Ondrej Choutka

Use of radial artery grafts in extracranial–intracranial revascularization procedures

Cerebral revascularization procedures have been used in the clinical management of actual or threatened cerebral ischemic states and unclippable cerebral aneurysms. An alternative to a low-flow bypass graft (for example, with the superficial temporal artery) is the use of high-flow grafts created using the saphenous vein (SV) or radial artery (RA). These high-flow grafts are particularly useful when otherwise adequate collateral flow is insufficient to enable sacrifice of the parent vessel without the risk of cerebral ischemia. In their clinical series of 13 patients who underwent high-flow bypass with an RA graft, the authors describe 8 women and 5 men whose ages ranged from 44 to 69 years (mean 57.84 +/- 9.05 years). Indications for RA graft bypass were unclippable aneurysms in 10 patients and occlusive cerebrovascular disease in 3 patients. The authors review the properties of the 2 most common conduits, the SV and RA grafts. They present the technique of high-flow extracranial-intracranial bypass produced using RA grafts in the management of occlusive atherosclerotic disease and complex intracranial aneurysms that are not otherwise amenable to either clip ligation or coil occlusion.

Trends in the Management of Adult Moyamoya Disease in the United States: Results of a Nationwide Survey

BACKGROUND Moyamoya disease is a rare, progressive, steno-occlusive disease of the distal branches of the carotid arteries associated with the development of a profuse basal collateral vascular network. In the United States, the disease occurs sporadically and literature on the topic in limited. With data lacking relative to moyamoya epidemiology and management, we report our survey results among a sample of neurovascular surgeons. METHODS A 16-question survey was sent as a hyperlink by electronic mail to 46 vascular neurosurgery centers and physicians who have published on this topic. Data included patient demographics, referral patterns, treatment, and follow-up. RESULTS Response rate was 70%. Of 32 respondents, 72% evaluated 10 or fewer adults per year, usually referred by a neurologist within their referral pattern. Fifteen (47%) respondents reported that the disease had a bilateral occurrence between 50% and 75% of the time. Most respondents (88%) reported that fewer than 25% of their patients had a previous surgery for the disease. Symptomatology (91%) was the criterion to recommend surgery. Nineteen (59%) respondents regularly assessed cerebrovascular reserve by the addition of acetazolamide challenge to their imaging method of choice, typically single photon emission computed tomography. Treatment was antiplatelets (55%) in asymptomatic adults and superficial temporal artery-to-middle cerebral artery bypass for >75% of symptomatic patients, as assessed by 48% of respondents. Yearly follow-up included cerebral angiography for both superficial temporal artery-to-middle cerebral artery bypass and indirect revascularization. CONCLUSIONS Our survey results quantify epidemiologic trends of moyamoya disease in the United States. Finding a lack of consensus in management strategies, we conclude that collaborative efforts may help to create guidelines for the management of this puzzling entity.

Genetic Determinants of Cerebral Arterial Adaptation to Flow-loading

BACKGROUND In animal models, flow-loading is a necessary and sufficient hemodynamic factor to express the Cerebral Aneurysm (CA) phenotype. Using a rat model, this study characterizes the molecular events that comprise the cerebral arterial response to flow-loading and reveals their significance relating to the CA phenotype. OBJECTIVE To characterize the molecular events that underlie expansive remodeling of cerebral arteries in two genetically distinct inbred rat strains with differential susceptibility to flow-dependent cerebrovascular pathology. METHODS Thirty-two rats underwent bilateral common carotid artery ligation (BCL) (n=16) or Sham Surgery (SS) (n=16). Nineteen days later, vertebrobasilar arteries were harvested, histologically examined and analyzed for mRNA and protein expression. Flow-induced changes in histology, mRNA and protein expression were compared between BCL and SS rats. Differences between aneurysm-prone (Long Evans, LE) and resistant (Brown Norway, BN) strains were evaluated. RESULTS Basilar Artery (BA) medial thickness/luminal diameter ratio was significantly reduced in BCL rats, without significant differences between LE (2.02 fold) and BN (1.94 fold) rats. BCL significantly altered BA expression of mRNA and protein but did not affect blood pressure. Eight genes showed similarly large flow-induced expression changes in LE and BN rats. Twenty-six flow responsive genes showed differences in flow-induced expression between LE and BN rats. The Cthrc1, Gsta3, Tgfb3, Ldha, Myo1d, Ermn, PTHrp, Rgs16 and TRCCP genes showed the strongest flow responsive expression, with the largest difference between LE and BN rats. CONCLUSIONS Our study reveals specific molecular biological responses involved in flow-induced expansive remodeling of cerebral arteries that may influence differential expression of flowdependent cerebrovascular pathology.

The Interlenticulostriate Approach to Very High-Riding Distal Basilar Trunk Aneurysms

BACKGROUND Most high-riding distal basilar trunk aneurysms can be surgically approached via the transsylvian route and its orbitozygomatic variant. However, on rare occasions, the basilar bifurcation may be unusually high and an approach above the carotid terminus may be required. OBJECTIVE In this cadaveric study, we sought to determine the feasibility and exposure limits of the interlenticulostriate approach (ILSA). METHODS A standard transsylvian approach was performed in 10 cerebral hemispheres of 5 formalin-fixed, silicone-injected cadaver heads. The interpeduncular cistern was exposed via the opticocarotid window, carotid-oculomotor window, and supracarotid ILSA window. The latter was measured and an aneurysm clip or ventriculostomy stylet was placed as high as possible through each corridor. Using noncontrast 3-D rotational angiography, clip/stylet positions were measured relative to the dorsum sellae. RESULTS ILSA provided a 9.4 × 4.6 mm mean surgical corridor, just enough room for a standard clip applier. This space was limited by the carotid bifurcation inferiorly, the lenticulostriate arteries medially and laterally, and the optic tract superiorly. There was no difference between opticocarotid and carotid-oculomotor windows, in terms of clip position (+8.9 vs +8.6 mm, respectively; P = .78). In contrast, ILSA provided significantly improved superior exposure, compared with either approaches (mean stylet position: +14.3 mm; P = .005). The exposure benefit afforded by ILSA was consistent across all 10 hemispheres, ranging from +2.5 to +8 mm. CONCLUSION For high-riding distal basilar trunk aneurysms that cannot be reached via the frontotemporal orbitozygomatic approach, ILSA can provide a viable route of access. Vascular neurosurgeons should be familiarized with this approach.

Changes in computed tomography perfusion parameters after superficial temporal artery to middle cerebral artery bypass: an analysis of 29 cases.

Introduction Analysis of computed tomography perfusion (CTP) studies before and after superficial temporal artery to middle cerebral artery (STA-MCA) bypass is warranted to better understand cerebral steno-occlusive pathology. Methods Retrospective review was performed of STA-MCA bypass patients with steno-occlusive disease with CTP before and after surgery. CTP parameters were evaluated for change after STA-MCA bypass. Results A total of 29 hemispheres were bypassed in 23 patients. After STA-MCA bypass, mean transit time (MTT) and time to peak (TTP) improved. When analyzed as a ratio to the contralateral hemisphere, MTT, TTP, and cerebral blood flow (CBF) improved. There was no effect of gender, double vessel versus single vessel bypass, or time until postoperative CTP study to changes in CTP parameters after bypass. Conclusions Blood flow augmentation after STA-MCA bypass may best be assessed by CTP using baseline MTT or TTP and ratios of MTT, TTP, or CBF to the contralateral hemisphere. The failure of cerebrovascular reserve to improve after cerebral bypass may indicate irreversible loss of autoregulation with chronic cerebral vasodilation or the inability of CTP to detect these improvements.