Neuroimaging findings of Zika virus infection: a review article

Zika virus (ZIKV) is an arbovirus from the Flaviviridae family. It is usually transmitted by mosquito bite. There have been no reports of severe symptoms caused by ZIKV infection up until the last few years. In October 2013 an outbreak was reported in French Polynesia with severe neurological complications in some affected cases. In November 2015, the Ministry of Health of Brazil attributed the increased number of neonatal microcephaly cases in northeastern Brazil to congenital ZIKV infection. The rapid spread of the virus convinced the World Health Organization to announce ZIKV infection as a “Public Health Emergency of International Concern” in February 2016. The main neuroimaging findings in congenital ZIKV infection include microcephaly which is the hallmark of the disease, other malformations of cortical development (e.g., lissencephaly, heterotopia, etc.), parenchymal calcifications, unilateral or bilateral ventriculomegaly, enlarged extra-axial CSF spaces, dysgenesis of the corpus callosum, agenesis of the cavum septum pellucidum, cerebellar and brainstem hypoplasia, and ocular abnormalities. ZIKV infection may also cause Guillain-Barré syndrome and acute disseminated encephalomyelitis in adults. Familiarity with neuroimaging findings of congenital and acquired ZIKV infection is crucial to suspect this disease in residents of endemic regions and travelers to these areas.     

Neuroimaging findings of <Emphasis Type="Italic">congenital</Emphasis> Zika virus infection: a pictorial essay

Zika virus (ZIKV) is a mosquito-borne arbovirus from the Flaviviridae family. It had caused several epidemics since its discovery in 1947, but there was no significant attention to this virus until the recent outbreak in Brazil in 2015. The main concern is the causal relationship between prenatal ZIKV infection and congenital microcephaly, which has been confirmed recently. Moreover, ZIKV may cause other central nervous system abnormalities such as brain parenchymal atrophy with secondary ventriculomegaly, intracranial calcification, malformations of cortical development (such as polymicrogyria, and lissencephaly-pachygyria), agenesis/hypoplasia of the corpus callosum, cerebellar and brainstem hypoplasia, sensorineural hearing-loss, and ocular abnormalities as well as arthrogryposis in the infected fetuses. Postnatal (acquired) ZIKV infection usually has an asymptomatic or mildly symptomatic course, while prenatal (congenital) ZIKV infection has a more severe course and may cause severe brain anomalies that are described as congenital Zika syndrome. In this pictorial essay, we aim to illustrate the prenatal and postnatal neuroimaging findings that may be seen in fetuses and neonates with congenital Zika syndrome, and will discuss possible radiological differential diagnoses. A detailed knowledge of these findings is paramount for an early correct diagnosis, prognosis determination, and counseling of the affected children and families.     

Neuroimaging findings of <Emphasis Type="Italic">postnatally acquired</Emphasis> Zika virus infection: a pictorial essay

Zika virus (ZIKV) is a mosquito-borne arbovirus from the Flaviviridae family, first discovered in 1947. There has been no report of severe complications caused by this virus in humans until recently. However, it is confirmed now that prenatally acquired ZIKV infection may cause severe congenital brain abnormalities in the infected fetuses. In addition, there has been an increasing number of reports during recent years about the causal relationship between postnatally acquired ZIKV infection and severe neurologic complications (mostly immune-mediated ones). Hence, ZIKV should not be considered as benign as it was initially thought, but it might be seen as a serious global threat to human health that may severely affect not only fetuses. In this pictorial essay, we aim to describe and illustrate the currently recognized spectrum of neuroimaging findings in postnatally acquired ZIKV infection. Although neurologic complications do not frequently occur in postnatal ZIKV infection, it is important to be aware of them because they may cause high morbidity and mortality in the affected patients. In addition to clinical and laboratory findings, neuroimaging may help in the diagnostic work-up to make the correct diagnosis, determine the extent of the disease, and follow the clinical course.     

Neuroimaging findings in alcohol-related encephalopathies

OBJECTIVE: Our aim was to review the emergent neuroimaging findings of alcohol-related CNS nontraumatic disorders. Alcohol (ethanol) promotes inflammatory processes, increases DNA damage, and creates oxidative stress. In addition, the accompanying thiamine deficiency may lead to Wernicke encephalopathy. Associated changes in serum osmolarity may lead to acute demyelination. CONCLUSION: Alcohol-related encephalopathies can be life-threatening conditions but can be prevented or treated, if recognized.     

Neuroimaging findings in sickle cell disease

At least 25% of individuals with sickle cell disease will have a neurological complication over their lifetime, often as early as in childhood. Neuroradiological findings in patients with sickle cell disease are common and include acute territorial infarction, silent ischaemia and intracranial haemorrhage. Imaging abnormalities are typically, but not always, manifestations of the underlying vasculopathy. Coexisting acute and chronic pathology may pose challenges to interpretation.     

Sustained attention in psychosis: Neuroimaging findings

To provide a systematic review of scientific literature on functional magnetic resonance imaging (fMRI) studies on sustained attention in psychosis. We searched PubMed to identify fMRI studies pertaining sustained attention in both affective and non-affective psychosis. Only studies conducted on adult patients using a sustained attention task during fMRI scanning were included in the final review. The search was conducted on September 10^th, 2013. 15 fMRI studies met our inclusion criteria: 12 studies were focused on Schizophrenia and 3 on Bipolar Disorder Type I (BDI). Only half of the Schizophrenia studies and two of the BDI studies reported behavioral abnormalities, but all of them evidenced significant functional differences in brain regions related to the sustained attention system. Altered functioning of the insula was found in both Schizophrenia and BDI, and therefore proposed as a candidate trait marker for psychosis in general. On the other hand, other brain regions were differently impaired in affective and non-affective psychosis: alterations of cingulate cortex and thalamus seemed to be more common in Schizophrenia and amygdala dysfunctions in BDI. Neural correlates of sustained attention seem to be of great interest in the study of psychosis, highlighting differences and similarities between Schizophrenia and BDI.     

Neuroimaging findings in children with retinopathy-confirmed cerebral malaria

Purpose

To describe brain CT findings in retinopathy-confirmed, paediatric cerebral malaria.

Materials and methods

In this outcomes study of paediatric cerebral malaria, a subset of children with protracted coma during initial presentation was scanned acutely. Survivors experiencing adverse neurological outcomes also underwent a head CT. All children had ophthalmological examination to confirm the presence of the retinopathy specific for cerebral malaria. Independent interpretation of CT images was provided by two neuroradiologists.

Results

Acute brain CT findings in three children included diffuse oedema with obstructive hydrocephalus (2), acute cerebral infarctions in multiple large vessel distributions with secondary oedema and herniation (1), and oedema of thalamic grey matter (1). One child who was reportedly normal prior to admission had parenchymal atrophy suggestive of pre-existing CNS injury.Among 56 survivors (9-84 months old), 15 had adverse neurologic outcomes—11/15 had a follow-up head CT, 3/15 died and 1/15 refused CT. Follow-up head CTs obtained 7-18 months after the acute infection revealed focal and multifocal lobar atrophy correlating to regions affected by focal seizures during the acute infection (5/11). Other findings were communicating hydrocephalus (2/11), vermian atrophy (1/11) and normal studies (3/11).

Conclusions

The identification of pre-existing imaging abnormalities in acute cerebral malaria suggests that population-based studies are required to establish the rate and nature of incidental imaging abnormalities in Malawi. Children with focal seizures during acute cerebral malaria developed focal cortical atrophy in these regions at follow-up. Longitudinal studies are needed to further elucidate mechanisms of CNS injury and death in this common fatal disease.     

Neuroimaging findings in a suprasellar granular cell tumor

A 27-year-old woman presented with a history of amenorrhea, visual disturbance, and diabetes insipidus. Magnetic resonance imaging showed a large enhancing suprasellar mass with associated edema involving the left striatum. The lesion was hypometabolic on fluorodeoxyglucose-positron emission tomography. At surgery, a subtotal resection of a vascular tumor that appeared to arise from the posterior pituitary and hypothalamus was carried out. Pathologic examination revealed a granular cell tumor. We report the preoperative neuroimaging findings in this rare posterior pituitary stalk tumor.     

Neuroimaging findings in late infantile GM1 gangliosidosis.

Late infantile GM1 gangliosidosis is an extremely rare metabolic disorder with clinical features of seizure and progressive motor and mental retardation without facial dysmorphism or visceral organomegaly. We report the CT and MR imaging findings in one infant, which included abnormalities of the cerebral cortex, white matter, and deep nuclei.     

Neuroimaging findings in pediatric Wernicke encephalopathy: a review

Wernicke encephalopathy (WE) is an acute neurological disease resulting from dietary thiamine (vitamin B1) deficiency. WE is characterized by changes in consciousness, ocular dysfunction, and ataxia. Neuroradiologic findings usually show symmetric signal intensity alterations in the mammillary bodies, medial thalami, tectal plate, and periaqueductal area. Selective involvement of the cranial nerve nuclei, cerebellum, red nuclei, dentate nuclei, fornix, splenium, cerebral cortex, and basal ganglia characterize nonalcoholic WE patients. Furthermore, symmetric basal ganglia alterations with involvement of the putamen have only been observed in children. The incidence of WE is underestimated in both adult and pediatric patients. Interestingly, the frequency of WE in children appears to be similar to that observed in adults. The prognosis of the disease largely depends on the time from diagnosis to thiamine supplementation. The aim of this pediatric literature review is to provide an update on neuroradiologic findings in children affected by WE in an effort to determine pertinent clinical and imaging findings that can improve the detection and early identification of the disease. A thorough knowledge of the MRI findings of WE will assist in arriving at an early diagnosis, thereby reducing the morbidity and mortality associated with this disease in children.     

Post-traumatic cerebral infarction. Neuroimaging findings, etiology and outcome

Purpose: To assess the radiological characteristics of post-traumatic cerebral infarctions (PTCIs), the etiology and site of infarction, and to provide neuroimaging indicators of a poor clinical outcome.Material and Methods: A retrospective study of 16 patients with the neuroimaging-based diagnosis of PTCI was carried out. All CT, MR examinations, cerebral angiograms and medical records of the patients were reviewed.Results: Infarcts were diagnosed in the territory of the posterior cerebral artery in 9 patients, in the middle cerebral artery in 5, in the anterior cerebral artery in 3, lenticulostriate-thalamoperforating in 2, vertebrobasilar in 3, and cortical infarcts in 2 patients. Neuroimaging studies suggested focal mass effect and/or acquired intracranial herniations as the cause of infarction in 13/16 patients (81.2%). In 3/16 patients (18.8%), PTCI was due to vascular injury of which 2 were angiographically documented (carotid artery dissection). Eight of the 16 patients in this study died or were left in a persistent vegetative state. Patients with associated subdural hematoma, brain swelling/edema and traumatic subarachnoid hemorrhage (tSAH) exhibited the worst outcome.Conclusion: Gross mechanical shift of the brain and herniation across the falx and/or tentorium accounted for infarction in a majority of cases in our study. The overall death rate was 43.8% and this result suggests that PTCI is an indication of a poor clinical outcome, especially among patients with associated subdural hematoma, brain swelling/edema and tSAH.     

West Nile virus infection: MR imaging findings in the nervous system

BACKGROUND AND PURPOSE: West Nile virus (WNV) infection is an ongoing seasonal epidemic. We correlated the MR imaging findings with the clinical presentations and outcomes of WNV infection. METHODS: We reviewed 14 brain and three spinal MR images: nonenhanced and contrast-enhanced T1-weighted images (T1WIs) and T2-weighted images (T2WIs), nonenhanced fluid-attenuated inversion recovery (FLAIR) images (11 patients) and enhanced FLAIR images (three patients), with diffusion-weighted (DW) images and apparent diffusion coefficient maps. WNV infection was diagnosed by means of enzyme-linked immunosorbent assay with a plaque reduction neutralization test. We also correlated the MR findings with the clinical presentation, course, and outcome to determine their prognostic importance. RESULTS: MR imaging findings included: 1) normal (five patients); 2) DW imaging-only abnormalities in the white matter, corona radiata, and internal capsule (four patients); 3) hyperintensity on FLAIR images and T2WIs in the lobar gray and white matter, cerebellum, basal ganglia, thalamus and internal capsule, pons and midbrain (three patients); 4) meningeal involvement (two patients); and 5) spinal cord, cauda equina, and nerve root involvement (three patients). All patients with finding 1 and all but one with finding 2 recovered completely. Two patients with finding 3 died. Those with finding 4 or 5 had residual neurologic deficits that were severe or moderate to severe, respectively. CONCLUSION: Patients with normal MR images or abnormalities on only DW images had the best prognosis, while those with abnormal signal intensity on T2WI and FLAIR images had the worst outcomes. No definite predilection for any specific area of the brain parenchyma was noted.