Cerebral MRI in two brothers with mucopolysaccharidosis type I and different clinical phenotypes

Mucopolysaccharidoses type I and II: new neuroimaging findings in the cerebellum

BACKGROUND

The neuroimaging literature on mucopolysaccharidoses (MPS) is focusing mostly on supratentorial findings. Our study aims to extend the spectrum of neuroimaging findings in patients with MPS focusing on the cerebellum.

METHODS

Twelve patients were included (7 MPS type I and 5 MPS type II). The median age at last MRI was 9.9 years (mean age 10.1 years, range 1.8-28.8 years). All available brain MR images were retrospectively evaluated for infratentorial and supratentorial abnormalities with semiquantitative analysis and qualitative evaluation.

RESULTS

Infratentorial findings included enlarged perivascular spaces (PVS) in the cerebellum in 7/12, mega cisterna magna in 3/12 and macrocerebellum in 2/12 patients. Enlarged cerebellar PVS developed later than those in the supratentorial brain and showed mild changes in size over time. The macrocerebellum developed progressively and seems to be caused by a thickening of the cortical cerebellar gray matter. Enlarged PVS in the brain stem were found in 10/12 patients. Supratentorial findings included enlarged PVS in all patients. Ventriculomegaly and white matter signal abnormalities were noted in 8/12, cerebral atrophy in 7/12 patients.

CONCLUSION

Involvement of the posterior fossa structures in MPS I and II is not uncommon. Our study revealed two neuroimaging findings that have not been previously described in MPS: enlarged PVS in the cerebellum and a macrocerebellum. The pathogenesis and clinical significance of these new findings remain unclear and should be assessed in a larger cohort of patients.

Brain and spinal MR imaging findings in mucopolysaccharidoses: a review

MPS represents a group of rare hereditary disorders characterized by multisystem involvement due to intralysosomal GAG accumulation. Among various tissues, both the central and peripheral nervous system are affected in almost all types of the disease. Thus, brain and spinal MR imaging are valuable tools for the assessment of neurologic involvement, and there is evidence that they might be reliable markers demonstrating disease severity and efficacy of treatment options currently used in patients with MPS. We aimed to review the most prominent MR imaging features of patients with MPS, paying attention to the physiopathologic mechanisms responsible for these alterations. Along with the description of neuroimaging findings, existing data in relation to their correlation with the severity of neurologic involvement is discussed, while another topic of great importance is the effect of various therapeutic regimens in the progression of brain and spinal MR imaging alterations. Finally, recent data concerning MR spectroscopy studies in MPS are also critically discussed.

Decreased T2 signal in the thalami may be a sign of lysosomal storage disease

INTRODUCTION

Lysosomal disorders are rare and are caused by genetically transmitted lysosomal enzyme deficiencies. A decreased T2 signal in the thalamus has occasionally been reported.

AIMS

Because the finding of bilateral abnormal signal intensity of the thalamus on T2-weighted images has not been systematically reviewed, and its value as a diagnostic tool critically evaluated, we carried out a systematic review of the literature.

METHODS

Articles in English with 30 trios of keywords were collected from PubMed. Exclusion criteria were lack of conventional T2-weighted images in the protocol and not being a human study. Finally, 111 articles were included. The thalamus was considered affected only if mentioned in the text or in the figure legends.

RESULTS

Some 117 patients with various lysosomal diseases and five patients with ceruloplasmin deficiency were reported to have a bilateral decrease in T2 signal intensity. At least one article reported a bilateral decrease in signal intensity of the thalami on T2-weighted images in association with GM1 and GM2 gangliosidosis and with Krabbe's disease, aspartylglucosaminuria, mannosidosis, fucosidosis, and mucolipidosis IV. Furthermore, thalamic alteration was a consistent finding in several types of neuronal ceroid lipofuscinosis (NCL) including CLN1 (infantile NCL), CLN2 (classic late infantile NCL), CLN3 (juvenile NCL), CLN5 (Finnish variant late infantile NCL), and CLN7 (Turkish variant late infantile NCL).

CONCLUSION

A decrease in T2 signal intensity in the thalami seems to be a sign of lysosomal disease.

Virchow-Robin spaces on magnetic resonance images: normative data, their dilatation, and a review of the literature

INTRODUCTION

Virchow-Robin spaces (VRS) are perivascular spaces in the brain and can be visualized on magnetic resonance images (MRI). We attempt to provide a better understanding of the significance of VRS for pathological and physiological processes by reviewing the literature, presenting normative data for the first time, and proposing a definition for the dilatation of the VRS on MRI that is based on shape rather than size.

METHODS

We evaluated the VRS in 125 healthy subjects (age range 1-30 years) using high-resolution 3D images, and in 36 patients (age range 2-16 years) with normal MRI, using routine clinical sequences.

RESULTS

VRS were visible in all high-resolution images of the 125 healthy subjects. Two of them revealed dilated VRS, giving a prevalence of 1.6%. VRS could be visualized in 29 (80%) of the 36 paediatric clinical scans; none was dilated. It was demonstrated that the visibility of VRS on MRI is sequence-dependent.

CONCLUSION

From the results of this study and the literature on the nature and pathology of VRS, we conclude that VRS on MR images of healthy individuals are normal findings, even if they are dilated. A judgement on whether dilated VRS in an individual patient is a normal variant or part of a disease process can be made by taking into account the appearance of the adjacent tissue on MRI and the clinical context.

Correlation between cerebral MRI abnormalities and mental retardation in patients with mucopolysaccharidoses

Mucopolysaccharidoses (MPSs) are a group of inherited disorders due to lysosomal enzyme deficiencies which lead to multi-organ accumulation of glycosaminoglycans. Some forms of MPS disorders are characterized by various degrees of mental retardation. Magnetic Resonance Imaging (MRI) is the primary imaging technique to detect CNS alterations. The aim of this study is to evaluate the correlation between white matter (WM) alterations and the presence of mental retardation. We analyzed 20 patients with different forms of MPSs, 11 with mental retardation and 9 with a normal cognitive function; all of them underwent brain MRI and received a score on the basis of the alterations (WM alterations; perivascular, subarachnoid, and ventricular space enlargement; abnormalities of the basal ganglia, of the corpus callosum and of the atlanto-axial joint). All patients with mental retardation presented severe WM alterations, while only five out of the nine subjects without mental retardation showed certainly WM abnormalities. As far as the other cerebral abnormalities are concerned, no difference between the two groups has been found. These data seem to show that there is a significant correlation between the presence of WM alterations and mental retardation.

White matter changes mimicking a leukodystrophy in a patient with Mucopolysaccharidosis: characterization by MRI

Mucopolysaccharidosis (MPS) type I (alpha-iduronidase deficiency) is characterized by storage and massive urinary excretion of dermatan sulfate and heparan sulfate; it may be distinguished into three different subtypes based on age at onset and severity of the clinical symptoms. We report on progressive white matter involvement documented by serial MR imaging in a patient with the MPS type I, severe skeletal involvement and preserved mental capabilities (intermediate phenotype or Hurler/Scheie syndrome).The natural history of white matter abnormalities in patients with MPS is still unclear; based on the present study, it appears that degenerative changes of the white matter mimicking a leukodystrophy may mark the course of MPS type I. We also suggest that the degree of MR changes in patients with MPS does not always reflect their neurological impairment.

Brain magnetic resonance imaging in 23 patients with mucopolysaccharidoses and the effect of bone marrow transplantation

A longitudinal study of cranial magnetic resonance imaging (MRI) was carried out in 23 patients with mucopolysaccharidoses (MPS); 1 each of types IH, VI, and VII; 2 of type IS; 10 of type II; and 4 each of types IIIB and IVA. Six types of distinct abnormalities were 1) cribriform changes or spotty changes in the corpus callosum, basal ganglia, and white matter; 2) high-intensity signal in the white matter on T2-weighted image; 3) ventriculomegaly; 4) diffuse cerebral cortical atrophy; 5) spinal cord compression; and 6) megacisterna magna. The cribriform changes that corresponded to dilated perivascular spaces were found in the patients with MPS IS, II, and VI. The patchy and diffuse intensity changes were found in the patient with MPS II and IIIB, respectively. MPS IH and the severe type of MPS II showed marked ventriculomegaly. Marked cerebral atrophy was observed in all MPS IIIB patients and in the severe type of MPS II patients. Spinal cord compression was a feature usually observed in MPS IH, IVA, VI, and VII. Megacisterna magna was frequent in the patients with MPS II (6/10). In two of five patients, the therapeutic effect of bone marrow transplantation (BMT) was remarkable. Both the cribriform changes and the intensity change of the white matter in a MPS VI patient disappeared eight years after the BMT. Slight improvement of cribriform change was noted in one patient with MPS II three years after the BMT. MRS was not sufficient to estimate the accumulation of glycosaminoglycans but was useful for evaluating neuronal damages.

Minor cerebral alterations observed by magnetic resonance imaging in syndromic children with mental retardation

OBJECTIVE

To evaluate the anomalies of the central nervous system (CNS) by magnetic resonance imaging (MRI) in normal subjects and in syndromic patients.

METHODS AND MATERIAL

Seventy-three normal subjects and 50 different syndromic patients with mental retardation (from 3 months to 16 years) were studied utilizing several morphometric parameters (degree of myelination of the white matter, evaluation of liquoral spaces, septo-caudate distance, Evans index, Aboulezz method, and length, width and angles of corpus callosum).

RESULTS

A high frequency of anomalies of the corpus callosum, the Chiari anomaly and alterations either of the white matter or of the ventricular and periencephalic system have been observed.

CONCLUSION

The authors point out the importance of cerebral MRI in the study of CNS in patients with malformation syndromes. The present research, carried out on a large number of both normal subjects and patients with malformation syndromes, represents one of the first systematic studies in this field.

MRI in the mild type of mucopolysaccharidosis II (Hunter's syndrome)

We report imaging findings in a 3-year-old boy with the typical mild type of Hunter's disease. MRI revealed multifocal large cyst- or spindle-like areas of increased and decreased signal in the white matter, including the corpus callosum on T1- and T2-weighted images. The white matter showed high signal on T2-weighted images, isointense with cerebrospinal fluid on all other pulse sequences. To our knowledge, these appearances have not been reported in this disorder. Deposition of mucopolysaccharide and/or glycolipid and increase in fluid content seem to be responsible.