Subarachnoid Hemorrhage ======================= þ No need for LP for ? SAH if: - 3rd generation CT is negative for SAH - HA onset within 6 hours [Perry, J. J., I. G. Stiell, et al. (2011). "Sensitivity of computed tomography performed within six hours of onset of headache for diagnosis of subarachnoid haemorrhage: prospective cohort study." Bmj 343(jul18 1): d4277- d4277.] þ When to Stop the Work-up? - In patients with acute, severe headache and normal neurological examinations, CT scans, and CSF analysis, is further evaluation necessary? The vast majority of such patients have excellent outcomes. In one retrospective study of 71 patients, none had SAH during an average follow-up of 3.3 years (136). Furthermore, in four prospective studies (totaling 254 patients) followed for over 1 year, none had subsequent SAH or sudden death (9,137–139). This evidence strongly suggests that most patients with normal CT and CSF examinations do not require angiography. The occasional patient whose clinical presentation suggests cranial artery dissection, cerebral venous sinus thrombosis, or pituitary apoplexy may require further imaging. [Edlow, J. A., A. M. Malek, et al. (2008). "Aneurysmal subarachnoid hemorrhage: update for emergency physicians." The Journal of emergency medicine 34(3): 237-251.] Aneurysmal subarachnoid hemorrhage (SAH) is a serious cause of stroke that affects 30,000 patients in North America annually. Due to a wide spectrum of presentations, misdiagnosis of SAH has been reported to occur in a significant proportion of cases. Headache, the most common chief complaint, may be an isolated finding; the neurological examination may be normal and neck stiffness absent. Emergency physicians must decide which patients to evaluate beyond history and physical examination. This evaluation--computed tomography (CT) scanning and lumbar puncture (LP)--is straightforward, but each test has important limitations. CT sensitivity falls with time from onset of symptoms and is lower in mildly affected patients. Traumatic LP must be distinguished from true SAH. Cerebrospinal fluid analysis centers on measuring xanthochromia. Debate exists about the best method to measure it-- visual inspection or spectrophotometry. An LP-first strategy is also discussed. If SAH is diagnosed, the priority shifts to specialist consultation and cerebrovascular imaging to define the offending vascular lesion. The sensitivity of CT and magnetic resonance angiography are approaching that of conventional catheter angiography. Emergency physicians must also address various management issues to treat or prevent early complications. Endovascular therapy is being increasingly used, and disposition to neurovascular centers that offer the full range of treatments leads to better patient outcomes. Emergency physicians must be expert in the diagnosis and initial stabilization of patients with SAH. Treatment in a hospital with both neurosurgical and endovascular capability is becoming the norm. þ Modern (2004) CT sensitivity (University of Ottowa, SAEM 2004): - Second- and Third-generation CT scanners only about 80% sensitive. - SAH was 8.1%, 0.4% other bleed, 0.6% tumor, small percentage of meningitis - 3% misdiagnosed initially, overread positive (CTs initally ready by EPs) - 93% sensitive overall HA less than 6 hours: 100% sensitive (confidence intervals 92-100%), specificity 100% HA more than 6 hours: 84% - Good CT, HA less than 6 hours, no signs of meningitis: no need for LP [Perry J. The sensitivity of computed tomography for the diagnosis of subarachnoid hemorrhage in ED patients with acute headache.] þ Anatomy and Neurology - 1% of population have asymptomatic aneurysm - 85% anterior aneurysms - blown pupil only with posterior aneurysms - most anterior aneurysms have normal exams or subtle visual field cuts. þ CT findings - if SAH from trauma, but blood at basilar cisterns, must check for aneurysm. þ "Sentinel Headache" - small SAH þ Classic vs. Non-Classic Presentation: - classic: sudden, severe first headache - non-classic: change in usual headaches þ SAH mortality - about 50% at 30 days. þ SAH Grading AANS 1 - normal mental status, no neuro deficits, mild headache, no meningeal signs 2 - mildly altered mental status, focal deficit, severe headache, + meningeal signs 3 - major alterations in consciousness or major focal deficit 4 - semicomatose or comatose Hunt and Hess scale: 1 - Asymptomatic or mild HA 2 - Moderate-to-Severe HA, nuchal rigidity, and no neurological deficit other than possible cranial nerve palsy 3 - Mild alteration in mental status (confusion, lethargy), mild focal neuro deficit 4 - Stupor and/or hemiparesis 5 - Comatose and/or decerebrate rigidity WFNS 1 - GCS 15, no motor deficit 2 - GCS 13-14, no motor deficit 3 - GCS 13-14, + motor deficit 4 - GCS 7-12, +/- motor deficit 5 - GCS 3-6, +/- motor deficit Fischer Scale (CT scan appearance) 1 - no blood seen 2 - Diffuse deposition of subarachnoid blood, no clots, no layers of blood more than 1 mm 3 - Localized clots and/or vertical layers of blood 1 mm or greater in thickness 4 - Diffuse or no subarachnoid blood, but + intracerebral or intraventricular clots Hunt and Hess and WFNS correleate well with outcome. Fischer scale predicts vasospasm. þ Delayed problems with SAH: - rebleeding + because the body's normal fibrinolytic mechanism dissolves the clot that limits the bleed in the first place. + This is the rationale behind the use of anti-fibrinolytic agents such as AMICAR. Unfortunately this works better in theory than in practice and anti-fibrinolytics have their own set of problems which limit their usefulness in this setting. A randomized prospective multicenter trial using short-term tranexamic acid suggested that this strategy reduced rebleeding without increasing vasospasm or clinically significant cerebral ischemia. [Hillman J, Fridriksson S, Nilsson O, Yu Z, Saveland H, Jakobsson KE. Immediate administration of tranexamic acid and reduced incidence of early rebleeding after aneurysmal subarachnoid hemorrhage: a prospective randomized study. J Neurosurg 2002;97:771– 8.] - vasospasm + causes symptoms of ischemic stroke typically either in the 1st day with a secondary peak 1 week later. + rationale behind using nimodipine is to prevent vasospasm although in reality it does not appear to lessen the extent of vasospasm seen on angiography. It probably exerts its protective effects by deceasing *neuronal* calcium levels. Vasospasm, itself, is believed to result from the presence of RBC breakdown products in the subarachnoid space. The presence of thick clots on CT scan does correlate with the severity of subsequent vasospasm. + "HHH" therapy: If vasospasm is confirmed or suspected in the presence of neurological deterioration, "triple H" therapy (hypertension, hemodilution, and hypervolemia) may be instituted. Although a recent Cochrane review concluded that there is no convincing evidence supporting it, triple-H therapy is commonly used in practice. [Edlow JA, Malek AM, Ogilvy CS. Aneurysmal subarachnoid hemorrhage: update for emergency physicians. The Journal of emergency medicine 2008;34:237-51.] þ Rx for SAH - Nimodipine(R) relieves spasm but doesn't relieve pain from SAH. - 60mg PO every 6 hours. Reduces spasm that results in re-bleeding. Improves outcome. þ NSA SAH recommendations on BP control in SAH: þ MRI for Subarachnoid Hemorrhage - not as good as CT. References: þ LP for subarachnoid hemorrhage Two other useful, albeit imperfect, methods to distinguish traumatic taps from true bleeds are the “3- tube” test and measuring the opening pressure of the CSF (98). In the former, one looks for diminishing numbers of RBCs from the first to the last tube trending toward zero. This last detail is crucial. Older literature shows that a “decrease” (undefined) does not discriminate between traumatic tap and true SAH (120). In a more recent study using an arbitrary cutoff of a 25% reduction from tube 1 to 4, 2 of 8 patients had aneurysms (121). Thus, a simple decrease is insufficient to exclude SAH and the last tube RBC count should approach zero. When bloody fluid is identified, wasting 2–3 mL of CSF to increase the gap between the first and last tubes improves the odds that the last tube RBC count will approach zero (98). There is no specific number of RBCs that serves as a threshold amount and the rate of RBC clearance is variable.