Possible Elana Locations
The ELANA technique involves a platinum ring. A 2.6 and a 2.8 mm ring are enclosed in the Elana Surgical Kit(HUD). Therefore, the smallest possible recipient artery has a diameter of approximately 2.5 mm. Smaller arteries than this size are more peripheral in the brain. They tolerate temporary occlusion time because of intracerebral and leptomeningeal collaterals (these are ‘natural’ bypasses already existing in the human brain). Therefore on these vessels a conventional anastomosis instead of an ELANA is possible.
The below picture indicates the possible ELANA anastomosis locations in the brain.
The ELANA site has to be free of arteriosclerotic plaques or any other vessel wall disease.
Figure 1: Schematic overview of the proximal arterial vasculature of the brain. Possible area for an ELANA anastomosis is indicated in blue. Abbreviations (left to right, top-down): RMCA, Right Middle Cerebral Artery; RACA, Right Anterior Cerebral Artery; LACA, Left Anterior Cerebral Artery; LMCA, Left Middle Cerebral Artery; PCOMS, Posterior Communicating Arteries; RPCA, Right Posterior Cerebral Artery; LPCA, Left Posterior Cerebral Artery; RICA, Right Internal Carotid Artery; BA, Basilar Artery; LICA, Left Internal Carotid Artery; RCCA, Right Common Carotid Artery; RVA, Right Vertebral Artery; LVA, Left Vertebral Artery; LCCA, Left Common Carotid Artery.
Possible Elana bypasses
With the ELANA technique, a whole new spectrum of possible bypasses opens up in vascular neurosurgery. Because of the different possible proximal locations it can facilitate a high flow in the original direction of the bloodflow.
Extra-Intracranial High-Flow Bypass
As a proximal, extracranial anastomosis site the external carotid artery (ECA) or the superficial temporal artery (STA) can be chosen. This is preformed in a conventional way because, except from a small group of patients with an occluded ICA and collateral ophthalmic flow, patients tolerate temporary occlusion time in these regions. The distal anastomosis can be made in any area suitable for ELANA.
Schematic overview of an extra-intracranial bypass from the ECA to the ICA (left and the STA to the ICA (right). The bypass conduit can be constructed behind or in front of the ear. Indications could be giant ICA aneurysm, an occluded ICA or skull base tumors(see ‘indications’ under ). Recently a mean postoperative flow of 156 cc/min was reported through these kind of ELANA Ec-Ic bypasses.
Intra-Intracranial High-Flow Bypass
The ELANA can also be used for Ic-Ic bypass grafting for more peripheral pathology. Depending on recipient size, degree of arteriosclerosis and if the site is surgical reachable, a proximal and distal ELANA or only a proximal ELANA can be perormed. Examples are shown below in figure 3:
Left: Ic-Ic bypass from the ICA bifurcation (ELANA) to an M3 branch of the MCA (conventional). Note that if an M2 branch is reachable with a minimal diameter of 2.5 mm without arteriosclerosis, an ELANA would be preferable. Mean flow of 53 cc/min was recently reported through these ELANA bypasses. Middle: Ic-Ic bypass from the ICA bifurcation (ELANA) to a right A3 branch (Conventional). Right: Ic-Ic bypass with a proximal (ICA) and distal (P1 part of PCA) ELANA anatomosis.