Pseudo subclavian steal syndrome: Case report

IntroductionVertebrobasilar insufficiency (VBI) is a condition that results from restricted blood flow to the posterior portions of the brain, which are primarily served by the vertebral and basilar arteries. It is the most common cause of vertigo in the elderly and is usually accompanied by impaired vision and sensation. Congenital abnormalities, atherosclerosis, stroke and/or trauma may all lead to decreased vertebrobasilar circulation. A syndrome called Subclavian Steal Syndrome (SSS), which manifests with similar neurological symptoms but with a different pathophysiology, may also cause VBI.Case presentationA middle-aged female presented with gradual onset fainting and vertigo attacks. Cardiac, auditory and autonomic etiologies were investigated and excluded. Clinical findings and presentation were highly suggestive of subclavian steal. However, subsequent CT angiography showed normal subclavian arteries. Instead, findings included a persistent right trigeminal artery (PTA), stenosis of the right proximal internal carotid artery, atresis of the left vertebral artery and distal segment of right vertebral artery, congenitally compromised changes in vertebral circulation (bilateral absence of the posterior communicating arteries (PCOMs)) and an absent anterograde vertebrobasilar circulation. Symptoms resolved after carotid endarterectomy.DiscussionDue to the absence of a normally developed posterior circulation, the PTA was the main source of blood supply for the patient. Development of recent artheromatous changes in the right internal carotid artery, however, resulted in decreased blood through PTA, further compromising posterior circulation. This resulted in vertebrobasilar insufficiency, and manifested in symptomology similar to SSS.ConclusionsThis clinical encounter illustrates the relative contribution of anatomical and vasoocclusive factors in closely mimicking symptoms of subclavian steal syndrome.     

Steal affecting the central nervous system

Steal is a pathophysiological process in which increased blood flow through a low-resistance vascular bed is sufficient to divert flow away from a region of the central nervous system. Three disease states in which steal may cause neurological deficits due to central nervous system ischemia are reviewed. Subclavian steal occurs when stenosis of the subclavian artery proximal to the vertebral origin causes retrograde flow in the left vertebral artery. Patients with anatomic subclavian steal usually do not develop neurological symptoms but may rarely present with posterior circulation ischemia. Arteriovenous malformations alter cerebral blood flow patterns and regional perfusion pressure. It has been hypothesized that cerebral arteriovenous malformations may cause neurological deficits due to steal and that these deficits may be cured with arteriovenous malformation treatment. Intra-arterial pressure measurements and transcranial velocity studies show regional hemodynamic alterations. However, these changes have not been correlated with presenting symptoms. Evidence from single-photon emission computed tomography does suggest a relationship between regional hypoperfusion and neurological deficits. Coarctation of the aorta may divert flow from the spinal cord circulation through intercostal arteries distal to the stenosis. This is a possible but unproven mechanism of myelopathology. Steal syndromes may be amenable to treatment by open surgical or endovascular approaches. Experimental studies of the pathophysiology of steal are strengthened by precise definitions of the measured parameters and innovative applications of technology.     

Revascularization of the Posterior Circulation

The primary objective of revascularization procedures in the posterior circulation is the prevention of vertebrobasilar ischemic stroke. Specific anatomical and neurophysiologic characteristics such as posterior communicating artery size affect the susceptibility to ischemia. Current indications for revascularization include symptomatic vertebrobasilar ischemia refractory to medical therapy and ischemia caused by parent vessel occlusion as treatment for complex aneurysms. Treatment options include endovascular angioplasty and stenting, surgical endarterectomy, arterial reimplantation, extracranial-to-intracranial anastomosis, and indirect bypasses. Pretreatment studies including cerebral blood flow measurements with assessment of hemodynamic reserve can affect treatment decisions. Careful blood pressure regulation, neurophysiologic monitoring, and neuroprotective measures such as mild brain hypothermia can help minimize the risks of intervention. Microscope, microinstruments and intraoperative Doppler are routinely used. The superficial temporal artery, occipital artery, and external carotid artery can be used to augment blood flow to the superior cerebellar artery, posterior cerebral artery, posterior inferior cerebellar artery, or anterior inferior cerebellar artery. Interposition venous or arterial grafts can be used to increase length. Several published series report improvement or relief of symptoms in 60 to 100% of patients with a reduction of risk of future stroke and low complication rates.     

Single stage multiple stenting in Takayasu's arteritis. Case report

A 32-year-old Filipino female presented with Takayasu's arteritis manifesting as an abrupt onset of syncope. Physical examination revealed diminished consciousness, right hemiparesis, and a large discrepancy in blood pressure between the upper and lower extremities. Magnetic resonance imaging revealed cerebral infarcts in the left basal ganglia and the left temporal lobe. Angiography revealed complete occlusion of the left common carotid artery and severe stenosis of the brachiocephalic artery, the right common carotid artery, and the left subclavian artery. Based on the clinical examination and studies, the diagnosis was Takayasu's arteritis, type I. The patient's condition stabilized after 2 months of prednisone and anti-platelet therapy. Single stage multiple stenting in the brachiocephalic artery, the right common carotid artery, and the left subclavian artery was then performed using high pressure inflation to dilate the arteries due to the remarkably rigid lesions that resulted from extensive and diffuse fibrosis throughout the vessel walls. Although a small intimal flap occurred during inflation of the left subclavian artery, re-dilation was possible with the stent. Even with evidence of notable recovery in blood pressure and cerebral blood flow, no further neurological improvement was observed. In view of the favorable short- and intermediate-term results, single stage multiple stenting may be the optimum treatment option for first-line stent-supported angioplasty in patients with Takayasu's arteritis.     

Protection of anastomotic pathways to the vertebral artery during stenting of external carotid artery stenosis

A 61-year-old man presented with a severe external carotid artery (ECA) stenosis with concomitant ipsilateral internal carotid artery (ICA) occlusion manifesting as amaurosis fugax. The left ophthalmic artery was supplied from the left ECA. The left intracranial ICA was supplied by the collateral flow from the contralateral ICA and ipsilateral ECA through the ophthalmic artery. The left vertebral artery also participated in the latter collateral pathway through the left occipital artery and ascending pharyngeal artery. Percutaneous revascularization of the ECA was performed using a nitinol self-expanding stent. To prevent embolic complications through the ophthalmic or vertebral arteries, distal protection was performed using a balloon. During a 22-month follow-up period, the patient was completely free from any ocular or neurological symptoms. The present case of severe ECA stenosis with ipsilateral ICA occlusion showed that percutaneous balloon angioplasty with stenting is feasible and effective. This intervention requires cautious evaluation of the anastomotic pathways connecting the ECA to the cerebral circulation to avoid embolic complications.     

Carotid artery stenting: current status and future directions

Carotid endarterectomy has been the mainstay of therapy for carotid occlusive disease in stroke prevention. Recent advances in endovascular technology has made carotid angioplasty and stenting a therapeutic modality in the treatment of carotid occlusive disease. The enthusiasm for this minimally invasive carotid intervention is hampered by the possibility of stent-related cerebral embolization, which can result in neurologic complications. Although current available data indicate that the results regarding success and complication rates are similar between carotid stenting and endarterectomy, numerous prospective clinical trials are currently underway to evaluate the efficacy of carotid artery stenting using various forms of cerebral protection devices. This article reviews the current status of carotid stenting, including recent clinical studies and ongoing prospective trials. Strategies relating to cerebral embolization protection are also discussed.     

Improved carotid hemodynamics with vertebral reconstruction

This study tests the hypothesis that vertebral artery reconstruction improves carotid distribution hemodynamics during carotid occlusion. Twelve patients with vertebrobasilar symptoms underwent either direct (9) or indirect (3) vertebral reconstruction. There were six proximal vertebral to common carotid reimplantations, one proximal carotid-vertebral bypass and two distal carotid-vertebral bypasses, all with saphenous vein. Three patients with carotid-subclavian or axillo-axillary bypasses performed for symptomatic vertebral steal were studied at the time of carotid endarterectomy. During temporary ipsilateral carotid occlusion, vertebral reconstruction increased carotid back pressure from 39.3±10.2 mmHg to 46.8±9.5 mmHg (p<0.0001), increased cerebral perfusion pressure from 33.4±10.8 mmHg to 41.0±9.1 mmHg (p<0.0001), decreased the carotid collateral resistance to cerebral vascular resistance ratio from 1.68±0.90 to 1.24±0.64 (p<0.001), and increased the ratio of carotid back pressure to mean systemic arterial pressure from 0.452±0.122 to 0.515±0.118 (p=0.0005). These results are presumed due to increased posterior-to-anterior blood flow in the posterior communicating arteries. Direct or indirect vertebral reconstruction may be a consideration in patients with cerebral ischemic symptomatic and nonreconstructible carotid occlusive disease.     

Current status in cervical carotid artery stent placement

Aim of this paper is to provide background information and the latest developments and studies pertaining to carotid artery stent placement in the treatment of carotid artery occlusive disease. A review of current literature combined with personal experience in the field of carotid stenting is presented. Endovascular stent placement for carotid artery occlusive disease is evolving from its initial controversial position to that of an alternative treatment of extracranial carotid artery disease. The high technical success (98-99%) as well as the relatively few complications makes carotid stenting a substitute for carotid endarterectomy for symptomatic patients and especially those with high medical comorbidities. With the advent of distal embolic protection, the complication rates for carotid stenting have decreased by approximately 50% to 2-4% for most major centers. Hence, with improved technology, carotid stenting is becoming an option for asymptomatic patients, especially those with high surgical risk. Early results for patency and neurological follow-up have also been encouraging. When we first began performing carotid stenting in 1995, we used a mixture of peripheral and coronary techniques. As stent design, guide catheters and cerebral protection devices have become dedicated and sophisticated, the technical success, patency and complication rates have improved. Carotid stenting will increase in application in the future especially among high surgical-risk patients with symptomatic and asymptomatic carotid occlusive disease.     

Changes in blood flow of anterior and middle cerebral arteries following carotid endarterectomy: a transcranial Doppler study

AIM: The aim of the present study was to evaluate the changes in blood flow of anterior and middle cerebral arteries following carotid endarterectomy, using transcranial Doppler (TCD) flow studies. PATIENTS AND METHODS: This study included 100 patients (72 men, mean age 65 years) who underwent carotid endarterectomy because of high-grade carotid stenosis or symptoms of ischemic stroke. Endarterectomy was performed by a distal shunt between the common carotid and internal carotid arteries. Blood flow in the anterior and middle cerebral arteries was assessed by TCD preoperatively and also in the postoperative period (1st and 4th day; 1st, 6th, and 12th month). Collateral circulation in the Willis circle was evaluated by common carotid compression. RESULTS: Patients with bilateral carotid stenosis > or =70% exhibited a significantly increased flow velocity in the ipsilateral anterior cerebral artery (ACA), middle cerebral artery (MCA), and in the contralateral ACA. Patients with entirely occluded contralateral internal carotid artery showed the most pronounced changes in cerebral hemodynamics. Blood flow velocities returned to the preoperative values at 1 to 12 months following endarterectomy. Hyperperfusion syndrome was manifested in 14 patients, who exhibited significantly higher flow velocities in the ipsilateral MCA compared with asymptomatic patients. CONCLUSIONS: A transient bilateral increase of blood flow velocity in the anterior part of the Willis circle may often occur in the immediate postoperative period following carotid endarterectomy. Although its clinical significance is not entirely understood, this increase may be associated with cerebral hyperperfusion syndrome.     

External carotid-basilar anastomosis: case report (author's transl)]

The occipital-vertebral anastomosis is one of the anastomotic channels between the external carotid system and the intracranial vessels. In this paper, we have reported a large, left external carotid-basilar anastomosis which was incidentally revealed in a patient with left hemiparesis due to arteriosclerotic occlusion of the right internal carotid artery. A 55-year-old man suddenly developed left hemiparesis without headache, unconsciousness or vomiting on the morning of January 15, 1973. When he was referred to our service on April 11, the noticeable neurological findings were left hemiparesis and left homonymous hemianopsia. The right carotid angiogram revealed occlusion of the internal carotid artery associated with collateral channels from the external carotid artery. Also a segment of the vertebral artery was visualized via the muscular branch of the occipital artery. In the left carotid angiogram, the posterior circulation was markedly visualized throught the left vertebral artery originating from the external carotid artery trunk. This anastomotic vessel had a large branch with constant caliber leading to the occipital fossa. But the posterior cerebral artery was directly visualized from the internal carotid artery without connection to the basilar artery. Repeated bilateral brachial angiograms revealed hypoplasis of the vertebral arteries. It was suggested that the persistent external carotid-basilar anastomosis might be constantly associated with hypoplasia or aplasia of the bilateral vertebral arteries.     

Carotid-cavernous fistula. Demonstration of asymptomatic vascular "steal"

Abnormal distribution of cerebral vascular flow was studied in a patient who had a traumatic carotid-cavernous sinus fistula. Serial studies were performed using a method for determining relative cerebral vascular flow:99mtechnetium-diethylenetriamine pentaacetic acid (99mTc-DTPA) was injected intravenously and flow data were processed by a digital computer. Serial studies documented the occurrence of a vascular "steal" during temporary carotid occlusion; postoperative studies showed disappearance of the steal and obliteration of thiling arterial structures and capillary filling in the brain, and in demonstrating alteration in the cerebral circulation.     

Neurological deterioration due to cerebral hyperperfusion following carotid endarterectomy. Case report]

Recently attention has been drawn to postoperative cerebral hyperperfusion after carotid endarterectomy (CEA) associated with a preoperative state of impaired cerebral hemodynamics. Rarely postoperative neurological deficits are caused by cerebral edema due to hyperperfusion. The patient was a 65-year-old male with dysarthria and right hemiparesis. Because of the presence of severe stenosis of the left carotid artery, CEA was performed. On the 6th postoperative day, he developed severe right hemiparesis and aphasia due to cerebral edema in the subcortical region of the left cerebral hemisphere. Left carotid angiography showed normal circulation without evidence of the carotid stenosis. Later the cerebral edema and the neurological deficits gradually disappeared.     

Persistierende primitive Hypoglossusarterie (PPHA)

The persistent primitive hypoglossal artery (PPHA) is an embryonal communication between the posterior and anterior circulation of arteries supplying the brain; it is normally obliterated in the early embryonal stages. In a symptom-free patient with arterial occlusive disease, internal carotid artery occlusion was incidentally diagnosed using color duplex ultrasound, whereby the resupply of blood to the distal extracranial internal carotid artery occurred due to retrograde blood flow via the PPHA, resulting in nearly normal blood flow to the distal extra- and intracranial carotid circulation. We describe how color duplex ultrasonography can be used to differentiate therapy-relevant findings, when blood flow is lacking in the proximal internal carotid artery.     

Carotid occlusive disease presenting with loss of consciousness

The authors report 9 patients who presented with loss of consciousness (syncope) due to occlusive carotid artery diseases. All patients were males, and their age ranged from 59 to 83 years. The attack was associated with dehydration or hypotension in 5 patients. MRI demonstrated fresh cerebral infarction in the watershed zone. Cerebral angiography revealed occlusion of the unilateral internal carotid artery (ICA) in 7 patients, severe stenosis of the bilateral ICA in one, and occlusion of the unilateral ICA and severe stenosis of the contralateral ICA in one. Single photon emission tomography (SPECT) or positron emission tomography (PET) suggested reduced cerebral perfusion reserve because of inappropriate development of collateral circulation in 4 out of 9 patients. These 4 patients underwent superficial temporal artery to middle cerebral artery anastomosis and/or carotid endarterectomy. Other 5 patients were medically treated. No further episode of syncope occurred in all 9 patients during follow-up periods. The results suggest that occlusive carotid artery diseases should be taken in considerations as a cause of syncope attack.     

A case of distal posterior cerebral artery aneurysm associated with occlusion of the internal carotid artery

Hemodynamic stress is considered one of the most important factors in the growth of cerebral aneurysms. The authors report a rare case of cerebral aneurysm located at the distal posterior cerebral artery (PCA) in which collateral circulation developed due to occlusion of the internal carotid artery (ICA). A 73-year-old male was admitted to our hospital with a sudden headache and nausea. Computerized tomography (CT) revealed an intracerebral hematoma in the right parieto-occipital lobe and the acute subdural hematoma in both the cerebral interhemispheric fissure and the convexity. Moreover, angiography revealed a saccular aneurysm at the P4 portion of the PCA. The right ICA was occluded at the cervical portion and collateral circulation which had developed in the PCA was extended to the region of the right middle cerebral artery. The aneurysm was clipped 15 days after admission without new neurological complications. This case demonstrates that increased hemodynamic stress plays a role in the growth and rupture of cerebral aneurysm.     

The value and limitations of magnetic resonance angiography of the circle of Willis in patients undergoing carotid endarterectomy

Magnetic resonance angiography is a useful technique to determine the patency of the circle of Willis when compared with conventional four-vessel angiography. The purpose of this study is to determine whether the integrity of the circle of Willis, assessed by magnetic resonance angiography, provides adequate collateral cerebral circulation during carotid endarterectomy and correlates with internal carotid artery back pressure. Over a recent 20-month period, 35 patients were studied preoperatively with magnetic resonance angiography of the carotid bifurcations of the circle of Willis and the vertebrobasilar system. All patients underwent standard carotid endarterectomy with intraoperative measurement of internal carotid artery back pressure. Patients with an internal carotid artery back pressure < 50 mmHg had an intraluminal shunt placed. Deficiencies in branches of the circle of Willis, the carotid bifurcation and the vertebrobasilar system determined by magnetic resonance angiography were correlated with internal carotid artery back pressure using Fisher's exact test. Only one patient had a completely intact circle of Willis. Eleven of 16 patients (69%) who had an internal carotid artery back pressure < 50 mmHg had an occluded A1 segment of the anterior cerebral artery combined with an occluded posterior communicating artery, whereas only five of 19 patients (26%) who had an internal carotid artery back pressure > 50 mmHg had similar findings (P < 0.03). Severity of occlusive disease of the contralateral internal carotid artery and the basilar artery did not independently predict internal carotid artery back pressure. An occluded anterior branch of the circle of Willis in combination with an occluded posterior branch of the circle of Willis is associated with an internal carotid artery back pressure < 50 mmHg. Although magnetic resonance angiography of the circle of Willis may provide valuable anatomic information, it is not sufficiently accurate to predict the need for carotid shunting and therefore its use cannot be justified on a routine basis.     

Subclavian steal syndrome. Part 1: Proximal vertebral to common carotid artery transposition in three patients, and historical review.

Three patients with central nervous system symptoms due to subclavian steal syndrome were treated with proximal vertebral to common carotid artery transposition. Neurological symptoms were relieved or improved in all three, with no decrease in blood pressure or pulse in the ipsilateral upper extremity. The colorful history of this syndrome is reviewed, and the various surgical approaches to its treatment are discussed. Although the literature suggests that the commonly used carotid to subclavian artery bypass graft and other similar extrathoracic procedures are generally safe and effective for relief of symptoms of the steal, there is also evidence that these bypasses may fail to restore antegrade flow in the vertebral artery, and, in fact, may steal from the carotid artery. Thus, the blood flow provided to the brain by these procedure may be hardly more than that provided by vertebral artery ligation, whereas the principal effect is to restore blood flow into the upper extremity. Vertebral artery ligation alone has been used in 20 patients, with neurological improvement in all cases and production of persistent intermittent brachial claudication in only one. These considerations and our patient experience suggest that a relatively simple operation, proximal vertebral to common carotid artery transposition, which emphasizes restoration of flow to the brain rather than to the upper extremity, may be preferable for most patients with neurological symptoms of subclavian steal syndrome.     

Carotid-subclavian bypass and the carotid steal phenomenon

Twelve patients with patent carotid-subclavian bypass grafts were investigated by colour flow duplex imaging to look for a carotid steal. Centre-stream peak systolic flow velocities in the common carotid arteries distal to the take-off of the bypass graft were equivalent to those in the contralateral common carotid artery. On the side of the bypass, common carotid flow proximal to the graft was almost double that on the distal side. Steal phenomena were not identified in the carotid artery either with the arm at rest or during hyperaemia. However, in two instances arm hyperaemia caused reversal of flow in the ipsilateral vertebral artery, suggesting the induction of a subclavian steal. The method of centre-stream peak systolic velocity as an index of flow confirmed that carotid-subclavian bypass can be safely carried out without depriving the cerebral circulation of the normal carotid inflow.     

Octogenarians with contralateral carotid artery occlusion: a cohort at higher risk for carotid endarterectomy?

PURPOSE: Carotid angioplasty and stenting has been proposed as a treatment option for carotid occlusive disease in patients at high risk, including those 80 years of age or older or with contralateral carotid occlusion. We analyzed 30-day mortality and stroke risk rates of carotid endarterectomy (CEA) in patients aged 80 years or older with concurrent carotid occlusive disease. METHODS: From a retrospective review of 1000 patients undergoing 1150 CEA procedures to treat symptomatic and asymptomatic carotid lesions over 13 years, we identified 54 patients (5.4%) aged 80 years or older with concurrent contralateral carotid occlusion. These patients were compared with 38 patients (3.8%) aged 80 years or older with normal or diseased patent contralateral carotid artery and 81 patients (8.1%) younger than 80 years with contralateral carotid occlusion. All CEA procedures involved either standard CEA with patching or eversion CEA, and were performed by the same surgeon, with the patients under deep general anesthesia and cerebral protection involving continuous perioperative electroencephalographic monitoring for selective shunting. Shunting criteria were based exclusively on electroencephalographic abnormalities consistent with cerebral ischemia. RESULTS: The 30-day mortality and stroke rate in patients aged 80 years or older with concurrent contralateral carotid occlusion was zero. CONCLUSIONS: The concept of high-risk CEA needs to be revisited. Patients with two of the criteria considered high risk in the medical literature, that is, age 80 years or older and contralateral carotid occlusion, can undergo CEA with no greater risks or complications. Until prospective randomized trials designed to evaluate the role of carotid angioplasty and stenting have been completed, CEA should remain the standard treatment in such patients.     

What determines the symptoms associated with subclavian artery occlusive disease?

Symptoms associated with subclavian artery stenosis are related to reduced cerebral or arm blood flow. A large difference in blood pressure between the two arms is associated with symptoms of arm ischemia alone and is usually caused by an anatomic variant. The presence or absence of a radiologic steal alone did not seem to determine the type or presence of symptoms. The type of cerebral symptoms seems to be determined by the location of other extracranial vascular stenosis. In patients with hemispheric symptoms there was a higher incidence of anterior circulation insufficiency and a greater reduction in the overall cerebral blood flow. In patients with nonhemispheric symptoms a higher incidence of posterior circulation insufficiency occurred. There may be a small group with nonhemispheric symptoms and a subclavian artery stenosis in whom reversed vertebral artery blood flow is the sole determinant. Perhaps more accurate delineation of other extracranial vascular stenosis would help determine what stenosis in addition to the subclavian artery occlusive disease determines the presenting symptoms. Surgical repair of these lesions may lead to an improved cure rate in this group of patients.