Proton MR spectroscopy of basal ganglia in Wilson's disease: case report and review of literature

Brain magnetic resonance spectroscopy (MRS) as a diagnostic tool for detecting early neurological changes in children with Wilson's disease

PURPOSE

Although brain magnetic resonance spectroscopy (MRS) imaging findings in adult Wilson disease (WD) have been explained in extensive details, a paucity of information currently exists regarding brain MRS imaging findings in pediatric WD. The purpose of this study was to clarify the role of brain MRS in detecting early metabolite abnormalities in children with WD.

PATIENT AND METHODS

A case-controlled prospective study included 26 children with WD and 26 healthy controls. All children were subjected to examination on a 1.5 T MRI scanner. The spectra of N-acetyl aspartate (NAA), choline (Cho), and creatine (Cr), as well as the metabolite ratios of NAA/Cho, NAA/Cr, and Cho/Cr, were measured and compared between two groups.

RESULTS

Eight patients revealed increased signal intensity in the basal ganglia at T1-weighted images. When compared with healthy controls, WD patients showed a significant decrease (p <  0.05) in NAA (63.8 ± 9.6 vs 97.6 ± 3.8), Cho (46.7 ± 8.9 vs 87.3 ± 4.7), Cr (44 ± 10.1 vs 81.9 ± 4.05), NAA/Cho (1.92 ± 1.2 vs 3.34 ± 0.55), NAA/Cr (1.29 ± 0.7 vs 2.46 ± 0.34), and Cho/Cr (0.78 ± 0.4 vs 2 ± 0.13). Patients complicated with liver cell failure showed a significant decrease in all previous parameters (p <  0.05) than patients without complications. Patients with mixed neurological and hepatic diseases showed a severe reduction in NAA, NAA/Cr, and NAA/Cho compared with patients with hepatic disease only.

CONCLUSION

MRS in pediatric WD detects early neurological changes even with normal MRI.

A model-based analysis of physiological properties of the striatal medium spiny neuron

As the principal cell of the striatum, medium spiny neurons (MSNs) are closely associated with various motor dysfunctional diseases. In this paper, we describe an electric compartment model constructed in NEURON with a realistic morphology. Based on a 554-compartment computational model, we researched the influence of external current stimuli, different ions conductance, and the removal of partial dendrites on the physiological properties of the MSN. The main results are the following: (1) in the case of external current stimuli, various firing patterns appear in the MSN and the model produces a clear period-adding bifurcation phenomenon; (2) the effect of distinct types of ion channels vary and significant differences in discharge rhythm exist even among ion channels of the same type; (3) the closer the removed dendrite was to the soma, the larger the impact this had on the discharge pattern of the MSN.

Wilson's disease

In the almost 100 years since Wilson's description of the illness that now bears his name, tremendous advances have been made in our understanding of this disorder. The genetic basis for Wilson's disease - mutation within the ATP7B gene - has been identified. The pathophysiologic basis for the damage resulting from the inability to excrete copper via the biliary system with its consequent gradual accumulation, first in the liver and ultimately in the brain and other organs and tissues, is now known. This has led to the development of effective diagnostic and treatment modalities that, although they may not eliminate the disorder, do provide the means for efficient diagnosis and effective amelioration if carried out in a dedicated and persistent fashion. Nevertheless, Wilson's disease remains both a diagnostic and treatment challenge for physician and patient. Its protean clinical manifestations make diagnosis difficult. Appropriate diagnostic evaluations to confirm the diagnosis and institute treatment can be confusing. In this chapter, the clinical manifestations, diagnostic evaluation, and treatment approaches for Wilson's disease are discussed.

Wilson's disease: (31)P and (1)H MR spectroscopy and clinical correlation

INTRODUCTION

Proton ((1)H) magnetic resonance spectroscopy (MRS) changes are noted in Wilson's disease (WD). However, there are no studies regarding membrane phospholipid abnormality using (31)P MRS in these patients. We aimed to analyze the striatal spectroscopic abnormalities using (31)P and (1)H MRS in WD.

METHODS

Forty patients of WD (treated, 29; untreated,11) and 30 controls underwent routine MR image sequences and in vivo 2-D (31)P and (1)H MRS of basal ganglia using an image-selected technique on a 1.5-T MRI scanner. Statistical analysis was done using Student's t test.

RESULTS

The mean durations of illness and treatment were 6.2 ± 7.4 and 4.8 ± 5.9 years, respectively. MRI images were abnormal in all the patients. (1)H MRS revealed statistically significant reduction of N-acetyl aspartate (NAA)/choline (Cho) and NAA/creatine ratios in striatum ((1)H MRS) of treated patients compared to controls. The mean values of phosphomonoesters (PME) (p < 0.0001), phosphodiesters (PDE) (p < 0.0001), and total phosphorus (TPh) (p < 0.0001) were elevated in patients compared to controls. Statistically significant elevated levels of ratio of PME/PDE (p = 0.05) observed in the striatum were noted in treated patients as compared to controls in the (31)P MRS study. The duration of illness correlated well with increased PME/PDE [p < 0.001], PME/TPh [p < 0.05], and PDE/TPh [p < 0.05] and decreased NAA/Cho [p < 0.05] ratios. There was correlation of MRI score and reduced NAA/Cho ratio with disease severity. The PME/PDE ratio (right) was elevated in the treated group [p < 0.001] compared to untreated group.

CONCLUSIONS

There is reduced breakdown and/or increased synthesis of membrane phospholipids and increased neuronal damage in basal ganglia in patients with WD.

MR Spectroscopy of Metabolic Disorders

The application of MR spectroscopy (MRS) in pediatric brain disorders yields valued information on pathologic processes, such as ischemia, demyelination, gliosis, and neurodegeneration. Because these processes manifest in inborn errors of metabolism, the purposes of this article are to (1) describe the spectral changes that are associated with the relatively common metabolic disorders, with summaries of known spectroscopic features of these disorders; (2) offer suggestions for recognition and distinction of disorders; and (3) provide general guidelines for MRS implementation. Although many conditions have a similar presentation, MRS offers valuable information for the individual patient in diagnosis and therapy when integrated fully into the clinical setting.

Acute putaminal necrosis and white matter demyelination in a child with subnormal copper metabolism in Wilson disease: MR imaging and spectroscopic findings

Wilson disease (WD) that manifests solely with acute and severe neurological damage in the absence of hepatic disease and Kayser-Fleischer ring of the cornea is rare and difficult to diagnose at the acute setting. This report describes unusual diffusion and proton spectroscopic magnetic resonance (MR) imaging findings in a 12-year-old boy with WD who presented with hemichorea and subnormal copper metabolism. The MR imaging findings of lactate accumulation, decrease of N-acerylaspartate/creatinine (NAA/Cr) ratio and markedly increased apparent diffusion coefficient (ADC) value of the asymmetrical edematous putaminal lesions in the early stage were suggestive of acute necrosis with anaerobic metabolism of glucose leading to poor clinical outcome at follow-up.

Region and volume dependencies in spectral line width assessed by 1H 2D MR chemical shift imaging in the monkey brain at 7 T

High magnetic fields increase the sensitivity and spectral dispersion in magnetic resonance spectroscopy (MRS). In contrast, spectral peaks are broadened in vivo at higher field strength due to stronger susceptibility-induced effects. Strategies to minimize the spectral line width are therefore of critical importance. In the present study, 1H 2D chemical shift imaging at short echo times was performed in the macaque monkey brain at 7 T. Large brain coverage was obtained at high spatial resolution with voxel sizes down to 50 microl being able to quantify up to nine metabolites in vivo with good reliability. Measured line widths of metabolites decreased from 14.2 to 7.6 Hz with voxel volumes of 3.14 ml to 50 microl (at increased spatial resolution). The line width distribution of the metabolites (7.6+/-1.6 Hz, ranging from 5.5 to 10 Hz) was considerably smaller compared to that of water (10.6+/-2.4 Hz) and was also smaller than reported in 1H MRS at 7 T in the human brain. Our study showed that even in well-shimmed areas assumed to have minimal macroscopic susceptibility variations, spectral line widths are tissue-specific exhibiting considerable regional variation. Therefore, an overall improvement of a gross spectral line width--directly correlated with improved spectral quality--can only be achieved when voxel volumes are significantly reduced. Our line width optimization was sufficient to permit clear glutamate (Glu)-glutamine separation, yielding distinct Glu maps for brain areas including regions of greatly different Glu concentration (e.g., ventricles vs. surrounding tissue).