Ebook Textbook of neurointensive care (2/E): Part 2

(BQ) Part 2 book Textbook of neurointensive care has contents: Diagnosis and treatment of altered mental status, complex spine surgery, elevated intracranial pressure, neuroradiological imaging, intraoperative neuroanesthesia, ethical issues in the neurointensive care unit,... and other contents.

Aneurysmal Subarachnoid Hemorrhage: Evidence-Based Medicine, Diagnosis, Treatment, and Complications 24 Matthew M Kimball, Gregory J Velat, J.D Mocco, and Brian L Hoh Contents Abstract Introduction 541 Natural History of Aneurysmal SAH 542 Diagnosis and Initial Management Presentation Initial Evaluation and Imaging Contrast Prophylaxis 542 542 542 545 Initial Stabilization and Management Antifibrinolytics Seizures Hydrocephalus 546 547 547 548 Treatment Methods for Ruptured Cerebral Aneurysms 548 Surgical Treatment Options 548 Endovascular Treatment 550 Cerebral Vasospasm and SAH 551 Modalities for Identifying Cerebral Vasospasm 551 Vasospasm Prophylaxis and Management 552 Medical Complications of Subarachnoid Hemorrhage Cardiac and Pulmonary Complications Anemia and Transfusion Hyponatremia 556 556 557 558 Aneurysmal subarachnoid hemorrhage is a devastating condition with high mortality and morbidity rates for those that survive the initial hemorrhage There has been significant research on aneurysmal subarachnoid hemorrhage to better understand how we can diagnose, treat, and manage patients with this disease Cerebral vasospasm accounts for the majority of morbidity, mortality, and long-term disability in these patients, and a large volume of literature is dedicated to preventing and treating vasospasm This chapter presents a simplified, evidence-based review of the literature about the modes of diagnosis, medical and surgical management, and treatment options of patients with aneurysmal subarachnoid hemorrhage and cerebral vasospasm Keywords Cerebral aneurysm • Cerebral vasospasm • Evidencebased treatment • Hydrocephalus • Subarachnoid hemorrhage References 559 Introduction M.M Kimball, MD • B.L Hoh, MD, FACS, FAHA, FAANS (*) Department of Neurological Surgery, University of Florida College of Medicine, 100265, Gainesville, FL 32610, USA e-mail: matthew.kimball@neurosurgery.ufl.edu; brian.hoh@neurosurgery.ufl.edu G.J Velat, MD Department of Neurosurgery, Lee Memorial Hospital, Fort Myers, FL 33901, USA e-mail: gvelat@gmail.com J.D Mocco, MD, MS, FAANS, FAHA Department of Neurosurgery, Vanderbilt University Medical Center, 1161 21st Ave S, RM T4224 MCN, Nashville, TN 37232, USA e-mail: j.mocco@vanderbilt.edu A.J Layon et al (eds.), Textbook of Neurointensive Care, DOI 10.1007/978-1-4471-5226-2_24, © Springer-Verlag London 2013 Aneurysmal subarachnoid hemorrhage (SAH) is a devastating condition accounting for about % of all strokes, affecting about 30,000 people in the United States every year [1, 2] The annual prevalence of aneurysmal SAH is likely higher than 30,000 due to misdiagnosis and those who not receive medical care The incidence of aneurysmal SAH varies around the world and has been reported anywhere from to 23 per 100,000 [3, 4] Mortality rates range from 32 to 67 % [5] with a significant degree of morbidity among those who survive the initial hemorrhage [6, 7] Recent data have shown that there may be a declining mortality rate after aneurysmal SAH with more recent treatment modalities [8] However, despite many advancements such as endovascular therapy for the treatment of 541 542 aneurysms and the ability to better diagnose and treat cerebral vasospasm, morbidity remains high Aneurysmal SAH typically affects adults in the fifth to seventh decades of life and is about 1.6 times more common in females than in males [9, 10] Some genetic syndromes have a higher risk of aneurysm formation and hemorrhage, such as polycystic kidney disease [11] and Ehlers-Danlos [12] syndrome Familial intracranial aneurysm syndrome is when two or more first- through third-degree relatives are found to have intracranial aneurysms Those who have this syndrome are more inclined to harbor multiple intracranial aneurysms and experience aneurysmal SAH at a younger age [13] Additional risk factors for developing aneurysmal SAH include hypertension, smoking history, and alcohol abuse all of which have been validated on multivariate analyses [14, 15] Cocaine use and other sympathomimetics have also been shown to increase risk of SAH, particularly in younger patients with SAH [16] M.M Kimball et al Institutional factors included availability of endovascular services, volume of SAH patients treated at a given institution, and the type of facility in which the patient is first evaluated Rebleeding after the initial hemorrhage carries a very high mortality rate of approximately 70 % and is highest in the first 24–48 h [25] The International Cooperative Study on the Timing of Intracranial Aneurysm Surgery [26] found that patients who underwent aneurysm treatment in 100,000 RBC/mm3 (little change between first and last tube) Xanthochromia (yellow/pink) Xanthochromia Usually does not clot Slight leukocytosis Commonly elevated Commonly elevated Magnetic resonance imaging is currently of little diagnostic value for acute aneurysmal SAH due to poor sensitivity to detect methemoglobin molecules in the first 24–48 h following rupture Patient compliance, duration of time needed to obtain the scan, and increased cost compared to CT scanning have relegated MR imaging in the diagnosis of aneurysmal SAH Magnetic resonance angiography (MRA) may be used in patients with renal insufficiency, acute renal failure, or pregnant patients to diagnose intracranial aneurysms with reduced sensitivity and specificity compared to CT angiography (CTA) MRA sensitivity ranges from 85 to 100 % for aneurysms >5 mm but drops to approximately 56 % for aneurysms ≤5 mm [34, 35] MRI and MRA may be helpful when looking for other causes of SAH such as cervical spinal arteriovenous malformations that may be missed by conventional CTA The most useful noninvasive imaging modality in acute SAH is CTA (Fig 24.1b) It can be obtained quickly, provides excellent three-dimensional reconstructions, shows relationship of aneurysms to bony landmarks, may show thrombus or calcification within the aneurysm, is noninvasive, and has a high sensitivity and specificity Sensitivity of CTA for aneurysms ranges from 95 to 100 % for aneurysms ≥5 mm but drops off to 64–83 % for aneurysms ≤5 mm [36–38] CTA sensitivity diminishes with small aneurysms, increased blood products, and may vary in accordance with experience of the interpreting neuroradiologist Potential disadvantages of CTA include the inability to adjust the contrast dose and/or concentration for patients at risk of renal dysfunction, artifact from previous aneurysm clips or embolic material may obstruct aneurysm diagnosis, and small distal vessels may not be well visualized Currently, CTA is the diagnostic imaging study of choice for initial detection of intracranial aneurysms Cerebral angiography, the traditional gold standard diagnostic test for intracranial aneurysms, is typically performed if CT angiography fails to reveal a potential bleeding source Cerebral angiography holds many advantages over other diagnostic imaging techniques First, it allows for methodical evaluation of the intracranial vasculature via selective injection of intracranial arteries PA and lateral projections are obtained simultaneously to better characterize the exact Traumatic tap RBC should decrease between first and last tube Bloody Clear Typically clots Same as peripheral blood Commonly normal May be elevated slightly location and morphology of intracranial aneurysms (Fig 24.1c) Three-dimensional reconstructions can be readily obtained In addition, cerebral vasculature surrounding an intracranial aneurysm is delineated Endovascular intervention may be pursued at the time of cerebral angiography, effectively streamlining aneurysm treatment Contrast load can also be altered, which may benefit patients with renal insufficiency Despite the improved sensitivity of cerebral angiography for the diagnosis of intracranial aneurysms or other vascular malformation causing SAH, in about 20–25 % a source of hemorrhage will not be found Many centers repeat a diagnostic cerebral angiogram week after the initial angiogram to evaluate for a small aneurysm that was unable to be visualized on the initial study In about 1–2 % of patients, an aneurysm is found after repeat angiogram [39] It is controversial whether the small percentage of aneurysms found on repeat angiography warrants a repeat angiogram on all patients with a single negative diagnostic cerebral angiogram We feel that the small morbidity of a diagnostic cerebral angiogram of about 1–2 % versus the morbidity and mortality of a re-ruptured undiagnosed aneurysm warrants a repeat angiogram Contrast Prophylaxis The number of diagnostic and therapeutic spinal and cerebral angiograms has gone up exponentially in the last 20 years and therefore the use of iodinated contrast media Although newer and safer contrast media have been developed and used over recent years, we need to understand the risks of using these agents The majority of the literature on these agents comes from the cardiology literature where there is a much higher patient population to study Low-osmolality agents have been in use since the 1980s and have had a direct reduction in the pain associated with administration as well as adverse events These agents have been proven to be safe but are associated with a small percentage of adverse reactions ranging from rash and flushing to angioedema, vasomotor collapse, and death The risk for adverse reactions increases with higher osmolarity and ionicity The risk for all adverse reactions ranges from to 12 % with ionic agents 546 compared to 1–3 % with nonionic agents [40] The risk for severe reactions such as anaphylaxis and vasomotor collapse was significantly lower for low-osmolality agents 0.03 % compared with 0.16 % for high-osmolality agents [41] The strongest risk factors for predicting an adverse reaction to contrast are a previous history of contrast reaction and atopic conditions such as asthma A previous history of a contrast reaction gives a 17–35 % risk of future reaction [42] Asthma increases the risk of reaction by approximately six times the general population [43] Other risk factors reported for contrast reactions include underlying heart disease, renal disease, diabetes mellitus, myeloma, sickle cell disease, polycythemia, food or medication allergies, hay fever, nonsteroidal anti-inflammatory drug use, beta-blocker use, age greater than 60, and female gender [44] There has been a long debated argument as to risk of a contrast reaction in a patient with a known shellfish allergy There has never been a reported case of shellfish allergy where iodine was implicated, and the reaction to radiocontrast media has never been proven to be related in any way to the iodine content in a preparation Routine premedication for contrast reaction prior to contrast is not supported by the evidence currently available in the literature for those with shellfish allergy Two major prophylaxis regimens are approved by the American College of Radiology and include: Pretreatment Protocol 1: (a) Prednisone 50 mg orally 13, 7, and h prior to procedure (b) Diphenhydramine 25–50 mg intravenously, intramuscularly, or orally h prior to procedure (c) Nonionic low-osmolality contrast medium Pretreatment Protocol 2: (a) Methylprednisolone 32 mg orally 12 and h prior to procedure (b) Diphenhydramine 25–50 mg intravenously, intramuscularly, or orally h prior to procedure (c) Nonionic low-osmolality contrast medium The use of these preventative protocols has reduced the incidence of severe reactions and should be used in the appropriate populations In the instance that waiting the 12–13 h is not reasonable for diagnosis or treatment by CTA or cerebral angiogram, a single dose of 100 mg of hydrocortisone sodium succinate can be given intravenously at the time of the procedure Initial Stabilization and Management The patient should be transferred out of the emergency medical setting to a neurosurgical ICU setting as soon as possible The admission Hunt-Hess grade (Table 24.2), Fisher score (Table 24.3), and World Federation of Neurologic Surgeons (WFNS) grade (Table 24.4) should also be reported, as it M.M Kimball et al Table 24.2 Hunt-Hess classification Grade Description Asymptomatic or minimal headache and slight nuchal rigidity Moderate to severe headache, nuchal rigidity, no neurologic deficit except cranial nerve palsy Drowsy, minimal neurologic deficit Stuporous, moderate to severe hemiparesis, early decerebrate rigidity Deep coma, decerebrate rigidity, moribund Reproduced with permission from Hunt and Hess [45] Table 24.3 Fisher score Fisher grade Appearance of blood on CT scan No hemorrhage evident Subarachnoid hemorrhage less than mm thick Subarachnoid hemorrhage more than mm thick Subarachnoid hemorrhage of any thickness with intraventricular hemorrhage or intraparenchymal hemorrhage Modified with permission from Fisher et al [46] Table 24.4 World Federation of Neurologic Surgeons (WFNS) grade WFNS grade Glasgow coma score Major focal deficit 15 13–14 13–14 7–12 3–6 No No Yes Yes or no Yes or no Reproduced with permission from Drake [47] may aid treatment, prognosis, and risk of vasospasm The Airway management, breathing, and hemodynamic stability are the first priority All of these should be managed with the understanding that manipulation of the airway may induce gag or cough reflexes, elevations in PCO2, and intubation may elevate blood pressure, acutely placing the patient at high risk for rebleeding Preoxygenation should be done prior to intubation The gag and cough reflex, and reflex cardiac dysrhythmias can be avoided by appropriate pharmacologic agents Although bed rest and a low-stimulation environment have been accepted as common management for an unsecured aneurysm, there are no data to support that it lowers the risk of early rebleeding; however, it causes no harm to the patient and should probably be followed There is a large amount of literature in regard to treatment of hypertension in the acute period for an unsecured aneurysm; however, no well-controlled studies have been done to show that strict blood pressure control has any effect on rebleeding rates A retrospective study has shown that there appears to be a lower risk of rebleeding in those treated with 24 Aneurysmal Subarachnoid Hemorrhage: Evidence-Based Medicine, Diagnosis, Treatment, and Complications 547 antihypertensive medications, but in this study those treated had higher blood pressures than those not treated, and there did not appear to be a correlation with a lower blood pressure [48] Another study had stated that rebleeding may be related to greater variations in blood pressure and not an absolute value [49] A specific goal systolic blood pressure (SBP) remains controversial and variable, but most would agree that a SBP goal