1.5 Stereotactic Brain Biopsy and Antiplatelets

Question 1

A 64-year-old man is scheduled for a stereotactic brain biopsy. He is taking dual antiplatelet therapy
following the insertion of a drug-eluting coronary artery stent six months earlier.

a) Explain the issues that may arise from antiplatelet therapy in this patient. (30%)

Answer 1

1. Bleeding
   If dual antiplatelet therapy (DAPT) continues,
   the patient is at very high risk
   of bleeding as a result of the biopsy,
   into a closed skull,
   without access for diathermy,

with consequent pressure damage on surrounding structures causing brain damage,
obstruction of CSF drainage and seizures.

Even aspirin alone is associated
with a significantly increased mortality risk in
neurosurgery.

Excessive bleeding from the scalp may occur,
but this is unlikely to be a significant issue

2. ISR
   Premature cessation of DAPT renders patient at significant risk of in-stent thrombosis, which carries a mortality of about 50%.
3. ADP Rebound**
   Cessation of ADP receptor antagonist
   may be associated with a rebound phenomenon,
   which,
   in association with the stress
   response to surgery,

may render the patient at even
higher risk of thrombosis than usual
in the perioperative period.

Question 2

b) Summarise the perioperative strategies to minimise the above issues. (40%)

Answer 2

Multidisciplinary decision:
cardiologist, anaesthetist, surgeon, patient.

The decision needs to balance the risks of premature cessation of DAPT against the urgency of the biopsy.

DAPT usually continues for one year after
insertion of a drug-eluting stent (DES) but factors that may increase the risk of in-stent thrombosis and therefore mandate more prolonged DAPT include
impaired renal function, ejection fraction <30%, multiple overlapping stents, stents at bifurcations, diabetes mellitus.

Options:
1. Delay
» Delay biopsy until planned time for DAPT has finished. Although one year is usually the minimum duration for DAPT after DES, the risk of in-stent
thrombosis decreases after six months. This is only an option if the indication for biopsy is not unduly urgent.

2. Stop 1
   &raquo_space; Stop ADP receptor antagonist for an appropriate duration prior to surgery but, ideally, continue aspirin if the surgeon and cardiologist are in agreement that the risk of stopping the aspirin outweighs risk of continuing (although the surgeon is unlikely to proceed with biopsy with ongoing aspirin).
3. Stop Both
   » Stop both ADP receptor antagonist and aspirin (a week) prior to surgery if the surgeon and cardiologist are in agreement that the risks of bleeding outweigh the risk of in-stent thrombosis.
   Restart aspirin as soon as possible after surgery.
4. Bridging
   » Consideration of bridging with a short-acting GP IIb/IIIa inhibitor, starting within 24 hours of stopping ADP receptor blocker, restarting after surgery
   and then restarting ADP receptor antagonist the day after surgery if satisfied with haemostasis. This is not, however, a licenced indication for use of this drug.
5. Interventional Cardiology
   » If the patient is deemed at high risk of in-stent thrombosis and the ADP receptor antagonist +/− aspirin are to be discontinued, consideration should be given to performing the biopsy in a centre with on-site 24-hour interventional cardiology support to attempt to mitigate the severity of any thrombosis that occurs.

Question 3

c) What are the specific contraindications (15%) of a stereotactic brain biopsy under sedation?

Answer 3

Contraindications:
» Lesions too small to safely target.

> > Coagulopathic patient.

> > Highly vascular tumour or lesions that could possibly be vascular malformations.

> > Patient conditions causing inability to comply with procedure (difficulties communicating, confusion, movement disorders).

Question 4

What are the specific complications (15%) of a stereotactic brain biopsy under sedation?

Answer 4

Complications:
» Haemorrhage
(and no direct access to the site for diathermy).

> > Airway compromise in awake or asleep patient with poor access to airway due to frame (if being used).

> > Air embolism.

> > Failure to obtain diagnostic specimen.

> > Seizure.

> > CNS infection.