Anatomy and Pathology of the Skull Base: Malignant and Nonmalignant Lesions.

The skull base (SB) is the osseous foundation of the cranial vault. It contains many openings that allow communication between the extracranial and intracranial structures. This communication is crucial in normal physiologic processes yet may also arrow spread of disease. This article provides a comprehensive review of SB anatomy including important landmarks and anatomic variants relevant to SB surgery. We also illustrate the diverse pathologies affecting the SB.

Cervical MRI assessment of traumatic anterior atlanto-occipital membrane complex injuries with evaluation of ancillary findings.

BACKGROUND AND PURPOSE: The purpose of this study was to identify and classify the different types of anterior atlanto-occipital membrane complex injuries on MRI and evaluate for the presence, size, and location of a prevertebral effusion on the preceding CT exams. MATERIALS AND METHODS: Patients who suffered an anterior atlanto-occipital membrane complex injury were identified retrospectively utilizing Nuance mPower software. An anatomic-based description of the location of the anterior atlanto-occipital membrane complex injury was recorded along with any additional osteoligamentous trauma of the craniocervical junction. The preceding cervical CT exams for these patients were reviewed for the presence and location of a prevertebral effusion. RESULTS: Fifty patients were identified with an acute, post-traumatic anterior atlanto-occipital membrane complex injury. Three distinct patterns of anterior atlanto-occipital membrane complex injury were observed. Nineteen patients demonstrated increased STIR signal with disruption of the anterior atlanto-occipital membrane, ten patients demonstrated increased STIR signal with disruption of the anterior atlanto-axial membrane, and twenty-one patients demonstrated increased STIR signal with disruption of both the anterior atlanto-occipital membrane and anterior atlanto-axial membrane. An effusion at the C1-C2 level was present in greater than 90% of patients with anterior atlanto-occipital membrane complex injury. CONCLUSIONS: The presence of a craniocervical prevertebral effusion on CT in trauma patients may raise suspicion for an injury to the anterior atlanto-occipital membrane complex and potentially trigger additional investigation with cervical MRI.

Prognosticators of Visual Acuity After Indirect Traumatic Optic Neuropathy.

BACKGROUND: The purpose of this study is to determine whether there are radiographic and systemic clinical characteristics that can predict final visual outcomes in patients with indirect traumatic optic neuropathy (iTON). METHODS: This study is a retrospective, multicenter case series of adult patients with iTON treated initially at large, urban, and/or academic trauma centers with follow-up at an affiliated ophthalmology clinic. In addition to detailed cranial computed tomography characteristics, demographics, systemic comorbidities, coinjuries, blood products administered, and intracranial pressure, along with other factors, were gathered. LogMAR visual acuity (VA) at the initial presentation to the hospital and up to 12 months follow-up was collected. RESULTS: Twenty patients met inclusion criteria; 16 (80%) were men with a mean age of 40.9 years (±20.9). Mean initial VA was 1.61 logMAR (∼20/800, ± 0.95), and final VA was 1.31 logMAR (∼20/400, ± 1.06). Three patients (4 eyes) had no light perception (NLP) VA at presentation and remained NLP at final follow-up. Of the predictors analyzed, only the initial VA was found to be a significant predictor of visual outcome. The presence of orbital fractures, intraconal and/or extraconal hemorrhage, as well as systemic comorbidities, were not found to significantly affect visual outcome. CONCLUSIONS: After evaluating multiple factors, initial VA was the only factor associated with visual prognosis in iTON. This knowledge may better enable clinicians to predict visual prognosis and set reasonable expectations with patients and families at the time of injury.

It's Not All in Your Head: Thoracic Manifestations of Neurologic Diseases and Disorders.

Myriad conditions may affect both the neurologic system and the thorax, while other diseases primarily affecting the thorax may manifest with neurologic abnormalities. Correlation of signs, symptoms, and imaging findings in the neurological system with those in the thorax can help diagnose certain conditions and/or guide further diagnostic work-up and treatment. We will review and illustrate the imaging appearance of several systemic/neurological diseases with thoracic manifestations as well as discuss conditions in the thorax that can lead to neurologic symptoms.

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.

A Unique Radiologic Case of Optic Nerve Infarction in a Patient With Mucormycosis.

ABSTRACT: This is a rare presentation of a unilateral optic nerve infarction of the left eye caused by mucormycosis in a 51-year-old man with poorly controlled Type 2 diabetes. Diffusion-weighted MRI of the orbit demonstrated extensive infarction of the left optic nerve with ipsilateral cavernous sinus thrombosis and periorbital adnexal inflammation. Left orbital exenteration and sinus debridement were performed, and mucormycosis involving the optic nerve sheath was confirmed on histopathology.

Therapeutic and Diagnostic Challenges in Myasthenia Gravis.

"Myasthenia gravis (MG) is the most common autoimmune neuromuscular disorder. This article highlights several cases that the practicing neurologist may encounter in the treatment of MG. Diagnostic uncertainty continues to be an issue in patients who are seronegative to the 2 most common antibodies, acetylcholine receptor and muscle-specific tyrosine kinase (MuSK). Specific populations of patients with MG including MuSK MG, thymomatous MG, refractory MG, and pregnant women also require special consideration. This article reviews specific cases and an update on current management."

Burkitt lymphoma masquerading as Tolosa-Hunt syndrome in an HIV-seropositive patient.

PURPOSE: To describe a rare case of Burkitt lymphoma metastatic to the cavernous sinus that was initially diagnosed as Tolosa-Hunt syndrome. CASE DESCRIPTION: A 31-year-old confirmed and treatment-compliant HIV-positive Hispanic male acutely developed diplopia, ptosis, numbness in the V1 distribution, and complete external ophthalmoplegia in the right eye over 1 week. Imaging showed a mass-like lesion within the right cavernous sinus without other intracranial abnormalities. He was started on broad-spectrum antibiotics and antifungals without improvement. Inflammatory and infectious workup was negative. A presumed diagnosis of Tolosa-Hunt syndrome was made based on clinical and radiographic findings, as well as the absence of another etiology to explain the patient's presentation. He was then started on high-dose oral steroids with improvement of orbital pain only. Shortly after being discharged on steroids, the patient returned to the hospital with severe abdominal pain. Computed tomography of the abdomen showed perforated ileitis with aneurysmal dilation of the ileum and marked wall thickening concerning for a mass lesion. Positron emission tomography-computed tomography showed an uptake in the terminal ileum and right cavernous sinus consistent with metastatic Burkitt lymphoma, matching with pathology. After several cycles of chemotherapy, symptoms improved, and he regained full ocular motility in the affected eye. However, the patient ultimately died due to peritonitis and pyelonephritis. CONCLUSION: Burkitt lymphoma metastatic to the cavernous sinus was diagnosed after an initial diagnosis of Tolosa-Hunt syndrome. Tolosa-Hunt syndrome is a diagnosis of exclusion and should only be made after ruling out other pathologies.

Idiopathic Central Nervous System Inflammatory Disease in the Setting of HLA-B27 Uveitis.

Purpose: The purpose of the article is to describe a novel case of idiopathic central nervous system inflammatory disease with bilateral human leukocyte antigen (HLA)-B27-positive anterior uveitis. Methods/Results: A 15-year-old African American boy with bilateral HLA-B27-positive anterior uveitis controlled with topical and oral steroids for 8 months acutely developed headaches, left eyelid ptosis, and binocular diplopia. Imaging showed lesions in the right midbrain, superior colliculus, cerebellar peduncles, and cerebellar vermis and leptomeningeal enhancement along the vermian foliae. Cerebral spinal fluid tests showed mild lymphohistiocytic pleocytosis with negative cytology; inflammatory and infectious workup were negative. He received intravenous methylprednisolone without initial symptomatic improvement; repeat magnetic resonance imaging (MRI) showed reduced lesion burden. Oral steroids were continued; his symptoms resolved in 1 month. Repeat MRI 2 months after presentation showed almost complete lesion resolution. Conclusions: Chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids (CLIPPERS) was diagnosed. HLA-B27 positivity may represent a novel association with CLIPPERS.

Orbitocerebral Mucormycosis in a Patient With Central Nervous System Lymphoma.

A 61-year-old man with well-controlled diabetes mellitus type 2, cirrhosis from hepatitis C, alcohol abuse, and portal hypertension presented with painful vision loss and left orbital swelling. Imaging showed diffuse orbital, perineural, and pachymeningeal inflammation. He was initially diagnosed with neurosarcoidosis. However, cerebrospinal fluid analysis revealed central nervous system lymphoma, and lacrimal gland biopsy showed fungal organisms consistent with mucormycosis. The authors describe a case of Mucorales infection lacking sinonasal involvement and discuss the differential diagnosis and management of patients presenting with orbital and central nervous system inflammation from this uncommon fungal infection.

Accuracy of Computed Tomography Imaging Criteria in the Diagnosis of Adult Open Globe Injuries by Neuroradiology and Ophthalmology.

OBJECTIVE: The objective was to evaluate the sensitivity and specificity of computed tomography (CT) diagnosis of open globes, determine which imaging factors are most predictive of open globe injuries, and evaluate the agreement between neuroradiologist and ophthalmologist readers for diagnosis of open and closed globes. METHODS: This study was a retrospective cohort study. Patients who presented to Memorial Hermann-Texas Medical Center with suspicion for open globes were reviewed. One neuroradiologist and two ophthalmologists masked to clinical information reviewed CT images for signs concerning for open globe including change in globe contour, anterior chamber deformation, intraocular air, vitreous hemorrhage, subretinal fluid indicating retinal or choroidal detachment, dislocated or absent lens, intraocular foreign body, and orbital fracture. Using the clinically or surgically confirmed globe status as the true globe status, sensitivity, specificity, and agreement (kappa) were calculated and used to investigate which imaging factors are most predictive of open globe injuries. RESULTS: A total of 114 patients were included: 35 patients with open globes and 79 patients with closed globes. Specificity was greater than 97% for each reader, and sensitivity ranged from 51% to 77% among readers. The imaging characteristics most consistently used to predict an open globe injury were change in globe contour and vitreous hemorrhage (sensitivity = 43% to 57%, specificity > 98%). The agreement of impression of open globe between the neuroradiologist and ophthalmologists was good and excellent between ophthalmologists. CONCLUSIONS: Computed tomography imaging is not absolute, and the sensitivity is still inadequate to be fully relied upon. The CT imaging findings most predictive of an open globe injury were change in globe contour and vitreous hemorrhage. Clinical examination or surgical exploration remains the most important component in evaluating for a suspected open globe, with CT imaging as an adjunct.

Dizziness in a community hospital: central neurological causes, clinical predictors, and diagnostic yield and cost of neuroimaging studies.

Objectives: Neuroimaging is contributing to the rising costs of dizziness evaluation. This study examined the rate of central neurological causes of dizziness, relevant clinical predictors, and the costs and diagnostic yields of neuroimaging in dizziness assessment. Methods: We retrospectively reviewed the records of 521 adult patients who visited the hospital during a 12-month period with dizziness as the chief complaint. Clinical findings were analyzed using Fisher's exact test to determine how they correlated with central neurological causes of dizziness identified by neuroimaging. Costs and diagnostic yields of neuroimaging were calculated. Results: Of the 521 patients, 1.5% had dizziness produced by central neurological causes. Gait abnormalities, limb ataxia, diabetes mellitus, and the existence of multiple neurological findings predicted central causes. Cases were associated with gait abnormalities, limb ataxia, diabetes mellitus, and the existence of multiple neurological findings . Brain computed tomography (CT) and magnetic resonance imaging (MRI) were performed in 42% and 9.5% of the examined cases, respectively, with diagnostic yields of 3.6% and 12%, respectively. Nine cases of dizziness were diagnosed from 269 brain scans, costing $607 914. Conclusion: Clinical evaluation can predict the presence of central neurological causes of dizziness, whereas neuroimaging is a costly and low-yield approach. Guidelines are needed for physicians, regarding the appropriateness of ordering neuroimaging studies. Abbreviations: OR: odds ratio; CI: confidence interval; ED: emergency department; CT: computed tomography; MRI: magnetic resonance imaging; HINTS: Head impulse, Nystagmus, Test of skew.

Endovascular Therapy for Acute Ischemic Stroke With Occlusion of the Middle Cerebral Artery M2 Segment.

IMPORTANCE: Randomized clinical trials have shown the superiority of endovascular therapy (EVT) compared with best medical management for acute ischemic strokes with large vessel occlusion (LVO) in the anterior circulation. However, of 1287 patients enrolled in 5 trials, 94 with isolated second (M2) segment occlusions were randomized and 51 of these received EVT, thereby limiting evidence for treating isolated M2 segment occlusions as reflected in American Heart Association guidelines. OBJECTIVE: To evaluate EVT safety and effectiveness in M2 occlusions in a cohort of patients with acute ischemic stroke. DESIGN, SETTING, AND PARTICIPANTS: This multicenter retrospective cohort study pooled patients with acute ischemic strokes and LVO isolated to M2 segments from 10 US centers. Patients with acute ischemic strokes and LVO in M2 segments presenting within 8 hours from their last known normal clinical status (LKN) from January 1, 2012, to April 30, 2015, were divided based on their treatment into EVT and medical management groups. Logistic regression was used to compare the 2 groups. Univariate and multivariate analyses evaluated associations with good outcome in the EVT group. MAIN OUTCOMES AND MEASURES: The primary outcome was the 90-day modified Rankin Scale score (range, 0-6; scores of 0-2 indicate a good outcome); the secondary outcome was symptomatic intracerebral hemorrhage. RESULTS: A total of 522 patients (256 men [49%]; 266 women [51%]; mean [SD] age, 68 [14.3] years) were identified, of whom 288 received EVT and 234 received best medical management. Patients in the medical management group were older (median [interquartile range] age, 73 [60-81] vs 68 [56-78] years) and had higher rates of intravenous tissue plasminogen activator treatment (174 [74.4%] vs 172 [59.7%]); otherwise the 2 groups were balanced. The rate of good outcomes was higher for EVT (181 [62.8%]) than for medical management (83 [35.4%]). The EVT group had 3 times the odds of a good outcome as the medical management group (odds ratio [OR], 3.1; 95% CI, 2.1-4.4; P < .001) even after adjustment for age, National Institute of Health Stroke Scale (NIHSS) score, Alberta Stroke Program Early Computed Tomographic Score (ASPECTS), intravenous tissue plasminogen activator treatment, and time from LKN to arrival in the emergency department (OR, 3.2; 95% CI, 2-5.2; P < .001). No statistical difference in symptomatic intracerebral hemorrhage was found (5.6% vs 2.1% for the EVT group vs the medical management group; P = .10). The treatment effect did not change after adjusting for center (OR, 3.3; 95% CI, 1.9-5.8; P < .001). Age, NIHSS score, ASPECTS, time from LKN to reperfusion, and successful reperfusion score of at least 2b (range, 0 [no perfusion] to 3 [full perfusion with filling of all distal branches]) were independently associated with good outcome of EVT. A linear association was found between good outcome and time from LKN to reperfusion. CONCLUSIONS AND RELEVANCE: Although a randomized clinical trial is needed to confirm these findings, available data suggest that EVT is reasonable, safe, and effective for LVO of the M2 segment relative to best medical management.

Magnetic resonance imaging (MRI) in the diagnosis of head and neck disease.

Magnetic resonance imaging (MRI) is the modality of choice to identify intracranial or perineural spread from a head and neck primary tumor. Perineural spread is a form of metastatic disease in which primary tumors spread along neural pathways. Orbital cellulitis is a sight-threatening, and potentially life-threatening condition. Urgent imaging is performed to assess the anatomic extent of disease, including postseptal, cavernous sinus, and intracranial involvement, and identify orbital abscesses that require exploration and drainage. MRI is useful in the evaluation of the brachial plexus.

Case of "slow" stroke from carotid artery occlusion treated by delayed but cautious endovascular intervention.

In a challenging case of carotid occlusion with slowly evolving stroke, we used brain imaging to facilitate endovascular revascularization resulting in the relief of the patient's symptoms. Patients with carotid occlusion and continued neurological worsening or fluctuations present enormous treatment challenges. These patients may present "slow" strokes with subacute infarcts that present significant challenges and risks during attempts at revascularization of the occluded artery. We present such a case in which we used multimodal imaging techniques, including MR-perfusion, to facilitate endovascular revascularization. Our approach of delayed but cautious intra-arterial thrombolytic therapy, guided by brain imaging, and followed by stent placement across the residual stenosis, enabled revascularization of the occluded artery without overt in-hospital complications.