Is Contrast-Enhanced Computed Tomography Redundant for Suspected Intracranial Infection in the Emergency Setting?

OBJECTIVE: There are currently no guidelines for when to use intravenous contrast with head computed tomography (CT) when there is suspected acute intracranial infection. The purpose of our study was to determine the proportion of cases with enhancing findings on CT that also have conspicuous correlating associated findings on noncontrast CT, which would have on their own merited further evaluation with magnetic resonance imaging, the criterion standard for evaluating central nervous system pathology. METHODS: A retrospective keyword search of the history and clinical information fields in radiology reports for CT examinations of the head without and with contrast from the period January 1, 2004, to October 31, 2021 was performed. Patients with prior head surgery or a history of cancer were excluded. For remaining patients, the noncontrast CT was reviewed for vasogenic edema or mass effect as markers of a possible acute infection, and the presence of background hypodense white matter changes was noted and graded as either absent, mild/scattered, or confluent. Subsequently, the companion contrast-enhanced CT was reviewed for an enhancing abnormality. Chart review was performed to confirm that an infectious process was the ultimate clinical diagnosis in patients with enhancing abnormalities. RESULTS: Of 343 patients meeting study inclusion/exclusion criteria, 39 had acute infections with an enhancing abnormality on CT (prevalence 11.3%). Thirty-two of these 39 patients also had correlative findings on the noncontrast CT. Noncontrast CT had a positive predictive value of 100%, negative predictive value of 97.7%, sensitivity of 82.1%, specificity of 100%, and accuracy of 98.0% for detecting markers (vasogenic edema and/or mass effect) associated with an enhancing abnormality. Vasogenic edema was the most common noncontrast CT finding in patients who had an infectious enhancing lesion (32 of 39), followed by mass effect (22 of 39). The 7 cases where the acute infection was occult on noncontrast CT were due to leptomeningitis (n = 3), confluent background white matter changes masking the vasogenic edema surrounding intra-axial lesions (n = 3), and a small 0.5 cm extra-axial abscess. CONCLUSIONS: Most acute intracranial infections with an enhancing CT finding also have a correlative conspicuous noncontrast finding that on its own would merit further evaluation with magnetic resonance imaging, the criterion standard for investigating central nervous system disease, and therefore, in the setting of suspected intracranial infection, contrast-enhanced CT is redundant in most cases. Contrast-enhanced CT primarily provides diagnostic benefit in patients with confluent background white matter changes that may mask vasogenic edema on noncontrast CT.

Can Anterior Osteophyte Fractures Be Distinguished From Fracture Mimics in the Subaxial Cervical Spine? A Retrospective Analysis Evaluating Reported Fractures With Clinical Management Correlation.

OBJECTIVE: This study aimed to retrospectively distinguish true- from false-positive fractures of anterior subaxial cervical osteophytes, which were reported on noncontrast computed tomography reports, and to correlate the imaging findings with patient symptoms and analyze the downstream impact on management of both true and false positive fractures. METHODS: A total of 127 patients had computed tomography reports of anterior osteophyte fractures. Radiology reports and imaging studies were evaluated to distinguish true fractures from fracture mimics. We analyzed imaging features including rigid spine (RS), prevertebral soft tissue swelling (PVSTS), and instability. We categorized symptoms and examination findings into 3 groups (0, asymptomatic; 1, neck pain; 2, neurological symptoms). Management was categorized into 3 groups (0, no treatment; 1, external bracing; 2, surgery). Associations between imaging features, fracture classification, clinical symptoms, magnetic resonance imaging utilization, and management were calculated using χ2 with Cramer V test to determine effect size. RESULTS: Eighty patients had false-positive fractures, and 47 were true positive. There were significant associations between magnetic resonance imaging utilization and fracture classification (P ≤ 0.001), PVSTS (P ≤ 0.005), patient symptoms (P ≤ 0.001), and patient management (P ≤ 0.001). There were significant associations between patient management and fracture classification (P ≤ 0.001), patient symptoms (P ≤ 0.001), PVSTS (P ≤ 0.001), imaging findings of instability (P ≤ 0.001), and RS (P ≤ 0.021). There were significant associations between fracture classification and patient symptoms (P ≤ 0.045), and RS (P ≤ 0.006). CONCLUSIONS: Subaxial isolated anterior osteophyte fractures fell into 3 major categories. By our methodology, if a suspected fracture was determined to be a fracture mimic in an asymptomatic patient, it was unlikely to be clinically significant. Isolated anterior osteophyte fractures without neurological symptoms or more concerning imaging findings can be treated conservatively. Finally, fractures that demonstrate indirect signs of instability or are associated with RS are more associated with surgical management.

Occult craniocervical dissociation on cervical CT: an under-appreciated presentation of craniocervical trauma requiring occipital cervical fusion.

BACKGROUND AND PURPOSE: Craniocervical dissociation is a rare and life-threatening injury that results from a significant hyperflexion-hyperextension force. Occult craniocervical dissociation is defined as an unstable craniocervical injury in the absence of atlanto-occipital joint space widening or other skull base line abnormality. The early and accurate diagnosis of craniocervical dissociation is crucial since the early diagnosis and subsequent stabilization with occipital-cervical fusion has been shown to reduce neurologic morbidity and mortality. Several normative skull base lines have been developed to predict craniocervical dissociation. The purpose of our study was to measure the atlanto-occipital joint space and four other common skull base lines in patients who underwent occipital-cervical fusion for post-traumatic craniocervical instability. MATERIALS AND METHODS: Patients who underwent occipital-cervical fusion for craniocervical injury were identified retrospectively using a keyword search of radiology reports using Nuance mPower software. The cervical CT and MRI exams for these patients were reviewed and the atlanto-occipital joint space, Powers ratio, Wackenheim line, posterior axial line, and basion dens interval were measured. Detailed descriptions of craniocervical ligament injuries on MRI were recorded along with patient demographic information, clinical history, management, and outcome. RESULTS: Nine adult patients who underwent occipital-cervical fusion for an acute craniocervical injury were identified. Six patients demonstrated an atlanto-occipital joint space measuring 2 mm or less on cervical spine CT with no additional abnormality in the Powers ratio, Wackenheim line, posterior axial line, or basion-dens interval. Three patients demonstrated widening of the atlanto-occipital joint space with two patients demonstrating an abnormality in at least two additional skull base lines. Clinical outcomes were variable with nearly half of the patients demonstrating persistent neurologic deficits, including one quadriplegic patient. CONCLUSIONS: A normal atlanto-occipital joint space and skull base line measurements on cervical CT demonstrated a low predictive value for detecting unstable craniocervical injuries. Occult craniocervical dissociation was present in two-thirds of patients who underwent occipital cervical fusion for acute, craniocervical trauma. A high clinical and radiologic index of suspicion for craniocervical trauma with subsequent follow-up cervical MRI to directly evaluate ligamentous integrity is necessary to accurately diagnose and triage patients with high velocity trauma.

Imaging of dental infections.

Dental infections are a common presentation in the emergency department (ED). To help guide clinical management for these infections, the radiologist must be familiar with the anatomy of the oral cavity and neighboring structures, the range of appearance of dental infections, and the routes along which they may spread. Computed tomography (CT) is often performed when severe dental infections are suspected. This pictorial essay reviews the anatomy pertinent to the imaging evaluation of dental infections and depicts a spectrum of pathology that may be encountered, ranging from simple dentoalveolar infections to complex multispatial infections.

"Supradental space sign" on cervical spine CT-a sign of tectorial membrane injury in adults trauma patients.

BACKGROUND AND PURPOSE: The supradental space is a small, predominantly fat-filled recess superior to the atlanto-axial joint and inferior to the basion of the clivus that contains a small venous plexus. The posterior boundary of the supradental space is formed by the tectorial membrane, a stabilizing ligament of the craniocervical junction. The purpose of our study was to examine the imaging appearance of the supradental space in patients with tectorial membrane injury. MATERIALS AND METHODS: Adult patients with tectorial membrane injury were identified utilizing keyword searches of radiology reports using Nuance mPower software. Age-matched positive and negative control groups were obtained. Two CAQ-certified neuroradiologists evaluated the cervical CT exams of these patients for supradental fat pad effacement from hematoma formation. The integrity of the osteoligamentous structures of the craniocervical junction was recorded on CT and MRI exams along with demographic information, clinical history, surgical management, and global outcome. Statistical analysis was performed. RESULTS: Sixteen adults were diagnosed with tectorial membrane injury on cervical MRI. All patients with a visible supradental space demonstrated fat pad effacement and Hounsfield units consistent with hematoma formation. The positive and negative control groups demonstrated supradental fat pad effacement in 2/16 and 1/16 patients, respectively. A p-value of < 0.001 was obtained. CONCLUSION: The "supradental space sign," defined as hematoma formation in the supradental space with effacement of the supradental fat pad is associated with tectorial membrane injury in adult trauma patients with sensitivity of 93.75% (95% confidence interval 69.77 to 99.84%) and specificity of 90.62% (95% confidence interval 74.98 to 98.02%).

Imaging Review of the Endoscopic Operative Corridor for Clivus Lesions.

Traditional transcranial approaches for lesions involving the clivus, in particular skull base chordoma have several disadvantages for midline skull base lesions as compared to the endoscopic endonasal approach (EEA), such as higher morbidity and lesser extent of resection. These disadvantages led to the development of endoscopic skull-base approaches to access pathology that involves the anterior cranial fossa, central skull base, and lower skull base lesions. In particular, lesions of the clivus are well suited for EEA. Surgical access of the clivus falls into 2 stages: the endonasal approach for access, and the endonasal resection of tumor. The objective of this article is to review the anatomy along the operative corridor for the purpose of image interpretation in preoperative planning in the context of EEA. We provide an imaging review of the sinonasal anatomy used for access by otolaryngologists and the anatomy of the clivus used by neurosurgeons for preoperative planning and resection.

Shiga toxins induce autophagy leading to differential signalling pathways in toxin-sensitive and toxin-resistant human cells.

The bacterial virulence factors Shiga toxins (Stxs) are expressed by Shigella dysenteriae serotype 1 and certain Escherichia coli strains. Stxs are protein synthesis inhibitors and induce apoptosis in many cell types. Stxs induce apoptosis via prolonged endoplasmic reticulum stress signalling to activate both extrinsic and intrinsic pathways in human myeloid cells. Studies have shown that autophagy, a lysosome-dependent catabolic process, may be associated with activation of pro-survival or death processes. It is currently unknown if autophagy contributes to apoptosis or protects cells from Stxs. To study cellular responses to Stxs, we intoxicated toxin-sensitive cells (THP-1 and HK-2 cells), and toxin-resistant cells (primary human monocyte-derived macrophages) and examined toxin intracellular trafficking and autophagosome formation. Stxs translocated to different cell compartments in toxin-resistant versus toxin-sensitive cells. Confocal microscopy revealed autophagosome formation in both toxin-resistant and toxin-sensitive cells. Proteolytic cleavage of Atg5 and Beclin-1 plays pivotal roles in switching non-cytotoxic autophagy to cell death signalling. We detected cleaved forms of Atg5 and Beclin-1 in Stx-treated toxin-sensitive cells, while cleaved caspases, calpains, Atg5 and Beclin-1 were not detected in toxin-resistant primary human monocytes and macrophages. These findings suggest that toxin sensitivity correlates with caspase and calpain activation, leading to Atg5 and Beclin-1 cleavage.

Meningiomas Can Present as Intracranial Hemorrhage in Rare Cases: A Case Report of a Patient With a History of Minor Trauma and Massive Intracranial Hemorrhage.

Meningiomas are relatively common intracranial tumors. While typically discovered incidentally or related to symptoms from regional mass effect, on rare occasions, they can present as acute intracranial hemorrhage. We report a case of a 62-year-old male who presented with significant acute intracranial hemorrhage with a history of minor trauma. Imaging workup demonstrated a hemorrhagic mass to be the likely cause of the hemorrhage. Upon resection of the mass, pathology demonstrated meningioma. It is important to thoroughly investigate intracranial hemorrhage, particularly when it appears out of proportion to any known causative event, in order to accurately diagnose, manage, and treat these patients.

Interrelationship Between Craniocervical Dissociation Spectrum Injuries and Atlantoaxial Instability on Trauma Cervical MRI Examinations.

Background and purpose Craniocervical dissociation injuries encompass a spectrum of osteoligamentous injuries between the skull base and C1-C2 that may be treated via prolonged external immobilization versus occipital cervical fusion depending on the risk of persistent craniocervical instability. However, the presence of atlantoaxial instability (AAI) at C1-C2, as determined by transverse atlantal ligament (TAL) integrity with or without a C1 fracture, may guide the neurosurgical management of craniocervical dissociation spectrum injuries (CDSI) since it implies an overall greater degree of instability at the craniocervical junction (CCJ). Materials and methods Adult trauma patients who suffered a transverse atlantal ligament injury on cervical magnetic resonance imaging (MRI) were identified retrospectively. The cervical computed tomography (CT) and magnetic resonance imaging examinations for these patients were reviewed for additional traumatic findings. Demographic information, treatment, and outcome information were recorded. Results Twenty-nine trauma patients presented to the emergency department (ED) with an acute, midsubstance transverse atlantal ligament tear on cervical magnetic resonance imaging. Thirty-one percent of patients demonstrated a tear in at least one major craniocervical ligament (atlanto-occipital capsular ligaments, alar ligaments, and tectorial membrane {TM}) with 14% demonstrating a tear in two major craniocervical ligaments and no patients demonstrating a tear in all three major craniocervical ligaments. Minor craniocervical ligament injuries (anterior atlanto-occipital membrane complex {AAOMc} and posterior atlanto-occipital membrane complex {PAOMc}) were common and observed in 76% of patients. Conclusions Our study suggests that multiple major craniocervical junction ligamentous injuries on cervical magnetic resonance imaging are relatively uncommon in the setting of transverse atlantal ligament injury.

Radiologic utility of the Gehweiler and AO spine classification systems for C1 Trauma: A retrospective review from a Level I trauma center.

Objective: The purpose of our study was to identify adult trauma patients with an acute C1 burst fracture, evaluate for concomitant transverse atlantal ligament (TAL) injury, and apply the modified Gehweiler and AO spine classification systems to determine the utility of these classification systems in accurately defining C1 trauma. Materials and Methods: Adult trauma patients with an acute C1 fracture were identified retrospectively using Nuance mPower software. The C1 fracture was described based on whether the fracture involved the anterior arch, posterior arch, lateral mass, medial tubercle, and/or transverse process. If follow-up cervical magnetic resonance imaging (MRI) was performed, the presence and location of an associated TAL injury was recorded. The anatomic location of the C1 burst fracture and TAL injury, if present, were compared with the descriptive classification systems outlined by Gehweiler/Dickman (modified) and the AO Spine society. Any additional osseous trauma of the skull base and C1-C2 was also recorded along with relevant clinical history and management. Results: Thirty-nine patients were identified with an acute C1 burst fracture on cervical computed tomography (CT) with seventy-seven percent of patients undergoing follow-up cervical MRI. Observed fracture patterns were divided into five distinct types based on CT findings and further subdivided based on the integrity of the transverse altantal ligament on MRI. TAL tears were observed exclusively in type 3 fractures (anterior and posterior arch fractures) and type 4 fractures (anterior arch, posterior arch, and lateral mass fractures). The modified Gehweiler classification system failed to accurately describe the anatomic location of the C1 fracture in forty-four percent of patients, whereas the AO spine was too broad and failed to accurately describe fracture location in our cohort. Conclusions: The Gehweiler and AO spine classifications demonstrated significant shortcomings in the accurate description of patients with C1 trauma. Whereas the Gehweiler system did not accurately describe the anatomic location of the various C1 fractures, the AO spine system was too broad and failed to radiologically classify fracture location. Moreover, there was a high number of patients with AO spine type B injuries without atlantoaxial translation that nevertheless required C1-C2 fusion for atlantoaxial instability. We suggest the need for an updated classification system that takes into account both the CT (fracture location) and MRI (TAL integrity) appearance of C1 trauma. An updated classification strategy will offer a radiologic standardization of C1 trauma that will aid in future research studies and help optimize patient management.

Appropriateness of Cervical Magnetic Resonance Imaging in the Evaluation and Management of C1 Jefferson Fractures.

BACKGROUND: Traditionally, C1 fractures have been designated as stable or unstable based on the inherent integrity of the transverse altantal ligament. The purpose of our study was to identify adult trauma patients with C1 fractures on cervical computed tomography and evaluate whether C1-C2 alignment differed in patients with and without an associated transverse atlantal ligament injury on follow-up cervical magnetic resonance imaging. METHODS: Adult trauma patients who suffered a C1 fracture were identified retrospectively. The cervical computed tomography examinations for these patients were reviewed for the following: C1 fracture classification, anterior atlantodens interval (ADI) widening, asymmetry in the lateral atlantodens interval, C1 lateral mass offset, and atlantoaxial rotation. RESULTS: Acute C1 fractures were grouped into those with an unequivocal transverse atlantal ligament injury (n = 12), and patients with an unequivocally intact transverse atlantal ligament (n = 20). Three patients were classified as indeterminate for transverse atlantal ligament injury. Statistically significant increases in lateral ADI asymmetry and combined C1 lateral mass offset were identified in patients with transverse atlantal ligament tears. CONCLUSIONS: Lateral ADI asymmetry (using a cutoff of >3 mm), combined C1 lateral mass offset, and anterior ADI demonstrate robust specificity to "rule in" transverse atlantal ligament injury. Atlantoaxial alignment was overall relatively insensitive as a screening test although sensitivity can be improved using a cutoff of >2 mm for lateral ADI asymmetry. Our findings reinforce the role of cervical magnetic resonance imaging in the diagnostic workup and clinical management of trauma patients with an acute burst fracture of the C1 vertebra.

Midbrain Ischemic Strokes Presenting as Isolated Internuclear Opthalmoplegia.

Stroke can present with unique neurologic symptoms, which can be used to help determine the location of the stroke. Internuclear ophthalmoparesis (INO), also known as internuclearophthalmoplegia, is a distinct gaze abnormality with impaired horizontal eye movements with compromised adduction of the affected eye, and abduction nystagmus of the contralateral eye. Infarcts involving the medial longitudinal fasciculus in either the pons or midbrain can result in INO. We present two cases of midbrain ischemic stroke, which presented as isolated INO. The midbrain has a unique and intricate vascular supply including branches from the basilar, superior cerebellar, posterior cerebral, posterior communicating, anterior choroidal, and posterior choroidal arteries, which is reviewed. Infarcts involving the paramedian midbrain, which is supplied by short circumferential arteries and penetrating branches arising from the posterior cerebral artery and superior cerebellar artery, can result in INO.

Tectorial Membrane Injury, Frequently Identified in Adult Trauma Patients Who Undergo Occipital-Cervical Fusion for Craniocervical Instability.

Background In the absence of frank craniocervical dissociation, there is a lack of consensus regarding what patterns of craniocervical junction ligamentous injuries require occipital-cervical fusion. This study was undertaken to examine the integrity of the craniocervical junction ligaments and analyze clinical outcomes in patients who underwent occipital-cervical fusion for craniocervical junction injury. Methods Adult patients requiring occipital-cervical fusion were identified retrospectively utilizing keyword searches in cervical computed tomography and magnetic resonance imaging reports between 2012 and 2020 using Nuance mPower software (Nuance, Burlington, MA). The cervical magnetic resonance imaging examinations for these patients were reviewed for craniocervical ligamentous injury by two neuroradiologists. Descriptions of craniocervical junction injuries, demographic information, clinical history, surgical management, and global outcomes were recorded. Results Nine adult patients were identified with an acute, post-traumatic craniocervical junction injury requiring occipital-cervical fusion. All nine patients demonstrated a ligamentous tear in at least one of the four major craniocervical junction ligaments - the occipital condylar-C1 capsular ligaments, alar ligaments, tectorial membrane, and posterior atlantooccipital membrane. The tectorial membrane was the most commonly torn ligament followed by the alar ligament(s), posterior atlantooccipital membrane, and capsular ligament(s). There was wide variability in the number of major craniocervical junction ligaments torn, ranging from one ligament to all four ligaments. Four patients suffered persistent neurologic deficits following surgery. Conclusion Craniocervical injury is best evaluated by cervical magnetic resonance imaging. In the absence of overt craniocervical dissociation, we propose that an injury of the tectorial membrane in the adult population may indicate patients with significant craniocervical instability, possibly necessitating occipital-cervical fusion.

Endobronchial Tuberculosis and Bronchostenosis: A Rare Case of Bronchial Occlusion in a Patient With History of Tuberculosis.

Pulmonary tuberculosis is common worldwide, and many of these patients develop endobronchial tuberculosis (EBTB). Bronchostenosis is a known complication of EBTB though most patients with endobronchial stenosis do not develop severe bronchostenosis or occlusion. We present a rare case of a patient with a right upper lobe bronchus occlusion and a history of tuberculosis.

Grade III Solitary Fibrous Tumor/Hemangiopericytoma: A Rare Case of a World Health Organization Grade III Anaplastic Hemangiopericytoma.

Solitary fibrous tumors (SFTs) and hemangiopericytomas (HPCs) have been combined into a single designation in the most recent World Health Organization (WHO) guidelines as solitary fibrous tumor/hemangiopericytoma (SFT/HPC). These rare intracranial tumors can present as WHO grade I, II, or III tumors, with the risk of recurrence, metastasis, and mortality worsening with higher-grade tumors. We present a case of a patient with a WHO grade III SFT/HPC with an emphasis on the imaging features that help differentiate this type of tumor from meningiomas, which are much more common and can appear similar. Being able to help differentiate these tumors by their imaging appearance is important to help triage and risk-stratify patient management decisions.

CT Perfusion Protocol for Acute Stroke Expedites Mechanical Thrombectomy.

The evaluation of a patient suspected of having an acute cerebrovascular accident is initiated with computed tomography (CT) and computed tomography angiogram (CTA) cross-sectional imaging of the head. Eligible patients may subsequently receive magnetic resonance imaging (MRI) utilizing a hyperacute stroke protocol. Clinical and imaging selection criteria are used to assess candidates for possible thrombectomy or thrombolysis. Prompt restoration of flow to ischemic regions of the cerebrum may result in improved neurological outcomes. Reducing delays in diagnosis and treatment remains paramount to effective treatment of ischemic cerebrovascular events. In an effort to expedite intra-arterial intervention, we replaced our institutional MRI protocol with a CT perfusion protocol. The amount of time the patient spent undergoing imaging was measured with each protocol and is referred to as "stroke imaging time." The purpose of this study was to compare the difference in the amount of time patients spent undergoing imaging when the acute stroke workup was performed with MRI vs. CT perfusion. Stroke imaging time decreased from an average of 158 minutes to 81 minutes (49%) by substituting CT perfusion for MRI. Utilizing CT perfusion in lieu of MRI in the hyperacute stroke protocol may expedite intra-arterial intervention.

A Rare Case of Dynamic Popliteal Artery Occlusion After Gunshot Injury with Reconstitution of Flow in the Frog-leg Position.

A 16-year-old male was transferred to our institution shortly after a gunshot injury to the right lower extremity. Physical examination was remarkable for two bullet entry points in the right posterior leg. A right lower extremity computed tomography angiogram (CTA) demonstrated a retained bullet fragment in the right popliteal fossa and a 10 centimeter (cm) in length occlusion of the proximal peroneal artery with reconstitution of flow distally. A diagnostic angiogram of the right lower extremity with the patient's leg extended demonstrated lack of popliteal arterial flow immediately distal to the retained bullet fragment. Reconstitution of vascular flow was appreciated once the patient's leg was placed in the "frog-leg" position.