"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.

Persistent Primitive Olfactory Artery: Three Cases.

ABSTRACT: The persistent primitive olfactory artery is a very rare arterial variant with a little over a score of cases reported in literature so far. We present 3 cases illustrating this entity, which were incidentally diagnosed while imaging for other indications.

Pediatric spinal cord infarct: a rare cause of a rare disorder, (wo)man in barrel syndrome.

The "man in barrel syndrome" is a condition which resembles the aspect of patient being constrained in a barrel in which patient presents with bilateral upper limb weakness. It has classically been attributed to supratentorial lesions in watershed zones. We present such a case in a 12-year-old child who presented with bibrachial weakness and was noted to have cervical cord infarct on imaging. Spinal cord infarct is a rare cause of this syndrome, and until now only 20 cases have been described in which cervical cord infarct led to this presentation, all of them being adults. We describe first case report of bibrachial diplegia due to cord infarct in a child. Our case adds to the limited literature of cervical cord ischemia as a cause of "(wo) man in barrel syndrome" and re-iterates the fact that imaging of cervical cord should be considered while evaluating these cases.

Imaging of neurovascular emergencies in pregnancy and puerperium.

Acute neurovascular events, though rare, can complicate pregnancy and postpartum period. It is important to be aware of these clinical conditions for reducing maternal and fetal morbidity and mortality. In this review, we present a few important neurovascular emergencies and their imaging manifestations by various imaging modalities-computed tomography (CT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA)-which presented at our institution in the peripartum period.

Spinal Cord Infarction: Clinical and Radiological Features.

INTRODUCTION: Spinal cord infarction is an uncommon disease varying in its clinical presentation. This study describes the clinical and radiological presentation of spinal cord infarcts in 17 consecutive patients. MATERIAL AND METHODS: Clinical and MR imaging data of 17 patients were reviewed. Inclusion criteria were acute or subacute presentation (peak within 72 hours) and MRI showing typical signal changes on T2WI compatible with spinal cord infarct. Exclusion criteria were clinical or MRI findings suggesting other etiologies. RESULTS: Clinical presentation included dissociative anesthesia, weakness of limbs, back or neck pain, and autonomic symptoms with symptom onset to peak time ranging from few minutes to 48 hours in patients with anterior spinal artery infarct (n = 16), and weakness and sensory loss in ipsilateral upper limb in patient with posterior spinal artery infarct (n = 1). One patient presented with "man-in-the-barrel syndrome (MIB)." MRI findings in anterior spinal artery infarcts included pencillike hyperintensities on T2 sagittal (n = 16, 100%) and "owl eye" appearance on T2 axial (n = 6, 37.5%) images. Diffusion restriction was noted in 8 cases and enhancement was noted in 2 cases. The posterior spinal artery infarct showed T2 hyperintensity in left posterior paramedian triangular distribution in cervical cord (C2-C7). Follow-up was available for 9 patients (period ranging from 15-41 months). Four patients had a favorable outcome who could walk independently, 1 patient could walk with support, and 2 patients were wheelchair bound. Two patients died. CONCLUSION: Spinal cord infarction is a rare but important cause of acute spinal syndrome. Typical distribution and appropriate imaging can help in timely diagnosis.

Aggressive management of vasospasm with direct intra-arterial nimodipine therapy.

BACKGROUND: The conventional medical management of cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH) is associated with uncertainty of outcome and complications. AIMS AND OBJECTIVES: To examine the effect of direct intra-arterial nimodipine therapy on outcome in patients with delayed cerebral ischemia (DCI). SETTINGS AND DESIGN: The retrospective observational study was conducted at a single neurosurgical unit and interventional neuroradiolgy suite of a center managing SAH. MATERIALS AND METHODS: Data analysis of SAH managed surgically during the period from January 2014 through October 2015 was performed. Any decline in the neurological status on clinical examination, such as consciousness, motor and speech deficits, without other identifiable causes such as hydrocephalus, hyponatremia, seizure, intracranial hematoma, or infection, was used to define the presence of DCI. Patients with suspected DCI underwent computed tomography (CT) scan of the head followed by angiography. When vasospasm was detected in the absence of any major arterial territory infarct, the patients were managed with intra-arterial nimodipine therapy. The outcome at discharge was assessed. STATISTICAL ANALYSIS: Mid-P exact, two-tailed P value was used for categorical variables. RESULTS:: A total of 106 patients underwent surgical clipping of an aneurysm following SAH. DCI was diagnosed in 26 (24.5%) patients. Twenty three (88.5%) patients underwent intra-arterial nimodipine therapy. Angiographic response was seen in 22 (95.7%) patients and clinical response in 20 (87%) patients. At discharge, 19 patients (73.1%) with vasospasm had a favorable outcome. There was no significant difference in the outcome of patients with or without vasospasm. CONCLUSIONS: Aggressive management with intra-arterial nimodipine therapy is effective in preventing disability caused by DCI.

Imaging features of rosette-forming glioneuronal tumours (RGNTs): A Series of seven cases.

OBJECTIVE: Rosette-forming glioneuronal tumours (RGNTs) are a recently described, rare, distinct nosological entity of the glioneuronal family. We describe imaging findings (CT and MRI) in seven patients with RGNTs. MATERIALS AND METHODS: This retrospective study includes seven RGNT patients (4 male, 3 female; age range: 7-42 years; mean age: 25 years) diagnosed and treated at our institute. MR studies were performed on 3 T and 1.5-T clinical MR systems. All patients were reviewed by two experienced neuroradiologists and imaging findings were tabulated. RESULTS: Five tumours were located in the posterior fossa, and two were in the pineal region. One of the tumours demonstrated multiple satellite lesions, which involved the midbrain, pons, medulla as well as the cervical cord. Tumours located in the pineal region compressed the 3rd ventricle/aqueduct and extended below the tentorium cerebelli. All the tumours demonstrated enhancement, and susceptibility was evident in six of the seven patients. CSF dissemination was present in two patients. CONCLUSION: RGNTs are usually solid-cystic tumours and frequently demonstrate peripheral/heterogeneous enhancement upon post-contrast study. Haemorrhage is a common feature which may not be evident on CT. Cerebrospinal fluid (CSF) dissemination is a feature and appropriate imaging should be performed whenever an RGNT is suspected. KEY POINTS: CT and MRI findings of seven RGNT cases were retrospectively reviewed. RGNTs are predominantly posterior fossa tumours. RGNTs are typically T1 hypointense and T2 hyperintense. Haemorrhage and peripheral/heterogeneous enhancement are common features of RGNTs. CSF dissemination is a feature of RGNTs and requires appropriate imaging.

Endovascular coil detachment causing EMG artefact in BIS: a mechanistic exploration.

Deployment of endovascular coils used in interventional neuroradiology commonly involves electrolytic detachment of the coil from the pusher catheter. This report describes a case of artefactual increase in electromyography (EMG) values of bispectral index (BIS) monitor during coil detachment. An explanation of this event is provided connecting mechanism of coil detachment and derivation of EMG values in a BIS monitor. While rising EMG values are thought to arise from frontalis contraction, they may as well be an unrecognized electrical artefact, especially in context of undistorted electroencephalography waveform.

Variant course of bilateral anterior cerebral artery in semilobar holoprosencephaly.

We report an unusual case of semilobar holoprosencephaly with variant course of bilateral anterior cerebral arteries (ACA) in a 1-year-old child. This is a very rare arterial variant, given that holoprosencephalic brains are usually associated with azygous ACAs.

Profile of patients with craniovertebral junction anomalies with posterior circulation strokes.

BACKGROUND: Craniovertebral junction (CVJ) anomalies are rare and treatable risk factors for posterior circulation strokes (PCSs). Most of the literature comprises case reports and from varied specialities. METHODS: Chart review of patients with PCS with CVJ anomalies admitted in a single tertiary stroke care unit. We describe their clinical profile, investigative findings, and therapeutic outcomes. RESULTS: We saw 7 patients (6 males, mean age 20.1 ± 12.0 years), all previously undiagnosed during the 6-year period. Three patients had a combination of atlantoaxial dislocation (AAD), basilar invagination (BI) and Klippel-Feil anomalies, 2 patients had os odontoideum with AAD, and 1 patient each had isolated AAD and BI. Clinically, they presented with first or recurrent episodes of stroke with neck pain. Examination revealed noticeable skeletal markers and neurologic deficits involving the arterial territory. Routine stroke risk factors were absent. X-ray of CVJ was abnormal and diagnostic in all the patients. Other imaging modalities had their own contributions for identifying associated defects, demonstrating pathophysiology, and management of these patients. Acute care with anticoagulation and supportive measures helped in recovery of all of them. Posterior fusion was done in 4 patients, and 2 patients are awaiting the surgery. During follow-up all patients have improved and none had recurrences. CONCLUSIONS: In case of a young patient with PCS (first/recurrent) in the absence of routine risk factors for stroke, careful physical examination and imaging with basic X-ray may help in the diagnosis CVJ abnormalities, which may be effectively managed by a multidisciplinary team to prevent recurrences.

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.

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.

Comparison of arterial spin labeling perfusion with dynamic susceptibility contrast perfusion in Moyamoya disease.

Objectives: Moyamoya disease (MMD) leads to frequent ischemic/hemorrhagic manifestations. Our aim was to compare findings of arterial spin labeling (ASL) with dynamic susceptibility contrast (DSC) perfusion in patients of MMD. Materials and Methods: Patients diagnosed as MMD underwent magnetic resonance imaging with ASL and DSC perfusion sequences. Perfusion in bilateral anterior cerebral artery and middle cerebral artery territories at two levels (level of thalami and centrum semiovale) was graded as normal (score 1), or reduced (score 2) on DSC and ASL cerebral blood flow (CBF) maps by comparison with normal cerebellar perfusion. Time to peak (TTP) maps of DSC perfusion were also qualitatively scored as normal (score 1), or increased (score 2) similarly. Correlation between scores of ASL, CBF, DSC, CBF, and DSC, TTP maps was assessed by using Spearman's rank correlation. Results: Among the 34 patients, we did not find any significant correlation between the ASL CBF maps and DSC CBF maps (r = -0.028, P = 0.878), mean matching index 0.39 ± 0.31, whereas significant correlation was noted between the ASL CBF maps and DSC TTP maps (r = 0.58, P = 0.0003), mean matching index 0.79 ± 0.26. ASL CBF underestimated the perfusion compared to DSC perfusion. Conclusion: ASL perfusion CBF maps do not match the DSC perfusion CBF maps and rather match the TTP maps of DSC perfusion. This is explained by inherent problems in estimation of CBF in these techniques because of delay in arrival of label (in ASL perfusion) or contrast bolus (in DSC perfusion) due to the presence of stenotic lesions.

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.

Subacute Sclerosing Panencephalitis: Restricted Diffusion and Clinical Evolution.

Background: Subacute sclerosing panencephalitis (SSPE) is a rare entity characterized by a protracted course and progressive neurological deterioration. Objective: We present patterns of diffusion restriction in eight cases of SSPE, a seldom described imaging attribute. Methods: A retrospective analysis was performed on the clinical and neuroimaging data obtained from records of patients with proven SSPE. Patients whose magnetic resonance imaging (MRI) showed evidence of diffusion restriction were included in the analysis. MRI was performed on 3 T and 1.5-T clinical MR systems. Imaging characteristics were reviewed and tabulated by two neuroradiologists. Results: Eight SSPE patients (seven men, one woman; age range: 5-15 years; mean age: 11 years) diagnosed and managed at our institute were included in the analysis. Restricted diffusion was evident in the basal ganglia (n = 3), corpus callosum (n = 2), white matter (n = 2) and in bilateral middle cerebellar peduncles (MCP) (n = 2). One patient had diffusion restriction in the genu of the corpus callosum and bilateral frontal cortical white matter. None of the diffusion-restricted lesions showed contrast enhancement or susceptibility. Six cases fulfilled the diagnostic criteria for fulminant SSPE (fSSPE). The extent of neuroparenchymal involvement was greater in this subset of patients. Conclusions: Restricted diffusion in SSPE, hitherto infrequently described, can indeed occur in both grey and white matter structures and in both supratentorial and infratentorial compartments. Parenchymal diffusion restriction in SSPE possibly reflects an early time point in the clinical evolution. A greater extent of parenchymal diffusion restriction may portend a rapid downhill course, possibly qualifying for fSSPE.

Abusive head trauma in India: imaging raises the curtain.

The purpose of the study was to identify children at our institute who possibly suffered abusive head trauma (AHT). A retrospective study of CT imaging of children between one month to three years of age between January 2013 and May 2021 was carried out at a dedicated neurocentre in Southern India. We identified 48 cases of possible AHT. The demographics, clinical features at presentation, imaging and fundus findings were analyzed. Imaging revealed subdural hemorrhage (SDH) in 42 and sub dural effusion (SDE) in 5 cases, one case had only hypoxia. The location of SDH was studied as was hypoxia underlying SDH, global hypoxia and ischemia. Cases of subarachnoid hemorrhage (SAH), parenchymal hematoma & intraventricular hemorrhage (IVH) were also noted. Skeletal survey, chest X-ray and CT spine were reviewed. AHT needs to be paid attention to in the Indian scenario. An extensive work up is required to substantiate the claim and to work on prevention & management of these cases subsequently.

Adult onset moyamoya disease: institutional experience.

Moyamoya disease is a progressive steno-occlusive disease of bilateral carotid forks with the formation of fine collateral vascular network and is an angiographic diagnosis. We analyzed case records of 11 patients with "adult-onset moyamoya disease." Six patients presented with intracranial hemorrhage (intracerebral and/or intraventricular) and 5 with focal ischemia. Angiography revealed bilateral Internal carotid artery involvement in 8 patients and unilateral involvement in 3. Posterior cerebral artery involvement was seen in 3 patients. Saccular aneurysm involving posterior circulation was seen in only 1 patient. Although rare, adult-onset moyamoya disease should be considered as one of the causes for intracerebral and intraventricular hemorrhage in adults.

Anterior Cranial Fossa Dural Arteriovenous Fistulae - Angioarchitecture and Intervention.

PURPOSE: Anterior cranial fossa (ACF) dural arteriovenous fistulae (DAVF) are rare, unique, and ominous. While surgical disconnection is considered as the favored management option, endovascular treatment has lately gained importance. We present a single institution experience of seven cases. METHOD: A retrospective analysis was performed on the institutional patient database. Features analyzed were demographic details, symptoms, angioarchitecture, treatment course, angiographic results, procedural complications, and follow-up. RESULTS: This study included seven patients. The age at presentation ranged from 5-67 years. Clinical symptomatology was as intracranial hemorrhage in 4 patients and headache, chemosis and seizures in one patient each. The fistulae were paramedian at the ACF base. All DAVFs were Cognard type 4. The arterial feeders were from the anterior ethmoidal branches of the ophthalmic artery in all cases (bilateral in n = 5), frontal branches of the middle meningeal artery (MMA) (n = 6), and multiple ECA branches. The arterial route was the choice for access. Complete fistula obliteration was achieved in all but one patient. A traversed vein underwent rupture in one patient. One patient suffered postsurgical hemorrhage. No clinical or angiographic recurrence was noted. CONCLUSION: The DAVFs of the ACF are inherently high-grade lesions. Transorbital ECA-ICA branch anastomoses may be recruited as feeders. They may be best managed by multidisciplinary means personalized on an angioarchitectural basis. Endovascular embolization is safe and efficacious when performed through a navigable feeder from the frontal division of the MMA, which according to our interpretation is in anastomosis with the anterior falcine branch of the anterior ethmoidal artery.