation suggests aneurysm location
o Later deficits suggest complications

6.Sentinel Headache
 ~6% of pts. experience sentinel headache from small warning bleed.

Mortality in SAH:

Question 8

complications

Answer 8

1. death - 50% in first 30 days, many before reaching hospital
2. decreased level of consciousness -
   
   1. sudden causes include rebleeding, epilepsy, and ischaemia;
   2. a gradual onset suggests ischaemia, hydrocephalus and metabolic dysfunction
3. rebleed - in the absence of intervention,
   
   1. 10% rebleed within hours,
   2. 30% within 4 weeks, and
   3. 50% within 6 months.
   4. Apnoea occurs in 30% of all cases.
   5. Assisted ventilation restores spontaneous respiration in most cases.
   6. Emergency clipping is advised.
4. cerebral ischaemia - usually insidious and multifocal or diffuse. The level of consciousness falls in 75% of cases, with focal neurological signs in 50%. Cerebral perfusion must be increased by expanding plasma volume and/or inducing hypertension with dopamine or dobutamine. Transluminal angioplasty is rarely performed because of the associated risks.
5. acute hydrocephalus -
   
   1. in 15-20% of cases, usually within the first few days.
   2. Gradual obtundation is suggestive.
   3. Spontaneous improvement within 24 hours occurs in 50% of cases in the absence of massive intraventricular haemorrhage.
   4. An external ventricular catheter may be beneficial but at the cost of an increased risk of rebleeding.
   5. Lumbar puncture may obviate the need for a shunt if the obstruction lies in the subarachnoid space rather than the ventricular system.
6. rarely, myocardial infarction, pulmonary oedema, and gastric haemorrhage.

Question 9

differential diagnosis of subarachnoid haemorrhage is:

Answer 9

severe migraine

acute meningitis

post-coital cephalgia