Enhancing cranial nerves and cauda equina: an emerging magnetic resonance imaging pattern in metachromatic leukodystrophy and krabbe disease

Tumour mimics in paediatric neuroimaging

Distinguishing tumours from other conditions is a primary challenge in paediatric neuro-radiology. This paper aims to describe mimics, which are non-neoplastic conditions that have features similar to a neoplastic process caused by a non-neoplastic entity, and chameleons, which are uncommon presentations of brain tumours that are mistaken for other diagnoses. By doing so, we aim to raise awareness of these conditions and prevent inappropriate investigations or treatment in children. When suspecting a brain tumour, a detailed history, physical examination, and appropriate laboratory investigations can provide important clues about the nature of the lesion and narrow the list of possible differential diagnoses. Presented here is a collection of cases that have puzzled us for various reasons, including the absence of symptoms, coincidental timing, or misleading radiological features. Included in this pictorial essay are cases in which only a biopsy has helped us to make the correct diagnosis, as well as cases in which an unsuccessful biopsy has allowed us to evaluate hypotheses that were previously unaddressed. The paper also highlights the limited knowledge we have about the intercausality between malformations and later onset tumours, and the spectrum of manifestations that metabolic and genetic disorders can have.

Progressive demyelinating polyneuropathy after hematopoietic cell transplantation in metachromatic leukodystrophy: a case series

Metachromatic leukodystrophy (MLD) is a neuro-metabolic disorder due to arylsulfatase A deficiency, causing demyelination of the central and peripheral nervous system. Hematopoietic cell transplantation (HCT) can provide a symptomatic and survival benefit for pre-symptomatic and early symptomatic patients by stabilizing CNS disease. This case series, however, illustrates the occurrence of severely progressive polyneuropathy shortly after HCT in two patients with late-infantile, one with late-juvenile, and one with adult MLD, leading to the inability to walk or sit without support. The patients had demyelinating polyneuropathy before HCT, performed at the ages of 2 years in the first two patients and at 14 and 23 years in the other two patients. The myeloablative conditioning regimen consisted of busulfan, fludarabine and, in one case, rituximab, with anti-thymocyte globulin, cyclosporine, steroids, and/or mycophenolate mofetil for GvHD prophylaxis. Polyneuropathy after HCT progressed parallel with tapering immunosuppression and paralleled bouts of infection and graft-versus-host disease (GvHD). Differential diagnoses included MLD progression, neurological GvHD or another (auto)inflammatory cause. Laboratory, electroneurography and pathology investigations were inconclusive. In two patients, treatment with immunomodulatory drugs led to temporary improvement, but not sustained stabilization of polyneuropathy. One patient showed recovery to pre-HCT functioning, except for a Holmes-like tremor, for which a peripheral origin cannot be excluded. One patient showed marginal response to immunosuppressive treatment and died ten months after HCT due to respiratory failure. The extensive diagnostic and therapeutic attempts highlight the challenge of characterizing and treating progressive polyneuropathy in patients with MLD shortly after HCT. We advise to consider repeat electro-neurography and possibly peripheral nerve biopsy in such patients. Nerve conduction blocks, evidence of the presence of T lymphocytes and macrophages in the neuronal and surrounding nerve tissue, and beneficial effects of immunomodulatory drugs may indicate a partially (auto)immune-mediated pathology. Polyneuropathy may cause major residual disease burden after HCT. MLD patients with progressive polyneuropathy could potentially benefit from a more intensified immunomodulatory drug regime following HCT, especially at times of immune activation.

Magnetic resonance imaging enhancement of spinal nerve roots in a boy with X-linked adrenoleukodystrophy before diagnosis of chronic inflammatory demyelinating polyneuropathy

We present a boy with X-linked adrenoleukodystrophy (X-ALD) who was found to have lumbar nerve root enhancement on a screening MRI of the spine. The MRI was performed for lower extremity predominant symptoms. Several weeks after this MRI, he developed leg pain and was averse to walking long distances. He was diagnosed with Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) with electromyography, nerve conduction studies, and serial imaging. His case is consistent with CIDP in association with X-ALD based on improvement with intravenous immunoglobulin (IVIG) with continued contrast enhancement and lower extremity symptoms 8 weeks after his initial scans. Contrast enhancement of nerve roots has not been previously described in X-ALD. Nerve root enhancement has been seen in other leukodystrophies such as globoid cell leukodystrophy and metachromatic leukodystrophy. This case also demonstrates comorbid X-ALD with CIDP and highlights possible mechanisms from the literature for this association. We also review the broad differential of cauda equina nerve root enhancement.

MRI pattern recognition in white matter disease

Magnetic resonance imaging (MRI) pattern recognition is a powerful tool for quick diagnosis of genetic and acquired white matter disorders. In many cases, distribution and character of white matter abnormalities directly point to a specific diagnosis and guide confirmatory testing. Knowledge of normal brain development is essential to interpret white matter changes in young children. MRI is also used for disease staging and treatment decisions in leukodystrophies and acquired disorders as multiple sclerosis, and as a biomarker to follow treatment effects.

A New Pattern of Brain and Cord Gadolinium Enhancement in Molybdenum Cofactor Deficiency: A Case Report

Molybdenum cofactor deficiency (MoCD) is a rare and severe autosomal recessive in-born error of metabolism caused by the mutation in MOCS1, MOCS2, MOCS3 or GEPH genes, with an incidence ranging between 1 in 100,000 and 200,000 live births. The clinical presentation with seizures, lethargy and neurologic deficits reflects the neurotoxicity mediated via sulphite accumulation, and it occurs within the first hours or days after birth, often leading to severe neurodegeneration and the patient's death within days or months. The Imaging of Choice is a brain-specific MRI technique, which is usually performed without contrast and shows typical radiological findings in the early phase, such as diffuse cerebral oedema and infarction affecting the cortex and the basal ganglia and the white matter, as well as in the late phase, such as multicystic encephalomalacia. Our case report represents a novelty in the field, since the patient underwent a contrast-enhanced MRI to exclude a concomitant infectious disease. In the frame of the clinical presentation and laboratory data, we describe the MoCD Imaging findings for MRI morphological and advanced sequences, presenting a new contrast-enhanced MRI pattern characterized by the diffuse and linear leptomeningeal enhancement of brain, cord and spinal roots. The early identification of molybdenum cofactor deficiency is crucial because it may lead to the best multidisciplinary therapy for the patient, which is focused on the prompt and optimal management of the complications.

Pediatric-Onset Chronic Inflammatory Demyelinating Polyneuropathy: A Multicenter Study

BACKGROUND

To evaluate the clinical features, demographic features, and treatment modalities of pediatric-onset chronic inflammatory demyelinating polyneuropathy (CIDP) in Turkey.

METHODS

The clinical data of patients between January 2010 and December 2021 were reviewed retrospectively. The patients were evaluated according to the Joint Task Force of the European Federation of Neurological Societies and the Peripheral Nerve Society Guideline on the management of CIDP (2021). In addition, patients with typical CIDP were divided into two groups according to the first-line treatment modalities (group 1: IVIg only, group 2: IVIg + steroid). The patients were further divided into two separate groups based on their magnetic resonance imaging (MRI) characteristics.

RESULTS

A total of 43 patients, 22 (51.2%) males and 21 (48.8%) females, were included in the study. There was a significant difference between pretreatment and post-treatment modified Rankin scale (mRS) scores (P < 0.05) of all patients. First-line treatments include intravenous immunoglobulin (IVIg) (n = 19, 44.2%), IVIg + steroids (n = 20, 46.5%), steroids (n = 1, 2.3%), IVIg + steroids + plasmapheresis (n = 1, 2.3%), and IVIg + plasmapheresis (n = 1, 2.3%). Alternative agent therapy consisted of azathioprine (n = 5), rituximab (n = 1), and azathioprine + mycophenolate mofetil + methotrexate (n = 1). There was no difference between the pretreatment and post-treatment mRS scores of groups 1 and 2 (P > 0.05); however, a significant decrease was found in the mRS scores of both groups with treatment (P < 0.05). The patients with abnormal MRI had significantly higher pretreatment mRS scores compared with the group with normal MRI (P < 0.05).

CONCLUSIONS

This multicenter study demonstrated that first-line immunotherapy modalities (IVIg vs IVIg + steroids) had equal efficacy for the treatment of patients with CIDP. We also determined that MRI features might be associated with profound clinical features, but did not affect treatment response.

Leukodystrophies

PURPOSE OF REVIEW

This article reviews the most common leukodystrophies and is focused on diagnosis, clinical features, and emerging therapeutic options.

RECENT FINDINGS

In the past decade, the recognition of leukodystrophies has exponentially increased, and now this class includes more than 30 distinct disorders. Classically recognized as progressive and fatal disorders affecting young children, it is now understood that leukodystrophies are associated with an increasing spectrum of neurologic trajectories and can affect all ages. Next-generation sequencing and newborn screening allow the opportunity for the recognition of presymptomatic and atypical cases. These new testing opportunities, in combination with growing numbers of natural history studies and clinical consensus guidelines, have helped improve diagnosis and clinical care. Additionally, a more granular understanding of disease outcomes informs clinical trial design and has led to several recent therapeutic advances. This review summarizes the current understanding of the clinical manifestations of disease and treatment options for the most common leukodystrophies.

SUMMARY

As early testing becomes more readily available through next-generation sequencing and newborn screening, neurologists will better understand the true incidence of the leukodystrophies and be able to diagnose children within the therapeutic window. As targeted therapies are developed, it becomes increasingly imperative that this broad spectrum of disorders is recognized and diagnosed. This work summarizes key advances in the leukodystrophy field.

Spinal Nerve Roots Abnormalities on MRI in a Child with SURF1 Mitochondrial Disease

Variants in SURF1, encoding an assembly factor of mitochondrial respiratory chain complex IV, cause Leigh syndrome (LS) and Charcot-Marie-Tooth type 4K in children and young adolescents. Magnetic resonance imaging (MRI) appearance of enlarged nerve roots with postcontrastographic enhancement is a distinctive feature of hypertrophic neuropathy caused by onion-bulb formation and it has rarely been described in mitochondrial diseases (MDs). Spinal nerve roots abnormalities on MRI are novel findings in LS associated with variants in SURF1. Here we report detailed neuroradiological and neurophysiologic findings in a child with LS and demyelinating neuropathy SURF1-related. Our case underlines the potential contributive role of spinal neuroimaging together with neurophysiological examination to identify the full spectrum of patterns in MDs. It remains to elucidate if these observations remain peculiar of SURF1 variants or potentially detectable in other MDs with peripheral nervous system involvement.

Acute-onset paralytic strabismus in toddlers is important to consider as a potential early sign of late-infantile Metachromatic Leukodystrophy

OBJECTIVES

Metachromatic leukodystrophy (MLD) is a fatal lysosomal storage disease characterized by progressive demyelination within the central and peripheral nervous system. Rapid diagnosis is crucial in view of evolving therapeutic options. Strabismus has anecdotally been described as a feature in children with MLD. Our first aim was to examine the prevalence of strabismus as an early or even presenting sign of MLD in two nationwide cohorts. Second, we aimed to investigate the temporal relation between the onset of strabismus and gross motor deterioration, other early onset eye movement disorders and brain white matter abnormalities.

METHODS

Clinical records of 204 MLD patients at the University Children's Hospital Tubingen and Amsterdam University Medical Center were reviewed on the presence of strabismus and other eye movement disorders. Gross motor deterioration and white matter abnormalities on brain MRI were evaluated by using the Gross Motor Function Classification in MLD and MLD LOES score, respectively.

RESULTS

We identified strabismus as an early sign in MLD patients with the late-infantile form, with a prevalence of 27% (N = 17). The onset of strabismus preceded gross motor symptoms and brain white matter abnormalities in 71% and 46% respectively of the cases. Important characteristics were an acute-onset paralytic esotropia, partly accompanied by other eye movement abnormalities, and gadolinium enhancement of the cranial nerves.

CONCLUSIONS

Acute-onset paralytic strabismus in toddlers should be considered a potential early sign of late-infantile MLD and might result from early cranial nerve involvement. Brain MRI with gadolinium contrast may facilitate early diagnosis.

Comprehensive clinical, biochemical, radiological and genetic analysis of 28 Turkish cases with suspected metachromatic leukodystrophy and their relatives

Metachromatic leukodystrophy (MLD) is a glycosphingolipid storage disease caused by deficiency of the lysosomal enzyme arylsulfatase A (ASA) or its activator protein saposin B. MLD can affect all age groups in severity varying from a severe fatal form to milder adult onset forms. Diagnosis is usually made by measuring leukocyte ASA activity. However, this test can give false negative or false positive laboratory results due to pseudodeficiency of ASA and saposin B deficiency, respectively. Therefore, we aimed to evaluate patients with suspected MLD in a Turkish population by comprehensive clinical, biochemical, radiological, and genetic analyses for molecular and phenotypic characterization. We analyzed 28 suspected MLD patients and 41 relatives from 24 families. ASA activity was found to be decreased in 21 of 28 patients. Sixteen patients were diagnosed as MLD (11 late infantile, 2 juvenile and 3 adult types), 2 MSD, 2 pseudodeficiency (PD) and the remaining 8 patients were diagnosed as having other leukodystrophies. Enzyme analysis showed that the age of onset of MLD did not correlate with residual ASA activity. Sequence analysis showed 11 mutations in ARSA, of which 4 were novel (p.Trp195GlyfsTer5, p.Gly298Asp, p.Arg301Leu, and p.Gly311Asp), and 2 mutations in SUMF1 causing multiple sulfatase deficiency, and confirmed the diagnosis of MLD in 2 presymptomatic relatives. All individuals with confirmed mutations had low ASA activity and urinary sulfatide excretion. Intra- and inter-familial variability was high for the same ARSA missense genotypes, indicating the contribution of other factors to disease expression. Imaging findings were evaluated through a modified brain MRI scoring system which indicated patients with protein-truncating mutations had more severe MRI findings and late-infantile disease onset. MRI findings were not specific for the diagnosis. Anti-sulfatide IgM was similar to control subjects, and IgG, elevated in multiple sulfatase deficiency. In conclusion, the knowledge on the biochemical, clinical and genetic basis of MLD was expanded, a modified diagnostic laboratory algorithm for MLD based on integrated evaluation of ASA activity, urinary sulfatide excretion and genetic tests was devised.

Spontaneous Third Ventriculostomy in Krabbe Disease

INTRODUCTION

Spontaneous third ventriculostomies have been reported in relation to obstructive hydrocephalus and increased intracranial pressure and are most commonly seen as disruption of the floor of the third ventricle. Hydrocephalus has been reported in patients with Krabbe disease; however, it is clinically difficult to monitor for hydrocephalus in patients with Krabbe disease as symptoms of increased intracranial pressure may overlap with symptoms of Krabbe disease. We describe a case series of spontaneous third ventriculostomy and hydrocephalus, likely in response to increased intracranial pressure, in patients with infantile Krabbe disease.

METHODS

Brain magnetic resonance images of patients with infantile Krabbe disease were retrospectively analyzed to assess for ventricular size and presence of spontaneous third ventriculostomies. A brain atlas was used to standardize the calculation of ventricular size. Mid-sagittal, T2-weighted images around the third ventricle were assessed for spontaneous third ventriculostomies. Developmental outcomes were measured with a series of standardized and validated tests.

RESULTS

Seventy-five patients with infantile Krabbe disease were evaluated. Twelve cases of spontaneous third ventriculostomies were identified. Head circumference (SE = 8.07; P < 0.001) and average ventricular volume were greater (left: SE = 1.47, P < 0.001) in patients with spontaneous third ventriculostomies when compared with patients without spontaneous third ventriculostomies. Patients with spontaneous third ventriculostomies also had more delayed development in adaptive (difference = 0.2, P < 0.01), gross motor (difference = 0.0, P < 0.01), and fine motor (difference = 0.1, P < 0.001) function.

CONCLUSIONS

Spontaneous third ventriculostomies, likely in the context of increased intracranial pressure, were identified in patients with Krabbe disease. Although difficult to assess, our study highlights the importance of monitoring for increased intracranial pressure, which can result in spontaneous third ventriculostomies, in patients with infantile Krabbe disease.

Peripheral neuropathy in metachromatic leukodystrophy: current status and future perspective

Metachromatic leukodystrophy (MLD) is an autosomal recessively inherited metabolic disease characterized by deficient activity of the lysosomal enzyme arylsulfatase A. Its deficiency results in accumulation of sulfatides in neural and visceral tissues, and causes demyelination of the central and peripheral nervous system. This leads to a broad range of neurological symptoms and eventually premature death. In asymptomatic patients with juvenile and adult MLD, treatment with allogeneic hematopoietic stem cell transplantation (HCT) provides a symptomatic and survival benefit. However, this treatment mainly impacts brain white matter, whereas the peripheral neuropathy shows no or only limited response. Data about the impact of peripheral neuropathy in MLD patients are currently lacking, although in our experience peripheral neuropathy causes significant morbidity due to neuropathic pain, foot deformities and neurogenic bladder disturbances. Besides, the reasons for residual and often progressive peripheral neuropathy after HCT are not fully understood. Preliminary studies suggest that peripheral neuropathy might respond better to gene therapy due to higher enzyme levels achieved than with HCT. However, histopathological and clinical findings also suggest a role of neuroinflammation in the pathology of peripheral neuropathy in MLD. In this literature review, we discuss clinical aspects, pathological findings, distribution of mutations, and treatment approaches in MLD with particular emphasis on peripheral neuropathy. We believe that future therapies need more emphasis on the management of peripheral neuropathy, and additional research is needed to optimize care strategies.

Electroneurography and Advanced Neuroimaging Profile in Pediatric-onset Metachromatic Leukodystrophy

Context

Metachromatic leukodystrophy (MLD) is a rare autosomal-recessive disorder characterized by demyelination of central and peripheral nervous system. There is scarcity of literature on the electrophysiological aspects of peripheral nerves and the advanced neuroimaging findings in MLD.

Aim

The aim was to study the nerve conduction parameters and advanced neuroimaging findings in patients with MLD.

Materials and Methods

This study is a retrospective analysis conducted, between 2005 and 2016, of 12 patients who had biochemical, histopathological, or genetic confirmation of MLD and disease onset before 18 years of age. The clinical, electroneurography, and the advanced neuroimaging findings were reviewed and analyzed.

Statistical Analysis

The data were presented as percentages or mean ± standard deviation as defined appropriate for qualitative and quantitative variables.

Results

Mean age of onset was 4.84 (±4.60) years and seven patients were males. Eight patients had juvenile MLD and four had late infantile MLD. Clinical presentation of psychomotor regression was more common in infantile MLD (75%), whereas gait difficulty (62.5%) and cognitive impairment (37.5%) were more frequent in juvenile MLD. Nerve conduction study (NCS) revealed diffuse demyelinating sensorimotor peripheral neuropathy in 9 (75%) patients. One patient had a rare presentation with conduction blocks in multiple nerves with contrast enhancement of cauda equina. Diffusion restriction involving periventricular and central white matter was seen in five patients and bilateral globus pallidi blooming was noted in three patients.

Conclusion

This study highlights the utility of NCS and advanced magnetic resonance imaging sequences in the diagnosis of MLD.

Neuroimaging Findings in Lysosomal Disorders: 2018 Update

Lysosomal storage disorders are a heterogeneous group of genetic diseases characterized by defective function in one of the lysosomal enzymes. In this review paper, we describe neuroradiological findings and clinical characteristics of neuronopathic lysosomal disorders with a focus on differential diagnosis. New insights regarding pathogenesis and therapeutic perspectives are also briefly discussed.

Genetic Leukoencephalopathies in Adults

PURPOSE OF REVIEW

More than 100 heritable disorders can present with abnormal white matter on neuroimaging. While acquired disorders remain a more common cause of leukoencephalopathy in the adult than genetic causes, the clinician must remain aware of features that suggest a possible genetic etiology.

RECENT FINDINGS

The differential diagnosis of heritable white matter disorders in adults has been revolutionized by next-generation sequencing approaches and the recent identification of the molecular cause of a series of adult-onset disorders.

SUMMARY

The identification of a heritable etiology of white matter disease will often have important prognostic and family counseling implications. It is thus important to be aware of the most common hereditary disorders of the white matter and to know how to distinguish them from acquired disorders and how to approach their diagnosis.

Enlargement of the brachial plexus on magnetic resonance imaging: a novel finding in adult-onset Krabbe disease

Adult-onset Krabbe disease is an autosomal recessive degenerative leukodystrophy that presents with bilateral corticospinal tract involvement on MRI. Although peripheral nerve involvement is a known manifestation of Krabbe disease, MRI findings of peripheral nerve abnormalities are limited to the cranial nerves and spinal nerve roots. In this case report, we discuss two cases of adult-onset Krabbe disease with brachial plexus enlargement on MRI. Adult-onset Krabbe disease should be included in the differential diagnoses when brachial plexus enlargement and white matter lesions involving corticospinal tracts present simultaneously.

Phenotypic variability of Krabbe disease across the lifespan

Krabbe disease (galactocerebrosidase deficiency) is an inherited leukodystrophy that results in severe neurological defects due to altered myelination. Classically, disease onset is within the first year of life. Juvenile and adult-onset cases may have less classic presentations, making diagnosis difficult and often delayed. Here, we review the literature to demonstrate the hetereogeneity of presenting symptoms across all age groups. We also discuss diagnostic approach, emphasizing variation in biochemical, functional, and genetic results among Krabbe phenotypes. Better understanding of the various Krabbe disease phenotypes is critical to facilitate timely diagnosis and appropriate treatment of this clinically heterogeneous disorder.

Variabilité phénotypique dans la maladie de Krabbe au cours de la vie du patient. La maladie de Krabbe (déficit en galactocérébrosidase) est une leukodystrophie héréditaire qui donne lieu à des déficits neurologiques sévères dus à un trouble de la myélinisation. Chez les cas dont la présentation est classique, la maladie débute au cours de la première année de vie. Si la maladie commence chez un adolescent ou un adulte, le mode de présentation peut-ětre moins classique, ce qui rend le diagnostic difficile et souvent tardif. Nous analysons les articles traitant du sujet pour démontrer l'hétérogénéité des symptômes au moment de la première consultation et ceci dans tous les groupes d'âge. Nous discutons également de l'approche diagnostique en mettant l'emphase sur la variation des résultats biochimiques, fonctionnels et génétiques des différents phénotypes dans la maladie de Krabbe. Une meilleure compréhension des différents phénotypes est cruciale pour faciliter un diagnostic précoce et un traitement approprié de cette maladie dont le mode de présentation clinique est hétérogène.

Thickening of the optic nerves in metachromatic leucodystrophy: A new MRI finding

Krabbe's disease (KD) and metachromatic leucodystrophy (MLD) are both lysosomal storage disorders that share some common MRI features. Amongst the imaging findings useful to distinguish one from the other, optic chiasm/nerves thickening have been described as specific key features for differential diagnosis favouring KD. We report the first case of enlargement of the optic nerves and chiasm described in a patient with genetically confirmed MLD.

Metabolic, endocrine, and other genetic disorders

Metabolic, endocrine, and genetic diseases of the brain include a very large array of disorders caused by a wide range of underlying abnormalities and involving a variety of brain structures. Often these disorders manifest as recognizable, though sometimes overlapping, patterns on neuroimaging studies that may enable a diagnosis based on imaging or may alternatively provide enough clues to direct further diagnostic evaluation. The diagnostic workup can include various biochemical laboratory or genetic studies. In this chapter, after a brief review of normal white-matter development, we will describe a variety of leukodystrophies resulting from metabolic disorders involving the brain, including mitochondrial and respiratory chain diseases. We will then describe various acidurias, urea cycle disorders, disorders related to copper and iron metabolism, and disorders of ganglioside and mucopolysaccharide metabolism. Lastly, various other hypomyelinating and dysmyelinating leukodystrophies, including vanishing white-matter disease, megalencephalic leukoencephalopathy with subcortical cysts, and oculocerebrorenal syndrome will be presented. In the following section on endocrine disorders, we will examine various disorders of the hypothalamic-pituitary axis, including developmental, inflammatory, and neoplastic diseases. Neonatal hypoglycemia will also be briefly reviewed. In the final section, we will review a few of the common genetic phakomatoses. Throughout the text, both imaging and brief clinical features of the various disorders will be discussed.

Spinal Nerve Root Enhancement on MRI Scans in Children: A Review

Spinal nerve root enhancement in pediatric patients is generally nonspecific, and clinical and laboratory correlation is essential. Nerve root enhancement indicates lack of integrity of the blood-nerve barrier. In this review, we will present a range of pediatric conditions that can present with spinal nerve root enhancement including inflammatory, infectious, hereditary, and neoplastic causes. Familiarity with the various pathologic entities associated with spinal nerve root enhancement is important for a concise differential diagnosis in the appropriate clinical setting. This will avoid unnecessary additional investigations.

Metachromatic leukodystrophy: Disease spectrum and approaches for treatment

Metachromatic leukodystrophy is an inherited lysosomal disorder caused by recessive mutations in ARSA encoding arylsulfatase A. Low activity of arylsulfatase A results in the accumulation of sulfatides in the central and peripheral nervous system leading to demyelination. The disease is classified in a late-infantile, juvenile and adult onset type based on the age of onset, all characterized by a variety of neurological symptoms, which eventually lead to death if untreated. There is no curative treatment for all types and stages. This review discusses diagnostic process and efficacy of current and possible future therapies such as hematopoietic stem cell transplantation, enzyme replacement therapy and gene therapy. A systematic evaluation regarding the efficacy of hematopoietic stem cell transplantation and a longer follow up period for gene therapy are needed to come to a general conclusion and improve treatment options for metachromatic leukodystrophy.

Cranial nerve and cervical root enhancement in an infant with polymerase gamma mutation mitochondrial disease

BACKGROUND

Nuclear polymerase gamma (POLG) mutations are the most common cause of inherited mitochondrial disease. POLG mutation diseases have a broad spectrum of clinical manifestations; the lethal infantile form is myocerebrohepatopathy spectrum.

PATIENT

A 4-month-old boy was referred for poor feeding, emesis, failure to thrive, and hypotonia.

RESULTS

Brain computed tomography was normal. Brain magnetic resonance imaging with and without contrast demonstrated bilateral enhancement of cranial nerves III, V-X, and the upper and midcervical nerve roots. Liver biopsy revealed early cirrhosis, steatosis, and focal necrosis. Muscle biopsy did not demonstrate specific abnormalities of mitochondrial morphology or number. Electron transport chain analysis of both fibroblasts and muscle demonstrated deficiencies. Because of suspected mitochondrial depletion disorder, testing was performed for mitochondrial abnormalities including analysis of the POLG gene, which revealed two pathogenic mutations, c.1399G>A (p.A467T) and c.3285C>G (p.S1095R).

CONCLUSIONS

We report abnormal gadolinium enhancement of multiple cranial nerves and cervical nerve roots in an infant with myocerebrohepatopathy spectrum disease whose brain MRI otherwise revealed only mild atrophy. Mitochondrial disease should be included in the differential diagnosis of cranial nerve enhancement. Contrast-enhanced MRI aids in the diagnostic evaluation of infants with developmental delay and suspected neurological disease.

Imaging manifestations of the leukodystrophies, inherited disorders of white matter

The leukodystrophies are a diverse set of inherited white matter disorders and are uncommonly encountered by radiologists in everyday practice. As a result, it is challenging to recognize these disorders and to provide a useful differential for the referring physician. In this article, leukodystrophies are reviewed from the perspective of 4 imaging patterns: global myelination delay, periventricular/deep white matter predominant, subcortical white matter predominant, and mixed white/gray matter involvement patterns. Special emphasis is placed on pattern recognition and unusual combinations of findings that may suggest a specific diagnosis.

Novel diffusion tensor imaging findings in Krabbe disease

BACKGROUND

Krabbe disease is a lysosomal disorder that primarily affects myelin. Diffusion tensor imaging (DTI) provides quantitative information about the white matter organization and integrity. Radial diffusivity (RD) reflects myelin injury selectively.

PURPOSE

To report on quantitative DTI findings (including axial diffusivity (AD) and RD, not previously reported) in two children with Krabbe disease compared to controls.

METHODS

A quantitative region of interest (ROI) based DTI analysis was performed for the patients and age- and gender-matched controls. Fractional anisotropy (FA), mean diffusivity, AD and RD values as well as variation ratios between the patients' and controls' values were calculated for nine brain regions.

RESULTS

Two boys with Krabbe disease were included in this study. DTI data were acquired at the ages of 6.25 years and 6.5 months. For all regions, FA ratios were negative, while RD and MD ratios positive. The most elevated variation ratios were found for RD. Variation ratios were greater in the centrum semiovale, corpus callosum, and middle cerebellar peduncles than in other anatomical regions, especially in the older patient in comparison with the younger patient. The AD ratios, however, were much lower and close to zero.

CONCLUSIONS

DTI allows a quantitative evaluation of white matter damage in Krabbe disease. RD seems to be the most sensitive DTI parameter in agreement with the histopathological findings in Krabbe disease, a primary myelin disorder. This may be important in the early detection of the onset of demyelination.

Krabbe disease in adults: phenotypic and genotypic update from a series of 11 cases and a review

Krabbe disease usually presents as a severe leukodystrophy in early infancy and childhood. From a series of 11 patients and 30 cases previously reported in the literature we describe the clinical, radiological, electrophysiological and genetic features of adult Krabbe disease. Patients diagnosed after the age of 16 years were included in this study. They were further divided into three groups depending on age at symptoms onset: (1) childhood onset cases (n = 7); (2) adolescence onset cases (n = 6) and adult onset cases (n = 28). Overall, 96 % of patients in the adult-onset group presented with signs of pyramidal tracts dysfunction. Spastic paraparesis or tetraparesis became prominent in all cases. A peripheral neuropathy was present in 59 % of cases and was most often demyelinating (80 %). Other clinical signs encompassed dysarthria (31 %), cerebellar ataxia (27 %), pes cavus (27 %), deep sensory signs (23 %), tongue atrophy (15 %), optic neuropathy (12 %), cognitive decline (12 %). Cerebrospinal fluid protein concentration was moderately increased in 54 % of patients. Patients in the adolescent- and childhood-onset groups had similar presentations but were more likely to display optic neuropathy (33 % and 57 %) and cerebellar ataxia (50 % and 57 %). In the adult-onset group, the disease progressed slowly over more than 10 years, but a rapid course was observed in two patients. Abnormalities of brain MRI was similar in the three groups and included high signals of cortico-spinal tracts (94 % of cases), hyper-intensities of optic radiations (89 %) and hyper-intensities or atrophy of the posterior part of the corpus callosum (60 %). No clear genotype-phenotype relationship could be demonstrated.

Missense mutation in mouse GALC mimics human gene defect and offers new insights into Krabbe disease

Krabbe disease is a devastating pediatric leukodystrophy caused by mutations in the galactocerebrosidase (GALC) gene. A significant subset of the infantile form of the disease is due to missense mutations that result in aberrant protein production. The currently used mouse model, twitcher, has a nonsense mutation not found in Krabbe patients, although it is similar to the human 30 kb deletion in abrogating GALC expression. Here, we identify a spontaneous mutation in GALC, GALCtwi-5J, that precisely matches the E130K missense mutation in patients with infantile Krabbe disease. GALCtwi-5J homozygotes show loss of enzymatic activity despite normal levels of precursor protein, and manifest a more severe phenotype than twitcher, with half the life span. Although neuropathological hallmarks such as gliosis, globoid cells and psychosine accumulation are present throughout the nervous system, the CNS does not manifest significant demyelination. In contrast, the PNS is severely hypomyelinated and lacks large diameter axons, suggesting primary dysmyelination, rather than a demyelinating process. Our data indicate that early demise is due to mechanisms other than myelin loss and support an important role for neuroinflammation in Krabbe disease progression. Furthermore, our results argue against a causative relationship between psychosine accumulation, white matter loss and gliosis.

Magnetic resonance spectroscopy in metabolic disorders

Magnetic resonance spectroscopy (MRS) is a powerful clinical tool for investigating the metabolic characteristics of neurologic diseases. Proton ((1)H)-MRS is the most commonly used and widely available method. In this article, a brief introduction regarding technical issues of (1)H-MRS applied to the study of metabolic diseases is followed by a description of findings in some of the most common entities in this large, heterogeneous group of neurologic disorders. The aim was to provide a focused representation of the most common applications of (1)H-MRS to metabolic disorders in a routine clinical setting.