Optic Neuropathy Due to Compression by an Ectatic Internal Carotid Artery Within the Orbital Apex.

ABSTRACT: Neurovascular compression is a rare but potentially treatable cause of optic neuropathy. Although incidental contact of the cisternal optic nerve and internal carotid artery (ICA) is common, compressive optic neuropathy occurring within the orbital apex has not been comprehensively described. We report a case of intra-orbital and intracanalicular optic nerve compression due to an ectatic ICA in a patient with congenital absence of the contralateral ICA. This report describes the complementary roles of advanced neuroimaging and neuro-ophthalmologic examination in rendering the diagnosis.

Prevalence and significance of cranial nerve imaging abnormalities in patients with hereditary neuropathies: Clinical implications at the skull base.

OBJECTIVE: To estimate the prevalence and significance of cranial nerve (CN) imaging abnormalities in patients with hereditary neuropathy and discuss clinical implications. METHODS: We retrospectively analyzed data from patients at four tertiary academic medical centers with hereditary neuropathy diagnoses who had undergone gadolinium-enhanced magnetic resonance imaging (MRI) of the brain or skull base between 2004 and 2018. MRI scans, as well as computed tomography imaging when available, were reviewed and bivariable analysis was performed to identify predictors of CN abnormalities on imaging. RESULTS: Among 39 patients meeting study criteria, 11 had clinical CN deficits (28%) and 8 had CN abnormalities on imaging (21%). Of the patients with CN abnormalities on imaging, half had CN deficits (4/8) and only a quarter had imaging abnormalities of the CNs with the deficits (2/8). Imaging abnormalities were found in varied CNs, including CNs III, V, VII, and the VII/VIII complex in the internal auditory canal. MRI obtained for the purpose of evaluating CN deficits had a statistically significant increased likelihood of containing CN imaging abnormalities. However, CN deficits themselves were not predictive of imaging abnormalities. CONCLUSION: Thickening and enhancement of CNs on MRI may be found in approximately 1/5 of patients with hereditary neuropathies and are inconsistently associated with clinical deficits. These imaging findings should not be mistaken for neoplastic and infectious processes as they may be manifestations of the patients' underlying genetic neuropathy. LEVEL OF EVIDENCE: 4.

CerebroVis: Designing an Abstract yet Spatially Contextualized Cerebral Artery Network Visualization.

Blood circulation in the human brain is supplied through a network of cerebral arteries. If a clinician suspects a patient has a stroke or other cerebrovascular condition, they order imaging tests. Neuroradiologists visually search the resulting scans for abnormalities. Their visual search tasks correspond to the abstract network analysis tasks of browsing and path following. To assist neuroradiologists in identifying cerebral artery abnormalities, we designed CerebroVis, a novel abstract-yet spatially contextualized-cerebral artery network visualization. In this design study, we contribute a novel framing and definition of the cerebral artery system in terms of network theory and characterize neuroradiologist domain goals as abstract visualization and network analysis tasks. Through an iterative, user-centered design process we developed an abstract network layout technique which incorporates cerebral artery spatial context. The abstract visualization enables increased domain task performance over 3D geometry representations, while including spatial context helps preserve the user's mental map of the underlying geometry. We provide open source implementations of our network layout technique and prototype cerebral artery visualization tool. We demonstrate the robustness of our technique by successfully laying out 61 open source brain scans. We evaluate the effectiveness of our layout through a mixed methods study with three neuroradiologists. In a formative controlled experiment our study participants used CerebroVis and a conventional 3D visualization to examine real cerebral artery imaging data to identify a simulated intracranial artery stenosis. Participants were more accurate at identifying stenoses using CerebroVis (absolute risk difference 13%). A free copy of this paper, the evaluation stimuli and data, and source code are available at osf.io/e5sxt.

Natural history of cranial fibrous dysplasia revealed during long-term follow-up: Case report and literature review.

BACKGROUND: Fibrous dysplasia (FD) is a rare developmental disease characterized by the replacement of bone marrow with proliferating fibro-osseous tissue. There exist three forms of FD-monostotic, polyostotic, and that associated with McCune-Albright syndrome. The disease can present in different locations and with a variety of symptoms. One of the more common locations of FD occurrence is the craniofacial region. Treatment of asymptomatic FD often involves conservative management with serial imaging. Medical management with bisphosphonates is an option, though long-term efficacy data are lacking. Surgical resection is usually reserved for very large or symptomatic lesions. CASE DESCRIPTION: We discuss the most unusual case of a 52-year-old male found to have a left pterional mass while being worked up for sinus headaches. The patient elected to follow this lesion conservatively, and imaging several years later showed obvious growth which accelerated in the last 4 years during an 18-year observational period. He ultimately underwent successful resection of an extradural and intradural FD. CONCLUSIONS: The significant growth potential of these lesions was revealed in this patient, in whom conservative management had been adopted. Despite optimal surgical resection and outcome in this case, the importance of surveillance imaging and perhaps earlier intervention cannot be underestimated when managing cranial FD.

Pathophysiologic differences in cerebral autoregulation after subarachnoid hemorrhage.

OBJECTIVE: To understand the physiologic basis of impaired cerebral autoregulation in subarachnoid hemorrhage (SAH) and its relationship to neurologic outcomes. METHODS: The cohort included 121 patients with nontraumatic SAH admitted to a neurointensive critical care unit from March 2010 to May 2015. Vasospasm was ascertained from digital subtraction angiography and delayed cerebral ischemia (DCI) was defined as new cerebral infarction on high-resolution CT. Cerebral blood flow and beat-by-beat pressure were recorded daily on days 2-4 after admission. Autoregulatory capacity was quantified from pressure flow relation via projection pursuit regression. The main outcome was early alterations in autoregulatory mechanisms as they relate to vasospasm and DCI. RESULTS: Forty-three patients developed only vasospasm, 9 only DCI, and 14 both. Autoregulatory capacity correctly predicted DCI in 86% of training cohort patients, generalizing to 80% of the patients who were not included in the original model. Patients who developed DCI had a distinct autoregulatory profile compared to patients who did not develop secondary complications or those who developed only vasospasm. The rate of decrease in flow was significantly steeper in response to transient reductions in pressure. The rate of increase in flow was markedly lower, suggesting a diminished ability to increase flow despite transient increases in pressure. CONCLUSIONS: The extent and nature of impairment in autoregulation accurately predicts neurologic complications on an individual patient level, and suggests potentially differential impairments in underlying physiologic mechanisms. A better understanding of these can lead to targeted interventions to mitigate neurologic morbidity.

Anatomic Eponyms in Neuroradiology: Brain, Cerebral Vasculature, and Calvarium.

Medical eponyms are ubiquitous, numerous, and at times controversial. They are often useful for succinctly conveying complex concepts, and familiarity with eponyms is important for proper usage and appropriate communication. In this historical review, we identify 18 anatomic eponyms used to describe structures of the brain, cerebral vasculature, and calvarium. For each structure, we first offer a biographical sketch of the individual for whom the structure is named. This is followed by a description of the anatomic structure and a brief discussion of its clinical relevance.

The frequency and severity of intracranial hypotension post-intraoperative lumbar drainage using a Tuohy needle and the traditional needle.

Background Intraoperative lumbar cerebrospinal fluid (CSF) drainage is a well-recognised technique in cranial and vascular surgery. The goal of the study was to assess the frequency and severity of intracranial hypotension post-intraoperative lumbar drainage performed using two different techniques, a 14G Tuohy needle versus an 18G traditional needle. Methods The medical records and imaging studies of 94 patients who had undergone open cranial operation were retrospectively studied: 47 patients had intraoperative lumbar drainage and 47 patients did not. A 14G Tuohy needle was employed in 27 (57.4%) patients and an 18G traditional needle was employed in 20 (42.6%) patients. Results There were signs of intracranial hypotension on MR images in nine (19.1%) patients who had intraoperative lumbar CSF drainage; none of the patients in the control group exhibited the MR signs of intracranial hypotension. A 14G needle was used in 6/9 patients and resulted in severe complications: one patient developed a delayed intracranial epidural hematoma that required emergency evacuation and a blood patch. Another patient developed somnolence that required two epidural blood patches and a third patient had protracted headaches. The 18G needle was used in the remaining 3/9 patients who were asymptomatic or presented with mild headaches. Conclusion The use of the smaller 18G traditional needle was associated with better outcomes with regards to intracranial hypotension, and the frequency of severe complications was higher with the use of the 14G Tuohy needle.

Intrasellar abscess following pituitary surgery.

PURPOSE: Intrasellar abscess is an uncommon cause of mass lesions in the sella turcica. Few cases have been reported in the literature, and much remains unknown about the etiology and diagnosis of these lesions. We sought to review a series of patients with intrasellar abscess encountered at our institution and identify defining characteristics of their presentation and management. METHODS: We conducted a retrospective chart review for intrasellar infection cases associated with a mass lesion. Included cases had clear demonstration of a mass lesion on imaging with subsequent positive microbiological cultures. Clinical presentation, management, post-operative course, neuroimaging, microbiology, and any perturbations in serum pituitary biochemical markers were examined. RESULTS: All examined patients had a history of antecedent transsphenoidal pituitary surgery within the preceding 10 months. All presented with headaches, three with progressive visual loss, one with meningismus, one with fever in the setting of an active cerebrospinal fluid leak, and one with fever, meningismus, hypotension, and progressive somnolence. No patient presented with acute endocrine abnormalities. A majority did not initially have any diffusion restriction present on MRI, but in one case we were able to track the evolution of diffusion restriction over sequential MRI scans. Two patients had complete resolution of presenting symptoms, while three experienced improvement or stabilization of their neurologic deficit. There were no mortalities. CONCLUSIONS: Pituitary abscess remains a rare diagnosis that can be difficult to make and to confirm. In our series we found a strong association between culture-positive abscess and recent pituitary surgery. When present, prompt treatment with surgical drainage and aggressive post-operative antibiotics can lead to a favorable outcome.

Comparison of seeding methods for visualization of the corticospinal tracts using single tensor tractography.

OBJECTIVES: To compare five different seeding methods to delineate hand, foot, and lip components of the corticospinal tract (CST) using single tensor tractography. METHODS: We studied five healthy subjects and 10 brain tumor patients. For each subject, we used five different seeding methods, from (1) cerebral peduncle (CP), (2) posterior limb of the internal capsule (PLIC), (3) white matter subjacent to functional MRI activations (fMRI), (4) whole brain and then selecting the fibers that pass through both fMRI and CP (WBF-CP), and (5) whole brain and then selecting the fibers that pass through both fMRI and PLIC (WBF-PLIC). Two blinded neuroradiologists rated delineations as anatomically successful or unsuccessful tractography. The proportions of successful trials from different methods were compared by Fisher's exact test. RESULTS: To delineate hand motor tract, seeding through fMRI activation areas was more effective than through CP (p<0.01), but not significantly different from PLIC (p>0.1). WBF-CP delineated hand motor tracts in a larger proportion of trials than CP alone (p<0.05). Similarly, WBF-PLIC depicted hand motor tracts in a larger proportion of trials than PLIC alone (p<0.01). Foot motor tracts were delineated in all trials by either PLIC or whole brain seeding (WBF-CP and WBF-PLIC). Seeding from CP or fMRI activation resulted in foot motor tract visualization in 87% of the trials (95% confidence interval: 60-98%). The lip motor tracts were delineated only by WBF-PLIC and in 36% of trials (95% confidence interval: 11-69%). CONCLUSIONS: Whole brain seeding and then selecting the tracts that pass through two anatomically relevant ROIs can delineate more plausible hand and lip motor tracts than seeding from a single ROI. Foot motor tracts can be successfully delineated regardless of the seeding method used.

Impaired cerebral autoregulation is associated with vasospasm and delayed cerebral ischemia in subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Cerebral autoregulation may be impaired in the early days after subarachnoid hemorrhage (SAH). The purpose of this study was to examine the relationship between cerebral autoregulation and angiographic vasospasm (aVSP) and radiographic delayed cerebral ischemia (DCI) in patients with SAH. METHODS: Sixty-eight patients (54±13 years) with a diagnosis of nontraumatic SAH were studied. Dynamic cerebral autoregulation was assessed using transfer function analysis (phase and gain) of the spontaneous blood pressure and blood flow velocity oscillations on days 2 to 4 post-SAH. aVSP was diagnosed using a 4-vessel conventional angiogram. DCI was diagnosed from CT. Decision tree models were used to identify optimal cut-off points for clinical and physiological predictors of aVSP and DCI. Multivariate logistic regression models were used to develop and validate a risk scoring tool for each outcome. RESULTS: Sixty-two percent of patients developed aVSP, and 19% developed DCI. Patients with aVSP had higher transfer function gain (1.06±0.33 versus 0.89±0.30; P=0.04) and patients with DCI had lower transfer function phase (17.5±39.6 versus 38.3±18.2; P=0.03) compared with those who did not develop either. Multivariable scoring tools using transfer function gain>0.98 and phase<12.5 were strongly predictive of aVSP (92% positive predictive value; 77% negative predictive value; area under the receiver operating characteristic curve, 0.92) and DCI (80% positive predictive value; 91% negative predictive value; area under the curve, 0.94), respectively. CONCLUSIONS: Dynamic cerebral autoregulation is impaired in the early days after SAH. Including autoregulation as part of the initial clinical and radiographic assessment may enhance our ability to identify patients at a high risk for developing secondary complications after SAH.

Magnetic resonance imaging validation of pituitary gland compression and distortion by typical sellar pathology.

OBJECT: Identification of the normal pituitary gland is an important component of presurgical planning, defining many aspects of the surgical approach and facilitating normal gland preservation. Magnetic resonance imaging is a proven imaging modality for optimal soft-tissue contrast discrimination in the brain. This study is designed to validate the accuracy of localization of the normal pituitary gland with MRI in a cohort of surgical patients with pituitary mass lesions, and to evaluate for correlation between presurgical pituitary hormone values and pituitary gland characteristics on neuroimaging. METHODS: Fifty-eight consecutive patients with pituitary mass lesions were included in the study. Anterior pituitary hormone levels were measured preoperatively in all patients. Video recordings from the endoscopic or microscopic surgical procedures were available for evaluation in 47 cases. Intraoperative identification of the normal gland was possible in 43 of 58 cases. Retrospective MR images were reviewed in a blinded fashion for the 43 cases, emphasizing the position of the normal gland and the extent of compression and displacement by the lesion. RESULTS: There was excellent agreement between imaging and surgery in 84% of the cases for normal gland localization, and in 70% for compression or noncompression of the normal gland. There was no consistent correlation between preoperative pituitary dysfunction and pituitary gland localization on imaging, gland identification during surgery, or pituitary gland compression. CONCLUSIONS: Magnetic resonance imaging proved to be accurate in identifying the normal gland in patients with pituitary mass lesions, and was useful for preoperative surgical planning.

The utility of conductive plastic electrodes in prolonged ICU EEG monitoring.

We investigated the feasibility and utilization of conductive plastic electrodes (CPEs) in patients undergoing continuous video-electroencephalographic (EEG) monitoring in the intensive care unit (ICU), and assessed the quality of brain magnetic resonance imaging (MRI) and computed tomography (CT) images obtained during this period. A total of 54 patients were monitored. Seizures were recorded in 16 patients. Twenty-five patients had neuroimaging performed with electrodes in place; 15 MRI and 23 CT scans were performed. All patients had excellent quality anatomical images without clinically significant artifacts, and without any signs or symptoms that raised safety concerns. Recording quality of the EEG was indistinguishable to that achieved with standard gold electrodes. The use of CPEs allowed for uninterrupted EEG recording of patients who required urgent neuroimaging, and decreased the amount of time spent by the technologists required to remove and reattach leads.

Methylmalonic acidemia: brain imaging findings in 52 children and a review of the literature.

BACKGROUND: Methylmalonic acidemia (MMA) is an autosomal-recessive inborn error of metabolism. OBJECTIVE: To recognize the CT and MR brain sectional imaging findings in children with MMA. MATERIALS AND METHODS: Brain imaging studies (47 MR and 5 CT studies) from 52 children were reviewed and reported by a neuroradiologist. The clinical data were collected for each patient. RESULTS: The most common findings were ventricular dilation (17 studies), cortical atrophy (15), periventricular white matter abnormality (12), thinning of the corpus callosum (8), subcortical white matter abnormality (6), cerebellar atrophy (4), basal ganglionic calcification (3), and myelination delay (3). The brain images in 14 patients were normal. CONCLUSION: Radiological findings of MMA are nonspecific. A constellation of common clinical and radiological findings should raise the suspicion of MMA.

Multidetector CT of the paranasal sinus: potential for radiation dose reduction.

The aim of the study was to retrospectively determine the potential for radiation dose reduction at multidetector computed tomography (CT) of the paranasal sinus by using computer simulation of the effect of low-radiation dose acquisition on diagnostic image quality. This HIPAA compliant study was approved by the institutional human research committee. The need for informed patient consent was waived. Twenty patients underwent four-section CT at 120 kV, 170 mAs, and 4 x 1-mm collimation. Artificial image noise was added to the CT raw data by using a dedicated software platform. Acquisitions with effective tube currents of 134, 100, 67, and 33 mAs were simulated. Each raw data set was reconstructed with bone and soft-tissue algorithms, and two radiologists independently rated the images in blinded fashion. A two-sided paired Student t test was used for statistical analysis. The lowest radiation dose that still provided diagnostic quality was