Lumbar vertebral diskitis-osteomyelitis with mycotic abdominal aortic aneurysm caused by Streptococcus mitis

Vertebral osteomyelitis is a well-documented disease entity in literature with various known etiologies. However, vertebral diskitis-osteomyelitis secondary to an infected aortic aneurysm is an uncommon and life-threatening complication. We present the case of a 65-year-old male patient who presented with chronic low back pain that acutely worsened for 1 to 1.5 months and was diagnosed with vertebral diskitis-osteomyelitis secondary to a contiguous infection from an adjacent mycotic aortic aneurysm. To our knowledge, this is one of the few cases reported of vertebral diskitis-osteomyelitis secondary to mycotic aortic aneurysm. We discuss the findings on CT and MRI, as well as the value of imaging in guiding management.

CT perfusion in stroke: Comparing conventional and RAPID automated software

CT perfusion (CTP) imaging is increasingly used for routine evaluation of acute ischemic stroke. Knowledge about the different types of CTP software, imaging acquisition and post-processing, and interpretation is crucial for appropriate patient selection for reperfusion therapy. Conventional vendor-provided CTP software differentiates between ischemic penumbra and core infarct using the tiebreaker of critically reduced cerebral blood volume (CBV) values within brain regions showing abnormally elevated time parameters like mean transit time (MTT) or time to peak (TTP). On the other hand, RAPID automated software differentiates between ischemic penumbra and core infarct using the tiebreaker of critically reduced cerebral blood flow (CBF) values within brain regions showing abnormally elevated time to maximum (Tmax). Additionally, RAPID calculates certain indices that confer prognostic value, such as the hypoperfusion and CBV index. In this review, we aim to familiarize the reader with the technical principles of CTP imaging, compare CTP maps generated by conventional and RAPID software, and discuss important thresholds for reperfusion and prognostic indices. Lastly, we discuss common pitfalls to help with the accurate interpretation of CTP imaging.

Corneal immune cells as a biomarker of inflammation in multiple sclerosis: a longitudinal study

Background

Corneal immune cells (ICs) are antigen-presenting cells that are known to increase ocular and systemic inflammatory conditions.

Objective

We aimed to assess longitudinal changes in corneal IC in patients with multiple sclerosis (MS) and relation to disability and ongoing treatment.

Design

Prospective observational study conducted between September 2016 and February 2020.

Methods

Patients with relapsing-remitting MS (RRMS) (n = 45) or secondary progressive MS (SPMS) (n = 15) underwent corneal confocal microscopy (CCM) at baseline and 2-year follow-up for estimation of corneal IC density [dendritic cells with (DCF) (cells/mm2) or without nerve fiber contact (DCP); and non-dendritic cells with (NCF) or without nerve fiber contact (NCP)]. Optical coherence tomography, neuroimaging, and disability assessments were additionally performed. Healthy controls (n = 20) were assessed at baseline.

Results

In both RRMS and SPMS compared to controls, DCP (p < 0.001 and p < 0.001, respectively) and DCF (p < 0.001 and p = 0.005) were higher and NCF (p = 0.007 and p = 0.02) was lower at baseline. DCP showed excellent performance in identifying patients with MS (sensitivity/specificity = 0.88/0.90) followed by DCF (0.80/0.75) and NCF (0.80/0.85). At follow-up compared to baseline, DCP (p = 0.01) was significantly reduced, and NCP (p = 0.004) and NCF (p = 0.04) were increased. Subgroup analysis showed that baseline NCP and NCF were significantly higher (p = 0.04-0.05) in patients who switched disease-modifying treatment, and baseline NCP (p = 0.05) was higher in patients on interferon.

Conclusion

Baseline and change in corneal IC were related to axonal degeneration and treatment status. Evaluation of corneal IC using CCM may allow an assessment of ongoing inflammation, disease progression, and the effect of treatment in MS.

Ischemia of the parotid gland and adjacent muscles of mastication following middle meningeal artery embolization

Middle meningeal artery (MMA) embolization is commonly performed as either a first-line or adjunct treatment for chronic subdural hematomas (cSDH). We present the case of a 59 year-old male patient who presented with right hemibody weakness and cognitive impairment and was diagnosed with left-sided cSDH. A left MMA embolization was performed due to the recurrent nature of the chronic subdural hemorrhage and the history of prior craniotomy. On postoperative day 1, the patient developed sudden onset left facial swelling and tenderness, and a contrast computed tomography (CT) of the neck revealed acute ischemia in the left parotid gland, adjacent superior aspect of the left masseter muscle, the left lateral pterygoid, and left temporalis muscles. The patient was treated conservatively with antibiotics, steroids, and analgesics and reported resolution of symptoms on the three-month follow-up. To our knowledge, this is the first reported case of the ipsilateral parotid gland, temporalis muscle, adjacent superior aspect of the masseter muscle, and pterygoid muscle ischemia secondary to non-target particle embolization following MMA embolization in cSDH. Knowledge of normal and variant origin of the MMA and various anastomoses of this vessel with branches of the internal carotid artery (ICA), external carotid artery (ECA), and vertebrobasilar system is crucial to avoid complications during embolization.

Practical microscopic neuroanatomy of the limbic system and basal forebrain identifiable on clinical 3T MRI

Microscopic neuroanatomy of limbic system and basal forebrain on MRI is complex and is a terra incognita for many radiologists, clinicians, and neuroscientists. Interestingly, most of the important structures/at least anatomical regions containing these structures demonstrable on cadaveric and surgical dissections can be identified on clinical MRI, with 3T being much better than 1.5T. This article teaches the practical MRI identification of these structures which will greatly help in evaluating complex ailments like temporal lobe epilepsy, Alzheimer dementia, and other neuropsychiatric disorders. This knowledge will also aid in accurate reporting of tumor spread along the white matter fasciculi in the temporal stem/basal forebrain region. Limbic system includes the mesial temporal structures and their connections, piriform cortex including "area tempestas," and the septal area comprising of subcallosal area and paraterminal gyrus. Basal forebrain includes structures like substantia innominata with basal nucleus of Meynert, diagonal gyrus/diagonal band of Broca, and nucleus accumbens lying in between the anterior perforated substance inferiorly and the anterior commissure superiorly.

Cerebellar, hippocampal, and basal nuclei transient edema with restricted diffusion (CHANTER) syndrome in the setting of opioid and phencyclidine use

Cerebellar, hippocampal, and basal nuclei transient edema with restricted diffusion (CHANTER) syndrome is a constellation of specific imaging findings characterized by cytotoxic edema in the bilateral hippocampi, cerebellar cortices, and basal ganglia in patients presenting with altered mental status in the setting of substance intoxication. Previous case reports have demonstrated a strong correlation between CHANTER syndrome and polysubstance abuse, particularly with opioid intoxication. The patient we present in this case was found unresponsive following opioid use and demonstrated a constellation of findings on initial and follow-up imaging, consistent with CHANTER syndrome. While cases of irreversible brain damage or death during hospitalization have been reported in the literature, our patient demonstrated near-full recovery a few days after admission to the hospital. We aim to highlight the presentation and progression of CHANTER syndrome and alert clinicians and radiologists to include this entity in their diagnostic checklist for patients with polysubstance abuse and altered mental status.

Synchronous Ectopic Thyroid Gland and Ectopic Parathyroid Adenoma on 99mTc-Sestamibi Scintigraphy and Correlative Imaging

99mTc-sestamibi scintigraphy localizes parathyroid adenoma as a persistent focus of uptake on delayed images, whereas thyroid glands in normal or ectopic locations are seen on only early images and wash out on delayed images. We report a case of absence of eutopic neck thyroid activity and synchronous ectopic lingual thyroid and mediastinal parathyroid adenoma on scintigraphy confirmed with CT.

Recurrent sporadic malignant triton tumor in the carotid sheath in the absence of neurofibromatosis

Malignant Triton Tumors (MTTs) are a rare and aggressive subtype of malignant peripheral nerve sheath tumors (MPNSTs), often associated with neurofibromatosis type 1. This case report describes a unique instance of recurrent sporadic MTT within the carotid sheath in a 33-year-old male without any personal or familial history of neurofibromatosis. The patient initially presented with a biopsy-confirmed MTT in the right neck, involving the carotid body and brachial plexus, and underwent partial resection, radiation therapy, and chemotherapy. Six months later, the patient presented with recurrent MTT, and subsequently underwent radical tumor resection, segmental right carotid artery resection, and deep femoral vein interposition. Recovery was complicated by hematoma formation, and the patient developed vocal fold paralysis and a left vocal fold cyst, necessitating further surgeries. Yearly follow-ups for 8 years revealed no recurrence. This case emphasizes the importance of comprehensive patient evaluation, including clinical history, imaging, and biopsy findings, for accurate diagnosis and prompt surgical intervention in managing such rare and aggressive tumors. Further research is needed to identify novel therapies and improve survival rates for patients with MTTs.

Injury to the circuit of Papez: An overlooked cause of recurrent seizures

KEY CLINICAL MESSAGE

Papez' circuit is a unique neural pathway in the limbic system that is correlated with seizure activity. Injuries affecting Papez' circuit are often small and unusual in location but can be identifiable in MRI and functional imaging modalities, which can be helpful in the workup of refractory epilepsy.

ABSTRACT

The Papez circuit is a unique neural pathway in the limbic system of the brain. We review a patient presenting with recurrent seizures as the main manifestation of Papez' circuit pathology. The radiologic features of ischemia involving the mammillothalamic tract in Papez' circuit were correlated with the seizure activity.

MR imaging differentiating features between lytic and degenerative lumbosacral spondylolisthesis

Spondylolisthesis is characterized by the displacement of one vertebral body in relation to the adjacent vertebra. It is commonly observed in the lower lumbar region and can be caused by a variety of factors, including spondylolysis (a fracture in the pars interarticularis) or degenerative disease. Magnetic resonance imaging (MRI) is becoming increasingly popular as the primary modality for evaluation of low back pain and is often used in the absence of radiographs or Computed Tomography. However, it can be challenging for radiologists to differentiate between the two types of spondylolisthesis based on MRI alone. The goal of this article is to identify key imaging features on MRI that can aid radiologists in differentiating between spondylolysis and degenerative spondylolisthesis on MRI. Five key concepts are discussed: the "step-off" sign, the "wide canal" sign, T2 cortical bone signal on MRI, epidural fat interposition, and fluid in the facet joints. The utility, limitations and potential pitfalls of these concepts are also discussed to provide a comprehensive understanding of their use in differentiating between the two types of spondylolisthesis on MRI.

Corneal axonal loss as an imaging biomarker of neurodegeneration in multiple sclerosis: a longitudinal study

Background

Resourceful endpoints of axonal loss are needed to predict the course of multiple sclerosis (MS). Corneal confocal microscopy (CCM) can detect axonal loss in patients with clinically isolated syndrome and established MS, which relates to neurological disability.

Objective

To assess corneal axonal loss over time in relation to retinal atrophy, and neurological and radiological abnormalities in MS.

Methods

Patients with relapsing-remitting (RRMS) (n = 68) or secondary progressive MS (SPMS) (n = 15) underwent CCM and optical coherence tomography. Corneal nerve fibre density (CNFD-fibres/mm²), corneal nerve branch density (CNBD-branches/mm²), corneal nerve fibre length (CNFL-mm/mm²) and retinal nerve fibre layer (RNFL-μm) thickness were quantified along with neurological and radiological assessments at baseline and after 2 years of follow-up. Age-matched, healthy controls (n = 20) were also assessed.

Results

In patients with RRMS compared with controls at baseline, CNFD (p = 0.004) and RNFL thickness (p < 0.001) were lower, and CNBD (p = 0.003) was higher. In patients with SPMS compared with controls, CNFD (p < 0.001), CNFL (p = 0.04) and RNFL thickness (p < 0.001) were lower. For identifying RRMS, CNBD had the highest area under the receiver operating characteristic (AUROC) curve (0.99); and for SPMS, CNFD had the highest AUROC (0.95). At follow-up, there was a further significant decrease in CNFD (p = 0.04), CNBD (p = 0.001), CNFL (p = 0.008) and RNFL (p = 0.002) in RRMS; in CNFD (p = 0.04) and CNBD (p = 0.002) in SPMS; and in CNBD (p = 0.01) in SPMS compared with RRMS. Follow-up corneal nerve loss was greater in patients with new enhancing lesions and optic neuritis history.

Conclusion

Progressive corneal and retinal axonal loss was identified in patients with MS, especially those with more active disease. CCM may serve as an imaging biomarker of axonal loss in MS.

Case 302: Supratentorial Lymphocytic Inflammation with Parenchymal Perivascular Enhancement Responsive to Steroids

HISTORY

Part one of this case appeared 4 months previously and may contain larger images. A 21-year-old immunocompetent man who was a long-term resident of Qatar presented to the emergency department with recurrent episodes of unprovoked generalized tonic-clonic seizures lasting 2-3 minutes that spontaneously resolved and were associated with postictal confusion. The patient also had progressive mild diplopia, intermittent dizziness, and numbness in the left arm over the course of 3 months. The patient did not have any other systemic symptoms or chronic medical diseases. He did not have any history of intake of illicit drugs, supplements, or regular medications; he had not received any recent vaccinations; and he had not undergone any surgical procedures. He had no history of travel. At presentation, vital signs were normal. Neurologic examination showed mild left homonymous hemianopia, normal gait with no cerebellar signs, and preserved sensations, power, tone, and reflexes in all four limbs. An electroencephalogram showed no epileptiform discharges. Chest CT and extensive laboratory work-up, including viral, fungal, bacterial, and parasite work-up, thyroid function tests, and immunologic blood tests yielded normal results. Those included normal complete and differential blood counts and normal serum chemistry. Serum analysis was negative for antinuclear antibody, Sjögren syndrome antigens A and B, cytoplasmic antineutrophil cvtoplasmic antibody, and paraneoplastic profile. Serum evaluation was also negative for human immunodeficiency virus type 1 and type 2 RNA, and Brucella, Schistosoma, and toxoplasma antibodies. Venereal Disease Research Laboratory (VDRL) and rapid plasma regain (RPR) test results were negative. Cerebrospinal fluid (CSF) analysis revealed clear fluid and normal pressure and biochemistry, except for elevated protein concentration (0.48 g/L) (normal range, 0.15-0.45 g/L). There were 43 leukocytes/µL (99% lymphocytes) (normal range, 0-5 leukocytes/µL; lymphocytes range, 40%-80%), with no atypical or malignant cells. CSF Gram staining, acid-fast staining, cryptococcal antigen, varicella-zoster virus polymerase chain reaction (PCR), herpes simplex virus PCR, VDRL, and RPR test results were negative. CSF cultures did not show any evidence of growth of bacteria, fungi, or acid-fast bacillus. CSF flow cytometry did not show a monoclonal lymphoid population. No CSF oligoclonal bands were detected. Conventional brain MRI with intravenous administration of contrast material and perfusion study were performed and included different sequences (Figs 1-3).

Abnormal corneal nerve morphology and brain volume in patients with schizophrenia

Neurodevelopmental and neurodegenerative pathology occur in Schizophrenia. This study compared the utility of corneal confocal microscopy (CCM), an ophthalmic imaging technique with MRI brain volumetry in quantifying neuronal pathology and its relationship to cognitive dysfunction and symptom severity in schizophrenia. Thirty-six subjects with schizophrenia and 26 controls underwent assessment of cognitive function, symptom severity, CCM and MRI brain volumetry. Subjects with schizophrenia had lower cognitive function (P ≤ 0.01), corneal nerve fiber density (CNFD), length (CNFL), branch density (CNBD), CNBD:CNFD ratio (P < 0.0001) and cingulate gyrus volume (P < 0.05) but comparable volume of whole brain (P = 0.61), cortical gray matter (P = 0.99), ventricle (P = 0.47), hippocampus (P = 0.10) and amygdala (P = 0.68). Corneal nerve measures and cingulate gyrus volume showed no association with symptom severity (P = 0.35–0.86 and P = 0.50) or cognitive function (P = 0.35–0.86 and P = 0.49). Corneal nerve measures were not associated with metabolic syndrome (P = 0.61–0.64) or diabetes (P = 0.057–0.54). The area under the ROC curve distinguishing subjects with schizophrenia from controls was 88% for CNFL, 84% for CNBD and CNBD:CNFD ratio, 79% for CNFD and 73% for the cingulate gyrus volume. This study has identified a reduction in corneal nerve fibers and cingulate gyrus volume in schizophrenia, but no association with symptom severity or cognitive dysfunction. Corneal nerve loss identified using CCM may act as a rapid non-invasive surrogate marker of neurodegeneration in patients with schizophrenia.

Case 302

History A 21-year-old immunocompetent man who was a long-term resident of Qatar presented to the emergency department with recurrent episodes of unprovoked generalized tonic-clonic seizures lasting 2-3 minutes that spontaneously resolved and were associated with postictal confusion. The patient also had progressive mild diplopia, intermittent dizziness, and numbness in the left arm over the course of 3 months. The patient did not have any other systemic symptoms or chronic medical diseases. He did not have any history of intake of illicit drugs, supplements, or regular medications; he had not received any recent vaccinations; and he had not undergone any surgical procedures. He had no history of travel. At presentation, vital signs were normal. Neurologic examination showed mild left homonymous hemianopia, normal gait with no cerebellar signs, and preserved sensations, power, tone, and reflexes in all four limbs. An electroencephalogram showed no epileptiform discharges. Chest CT and extensive laboratory work-up, including viral, fungal, bacterial, and parasite work-up, thyroid function tests, and immunologic blood tests yielded normal results. Those included normal complete and differential blood counts and normal serum chemistry. Serum analysis was negative for antinuclear antibody, Sjögren syndrome antigens A and B, cytoplasmic antineutrophil cvtoplasmic antibody, and paraneoplastic profile. Serum evaluation was also negative for human immunodeficiency virus type 1 and type 2 RNA, and Brucella, Schistosoma, and toxoplasma antibodies. Venereal Disease Research Laboratory (VDRL) and rapid plasma regain (RPR) test results were negative. Cerebrospinal fluid (CSF) analysis revealed clear fluid and normal pressure and biochemistry, except for elevated protein concentration (0.48 g/L) (normal range, 0.15-0.45 g/L). There were 43 leukocytes/µL (99% lymphocytes) (normal range, 0-5 leukocytes/µL; lymphocytes range, 40%-80%), with no atypical or malignant cells. CSF Gram staining, acid-fast staining, cryptococcal antigen, varicella-zoster virus polymerase chain reaction (PCR), herpes simplex virus PCR, VDRL, and RPR test results were negative. CSF cultures did not show any evidence of growth of bacteria, fungi, or acid-fast bacillus. CSF flow cytometry did not show a monoclonal lymphoid population. No CSF oligoclonal bands were detected. Conventional brain MRI with intravenous administration of contrast material and a perfusion study were performed and included different sequences (Figs 1-3).

Loss of corneal nerves and brain volume in mild cognitive impairment and dementia

Introduction

This study compared the capability of corneal confocal microscopy (CCM) with magnetic resonance imaging (MRI) brain volumetry for the diagnosis of mild cognitive impairment (MCI) and dementia.

Methods

In this cross‐sectional study, participants with no cognitive impairment (NCI), MCI, and dementia underwent assessment of Montreal Cognitive Assessment (MoCA), MRI brain volumetry, and CCM.

Results

Two hundred eight participants with NCI (n = 42), MCI (n = 98), and dementia (n = 68) of comparable age and gender were studied. For MCI, the area under the curve (AUC) of CCM (76% to 81%), was higher than brain volumetry (52% to 70%). For dementia, the AUC of CCM (77% to 85%), was comparable to brain volumetry (69% to 93%). Corneal nerve fiber density, length, branch density, whole brain, hippocampus, cortical gray matter, thalamus, amygdala, and ventricle volumes were associated with cognitive impairment after adjustment for confounders (All P’s < .01).

Discussion

The diagnostic capability of CCM compared to brain volumetry is higher for identifying MCI and comparable for dementia, and abnormalities in both modalities are associated with cognitive impairment.

Autoimmune encephalitis and seizures, cerebrospinal fluid, imaging, and EEG findings: a case series

Antibody-mediated encephalitides constitute a group of inflammatory brain diseases characterized by prominent neuropsychiatric symptoms and are associated with antibodies against neuronal cell-surface proteins, ion channels, or receptors. The diagnosis and management of autoimmune encephalitis include evaluation of the clinical presentation, brain imaging, cerebrospinal fluid (CSF) findings, antibody detection, and electroencephalography (EEG) findings. This is a retrospective study of adults 18 years or older with autoimmune encephalitis due to antibodies against membrane surface antigens as well as anti-glutamic acid decarboxylase (anti-GAD) antibodies. The electronic medical record was reviewed for demographic data, clinical data, laboratory results, EEG, and imaging findings. Antibody screening was requested for 341 patients between May 2014 and December 2019. Antibody screening was positive in 37 patients presenting with seizures and/or encephalopathy. Of these, 10 patients tested positive for antibodies against neuronal surface antigens or anti-GAD antibodies-2 patients had anti-GAD antibody encephalitis, 5 had anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis, and 3 had anti-leucine-rich glioma-inactivated 1 (anti-LGI1) encephalitis. Demographics, clinical presentation, EEG, imaging, and CSF findings are reported. Autoimmune encephalitides are a diverse group of disorders with a few common clinical features and MRI findings. MRI, EEG, and CSF findings can be normal or show nonspecific findings in autoimmune encephalitis. Therefore, early diagnosis of these disorders requires a high level of suspicion to avoid delaying the diagnosis. Carefully looking for diagnostic clinical features (e.g., faciobrachial dystonic seizures in anti-LGI1 encephalitis), significant findings in MRI (e.g., limbic encephalitis), and some EEG patterns (e.g., extreme delta brush and generalized rhythmic delta activity in anti-NMDAR encephalitis) may help in early diagnosis.

Corneal Nerve and Brain Imaging in Mild Cognitive Impairment and Dementia

Background:

Visual rating of medial temporal lobe atrophy (MTA) is an accepted structural neuroimaging marker of Alzheimer’s disease. Corneal confocal microscopy (CCM) is a non-invasive ophthalmic technique that detects neuronal loss in peripheral and central neurodegenerative disorders.

Objective:

To determine the diagnostic accuracy of CCM for mild cognitive impairment (MCI) and dementia compared to medial temporal lobe atrophy (MTA) rating on MRI.

Methods:

Subjects aged 60–85 with no cognitive impairment (NCI), MCI, and dementia based on the ICD-10 criteria were recruited. Subjects underwent cognitive screening, CCM, and MTA rating on MRI.

Results:

182 subjects with NCI (n = 36), MCI (n = 80), and dementia (n = 66), including AD (n = 19, 28.8%), VaD (n = 13, 19.7%), and mixed AD (n = 34, 51.5%) were studied. CCM showed a progressive reduction in corneal nerve fiber density (CNFD, fibers/mm²) (32.0±7.5 versus 24.5±9.6 and 20.8±9.3, p < 0.0001), branch density (CNBD, branches/mm²) (90.9±46.5 versus 59.3±35.7 and 53.9±38.7, p < 0.0001), and fiber length (CNFL, mm/mm²) (22.9±6.1 versus 17.2±6.5 and 15.8±7.4, p < 0.0001) in subjects with MCI and dementia compared to NCI. The area under the ROC curve (95% CI) for the diagnostic accuracy of CNFD, CNBD, CNFL compared to MTA-right and MTA-left for MCI was 78% (67–90%), 82% (72–92%), 86% (77–95%) versus 53% (36–69%) and 40% (25–55%), respectively, and for dementia it was 85% (76–94%), 84% (75–93%), 85% (76–94%) versus 86% (76–96%) and 82% (72–92%), respectively.

Conclusion:

The diagnostic accuracy of CCM, a non-invasive ophthalmic biomarker of neurodegeneration, was high and comparable with MTA rating for dementia but was superior to MTA rating for MCI.

COVID-19 related leukoencephalopathy with bilateral reticular formation involvement

We are presenting the imaging findings of COVID-19-related leukoencephalopathy associated with bilateral reticular formation diffusion restriction in brain magnetic resonance imaging. To the best of our knowledge, this is the first reported case of bilateral reticular formation affection in a COVID-19 patient.

Association of Cerebral Ischemia With Corneal Nerve Loss and Brain Atrophy in MCI and Dementia

Introduction

This study assessed the association of cerebral ischemia with neurodegeneration in mild cognitive impairment (MCI) and dementia.

Methods

Subjects with MCI, dementia and controls underwent assessment of cognitive function, severity of brain ischemia, MRI brain volumetry and corneal confocal microscopy.

Results

Of 63 subjects with MCI (n = 44) and dementia (n = 19), 11 had no ischemia, 32 had subcortical ischemia and 20 had both subcortical and cortical ischemia. Brain volume and corneal nerve measures were comparable between subjects with subcortical ischemia and no ischemia. However, subjects with subcortical and cortical ischemia had a lower hippocampal volume (P < 0.01), corneal nerve fiber length (P < 0.05) and larger ventricular volume (P < 0.05) compared to those with subcortical ischemia and lower corneal nerve fiber density (P < 0.05) compared to those without ischemia.

Discussion

Cerebral ischemia was associated with cognitive impairment, brain atrophy and corneal nerve loss in MCI and dementia.

Susceptibility-weighted Imaging in Neuroradiology: Practical Imaging Principles, Pearls and Pitfalls

Susceptibility-weighted imaging (SWI) was one of the recent and helpful advancement in magnetic resonance imaging. Its utilization -provided valuable information for the radiologists in multiple fields, including neuroradiology. SWI was able to demonstrate cerebral paramagnetic and diamagnetic substances. Therefore, the applications of this imaging technique were diverse in research and clinical neuroradiology. This article reviewed the basic technical steps, various clinical applications of SWI, and potential limitations. The practicing radiologist needs to be oriented about using SWI and phase images in the right- and left-handed MRI systems to demonstrate different brain pathologies, including neurovascular diseases, traumatic brain injuries, brain tumors, infectious and inflammatory, and neurodegenerative diseases.

Spectrum of neuroimaging findings in COVID-19

An outbreak of corona virus disease 2019 (COVID-19) began in China in December 2019, and rapidly spread to become a worldwide pandemic. Neurological complications encountered in hospitalized patients include acute arterial ischemic cerebrovascular stroke, cerebral venous thrombosis, critical illness-associated cerebral microbleeds, hypertensive hemorrhagic posterior reversible encephalopathy, meningoencephalitis/flare up of infections, flare up of multiple sclerosis, acute disseminated encephalomyelitis, cerebral hemodynamic/hypoxic changes such as watershed ischemic changes and hypoxic ischemic encephalopathy, and spine manifestations of Guillain Barre syndrome and viral myelitis. The purpose of our study is to illustrate the different neuroimaging features in critically ill hospitalized COVID-19 positive patients in the State of Qatar.

Critical illness-associated cerebral microbleeds in COVID-19

We are reporting the imaging findings of the rare entity of critical illness-associated cerebral microbleeds in a COVID-19-positive 66-year-old woman with hypoxic respiratory failure, who was eventually intubated and ventilated. Multiple scattered cerebral microhaemorrhages diffusely distributed in the juxtacortical white matter and internal capsule region, sparing the deep and periventricular white matter, basal ganglia, thalami and cortex were seen, which is a unique imaging finding in critically ill patients with respiratory failure and hypoxemia requiring mechanical ventilation. The mechanism underlying these microhaemorrhages relates to the endpoint of critical illness, rather than a specific underlying disease.

Rosai-Dorfman disease of cranial and spinal origin - A case series

Background

Rosai-Dorfman disease (RDD) is an idiopathic nonneoplastic lymphadenopathy disorder which is characterized by lymph node enlargement, but it may also presents primarily involving a variety of extranodal sites, including central nerves system and craniospinal axis. This study reports five cases of craniospinal RDD, with review of epidemiology, clinical presentation, imaging, and histopathological features with current management strategies.

Case Description

Five cases of RDD are diagnosed at Hamad General Hospital, Qatar, during 2013-2018. Two cases had dural-based cranial lesions with overlying cranial involvement while three cases were having extradural thoracic spine lesions. All cases underwent surgical intervention and confirmed by histopathology.

Conclusion

Craniospinal RDD is a rare clinical presentation and poses significant diagnostic challenges preoperatively due to its similarity with other neoplastic or inflammatory diseases. Surgical option to remove compressive neural pathology provides a good clinical outcome with no recurrence in long-term follow-up.

Primary Hypoparathyroidism Mimicking Ankylosing Spondylitis in a Young Man with Fahr's Syndrome: A Case Report

Patients with chronic idiopathic hypoparathyroidism may develop neurological complications, including calcification of the basal ganglia and other areas of the brain. In Fahr's syndrome, intracranial calcification is associated with an underlying disorder such as hypo or hyperparathyroidism. We report the case of a 37-year-old gentleman, with a history of bilateral cataract surgery and seizures, who presented with a new episode of seizure and was found to have severe hypocalcemia and bilateral symmetric intracranial calcification due to previously diagnosed primary hypoparathyroidism. He had symptoms and signs mimicking ankylosing spondylitis (AS), but with negative radiological and serological findings, not fitting into the diagnosis of axial spondyloarthropathies (SpA), as per standard criteria. Patients with long-standing idiopathic hypoparathyroidism can have severe calcification of soft tissues and bones, including vertebrae and paravertebral soft tissues, causing inflammatory back pain and stiffness. It is vital to report such cases as their occurrence is rare, and physicians should be aware of the possibility while evaluating patients with inflammatory back pain. Treatment in these cases is directed towards hypocalcemia and underlying primary pathology rather than spondyloarthropathy.

Artery of Percheron Infarct: A Rare Presentation of Acute Ischemic Stroke in a High-Risk Antiphospholipid Syndrome Patient

Artery of Percheron (AOP) is an abnormal variant of the arterial supply of the thalamus. AOP occlusion can lead to bilateral thalamic and rostral midbrain infarct presenting as memory loss, fluctuating levels of consciousness, and altered mental status. A 43-year-old woman with a history of antiphospholipid syndrome (APS), managed on dabigatran, presented with acute confusion and drowsiness. She had slurred and slowed speech, disorientation in time and place, left-sided facial droop, decreased power of the left side (4/5), and was unable to walk due to generalized weakness. Labs showed a prolonged prothrombin time and activated partial thromboplastin time, positive lupus anticoagulant, anti-cardiolipin, beta-2 glycoprotein, anti-nuclear and anti-dsDNA antibodies. Contrast-enhanced CT perfusion showed ischemic changes in the bilateral thalami, suggesting infarct along the AOP territory. AOP infarcts are scarce and the presenting complaints are unusual of cerebrovascular accidents. It requires a high index of suspicion to detect. There are no other reports in the literature of patients with APS presenting with an AOP infarct. Considering the lack of evidence, we recommend against the use of newer oral anticoagulants (NOACs) for secondary prevention of vascular events in patients with triple-positive APS.

A Case of Coronavirus Disease 2019 Presenting with Seizures Secondary to Cerebral Venous Sinus Thrombosis

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2. COVID-19-associated thrombotic events are recognized. A wide variety of neurological presentations have been recently documented. We report the first case of COVID-19 presenting with generalized seizure secondary to cerebral venous sinus thrombosis.

Acute Flaccid Myelitis in COVID-19

Spinal cord imaging findings in COVID-19 are evolving with the increasing frequency of neurological symptoms among COVID-19 patients. Several mechanisms are postulated to be the cause of central nervous system affection including direct virus neuroinvasive potential, post infectious secondary immunogenic hyperreaction, hypercoagulability, sepsis and possible vasculitis as well as systemic and metabolic complications associated with critical illness. Only a few case reports of spinal cord imaging findings are described in COVID-19, which include transverse myelitis, acute disseminated encephalomyelitis and post-infectious Guillain Barre’ syndrome. We are describing a case of myelitis which, to the best of our knowledge, is the first reported case of myelitis in COVID-19.

Mediastinal seminoma presenting as a neck mass falsely diagnosed as anaplastic thyroid carcinoma: A case report

Germ cell tumors can occur in the mediastinum. They account for about 20% of tumors at this location. The majority are located in the anterior mediastinum and usually occur in young adult males. Extension of mediastinal germ cell tumors into the neck with mass formation is a very rare and unusual event. Herein, we report a case of a 34 year old male who presented with a progressively enlarging neck mass. Fine Needle Aspiration (FNA) was performed as initial evaluation and showed cellular smears comprising atypical large cells with prominent irregular nucleoli and moderate amount of cytoplasm with lymphocytic infiltrate and some epithelioid granulomas in the background. The mass was misdiagnosed initially on the cytology smears as anaplastic thyroid carcinoma. The subsequent tissue core biopsy showed sheets and nests of atypical cells admixed with ill-defined granulomatous inflammation. By immunohistochemistry, the tumor cells were immunoreactive with SALL4, PLAP and OCT3/4, compatible with malignant germ cell tumor, seminomatous type. It is very rare for patients with primary mediastinal seminoma to present initially with a neck mass. Fine Needle Aspiration (FNA) of this "neck mass" can lead to misinterpretation of findings due to similarities in cytological features between malignant germ cell tumors and other undifferentiated malignant neoplasms and the diagnosis, therefore, can be very challenging.

Functional magnetic resonance imaging of head and neck cancer: Performance and potential

Functional magnetic resonance imaging (MRI) of tumors of the head and neck usually encompasses diffusion-weighted imaging (DWI) and intravenous (IV) contrast T1 dynamic perfusion imaging (DCE-MRI or PWI). Both techniques can characterize different tissues by probing into their microstructure, providing a novel approach in oncological imaging. In this pictorial review, we will cover the important technical aspects of DWI and PWI, the pathophysiological background and the current applications and potential of these functional MRI techniques in the imaging of head and neck cancer.

Imaging of Pediatric Chronic Neck Infections

Chronic neck infections in the pediatric population can have an indolent presentation that can mimic more serious conditions including neoplasia. Ultrasound remains a reliable primary modality for imaging of sialadenitis and infected congenital cystic neck lesions in children, whereas cross sectional imaging is needed if intervention is contemplated, to better evaluate multispatial involvement, lymph nodal morphology and distribution, and as the primary imaging modality to study more complex anatomy in case of ear infections.

CT Cisternography of Paradoxical Cerebrospinal Fluid Rhinorrhea after Operation for Acoustic Neuroma

Cerebrospinal fluid (CSF) rhinorrhea after acoustic neuroma surgery is a well-known complication. CT cisternography can be used to demonstrate the entry of CSF from cerebellopontine angle cistern into the mastoid air cells, middle ear and then into nasopharynx via Eustachian tube. We report a case of paradoxical CSF rhinorrhea after surgery for acoustic neuroma in which the path of CSF leak was accurately demonstrated using CT cisternography.

Perirolandic Sparing and Pituitary Apoplexy in Adult Brain with Global Hypoxia

Global hypoxia in adult brain usually manifests as ischemic lesions in watershed territories. Acute profound hypoxia involves the cortex especially the perirolandic area, white matter and deep grey matter. Perirolandic sparing in adult global hypoxia is not described in literature. Few cases of perirolandic sparing are described in conditions like anoxia in term infants in the post-neonatal period and hepatic encephalopathy. We report a case of global hypoxia in adult brain with perirolandic sparing and unique association with pituitary apoplexy. It is well known that the “diving reflex” redistribution of cerebral blood flow to the high metabolically active regions occurs when the hypoxic insult is prolonged and partial. The perirolandic sparing in our case could be explained by this phenomenon, wherein the patient acutely developed hypoxia, which was profound and prolonged but not prolonged enough for deep grey matter sparing.

Novel brain MRI abnormalities in Gitelman syndrome

Gitelman syndrome is an autosomal recessive renal tubular disorder characterized by hypokalemic metabolic alkalosis, hypomagnesemia and hypocalciuria. The syndrome is caused by a defective thiazide-sensitive sodium chloride co-transporter in the distal convoluted tubules of the kidneys. Gitelman syndrome could be confused with Bartter syndrome; the main differentiating feature is the presence of low urinary calcium excretion in the former. Descriptions of neuroradiological imaging findings associated with Gitelman syndrome are very scarce in the literature and include basal ganglia calcification, idiopathic intracranial hypertension and sclerochoroidal calcification. Cauda equina syndrome-like presentation has been reported, but without any corresponding imaging findings on lumbar spine MRI. We report a 13-year-old male with Gitelman syndrome who presented with altered mental status following a fall and scalp laceration and unremarkable brain CT, followed during hospitalization by somnolence and seizures. Metabolically the patient demonstrated hypokalemia and hypomagnesemia. MRI demonstrated features of encephalopathy including predominantly right-sided cerebral hemispheric signal abnormality and cytotoxic edema, with bilateral symmetric involvement of the thalami, midbrain tegmentum and tectum and cerebellar dentate nuclei. MRI after five months obtained during a later episode of encephalopathy showed resolution of the signal abnormalities with setting in of brain atrophy and also areas of newly developed cytotoxic edema in the left thalamus, bilateral dorsal midbrain and right greater than left dentate nuclei. The described abnormalities, either recurrent or in isolation, have not previously been published in patients with Gitelman syndrome. We believe that the findings are due to alteration of respiratory chain function secondary to the metabolic derangement and hence have a similar imaging appearance as encephalopathy related to mitochondrial cytopathy or metabolic encephalopathy.

Functional Magnetic Resonance Imaging (MRI) and MRI Tractography in Progressive Supranuclear Palsy-Like Syndrome

An 18-year-old woman underwent an uneventful ascending aortic aneurysm repair then developed progressive supranuclear palsy-like syndrome. Extensive neuroimaging including contrasted fat-suppressed cranial and orbital magnetic resonance imaging (MRI), MRI tractography, and functional MRI (fMRI) revealed no clear radiographic involvement except for a single tiny hypoechoic midbrain dot on the T2*-weighted gradient-echo imaging, which is not considered sufficient to account for the patient's deficits. This case attests to the occult nature of this rare and devastating syndrome.

Surgical approaches to central skull base and postsurgical imaging

The close proximity to or intricate involvement of critical neurovascular structures in the central skull base region or both present unique surgical challenges. Varied surgical approaches may be used to remove tumors in this region, including open craniotomies and minimally invasive transnasal or transfacial endoscopic approaches. The ideal surgical technique is chosen based on multiple factors including the aggressiveness, histopathology, and location of the tumor with respect to regional neurovascular elements. Postsurgical image analysis of the central skull base requires an intimate understanding of preoperative and expected postoperative appearance in relation to the nature of the excision and surgical materials used.

Vascular lesions of the central skull base region

The arterial and venous structures of the central skull base region form complex anatomical relationships with each other and with adjacent osseous and neural structures. Vascular structures including the cavernous sinuses and internal carotid arteries can be displaced, encased, or invaded by neoplastic, inflammatory, or infectious lesions of the central skull base. Consequently, the vascular structures have a unique role in determining the imaging appearance, clinical significance, and therapeutic options of lesions occurring in the central skull base. This article briefly reviews the basic anatomy of the cavernous sinus and the relationship of the internal carotid artery to the cavernous sinus and central skull base. The major imaging features of some common vascular lesions, including skull base aneurysm, carotid-cavernous fistula, and cavernous sinus thrombosis are presented.

MR anatomy of deep brain nuclei with special reference to specific diseases and deep brain stimulation localization

Diseases affecting the basal ganglia and deep brain structures vary widely in etiology and include metabolic, infectious, ischemic, and neurodegenerative conditions. Some neurologic diseases, such as Wernicke encephalopathy or pseudohypoparathyroidism, require specific treatments, which if unrecognized could lead to further complications. Other pathologies, such as hypertrophic olivary degeneration, if not properly diagnosed may be mistaken for a primary medullary neoplasm and create unnecessary concern. The deep brain structures are complex and can be difficult to distinguish on routine imaging. It is imperative that radiologists first understand the intrinsic anatomic relationships between the different basal ganglia nuclei and deep brain structures with magnetic resonance (MR) imaging. It is important to understand the "normal" MR signal characteristics, locations, and appearances of these structures. This is essential to recognizing diseases affecting the basal ganglia and deep brain structures, especially since most of these diseases result in symmetrical, and therefore less noticeable, abnormalities. It is also crucial that neurosurgeons correctly identify the deep brain nuclei presurgically for positioning deep brain stimulator leads, the most important being the subthalamic nucleus for Parkinson syndromes and the thalamic ventral intermediate nucleus for essential tremor. Radiologists will be able to better assist clinicians in diagnosis and treatment once they are able to accurately localize specific deep brain structures.

Rathke cleft cyst. MRI criteria for presumptive diagnosis

OBJECTIVE

To define MRI criteria for the presumptive diagnosis of Rathke cleft cyst (RCC).

METHODS

One hundred and three patient MRI scans suggesting RCC performed between January 2005 and January 2011 were retrospectively reviewed for indications, cyst location, T1 and T2 signal intensity, dimensions, encroachment on optic chiasm, enhancement pattern, and stability over a year.

RESULTS

Of the 103 patients analyzed, the suggestion of RCC was an incidental finding in 82.5% (n=85) of patients. Headache was the most common symptom in 11.6% (n=12), visual field deficit in 3.8% (n=4), and both headache and visual field deficit in 0.97% (n=1). The cyst was hyperintense on T1 in 55.3% (n=57), hypointense in 27.1% (n=28), and isointense in 17.4% (n=18). The cyst was T2 hyperintense in 57.2% (n=59), and iso-hypointense in 42.7% (n=54). The cyst showed no enhancement in 80.5% (n=83), and a thin marginal enhancement in 19.4% (n=20). The cyst showed a stable appearance in 99% (n=102) of patients after at least one year follow-up MRI study.

CONCLUSION

Rathke cleft cysts typically have a cystic appearance with T1 hyperintensity, sometimes with T1 iso- or hypointensity, variable T2 signal, and no or thin marginal enhancement and remain stable in size over time.

Radiopaque jaw lesions: an approach to the differential diagnosis

Radiopaque jaw lesions are frequently encountered at radiography and computed tomography, but they are usually underevaluated or underdescribed in radiology reports. A systematic approach to the evaluation of radiopaque jaw lesions is necessary to diagnose the lesion or at least provide a meaningful differential diagnosis. To evaluate a radiopaque jaw lesion, the first, most important step is to categorize the lesion according to its attenuation, its relationship to the teeth, and its location with respect to the tooth. These basic observations are essential to the evaluation of any type of jaw lesion. Once these observations have been made, it is easy to create a proper differential diagnosis. The presence of important characteristics, such as margination, a perilesional halo, bone expansion, and growth pattern, as well as whether the lesion is sclerotic, has ground-glass attenuation, or is mixed lytic and sclerotic, further narrows the differential diagnosis. It is important to note that some radiopaque jaw lesions may be entirely lucent early in their evolution. Awareness of the demographic distribution of these lesions and their associated clinical features, as well as the radiologic approach, is important to explore the "terra incognita" of radiopaque jaw lesions.

Primary hyperparathyroidism-related brown tumors mimicking other giant cell-containing skeletal tumors: role of correlative imaging in diagnosis

A patient initially suspected of having a giant cell granuloma was subsequently found-through additional imaging with (99m)Tc-sestamibi and ultrasound-to have osteolytic brown tumors caused by a parathyroid adenoma. Brown tumors that relate to primary hyperparathyroidism may mimic other skeletal tumors that contain giant cells, presenting difficulty with accurate diagnosis. Correlative imaging can have a valuable role in such cases, potentially avoiding the extensive work-up usually done for suspected bone metastases.

Unusual appearance and presentation of supratentorial subependymoma in an adult patient

We report a case of a large, heterogeneously enhancing, pathologically proven, supratentorial subependymoma in a 31-year-old male patient presenting with headache, nausea and vomiting as well as gait disturbances. Although most supratentorial subependymomas have distinctive MR features, our case demonstrated imaging findings that made it indistinguishable from other more aggressive malignant supratentorial intraventricular lesions. It is of paramount importance to consider supratentorial subependymomas in the differential diagnosis of supratentorial lesions, even if their radiological features were atypical.

Susac syndrome. A differential diagnosis for demyelination

Susac syndrome is a microangiopathy of unknown origin, probably autoimmune, affecting capillaries and precapillary arterioles of the brain, retina, and inner ear. It is often misdiagnosed as acute disseminated encephalomyelitis or multiple sclerosis. We report the case of a 25-year-old male with Susac syndrome who developed the clinical triad of encephalopathy, visual and hearing problems over the course of a year. The characteristic MRI findings including central corpus callosal involvement and brain infarctions were supported by branch retinal arterial/arteriolar occlusions on fluorescein retinal angiography. Most patients with Susac syndrome will not have the complete clinical triad initially. A very high index of suspicion is required by the clinician and radiologist in patients with any component of the clinical triad so as not to misdiagnose the MRI findings for demyelination. Even if initial ophthalmologic examinations are normal, these patients should be followed up for later development of branch retinal artery occlusions.