Publications by authors named "Nihaal Reddy"

13 Publications

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The spectrum of acute leukoencephalopathy with restricted diffusion (ALERD): A case series and review of literature.

Eur J Paediatr Neurol 2021 Jul 6;33:86-93. Epub 2021 Jun 6.

Department of Pediatric Neurology, Rainbow Children's Hospital, Hyderabad, Telangana, India. Electronic address:

Introduction: The clinico-etiological spectrum of Acute leukoencephalopathy with restricted diffusion (ALERD) is not well known in Indian population. This is likely to vary between populations and ethnicities.

Methods: We retrospectively reviewed the clinicoetiological spectrum of ALERD at a tertiary care pediatric center, and described the clinical, imaging, etiological spectrum and short-term outcomes.

Results: Eleven out of 78 children with non-traumatic encephalopathy presenting to our center had a final diagnosis of ALERD. The mean age at presentation was 34.9 months (6-80 months) and 63.6% were males. The monophasic course (72.7%) and the diffuse pattern (63.6%) on neuroimaging were predominant in these children. Dengue haemorrhagic fever was the commonest underlying/triggering infection (5 of 11 children). Ten children required mechanical ventilation in view of neurogenic respiratory failure, with mean duration of ventilation of 6.4 days (Range 2-10 days). The duration of hospital stay varied from 11 to 25 days (Mean - 15.3 days). One child (9 %) died, 6 children (54.5 %) had varying degrees of cognitive impairment and 4 (36.3 %) children had a normal outcome. Children with a shorter duration of ventilation seemed to have a better outcome.

Conclusion: Dengue haemorrhagic fever was the commonest cause, and diffuse imaging pattern with monophasic course was the commonest presentation in Indian children with ALERD. The clinical presentation and factors influencing outcome are possibly different from previously described literature.
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http://dx.doi.org/10.1016/j.ejpn.2021.05.017DOI Listing
July 2021

The complex relationship between estrogen and migraines: a scoping review.

Syst Rev 2021 03 10;10(1):72. Epub 2021 Mar 10.

Department of Plastic and Reconstructive Surgery, The Ohio State University Wexner Medical Center, 915 Olentangy River Rd, Columbus, OH, 43212, USA.

Background: Migraines are a chronic disease for millions worldwide and have been hypothesized to be hormonally mediated due to their higher prevalence in females and menstrual associations. Estrogen has been commonly implicated in migraine pathogenesis, yet its exact role in the pathophysiology of migraines has yet to be fully understood.

Method: We conducted a scoping review of the literature regarding estrogen's role in migraine pathogenesis and included 19 studies out of an initial 202 in the final review. Two independent reviewers screened and extracted data from included studies based on predetermined inclusions and exclusion criteria.

Results: The estrogen withdrawal hypothesis, discussed by 12 of the reviewed studies, is the most discussed theory about estrogen's role in migraine physiology and describes the association of migraine onset with natural declines in estrogen levels, particularly when estrogen levels fall below 45-50 pg/mL after an extended period of priming. Additional findings suggest that women with a history of migraine have an increased sensitivity to physiologic fluctuations in estradiol levels. Several studies suggest that migraines are associated with menstruation.

Conclusion: It appears that estrogen is very likely to play a key role in migraine pathogenesis, but seems to affect patients in different ways depending on their past medical history, age, and use of hormonal therapy. Further research is warranted to isolate the effects of estrogen in each unique patient population, and we believe that studies comparing menstruating women to postmenopausal women could help shed light in this area.
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http://dx.doi.org/10.1186/s13643-021-01618-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7948327PMC
March 2021

Relapsing Demyelinating Syndromes in Children: A Practical Review of Neuroradiological Mimics.

Front Neurol 2020 4;11:627. Epub 2020 Aug 4.

Department of Radiology, Great Ormond Street Hospital, London, United Kingdom.

Relapsing demyelinating syndromes (RDS) in children encompass a diverse spectrum of entities including multiple sclerosis (MS) acute disseminated encephalomyelitis (ADEM), aquaporin-4 antibody associated neuromyelitis optica spectrum disorder (AQP4-NMOSD) and myelin oligodendrocyte glycoprotein antibody disease (MOG-AD). In addition to these, there are "antibody-negative" demyelinating syndromes which are yet to be fully characterized and defined. The paucity of specific biomarkers and overlap in clinical presentations makes the distinction between these disease entities difficult at initial presentation and, as such, there is a heavy reliance on magnetic resonance imaging (MRI) findings to satisfy the criteria for treatment initiation and optimization. Misdiagnosis is not uncommon and is usually related to the inaccurate application of criteria or failure to identify potential clinical and radiological mimics. It is also notable that there are instances where AQP4 and MOG antibody testing may be falsely negative during initial clinical episodes, further complicating the issue. This article illustrates the typical clinico-radiological phenotypes associated with the known pediatric RDS at presentation and describes the neuroimaging mimics of these using a pattern-based approach in the brain, optic nerves, and spinal cord. Practical guidance on key distinguishing features in the form of clinical and radiological red flags are incorporated. A subsection on clinical mimics with characteristic imaging patterns that assist in establishing alternative diagnoses is also included.
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http://dx.doi.org/10.3389/fneur.2020.00627DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7417677PMC
August 2020

Pediatric Posterior Fossa Medulloblastoma: The Role of Diffusion Imaging in Identifying Molecular Groups.

J Neuroimaging 2020 07 12;30(4):503-511. Epub 2020 Jun 12.

Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN.

Background And Purpose: The molecular groups WNT activated (WNT), Sonic hedgehog activated (SHH), group 3, and group 4 are biologically and clinically distinct forms of medulloblastoma. We evaluated apparent diffusion coefficient (ADC) values' utility in differentiating/predicting medulloblastoma groups at the initial diagnostic imaging evaluation and prior to surgery.

Methods: We retrospectively measured the ADC values of the enhancing, solid portion of the tumor (EST) and of the whole tumor (WT) and performed Kruskal-Wallis testing to compare the absolute tumor ADC values and cerebellar and thalamic ratios of three medulloblastoma groups (WNT, SHH, and group 3/group 4 combined).

Results: Ninety-three children (65 males) were included. Fifty-seven children had group 3/group 4, 27 had SHH, and 9 had WNT medulloblastomas. The median absolute ADC values in the EST and WT were .719 × 10 and .864 × 10 mm /s for group 3/group 4; .660 × 10 and .965 × 10 mm /s for SHH; and .594 × 10 and .728 × 10 mm /s for WNT medulloblastomas (P = .02 and .13). The median ratio of ADC values in the EST or the WT to normal cerebellar tissue was highest for group 3/group 4 and lowest for WNT medulloblastomas (P = .03 and .09), with similar results in pairwise comparisons of the corresponding thalamic ADC values (P = .02 and .06).

Conclusion: ADC analysis of a tumor's contrast-enhancing solid portion may aid preoperative molecular classification/prediction of pediatric medulloblastomas and may facilitate optimal surgical treatment planning, reducing surgery-induced morbidity.
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http://dx.doi.org/10.1111/jon.12704DOI Listing
July 2020

Correction to: Venous pathologies in paediatric neuroradiology: from foetal to adolescent life.

Neuroradiology 2020 Jul;62(7):903

Monash Imaging, Monash Health, Melbourne, Australia.

The original version of this article unfortunately contained a referencing omission. Figure 11 is reused from the original publication of Figure 10 of Gunny and Lin [1].
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http://dx.doi.org/10.1007/s00234-020-02443-7DOI Listing
July 2020

Venous pathologies in paediatric neuroradiology: from foetal to adolescent life.

Neuroradiology 2020 Jan 9;62(1):15-37. Epub 2019 Nov 9.

Monash Imaging, Monash Health, Melbourne, Australia.

The interpretation of cerebral venous pathologies in paediatric practice is challenging as there are several normal anatomical variants, and the pathologies are diverse, involving the venous system through direct and indirect mechanisms. This paper aims to provide a comprehensive review of these entities, as their awareness can avoid potential diagnostic pitfalls. We also propose a practical classification system of paediatric cerebral venous pathologies, which will enable more accurate reporting of the neuroimaging findings, as relevant to the underlying pathogenesis of these conditions. The proposed classification system comprises of the following main groups: arterio-venous shunting-related disorders, primary venous malformations and veno-occlusive disorders. A multimodal imaging approach has been included in the relevant subsections, with a brief overview of the modality-specific pitfalls that can also limit interpretation of the neuroimaging. The article also summarises the current literature and international practices in terms of management options and outcomes in specific disease entities.
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http://dx.doi.org/10.1007/s00234-019-02294-xDOI Listing
January 2020

Ultrasound Predicts White Matter Integrity after Hypothermia Therapy in Neonatal Hypoxic-Ischemic Injury.

J Neuroimaging 2019 11 17;29(6):743-749. Epub 2019 Jun 17.

Neurosciences Intensive Care Nursery Group, Johns Hopkins University School of Medicine, Baltimore, MD.

Background: Hypoxic-ischemic injury (HII) is a major cause of neonatal death and neurodevelopmental disability. Head ultrasounds (HUS) in neonates with HII often show enhanced gray/white matter differentiation. We assessed the significance of this finding in predicting white matter structural integrity measured by diffusion tensor imaging (DTI) in neonates with HII.

Methods: We performed a quantitative region of interest-based analysis of white and gray matter echogenicity within the cingulate gyrus on pre- and posthypothermia HUS. We also completed a quantitative analysis of fractional anisotropy (FA) and mean (MD), axial (AD), and radial (RD) diffusivity within the bilateral anterior and posterior centrum semiovale (CSO) on posthypothermia brain magnetic resonance imaging. For HUS studies, we calculated a white-to-gray matter echogenicity ratio (WGR) and subsequently correlated it to DTI measurements.

Results: Forty-two term neonates with HII who underwent hypothermia therapy were included. Significant correlation was found between prehypothermia WGR and MD, AD, and RD values in the left anterior CSO (r = .38-.40, P = .02). Prehypothermia WGR also correlated with the following: MD and RD in the right anterior CSO (r = .35-.36, P = .04), MD and AD in the right posterior CSO (r = .32-.45, P = .008-.03), and AD in the left posterior CSO (r = .47, P = .005). No significant correlation was found either between prehypothermia WGR and FA values in the bilateral anterior and posterior CSO or between posthypothermia WGR and all DTI scalars in the bilateral anterior and posterior CSO.

Conclusions: Prehypothermia HUS WGR may predict posthypothermia white matter structural integrity and is potentially an early and easily obtainable biomarker of severity in neonatal HII.
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http://dx.doi.org/10.1111/jon.12644DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6814495PMC
November 2019

Comment on: Subspecialization in radiology - Is it time to hatch out of the cocoon?

Indian J Radiol Imaging 2019 Jan-Mar;29(1):106-107

Body Imaging, Department of Radiology, USF Health, Tampa, Florida, USA.

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http://dx.doi.org/10.4103/ijri.IJRI_511_17DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6467044PMC
April 2019

The neuroimaging mimics of abusive head trauma.

Eur J Paediatr Neurol 2019 Jan 22;23(1):19-30. Epub 2018 Nov 22.

Department of Neuroradiology, SickKids, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada.

Abusive head trauma (AHT) is a significant cause of morbidity and mortality in the paediatric population, typically in children under the age of two years. Neuroimaging plays a key role in the diagnostic work up of these patients as information regarding the mechanism of injury is often lacking and the findings on examination can be nonspecific. A number of conditions, both traumatic and atraumatic can mimic AHT based on neuroimaging features alone. The repercussions associated with a diagnosis or misdiagnosis of AHT can be severe and radiologists therefore need to be aware of and familiar with the imaging differentials of AHT. In this paper we review the imaging findings of the radiological mimics of AHT and focus on features that can help differentiate these entities from AHT.
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http://dx.doi.org/10.1016/j.ejpn.2018.11.006DOI Listing
January 2019

The Role of Diffusion Tensor Imaging in Detecting Hippocampal Injury Following Neonatal Hypoxic-Ischemic Encephalopathy.

J Neuroimaging 2019 03 16;29(2):252-259. Epub 2018 Oct 16.

Division of Pediatric Radiology and Pediatric Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD.

Background And Purpose: Neonatal hypoxic-ischemic injury of the brain and resultant encephalopathy (HIE) leads to major developmental impairments by school age. Conventional/anatomical MRI often fails to detect hippocampal injury in mild cases. We hypothesize that diffusion tensor imaging (DTI) has greater sensitivity for identifying subtle hippocampal injury.

Methods: We retrospectively analyzed DTI data collected from a cohort of neonates with HIE and controls. Conventional MRI sequences were classified qualitatively according to severity using a modified Barkovich scale. Using multivariate linear regression, we compared hippocampal DTI scalars of HIE patients and controls. Spearman correlation was used to test the association of DTI scalars in the hippocampal and thalamic regions. A multiple regression analysis tested the association of the DTI scalars with short-term outcomes.

Results: Fifty-five neonates with HIE (42% males) and 13 controls (54% males) were included. Hippocampal DTI scalars were similar between HIE and control groups, even when restricting the HIE group to those with moderate-to-severe injury (8 subjects). DTI scalars of the thalamus were significantly lower in the moderate-to-severely affected patients compared to controls (right fractional anisotropy [FA] .148 vs. .182, P = .01; left FA .147 vs. .181, P = .03). Hippocampal and thalamic DTI scalars were correlated (P < .001). Hippocampal DTI scalars were not associated with short-term outcomes.

Conclusions: Quantitative DTI analysis of the hippocampus in neonates following HIE is a feasible technique to examine neuronal injury. Although DTI scalars were useful in identifying thalamic injury in our cohort, hippocampal DTI analysis did not provide additional information regarding hippocampal injury following HIE.
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http://dx.doi.org/10.1111/jon.12572DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6403004PMC
March 2019

Neuroimaging Findings of Organic Acidemias and Aminoacidopathies.

Radiographics 2018 May-Jun;38(3):912-931

From the Division of Pediatric Radiology and Pediatric Neuroradiology, Russell H. Morgan Department of Radiology and Radiological Science (N.R., S.F.C., T.A.G.M.H., B.P.S.), and McKusick-Nathans Institute of Genetic Medicine, Department of Pediatrics (H.J.V.), The Johns Hopkins University School of Medicine, Charlotte R. Bloomberg Children's Center Bldg, Sheikh Zayed Tower, Room 4174, 1800 Orleans St, Baltimore, MD 21287-0842; Università degli Studi di Milano, Postgraduation School in Radiodiagnostics, Milan, Italy (S.F.C.); Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Md (H.J.V.); and Department of Pediatric Neurology, University Children's Hospital of Zurich, Zurich, Switzerland (E.B.).

Although individual cases of inherited metabolic disorders are rare, overall they account for a substantial number of disorders affecting the central nervous system. Organic acidemias and aminoacidopathies include a variety of inborn errors of metabolism that are caused by defects in the intermediary metabolic pathways of carbohydrates, amino acids, and fatty acid oxidation. These defects can lead to the abnormal accumulation of organic acids and amino acids in multiple organs, including the brain. Early diagnosis is mandatory to initiate therapy and prevent permanent long-term neurologic impairments or death. Neuroimaging findings can be nonspecific, and metabolism- and genetics-based laboratory investigations are needed to confirm the diagnosis. However, neuroimaging has a key role in guiding the diagnostic workup. The findings at conventional and advanced magnetic resonance imaging may suggest the correct diagnosis, help narrow the differential diagnosis, and consequently facilitate early initiation of targeted metabolism- and genetics-based laboratory investigations and treatment. Neuroimaging may be especially helpful for distinguishing organic acidemias and aminoacidopathies from other more common diseases with similar manifestations, such as hypoxic-ischemic injury and neonatal sepsis. Therefore, it is important that radiologists, neuroradiologists, pediatric neuroradiologists, and clinicians are familiar with the neuroimaging findings of organic acidemias and aminoacidopathies. RSNA, 2018.
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http://dx.doi.org/10.1148/rg.2018170042DOI Listing
October 2018
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