Cavernous internal carotid artery aneurysm treated with superficial temporal artery - middle cerebral artery bypass and cervical internal carotid artery ligation using intraoperative middle cerebral artery pressure monitoring - illustrative case

Sep 29, 2026

Symptomatic cavernous portion internal carotid artery (ICA) aneurysms require prompt treatment because of their neurologic impact. This illustrative neurosurgical case describes an 84-year-old woman with bilateral cavernous ICA aneurysms and severe comorbid cervical atherosclerosis and a benign thyroid mass, making endovascular and high-flow bypass strategies challenging. ICA ligation combined with superficial temporal artery–middle cerebral artery (STA-MCA) bypass was performed with intraoperative cortical/systemic and MCA pressure ratio monitoring, with favorable postoperative recovery and complete aneurysm obliteration without new deficits.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages5

Reading Time13 min

AccessFree to download

Background

Observations

Lessons

Illustrative Case

Presentation and imaging

Preoperative evaluations and tests

Surgical approach and intraoperative monitoring

JOURNAL OF NEUROSURGERY: Case Lessons J Neurosurg Case Lessons 11(1): CASE25630, 2026 DOI: 10.3171/CASE25630 Cavernous internal carotid artery aneurysm treated with superficial temporal artery–middle cerebral artery bypass and cervical internal carotid artery ligation using intraoperative middle cerebral artery pressure monitoring: illustrative case Hiroaki Fujita, MD, Fumihiro Matano, MD, PhD, Yohei Nounaka, MD, Asami Kubota, MD, and Yasuo Murai, MD, PhD Department of Neurological Surgery, Nippon Medical School, Bunkyo-ku, Tokyo, Japan BACKGROUND Symptomatic cavernous portion internal carotid artery (ICA) aneurysms require prompt treatment due to their neurological impact. The authors report a case successfully treated with ICA ligation and superficial temporal artery–middle cerebral artery (STA-MCA) bypass, guided by intraoperative cortical/systemic pressure and MCA pressure ratios before and after bypass release to prevent infarction, achieving complete aneurysm obliteration without deficits. OBSERVATIONS An 84-year-old woman presented with sudden-onset headache and right external ophthalmoplegia. Imaging studies revealed a 24-mm aneurysm in the right ICA within the cavernous sinus and a 13-mm aneurysm in the left ICA cavernous segment. Severe common carotid artery atherosclerosis made endovascular treatment challenging. Preoperative cervical CT also revealed a 45-mm × 33-mm benign right thyroid mass, increasing the risk of cervical manipulation. ICA ligation with high-flow bypass was considered high-risk; therefore, ICA ligation with STA-MCA bypass was performed. Intraoperative cortical/systemic pressure and MCA pressure ratios after ligation and two STA-MCA anastomoses were 0.77 and 0 .87, respectively, indicating low ischemic risk. Postoperatively, no new deficits occurred, and ophthalmoplegia improved. LESSONS Intraoperative measurement of cortical/systemic and MCA pressure ratios, combined with thorough preoperative evaluation, can help assess ischemic risk and improve surgical safety. [https://thejns.org/doi/abs/10.3171/CASE25630](https://thejns.org/doi/abs/10.3171/CASE25630) KEYWORDS cavernous sinus; MCA pressure; low-flow bypass Cavernous portion internal carotid artery (ICA) aneurysms are relatively rare among all cerebral aneurysms and are often asymptomatic.1 However, as they enlarge, they may become symptomatic, presenting with headache, facial pain, or oculomotor nerve palsy.2,3 For symptomatic large to giant cavernous portion ICA aneurysms, early therapeutic intervention has been reported to effectively alleviate symptoms.4 Treatment options include both endovascular and surgical approaches.4,5 Surgical options include ICA ligation with or without high-flow bypass (using radial artery [RA] or saphenous vein grafts) or low-flow bypass (e.g. , superficial temporal artery–middle cerebral artery [STA-MCA] bypass) .6,7 However, postoperative cerebral infarction has been reported after ICA ligation with low-flow bypass, even when preoperative tests such as balloon test occlusion (BTO) and single-photon emission CT (SPECT) indicated adequate bypass capacity.8 Measuring the pressure ratio between the cortical surface (MCA) and the systemic circulation (RA)—the MCA/RA ratio—as well as the pressure ratio before and after releasing the bypass graft (MCA pressure [MCAP] ratio) may help assess the risk of postoperative cerebral ischemia.9 To date, there have been no previous reports of these measurements being applied during ICA ligation with low-flow bypass. Here, we report a case of a symptomatic large cavernous ICA aneurysm treated with ICA ligation and low-flow bypass, in which both the MCA/RA ratio and the MCAP ratio were measured intraoperatively in addition to standard preoperative evaluations, resulting in a favorable postoperative outcome. Illustrative Case An 84-year-old woman presented to our hospital with a 3-day history of severe headache, vomiting, double vision, and right-

FAQs

Why are symptomatic cavernous ICA aneurysms treated urgently?

They can rapidly produce neurologic effects, so prompt intervention is emphasized to prevent deterioration.

What preoperative findings influenced the treatment choice in this case?

Severe common carotid artery atherosclerosis limited endovascular options, and a large benign thyroid mass increased risk during cervical manipulation.

How did intraoperative pressure monitoring guide surgical safety?

Cortical/systemic and MCA pressure ratios before and after bypass release were measured to estimate ischemic risk, supporting safe completion of ICA ligation with STA-MCA bypass.

Sep 29, 2026

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