Posterior Auricular Artery-Middle Cerebral Artery Bypass: A Rare Superficial Temporal Artery Variant with Well-developed Posterior Auricular Artery–Case Report

Abstract

The posterior auricular artery (PAA) is one of the branches of the external carotid artery, but is usually too small for use as a donor artery for middle cerebral artery (MCA) territory revascularization. An extremely unusual case of PAA-MCA anastomosis was performed in a patient requiring MCA territory revascularization because the superficial temporal artery (STA) parietal branch was absent and the PAA was large enough. A 65-year-old man developed mild motor weakness in the right extremities caused by multiple small infarctions. Single photon emission computed tomography (CT) revealed deterioration of the vascular reserve capacity in the left MCA area. Cerebral angiography showed severe stenosis in the C2 portion of the left internal carotid artery, absence of the parietal branch of the left STA, and a well-developed PAA extending to the parietal area. The patient underwent STA (frontal branch)-MCA and PAA-MCA double anastomosis, and has suffered no stroke or transient ischemic attack. The STA with no bifurcation is known as a rare variation. The PAA also occurs with size variations but well-developed PAA is thought to be extremely rare. PAA can be used as a donor artery for MCA territory revascularization if the vessel size is suitable. Preoperative evaluation of the anatomy is mandatory for harvesting the arteries.

Posterior auricular artery as an alternative donor vessel for extracranial-intracranial bypass surgery

“…Recently, the PAA was used as a donor artery for additional revascularisation in a patient with a refractory case of moyamoya disease despite direct STA and occipital artery bypasses [8]. Another case report [16] describes the use of the PAA for a double-barrel revascularisation procedure, which is comparable to our second case. Our report adds three additional PAA to MCA bypasses, and by describing perioperative flow dynamics and long-term postoperative imaging in one patient, we show that the PAA can be as patent as the STA [10] and therefore could be a reliable alternative.…”

“…Sometimes the STA is not available for bypass surgery due to hypoplasia of the artery, division of the artery at previous craniotomy, damage of the artery during dissection, or it is already used for an intracranial bypass. In such cases, the PAA can be used as an alternative donor when it ascends to the temporoparietal area with a large enough diameter [8,16].…”

“…Our literature search resulted in three hits, of which one article was not relevant to the topic. The selected articles have both recently been published in neurosurgical journals and described a bypass of the PAA to the MCA [8,16]. An overview of the reported data, added with the data of the current report, is presented in Table 1.…”

“…An alternative method is connecting the external carotid artery (ECA) with an interposition graft (saphenous vein or radial artery) to the intracranial internal carotid artery (ICA) or MCA, which is mostly used for high-flow bypasses [3]. Other, rarely used, donor arteries are the occipital artery [7,12] or the posterior auricular artery (PAA) [8,16].…”

“…In these cases an interposition graft can be used as an alternative, but this technique has its risks and drawbacks [3]. Recently, the PAA w a su s e da sa na d d i t i o n a lb y p a s si nar e f r a c t o r yc a s eo f moyamoya disease [8]a n df o rar e v a s c u l a r i s a t i o np r o c edure [16], indicating that the PAA might be a potential candidate for a EC-IC bypass.…”