Negative Head Computed Tomography Research Articles

Utility of cranial MRI in non-traumatic headache patients with prior negative head CT within 1 month

To investigate the importance of additional cranial magnetic resonance imaging (cMRI) in non-traumatic headache patients with a prior negative head computed tomography (CT) examination within 1 month. This retrospective study analysed 162 adult patients with non-traumatic headache who underwent cMRI within 1 month of a negative initial head CT at the emergency department (ED). The diagnostic yield and false-referral rate were analysed according to the revisit duration (early [≤1 week] versus late [>1-4 weeks] revisits), patient care settings (ED versus outpatient clinics [OPC]), and clinical variables. Subsequent patient management change (PMC), such as admission and treatment (AT) or outpatient clinic treatment (OT), were also investigated. The overall diagnostic yield of cMRI was 17.3% (28/162) and the false-referral rate was 1.2% (2/162). The diagnostic yield of cMRI was significantly different according to the patient care settings (ED, 24.7% [21/85] versus OPC, 9.1% [7/77]; p=0.02). The diagnostic yield was highest in the ED-early-revisit group (25.4% [18/71]), 45% (9/20) in those with systemic signs, and 46.7% (14/30) in those with symptom change. Among patients with positive cMRI findings, 90% (27/30) received AT and 3.3% (1/30) received OT. Among OPC-revisit-negative cMRI patients, PMC occurred in 0% (0/50). The diagnostic yield of cMRI was relatively high for headache patients who revisited the ED earlier, especially in those with systemic signs or symptom change. Most positive cMRI cases experienced PMC. Negative cMRI in OPC-revisit patients might help clarify the benign nature of a condition.

A-094 Performance Evaluation of GFAP and UCH-L1 Biomarkers for Traumatic Brain Injury in the Alinity i TBI Test (in development)

Abstract Background Traumatic Brain Injury (TBI) has been recognized as an important cause of death and disability and is a growing public health problem. An estimated 69 million people globally experience a TBI annually. Blood-based biomarkers such as glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1) have shown utility to predict acute traumatic intracranial injury on head CT scan after TBI. Methods The Alinity i TBI test is a panel of in vitro diagnostic chemiluminescent microparticle immunoassays for the measurement of GFAP and UCH-L1 in plasma and serum. Performance characteristics such as detection limits, imprecision, linearity, measuring interval, expected values, and interferences were established following CLSI guidance. A feasibility cohort of 354 subjects was used to establish cutoffs which assist in determining the need for a CT (computed tomography) scan of the head. A prospective study was conducted to assess the clinical performance of the TBI test. Fresh plasma specimens from 97 mild TBI subjects presenting to Level I trauma centers were collected within 12 h of injury from subjects ≥18 years of age who presented with suspected TBI and had a head CT scan performed. The TBI interpretation is considered positive if either GFAP or UCH-L1 is greater than or equal to the cutoffs. The TBI interpretation is considered negative if both GFAP and UCH-L1 are less than the cutoffs. Results The analytical measuring interval (AMI) extends from the limit of quantitation (LoQ) to the upper LoQ and is determined by the range that demonstrates acceptable performance for linearity, imprecision, and bias. The AMI is 6.1 to 42 000.0 pg/mL for GFAP and 26.3 to 25 000.0 pg/mL for UCH-L1. Within-laboratory imprecision (20 day) ranged from 2.8% to 5.3% CV for GFAP and 2.1% to 5.6% CV for UCH-L1. Cutoffs for GFAP and UCH-L1 of 35.0 pg/mL and 400.0 pg/mL, respectively, were selected using both 10-fold cross validation and bootstrapping methods and applying a selection criterion of negative predictive value (NPV) (prevalence adjusted) ≥99% and Sensitivity ≥96%. Of the 97 mild TBI subjects evaluated, 14 had positive head CT scan results. All 14 of the subjects with positive head CT results had a positive TBI interpretation (Sensitivity 100.0%; 95% CI:78.5%,100.0%). There were 23 subjects with a negative TBI interpretation, all 23 had a negative head CT scan result. The NPV of the test was 100% (95% CI:85.7%,100.0%). Conclusion The Alinity i TBI test shows robust analytical performance across a broad concentration range of GFAP and UCH-L1 and may serve as a valuable tool to help evaluate TBI patients across the spectrum of mild to severe injury. The established cutoffs were evaluated in a prospective cohort of mild TBI (Glasgow Coma Scale score of 13–15) subjects and demonstrated high sensitivity and NPV relative to CT scan results, supporting the utility to rule out the need for CT scan in mild TBI subjects presenting to the emergency department. FUNDING: This work is in collaboration with the US Army Medical Materiel Development Activity, US Army Medical Research and Development Command CRADA 20-1266-CRA.

Positive Head Computed Tomography Findings in the Setting of Sport Head Injuries: Can These Athletes Return-to-Play?

The literature on athletes with positive head computed tomography (HCT) findings in the setting of sport head injuries remains sparse. To report the proportions of athletes with a positive HCT and compare acute injury characteristics and recovery between those with and without a positive HCT. A retrospective, single-institution, cohort study was performed with all athletes aged 12 to 23 years seen at a regional concussion center from 11/2017 to 04/2022. The cohort was dichotomized into positive vs negative HCT (controls). Acute injury characteristics (ie, loss of consciousness and amnesia) and recovery, as measured by days to return-to-learn (RTL), symptom resolution, and return-to-play (RTP) were compared. χ 2 and Mann-Whitney U tests were performed. Of 2061 athletes, 226 (11.0%) received an HCT and 9 (4.0%) had positive findings. HCT findings included 4 (44.4%) subdural hematomas, 1 (11.1%) epidural hematoma, 2 (22.2%) facial fractures, 1 (11.1%) soft tissue contusion, and 1 (11.1%) cavernous malformation. All 9 (100.0%) athletes were treated nonoperatively and successfully returned-to-play at a median (IQR) of 73.0 (55.0-82.0) days. No differences in loss of consciousness or amnesia were seen between positive HCT group and controls. The Mann-Whitney U test showed differences in RTL (17.0 vs 4.0 days; U = 45.0, P = .016) and RTP (73.0 vs 27.0 days; U = 47.5, P = .007) but not in symptom resolution. Our subanalysis showed no differences across all recovery metrics between acute hemorrhages and controls. Among athletes seen at a regional concussion center who underwent an acute HCT, positive findings were seen in 4%. Although athletes with a positive HCT had longer RTL and RTP, symptom resolution was similar between those with a positive and negative HCT. All athletes with a positive HCT successfully returned to play. Despite a more conservative approach to athletes with a positive HCT, clinical outcomes are similar between those with and without a positive HCT.

Outcomes in Patients With Mild Traumatic Brain Injury Without Acute Intracranial Traumatic Injury

Traumatic brain injury (TBI) affects millions of people in the US each year. Most patients with TBI seen in emergency departments (EDs) have a Glasgow Coma Scale (GCS) score of 15 and a head computed tomography (CT) scan showing no acute intracranial traumatic injury (negative head CT scan), yet the short-term and long-term functional outcomes of this subset of patients remain unclear. To describe the 2-week and 6-month recovery outcomes in a cohort of patients with mild TBI with a GCS score of 15 and a negative head CT scan. This cohort study analyzed participants who were enrolled from January 1, 2014, to December 31, 2018, in the Transforming Research and Clinical Knowledge in Traumatic Brain Injury (TRACK-TBI) study, a prospective, observational cohort study of patients with TBI that was conducted in EDs of 18 level I trauma centers in urban areas. Of the total 2697 participants in the TRACK-TBI study, 991 had a GCS score of 15 and negative head CT scan and were eligible for inclusion in this analysis. Data were analyzed from September 1, 2021, to May 30, 2022. The primary outcome was the Glasgow Outcome Scale-Extended (GOS-E) score, which was stratified according to functional recovery (GOS-E score, 8) vs incomplete recovery (GOS-E score, <8), at 2 weeks and 6 months after the injury. The secondary outcome was severity of mild TBI-related symptoms assessed by the Rivermead Post Concussion Symptoms Questionnaire (RPQ) total score. A total of 991 participants (mean [SD] age, 38.5 [15.8] years; 631 male individuals [64%]) were included. Of these participants, 751 (76%) were followed up at 2 weeks after the injury: 204 (27%) had a GOS-E score of 8 (functional recovery), and 547 (73%) had a GOS-E scores less than 8 (incomplete recovery). Of 659 participants (66%) followed up at 6 months after the injury, 287 (44%) had functional recovery and 372 (56%) had incomplete recovery. Most participants with incomplete recovery reported that they had not returned to baseline or preinjury life (88% [479 of 546]; 95% CI, 85%-90%). Mean RPQ score was 16 (95% CI, 14-18; P < .001) points lower at 2 weeks (7 vs 23) and 18 (95% CI, 16-20; P < .001) points lower at 6 months (4 vs 22) in participants with a GOS-E score of 8 compared with those with a GOS-E score less than 8. This study found that most participants with a GCS score of 15 and negative head CT scan reported incomplete recovery at 2 weeks and 6 months after their injury. The findings suggest that emergency department clinicians should recommend 2-week follow-up visits for these patients to identify those with incomplete recovery and to facilitate their rehabilitation.

Is a Lumbar Puncture Required to Rule Out Atraumatic Subarachnoid Hemorrhage in Emergency Department Patients With Headache and Normal Brain Computed Tomography More Than Six Hours After Symptom Onset?

Atraumatic subarachnoid hemorrhage (SAH) is a deadly condition that most commonly presents as acute, severe headache. Controversy exists concerning evaluation of SAH based on the time from onset of symptoms, specifically if the headache occurred > 6h prior to patient presentation. Do patients undergoing evaluation for atraumatic SAH who have a negative computed tomography (CT) scan of the head obtained more than 6h after symptom onset require a subsequent lumbar puncture to rule out the diagnosis? Studies retrieved included a retrospective cohort study, two prospective cohort studies, and a case-control study. These studies provide estimates of the diagnostic accuracy of head CT imaging obtained > 6h from symptom onset and diagnostic test characteristics of subsequent lumbar puncture. The probability of SAH above which emergency clinicians should perform a lumbar puncture is 1.0%. This threshold is essentially the same as the estimated probability of SAH in patients with a negative head CT obtained more than 6h from symptom onset. Emergency physicians might reasonably decide to either perform or forego this procedure. Consequently, we contend that the decision whether to perform lumbar puncture in these instances is an excellent candidate for shared decision-making.

Admission of Pediatric Concussion Injury Patients: Is It Necessary?

BackgroundCurrently there is no consensus on the management of patients with a concussion and negative computed tomography (CT) of the head. This study examined the necessity of admitting pediatric patients with concussive symptoms. The purpose of this study was to determine if pediatric patients evaluated in the emergency department (ED) for concussion with a negative head CT scan require routine hospital admission. Materials and methodsA retrospective chart review of pediatric trauma patients admitted to the hospital for a concussion from 2010 to 2017 was conducted after IRB approval (1709005621). Only patients with a negative head CT were included. Demographic information, ED evaluation, and hospital course were reviewed. ResultsA total of 90 patients (Mage = 10 y; 72.2% male) were included in the analysis. The average Glasgow coma scale was 14.6 (range 9-15). Loss of consciousness was reported by 36.7% (n = 33) of patients. Reported symptoms included nausea/emesis in 35.5% (n = 32) and altered mental status in 40% (n = 36). Following admission, 94.4% of patients were discharged within 24 h of admission. Of the four patients (4.4%) that stayed longer than 24 h, only two hospitalizations were related to the concussion (inability to tolerate diet). One patient had a fever unrelated to the concussion and one stayed because of social issues. Average length of stay for these patients was 2.75 d (range 2-4 d). There was no difference in Glasgow coma scale in comparison to patients who were discharged within 24 h. ConclusionsAlthough there are a large number of pediatric patients evaluated in the ED for concussion injuries, very few of these patients require any further care. Our study suggests that patients with concussion and a negative head CT who tolerate a diet can be safely discharged home.

Is there a role for lumbar puncture in early detection of subarachnoid hemorrhage after negative head CT?

To investigate the role of lumbar puncture (LP) after a negative head computed tomography (CT) when ruling out subarachnoid hemorrhage (SAH) within 24h of symptom onset. In a single-center, retrospective cohort study, we studied a consecutive series of patients from 2011 to 2015. All patients underwent CT or CT following LP to rule out SAH. Patients were categorized into four groups depending on the time of symptom onset to initial head CT: 0-6h, 6-12h, 12-24h, and over 24h. Experienced radiologists interpreted all CT scans. We investigated the sensitivity, specificity, and negative predictive value (NPV) of noncontrast CT in detecting SAH. Of 539 patients with suspected SAH and negative CT, 280 (51.9%) had their CT performed within 24h of symptom onset. None of these patients had SAH. Five (1.9%) out of 259 patients with CT performed after 24h of symptom onset had SAH diagnosed, and two turned out to be aneurysmal. When CT was performed within 24h of symptom onset it had a sensitivity of 100% (95% CI 95-100%), specificity of 98% (95% CI 96-99.7%), and NPV of 100% (95% CI 98-100%) in detecting SAH. Modern CT scanners seem to have high sensitivity and specificity in the diagnosis of SAH when performed within 24h of symptom onset. Beyond this point, CT seems to lack sensitivity and further investigation with LP is required.

Acute Headache in the Emergency Department: Is Lumbar Puncture Still Necessary to Rule Out Subarachnoid Hemorrhage?

The purpose of the Research to Practice column is to review current primary journal articles that directly affect the practice of the advanced practice nurse (APN) in the emergency department. This review examines the findings of Carpenter et al. (2016) from their article, "Spontaneous Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis Describing the Diagnostic Accuracy of History, Physical Exam, Imaging, and Lumbar Puncture With an Exploration of Test Thresholds." The authors concluded that although no history or physical examination finding can be used to rule in or rule out spontaneous subarachnoid hemorrhage (SAH), the complaint of neck stiffness can increase the likelihood of SAH. In addition, the authors concluded that noncontrast head computed tomography (CT) is accurate in ruling out/in SAH when performed within 6 hr of symptom onset in adults with symptoms consistent with SAH and that the traditional gold standard of confirmatory lumbar puncture after a negative head CT scan is only helpful in patients with a very high pretest probability of SAH. By applying the evidence-based criteria presented in this study, the emergency department APN can confidently rule out SAH and reduce patient risks from unnecessary invasive and costly testing.

Head injuries and the risk of concurrent cervical spine fractures.

Cervical spine injuries of variable severity are common among patients with an acute traumatic brain injury (TBI). We hypothesised that TBI patients with positive head computed tomography (CT) scans would have a significantly higher risk of having an associated cervical spine fracture compared to patients with negative head CT scans. This widely generalisable retrospective sample was derived from 3,023 consecutive patients, who, due to an acute head injury (HI), underwent head CT at the Emergency Department of Tampere University Hospital (August 2010-July 2012). Medical records were reviewed to identify the individuals whose cervical spine was CT-imaged within 1week after primary head CT due to a clinical suspicion of a cervical spine injury (CSI) (n = 1,091). Of the whole cranio-cervically CT-imaged sample (n = 1,091), 24.7% (n = 269) had an acute CT-positive TBI. Car accidents 22.4% (n = 244) and falls 47.8% (n = 521) were the most frequent injury mechanisms. On cervical CT, any type of fracture was found in 6.6% (n = 72) and dislocation and/or subluxation in 2.8% (n = 31) of the patients. The patients with acute traumatic intracranial lesions had significantly (p = 0.04; OR = 1.689) more cervical spine fractures (9.3%, n = 25) compared to head CT-negative patients (5.7%, n = 47). On an individual cervical column level, head CT positivity was especially related to C6 fractures (p = 0.031, OR = 2.769). Patients with cervical spine fractures (n = 72) had altogether 101 fractured vertebrae, which were most often C2 (22.8, n = 23), C7 (19.8%, n = 20) and C6 (16.8%, n = 17). Head trauma patients with acute intracranial lesions on CT have a higher risk for cervical spine fractures in comparison to patients with a CT-negative head injury. Although statistically significant, the difference in fracture rate was small. However, based on these results, we suggest that cervical spine fractures should be acknowledged when treating CT-positive TBIs.

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

The objective was to determine the testing threshold for lumbar puncture (LP) in the evaluation of aneurysmal subarachnoid hemorrhage (SAH) after a negative head computed tomography (CT). As a secondary aim we sought to identify clinical variables that have the greatest impact on this threshold. A decision analytic model was developed to estimate the testing threshold for patients with normal neurologic findings, being evaluated for SAH, after a negative CT of the head. The testing threshold was calculated as the pretest probability of disease where the two strategies (LP or no LP) are balanced in terms of quality-adjusted life-years. Two-way and probabilistic sensitivity analyses (PSAs) were performed. For the base-case scenario the testing threshold for performing an LP after negative head CT was 4.3%. Results for the two-way sensitivity analyses demonstrated that the test threshold ranged from 1.9% to 15.6%, dominated by the uncertainty in the probability of death from initial missed SAH. In the PSA the mean testing threshold was 4.3% (95% confidence interval = 1.4% to 9.3%). Other significant variables in the model included probability of aneurysmal versus nonaneurysmal SAH after negative head CT, probability of long-term morbidity from initial missed SAH, and probability of renal failure from contrast-induced nephropathy. Our decision analysis results suggest a testing threshold for LP after negative CT to be approximately 4.3%, with a range of 1.4% to 9.3% on robust PSA. In light of these data, and considering the low probability of aneurysmal SAH after a negative CT, classical teaching and current guidelines addressing testing for SAH should be revisited.

Controversies in the Diagnosis of Subarachnoid Hemorrhage

BackgroundHeadache is a common chief complaint in emergency departments, accounting for 2% of visits, and subarachnoid hemorrhage (SAH) is a life-threating cause of headache. This deadly disease is most commonly due to aneurysmal rupture. Various approaches exist for diagnosis, with recent studies evaluating these approaches. A great deal of controversy exists about the optimal diagnosis strategy for SAH. ObjectiveThis article in the Best Clinical Practice Series seeks to educate emergency physicians on the recent literature in the diagnosis of SAH and provide an evidence-based approach. DiscussionVarious diagnostic strategies exist, including use of noncontrast head computed tomography (CT) alone, CT/lumbar puncture (LP) in combination, CT/CT angiography, and magnetic resonance imaging/magnetic resonance angiography. The use of clinical decision rules has also been espoused, and several contemporary studies have evaluated cerebrospinal fluid results of red blood cell count and xanthochromia in the diagnosis of SAH. Recent literature supports that a negative head CT done within 6 h of headache onset places the patient at a < 1% risk for SAH. With the complex literature, a shared decision-making model should be followed with options, risks, and benefits discussed with the patient. ConclusionsLiterature support exists for all of the diagnostic strategies. The American College of Emergency Physicians Clinical Policy supports CT and LP for definitive diagnosis. Risk stratification and a shared decision-making model with the patient should be followed, and a negative head CT within 6 h of headache onset places patient at a risk of < 1% for having SAH.

Hot Off the Press: An Observational Study of 2,248 Patients Presenting with Headache, Suggestive of Subarachnoid Hemorrhage, That Received a Lumbar Puncture Following a Normal Computed Tomography of the Head.

Headache is a very common emergency department (ED) chief complaint, representing about 2.8% of all visits in the United States.1 Sudden-onset, severe headache often warrants evaluation for etiologies with unacceptably high morbidity and lethality, including subarachnoid hemorrhage (SAH). Noncontrast head computed tomography (CT) as soon as possible after the onset of headache is the initial SAH diagnostic test of choice, but older studies indicate that up to one in three SAH patients were misdiagnosed during the initial ED encounter with subsequent treatment delays producing less optimal patient outcomes due to failure to perform or appropriately interpret lumbar puncture (LP) results in headache patients with a nondiagnostic CT.2 Early-generation CT studies reported inadequate sensitivities for the diagnosis of SAH so postimaging LP was the standard workup to adequately exclude SAH.3 The American College of Emergency Physicians (ACEP) Clinical Policy Statement for the evaluation of adult headache patients currently provide a Level B recommendation supporting LP following nondiagnostic noncontrast head CT to rule out SAH.4 Recent studies using newer-generation CT scanners demonstrate significantly improved sensitivities for detecting SAH if performed within 6 hours, rendering providers and clinical educators to question the benefit for LP in this population.5 This retrospective study evaluated the diagnostic yield of LP after a nondiagnostic head CT in patients presenting to one of six urban EDs in the United Kingdom. The primary outcome was the rate of diagnosis of SAH by LP after negative head CT. Over the course of 5 years, 2,248 patients were included, of whom 92 patients had a “positive” LP, according to spectrophotometric criteria established by the authors. Several limitations of this study were noted. First, the criteria for a positive LP in this study relied on spectrophotometric cerebrospinal fluid (CSF) analysis, which is not available or routinely performed in 97% of North American EDs.5 In fact, spectrophotometric assessment of xanthochromia has specificities as low as 29% and could actually increase further CT angiography and other more invasive downstream testing.6 Additionally, patients with inconclusive CSF results did not undergo uniform evaluation, since only two of six sites evaluated equivocal LPs and most these equivocal cases were not referred for additional definitive imaging. Using different thresholds to fully evaluate equivocal cases represents differential verification bias (double gold standard bias), which falsely elevates observed estimates of sensitivity and decreases estimates of specificity.7 In addition, the authors do not report any details about the delay between the onset of the headache and CT imaging or LP, which are both important because CT loses sensitivity after 6 hours and CSF bilirubin requires several hours to manifest following a sentinel bleed.5, 8 Finally, the investigators do not assess for potential temporal bias resulting from improvements in CT imaging quality and interpretation between 2006 and 2011.9 Among 2,248 patients with an initial high-resolution (16- to 64-slice) cranial CT, 92 patients had a positive LP of whom nine (0.04%) had an aneurysm subsequently identified. A significant proportion of LPs had inconclusive or uninterpretable results, 13 and 16%, respectively. The number of LPs needed to identify one aneurysm was 250 (1/0.004). This retrospective study of acute, nontraumatic adult headache patients with suspected SAH contradicts the ACEP Clinical Policy Statement and classical teaching that providers must evaluate CSF for xanthochromia or significant red blood cells following a negative noncontrast cranial CT to rule out SAH in acute headache patients. Routine LP following nondiagnostic cranial CT in patients with acute, nontraumatic headache yields more inconclusive and false-positive results than cases of SAH when evaluating for cerebral aneurysm-related sentinel bleeds. The number needed to LP to find one case of SAH in this scenario is 250, which should motivate shared decision-making with patients and more formal assessments of quantitative test–treatment thresholds in an era of increasingly sensitive CT imaging.

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.

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. 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. 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. 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.

264 Application of the Canadian Computed Tomography Head Rule to a Very Low Risk Minor Head Injury Population

264 Application of the Canadian Computed Tomography Head Rule to a Very Low Risk Minor Head Injury Population

You Cannot Go Home: Routine Concussion Evaluation is not Enough

Traditional care of mild traumatic brain injury (MTBI) is to discharge patients from the emergency department (ED) if they have a Glasgow Coma Score (GCS) of 15 and a normal head computed tomography (CT) scan. However, this does not address short-term neurocognitive deficits. Our hypothesis is that a notable percentage of patients will need outpatient neurocognitive therapy despite a reassuring initial presentation. This is a retrospective review of patients with MTBI at an urban Level I trauma center. Inclusion criteria were a diagnosis of MTBI in patients 14 years old or older, GCS 15, negative head CT scan, a completed neurocognitive evaluation, blunt mechanism, and no confounding psychiatric comorbidities. Six thousand thirty-two patients were admitted over 18 months. Three hundred ninety-five patients met inclusion criteria. Average age was 38 years (range, 14 to 93 years), 64 per cent were male, and mean Injury Severity Score (ISS) was 8.1. Forty-one per cent were cleared for discharge without follow-up. Twenty-seven per cent required ongoing neurocognitive therapy. Three per cent were deemed unsafe for discharge home. Of the patients cleared for discharge, 88 per cent had positive/questionable loss of consciousness (LOC), whereas 81 per cent who required additional therapy had positive/questionable LOC (P = 0.20). Age, gender, ISS, and alcohol use were compared between the groups and not found to be statistically different rendering them poor predictors for appropriate discharge from the ED. A surprisingly high percentage (27%) of patients who would have met traditional ED discharge criteria were found to have persistent deficits after neurocognitive testing and were referred for ongoing therapy. We provide evidence to suggest that we should take pause before discharging patients with MTBI without a cognitive evaluation.

Ruptured aneurysmal subarachnoid hemorrhage in the emergency department: Clinical outcome of patients having a lumbar puncture for red blood cell count, visual and spectrophotometric xanthochromia after a negative computed tomography

ObjectivesOver the last decade, computed tomography scanners have gained resolution and have become the standard of care in the investigation of neurologically intact patients suffering from acute headache. The added value of the combined assessment of red blood cells count, visual and spectrophotometric xanthochromia, to detect ruptured aneurysmal subarachnoid hemorrhage (ASAH) following a negative head computed tomography (NHCT) was studied. MethodsThe population consisted of all patients who had cerebrospinal fluid tested for spectrophotometric xanthochromia between 2003 and 2009 identified through the clinical-laboratory database and who met all the inclusion criteria: >14years old, had an initial Glasgow Coma Score of 15, a non-traumatic acute headache with a suspected subarachnoid hemorrhage recorded in the initial ED differential diagnosis and an initial negative head CT scan. ResultsA total of 706 patients were included. LP identified 5 ASAH (prevalence: 0.7%). In these patients, LP parameters were as follows: high red blood cell count (from 1310 to 63,000×106/L), positive visual xanthochromia in 4 out of 5 ASAH, and positive spectrophotometric xanthochromia in 5 out of 5 ASAH. All ASAH patients were neurologically intact after intervention. No deaths or missed ASAH were reported. Angiographies were performed on 127 patients (19.5%) of which 47 (34.1%) had positive xanthochromia (visual or spectrophotometric). ConclusionsConsidering the low prevalence of ASAH following an NHCT, intense resources were utilized to identify all 5 ASAH. Lumbar puncture analyses combining red blood cell count, visual and spectrophotometric xanthochromia identified all ASAH, allowing intervention and a positive clinical outcome. Our data support 1) that LP identifies the presence of a ruptured ASAH after an NHCT and 2)` that a guide to define a subpopulation of patients who would benefit from a lumbar puncture after an NHCT would be desirable.

Eye tracking detects disconjugate eye movements associated with structural traumatic brain injury and concussion.

Disconjugate eye movements have been associated with traumatic brain injury since ancient times. Ocular motility dysfunction may be present in up to 90% of patients with concussion or blast injury. We developed an algorithm for eye tracking in which the Cartesian coordinates of the right and left pupils are tracked over 200 sec and compared to each other as a subject watches a short film clip moving inside an aperture on a computer screen. We prospectively eye tracked 64 normal healthy noninjured control subjects and compared findings to 75 trauma subjects with either a positive head computed tomography (CT) scan (n=13), negative head CT (n=39), or nonhead injury (n=23) to determine whether eye tracking would reveal the disconjugate gaze associated with both structural brain injury and concussion. Tracking metrics were then correlated to the clinical concussion measure Sport Concussion Assessment Tool 3 (SCAT3) in trauma patients. Five out of five measures of horizontal disconjugacy were increased in positive and negative head CT patients relative to noninjured control subjects. Only one of five vertical disconjugacy measures was significantly increased in brain-injured patients relative to controls. Linear regression analysis of all 75 trauma patients demonstrated that three metrics for horizontal disconjugacy negatively correlated with SCAT3 symptom severity score and positively correlated with total Standardized Assessment of Concussion score. Abnormal eye-tracking metrics improved over time toward baseline in brain-injured subjects observed in follow-up. Eye tracking may help quantify the severity of ocular motility disruption associated with concussion and structural brain injury.

Necessity of monitoring after negative head CT in acute head injury

ObjectiveThe main objective of this study was to evaluate the incidence of delayed complications in acute head injury (HI) patients with an initial normal head computed tomography (CT). Materials and methodsThis retrospective study included 3023 consecutive patients who underwent head CT due to an acute HI at the Emergency Department (ED) of Tampere University Hospital (August 2010–July 2012). Regardless of clinical injury severity, the patients with a normal head CT were selected (n=2444, 80.9%). The medical records of these patients were reviewed to identify the individuals with a serious clinically significant complication related to the primary HI. The time window considered was the following 72h after the primary head CT. A repeated head CT in the hospital ward, death, or return to the ED were indicative of a possible complication. ResultsThe majority (n=1811, 74.1%) of the patients with a negative head CT were discharged home and 1.1% (n=27) of these patients returned to ED within 72h post-CT. A repeated head CT was performed on 12 (44.4%) of the returned patients and none of the scans revealed an acute lesion. Of the 632 (25.9%) CT-negative patients admitted to the hospital ward from the ED, a head CT was repeated in 46 (7.3%) patients within 72h as part of routine practice. In the repeated CT sample, only one (0.2%) patient had a traumatic intracranial lesion. This lesion did not need neurosurgical intervention. The overall complication rate was 0.04%. ConclusionIn the present study, which includes head injuries of all severity, the probability of delayed life-threatening complications was negligible when the primary CT scan revealed no acute traumatic lesions.

Cerebral oxygen saturation monitoring in pediatric altered mental status patients

ObjectivesA pilot study assessing the potential utility of cerebral oximetry (local cerebral oxygen saturation [rcSO2]) in children presenting to the emergency department (ED) with altered mental status (AMS) and no history of trauma. MethodsPatients who presented to a tertiary pediatric ED with AMS were monitored with left and right cerebral near-infrared spectroscopy probes and the first 30 minutes of rcSO2 data was analyzed. Patients with a history of trauma were excluded. Patients with an abnormal head computed tomography (CT) (n = 146) were compared with those with a negative head CT (n = 45). ResultsMean rcSO2 values were consistent during each time period studied (5, 10, 20, and 30 minutes). In this study population, rcSO2 less than 50% or greater than 80% and increased absolute difference between the left and right rcSO2 measurements were associated with an abnormal CT scan. A difference of 12.2% between the left and right rcSO2 values had a 100% positive predictive value for an abnormal head CT among our patients. Cumulative graphical plots of rcSO2 trends showed that values <50% were associated with subdural hematomas (SDH) and values >80% were associated with epidural hematomas (EDH). ConclusionsThis study demonstrated that cerebral oximetry can noninvasively detect altered cerebral physiology among a selected patient population. The difference between the left and right rcSO2 readings most reliably identified those subjects with altered cerebral physiology. In the future, rcSO2 monitoring has the potential to be used as a screening tool to identify, localize, and characterize intracranial injuries among children with AMS without a history of trauma.

Every Peddler Praises His Own Needle: Have Clinical Rules in the Diagnosis of Subarachnoid Hemorrhage Supplanted Lumbar Punctures Yet?

1The authors state, “Research conducted among ED [emergency department] patients with possible acute coronary syndrome suggests that patients often have much higher risk thresholds for themselves than do the treating physicians.”1 AAssuming both patients and physicians are making rational decisions, list some reasons why they may have different risk thresholds. Do you think that emergency physicians have higher or lower risk thresholds than other physicians (eg, internists, pediatricians, neurosurgeons)? Why might this be so? Should our health care system try to align patient and physician acceptable risk thresholds? If so, how might this be achieved?BAssume 1) the 97% sensitivity reported for the Mark et al decision rule is externally validated and 2) the incidence of subarachnoid hemorrhage in patients presenting to the ED with acute headache is 2% and an emergency physician treats 3,500 patients per year. On average, how many years would an emergency physician have to apply this clinical rule to miss 1 subarachnoid hemorrhage? Do these sound like reasonable numbers to you? Why or why not?CNoncontrast computed tomography (CT) of the brain and lumbar punctures have associated complications. Summarize the reported frequency of complications associated with CT and lumbar puncture. Using the same data listed in question 1B, calculate how often these complications might occur. Does it matter that lumbar puncture–associated complications typically occur acutely, whereas noncontrast CT radiation exposure is associated with late-occurring morbidity and mortality? How might patient age factor into the likelihood of complications associated with CT and lumbar puncture?DIf this clinical rule were widely adopted, in 5 years would you expect that more or fewer patients would be investigated for subarachnoid hemorrhage (the use of similar decision aids in pulmonary embolism may serve as a useful example)?2The authors performed a matched control study. AUnder what circumstances are case-control studies ideal? Consider the time course of exposure and disease, the nature of the exposure and outcomes, and the frequency of the disease.BDiscuss the importance of matching in case-control studies. Why does one match? What should one match on? What should one not match on?CWhy did the authors choose 3 controls for each case? Why not 1? Why not 6?DWhat are the biases of case-control studies in general? In this study specifically?3The authors state, “Approximately 80% of subarachnoid hemorrhage cases are due to ruptured cerebral aneurysms.”1 AWhat are other common causes of nontraumatic subarachnoid hemorrhage?BIn general terms, describe the sensitivity of a noncontrast head CT in detecting these other causes. When choosing a screening test, is it preferable to be highly sensitive or highly specific? What test characteristic (ie, sensitivity, specificity) is desired for a confirmatory study?CAfter a patient complaint about a post–lumbar puncture headache, a hospital administrator proposes that the ED replace lumbar puncture with CT angiography when attempting to exclude subarachnoid hemorrhage in patients with a negative initial head CT result. What do you think about this, assuming the combination of CT and CT angiography is 99% sensitive for diagnosing a subarachnoid hemorrhage, as recently reported?24The authors performed a sensitivity analysis to assess the rule's stability, using a 1,000-iteration bootstrap analysis. AWhat is a sensitivity analysis? Why are sensitivity analyses often performed in observational studies?BWhat is a bootstrap analysis? Why are bootstrap analyses especially important when evaluating clinical decision rule performance? What assumptions are invoked by bootstrap analyses?