Differential diagnosis of T2 hyperintense brainstem lesions: Part 2. Diffuse lesions

A Rare Case of Atypical Hemolytic Uremic Syndrome Presenting as Chronic Interstitial Nephritis

Atypical hemolytic uremic syndrome commonly presents as rapidly progressive renal failure and is histologically characterized by thrombotic microangiopathy (TMA). TMA presenting with acute renal failure requires aggressive medical management. Here, we present a case of a 30-year-old man who presented with a history of accelerated hypertension and a strong family history of end-stage renal disease, in September 2023. Upon evaluation, he was found to have a creatinine level of 2 mg/dl, bland urine and normal-sized kidneys; a renal biopsy revealed chronic interstitial nephritis. Genetic analysis for autosomal dominant tubulointerstitial kidney disease and nephronophthisis yielded negative results. The patient was managed with antihypertensive medications. In January 2024, he was admitted with a history of confusion, headache, and alcohol binge. He had a blood pressure of 200/100 mmHg and had grade 3 hypertensive retinopathy. Laboratory tests revealed anemia with thrombocytopenia, bland urine, normal coagulation parameters, indirect hyperbilirubinemia, normal-sized kidneys on ultrasound, and elevated lactate dehydrogenase levels. MRI of the brain revealed symmetrical hyperintensities in bilateral cerebellum and the dorsal brainstem. Complement levels revealed low C3 levels and genetic analysis revealed a homozygous deletion in the complement factor H-related 3 (CFHR3) gene. The autoantibody for complement factor H was negative. The patient was managed conservatively with adequate blood pressure control. This case highlights the effects of complement dysregulation on the renal tubulointerstitium.

Central Pontine Myelinolysis as a Late Complication After Hyponatremia and COVID-19 Infection

Osmotic demyelination syndrome (ODS) is a rare but serious condition that is hypothesized to be a result of rapid correction of hyponatremia, with a catastrophic prognosis. The foci of demyelination may occur in either the pontine area or within the white matter of the cerebral hemispheres, which denotes a specific clinical presentation. We present the case of a post-COVID-19 patient who was diagnosed with ODS with typical clinical and radiological characteristics of both forms: central pontine myelinolysis and extrapontine myelinolysis. The clinical assessment of ODS encompasses a variety of differential diagnoses, including stroke, neuroinfection, neoplasia, and other demyelinating diseases. A specific characteristic of ODS is the delayed clinical manifestation after the hyponatremic state. Furthermore, it is noteworthy that there might be discrepancies between the clinical manifestations and the neuroimaging findings. The association between COVID-19 and ODS is unclear at the moment, although it can possibly be explained by the viral infection through multiple mechanisms such as renal dysfunction, diarrhea, or vomiting. ODS should be considered in cases of hyponatremia and neurological deterioration during the course of COVID-19 infection. Despite the fact that early detection and treatment of this syndrome can reduce the risk of short-term mortality and long-term disability, they do not guarantee complete recovery.

A Case of Central Pontine Myelinolysis Unrelated Serum Sodium Level in Traumatic Brain Injury Patient

Central pontine myelinolysis (CPM) is a disorder wherein variable symptoms are associated with pontine dysfunction. It has been known to occur inconstantly, particularly when serum sodium in patients with prolonged hyponatremia is rapidly corrected. Further, it is known that patients with liver diseases, malnutrition, malignancy, adrenal insufficiency, and metabolic derangements are more vulnerable to this disorder. However, there is limited literature about the occurrence of CPM in patients with traumatic brain injury, especially in those with normal serum sodium levels. A 36-year-old man having no medical history was bought to our hospital due to an open skull fracture and underwent surgery. During the hospitalization period, he showed a sudden pseudobulbar palsy and rigidity. Imaging study of the brain was characteristic for CPM. He had no fluctuation of serum sodium levels during the hospitalization period. We speculate that the brain trauma itself might cause a CPM, and its pathophysiology may not be related to rapid serum sodium correction.

Relapsing Bickerstaff Brainstem Encephalitis After Autologous Stem Cell Transplant

Bickerstaff brainstem encephalitis, widely considered to be associated with Miller Fisher and Guillain-Barré syndromes, is a rare disease state defined by the triad of ophthalmoplegia, ataxia, and decreased consciousness. The presence of central nervous system involvement, commonly in the form of impaired arousal, solidifies it as a unique entity. We present a case of this rare syndrome after autologous stem cell transplant.

Magnetic resonance imaging of the brainstem in children, part 2: acquired pathology of the pediatric brainstem

Part 1 of this series of two articles describes conventional and advanced MRI techniques that are useful for evaluating brainstem pathologies. In addition, it provides a review of the embryology, normal progression of myelination, and clinically and radiologically salient imaging anatomy of the normal brainstem. Finally, it discusses congenital diseases of the brainstem with a focus on distinctive imaging features that allow for differentiating pathologies. Part 2 of this series of two articles includes discussion of neoplasms; infections; and vascular, demyelinating, toxic, metabolic and miscellaneous disease processes affecting the brainstem. The ultimate goal of this pair of articles is to empower the radiologist to add clinical value in the care of pediatric patients with brainstem pathologies.

Detecting the Uncommon Imaging Manifestations of Posterior Reversible Encephalopathy Syndrome (PRES) in Adults: a Comprehensive Illustrated Guide for the Trainee Radiologist

Posterior reversible encephalopathy syndrome (PRES) has traditionally been described as a reversible leukoencephalopathy with a distinct pattern of posteriorly distributed vasogenic oedema involving the subcortical regions of parietal and occipital lobes. PRES commonly occurs in the setting of hypertensive emergencies, pre-eclampsia/eclampsia, impaired renal function, and immunosuppressive therapy. The various clinical presentations of PRES include encephalopathy, seizures, headache, visual, and focal neurological deficits. As knowledge of this entity grows, the range of clinical, and radiological features is seen to be much broader than originally described. The brain oedema may not always be posteriorly distributed and the syndrome may not be uniformly reversible. Of special note are some uncommon imaging features (unilateral cerebral involvement, and isolated posterior fossa involvement) and also some uncommon complications (haemorrhage, cytotoxic oedema, and vasoconstriction). These red herrings may lead to potential diagnostic challenges and pitfalls especially for trainee radiologists, who often read these scans in an emergency setting. Early and accurate diagnosis is crucial for prompt optimum management, thereby avoiding residual morbidity. This review article focusses on the atypical radiological features of PRES in adults with extensive case-based imaging examples. A brief description of the pathophysiology, clinical, and classic radiological features of PRES has also been included. A tabulated summary of potential mimics with diagnostic pearls is provided to highlight pertinent take home points and to serve as an easy guide for day-to-day clinical practice.

A rare case of spinal dural arteriovenous fistula mimicking malignant glioma of the medulla oblongata: Significance of cerebral angiography for accurate diagnosis of brain stem region

Background:

The findings of a hyperintense sign on T2-weighted imaging (T2-WI) and gadolinium (Gd) contrast enhancement on magnetic resonance imaging (MRI) of the brain stem suggest malignant glioma. However, this pathological condition is probably uncommon, and it may be unknown that a dural arteriovenous fistula (DAVF) can imitate this radiological pattern. In addition, it is extremely rare to be caused by a spinal DAVF. Here, a rare case of spinal DAVF that mimicked malignant glioma of the medulla oblongata is presented.

Case Description:

A 56-year-old woman was admitted with a progressive gait disturbance, vertigo, and dysphasia. MRI showed a hyperintense signal in the medulla oblongata on fluid-attenuated inversion recovery (FLAIR) and moderate contrast enhancement on Gd-enhanced MRI. Interestingly, Gd-enhanced MRI demonstrated abnormal dilated veins around the brain stem and cervical spinal cord. Cerebral angiography showed spinal DAVF at the left C4/C5 vertebral foramen fed by the C5 radicular artery. The fistula drained into spinal perimedullary veins and flowed out retrograde at the cortical vein of the posterior cranial fossa. Therefore, surgical disconnection of the spinal DAVF was performed by a posterior approach. The patient’s postoperative course was uneventful. Cerebral angiography showed complete disappearance of the DAVF, with marked reductions of the hyperintense sign of the medulla oblongata on FLAIR.

Conclusion:

This important case illustrates MRI findings mimicking brain stem glioma. In cases with the hyperintense sign-on T2-WI associated with contrast enhancement suspicious of brainstem glioma, careful checking for perimedullary abnormal vessels and additional cerebral angiography should be performed.

Isolated pontine involvement in posterior reversible encephalopathy syndrome with coincidental acute ischaemic stroke

Posterior reversible encephalopathy syndrome (PRES) is a cliniconeuroradiological syndrome characterised by a unique reversible pattern on imaging and total regression of clinical symptoms and signs. We describe an unusual case of PRES with isolated pontine involvement with coincidental acute ischaemic stroke in a 60-year-old man who presented with headache, unsteadiness of gait, blurred vision and elevated blood pressure. MRI scan revealed an expanded pons with diffuse T2 and Fluid attenuated Inversion Recovery (FLAIR) hyperintensities and an acute infarct in the right temporal lobe. A diagnosis of PRES was considered most likely after exclusion of other differentials and the patient was started on antihypertensive treatment as for hypertensive encephalopathy. He became asymptomatic after controlling blood pressure and the follow-up MRI scan at 3 weeks showed complete resolution of the pontine high signals which confirmed the diagnosis of PRES.

Brainstem astrocytoma as a neuro-Behçet's disease mimic

A 58-year-old man with a history of recurrent aphthous ulcers since childhood was admitted to the hospital with acute neurological decline characterised by loss of motor dexterity, dysarthria, dysphagia and unsteady gait. MRI brain was significant for symmetrical hyperintense T2 fluid attenuated inversion recovery (FLAIR) in the corticospinal tracts, including parts of the pons and the mesodiencephalic junction. Though initial concern was for neuro-Behçet's disease, brain biopsy ultimately revealed a diagnosis of astrocytoma. This report demonstrates a mimic of neuro-Behçet's disease and the importance of confirming the correct diagnosis prior to initiating therapy.

Lessons to Be Remembered from a Dural Arteriovenous Fistula Mimicking Medulla and High Cervical Cord Glioma

The radiological signs of intracranial dural arteriovenous fistulas (ICDAVFs) are heterogenous. While it is commonly accepted that hyper intense T2 wedge magnetic resonance imaging of the brainstem and cervical cord mainly concern gliomas, it is so far uncommon and probably unknown that ICDAVFs can imitate similar radiological pattern, especially with gadolinium contrast enhancement and cord enlargement. Thus the angiography is poorly documented in the diagnostic workup. We report the unusual history of ICDAVFs, revealed by clinical and radiological features that mimicked a medulla or cervical spinal cord glioma. This observation provides information on the management of atypical lesions mimicking medulla or cervical cord glioma and arguments for a careful radiological study. Looking for dilated veins around the brainstem and the cord is mandatory in the workup of a supposed infiltrating brainstem or spinal cord lesion, in order to rule out an ICDAVF. Even if the hyperintense T2 images associated with contrast enhancement is in favor of a brainstem or spinal cord glioma, additional cerebral angiography should be mandatory. Moreover, this clinical case highlights the need for a multidisciplinary approach including neuroradiologist, oncologist and neurosurgeon.

Brainstem glioma: Prediction of histopathologic grade based on conventional MR imaging

Objective The objective of this article is to investigate the association between specific MR imaging findings and histopathologic grading (low-grade vs. high-grade) of brainstem gliomas (BSGs). Methods Sixty-two males and 34 females (mean (standard deviation, SD) age of 24.61 (17.20) years, range = 3 to 70 years) with histologically diagnosed BSG underwent conventional 1.5 T MR imaging, which included T1-weighted (T1W), T2W, and post-contrast T1W sequences. There were 39 children (mean age of 9.38 years) and 57 adults (mean age of 35 years). A binary logistic regression analysis was used to explore associations between MRI features and histopathological grade of the BSG. Results Binary logistic regression revealed that necrosis (adjusted odds ratio (OR) = 16.07; 95% confidence interval (CI) = 3.20 to 80.52; p = 0.001) and inhomogeneous contrast enhancement (adjusted OR = 8.04; 95% CI = 1.73 to 37.41; p = 0.008) as significant predictors of high-grade BSG. The equation (Nagelkerke R²= 0.575) is Logit ( p high-grade BSG) = (2.77 × necrosis) + (2.08 × heterogeneous contrast enhancement) - 3.13. Sensitivity and specificity values were respectively 66.7% and 96.0% for necrosis and 85.7% and 65.9% for inhomogeneous contrast-enhancing lesions. In the pediatric age group, only inhomogeneous contrast enhancement (adjusted OR = 40; 95% CI = 3.95 to 445.73; p = 0.002) was a significant predictor for high-grade BSG. Conclusion Conventional MR imaging features such as necrosis and inhomogeneous contrast enhancement in adults and heterogeneous contrast enhancement in children suggest high-grade BSG.

Central Variant of Posterior Reversible Encephalopathy Syndrome - A Rare Case Report

Posterior Reversible Encephalopathy Syndrome (PRES) is a clinicoradiological condition associated with headache, altered mental status, dizziness and white matter vasogenic oedema in parieto-occipital region. It is often associated with hypertension but can also occur in diverse clinical settings like immunosuppression, eclampsia, etc. It is due to failure of autoregulatory mechanism of posterior circulation in response to change in blood pressure. We hereby report a rare case of central variant of PRES secondary to severe hypertension diagnosed with 3T MRI. Objective of reporting this case was to describe the imaging findings of typical and rare atypical patterns of PRES. A 71-year-old male hypertensive patient was referred for brain imaging with history of short period of loss of consciousness, headache and dizziness. MRI brain showed central variant pattern of PRES with preferential involvement of brainstem, thalami and periventricular white matter with sparing of frontal, parietal and occipital lobes. The patient was treated with anti-hypertensive after which patient's symptoms subsided. The patient was followed up conservatively. Atypical variants of PRES should be borne in mind when pontine hyperintensity is encountered in hypertensive patient.

Rhombencephalitis: pictorial essay

The term rhombencephalitis refers to inflammatory diseases affecting the hindbrain (brainstem and cerebellum). Rhombencephalitis has a wide variety of etiologies, including infections, autoimmune diseases, and paraneoplastic syndromes. Infection with bacteria of the genus Listeria is the most common cause of rhombencephalitis. Primary rhombencephalitis caused by infection with Listeria spp. occurs in healthy young adults. It usually has a biphasic time course with a flu-like syndrome, followed by brainstem dysfunction; 75% of patients have cerebrospinal fluid pleocytosis, and nearly 100% have an abnormal brain magnetic resonance imaging scan. However, other possible causes of rhombencephalitis must be borne in mind. In addition to the clinical aspects, the patterns seen in magnetic resonance imaging can be helpful in defining the possible cause. Some of the reported causes of rhombencephalitis are potentially severe and life threatening; therefore, an accurate initial diagnostic approach is important to establishing a proper early treatment regimen. This pictorial essay reviews the various causes of rhombencephalitis and the corresponding magnetic resonance imaging findings, by describing illustrative confirmed cases.

Magnetic resonance imaging differential diagnosis of brainstem lesions in children

Differential diagnosis of brainstem lesions, either isolated or in association with cerebellar and supra-tentorial lesions, can be challenging. Knowledge of the structural organization is crucial for the differential diagnosis and establishment of prognosis of pathologies with involvement of the brainstem. Familiarity with the location of the lesions in the brainstem is essential, especially in the pediatric population. Magnetic resonance imaging (MRI) is the most sensitive and specific imaging technique for diagnosing disorders of the posterior fossa and, particularly, the brainstem. High magnetic static field MRI allows detailed visualization of the morphology, signal intensity and metabolic content of the brainstem nuclei, together with visualization of the normal development and myelination. In this pictorial essay we review the brainstem pathology in pediatric patients and consider the MR imaging patterns that may help the radiologist to differentiate among vascular, toxico-metabolic, infective-inflammatory, degenerative and neoplastic processes. Helpful MR tips can guide the differential diagnosis: These include the location and morphology of lesions, the brainstem vascularization territories, gray and white matter distribution and tissue selective vulnerability.

Middle cerebellar peduncles: Magnetic resonance imaging and pathophysiologic correlate

We describe common and less common diseases that can cause magnetic resonance signal abnormalities of middle cerebellar peduncles (MCP), offering a systematic approach correlating imaging findings with clinical clues and pathologic mechanisms. Myelin abnormalities, different types of edema or neurodegenerative processes, can cause areas of abnormal T2 signal, variable enhancement, and patterns of diffusivity of MCP. Pathologies such as demyelinating disorders or certain neurodegenerative entities (e.g., multiple system atrophy or fragile X-associated tremor-ataxia syndrome) appear to have predilection for MCP. Careful evaluation of concomitant imaging findings in the brain or brainstem; and focused correlation with key clinical findings such as immunosuppression for progressive multifocal leukoencephalopahty; hypertension, post-transplant status or high dose chemotherapy for posterior reversible encephalopathy; electrolyte disorders for myelinolysis or suspected toxic-drug related encephalopathy; would yield an appropriate and accurate differential diagnosis in the majority of cases.

Temozolomide after radiotherapy in recurrent "low grade" diffuse brainstem glioma in adults

Diffuse brainstem glioma is a rare disease in adults. Radiotherapy (RT) is usually considered to be the standard treatment. However, the role of chemotherapy in treating relapses after RT is unclear, and this study aimed to assess the use of temozolomide (TMZ) in this situation. We conducted a retrospective analysis of patients from our database with "low grade" adult diffuse infiltrating brainstem glioma who received TMZ at relapse after failing RT. The patients were diagnosed by histology or MRI criteria compatible with a low-grade glioma. The tumors were localized in the pons, medulla oblongata or midbrain, excluding supratentorial or infratentorial tumors that had infiltrated the brainstem secondarily. The patients' clinical and radiological responses were assessed, and their progression free survival (PFS) and overall survival (OS) time were estimated. Fifteen adult patients (median age 34 years) fulfilled the inclusion criteria. Histological analysis was available in 5 cases and showed grade II oligodendroglioma (2 cases), grade II oligoastrocytoma (2 cases), and grade II astrocytoma (1 case). Ten patients were selected by MRI criteria only. All patients received RT as initial treatment and had a median PFS of 34.2 months (95 % CI 24.1-44.2). The median KPS at the time of relapse was 80. TMZ was administered orally at 150-200 mg/m(2) for 5 days, every 28 days. Clinical improvement after TMZ was observed in 9 cases (60 %), whereas radiological assessment detected responses in 6/15 cases, including 4 partial and 2 minor responses. The estimated median PFS after TMZ was 9.5 months (95 % CI 7.9-11), and the median OS was 14.4 months (95 % CI 10.5-18.2). Grade 3 thrombopenia was observed in 26 % of cases. TMZ could be useful after RT failure in adult patients with recurrent diffuse "low grade" brainstem glioma.

Central pontine myelinolysis in advanced HIV infection with tuberculosis and multicentric Castleman's disease

Summary

We present a case of central pontine myelinolysis (CPM) in a patient with advanced HIV infection and miliary tuberculosis. While hospitalized the patient developed an unusual ataxic variant of CPM with full clinical recovery. Follow-up imaging revealed resolution of pontine lesions. To our knowledge, this is the first report of a clinical and radiological recovery from CPM in advanced HIV disease. Our report extends our knowledge of neurological presentations in patients with advanced HIV infection. It highlights the importance of considering CPM in patients with advanced HIV disease presenting with an ataxic syndrome, even in the absence of an electrolyte derangement.