Brain MRI in mucopolysaccharidosis: effect of aging and correlation with biochemical findings.

OBJECTIVE: To investigate the influence of aging on conventional MRI and magnetic resonance spectroscopy (MRS) findings of mucopolysaccharidosis (MPS) patients and to test the correlation of enzyme levels, urinary glycosaminoglycans (GAG), and neuroimaging findings. METHODS: Sixty patients with MPS types I (n = 8), II (n = 31), IV-A (n = 4), and VI (n = 17) underwent T2, fluid-attenuated inversion recovery (FLAIR), and MRS of the brain. For analysis of MRI variables, we measured the normalized cerebral volume (NCV), CSF volume (NCSFV), ventricular volume (NVV), and lesion load (NLL) on FLAIR using semiautomated and automated segmentation techniques. For MRS, a point-resolved spectroscopy technique was used. Voxels were positioned at the white and gray matter. Statistical analysis involved Pearson or Spearman tests for correlation between neuroimaging, age, enzyme levels, and urinary GAG. RESULTS: The median age at onset of the disease was 20 months. Patients with longer disease duration had more NLL in the white matter (r = 0.28, p = 0.03), and this difference was more pronounced in MPS II patients (r = 0.44, p = 0.02). Metabolites ratios in MRS, NCV, NCSFV, and NVV did not correlate with disease duration or age of the patients (p > 0.05). MRI and MRS variables in either the white or the gray matter did not correlate with enzymatic activity or GAG levels. Patients with MPS II had a lower mean NCV (p < 0.001). CONCLUSIONS: Our data showed that white matter lesion is more extensive as disease duration increases, especially in mucopolysaccharidosis type II patients. MRI and magnetic resonance spectroscopy findings did not correlate with either enzymatic or glycosaminoglycan levels.

Correlation of MR imaging and MR spectroscopy findings with cognitive impairment in mucopolysaccharidosis II.

BACKGROUND AND PURPOSE: There are no reliable markers to predict neurologic outcome of patients with mucopolysaccharidosis (MPS) II. We hypothesized that brain MR imaging and MR spectroscopy are useful in depicting features related to cognitive impairment (CI) in MPS II. MATERIALS AND METHODS: Nineteen male patients with MPS II were included in this study. They were evaluated through intelligence/developmental tests to be classified in 2 groups: patients with CI (group A) or patients without CI (group B). Brain MR imaging evaluated white matter (WM) lesions, hydrocephalus, and brain atrophy. Voxels from MR spectroscopy (point-resolved spectroscopy TE 30 ms) were positioned in the WM of the deep right frontal lobe and at the gray matter (GM) in the posterior occipital cortex across the midline. Comparison of MR imaging and MR spectroscopy findings between these 2 groups and a control group was performed. RESULTS: The mean age of the patients was 9.6 years (group A, 7.08 years old, 12 patients; group B, 14 years old, 7 patients; P = .076). Brain atrophy and hydrocephalus were more frequently found in group A patients (P=.006 and P=.029, respectively); these patients also presented more severe WM lesions than patients from group B (P=.022). Patients from group A also had a higher myo-inositol (mIns)/creatine (Cr) ratio in the GM (P=.046) and in the WM (P=.032). The choline/Cr and N-acetylaspartate/Cr ratios were similar in both groups. CONCLUSIONS: Our study showed that severe WM lesions, brain atrophy, hydrocephalus, and elevated mIns/Cr were more common in patients with MPS II and with CI.

What is the variability between 2 consecutive cystometries in the same child?

PURPOSE: We compared the results of 2 cystometrograms (CMGs) performed during a single session in the same child to determine the variability between consecutive cystometries. MATERIALS AND METHODS: Subjects underwent 2 consecutive bladder fillings performed at the same rate and position. Maximum cystometric bladder capacity (CBC), pressure at CBC, leak point pressure, maximum flow rate, pressure at maximum flow, maximum voiding pressure, residual urine and pressure specific volumes (PSV) less than 20, 30 and 40 cm water were compared between studies. Uninhibited detrusor contractions (UICs), defined by the previous and new International Children's Continence Society definitions of UIC, were also compared. Data were analyzed using paired t test, chi-square and interclass correlation. RESULTS: CMGs in 32 male and 34 female children were available for analysis. Mean subject age was 7.4 years (range 1 month to 18 years). Of the children 43 (65%) had spinal dysraphism, 4 (6%) had cerebral palsy, 5 (8%) had posterior urethral valves, and 14 (21%) had recurrent urinary tract infection, daytime incontinence and frequency/urgency symptoms. Maximum CBC, pressure at CBC, leak point pressure, maximum flow rate, pressure at maximum flow, maximum voiding pressure and residual urine did not differ between the 2 studies. PSVs less than 20, 30 and 40 cm water were highly correlated between the 2 CMGs (interclass correlation coefficients 0.795, 0.683 and 0.850, respectively). There were more UICs on the first than the second study (p = 0.02 and 0.03) as defined by the previous and new definitions of UIC. UIC threshold volume was less on the first CMG (p = 0.00 and 0.03). UICs were either present or absent on both studies in 56 of the 66 (85%) children by the previous UIC definition and in 51 (77%) by the new UIC definition. CONCLUSIONS: There is no difference in CBC, PSV and pressure flow parameters when performing consecutive urodynamic studies in the same child. However, UICs are more frequent on the first study. We conclude that repeat cystometry is not indicated in the absence of UICs on the first study and suggest that the second consecutive CMG be used for clinical interpretation when repeat studies are performed in the same session.

Protective role of brain ascorbic acid content against lipid peroxidation.

The high ascorbic acid concentration in the brain inhibits lipid peroxidation induced by various agents in rat brain microsomes. The physiological importance of the fact is discussed.