Neuroimaging Features of Biotinidase Deficiency

Biotinidase deficiency is an autosomal recessive condition caused by pathogenic variants in the BTD gene. Resultant deficiency of free biotin leads to impaired activity of the enzyme carboxylase and related neurologic, dermatologic, and ocular symptoms. Many of these are reversible on treatment, but early recognition and commencement of biotin supplementation are critical. This practice is especially important in countries where routine neonatal screening for biotinidase deficiency is not performed. In this report comprising 14 patients from multiple centers, we demonstrate the MR imaging patterns of this disorder at various age groups. Knowledge of these patterns in the appropriate clinical context will help guide early diagnosis of this treatable metabolic disorder.

Imaging Guidelines and Recommendations for Diagnosis, Surveillance, and Management of Pediatric CNS and Spinal Tumors

Central nervous system (CNS) tumors are the second most common cause of cancer in children when incidence rates of cancer are estimated according to the Indian population dynamics based on 2011 consensus. As per the estimates, CNS tumors account for 20.1% of cancer burden in children aged between 0 and 14 years and 16.8% when 0 to 19 years age group is considered. The most common pediatric brain tumors are astrocytoma and medulloblastoma followed by other embryonal tumors, craniopharyngioma, and ependymal tumors. The incidence of CNS tumors in children from India is similar to the western high-income countries, other than slightly higher incidence of craniopharyngioma in Indian children.

Mitochondrial Leukoencephalopathy in a One and Half-Year-old Boy

A one and half-year-old baby boy presented with subacute regression of milestones in all domains. On examination, he had spastic dystonic quadriparesis. Reflexes were brisk. Magnetic resonance imaging of the brain showed diffuse cavitating leukodystrophy involving bilateral periventricular white matter, centrum semiovale, and corona radiata. Magnetic resonance spectroscopy revealed a lactate peak and serum lactate levels were also elevated. Genetic studies revealed compound heterozygous autosomal recessive mutations in IBA57 gene. This case illustrates a rare mitochondrial encephalopathy called multiple mitochondrial dysfunction syndrome-3 caused by a novel IBA57 gene mutation.

Neurological and Neuroradiological Patterns with COVID-19 Infection in Children: A Single Institutional Study

Background Varied neurological manifestations in pediatric patients with coronavirus disease 2019 (COVID-19) have been increasingly reported from all across the world in the scientific literature.

Objective We aimed to evaluate pediatric cases with neurological symptoms and neuroimaging findings with COVID-19 infection in our hospital.

Materials and Methods Children from 0 to 12 years with laboratory evidence of COVID-19 infection and acute neurological manifestations within 3 months, who have undergone magnetic resonance imaging (MRI) were included in the study. We categorized them based on neurological findings into four groups: acute encephalitis syndrome (AES), acute flaccid paralysis (AFP), cerebrovascular event/stroke, and miscellaneous consisting of acute seizures without encephalopathy.

Results A total of 19 children with neurological manifestations related to COVID-19 infection were included in the study. AES was the most common neurological syndrome seen in 47.36%, followed by AFP in 26.31% and cardiovascular event/stroke in 21.05%. Seizure was the most common neurological symptoms in 62.15%, followed by encephalopathy in 42.10% and AFP in 26.31%. On neuroimaging, pattern observed were immune-mediated cauda equina nerve roots enhancement in 26.31% or acute disseminated encephalitis in 5.26%, small acute infarcts, hippocampal, and bilateral thalamic signal changes seen in 21.05% each, microhemorrhages and leukoencephalopathy in 15.78%, and coinfection in 5.26%.

Conclusion In our study, seizures and encephalopathy were the most common neurological symptoms with COVID-19 infection. Postinfectious immune-mediated cauda equina nerve root enhancement or acute demyelinating encephalomyelitis–like brain imaging, followed by small acute infarcts and hippocampal/thalamic signal changes were most common imaging patterns. We found overlapping neurological and MRI patterns in many children, suggesting that various pathophysiological mechanisms act individually or synergistically.

Basal Ganglia Germinoma in an Adolescent: A Case Report

Germ cell tumors are rare tumors and may pose a diagnostic dilemma. We present a 15-year-old boy with insidious onset right hemiparesis followed by polyuria and polydipsia. Later, he also developed cognitive decline and speech disturbances. Serial magnetic resonance images (MRIs) over a 2-year period showed progressive atrophy of the left caudate nucleus, along with Wallerian degeneration of the left internal capsule and crus of midbrain. Further in the course, imaging revealed an ill-defined signal intensity involving left ganglio-capsulo-thalamic region with increased perfusion which was suggestive of basal ganglia germinoma. Beta human chorionic gonadotropin levels were mildly elevated. This case illustrates an uncommon presentation of a central nervous system germinoma which is often misdiagnosed in the early stages because of its atypical symptomatology and MRI findings.

The role of stoichiometry in superconducting Nb1-βSnβ: electronic and vibrational properties from ab initio calculations

Using first principles calculations based on density functional theory, the electronic, vibrational and superconducting properties of compounds with different stoichiometry ratios in the A15 phase have been studied. To this purpose, the λ mass enhancement parameter, which determines the superconducting critical temperature through the Allen-Dynes modification of the McMillan formula, has been explicitly calculated in the context of the density functional perturbation theory that allows the calculation of the matrix elements of the electron-phonon interactions at different compositions related to the Sn content. Our results provide a better understanding of the inhomogeneous composition of one of the most widely employed low-temperature superconductors, evidencing the electronic properties and the phonon modes that are responsible for the critical temperature degradation as the Sn concentration is varied.

Magnetic resonance imaging of optic nerve

Optic nerves are the second pair of cranial nerves and are unique as they represent an extension of the central nervous system. Apart from clinical and ophthalmoscopic evaluation, imaging, especially magnetic resonance imaging (MRI), plays an important role in the complete evaluation of optic nerve and the entire visual pathway. In this pictorial essay, the authors describe segmental anatomy of the optic nerve and review the imaging findings of various conditions affecting the optic nerves. MRI allows excellent depiction of the intricate anatomy of optic nerves due to its excellent soft tissue contrast without exposure to ionizing radiation, better delineation of the entire visual pathway, and accurate evaluation of associated intracranial pathologies.

Acute Wallerian degeneration of middle cerebellar peduncles due to basilar artery thrombosis

Wallerian degeneration (WD) is the process of demyelination and disintegration of the distal axonal segment following the interruption of the axonal integrity or damage to the neuron. We report a patient having WD of middle cerebellar peduncles due to pontine infarction caused by basilar artery thrombosis. We review the anatomy and discuss the pathogenesis of this condition.

Multiple intracranial meningiomas and cavernous hemangiomas

Intracerebral meningiomas and cavernous hemangiomas (hemangiomas, cavernomas) are entities frequently encountered by neuroradiologists and neurosurgeons. Even multiple tumors can often be observed in patients with certain congenital conditions, eg. multiple meningiomas in neurofibromatosis type 2 or multiple cavernous hemangiomas in familial cavernous malformations. However, there are only very few reported cases of concurrent meningiomas and cavernous hemangiomas, all but one related to prior radiotherapy. We describe the second case of concurrent multiple meningiomas and cavernous hemangiomas occurring de novo without a history of radiation.

Tilting angle and water slippage over hydrophobic coatings

Hydrophobic coatings, such as octadecyltrichlorosilane or n-alkyl monolayers, enhance the slippage of liquids on solid walls. For a given alkyl chain length, the main structural parameter for homogeneous coatings is the tilt angle between coating molecules and the surface normal. In this paper, ab initio calculations are used to calculate the equilibrium configuration of coating molecules, showing that the tilt angle easily changes from 0° to 30° depending on the specific head group binding the solid substrate. These values are used to set up classical molecular dynamics of water slippage over the coatings using different water models (Transferable Intermolecular Potential 3 point (TIP3P), Transferable Intermolecular Potential 4 point (TIP4P) and TIP4P/2005). The slippage is found to be robust with respect to the coating tilting, while a slight dependence on the water model is observed.