"Trapped labelled spins"-related signal on arterial spin labelling in the assessment of flow-diverted aneurysms: preliminary experience.

PURPOSE: To investigate ASL-MRI features of flow-diverted aneurysms, review their haemodynamic surrogates, and discuss their pertinent clinical implications. METHODS: Retrospective single institutional analysis was performed on the clinical and imaging data of patients who underwent digital subtraction angiography (DSA) and ASL-MRI after endovascular flow diversion for cerebral aneurysms. Pseudo-continuous ASL-MRI was performed with post-label delays of 1525-1800 ms. Intra-aneurysmal "trapped labelled spins" (TLS)-related hypersignal, as seen on cerebral blood flow (CBF)-weighted maps of ASL-MRI, was investigated. Intermodality equivalence with DSA [O'Kelly-Marotta (OKM) grading for occlusion], 3D-TOF-MRA, and 3D spin-echo T1-weighted ("black-blood") images was assessed. RESULTS: Ten cases were included. "TLS" signal was demonstrable in 7/8 (87.5%) of the DSA-visible flow-diverted aneurysms (OKM grade B3, n = 6; OKM grade A3, n = 2). No TLS was seen in both OKM-D (excluded) aneurysms. TLS was not visualised in an OKM-B3 aneurysm with < 3 mm opacifying remnant. 3D-TOF-MRA and ASL-MRI were discordant at 5 instances (45.4%; TOF-MRA false negative, n = 4; false positive, n = 1). Loss of flow void on black-blood images corresponded to the absence of TLS and vice versa in all cases but one. CONCLUSION: "Trapped labelled spins"-related signal on ASL-MRI occurs in patent large aneurysms that have undergone successful endovascular flow diversion. This phenomenon likely represents an interplay of a multitude of haemodynamic factors including decelerated intra-aneurysmal inflow and outflow restriction. Serial intra-saccular TLS signal changes may hold diagnostic value, including contexts where 3D-TOF-MRA interpretation becomes dubious. "Trapped labelled spins"-related signal as a non-invasive proxy marker of aneurysm patency can possibly obviate unnecessary DSA.

Mimics of Guillain-Barré Syndrome in Pediatric Patients Admitted to the Neuro-Intensive Care Unit of a Tertiary Care Hospital-A Case Series.

Guillain-Barré syndrome is the most common cause of acute flaccid paralysis in children, but several diseases mimic GBS. We aimed to identify and report the clinical pointers and battery of tests required to differentiate Guillain-Barré syndrome from its observed mimics in the pediatric population admitted to our neuro-critical care unit. We conducted a retrospective record analysis of all pediatric patients admitted over ten years from 2008-2018, whose initial presentation was compatible with a clinical diagnosis of GBS. Eighty-three patients were at first treated as GBS, of which seven (8.4%) were found to have an alternate diagnosis-three cases of paralytic rabies, one case each of acute disseminated encephalomyelitis, cervical myeloradiculopathy, neuromyelitis optica, and a case of community-acquired Staphylococcus aureus pneumonia associated sepsis. Neurophysiological and neuro-virological testing, central nervous system imaging, and sepsis screening helped to confirm the alternate diagnosis. Our case series provides knowledge of subtle clinical differences along with the mindful use of diagnostic testing to facilitate the accurate diagnosis of GBS mimics.

PRESenting a Challenge: Posterior Reversible Encephalopathy Syndrome in Pediatric Patients With Guillain-Barré Syndrome: A Case Series and Review of Literature.

BACKGROUND: Guillain-Barré syndrome (GBS) is an autoimmune disorder characterized by demyelination of peripheral nerves. GBS-associated posterior reversible encephalopathy syndrome (PRES) is a rare and potentially life-threatening complication in the pediatric population. We aimed to report and analyze the clinical features, management, and outcomes of three cases of GBS-associated PRES in our setting in the light of the existing literature. METHODS: Medical records of 75 pediatric patients with GBS were reviewed for autonomic changes and GBS-associated PRES. Thirty-one developed dysautonomia while three were identified to have PRES. Clinical, radiological, laboratory, and treatment data were collected and analyzed. RESULTS: All three patients were male and presented with symptoms of acute flaccid paralysis and respiratory distress requiring mechanical ventilation. All three patients experienced various complications, including hypertension, seizures, and hyponatremia, and were subsequently diagnosed with PRES. Multimodal intensive care resulted in patient improvement and discharge in an ambulatory state after an average of 104 days of care. CONCLUSIONS: GBS-associated PRES is a rare and potentially life-threatening complication that can occur in pediatric patients with GBS. Our findings suggest that early recognition, prompt intervention, and multimodal intensive care can improve patient outcomes. Further studies are needed to determine optimal treatment strategies for GBS-associated PRES.

MRI Spectrum of Toxic Encephalopathy-An Institutional Experience.

Background: There are numerous toxins that affect our nervous system, both central and peripheral. Innumerable differentials exist in patients of acute encephalopathy and the list can be narrowed down with appropriate imaging. Specific neuroradiological features point to a particular diagnosis in a substantial number of cases. Objective: Through this study, we aimed to demonstrate the varied imaging findings of toxic encephalopathy on MRI encountered at our institute. Material and Methods: A retrospective analysis of the patients clinically diagnosed as toxic encephalopathy and referred for imaging between March 2015 and December 2019 was done. A total of 25 patients were included. Patient records were reviewed for clinical details, laboratory investigations, and treatment; the institute Picture Archiving and Communication System provided the imaging findings. Results: Patients presenting were aged between 22 and 55 years (mean-34.3 years). Four patients (16%) presented with imaging findings characteristic of Marchiafava-Bignami disease and six patients (24%) had MRI findings of Wernicke encephalopathy. Three patients (12%) had methanol poisoning sequelae while imaging findings of nitroimidazole drug toxicity were observed in another three patients (12%). Two patients (8%) each of carbon monoxide poisoning and lead toxicity were seen. We had one patient (4%) each of isoniazid, methyl iodide, dextropropoxyphene toxicity, chronic toluene abuse, and hyperglycemia-induced hemiballismus-hemichorea. Conclusion: Our study illustrates the amalgamated spectrum of MRI appearances in various subgroups of toxic encephalopathies. Imaging substantiated by relevant history and clinical manifestations can accurately diagnose the possible causative agent in the majority of the cases.

Dissecting aneurysms of the posterior cerebral artery - A retrospective review of imaging, angiographic characteristics, endovascular management and outcome.

PURPOSE: To review management, clinical and imaging outcomes of dissecting posterior cerebral artery (PCA) aneurysms with emphasis on endovascular management in the form of parent vessel occlusion (PVO) at a tertiary care center. METHODS: Thirty-six dissecting PCA aneurysms (19 ruptured) encountered at our center between January 2013 and November 2019 were reviewed for aneurysm location/size/presence of fetal PCA/management. Postprocedural imaging of patients who underwent endovascular intervention was reviewed for PCA territory infarcts and clinical records assessed for presence of neuro-deficits and outcome. None of the patients underwent a balloon test occlusion (BTO) prior to PVO. RESULTS: The location of the aneurysms was as follows-P1 = 8/P1-P2 = 11/P2 = 5/P2-P3 = 10/P3 = 2. The mean size was 11.7x6.8 mm. Endovascular intervention was carried out in 20 patients in the form of PVO with coiling in 16 patients, coiling alone in 3 patients, and reconstruction of the left PCA with flow diverter deployment in one patient. Postprocedural PCA territory infarct was seen in 5 cases of PVO out of which 4 had a good functional recovery. Overall, 15/16 patients (93.7%) who underwent PVO had mRS ≤ 2 on follow-up. The single case with flow diverter also developed an infarct and had adverse outcome on follow up. CONCLUSION: Among the various management strategies for dissecting PCA aneurysms, PVO is feasible and relatively safe even in absence of BTO in scenarios like critically ill patients with ruptured aneurysms, difficult access and financial constraints. Thromboembolic complications and antiplatelet therapy is a concern in reconstructive strategies.

Imaging findings in intracranial aspergillus infection in immunocompetent patients.

AIM: To study the neuroimaging features of craniocerebral aspergillosis infection in immunocompetent patients. MATERIALS AND METHODS: The clinical and imaging data of 12 patients of aspergillus fungal infection were retrospectively reviewed. Diagnosis of fungal infection was confirmed by histopathologic examination of surgically excised specimen, stereotactic biopsy material, or endoscopic sinus biopsy. The radiologic studies were evaluated for anatomic distribution of lesions, signal intensity, contrast enhancement, presence of hemorrhage, diffusion restriction, perfusion, and spectroscopy characteristics. Medical records, biopsy reports, and autopsy findings were also reviewed. RESULTS: Twelve cases of aspergillosis infections in immunocompetent patients were diagnosed at our hospital over a period of 10 years. Lesions could be classified based on imaging of lesions of sinonasal origin, intracranial mass lesion including both parenchymal or extraparenchymal meningeal based and stroke. Coexisting meningitis was also noted in one patient. Disease of sinonasal origin commonly showed invasion of the cavernous sinus and orbital apex resulting in visual symptoms and multiple cranial nerve palsies. Intracranial mass lesions without sinonasal involvement were seen in five cases that included isolated parenchymal lesion in two patients and dural-based mass lesions in three patients. Isolated intraparenchymal lesions included two cases of fungal cerebritis. Dural-based lesions were large granulomas with a significant mass effect. Infarcts were seen in three patients and angiography showed vessel narrowing or occlusion in all the three patients. CT demonstrated isodense to hyperdense attenuation of primary sinus disease with evidence of bone destruction in all the cases of sinonasal origin. Primary parenchymal lesions showed heterogenous attenuation with predominantly low-density areas. Dural-based lesions showed isodense to hyperdense attenuation. Magnetic resonance imaging revealed isointense to hypointense signal intensity on both T(1)-weighted (T1W) and T(2)-weighted (T2W) images in all lesions of sinonasal origin and isolated dural-based mass lesions. Primary parenchymal lesions showed heterogenous signal intensity pattern with predominantly hypointense signal on T1W and hyperintense signal on T2W images. Diffusion weighted imaging, magnetic resonance spectroscopy, and perfusion-weighted imaging gave valuable ancillary information in these cases. CONCLUSION: Sinonasal disease with intracranial extension is the commonest pattern of aspergillus infection followed by intracranial mass lesions. Hyperdense sinonasal disease with bone destruction and intracranial extension on computed tomography, hypointense signal intensity of the lesions on T2W magnetic resonance images, presence of areas of restricted diffusion, decreased perfusion on perfusion-weighted imaging, and presence of hemorrhages are key to the imaging diagnosis of fungal infection.

Septo-optic dysplasia with encephalocele.

Septo-optic dysplasia is a rare congenital anomaly presenting with visual deficits or pituitary dysfunction. We report the first case of septo-optic dysplasia associated with encephalocele, partial callosal agenesis, polymicrogyria and subcortical nodular heterotopia.