cerebrovascular disease for nurosurgical unitspptx

Neurology

1. Alebachew .A (BSc, MSc) Anesthesia for patients undergoing surgery for cerebrovascular disease February 21, 2024 PFS....

2. Outline Introduction Intracerebral aneurysm clipping Cerebral AV Malformations Carotid endarterectomy 2/21/2024 cerebrovascular disease 2

3. Introduction Stroke and cerebrovascular disease are the second leading cause of death worldwide and account for significant healthcare costs and morbidity among survivors ( WHO, 2014 ) Cerebrovascular disease consists of a group of conditions which can lead to a cerebrovascular accident, such as a stroke. Blockage, malformation, or hemorrhage prevents the brain cells from getting enough oxygen results brain damage These events affect the blood vessels and blood supply to the brain and involve both venous and arterial circulations. 2/21/2024 cerebrovascular disease 3

4. 1.Intracerebral aneurysm Aneurysms are thought to arise from turbulent blood flow at arterial branching points, causing “sac-like” or “fusiform” dilatations to occur. CA; is a ballooning arising from a weakened area in the wall of blood vessels in the brain Most cerebral aneurysms (80–85%) are located in the anterior circulation and are more prone to rupture when larger than 7 mm. Cerebral aneurysms most commonly occur at the anterior communicating arteries (40%), PCOMs (25%), and MCA (25%), with only 10% arising from the vertebrobasilar system. ( Lecours M, Gelb AW.2014 ) 2/21/2024 cerebrovascular disease 4

5. Cont.…. Affects 1-2% of population Accounts for 80-85% of non-traumatic subarachnoid hemorrhage (SAH) 1-year risk of rupture: 1-4%; 5-year risk of rupture: 3-4 % ( Catalin Ezaru, 2018 ) 2/21/2024 cerebrovascular disease 5

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7. Cont.. Cerebral aneurysms typically occur at the bifurcation of the large arteries at the base of the brain; most are located in the anterior circle of Willis . The incidence rate of aneurysmal subarachnoid hemorrhage is approximately 10 per 100,000. Subarachnoid hemorrhage is fatal in >25% of the cases and >50% of the survivors have persistent neurological deficits. ( Feigin VL etal,2009 ) 2/21/2024 cerebrovascular disease 7

8. Unruptured Aneurysms Patients may present with early symptoms and signs suggesting progressive enlargement. The most common symptom is headache , and the most common physical sign is a third-nerve palsy . Other manifestations include brainstem dysfunction, visual field defects, trigeminal nerve dysfunction, seizures, and hypothalamic–pituitary dysfunction. Most patients are in the 40- to 60-year-old age group and in otherwise good health. 2/21/2024 cerebrovascular disease 8

9. Ruptured Aneurysms Ruptured aneurysms usually present acutely as subarachnoid hemorrhage. During the initial bleeding, blood can spread through the subarachnoid space, but with rebleeding, intracranial hemorrhage is more common and can be intraparenchymal (20%–40%), intraventricular (10%–20%), or subdural (5%). Ruptured aneurysms are the most common cause of spontaneous SAH, accounting for 80% of nontraumatic SAH. Patients may present with severe headache , nausea and vomiting, photophobia, seizures, focal neurologic deficits, and altered consciousness. If ICP does not decrease rapidly after the initial sudden increase, death usually follows . 2/21/2024 cerebrovascular disease 9

10. Cont.… Risk Factors for Aneurysm Development and Rupture Age > 50 Sex: F > M Hypertension Cigarette smoking History of SAH Aneurysm size (large [> 10 mm] or giant [> 25 mm]) Aneurysm location (posterior > anterior for rupture) ( Brown RD Jr, Broderick JP, 2014 ) 2/21/2024 cerebrovascular disease 10

11. Cont.. The pathophysiologic changes that occur when an aneurysm ruptures include: • A sudden large increase in ICP • A decrease in CBF, which may help stop further bleeding • Cerebral vasoconstriction • Loss of cerebrovascular autoregulation • A decrease in CPP • Spread of blood through the subarachnoid space causing inflammation February 21, 2024 PFS....

12. Grading of SAH Hunt and Hess grading scale for SAH . World Federation of Neurological Surgeons Grading scale for aneurismal SAH. 2/21/2024 cerebrovascular disease 12

13. Complications Rebleeding : The incidence of rebleeding is approximately 8% and is highest in the first 72 h. Vasospasm : The pathogenesis involves the break-down products of hemoglobin released around the Circle of Willis, starts on day 3 after SAH, peaks at days 7–10 and ends at day 21. ( Conolly ES Jr, 2012 ) Nimodipine is recommended by AHA for all patients with aSAH for vasospasm prophylaxis. Triple-H therapy (hypertension, hypervolemia, and haemodilution) : to increase CBF, increase CPP, and improve the rheological blood characteristics. 2/21/2024 cerebrovascular disease 13

14. Cont.… Cardiac dysfunction : responsible mechanism is believed to be a catecholamine surge leading to subendocardial necrosis. ECG abnormalities (ST segment depression, wave inversion, prolonged QT interval, U waves) have been described in 25–90% of subarachnoid hemorrhages. ( Coghlan LA.etal,2009 ) Hyponatremia : Two main causes are : cerebral salt wasting syndrome and syndrome of in appropriate ADH secretion ( Rahman M, Friedman WA.2009 ) 2/21/2024 cerebrovascular disease 14

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16. Goals of anesthesia Four principles guide anesthetic management: Minimize any change in the aneurysm transmural gradient (MAP minus local ICP) Maintain adequate cerebral perfusion pressure. Provide brain relaxation Allow a fast and smooth emergence ( Lecours M, Gelb AW.2014 ) 2/21/2024 cerebrovascular disease 16

17. Preoperative Assessment Patients need to be assessed for the presence and extent of all intracranial and extracranial complications of a SAH The preoperative assessment should include a complete history, physical examination with special focus on the neurological evaluation, and a review of important imaging studies It is essential to optimize cardiac, pulmonary, and metabolic function before induction of anesthesia Medical therapy for coexisting conditions should be continued, and patients should be maintained on nimodipine and anticonvulsant medications Premedication may be appropriate in good-grade patients but should be avoided in general. February 21, 2024 PFS....

18. Monitoring routine cardiac, respiratory, urine output, and nasopharyngeal temperature monitoring, direct measurement of intra-arterial blood pressure and CVP Intraoperative cerebral monitoring; jugular bulb or cerebral oximetry, transcranial doppler measurement of CBF velocities, EEG, and evoked potentials. Blood analysis February 21, 2024 PFS....

19. Induction of Anesthesia Intravenous induction of anesthesia via a large-bore cannula is the most common technique used. Wide swings in either MAP or ICP will alter the TPG (TPG = MAP − ICP) across the aneurysm and may cause it to rupture Laryngoscopy, intubation, and the application of skull pins are potent hypertensive stimuli Intravenous or topical lidocaine, β-blockers, short-acting opiates or intravenous induction agents can be used to facilitate this. MAP should then be maintained within 20% of the patient’s normal preoperative level to achieve an adequate CPP. February 21, 2024 PFS....

20. Maintenance using inhalational agents or TIVA. Short acting drugs such as propofol, fentanyl, remifentanil or sufentanil are commonly used Methods to reduce the volume of intracranial contents by using hyperosmolar agents (mannitol or hypertonic saline), moderate hyperventilation, and drainage of CSF may adversely alter the TPG and should be initiated slowly or ideally, delayed until the dura is open February 21, 2024 PFS....

21. Cont.. Temporary arterial occlusion & brain protection surgeons may use temporary occlusion of the proximal artery to facilitate dissection and clipping. To minimize the risk of focal brain ischemia, the period of occlusion should be minimized by a skilled surgeon. A 10 min occlusion seems to be safe while more than 20 min of occlusion is associated with poor outcomes. (Lecours M, Gelb AW.2014) 2/21/2024 cerebrovascular disease 21

22. Emergence patients should be extubated with minimal coughing and hemodynamic fluctuations. Uncontrolled hypertension or persistent hypotension requires treatment to prevent adverse cerebral or cardiac sequela February 21, 2024 PFS....

23. Postoperative Anesthetic Care Neurovascular patients should be managed in a neurosurgical high-dependency or intensive care unit to ensure continued hemodynamic monitoring, adequate oxygenation, optimum fluid and electrolyte management, and early detection of complications Analgesics, including small doses of opiates In patients at increased risk of cerebral vasospasm, a 10%–20% increase in MAP above preoperative baseline values may be of benefit. February 21, 2024 PFS....

24. Intraoperative rupture (IAR) Intraoperative factors contributing to IAR Hypertension Anesthetic factors -Sympathetic responses, light anesthesia ICP: Sudden decrease in ICP Maneuvers Valsalva, application of PEEP (upper limit) Comorbidities : COPD, CAD, and hyperlipidemia ( Chowdhury.T etal, 2014 ) 2/21/2024 cerebrovascular disease 24

25. Diagnosis of IAR 2/21/2024 cerebrovascular disease 25

26. Management 2/21/2024 cerebrovascular disease 26

27. 2.Cerebral AV Malformations AVM are defects in cerebral vasculature development leading to the formation of shunts between the high-pressure arterial and the low-pressure venous systems without an intervening normal capillary bed. brain arteriovenous malformation (AVM) is a tangle of blood vessels that connects arteries and veins in the brain. The incidence of symptomatic AVMs is estimated to be 0.82–1.1 per 100,000 population. AVMs are usually detected between the ages of 10 and 40 years, with approximately 70% being supratentorial ( Rutledge WC,2014 ) 2/21/2024 cerebrovascular disease 27

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29. Cont.. The primary characteristic of cerebral circulation in patients with untreated AVMs is the diversion of flow thorough the path of least resistance (the AVM itself), bypassing the normal arteriolar and capillary system in the adjacent normal tissue. This can lead to chronic cerebral hypotension and potential for ischemia (cerebral steal). 2/21/2024 cerebrovascular disease 29

30. Signs and Symptoms The most common presentations of AVMs are: Intracranial hemorrhage Intraventricular hemorrhage Seizures Headache and tinnitus Focal neurological deficits Weakness, numbness or paralysis Vision loss Difficulty speaking Confusion or inability to understand others 2/21/2024 cerebrovascular disease 30

31. Cont.. predictors of subsequent hemorrhage Increasing age, initial hemorrhage presentation, deep brain location, and exclusive deep vein drainage Complication Bleeding in the brain Reduced oxygen to brain tissue Thin or weak blood vessels Brain damage. February 21, 2024 PFS....

32. Grading of AVMs Spetzler and Martin grading system This is used to predict the surgical outcome but can also stratify AVMs for radiosurgical , endovascular, or combined therapy. This is based on size, pattern of venous drainage, and eloquence of adjacent brain 2/21/2024 cerebrovascular disease 32

33. Treatment Options The primary rationale to treat AVMs with invasive therapy is for the prevention of new or recurrent intracranial hemorrhage. There are three treatment options for AVM: Endovascular embolization, Radiosurgery Microsurgical excision. The main goals for treatment of AVMs are protection against ICH and maximizing the neurological function . 2/21/2024 cerebrovascular disease 33

34. cont.… preoperative embolization : occlude vessels that may be difficult to control surgically thereby facilitating AVM excision and reducing blood loss. Radiosurgery : involves the precise delivery of radiation to the target using a stereotactic frame leading to endothelial cell proliferation and progressive closure of the vessels. Surgical excision: is indicated for accessible lesions preferably located in noneloquent areas (low grade as defined by Spetzler -Martin scale) and is commonly preceded by endovascular embolization. 2/21/2024 cerebrovascular disease 34

35. Anesthetic Management Preoperative Evaluation Factors to be considered include: size of AVM (potential for blood loss), location of AVM (eloquent brain areas), The potential impact of neurologic dysfunction, Neurophysiologic monitoring and vascular access . 2/21/2024 cerebrovascular disease 35

36. Intraoperative Management Avoidance of acute hypertension still remains a fundamental goal for any neurovascular procedure in order to minimize the risk of bleeding and brain edema Maintenance of CPP to ensure adequate perfusion and collateral flow, and good brain relaxation to facilitate surgical access and minimize retractor pressures are the main goals of intervention. 2/21/2024 cerebrovascular disease 36

37. Role of Induced Hypotension Induced hypotension has to be used with caution. While it can control bleeding particularly during resection of large AVMs, it can also cause cerebral ischemia. In the event of uncontrolled and profuse bleeding during surgery the anesthesiologist may administer barbiturates along with mild to moderate systemic hypotension to facilitate clip placement to control the bleeding. Following resection of the AVM, surgical hemostasis is confirmed by briefly elevating the BP to 20–30% of baseline values. February 21, 2024 PFS....

38. POSTOPERATIVE MANAGEMENT hemorrhage and brain edema can occur not only during the emergence phase but also for the first few days postoperatively. during emergence from anesthesia and for the first 8 postoperative days, the BP be controlled within 10% of preoperative values. February 21, 2024 PFS....

39. carotid artery stenosis The carotid arteries are the main blood vessels that carry blood and oxygen to the brain. When these arteries become narrowed Up to 20% of all ischemic strokes are caused by an occlusion of the extracranial part of the ICA. The two routinely performed procedures for carotid artery stenosis are carotid endarterectomy (CEA) and carotid artery stenting (CAS) Carotid endarterectomy (CEA) is performed to prevent embolic stroke in patients with atheromatous disease at the carotid bifurcation . 2/21/2024 cerebrovascular disease 39

40. Anatomy The brain receives its blood supply from four major arteries 80-90 % of the cerebral blood supply is delivered via the two internal carotid arteries and the remainder coming from the vertebrobasilar system The carotid arteries and basilar artery unite to form the Circle of Willis at the base of the brain. The Circle of Willis is incomplete in 15% of normal people and in patients with cerebrovascular disease one or more of the vessels within the circle maybe occluded by atheromatous plaque. 2/21/2024 cerebrovascular disease 40

41. 3.CEA CEA is strongly recommended in patients with stenosis degree of 70%-99% when symptoms occurred within the last 6 months In cases of a 50%- 69% ICA stenosis, for surgical intervention are not recommended. Symptomatic stenosis of less than 50% is no reliable indicator for CEA. 2/21/2024 cerebrovascular disease 41

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43. Cont.. Carotid artery disease can lead to stroke through: Reduced blood flow . A carotid artery might get so narrow because of atherosclerosis that not enough blood reaches parts of the brain. Ruptured plaques . A piece of a plaque can break off and travel to smaller arteries in the brain. The piece of plaque can get stuck in one of these smaller arteries. This blockage cuts off blood supply to part of the brain. Blood clot blockage. Some plaques are prone to cracking and forming irregular surfaces on the artery wall February 21, 2024 PFS....

44. Preoperative Assessment The aims of preoperative assessment of patients presenting for CEA include: risk stratification, evaluation of the benefits and risks of revascularization, optimization of pre-existing medical conditions, identification of cardiac conditions or risk factors that warrant management, and formulation of an anesthetic plan. February 21, 2024 PFS....

45. Preoperative Evaluation Patients with carotid artery stenosis are usually suffering from multiple comorbid conditions, and preoperative control is desirable. Hypertension is present in 65% of CEA patients The prevalence of coronary disease in the patients presenting for CEA is as high as 77%. DM may be present in patients with carotid artery disease, and the preoperative blood sugar control with absence of ketoacidosis is essential. 2/21/2024 cerebrovascular disease 45

46. Cont.. Neurological assessment should evaluate the risk of perioperative stroke. Other comorbidities such as hypertension, chronic obstructive lung disease, and renal impairment which are common. Antiplatelet medications, especially aspirin, should be continued throughout the perioperative period for prevention of postoperative carotid thrombosis. Other medications such as statins, anti-anginal, and anti-hypertensive medications including beta-blocking drugs should be continued preoperatively February 21, 2024 PFS....

47. Monitoring The main purpose of neuromonitoring in patients of CEA is to detect cerebral ischemia early. Commonly used monitoring techniques include electroencephalography (EEG) evoked potential monitoring, transcranial Doppler (TCD), jugular venous oxygen saturation (SjvO2), carotid stump pressure (CSP) monitoring, brain tissue oxygen (PtiO2) monitoring. 2/21/2024 cerebrovascular disease 47

48. GA vs regional for CEA 2/21/2024 cerebrovascular disease 48

49. Anesthetic Goals The primary anesthetic goals include: maintenance of strict hemodynamic control to promote cerebral perfusion and CBF, avoidance of secondary insults to the brain (e.g., hypoglycemia, hyperthermia, hypoxia), and vigilance for potential perioperative complications, especially cardiac ischemia and neck hematoma SBP should be aggressively maintained at the patient’s baseline level or slight hypertension (within 20% of baseline) completion of the endarterectomy and re-establishment of cerebral circulation) maintenance of normocarbia is recommended February 21, 2024 PFS....

50. Intraoperative Fluctuations in blood pressure and heart are common during the carotid endarterectomy. Dilatation of the carotid artery and stimulation of the carotid baroreceptors can cause bradycardia and hypotension, and Rescue treatment with glycopyrrolate or atropine increasing the depth of anesthesia along with infiltration of LA agent around the carotid sheath. The main aim of anesthetic management in CEA is prevention of any adverse cerebral or coronary events 2/21/2024 cerebrovascular disease 50

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53. Postoperative Concerns Post-procedure, the patient must be watched for cerebral hyperperfusion following restoration of normal CBF. ipsilateral headache, hypertension, seizures, and focal neurological deficits After the procedure, combined platelet inhibition with clopidogrel and aspirin is continued for at least 30 days and up to 12 months ( Behrbalk E, et al.2012 ) Common postoperative complications include the dysfunction of the carotid chemoreceptors and the baroreceptor , cerebral hyperperfusion syndrome, stroke, myocardial infarction, and death Hematoma at the surgical site and cranial nerve palsies secondary to intraoperative manipulation. 2/21/2024 cerebrovascular disease 53

54. Reference Textbook of Neuroanesthesia & Neurocritical Care Paul G. Barash 8 th edition Smith and Aitkenhead's Textbook of Anaesthesia Catalin Ezaru, Anesthetic Considerations for Surgical Resection of Brain Arteriovenous Malformations, 2018 Tumul Chowdhury, etal. Controversies in the Anesthetic Management of Intraoperative Rupture of Intracranial Aneurysm Malcharek : Carotid endarterectomy, DOI: https://doi.org/10.1016/B978-0-12-815000-9.00025-3 2/21/2024 cerebrovascular disease 54

55. Thanks a lot 2/21/2024 cerebrovascular disease 55