Cranial Vascular Neurosurgery II Flashcards
A 75-year-old man with a history of recent memory impairment is admitted with headache, confusion, and a left homonymous hemianopsia. There is no history of hypertension or malignancy. Non-contrast CT scan and GRE MRI are shown. Which one of the following is the most likely cause of this patient’s symptoms and signs?
a. Multi-infarct dementia
b. Mycotic aneurysm
c. Amyloid angiopathy
d. Undiagnosed hypertension
e. Gliomatosis cerebri
c. Amyloid angiopathy
Cerebral amyloid angiopathy (CAA) as a cause of ICH has been implicated in as many as 15% patients older than 60 years of age and almost 20% of patients 70 years of age and older. Depo- sition of β-amyloid protein in the vessel walls of small and medium sized arteries within the aging brain predisposes to both ICH and dementia. The locations of the bleeds are lobar or cortical-subcortical as opposed to the basal gang- lia location in hypertensive IPH. Most com- monly, bleeds are seen in the frontal lobe, followed by the parietal, occipital, and temporal lobes. Hemorrhage into the deep gray matter or cerebellum is uncommon and there may be evidence of prior macrohemorrhages or microhe- morrhages. Patients with CAA are at substantial increased risk for recurrent hemorrhage, estimated at approximately 10% annually. On CT it is common to see multiple microhemor- rhages and hematomas of varying ages. Magnetic resonance imaging including GRE and/or susceptibility-weighted imaging (SWI) is recom- mended as a further step in evaluation of patients suspected of CAA. MRI including MRA/MRV is reasonably sensitive at identifying secondary causes of hemorrhage. A catheter angiogram may be considered if clinical suspicion is high or noninvasive studies are suggestive of an under- lying vascular cause. On GRE sequences micro- bleeds are round, punctate, hypointense foci less than 5-10 mm in size in brain parenchyma seen in 80% of patients with primary ICH (hyperten- sion and amyloid angiopathy), 25% of patients with ischemic stroke, and 8% of elderly people. They correspond to hemosiderin-laden macro- phages lying adjacent to the vessels and indicate prior extravasation of blood. Microbleeds have been suggested to be predictors of bleeding-prone angiopathy. Some studies have shown that patients with microbleeds may be at increased risk for ICH after anticoagulation or thrombolytic treatment; however, this is controversial and not confirmed in all studies. The STICH trial randomized patients with spontaneous supratentorial ICH (<72 h; unlikely due to vascular malformation/ aneurysm/tumor), hematoma >2 cm, and GCS 5 or more where there was clinical equipoise about hematoma evacuation to either early surgery or initial conservative management with possibility of ICH evacuation if deemed appropriate by the treating physicians. They found that except for possibly those with superficial ICHs, craniotomy at 1 day or longer after onset is not better than initial conservative medical treatment with or without later craniotomy for patients who have deterioration. STICH II trial focused on those with spontaneous, superficial lobar ICH (<1 cm from cortical surface; volume 10-100 ml) without intraventricular hemorrhage in conscious patients and found that early surgery (<12 h after random- ization) does not increase the rate of death or dis- ability at 6 months compared to initial conservative management (with delayed surgery if judged nec- essary). Patients in the STICH II trial with a poor prognosis (GCS 9-12) did better with early surgery, whereas those with a good prognosis did not (as the ability to observe and operate on only those who deteriorate is more beneficial over- all for this group).
A 71-year-old presents with sudden headache and confusion. CT is shown. Which one of the following is most likely cause?
a. Vasculitis
b. Mycotic aneurysm
c. Amyloid angiopathy
d. Undiagnosed hypertension
e. Gliomatosis cerebri
d. Undiagnosed hypertension
Hypertensive ICH accounts for over 50% of cases. Hemorrhage occurs most commonly in the basal ganglia /thalamus (80%), pons (5-10%) and the cerebellar hemispheres (5-10%). Over 90% of the patients are older than 45 years of age. The bleeding results from the rupture of small penetrating arteries. In 1868 Charcot and Bouchard described the cause of the bleeding as rupture of Charcot-Bouchard microaneurysms in the walls of small penetrating arterioles (micro- aneurysms). Intraparenchymal hemorrhage may result from a large and heterogeneous group of causes, including primary causes such as hyperten- sion and amyloid angiopathy or secondary causes such as AVM, intracranial aneurysms, cavernous angiomas, dural venous sinus thrombosis, intracranial neoplasms, coagulopathy, vasculitis, drug use, and hemorrhagic ischemic stroke. Underlying vascular abnormalities must always be considered and excluded if suspected due to the high risk for recurrent hemorrhage and the availability of treatment options. Clinical symp- toms suggesting a secondary cause include pro- drome of headache or neurologic deficits before the onset of the accident or other clinical findings that suggest an underlying disease. Imaging find- ings suggestive of secondary causes include the presence of SAH and ICH at the same time, unusual shape of the hematoma, increased edema compared to the size of the hematoma, and visual- ization of a masslike lesion or abnormal vessels. Hematoma expansion occurs in approximately one third of acute primary IPH cases and is associated with high mortality, disability, and functional deterioration. The CT shown demonstrates basal ganglia hemorrhage with intraventricular extension and surgical manage- ment will be directed towards developing hydro- cephalus via external ventricular drainage.
Which one of the following statements regarding the World Federation of Neuro- logical Surgeons (WFNS) subarachnoid grading scale is most accurate?
a. It was derived from statistical analysis of a large cohort of consecutive SAH patients from a single center
b. It was derived from statistical analysis of a large cohort of consecutive SAH patients from multiple centers
c. It was created based on expert opinion using the results of the International Cooperative Aneurysm Studi
d. It is inferior to the Hunt & Hess grading scale in terms of predicting outcome at 3 months
e. It is superior to the modified Fisher score in predicting risk of vasospasm
c. It was created based on expert opinion using the results of the International Cooperative Aneurysm Study
Which one of the following statements regarding the Hunt & Hess subarachnoid hemorrhage grading scale is most accurate?
a. Based on a prospective study of 275 patients with aneurysmal subarachnoid hemorrhage treated in a single center
b. Assesses risk of vasospasm on initial diagnostic cerebral angiography
c. Intended to guide timing of aneurysm clipping based on grades of surgical risk
d. Meningeal reaction alone does not increase surgical hazard
e. Suggests that in the absence of ICH, grade III patients should be operated on early
c. Intended to guide timing of aneurysm clipping based on grades of surgical risk
The Hunt and Hess scale (1968) aimed to retro- spectively create an index of surgical risk and to aid neurosurgeons in deciding on the appropriate time after SAH at which the neurosurgeon should operate. Surgical risk was felt to be best estimated by the intensity of meningeal inflammatory reac- tion, the severity of neurological deficit/level of arousal (indicating arterial spasm, ischemia, and brain edema and thus greater vulnerability to manipulation), and the presence of associated disease. Their practice at that time was to take grade I and II to surgery as soon as a diagnosis could be made (ideally <24 h admission), while graded III-V treated conservatively until they improved to Grade I or II (except in the case of multiple rebleeds or life-threatening ICH). After retrospective review of 275 cases, they concluded that aneurysm clipping can be accomplished with an extremely low mortality rate in the absence of severe meningeal reaction, neurological deficit,
or serious associated disease (preop Grade I 1.4% versus Grade II 22% versus Grade III-IV approx. 40%) and that meningeal reaction alone (Grade II) increases surgical hazard. Thus they suggested prompt surgical intervention is impor- tant for patients admitted in good condition, while for the more seriously ill conservative ther- apy should be utilized until their condition improves. In 1974, Hunt and Kosnik proposed a modification of their SAH scale by adding a zero grade for unruptured aneurysms and 1a grade for a fixed neurological deficit in the absence of other signs of SAH. Although the Hunt and Hess scale is easy to administer, the classifications are arbi- trary, some of the terms are vague (e.g. drowsy, stupor, and deep coma) and some patients may pre- sent with initial features that defy placement within a single grade. In one study which compared Hunt and Hess Scale with GCS, and WFNS Scale in a series of 185 patients with aneurysmal SAH showed that it had the strongest predictive power for GOS at 6 months, though half of poor-grade patients achieved good recoveries suggesting that current admission grading scales are not accurate enough to be the sole basis for treatment decisions. They also found that scores on the day of operation were of more prognostic value than values observed immediately after hospitalization. Furthermore other studies have struggled to find outcome differences between the individual grades, but did when lower grades were merged suggesting the possibility of an oversplitting error weakening the prognostic power of the scale.
Which one of the following statements regarding the Fisher and Modified Fisher scales is LEAST accurate?
a. Fisher Scale (1980) was proposed to predict cerebral vasospasm after aneurysmal SAH and retrospectively validated in 47 patients
b. Fisher scale (1980) utilized blood clot thickness measurements still calculable from modern CT scans
c. Fisher scale (1980) grade 4 SAH is characterized by localised clot and/or vertical layer within the subarachnoid space >1 mm thick
d. After adjusting for early angiographic vasospasm, history of hypertension, neurological grade, and elevated admission mean arterial pressure, the Fisher scale (1980) remains a significant predictor of vasospasm
e. Odds ratio of symptomatic vasospasm in Modified Fisher grade 4 SAH is two-fold higher than those with Grade 0-1 SAH
e. Odds ratio of symptomatic vasospasm in Modified Fisher grade 4 SAH is two-fold higher than those with Grade 0-1 SAH
The Fisher Scale (1980) was proposed to predict cerebral vasospasm after aneurysmal SAH and prospectively validated in 47 patients: slight to severe vasospasm was seen in 4/11 (36%) grade 1, 3/7 (43%) grade 2, 24/24 (100%) of grade 3, and 2/3 (67%) of grade 4 patients. Limitations of this original scale include: (i) poor resolution compared to current CT scans, (ii) blood thick- ness measurements used were actual measure- ments on printed CT scan images and had no relationship to the real clot thickness, (iii) No SAH and SAH <1 mm in true thickness (Grades 1 and 2) are both uncommon, and (iv) it does not account for patients with thick SAH with ICH/ IVH or those with ICH/IVH alone. More recent evidence that the Fisher scale may not correlate with risk of vasospasm resulted in the Fisher scale being compared to the Modified Fisher scale (2006) in 1355 patients with SAH (in placebo arm of RCT for tirilazad), of whom 33% developed vasospasm. Early angiographic vasospasm, history of hypertension, neurological grade, and elevated admission mean arterial pressure were identified as risk factors for symptomatic vasospasm. After adjusting for these variables, the modified Fisher scale remained a significant predictor of symptomatic vasospasm (adjusted OR 1.28, p1⁄40.01) while the original Fisher scale was not (adjusted OR 1.1, p 1⁄4 0.488).
Which one of the following statements regarding moyamoya disease is LEAST accurate?
a. Incidence is higher in Japan compared to Western countries
b. More prevalent in females
c. Adults usually present with progressive
cerebral ischemia
d. Progression of disease is more commonly
seen in children
e. Ischemic symptoms can be triggered by
crying in children with moyamoya disease
c. Adults usually present with progressive cerebral ischemia
Moyamoya disease is characterized by bilateral stenosis or occlusion of the terminal portion of the ICAs and/or the proximal portions of the ACAs and MCAs. Moyamoya disease is also char- acterized by irregular perforating vascular net- works, called moyamoya vessels, near the occluded or stenotic regions corresponding to the lenticulostriate and thalamoperforate arteries. The associated tuft of collateral vessels that forms at the base of the skull gives the angiographic appearance of a hazy “puff of smoke,” or “moya- moya” in Japanese. Incidence rate in Japan is 0.5-1 per 100,000 people, with a prevalence of 10.5 patients per 100,000. Improved diagnostic measures and prognosis for these patients may have contributed to the increase in the incidence and prevalence of the disease. MMD cases in the US show a lack of bimodal age of onset, preva- lence of the ischemic type at all ages, more benign symptoms at presentation, and better re- sponse to surgical treatment. The incidence of MMD in California was only 0.087 per 100,000 from 1987 to 1998, even with a higher Asian population. It is more prevalent among women. Genome-wide association study identified the RNF213 gene in the 17q25 region as a suscepti- bility gene for moyamoya disease among East Asians. Secondary causes of “moyamoya syn- drome” include infection, autoimmunity, other inflammatory conditions, and cranial irradiation. Presentation may be: ischemic 63.4%, hemor- rhagic 21.6%, epileptic 7.6%, and “other” 7.5%. The ischemic type of MMD predominates in childhood, making up 69% of cases in patients under 10 years old and Ischemic symptoms are often instigated by hyperventilation (e.g. crying). The symptoms may present repetitively and can result in motor aphasia, cortical blindness, mental retardation, and low IQ over the long term. The hemorrhagic type of MMD occurs in 66% of adult cases exhibit hemorrhages with a higher occurrence in females. Progression of occlusion is more common in children than adults. Due to a poor response to medical therapy, direct and indirect cerebral bypass techniques have been devised with the goals of promoting neoangio- genesis, inducing collateral vessel formation, and restoring perfusion to oxygen-deprived areas of the brain. The direct techniques can immedi- ately augment the blood supply as well as pro- mote neoangiogenesis. surgical intervention improves the outcomes of patients with symp- tomatic MMD. Direct revascularization is the treatment of choice and may lead to immediate improvement of symptoms, but is technically challenging and is associated with risks such as hemorrhage and cerebral hyperperfusion syn- drome. The pediatric population is typically treated with indirect revascularization because (i) the likelihood of angiogenesis is higher in children than in adults and (ii) direct bypass is technically challenging and more prone to thrombosis in children. Disadvantages of indirect revascularization relate to longer time for collat- eral formation and angiogenesis and that it may preclude the option of subsequent direct bypass in symptomatic children if the STA is used or compromised.
Which one of the following statements regarding moyamoya in pregnancy/lifestyle is LEAST accurate?
a. Contraception increases risk of bypass graft thrombosis
b. Blood donation may increase the risk of TIA/stroke in moyamoya patients
c. Cesarean section is advisable in those with Suzuki stage 3 moyamoya
d. Aspirin should be continued throughout pregnancy
e. Good cerebral circulation on SPECT or absence of frequent symptoms due to moyamoya disease within 1 year before pregnancy may reduce complications associated with vaginal delivery
c. Cesarean section is advisable in those with Suzuki stage 3 moyamoya
General lifestyle advice for pre- or post-bypass moyamoya patients includes: (i) avoid oral contra- ceptives or hormone replacement therapy due to the risk of cerebral thrombosis (especially through bypass graft), (ii) lifelong aspirin, (iii) ensure headgear/helmets do not constrict blood supply to the bypass, (iv) avoid donating blood due to risk of TIA/stroke from loss of intravascu- lar volume, (v) normal pregnancy and vaginal delivery is possible under specialist joint care. Cerebral infarction and intracranial hemorrhage are the major concerns in pregnancies with moya- moya disease because these conditions greatly influence the prognoses of the mother and new- born infant. Intrapartum, cerebral blood flow decreases due to hyperventilation and increases due to elevation of blood pressure caused by pain and uterine contractions. These increases and decreases of cerebral blood flow cause cerebral ischemia and hemorrhage. However, vaginal delivery is possible if cerebral blood flow can be controlled, and this may be achieved by control- ling blood flow to the brain with epidural anesthesia. When vaginal delivery is selected, there is evidence to suggest that good cerebral circulation on SPECT or absence of frequent symptoms due to moyamoya disease within 1 year before pregnancy is important for avoiding complications.
Which one of the following statements regarding diagnosis of moyamoya disease is most accurate?
a. Unilateral moyamoya disease can be diagnosed with MRI and MRA
b. Suzuki stage 1 shows first evidence of developing moyamoya vessels at the base of the brain
c. Diagnosis does not requires exclusion of causes of secondary “moyamoya syndrome”
d. Bilateral stenosis at the terminal portion of the ICA and abnormal vascular networks in the vicinity of the stenotic lesion in the arterial phase on angiography and no secondary cause for this appearance would be sufficient to diagnose moyamoya disease
e. Suzuki stage 6 is characterized solely by the complete absence of moyamoya vessels
d. Bilateral stenosis at the terminal portion of the ICA and abnormal vascular networks in the vicinity of the stenotic lesion in the arterial phase on angiography and no secondary cause for this appearance would be sufficient to diagnose moyamoya disease
Clinical diagnosis of moyamoya disease is based on (A) cerebral angiography (gold standard) and/or (B) MRI/MRA, and (C) exclusion of sec- ondary moyamoya syndrome (arteriosclerosis, autoimmune, meningitis, brain tumor, Down’s syndrome, NF-1, head trauma, cranial irradia- tion, sickle cell disease, and others). Historically, only bilateral cases could be diagnosed defini- tively while unilateral cases with appropriate criteria could be termed probable moyamoya dis- ease. However, the most recent Japanese diagnostic criteria state that definitive diagnosis of moyamoya disease requires catheter angiogra- phy in unilateral cases while bilateral cases could be promptly diagnosed by either catheter angiog- raphy or magnetic resonance (MR) imaging/ angiography. Cerebral angiography should show (i) stenosis or occlusion at the terminal portion of the ICA and/or at the proximal portion of the ACAs and/or the MCAs and (ii) abnormal vascu- lar networks in the vicinity of the occlusive or ste- notic lesions in the arterial phase. Cerebral angiography is not mandatory when MR imaging and MR angiography clearly demonstrate: (i) bilateral stenosis or occlusion at the terminal por- tion of the ICA and at the proximal portion of the ACAs and MCAs on MR angiography, and (ii) bilateral abnormal vascular network in the basal ganglia on MR angiography (>2 apparent flow voids are observed in 1 side of the basal ganglia on MR imaging). Cerebral angiography serves for diagnosis, surgical planning, and monitoring progression via Suzuki staging. The utility of Suzuki staging may be mostly in children (as many adults remain within the same stage), and even then most cases belong to stages 3-5, and stages are not strongly related to clinical symptoms.
Which one of the following is the most appropriate indications of cerebral revascularization surgery in moyamoya disease?
a. Suzuki stage 3 moyamoya disease on cerebral angiography
b. Intracranial hemorrhage
c. Recurrent ischemic episodes in a child
triggered by crying
d. Asymptomatic moyamoya
e. Planned pregnancy
c. Recurrent ischemic episodes in a child triggered by crying
Direct revascularization surgery such as STA-MCA anastomosis, as well as indirect revas- cularization, is established as an effective proce- dure for the moyamoya disease patients with ischemic symptoms. However, the recently pub- lished results of the Japanese Adult Moyamoya trial have provided us with level I evidence for the potential benefit of direct cerebral revascular- ization for preventing recurrent bleeds in adults with hemorrhagic moyamoya disease. In sum- mary, 80 adult patients with a recent history (<12 months) of cerebral hemorrhage were randomly assigned to either direct extracranial- to-intracranial (EC-IC) bypass or medical management and followed for 5 years. Significant morbidity was seen in 34% of the patients man- aged conservatively compared with 14.3% of the patients in the surgical group. Similarly, patients in the nonsurgical arm were approximately 3 times more likely to experience a recurrent bleed than patients who underwent surgery (31.6% vs. 11.9%) suggesting a preventive effect of direct bypass against rebleeding. JAM trial strongly encourages direct revascularization surgery for reducing the risk for rebleeding in adult moya- moya disease patients presenting with intracranial hemorrhage, although the statistical significance was marginal. Finally, revascularization surgery for asymptomatic moyamoya disease patients is not recommended due to the uncertainty of the natural history of this patient population.
Which one of the following statements regarding complications of cerebral bypass surgery for moyamoya disease is LEAST accurate?
a. Cerebral hyperperfusion syndrome gen- erally occurs 2-6 days after STA-MCA bypass
b. Cerebral hyperperfusion can result in hemorrhagic conversion of moyamoya disease
c. Watershed shift phenomenon is commoner in adults than children
d. Watershed shift phenomenon describes retrograde blood supply from STA- MCA bypass may interfere with the anterograde blood flow from the proximal MCA
e. Mechanical compression by swollen temporal muscle flap can result in cerebral edema
c. Watershed shift phenomenon is commoner in adults than children
Surgical complications of moyamoya disease include both neurological and non-neurological complications, and neurological complications include perioperative cerebral infarction and cerebral hyperperfusion syndrome. Mechanisms for ischemia include “watershed shift phenome- non” where retrograde blood supply from STA- MCA bypass may interfere with the anterograde blood flow from the proximal MCA, and thus result in the temporary decrease in CBF at the cortex supplied by the adjacent branch of MCA—particularly in pediatric moyamoya dis- ease. Secondly, thrombo-embolic complications related to the anastomosed site and the mechan- ical compression by swollen temporal muscle flap could also cause cerebral ischemia in the acute stage. STA-MCA bypass may temporarily lead to heterogeneous hemodynamic condition even within the hemisphere operated on. Cerebral hyperperfusion syndrome is one of the most seri- ous complications and may occur in nearly 40% of adult patients with moyamoya disease 2-6 days after STA-MCA bypass. Rapid focal increase in CBF (hyperemia) at the site of the anastomosis could result in vasogenic edema and/or hemor- rhagic conversion in moyamoya disease. Focal cerebral hyperperfusion can cause temporary focal neurological deficit such as aphasia, hemi- paresis, and dysarthria in a blood pressure depen- dent manner. In general, good perioperative hydration, hemoglobin control, and routine use of anti-platelet agent are essential to avoid ische- mic complications.
A 73-year-old patient has sudden onset left facial droop left hemiparesis 3/5 and slurred speech, left facial droop developing 90 min ago. CT head scan does not show any large infarct of hemorrhage. ASPECT score is 10. CT angiography is performed and shown below. CT perfusion shows elevated mean transit time, reduced cerebral blood flow, and preserved cerebral blood volume in the right MCA territory. There is no past medi- cal history and he has not had any recent surgery. BP is 179/95, HR 102. Which one of the following evidence-based strategies is appropriate?
a. Intravenous thrombolysis, if unsuccessful in 30 min thrombectomy
b. Mechanical proceed to mechanical
thrombectomy without thrombolysis
c. Intravenous thrombolysis followed by
heparin infusion
d. Aspirin 300 mg
e. Warfarinization
a. Intravenous thrombolysis, if unsuccessful in 30 min thrombectomy
In 1995 with the validation of intravenous recom- binant tissue plasminogen activator (IV rtPA) in studies demonstrating improved clinical out- comes in patients treated within 3 h of stroke ictus dramatically improved stroke therapy. Despite the clinical benefits of IV rtPA, disap- pointments remained concerning modest recana- lization rates, ranging between 4.4% for distal internal carotid artery occlusion, 4% for basilar artery occlusions and 30% for middle cerebral artery (MCA) M1 and M2 segment occlusions. Initial trials of endovascular therapy versus IV rtPA alone (e.g. MERCI, IMS III, SYNTHESIS Expansion, MR RESCUE trials) failed to defini- tively demonstrate superiority of mechanical embolectomy—possibly due to use of first gener- ation stent retrievers with poor recanalization rates, and limited availability of advanced imaging to confirm vessel occlusion and identify prenum- bral pattern/infarct core. Recently, however, 5 published randomized controlled studies (ESCAPE, MR CLEAN, SWIFT Prime, EXTEND IA, REVASCAT) using new genera- tion devices with recanalization rates 58-88% and advanced CT/MR imaging for patient selec- tion (assessing collateral circulation, mismatch ratio and ischemic core volume) have provided overwhelming evidence in support of IV rtPA plus mechanical thrombectomy for acute ische- mic stroke in patients with proximal large artery (ICA/MCA) compared to IV rtPA alone. In the studies, the odds of a favorable outcome (mRS 2 or less at 90 days) in the endovascular group were at least twice that in controls, without any difference in 30-day mortality or symptomatic ICH between groups. Furthermore, the benefit was maintained in old age (>80) and those with severe stroke (based on NIHSS). Further studies underway to assess its role in those with wake up strokes and those outside treatment timeframe as stratified by advanced imaging.
Which one of the following statements regarding stroke imaging is LEAST accurate?
a. ASPECT score of >7 is associated with unfavorable outcome with thrombolysis
b. Acute infarction is visible earlier on diffu- sion weighted imaging
c. MRI gradient echo (GRE) is useful for demonstrating microbleeds
d. CT/MR angiography can assess tissue perfusion
e. Prenumbra shows a normal or elevated regional cerebral blood volume, whereas this is reduced in infarcted tissue.
d. CT/MR angiography can assess tissue perfusion
Advance imaging in stroke has and increasing role in patient selection, and may be crucial in future to discriminate where endovascular therapy may be of benefit in those outside of established treat- ment windows or with wakeup strokes. Alberta Stroke Program Early Computed Tomography Score (ASPECTS) is a 10 point score used in MCA infarcts whereby 1 point is deducted for every vascular region involved. An ASPECT score of 7 or below is associated with a worse functional outcome at 3 months, higher risk of symptomatic hemorrhage and unfavorable out- come with thrombolysis. CT and MR angiogra- phy can demonstrate occlusion and length of clot and recanalization post-thrombolysis. MR gradient echo can demonstrate hemorrhage (and microhemorrhage), while DWI can demon- strate acute infarction very early on (e.g. 10 min in animal models). CT and MR perfusion imag- ing can be used to assess the proportion of sal- vageable (prenumbra) and non-salvageable (infarcted) tissue before deciding on endovascular therapy utilizing parameters shown below (TTP, MTT, CBF, CBV).
Which one of the following statements regarding randomized clinical trials comparing carotid endarterectomy to best medical therapy is LEAST accurate?
a. NASCET and ECST showed that the degree of benefit individual symptomatic patients gained from carotid endarterectomy was directly proportional to the risk they faced without surgery
b. Symptomatic male patients and those >70 years old benefit from CEA more
c. Risk of stroke recurrence at 30 days is 3% after first ever stroke
d. Patients with carotid “near-occlusion”
benefitted most from surgery
e. Carotid endarterectomy is 70-99%
carotid stenosis
d. Patients with carotid “near-occlusion”
benefitted most from surgery
The estimated 30-day risk of stroke recurrence after first stroke is $3% at 30 days and 26% at 5 years. The NASCET investigators stratified patients into groups with “low moderate” (<50%), “high moderate” (50-69%) and “severe” (70-99%) carotid stenosis. For the severe stenosis, the risk of any major stroke or death was 32.3% in the medical group and 15.8% in the surgical group at two years and sta- tistically significant. Furthermore, the degree of benefit individual symptomatic patients gained from carotid endarterectomy was directly pro- portional to the risk they faced without surgery: patients with 50-69% stenosis had attenuated benefit, therefore would be expected to face a lower risk without surgery. Patients with <50% stenosis did not achieve a significant reduction in the risk of ipsilateral stroke. In ECST, the method of measurement of carotid stenosis differed, but when the trial results were reanalyzed using the NASCET method, similar benefit for CEA was demonstrated. The five- year risk reduction of “stroke or surgical death” in ECST patients with 70-99% stenosis random- ized to CEA rather than medical treatment was 21.2%. In patients with 50-69% stenosis, the risk reduction was 5.7%. As expected, patients with a lesser degree of stenosis did not benefit from sur- gery. However, an additional important finding is that patients with “near-occlusion”—those with evidence of collapse of the distal vessel indi- cating poor run-off flow in the carotid—did not benefit significantly from surgery. Indeed, many patients with near-occlusion will progress to complete occlusion of the artery, which pre- cludes intervention. The risk/benefit ratio most favors surgery over medical treatment in men and in the elderly. In addition, the overall benefit of surgery is diminished as the time between symptoms and surgery increases, strongly argu- ing for intervention in the stable patient within two weeks of last symptoms. The rate of ipsilat- eral stroke in patients with asymptomatic carotid stenosis is much lower: possibly <0.5% per year in patients with !50% stenosis treated with best medical therapy. Two large randomized trials provide much of the data available to address the question of whether prophylactic CEA in the asymptomatic patient prevents stroke. The Asymptomatic Carotid Atherosclerosis Study (ACAS) randomized 1662 patients with an asymptomatic carotid stenosis of 60% or greater (measured using NASCET criteria) as detected on cerebral angiography or computerized tomography angiogram (CTA) either to daily aspirin with risk factor management (BMT) or to CEA plus BMT. CEA reduced the rate of rate of ipsilateral stroke or any perioperative stroke or death from 11.0% to 5.1%. The Asymptomatic Carotid Surgery Trial (ACST) randomized 3,120 patients with 60-99% carotid stenosis on Doppler ultrasound to either “immediate” end- arterectomy (with half of patients being operated on within one month after randomization) or deferral of CEA until a clinician considered there to be a clear indication for surgery. When perioperative adverse events were combined with subsequent strokes over a five-year period, CEA reduced the rate of events from 11.8% to 6.4% (p<0.0001) and subsequently main- tained at 10 year follow up in those operated <75. The results of these two trials, when com- bined in meta-analysis with the asymptomatic patients of the Veterans Affairs Cooperative Studies, appear to support the practice of endarterectomy for asymptomatic carotid stenosis to reduce the risk of ipsilateral stroke over three years but this risk reduction was marginal (6% reduction over 10 years) compared to that in symptomatic patients, and that to be worthwhile the surgical risk (MI, stroke, death) must be low and patient must also be prepared to incur an early risk of perioperative stroke to reduce the risk of a stroke that might not happen for many years. In subgroup analyses, surgical intervention appeared to benefit men more than women and younger patients more than older.
A 59-year-old man with a background of diabetes mellitus, hyperlipidemia, and hypertension presented with sudden left hemiparesis, hemisensory loss, and dysarthria due to right MCA infarct. He was treated with systemic thrombolysis and made some recovery. A carotid duplex ultrasound and CT angiogram of the carotid arteries confirmed a severe (70- 99%) stenosis in the right internal carotid artery (ICA) secondary to a 23-mm-long atherosclerotic plaque extending from the carotid bifurcation to the level of C3 verte- bral body with evidence of intraluminal thrombus. The left ICA showed moderate (50-69%) stenosis. Which one of the following is most appropriate?
a. Carotid endarterectomy
b. Carotid stent
c. Carotid angioplasty
d. Best medical therapy
e. EC-IC bypass
a. Carotid endarterectomy
Best medical therapy (BMT) alone may be pre- ferred for asymptomatic carotid occlusion if (i) patient life expectancy is less than the time to achieve stroke reduction benefit from revasculari- zation (i.e. 2-3 years for CEA, and 5 years for CAS), or (ii) if established periprocedure risk of death/stroke is small enough (<3%) and/or high future stroke risk factors (e.g. plaque ulceration, contralateral ICA occlusion, male, intraluminal thrombus, young age) to ensure benefit despite small absolute risk reduction seen in studies (6% at 5 years in ACAS). In contrast, symptomatic patients benefit almost immediately from CEA due to their higher short-term stroke risk. How- ever, even symptomatic patients with dense hemi- spheric neurological deficits, significant dementia, or severely limited functional status attributable to poor cardiac, renal, or pulmonary reserve are unlikely to benefit from any form of carotid revas- cularization. Factors outlining the decision between CEA and CAS in appropriate individuals with symptomatic carotid stenosis are shown below, although patient preference and operator experience/center specific outcomes are just as important.
Which one of the following randomized clin- ical trials comparing carotid endarterectomy and carotid artery stenting showed non- inferiority of carotid artery stenting to endar- terectomy in high-risk patients?
a. SAPPHIRE
b. EVA-3S
c. SPACE
d. ICSS
e. CREST
a. SAPPHIRE
Several large trials have shown the superiority of carotid endarterectomy to best medical manage- ment in patients with significant carotid stenosis (>70-99%) in terms of reducing risk of recurrent stroke. Many head to head trials of carotid end-arterectomy (e.g. EVA-3S, SPACE, ICSS) have failed to prove non-inferiority of CAS compared to CEA in standard risk patients. The CREST trial found CAS to be non-inferior to CEA in symptomatic or asymptomatic stan- dard risk patients, with no difference in rates of death, stroke or MI at 4 years (but did find a sta- tistically higher 30-day risk of stroke for CAS and MI for CEA). The Stenting and Angioplasty with Protection in Patients at High Risk for Endarter- ectomy (SAPPHIRE) trial, showed non- inferiority of CAS in high-risk patients at 3 years (e.g. clinically significant cardiac disease [conges- tive heart failure, abnormal stress test, or need for open-heart surgery], contralateral carotid disease, severe pulmonary disease). These results, have
meant that in symptomatic patients CAS is a viable option in high risk patients, those with stenosis distal to C2 vertebral body (difficult to treat with CEA), or if being performed by an experienced operator with established outcomes equivalent to CEA. Due to fewer trials demon- strating non-inferiority of CAS for asymptomatic patients, it should at present only be conside- red if being performed by an experienced operator with established outcomes equivalent to CEA.
Which one of the following statements regarding cerebral bypass grafts is LEAST accurate?
a. STA graft patency is >95% at 2 years
b. STA is a medium-high flow graft (initially
40-80 ml/min
c. Saphenous vein graft patency is 82% at
5 years
d. Initial flow through saphenous vein graft is 70-140 ml/min
e. High risk of vasospasm with radial artery interposition graft
b. STA is a medium-high flow graft (initially 40-80 ml/min)
Intravascular thrombosis is more likely when grasping the intima, if there is vessel stenosis at the anastomotic line (ideally fish mouthing required) or if the vessel is overly stretched. Main- taining patency is favored by fish mouthing the anastomosis in end to side grafts, using inter- rupted sutures to allow maximum expansion, and other factors such as flow demand through the bypass and length of the donor graft used in the bypass. Properties of common grafts are shown above.
