The patient is a ten year old boy who presented with a painful, discolored swelling behind his left ear. He said the swelling had increased noticeably in size over the previous 6 months.

The swollen area, upon physical examination, proved to be a pulsatile mass, with some reddish discoloration. (Figure 1A) The results of MRI/MRA imaging was consistent with an extra-cranial AVM, with feeders from the anterior and posterior auricular branches. There was suggestion of feeders from branches of the middle meningeal artery.

Selective angiogram confirmed feeders from the anterior and posterior auricular arteries. (Figure 2A) Super selective embolization was performed of feeders involved in the auricular cascade with penetration into the draining veins, nidus, and distal dedicated feeding arteries. Concurrently, the ear was packed in ice to stop flow to the normal tissue. One-tenth of a cc of non-opacitied NBCA was used to minimize the mass of embolic material and discoloration. This led to the total obliteration of the AVM.

Follow-up, (Figure 2B) shows obliteration of the AV shunting. Additional angiography is indicated in 6-12 months to confirm obliteration.
Figure 1A Posterior aspect of Left Ear. 
Figure 1B Two weeks after embolization the inflammation is gone and the shunt gone by Doppler.
Figure 2A PA view of Left External Carotid Angiogram showing  posterior and anterior Auricular Arteries in ear, helix and scapha feeding with a dominate fistula.
Figure 2B Total angiographic obliteration of AVM and fistula with sparing of the Helix cascade( as seen on late films)
KEY LEARNING POINTS:
  1. Extra-cranial AVMs can become quite active, and can grow with trauma, puberty, or pregnancy.
  2. Normal tissue blood flow is controlled by tissue temperature, whereas pathological shunts seen in AVM’s are fixed. At temperatures below 20C, there is virtually no flow to normal tissue. It is possible to take advantage of this to spare the normal tissue and target the shunts as in this case.
  3. Angiographic follow-up is needed in all AVM treated cases once the non-invasive imaging has been negative for 6-12 months as it is the only way to confirm cure.
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