Angiographically occult intracranial aneurysms found during microsurgical aneurysm clipping of known aneurysms

J Neurosurg 132:434–441, 2020

During the microsurgical clipping of known aneurysms, angiographically occult (AO) aneurysms are sometimes found and treated simultaneously to prevent their growth and protect the patient from future rupture or reoperation. The authors analyzed the incidence, treatment, and outcomes associated with AO aneurysms to determine whether limited surgical exploration around the known aneurysm was safe and justified given the known limitations of diagnostic angiography.

METHODS An AO aneurysm was defined as a saccular aneurysm detected using the operative microscope during dissection of a known aneurysm, and not detected on preoperative catheter angiography. A prospective database was retrospectively reviewed to identify patients with AO aneurysms treated microsurgically over a 20-year period.

RESULTS One hundred fifteen AO aneurysms (4.0%) were identified during 2867 distinct craniotomies for aneurysm clipping. The most common locations for AO aneurysms were the middle cerebral artery (60 aneurysms, 54.1%) and the anterior cerebral artery (20 aneurysms, 18.0%). Fifty-six AO aneurysms (50.5%) were located on the same artery as the known saccular aneurysm. Most AO aneurysms (95.5%) were clipped and there was no attributed morbidity. The most common causes of failed angiographic detection were superimposition of a large aneurysm (type 1, 30.6%), a small aneurysm (type 2, 18.9%), or an adjacent normal artery (type 3, 36.9%). Multivariate analysis identified multiple known aneurysms (odds ratio [OR] 3.45, 95% confidence interval [CI] 2.16–5.49, p < 0.0001) and young age (OR 0.981, 95% CI 0.965–0.997, p = 0.0226) as independent predictors of AO aneurysms.

CONCLUSIONS Meticulous inspection of common aneurysm sites within the surgical field will identify AO aneurysms during microsurgical dissection of another known aneurysm. Simultaneous identification and treatment of these additional undiagnosed aneurysms can spare patients later rupture or reoperation, particularly in those with multiple known aneurysms and a history of subarachnoid hemorrhage. Limited microsurgical exploration around a known aneurysm can be performed safely without additional morbidity.

Comparison of indocyanine green fluorescent angiography to digital subtraction angiography in brain arteriovenous malformation surgery

ICG and AVM

Acta Neurochir (2015) 157:351–359

The potential utility of intraoperative microscope-integrated indocyanine green (ICG) fluorescence angiography in the surgery of brain arteriovenous malformations (AVMs) and evaluation of the completeness of resection is debatable. Postoperative catheter angiography is considered the gold standard. We evaluated the value of ICG and intraoperative catheter angiography in this setting.

Methods Between January 2009 and July 2013, 37 patients with brain AVMs underwent surgical resection of their vascular lesions. ICG videoangiography and an intraoperative catheter angiography were performed in 32 cases, and a routine postoperative angiogram was performed within 48 h to 2 weeks after surgery. The usefulness of ICG findings and the ability to confirm total resection and to identify residual nidus or persistent shunt were assessed and compared to intraoperative and postoperative digital subtraction angiography, respectively.

Results There were 7 grade 1, 11 grade 2, 11 grade 3 and 3 grade 4 Spetzler-Martin classification AVMs. ICG angiography helped to distinguish AVM vessels in 26 patients. In 31 patients, it demonstrated that there was no residual shunting. In one patient, a residual AVMwas identified and further resected. Intraoperative catheter angiography detected two additional small residuals that were missed by ICG angiography, both deep in the surgical cavity. Further resection of the AVM was performed, and total resection was confirmed by a repeat intraoperative angiogram. Postoperative angiography in a patient with a grade 4 lesion revealed one additional small deep residual AVM nidus with persistent late shunting missed on both ICG and intraoperative angiography. Overall ICG angiography missed three out of four residual AVMs after initial resection, while the intraoperative angiogram missed one.

Conclusion Although ICG angiography is a helpful adjunct in the surgery of some brain AVMs, it’s yield in detecting residual AVM nidus or shunt is low, especially for deepseated lesions and higher grade AVMs. ICG angiography should not be used as a sole and/or reliable technique. Highresolution postoperative angiography must be performed in brain AVM surgery and remains the best test to confidently confirm complete AVM resection.

Yield of CTA in catheter angiography–negative SAH

J Neurosurg 117:309–315, 2012

The yield of CT angiography (CTA) and MR angiography (MRA) in patients with subarachnoid hemorrhage (SAH) who have a negative initial catheter angiogram is currently not well understood. This study aims to determine the yield of CTA and MRA in a prospective cohort of patients with SAH and a negative initial catheter angiogram.

Methods. From January 1, 2005, until September 1, 2010, the authors instituted a prospective protocol in which patients with SAH—as documented by noncontrast CT or CSF xanthochromia and a negative initial catheter angiogram— were evaluated using CTA and MRA to assess for causative cerebral aneurysms. Two neuroradiologists independently evaluated the noncontrast CT scans to determine the SAH pattern (perimesencephalic or not) and the CT and MR angiograms to assess for causative cerebral aneurysms.

Results. Seventy-seven patients were included, with a mean age of 52.8 years (median 54 years, range 19–88 years). Fifty patients were female (64.9%) and 27 male (35.1%). Forty-three patients had nonperimesencephalic SAH (55.8%), 29 patients had perimesencephalic SAH (37.7%), and 5 patients had CSF xanthochromia (6.5%). Computed tomography angiography demonstrated a causative cerebral aneurysm in 4 patients (5.2% yield), all of whom had nonperimesencephalic SAH (9.3% yield). Mean aneurysm size was 2.6 mm (range 2.1–3.3 mm). Magnetic resonance angiography demonstrated only 1 of these aneurysms. No causative cerebral aneurysms were found in patients with perimesencephalic SAH or CSF xanthochromia.

Conclusions. Computed tomography angiography is a valuable adjunct in the evaluation of patients with nonperimesencephalic SAH who have a negative initial catheter angiogram, demonstrating a causative cerebral aneurysm in 9.3% of patients.