Intracerebral Hemorrhage Following Bypass Surgery for Atherosclerotic Internal Carotid Artery Occlusion Without Hyperperfusion: The Potential Role of Donor-Recipient Mismatch

Abstract

Postoperative intracerebral hemorrhage (ICH) following superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis for atherosclerotic occlusive cerebrovascular disease is rare. Hyperperfusion syndrome is considered a primary cause; however, many aspects remain unclear. A case of a 77-year-old man referred for further examination after presenting with left-sided visual disturbance. Magnetic resonance imaging (MRI) showed no cerebral infarction, but MR angiography (MRA) revealed a left internal carotid artery (ICA) occlusion. Single-photon emission computed tomography (SPECT) using N-isopropyl-p-[¹²³I]iodoamphetamine (¹²³I-IMP) demonstrated that the cerebral blood flow (CBF) value in the left MCA territory was 77% of that on the right side, with a 9.6% increase following acetazolamide challenge. The patient underwent STA-MCA anastomosis to prevent further ischemic stroke. Post-anastomosis, the STA and M4 diameters were 3.1 mm and 1.6 mm, respectively, resulting in a caliber mismatch ratio (STA/M4) of 1.94. Postoperatively, strict systolic blood pressure control (below 130 mmHg) was implemented. However, the patient experienced partial seizures in the left face, while computed tomography (CT) revealed an ICH in the left temporal lobe on the fourth postoperative day. An increase in CBF was not considered to fall within the range of hyperperfusion on ¹²³I-IMP SPECT. His symptoms gradually improved with conservative management, returning to a modified Rankin Scale of 1 by the 10th postoperative day. Even in the absence of imaging evidence of hyperperfusion, a marked donor/recipient caliber mismatch may be a potential risk factor for postoperative hemorrhagic complications following direct bypass surgery for atherosclerotic occlusive disease.

Keywords: atherosclerotic occlusive cerebrovascular disease; hemorrhagic complications; hyperperfusion; sta-mca anastomosis; vessel caliber.

Figure 1. Preoperative magnetic resonance angiography and single-photon emission computed tomography

(A) Preoperative magnetic resonance angiography showing the left internal carotid artery (ICA) occlusion (white arrow). (B) Preoperative single-photon emission computed tomography (SPECT) with N-isopropyl-p-[¹²³I]iodoamphetamine (¹²³I-IMP) was performed to assess cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) to acetazolamide, showing cerebral hypoperfusion (white arrows) and (C) decreased CVR in the left middle cerebral artery (MCA) (white arrows).

Figure 2. Donor-recipient caliber mismatch and hemorrhagic complication

(A) Post-anastomosis, a significant caliber mismatch was observed between the donor STA and the recipient M4. (B) MRI and MRA on day 1 postoperatively revealed no stroke lesions in the brain parenchyma, (C) further demonstrating good bypass patency with strong signals of remarkably thick STA (white arrow). (D) CT on day 4 postoperatively revealed an ICH in the left temporal lobe (white arrow). (E) CBF near the site of anastomosis was not considered to fall within the range of hyperperfusion on ¹²³I-IMP SPECT on postoperative day 5 (white arrow). STA: superficial temporal artery; MRI: magnetic resonance imaging; MRA: magnetic resonance angiography; ICH: intracerebral hemorrhage; CBF: cerebral blood flow; ¹²³I-IMP: N-isopropyl-p-[¹²³I]iodoamphetamine; SPECT: single-photon emission computed tomography