Less invasive bonnet bypass with subcutaneous tunneling method for common carotid artery occlusion - A technical note.

Background: Common carotid artery occlusion (CCAO) sometimes requires vascular reconstruction. Ipsilateral superficial temporal artery (STA)-middle cerebral artery (MCA) bypass is unsuitable due to insufficient blood flow to the external carotid artery. The bonnet bypass, one treatment option for CCAO, requires a long coronal incision and bone groove to prevent malposition and collapse of an interposition graft. However, this long incision might lead to skin complications and reduced collateral blood flow.

Methods: A 60-year-old man who experienced recurrent ischemic stroke presented with the right internal carotid artery occlusion and left CCAO. The left STA was unavailable; however, both branches of his right STA were well-developed. Minimizing skin invasion was a priority because the patient had diabetes mellitus. We performed a right STA parietal branch - right MCA anastomosis, followed by a right STA frontal branch - left radial artery graft (RAG) - left MCA bonnet bypass using small intermittent skin incisions.

Results: We drilled a bone groove extending across the entire length of the interposition graft through the small intermittent skin incisions. Furthermore, we applied a right STA-RAG end-to-side anastomosis instead of an endto-end anastomosis to preserve collateral skin anastomosis. Postoperatively, the bypass remained patent, and the patient was discharged without complications.

Conclusion: The bonnet bypass is a potential treatment for CCAO, but the procedure is invasive. Our modified bonnet bypass method enables less invasive management, preventing collapse and malposition of the interposition graft and minimizing skin complications.