Anesthetic Management of a Patient With Arterial Tortuosity Syndrome Undergoing Cerebral Revascularization Surgery—A Case Report

Arterial tortuosity syndrome is a rare hereditary autosomal recessive connective tissue disorder. The pathognomonic features of this syndrome include lengthening and tortuosity of large- and medium-sized arteries with a predisposition to cardiac and cerebrovascular insufficiencies, aneurysm formation, and dissection.^1–4 The typical craniofacial features may increase the risk of difficult airway, and the associated musculoskeletal abnormalities cause challenges to positioning including a risk for inadvertent cervical spine injury. The diffuse arterial tortuosity and stenosis can increase the risk of pulmonary hypertension, and cardiac and cerebrovascular ischemic events.^2,4,5

We present the case of a 13-year-old child with arterial tortuosity syndrome who underwent occipital encephaloduroarteriomyosynangiosis for posterior circulation insufficiency and discuss the anesthetic management of a patient with arterial tortuosity syndrome, which, until now, has not been reported in the literature. Written informed consent was obtained from the patient’s parent to publish this case report. This article adheres to the CARE (case report) guidelines.

CASE REPORT

A 13-year-old boy, weighing 38 kg with a history of arterial tortuosity syndrome, presented with transient ischemic attacks (TIAs) due to posterior circulation insufficiency. Computed tomography (CT) with angiography of the brain revealed a basisphenoid defect with brain herniation and ectasia (Figure A). Digital subtraction angiography revealed tortuosity of the bilateral internal carotid and vertebral arteries with stenosis of intracranial vessels in both the anterior (Figure B) and posterior circulations (Figure C). In addition, multiple intracranial aneurysms of the posterior circulation were noted. A genetic study revealed a mutation in the SLC2A10 gene, and clinical features were consistent with arterial tortuosity syndrome. The craniofacial features included an elongated face, hypertelorism, downslanting palpebral fissures, epicanthal folds, high arched palate, depressed nasal bridge, retrognathia, and hypoplastic mandible. His airway was Mallampati grade II, with adequate mouth opening and normal neck movements. The previous anesthetic record revealed a Cormack Lehane grade 2 view with video laryngoscopy. The musculoskeletal anomalies included joint laxity and scoliosis, and he had thin, brittle skin. Our patient, in addition to the typical features of arterial tortuosity syndrome, had a basisphenoid defect; that is, defect between the basioccipital and presphenoid bones at the skull base with herniation of cranial contents.

The patient had a history of subarachnoid hemorrhage due to a ruptured basilar apex aneurysm 1 year prior. An attempt to place a flow diverter had failed due to difficulty maneuvering the catheter through his narrowed and tortuous arteries. The perioperative period was complicated by postinduction hypotension and electrocardiographic changes consistent with anterior wall myocardial ischemia. At present, the patient had systemic hypertension, and preoperative echocardiography showed concentric left ventricular hypertrophy with an ejection fraction of 64%, grade I diastolic dysfunction, and no regional wall motion abnormalities. His coronary angiogram revealed tortuous and stenosed coronary vessels with a normal aortic root. His New York Heart Association functional class was 2, and his metabolic equivalent of task (MET) score was >4. He was on losartan for systemic hypertension and dual antiplatelet therapy for his TIA and coronary insufficiency.

The patient had occlusive vessels in both the anterior and posterior circulations. A staged procedure was planned to address the posterior insufficiency first as visual symptoms resulting from posterior cerebral artery insufficiency were more frequent and severe. The neurosurgeon, neuroanesthesiologist, and pediatric neurologist reached a consensus to perform a flow augmentation procedure of the posterior circulation by indirect vascularization with an occipital encephaloduroarteriomyosynangiosis. The dual antiplatelet therapy was stopped 7 days before the surgery, and the patient was bridged with low-molecular-weight heparin until 12 hours before surgery.

Losartan was not administered on the morning of the surgery, and he was premedicated with oral alprazolam 0.25 mg. In the operating room, standard American Society of Anesthesiologists preinduction monitors were placed, and peripheral intravenous access was established. In addition, the left radial artery was cannulated preinduction, and patient state index (PSI) electrodes were placed on the forehead for monitoring the depth of anesthesia. Anesthesia was induced with propofol 2 mg.kg⁻¹ and fentanyl 2 µg.kg⁻¹, targeting a PSI of 25, and paralysis was achieved with vecuronium 0.1 mg.kg⁻¹. The trachea was intubated with a 6.0 cuffed endotracheal tube with the aid of a video laryngoscope. The difficult airway cart and a fiberoptic bronchoscope were readily available in view of the anticipated difficult airway. Ventilation was achieved with volume control mode, targeting an end-tidal carbon dioxide of 35 to 40 mm Hg with an air: oxygen mixture (1:1). Anesthesia was maintained with total intravenous anesthesia with propofol 100 to 250 µg.kg.⁻¹min⁻¹, fentanyl 1 µg.kg.⁻¹min⁻¹, and atracurium 0.5 µg.kg.⁻¹h⁻¹, targeting a PSI of 25 to 30. Right subclavian central venous access was established, and a jugular venous catheter was inserted to measure the jugular venous saturation (SjVO₂). In addition, bilateral near-infrared spectroscopy (NIRS) electrodes were applied to his forehead for monitoring regional cerebral oxygenation (rSO₂). Baseline rSO₂ was noted as 52% on the right side and 53% on the left side with SjVO₂ of 50% and arteriojugular venous oxygen difference (AjVDO₂) of 9. The patient was positioned for the surgery in a left lateral position with his head in a horseshoe head rest. The fraction of inspired oxygen was titrated to achieve a SjVO₂ > 55% with AjVDO₂ < 8 and rSO₂ > 55% in the intraoperative period. rSO₂ remained within 10% of baseline in the intraoperative period. Two early episodes of hypotension >10% from baseline resulted in drastic reduction of rSO2 of >20% and SjVO2 to <50%. Norepinephrine 0.05 µg.kg.⁻¹min⁻¹was initiated, and tight control of blood pressure (BP) within 10% of baseline was achieved until the end of surgery.

The surgery lasted 5 hours, and the patient was extubated at the end of the surgery. The patient was transferred to the neurosurgical intensive care unit for postoperative management. The rSO2 was maintained >55%, the SjVO₂ was >55%, and the AjVDO₂ was <8 in the initial 24 hours. A CT scan on postoperative days 1 and 3 showed no evidence of ischemia, and the patient was discharged home without complications.

The patient returned 6 months later for a encephaloduroarteriomyosynangiosis with a superficial temporal artery for his anterior circulation insufficiency and has been on regular follow-up. He has not had any TIA or stroke since either procedure. He awaits neurosurgical clipping of the basilar apex aneurysm.

DISCUSSIONS

Arterial tortuosity syndrome is a rare connective tissue disease, first described in 1967 by Ertugrul.¹ A mutation of the SLC2A10 gene causes inhibition of extracellular matrix formation, resulting in elongation and tortuosity of arterial vessels leading to aneurysms, dissections, and stenoses.^2,4 The typical manifestations of arterial tortuosity syndrome and anesthetic concerns are summarized in Table 1. Many of these manifestations overlap with other connective tissue disorders, such as Loeys Dietz syndrome, Marfan’s syndrome, and Ehlers-Danlos syndrome, often leading to misdiagnosis. However, extreme tortuosity of the systemic arteries favors the diagnosis of arterial tortuosity syndrome.

Since the patient presented with features of posterior circulation insufficiency and was at risk of recurrent cerebral ischemia and infarction, a flow augmentation procedure was considered. A direct bypass procedure is ideal for vascular insufficiency, but the presence of diffuse tortuous, narrow arteries precluded this procedure. Instead, an encephaloduroarteriomyosynangiosis was performed, wherein an intact occipital artery was placed onto the dural surface to promote indirect revascularization. This procedure unlike the direct bypass procedure does not predispose to cerebral hyperperfusion syndromes, the occurrence of which may have been deleterious to our patient.¹⁰

The anesthetic goals and management of a patient with arterial tortuosity syndrome presenting for a neurovascular surgery are noted in Table 2. In addition, his basisphenoid defect is of particular relevance as placement of a nasogastric tube can cause brain injury. Careful perioperative BP management and maintenance of cerebral oxygenation are essential for these patients with cardiac and cerebral insufficiencies to prevent ischemia. In our patient, preinduction invasive BP monitoring with a titrated induction and maintenance of anesthesia targeting PSI aided in preventing hemodynamic instability.

Neuromonitoring assists in avoiding hemodynamic perturbations that further impair cerebral perfusion. There is a lack of literature on cerebral hemodynamics, including the incidence of cerebral steal in arterial tortuosity syndrome. Anesthetic management of patients with moyamoya disease and other occlusive cerebrovascular diseases was used as a guide for optimal management for our patient.¹¹ NIRS provides real-time information on cerebral oxygenation during neurovascular procedures.¹² Though NIRS assesses only the rSO2 of the frontal area, it was beneficial because our patient had anterior circulation insufficiency. Jugular venous oximetry has the unique capability to detect global ischemia and hyperemia, especially in the setting of stroke and hyperperfusion. Oshima et al¹³ found that global hyperemia as measured by SjVO₂ was concurrent with a drop in regional cerebral blood flow in patients with chronic hypoperfusion states. Similarly, a decrease in rSO₂ with an increase in SjVO₂ indicates ischemia in the context of global hyperemia.

In our patient, the baseline right and left rSO₂ were 52% and 53 %, respectively, which together with an SjVO₂ of 50% and an AjVDO₂ of 9 implied decreased cerebral oxygenation with increased oxygen extraction. The fraction of inspired oxygen and BP were, therefore, augmented to achieve a target SjVO₂ of 55% with AjVDO₂ <8. There was a significant drop in SjVO₂ and rSO₂ when the BP decreased >10% from baseline in our patient. This was prevented thereafter by maintaining BP with norepinephrine. Normocapnia, normoxia, euvolemia, and normotension were maintained, and vasopressors were administered to minimize cerebral hypoxia.

We monitored the SjVO₂ for up to 24-hour postprocedure. An improvement in the SjVO₂ in the postoperative period was noted. This may not have been due to the surgical intervention, as encephaloduroarteriomyosynangiosis is an indirect revascularization procedure that usually takes a few weeks to months to result in collateral formation and an improvement in regional oxygenation. However, in our patient, the improvement in SjVO₂ could be attributed to maintaining the optimal cerebral perfusion as we continued to maintain the intraoperative targets of BP. Moreover, the supplemental oxygen therapy in the postoperative period and the residual metabolic suppression effects offered by the anesthetic medications and adjuvants would have also improved the SjVO₂.

The main concern was maintaining the balance between cerebral oxygenation and demand in this patient. We used NIRS and SjVO₂ as surrogate measures to successfully maintain the optimal cerebral perfusion and oxygenation and avoid ischemic events. Moreover, encephaloduroarteriomyosynangiosis is an indirect minimally invasive neurovascular procedure compared to procedures such as intracranial bypass, wherein the procedure itself can cause neurological injury. Rather, we believe anesthesia is the most crucial factor determining the outcome. Monitors such as somatosensory evoked potentials, and brainstem auditory evoked potentials are neuromonitoring techniques for specific pathways. These monitors will detect ischemia in particular neuronal pathways. Though these could have been additional monitors, we did not use them in our case as the surgical procedure was minimally invasive. We did not use advanced cardiac monitors as the patient had METs >4, and echocardiography showed normal ejection fraction with no regional wall motion abnormalities.

Multimodal monitoring with PSI, rSO₂, and SjVO₂ aided us in optimizing cerebral perfusion and oxygenation, thereby minimizing catastrophic adverse events such as perioperative stroke.

CONCLUSION

Preoperative screening for important clinical features associated with arterial tortuosity syndrome and a tailored anesthetic with appropriate multimodal monitoring and physiological goals allowed the successful management of our patient to prevent ischemic complications.

REFERENCES