Spinal Cord Embolisation (AVM/DAVF)

Author: Dr Winston Chong*

What are the prerequisites for having a Spinal Cord Embolisation (AVM/DAVF) done?

The patient will need:

• FBE
• U&E
• Clotting Profile (INR & APPT)
• Group and Hold (in case transfusion is needed)
• Thyroid function test if indicated (see “Relative Contraindications”, below)
• Exclude pregnancy
• Any relevant previous imaging tests. As a minimum there should be a recent MRI. Other preliminary tests such as angiogram should be discussed with the interventional neuroradiologist.

The patient should have a preliminary consent discussion with the referring doctor (if the referrer is also the treating neurosurgeon) as to what the condition means and in general what are the treatment options. If the referrer is not the treating neurosurgeon, then the patient should be referred to one.

A letter or request for the embolisation procedure. Relevant clinical details of the patient including pre existing significant medical and surgical conditions should be provided to the interventional neuroradiologist. The treating neurosurgeon and the interventional neuroradiologist need to discuss the case beforehand.

In general, clopidogrel should be stopped prior to the procedure if possible. Patients on warfarin should have this stopped and be changed over to heparin. The heparin then needs to be stopped 24 hours prior to the procedure.

What are the absolute contraindications for a Spinal Cord Embolisation (AVM/DAVF)?

Very large body habitus well beyond the weight limit of the angiographic suite. This depends on the machine but is generally from 120 kilos to 200 kilos. Consult with radiologist.

A large amount of spinal metallic hardware can totally obscure X-ray penetration and may make the procedure impossible.

What are the relative contraindications for a Spinal Cord Embolisation (AVM/DAVF)?

Very large body habitus beyond the weight limit of the angiographic suite. Consult with radiologist.

Severe renal failure not on dialysis. Patients with more mild renal impairment need to be pre-hydrated prior to the procedure. Patients on dialysis can have dialysis session timed to the procedure.

Thyrotoxicosis: This needs to be well controlled as it can be made worse leading to “thyroid storm”, or acute thyrotoxic crisis, due to the iodinated contrast administered during this procedure.

Endocrine and anaesthetic consultations need to be arranged well before hand.

Known allergy to contrast: This requires steroid premedication and the radiologist needs to be advised if the patient has contrast allergy when the procedure is being scheduled. Steroid premedication requires just over 24 hours to administer, i.e. it is not a single dose unless the procedure is being performed as a medical emergency.

Pregnancy: Need to weigh the relative risks of AVM haemorrhage during pregnancy with the risks due to radiation to the foetus (see Radiation Risk of Medical Imaging for Adults and Children).

These foetal risks are mainly cancer induction and developmental malformations and the risk varies greatly with the stage of pregnancy. This requires extensive discussion between the patient and neuroradiologist and the clinical team if the treatment is not an emergency.

Any severe bleeding disorders need to have temporary control of the abnormal clotting profile. Consultation with a haematologist is suggested.

Diseases that can precipitate acute renal failure under heavy contrast media load such as myeloma, severe diabetes, blood dyscrasias, shock, and sepsis need to be notified to the radiologist.

What are the adverse effects of a Spinal Cord Embolisation (AVM/DAVF)?

There is an extremely small risk of serious allergic reaction, death, or brain damage from the general anaesthesia.

Very rarely, there may be internal blood loss requiring open surgery to stitch up the puncture hole in the groin. However, the risk of puncture site haematoma (a semi-solid mass of blood in the tissue) requiring transfusion, surgery or delayed discharge is less than 3%.

The risks directly related to the embolisation procedure itself include stroke and haemorrhage affecting the spinal cord. Very rarely, these can result in death.

The risk of stroke or haemorrhage can vary from low to moderate. The risk can vary from less than 1% to more than 10%. The risk depends on the makeup or configuration (angioarchitecture) of the AVM. It also depends on how much of the AVM is being embolised, i.e. to achieve a cure or a partial embolisation to stabilize the disease or help prepare for proposed open surgery.

The risk cannot be generalised to all patients because AVMs are very different from patient to patient so all of this will be discussed with you before you consent to the procedure.

The effects of a stroke or haemorrhage can vary from complete recovery to permanent problems. These can include paralysis and/or incoordination (inability to coordinate normal movements such as picking up a cup, doing buttons, imbalance walking etc.) of one or more limbs, loss of feeling in the limbs or body, abnormal sensation in the limbs such as tingling or “pins and needles”, or loss of control of the urinary bladder or bowel. If very severe, these can result in death, but this is very rare.

Cord oedema after embolisation can be minimised by corticosteroids.

Are there alternative imaging tests, interventions or surgical procedures to a Spinal Cord Embolisation (AVM/DAVF)?

Options for AVMs are palliative or attempted curative embolisation, AND pre-operative embolisation.

For DAVFs, surgery only.

Useful websites about Spinal Cord Embolisation (AVM/DAVF)

Embolization Treatment for Arteriovenous Malformations (AVMs) of the Brain and Spinal Cord
http://brainavm.oci.utoronto.ca/malformations/embo_treat_avm_index.htm

*The author has no conflict of interest with this topic.

Page last modified on 30/8/2018.