A young man presented with pulsatile swelling of the left pinna, with reddish brown skin discoloration.
He was diagnosed to have arteriovenous malformation and was taken up for  DSA and embolisation under local anesthesia.
DSA showed a high flow AVM with a large fistula. This was then catheterized with a Progreat 2.7 Fr microcatheter, considering the large size of the feeder and the macro-fistula. Embolisation was done with 20% nBCA-lipiodol mixture. Complete exclusion of the AVM was achieved.
There was subsequently blackening of the skin of the earlobe, which necrosed and fell off, it was conservatively managed, with normal smooth skin formation over the ulcerated area and near comparable appearance with the opposite pinna. However there was some redness present in the mid-pinna, which was not explained, and was left behind. This patient is now in follow up since three years.

BACKGROUND AND PURPOSE:

Patients with ruptured brain AVMs are at considerable risk of repeat hemorrhage, particularly when associated intranidal or flow-related aneurysms are present. There is controversy about the timing of diagnosis and treatment of patients with hemorrhagic stroke. We present our results of endovascular treatment of ruptured AVMs in the acute phase.

MATERIALS AND METHODS:

Between January 2008 and March 2011, 23 patients (16 men, 7 women; mean age 42 years) with AVM-related hemorrhagic stroke were treated with endovascular techniques within 10 days of the ictus. There were 10 micro-AVMs (< 1 cm) and 1 single-hole pial fistula. In 9 patients, an intranidal or flow-related aneurysm was the likely cause of hemorrhage.

RESULTS:

Complete obliteration of the AVM with Onyx was achieved in 13 of 23 patients (57%). Eight of the 13 AVMs were micro-AVMs and 3 had an intranidal aneurysm. Partial obliteration of the AVM was achieved in 10 of 23 patients (43%). In 6 of these 10 patients, an intranidal (n = 1) or flow-related aneurysm (n = 5) was obliterated with Onyx or coils. There were no complications of treatment. During a mean follow-up of 21 months in 22 surviving patients, no repeat hemorrhage occurred.

CONCLUSIONS:

Endovascular treatment with Onyx in the acute phase cured most ruptured AVMs. All 9 AVM-associated aneurysms that were considered the source of hemorrhage could be excluded from the circulation. In patients with AVM-related hemorrhagic stroke, prompt angiographic diagnosis and treatment may improve prognosis by reducing repeat hemorrhage rate.

http://www.ajnr.org/content/early/2012/01/26/ajnr.A2995.abstract

Brain AVMs for long had been enigmatic and 'touch me not' lesions, that is until some expert super confident vascular neurosurgeons started operating upon them, and some of them did pretty good job too. Also, radiosurgery ( gamma knife) has excellent results in a large number of these rather badly understood lesions. However, with the advent of smart endovascular neurointerventionists, they also started being treated by embolisation, initially as an adjunct to surgery of radiosurgery, and of late has been propagated as a single modality complete cure, especially with the advent and spread of ONYX.
However, the great interventional neuroradiologists advice a word of caution in following this approah.

Follow this link to see a good commentary by Jayaraman and Cloft.
http://www.ajnr.org/cgi/content/full/30/1/107

jayaraman.png on Aviary.

And here is an excellent reply to the above one from katsaridis
http://www.ajnr.org/cgi/content/full/30/5/e67
katsaridis.png on Aviary.

And here is an excellent comment in AJNR blog by the revered teacher Pearse Morris regarding the same point as Jayaraman.
This comment has incited a fantastic discussion on the above blog page among some of the biggest names in neurointervention.
http://www.ajnrblog.org/2009/02/02/embolization-of-brain-arteriovenous-malformations-for-cure/

pearse morris.png on Aviary.

And here is the link to the original article which started it all: the one by Panagiotopoulos et al
http://www.ajnr.org/cgi/content/short/ajnr.A1314v1
panagiotopoulos.png on Aviary.

What is a cerebral or brain AVM ?
An AVM is a tangle of abnormal and poorly formed blood vessels (arteries and veins) wherein direct connections form between arterial and venous sides without any capillaries in between. Normally arteries take blood away from heart to supply the brain substance after dividing into very tiny structures called capillaries. Veins then take the blood towards heart and then lungs for purification. In AVM the capillaries are missing. AVM can form anywhere in the body.

Fig 1: A- normal Arrangement of blood vessels, B- AVM
Fig 2: AVM in the right frontal lobe of brain. The abnormal bunch of vessels seen in the right upper corner of the image is the AVM.
What causes AVM ?
The cause in unknown and they form during pregnancy in the first trimester while the blood vessels are forming. Only some cases are syndromic and run in families. So far these have not been conclusively found to be associated with any drug intake, infection, pollution etc.
They can occur in people of all races and sexes in almost equal proportions although some reports say they are commoner in males. These are very rare conditions and occur in less than 1% of the population. The typical time of discovery is between the ages of 20 and 40 years although they have been present ever since.
What are the risks from AVM ?
AVMs have a life of there own in a way. They begin, grow and die. In many patients they remain undetected and go to grave with the person. In some, these are picked up during investigations done for other diseases. In a fraction, they produce symptoms.
What are the symptoms of an AVM ?
Haemorrhage (bleeding): AVMs have a higher rate of bleeding than normal vessels. This is the most serious complication of an AVM. The risk of bleeding over one's lifetime may be high especially if the AVM is discovered in a young person.
Table : Risk of Bleeding from an AVM
Life Expectancy from the age of discovery of AVM      Risk of Bleeding
10 years                                                                                            33.5%
20 years                                                                                            55.8%
30 years                                                                                            70.6%
40 years                                                                                           80.3%
50 years                                                                                           86.8%
Bleeding from an AVM will occur in about 4 out of 100 people with a brain AVM every year. Sometimes, a bleed may be small and produce no significant symptoms. Approximately 50% of the bleeds are significant with permanent disability in half of these cases and death in the other half.
Overall about 12% of people harboring an AVM will have symptoms and 1% die.

Fig 3: A -CT scan and B –MRI showing a large area of hemorrhage (white in CT and black in MRI)
Seizures: An AVM in the brain may act as an irritant resulting in seizures.
Headache: Headaches may be caused by the high blood flow through the AVM . These headaches may be similar to a migraine or be actual migraines. They may be mild or quite disabling. Sudden, severe headaches can be caused by bleeding. These headaches are often followed by nausea , vomiting , neurological problems or a decreasing level of consciousness.
Stroke (or stroke-like symptoms): Brain AVMs may cause stroke-like symptoms by depriving the nearby brain of blood as they ‘suck blood’ ( the steal phenomenon).

• Weakness of face or limbs
  
• Numbness and tingling in any part of the body
  
• Vision and hearing disturbances
  
• Memory and personality changes
  

AVM and Pregnancy:
There is an increased risk of haemorrhage from an AVM during pregnancy and delivery due to the increased blood circulation that occurs during pregnancy. Although not all AVMs bleed during pregnancy, it is advisable to cure the AVM before getting pregnant.
How are brain AVM diagnosed ?
A patient undergoing CT scan or MRI of the brain for the above said symptoms or any unrelated condition will be found to have an AVM.

Fig 4: CT scan of the same patient as Fig 2 above showing large blood clot. This scan is non contrast CT and does not show yet the AVM

Fig 5: Plain ( non contrast) CT shows blood clot. After contrast given through intravenous line, CT done again (Contrast CT or CECT as it is called) note many white tortuous snake like structures, this is the AVM.

Fig 6: MRI does not need contrast material to pick up AVM. A is a CECT showing AVM, B is a non-contrast (plain) MRI of another patient showing the AVM. On MRI the blood vessels and hence the AVM appears black.
Following diagnosing the  presence  of an AVM, angiography is done. It can be done with CT (CT angiogram), MRI (MR Angiogram) or DSA ( Digital subtraction angiogram). Of these, DSA is the best technique to evaluate and AVM and will have to be invariably done if definitive treatment is planned in future.
What is the treatment of brain AVM ?

Treatment is offered to  prevent bleeding from the AVM. In other situations a high amount of clinical acumen and precision will be needed to say whether definitive treatment is required or not. e.g if patient is having recurrent seizures or is not responding to oral medications or is having severe headaches clearly attributable to the AVM. Some features of an AVM as seen on DSA also predict high chances of bleeding and these patients will need treatment even if they do not have any symptoms. Also, a clear benefit vs. risk analysis will be done by the treating doctor before offering any treatment.

Embolization
Under general anaesthesia a small catheter (plastic tube) is advanced from an artery of the groin, into the brain vessels and then into the AVM. A liquid material called ‘glue’ (chemical name n-Butylcyanoacrylate or nBCA) is injected into the AVM to form a solid cast and exclude any blood flow to the AVM.  Now another liquid material called ONYX is also available which has been claimed to produce better chance of complete AVM cure. There is a small risk to this procedure and the chances of completely curing the AVM using this technique depends on the size of the AVM and some other features as seen on DSA. Upto 45- 50% chance of complete cure is possible with embolization. Multiple sittings may be required.

Fig : Figures on left of screen show DSA images before and after embolization. there is near complete cure of AVM however a small portion remained. There was haemorrhage, unfortunately after the procedure, so the patient underwent surgery to remove the blood clot and the remaining portions of the AVM. A DSA was done after few months which showed complete cure of the AVM. The bottom image shows the ‘cast’ of the glue.

Radiation Treatment
This treatment is also known as Radiosurgery or Stereotactic Radiotherapy or Gamma knife therapy. A narrow  radiation beam of high dose is focused on the AVM. This radiation causes the AVM to shrink and eventually disappear over a period of 2-3 years in up to 80% of patients. The risk of complications is low. Until the AVM is completely eradicated, the risk of bleeding still persists however.

Surgery
The AVM is surgically removed in an operating room under general anaesthesia after opening the skull. Since AVMs do not grow back, the cure is immediate and permanent if the AVM is removed completely. The risks of surgery are considered to be high for AVMs that are located in deep parts of the brain with very important functions. If the AVM has bled then surgery can be done to remove the blood clot and in the same sitting the AVM can also be taken out. In many instances, embolization is done prior to surgery to reduce the size of the AVM or to tackle the very weak areas of the AVM which can bleed by handling during surgery.