An Observational Study of 2,248 Patients Presenting With Headache, Suggestive of Subarachnoid Hemorrhage, Who Received Lumbar Punctures Following Normal Computed Tomography of the Head

Abstract

Objectives: The objective was to determine the incidence of subarachnoid hemorrhage (SAH) diagnosed by lumbar puncture (LP) when the head computed tomography (CT) was reported as demonstrating no subarachnoid blood.Methods: Data were obtained on patients who received LP to diagnose or exclude SAH attending six hospitals over 5 years. Subsequent investigations and outcomes were reviewed in all patients with LPs that did not exclude SAH.Results: A total of 2,248 patients were included. A total of 1,898 LPs were suitable for biochemical analysis, of which 92 (4.8%) were positive for blood, suggesting SAH; 1,507 (79.4%) were negative; and 299 (15.6%) were inconclusive. Of the 92 patients with positive cerebrospinal fluid analysis, eight patients (0.4%) had aneurysms on further imaging, and one had a carotid cavernous fistula. Conclusions:In patients presenting to the emergency department with acute severe headache, LP to diagnose or exclude SAH after negative head CT has a very low diagnostic yield, due to low prevalence of the disease and uninterpretable or inconclusive samples. A clinical decision rule may improve diagnostic yield by selecting patients requiring further evaluation with LP following nondiagnostic or normal noncontrast CT brain imaging.ACADEMIC EMERGENCY MEDICINE 2015;22:1267-1273© 2015 by the Society for Academic Emergency Medicine A cute headache is a common presentation to the emergency department (ED), accounting for around 1% to 2% of all encounters.1,2 The differential diagnosis is wide and includes potentially life-threatening conditions, such as aneurysmal subarachnoid hemorrhage (SAH). Aneurysmal SAH has an incidence of approximately six to eight per 100,000 per person-years, and prevalence of 0.4% to 6%, estimated overall to be around 2%. 3,4 There is an overall risk of rupture of 1.9%.4 SAH has a 1-month mortality of around 40% to 45%, and of those surviving the hemorrhage, around 30% will have severe disabilities. 5,6 Following the initial presentation, the risk of rebleeding is approximately 1.5% per day and 15% to 20% in the first

Determination of a Testing Threshold for Lumbar Puncture in the Diagnosis of Subarachnoid Hemorrhage after a Negative Head Computed Tomography: A Decision Analysis

“…1 Misdiagnosis and morbidity rates associated with SAH are high, 2 and current clinical practice guidelines 3,4 recommend lumbar puncture (LP) after a negative noncontrast computed tomography (CT) despite a very low probability of disease. 5 Importance Lumbar puncture, however, is not without risks including meningitis, neurologic injury, and patient harm from further pursuit of false-positive results. [6][7][8] Attempts to balance these complex processes has made the decision of whether to perform LP following CT a decision point both with high clinician variability 2,9 and with the potential for important impact on patient outcomes.…”

Magnetic resonance imaging in a guinea pig model of inner ear decompression sickness and barotrauma

“…Computed tomography (CT) might also be of value in distinguishing IEBT from IEDS, as it has been shown to be capable of demonstrating small volumes of air in the labyrinth . Although CT has been shown to be highly accurate in identifying blood in cerebrospinal fluid following subarachnoid hemorrhage, blood would not be resolved in the labyrinth in most situations with standard techniques. MRI has been reported to be more sensitive in the identification of blood, especially in more chronic situations .…”

What is Currently the Best Investigational Approach to the Patient With Sudden‐Onset Severe Headache?

“…18 Again, if the pretest probability of bleeding is considered high, and there has been a long time since the ictus (with low sensitivity of CT as a result), then within a two-week time window, LP will essentially be able to confirm or exclude a bleeding. Response by Dr. Alstadhaug: As discussed, routine use of LP has become controversial.…”

“…Sayer and colleagues reported NN LP of 250 to reveal an additional aneurysm bleeding. 18 Again, if the pretest probability of bleeding is considered high, and there has been a long time since the ictus (with low sensitivity of CT as a result), then within a two-week time window, LP will essentially be able to confirm or exclude a bleeding. The numbers must also be seen in the light of the complications of the procedure, but also of other potential benefits of examining the cerebrospinal fluid.…”