Cushing Syndrome: Diagnostic Workup and Imaging Features, With Clinical and Pathologic Correlation.

OBJECTIVE: Cushing syndrome (CS) is a constellation of clinical signs and symptoms resulting from chronic exposure to excess cortisol, either exogenous or endogenous. Exogenous CS is most commonly caused by administration of glucocorticoids. Endogenous CS is subdivided into two types: adrenocorticotropic hormone (ACTH) dependent and ACTH independent. CONCLUSION: Cushing disease, which is caused by a pituitary adenoma, is the most common cause of ACTH-dependent CS for which pituitary MRI can be diagnostic, with bilateral inferior petrosal sinus sampling useful in equivocal cases. In ectopic ACTH production, which is usually caused by a tumor in the thorax (e.g., small cell lung carcinoma, bronchial and thymic carcinoids, or medullary thyroid carcinoma) or abdomen (e.g., gastroenteropancreatic neuroendocrine tumors or pheochromocytoma), CT, MRI, and nuclear medicine tests are used for localizing the source of ACTH. In ACTH-independent CS, which is caused by various adrenal abnormalities, adrenal protocol CT or MRI is usually diagnostic.

The Relationship Between Lesion Localization and Dysphagia in Acute Stroke.

Factors that can facilitate early identification of individuals at risk of dysphagia such as stroke location are potentially of great benefit. The aim of this study was to examine the role of hemisphere and lesion location in assessing dysphagia pattern and airway invasion as identified through the use of validated, standardized interpretation measures for the videofluoroscopic swallowing study. Consecutive patients (N = 80) presenting with stroke symptoms who had a first-time acute ischemic stroke confirmed on diffusion-weighted magnetic resonance imaging (DW-MRI) scan participated. Three swallowing outcome variables were assessed using regression models: modified barium swallow impairment profile (MBSImP) oral impairment (OI) and pharyngeal impairment (PI) scores and penetration aspiration scale (PAS) score. Subjects were primarily male and demonstrated mild stroke and mild to moderate dysphagia. There was a significantly higher likelihood of abnormal PAS scores for infratentorial lesions compared to right hemisphere location (Odds ratio: 3.1, SE: 1.8, p = 0.046) and for Whites compared to African Americans (Odds ratio: 5.5, SE: 2.6, p = <0.001). However, OI scores were higher (worse) in African Americans compared to Whites (Beta = -1.2; SE: 0.56; p = 0.037). PI scores had no significant association with race or lesion location. Using DW-MRI to identify infratentorial stroke can help identify individuals at risk of airway invasion; however, imaging information concerning supratentorial infarct hemisphere and location may not be useful to predict which individuals with mild stroke are at risk for dysphagia and aspiration when admitted with acute stroke symptoms. Future studies should explore the role of race in the development of stroke-related dysphagia.

Chronic Effects of Blast-Related TBI on Subcortical Functional Connectivity in Veterans.

OBJECTIVES: Blast explosions are the most frequent mechanism of traumatic brain injury (TBI) in recent wars, but little is known about their long-term effects. METHODS: Functional connectivity (FC) was measured in 17 veterans an average of 5.46 years after their most serious blast related TBI, and in 15 demographically similar veterans without TBI or blast exposure. Subcortical FC was measured in bilateral caudate, putamen, and globus pallidus. The default mode and fronto-parietal networks were also investigated. RESULTS: In subcortical regions, between-groups t tests revealed altered FC from the right putamen and right globus pallidus. However, following analysis of covariance (ANCOVA) with age, depression (Center for Epidemiologic Studies Depression Scale), and posttraumatic stress disorder symptom (PTSD Checklist - Civilian version) measures, significant findings remained only for the right globus pallidus with anticorrelation in bilateral temporal occipital fusiform cortex, occipital fusiform gyrus, lingual gyrus, and cerebellum, as well as the right occipital pole. No group differences were found for the default mode network. Although reduced FC was found in the fronto-parietal network in the TBI group, between-group differences were nonsignificant after the ANCOVA. CONCLUSIONS: FC of the globus pallidus is altered years after exposure to blast related TBI. Future studies are necessary to explore the trajectory of changes in FC in subcortical regions after blast TBI, the effects of isolated versus repetitive blast-related TBI, and the relation to long-term outcomes in veterans. (JINS, 2016, 22, 631-642).

CT angiographic evaluation of the V3 vertebral artery course in cases of occipitalized atlas, a study of 25 cases.

OBJECTIVES: To study the relationship of the 3rd segment of the vertebral artery to the posterior arch of the atlas in patients with occipitalized atlas, using CT angiography. METHODS: A retrospective study of 25 cases with complete or partially occipitalized atlas who underwent CT angiography evaluation. Fifty vertebral arteries were analyzed in relation to the respective/related half of the posterior arch of the atlas. RESULTS: Out of 50 vertebral arteries, 35 (70%) were anomalous; 31 (62%) traversed though bony canal between the fused occiput and atlas, and 4 (8%) coursed between C1 and C2 (C2 segmental type of vertebral artery). Except one, all anomalous vertebral arteries were associated with a fused corresponding side of posterior arch of atlas. CONCLUSION: The V3 portion of the vertebral artery assumes an anomalous course at the craniovertebral junction in most cases of occipitalized atlas, and this is strongly determined by the fusion status of the posterior arch of the atlas. Aberrations in its course are still seen despite expectations based on this fusion status. Preprocedural CT Angiography provides accurate information of its course to prevent iatrogenic VA injuries. ADVANCES IN KNOWLEDGE: CT Angiography should be performed before any procedures at the craniovertebral junction in cases of occipitalized atlas to prevent iatrogenic, potentially catastrophic injuries to vertebral artery due to its anomalous course in most of these cases. There are very few such studies in the literature, none in radiology literature. We also describe some rare cases, including a case never described in any literature.

Alexia Without Agraphia in a Right-Handed Individual Following Right Occipital Stroke.

Alexia without agraphia is a disconnection syndrome that typically involves damage to the occipital lobe, with splenium involvement, in the dominant left hemisphere. We describe an exceptionally rare case of a right-handed individual displaying this deficit following a right-sided occipital stroke. A report of a single case of a 65-year-old man is presented with data from appointments with the neurology and neuropsychology departments that occurred approximately 10 and 12 months following the patient's stroke. During the evaluation, he exhibited a marked deficit in his ability to read, with vision grossly intact. His ability to write single words and short phrases from dictation was intact, but he was later unable to read them. This case demonstrates the complexity of the organization of language in the human brain. Although a large majority of individuals exhibit language dominance in their left hemispheres, it remains possible that some right-handed individuals may show atypical organization of language. This highlights the need for clinicians to consider atypical cortical organization when observed deficits may not necessarily match expected lesions within the cortex.

MRI in the Evaluation of Acute Visual Syndromes.

Acute visual symptom emergencies occur commonly and present a challenge to both clinical and radiologic facets. Although most patients with visual complaints routinely require clinical evaluation with direct ophthalmologic evaluation, imaging is rarely necessary. However, there are highly morbid conditions where the prompt recognition and management of an acute visual syndrome (AVS) requires an astute physician to probe further. Suspicious symptomatology including abrupt visual loss, diplopia, ophthalmoplegia, and proptosis/exophthalmos require further investigation with advanced imaging modalities such as magnetic resonance imaging and magnetic resonance angiography. This review will discuss a variety of AVSs including orbital apex syndrome, cavernous sinus thrombosis, cavernous carotid fistula, acute hypertensive encephalopathy (posterior reversible encephalopathy syndrome), optic neuritis, pituitary apoplexy including hemorrhage into an existing adenoma, and idiopathic intracranial hypertension. A discussion of each entity will focus on the clinical presentation, management and prognosis when necessary and finally, neuroimaging with emphasis on magnetic resonance imaging. The primary purpose of this review is to provide an organized approach to the differential diagnosis and typical imaging patterns for AVSs. We have provided a template for radiologists and specialists to assist in early intervention in order to decrease morbidity and provide value-based patient care through imaging.