Introduction
Cerebral Angiogram is a method of evaluating the blood vessels in the head and neck. It uses digital subtraction angiography technique which requires x-rays to capture images of body structures with and without contrast injection. This allows the background bony structures to be removed electronically from the image or ‘subtracted’, thereby only showing the blood vessels marked by the contrast dye.
Cerebral angiogram is a catheter-based procedure, usually done through the femoral artery in the groin. Although it is slightly invasive, it remains the gold-standard imaging modality for assessing certain conditions, particularly neurovascular conditions, such as aneurysms, brain AVMs, dural arteriovenous fistulas and carotid-cavernous fistulas. The main advantage is that it gives real-time, clear, high-resolution images, similar to a movie, of how blood travels throughout the brain. In contrast, CTA and MRA are analogous to a photograph, which provides static snapshots of the blood vessels.
Indications
There are many reasons for performing cerebral angiogram, but the main indications are for evaluation and treatment planning of:
- Brain aneurysms.
- Brain arteriovenous malformation.
- Strokes.
- Carotid and vertebral artery stenosis and / or occlusion.
- Dural arteriovenous fistula and carotid-cavernous fistula.
- Blood supply to a tumour.
Preoperative Instructions
Before all neurosurgical procedures, including this procedure, you should…
- Be ‘Nil by mouth’ with no oral intake before midnight the night before the procedure Medications can be taken with very small sips of water.
- Inform us if you take blood thinners. Some types of blood thinners are permitted, so please consult your doctor about whether your blood thinners may need to stopped ahead of the procedure.
- Please bring all scans and imaging with you on the day of the procedure.
- Notify our office if you develop any symptoms of infection, e.g. a cold or flu, before surgery, or if you are receiving treatment for an infection, so that we minimise the risks of having a peri-procedural infection.
Procedure
The patient usually remains awake with sedation during this procedure with local anaesthesia administered into the groin. While the patient is lying on their back on the operating table, a small needle (‘micropuncture’) is used to gain access in the femoral artery in the groin with ultrasound guidance. This is then replaced with a small plastic tube (‘sheath’), which acts as an entry point for the catheter.
The catheter (a plastic angled tube) is carefully maneouvered through the aorta and into the desired neck arteries (carotid and vertebral arteries). Once the catheter is positioned, the patient is asked to hold their breaths while contrast dye is injected. Angiography produces a video or sequence of pictures as the dye moves through the blood vessels in the brain. Hence, it is important for patients to remain still for 20-30 seconds while the pictures are being taken from each injection. As the contrast dye travels through the blood vessels, there may be sensations of ‘flashing lights in the eyes’, ‘flushing in the face’, or ‘dizziness’ at the back of the head.
Cerebral angiography takes about 30-45 minutes to complete, after which the catheter is removed. A closure device, or internal suture / ‘stitch’, is used to close the opening in the groin artery once the sheath is removed. Sometimes, additional pressure on the arterial opening is required over 10-15 minutes to ensure no further bleeding occurs from the entry site.
Postoperative Instructions
Patients are generally kept for observation in recovery for 3-4 hours, during which time, the leg is kept straight. The patient can return home the same day, and can often return to normal day-to-day activities within a few days. Swimming is avoided for the first week.
Risks
Cerebral angiogram is a reasonably safe procedure. It has less than 1% risk of complications overall. Potential risks include…
- Bleeding from artery at groin insertion point.
- Infection (usually at the groin).
- Stroke (resulting in temporary or permanent weakness, numbness, vision and speech disturbance) – occurs less than 1 in 500-1000.
- Damage / dissection of blood vessels leading to additional repair procedures.
- Damage to kidney function as the contrast dye is removed by kidneys.
- Allergic reaction to contrast agent.
Treatment Alternatives
Non-invasive neuroimaging, e.g. CTA (Computer tomography angiography) or MRA (magnetic resonance angiography).