Acute Obstructive Hydrocephalus: An Unexpected Cause of Cardiac Arrest

BACKGROUND

Emergency physicians are well-versed in managing cardiac arrests, including the diagnostic and therapeutic steps after return of spontaneous circulation. Neurologic emergencies are a common cause of out-of-hospital cardiac arrest and must remain high in the differential diagnosis, as such cases often require specific interventions that may deviate from more common care pathways. Performing a noncontrast head computed tomography (NCHCT) scan after cardiac arrest has been found to change management, although the optimal timing of this imaging is unclear.

CASE REPORT

This is the case of a young, pregnant woman who presented to the emergency department after cardiac arrest with return of spontaneous circulation in the prehospital setting. She was found to have acute obstructive hydrocephalus on NCHCT, which was later confirmed to be due to a previously undiagnosed colloid cyst of the third ventricle. This acute obstruction resulted in myocardial stunning and, ultimately, cardiac arrest. Although outcomes are often dismal when the cause of arrest is secondary to neurologic catastrophe, this patient survived with completely intact neurologic function. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although acute obstructive hydrocephalus due to a colloid cyst adjacent to the third ventricle is a rare condition, it is a potentially reversible neurologic cause of out-of-hospital cardiac arrest. However, positive outcomes depend on obtaining the diagnosis rapidly with neurologic imaging and advocating for neurosurgical intervention. This case supports the recommendation that emergency physicians should strongly consider post-cardiac arrest neurologic imaging when another cause is not immediately obvious.

Comparing blood biomarkers to clinical decision rules to select patients suspected of traumatic brain injury for head computed tomography

INTRODUCTION

Traumatic brain injury (TBI) is a major public health concern in the U.S. Recommendations for patients admitted in the emergency department (ED) to receive head computed tomography (CT) scan are currently guided by various clinical decision rules.

OBJECTIVE

To compare how a blood biomarker approach compares with clinical decision rules in terms of predicting a positive head CT in adult patients suspected of TBI.

METHODS

We retrospectively identified patients transported to our emergency department and underwent a noncontrast head CT due to suspicion of TBI and who had blood samples available. Published thresholds for serum and plasma glial fibrillary acidic protein (GFAP), ubiquitin carboxyl-terminal hydrolase-L1 (UCH-L1), and serum S100β were used to make CT recommendations. These blood biomarker-based recommendations were compared to those achieved under widely used clinical head CT decision rules (Canadian, New Orleans, NEXUS II, and ACEP Clinical Policy).

RESULTS

Our study included 463 patients, of which 122 (26.3%) had one or more abnormalities presenting on head CT. Individual blood biomarkers achieved high negative predictive value (NPV) for abnormal head CT findings (88%-98%), although positive predictive value (PPV) was consistently low (25%-42%). A composite biomarker-based decision rule (GFAP+UCH-L1)'s NPV of 100% and PPV of 29% were comparable or better than those achieved under the clinical decision rules.

CONCLUSION

Blood biomarkers perform at least as well as clinical rules in terms of selecting TBI patients for head CT and may be easier to implement in the clinical setting. A prospective study is necessary to validate this approach.

Physical findings of crowned dens syndrome

If meningitis is suspected, head computed tomography is performed before cerebrospinal fluid collection. Crown dens syndrome can be diagnosed using simultaneous CT scans of the head and neck. Thus, unnecessary CSF tap test can be avoided.

Iterative Reconstruction in Dose Reduction of A Head CT Examination and Corresponding Acquisition Parameter Selection

PURPOSE

To investigate the potential of iterative reconstruction in radiation dose reduction during head computed tomography (CT) examinations and to evaluate the relationship between the parameters milliampere second (mAs), kilovoltage (kV), and iterative reconstruction strength using a live ovine (sheep) model.

METHODS

A sheep was scanned on a SOMATOM Force (Siemens Healthineers) CT scanner at 12 mAs and 3 kV. Images were reconstructed with filtered back projection (FBP) and the Advanced Modeled Iterative Reconstruction (ADMIRE; Siemens Healthineers) strengths 1 to 5. Images with 216 combinations of varying doses, kVs, and reconstructions were rated by 2 neuroradiologists for low-contrast detectability (ie, gray-white matter differentiation) and image texture.

RESULTS

Using only gray-white matter differentiation, maximum dose reduction was 75% at 100 kV with ADMIRE-3, and using only image texture, maximum dose reduction was 75% at 120 kV (and 140 kV) with ADMIRE-5. When these 2 metrics were combined, maximum dose reduction was 50% at 120 kV with ADMIRE-3. Other kV levels and higher iterative reconstruction strengths did not offer superior results.

DISCUSSION

Although artificial intelligence algorithms are certainly gaining momentum, iterative reconstruction technology likely will remain more accessible to most hospitals and imaging centers. Dose reduction with preservation of image quality (ie, gray-white differentiation and image texture) can be achieved when complemented by appropriate iterative reconstruction strength. However, the effect of iterative reconstruction strength on gray-white differentiation and image texture does not necessarily converge on the same pattern.

CONCLUSION

Maximum dose reduction was 50% at 120 kV with ADMIRE-3, which confirms the potential for dose reduction with appropriately chosen iterative reconstruction strength and reveals a preference for 120 kV, as well as a limit to dose reduction by further increasing iterative reconstruction strength. A better understanding of dose-voltage-reconstruction relationships in iterative reconstruction might allow for greater dose reductions than current practices allow.

Development of an automatic multiplanar reconstruction processing method for head computed tomography

BACKGROUND

Head computed tomography (CT) is a commonly used imaging modality in radiology facilities. Since multiplanar reconstruction (MPR) processing can produce different results depending on the medical staff in charge, there is a possibility that the antemortem and postmortem images of the same person could be assessed and identified differently.

OBJECTIVE

To propose and test a new automatic MPR method in order to address and overcome this limitation.

METHODS

Head CT images of 108 cases are used. We employ the standardized transformation of statistical parametric mapping 8. The affine transformation parameters are obtained by standardizing the captured CT images. Automatic MPR processing is performed by using this parameter. The sphenoidal sinus of the orbitomeatal cross section of the automatic MPR processing of this study and the conventional manual MPR processing are cropped with a matrix size of 128×128, and the value of zero mean normalized correlation coefficient is calculated.

RESULTS

The computed zero mean normalized cross-correlation coefficient (Rzncc) of≥0.9, 0.8≤Rzncc < 0.9 and 0.7≤Rzncc < 0.8 are achieved in 105 cases (97.2%), 2 cases (1.9%), and 1 case (0.9%), respectively. The average Rzncc was 0.96±0.03.

CONCLUSION

Using the proposed new method in this study, MPR processing with guaranteed accuracy is efficiently achieved.

Simulation on system configuration for stationary head CT using linear carbon nanotube x-ray source arrays

Purpose: The invention of carbon nanotube (CNT) x-ray source arrays has enabled the development of novel imaging systems, including stationary tomosynthesis and stationary computed tomography (CT) with fast data acquisition, mechanically robust structures, and reduced image blur from source-detector motion. In this work, we report the results of simulation studies of potential system configurations for a stationary head CT (s-HCT) using linear CNT x-ray sources and detector arrays. Approach: We explored s-HCT configurations that utilize one, two, and three linear CNT source arrays. Simulations were implemented using three digital phantoms with both CPU and GPU computing. Sinogram coverage was used for qualitative evaluation of the CT projection collection efficiency for each configuration. A modified low-contrast Shepp-Logan (SL) phantom was implemented for image quality assessment using quantitative metrics. Different iterative reconstruction (IR) methods were compared with both qualitative and quantitative assessments. Results: Sinogram coverage of s-HCT configurations was sensitive to the number of CNT source arrays and geometry. The simulations suggest that a s-HCT configuration with three planes gives near complete sinogram coverage. Such a configuration enables accurate reconstruction of the low-contrast SL phantom and considerably diminished artifacts caused by the system geometry. Conclusions: An optimized s-HCT system configuration with three linear CNT x-ray source arrays is feasible. IR algorithms can diminish artifacts caused by sparse and asymmetrical scans. The proposed s-HCT system configuration is currently under construction.

Rapid Detection of Significant Traumatic Brain Injury Requiring Emergency Intervention

Moderate and severe traumatic brain injuries (TBI) are a major cause of severe morbidity and mortality; rapid diagnosis and management allow secondary injury to be minimized. Traumatic brain injury is only one of many potential causes of altered mental status; head computed tomography (HCT) is used to definitively diagnose TBI. Despite its widespread use and obvious importance, interpretation of HCT images is rarely covered by formal didactics during general surgery or even acute care surgery training. The schema illustrated here may be applied in a rapid and reliable fashion to HCT images, expediting the diagnosis of clinically significant traumatic brain injury that warrants emergent medical and surgical therapies to reduce intracranial pressure. It consists of 7 normal anatomic structures (cerebrospinal fluid around the brain stem, open fourth ventricle, "baby's butt," "Mickey Mouse ears," absence of midline shift, sulci and gyri, and gray-white differentiation). These 7 features can be seen even as the CT scanner obtains images, allowing the trauma team to expedite medical management of intracranial hypertension and pursue neurosurgical consultation prior to radiologic interpretation if the features are abnormal.

Utility of Abnormal Head Computed Tomography in Predicting Outcome in Out-of-Hospital Cardiac Arrest Victims

Head computed tomography (HCT) is often performed postcardiac arrest to assess for hypoxic-ischemic brain injury. Our primary objective was to assess whether cerebral edema (CE) on early HCT is associated with poor survival and neurologic outcome after out-of-hospital cardiac arrest (OHCA).We included subjects from a prospectively collected database of OHCA adults who received targeted temperature management at two hospitals from July 2009 to July 2018. We included cases if an emergency department (ED) HCT was performed. Patient demographics and cardiac arrest variables were collected. HCT results were abstracted from radiology reports. HCT findings were categorized as no acute disease, evidence of CE, or excluded (bleed, tumor, and stroke). Outcomes were survival to discharge or dichotomized discharge cerebral performance category (CPC) of 1-2 (good neurologic outcome) versus 3-5 (poor neurologic outcome). Univariate and multivariate analyses were performed. There were 425 OHCA, of which 315 had ED HCT with 277 cases included. Patients were predominately male (65.0%), average age of 60.9 years and average body mass index of 30.5. Of all cases, 44 (15.9%) showed CE on computed tomography. Univariate analysis demonstrated that CE was associated with 9.2-fold greater odds of poor outcome (odds ratio [OR]: 9.23; 95% confidence interval [CI] 1.73-49.2) and 9.1-fold greater odds of death (OR: 9.09, 95% CI 2.4-33.9). In adjusted analysis, CE was associated with a poor CPC outcome (adjusted odds ratios [AOR]: 14.9, 95% CI 2.49-88.4), and death (AOR: 13.7, 95% CI 3.26-57.4). Adjusted survival analysis demonstrated that patients with CE on HCT had 3.6-fold greater hazard of death than those without CE (hazard ratios 3.56, 95% CI 2.34-5.41). The results identify that CE on HCTs early in the postarrest period in OHCA patients is strongly associated with poor rates of survival and neurologic outcome. Prospective work is needed to further define the role of early HCT in postarrest neuroprognostication.

Clinical Characteristics Predict the Yield of Head Computed Tomography Scans among Intoxicated Trauma Patients: Implications for the Initial Work-up

Background and Aims:

Alcohol intoxication may confound the clinical assessment of the trauma patient. Head computed tomography (h-CT) is the standard imaging technique to rule out intracranial injury in most intoxicated trauma patients. The objective of this study was to determine whether certain clinical findings (computed clinical score [CCS]) could predict the h-CT yield, admission, and neurosurgical consultation (NSC) among intoxicated trauma patients.

Materials and Methods:

This is a 4-year retrospective cohort study (2013–2017) of trauma patients who presented to our level 1 trauma center emergency department with alcohol intoxication. For each patient, a computed clinical score (CCS) was generated based on the following findings: age ≥50 years, Glasgow Coma Scale <13, evidence of trauma above the clavicles, amnesia, loss of consciousness, headache, vomiting, and seizures. The primary endpoints were NSC, admission, and acute h-CT finding. Univariate and multivariate regressions were used to compare predictors of the primary endpoints.

Results:

We identified 437 intoxicated trauma patients (median age: 35 years [interquartile range: 25–50]; 71.9% men; median blood alcohol content: 207.8 mg/dL). One hundred and twenty-four (30.4%) patients had acute findings on h-CT, 351 (80.3%) were admitted, and 112 (25.6%) received NSC. On multivariate analysis, CCS was the only predictor of acute h-CT (odds ratio [OR] =1.6; 95% confidence interval [CI]: 1.3–2.0; P < 0.0001) and the best predictor of admission (OR = 1.6; 95% CI: 1.3–1.9; P < 0.0001) and NSC (OR = 1.8; 95% CI: 1.5–2.3; P < 0.0001).

Conclusions:

One-third of intoxicated trauma patients have acute findings on h-CT. While the CCS was the best predictor of acute h-CT findings, hospital admission, and NSC, h-CT scanning should continue to be a standard of care.

Expert-level detection of acute intracranial hemorrhage on head computed tomography using deep learning

Computed tomography (CT) of the head is the workhorse medical imaging modality used worldwide to diagnose neurologic emergencies. However, these gray scale images are limited by low signal-to-noise, poor contrast, and a high incidence of image artifacts. A unique challenge is to identify tiny subtle abnormalities in a large 3D volume with near-perfect sensitivity. We used a single-stage, end-to-end, fully convolutional neural network to achieve accuracy levels comparable to that of highly trained radiologists, including both identification and localization of abnormalities that are missed by radiologists.

Computed tomography (CT) of the head is used worldwide to diagnose neurologic emergencies. However, expertise is required to interpret these scans, and even highly trained experts may miss subtle life-threatening findings. For head CT, a unique challenge is to identify, with perfect or near-perfect sensitivity and very high specificity, often small subtle abnormalities on a multislice cross-sectional (three-dimensional [3D]) imaging modality that is characterized by poor soft tissue contrast, low signal-to-noise using current low radiation-dose protocols, and a high incidence of artifacts. We trained a fully convolutional neural network with 4,396 head CT scans performed at the University of California at San Francisco and affiliated hospitals and compared the algorithm’s performance to that of 4 American Board of Radiology (ABR) certified radiologists on an independent test set of 200 randomly selected head CT scans. Our algorithm demonstrated the highest accuracy to date for this clinical application, with a receiver operating characteristic (ROC) area under the curve (AUC) of 0.991 ± 0.006 for identification of examinations positive for acute intracranial hemorrhage, and also exceeded the performance of 2 of 4 radiologists. We demonstrate an end-to-end network that performs joint classification and segmentation with examination-level classification comparable to experts, in addition to robust localization of abnormalities, including some that are missed by radiologists, both of which are critically important elements for this application.

Emergency Department Use of Neuroimaging in Children and Adolescents Presenting with Headache

OBJECTIVES

To evaluate emergency department use and outcomes of neuroimaging for headache in a free-standing children's hospital system.

STUDY DESIGN

We prospectively enrolled children aged 6-18 years who presented to the emergency department with a chief complaint of headache from September 2015 to September 2016. Standardized data collection was performed in real time, including telephone follow-up as needed, and imaging outcome was determined through a chart review. Using multivariable logistic regression, we estimated the associations between clinically important patient characteristics and neuroimaging.

RESULTS

Of 294 enrolled patients, 53 (18%) underwent neuroimaging (computed tomography or magnetic resonance imaging) and 2 (0.7%) had clinically important intracranial findings. Presenting with abnormal neurologic examination findings (OR, 11.55; 95% CI, 3.24-41.22), no history of similar headaches (OR, 2.13; 95% CI, 1.08-4.18), and white race (OR, 3.04; 95% CI, 1.51-6.12) were significantly associated with an increased odds of undergoing imaging in multivariable regression models.

CONCLUSIONS

Our observed emergency department imaging rate was 26.5 times higher than our positive result rate, suggesting there is room to decrease unnecessary neuroimaging. Associations for abnormal examination and new headache type are consistent with the American Academy of Neurology clinical imaging recommendations. The increased odds of imaging white patients suggests bias that should be addressed. The low rate of positive findings supports the need for an evidence-based clinical decision tool for neuroimaging in the acute care setting.

Concussion and its neurobehavioural sequelae

A concussion results from a force to the brain that results in a transient loss of connectivity within the brain. Sport psychiatrists are increasingly called to be part of the concussion team and need to be prepared to manage issues related to concussion and its behavioural sequelae. Objectively, the best evidence available suggests that deficits in attention and/or in balance are the most reliable objective findings that a concussion has occurred. Prognosis after a concussion is generally very good, although a sub-set of patients that are yet well defined seem pre-disposed to delayed recovery. Neither head CT nor MRI are sufficiently sensitive to diagnose the type of injuries that pre-dispose patients to the neurobehavioural sequelae that have been associated with a concussion; confounding this is the finding that many of these signs and symptoms associated with concussion occur in other types of non-head injuries. Brain biomarkers and functional MRI (fMRI) hold promise in both diagnosis and prognosis of concussion, but are still research tools without validated clinical utility at this time. Finally, neurocognitive testing holds promise as a diagnostic criterion to demonstrate injury but, unfortunately, these tests are also limited in their prognostic utility and are of limited value.

Controversies in the Diagnosis of Subarachnoid Hemorrhage

BACKGROUND

Headache 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.

OBJECTIVE

This 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.

DISCUSSION

Various 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.

CONCLUSIONS

Literature 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.

Intact intracranial breast prosthesis: a 28-year CT follow-up after treatment of late hemispherectomy complications

Anatomical hemispherectomy has had excellent results in treating drug-resistant seizures of infantile hemiplegia. This technique of hemispherectomy consists in the removal of a whole hemisphere, with or without the basal ganglia, the end result being a large cavity left at the end of the operation. The technique, however, is considered to be weighted by important complications, in particular intracranial hemorrhages due to vessels tearing secondary to dislodgement of the remaining hemisphere. Several techniques have been consequently proposed to reduce the volume of the residual hemicranial cavity. An alternative measure is the filling of the cavity itself. We have demonstrated that this type of procedure can be carried out using a silicone breast prosthesis. In this report, we demonstrate also that such an implant can have a surprisingly long duration in its unusual location.

Head computed tomography is not useful for evaluating patients change in mental status following total joint arthroplasty

We retrospectively reviewed 187 patients who presented with neurologic abnormality after total joint arthroplasty to establish the incidence of diagnosed organic brain disorders in these patients and determine the utility of advanced head imaging studies. 139 of 187 (74.3%) patients underwent imaging for altered mental status (AMS) and 48 patients for a focal neurologic deficit (FND). Acute findings on head imaging were more common in the FND group. The incidence of stroke and transient ischemic attack was significantly lower in the AMS group compared to FND group (Stroke: 0% vs 12.5%, p < 0.001; TIA: 0% vs. 16.7%, P < .001). Advanced head imaging for evaluation of TJA patients with a change in mental status is of low yield. An algorithm for evaluation of these patients is proposed.

Combined multi-kernel head computed tomography images optimized for depicting both brain parenchyma and bone

BACKGROUND

The hybrid convolution kernel technique for computed tomography (CT) is known to enable the depiction of an image set using different window settings.

OBJECTIVE

Our purpose was to decrease the number of artifacts in the hybrid convolution kernel technique for head CT and to determine whether our improved combined multi-kernel head CT images enabled diagnosis as a substitute for both brain (low-pass kernel-reconstructed) and bone (high-pass kernel-reconstructed) images.

METHODS

Forty-four patients with nondisplaced skull fractures were included. Our improved multi-kernel images were generated so that pixels of >100 Hounsfield unit in both brain and bone images were composed of CT values of bone images and other pixels were composed of CT values of brain images. Three radiologists compared the improved multi-kernel images with bone images.

RESULTS

The improved multi-kernel images and brain images were identically displayed on the brain window settings. All three radiologists agreed that the improved multi-kernel images on the bone window settings were sufficient for diagnosing skull fractures in all patients.

CONCLUSIONS

This improved multi-kernel technique has a simple algorithm and is practical for clinical use. Thus, simplified head CT examinations and fewer images that need to be stored can be expected.