Differentiation between traumatic tap and aneurysmal subarachnoid hemorrhage: prospective cohort study

Abstract

Objectives To describe the findings in cerebrospinal fluid from patients with acute headache that could distinguish subarachnoid hemorrhage from the effects of a traumatic lumbar puncture. Design A substudy of a prospective multicenter cohort study. Setting 12 Canadian academic emergency departments, from November 2000 to December 2009. Participants Alert patients aged over 15 with an acute non-traumatic headache who underwent lumbar puncture to rule out subarachnoid hemorrhage. Main outcome measure Aneurysmal subarachnoid hemorrhage requiring intervention or resulting in death. Results Of the 1739 patients enrolled, 641 (36.9%) had abnormal results on cerebrospinal fluid analysis with >1×10 6 /L red blood cells in the final tube of cerebrospinal fluid and/or xanthochromia in one or more tubes. There were 15 (0.9%) patients with aneurysmal subarachnoid hemorrhage based on abnormal results of a lumbar puncture. The presence of fewer than 2000×10 6 /L red blood cells in addition to no xanthochromia excluded the diagnosis of aneurysmal subarachnoid hemorrhage, with a sensitivity of 100% (95% confidence interval 74.7% to 100%) and specificity of 91.2% (88.6% to 93.3%). Conclusion No xanthochromia and red blood cell count <2000×10 6 /L reasonably excludes the diagnosis of aneurysmal subarachnoid hemorrhage. Most patients with acute headache who meet this cut off will need no further investigations and aneurysmal subarachnoid hemorrhage can be excluded as a cause of their headache.

Determining the Value of Cerebrospinal Fluid Lactate Dehydrogenase Level in Differentiating Subarachnoid Hemorrhage From Traumatic Lumbar Puncture

“…Perry et al 9 enrolled 1739 awake patients older than 15 years who had severe headaches. They concluded that a sensitive cutoff point for RBC counts in SAH was more than 2000 310 6 /L.…”

Validation of cerebrospinal fluid findings in aneurysmal subarachnoid hemorrhage

“…Thus, for practical purposes, we assumed that the lowest RBC count represented the last tube collected in all cases, consistent with the definition used in the derivation study of interest [11].…”

“…Recently, data from the largest prospective study examining diagnostic testing for SAH revealed that, among 1739 patients undergoing LP, the presence of either a CSF RBC count 2000 × 10 6 /L or more or visible xanthochromia identified 15 patients with aSAH with 100% sensitivity (95% confidence interval [CI], 74.7-100.0) [11]. Given this potentially promising approach, we sought to provide a narrower CI for sensitivity by applying these CSF analysis criteria to a 13-year case series of patients diagnosed with aSAH after LP.…”

“…Unfortunately false-positive LPs because of elevated RBC counts are common, most often attributed to traumatic technique ("traumatic taps," with reported rates up to 30%) [9][10][11]. Resultant workups can result in unnecessary and potentially harmful diagnostic testing; rates of neurologic complications after cerebral digital subtraction angiography (DSA) have been reported as high as 1.3% [12].…”

“…Although often suggestive, analyses using the percentage decrease in RBCs between sequential tubes have failed to produce a clearly accepted cutoff value [9][10][11]15]. This is largely because CSF collection volumes are not standardized, and also because traumatic taps and SAH are not mutually exclusive conditions.…”