Search

Salla disease (SD) is a lysosomal disorder manifesting in infancy with hypotonia, nystagmus, ataxia and retarded motor development. MRI typically shows hypomyelination confined to the cerebral white matter. We describe a patient with two MRI studies in addition to repeated urine examinations. This case was problematic because the first urine examination did not show the elevation of free sialic acid typical of SD and MRI was also atypical, with abnormal signal intensity in cerebellar white matter. We recommend repeated urinary examinations and a search for SLC17A5 mutations in patients with cerebral signal intensity abnormalities typical of SD and emphasise that cerebellar white-matter involvement on MRI does not exclude the diagnosis.

The magnetic resonance images of 67 healthy subjects aged 4-50 years were studied for differences in general signal intensity between the different brain structures, the frequency of focal intensity changes in the brain, and variations in size of the cerebrospinal fluid (CSF) spaces. In adults over 25 years of age the thalamus gave lower signal than the putamen or caudate nucleus. Definite periventricular high signal was found in the white matter of one third of subjects of all ages. Small (< 5 mm in diameter) high signal foci were found in the cerebral white matter on T2-weighted images in 27% of subjects (20% of healthy children and adolescents and 34% of adults). They gave high signal on both short and long echoes in 11% of children and adolescents and in 22% of adults; 51% of all foci gave high signal with both echoes. This does not support the hypothesis that they are caused mainly by enlarged Virchow-Robin spaces. Of the high signal foci on T2-weighted images, 86% were in watershead areas. Two foci were found in one subject in the periventricular watershed area (beside the tips of the frontal horns) and they were never seen in the other deep white matter regions. In healthy, relatively young subjects with no known risk factors, high signal foci other than Virchow-Robin spaces, were common; neither their prevalence nor their number correlated with age in this series. A few slightly large sulci were found in some adults.

Lysosomal disorders are rare and are caused by genetically transmitted lysosomal enzyme deficiencies. A decreased T2 signal in the thalamus has occasionally been reported. 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. 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. 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). A decrease in T2 signal intensity in the thalami seems to be a sign of lysosomal disease.

We examined 66 healthy volunteers aged 4 to 50 years by magnetic resonance imaging (MRI) and the signal intensity was measured on T2-weighted images in numerous sites and correlated with age and sex. Using distilled water and cerebrospinal fluid (CSF) as references on each slice, we calculated the signal intensities of the brain structures. Calculated ratios between structures did not change with age, except for those of the globus pallidus and thalamus, in which the signal intensities decreased more rapidly. The signal intensities of other brain structures changed equally but this could not be discerned visually and quantitative measurements were required. The signal intensities in the white and deep grey matter decreased rapidly in the first decade and then gradually to reach a plateau after the age of 18 years. Maturation of the brain thus seems to continue until near the end of the second decade of life. No sex differences were found. Quantitative analysis requires intensity references. The CSF in the tips of the frontal horns seems to be as reliable as an external fluid reference for intensity, and can be used in routine examinations provided the frontal horns are large enough to avoid partial volume effect.

Our purpose was to document the MRI appearances of the brain in healthy middle-aged to elderly subjects. T2- and proton density-weighted axial slices were obtained in 61 volunteers, 30-86 years of age. After visual inspection, signal intensities of brain structures were measured on T2-weighted images. Age-related changes became increasingly apparent after age 50. The main findings were that signal intensity of the white matter increased concomitantly with widening of the cerebrospinal fluid spaces; that basal ganglia remained stable; that high-signal foci in white matter increased in number and size after the age of 50 years; that periventricular high-signal foci were constant after the age of 65 years. Our visual impression of a decrease in signal intensity of the central grey matter with age seems to be mistaken. Pathological processes should be suspected if periventricular foci are found in middle-aged or young subjects.

Postmortem MRI was carried out on the formalin-fixed brains of 14 patients with juvenile (JNCL) and two with late infantile neuronal ceroid lipofuscinosis, one of variant and the other of classical type. Two patients with JNCL had also undergone MRI during life. After MRI, specimens for histopathological analysis were taken from standard areas of the cerebral cortex, deep nuclei and white matter. The signal intensity of the periventricular white matter was usually higher than that of the peripheral white matter, a finding which correlated with the severe periventricular loss of myelin and gliosis observed histologically. The signal intensity was usually lower in the thalamus than in the putamen; in some patients the signal intensity of the thalamus was equal to or even lower than that of the white matter. However, myelin loss, gliosis, the storage process or neuronal loss in the thalamus did not correlate with the MRI findings. Since in one patient with JNCL the ante- and postmortem MRI did not differ basically, it appears probable that the periventricular changes detected in vivo on MRI are due to the severe loss of myelin and gliosis observed in this study. However, changes resulting from the fixation process must be considered, when postmortem and in vivo MRI are correlated.

We studied 30 patients with juvenile neuronal ceroid lipofuscinosis (JNCL). The patients (aged 6–25 years) and 43 age-matched healthy volunteers underwent MRI. After visual assessment, the signal intensity was measured on T2-weighted images in numerous locations. The thickness of the cortex and corpus callosum and the dimensions of the brain stem were measured. Mild to moderate cerebral atrophy was found in 14 of 30 patients, most of them over 14 years of age; 5 older patients had mild to moderate cerebellar atrophy. There was reduction in the size of the corpus callosum and brain stem. The thalamus, caudate nucleus and putamen appeared to give low signal in patients from the ages of 7, 11 and 11 years, respectively. In contrast, the signal intensity measured from the thalamus in these patients showed only a slight (insignificant) decrease compared with controls. The most significant alteration, an increase in measured signal intensity, was found in the white matter (P

Our purpose was to develop a method of measuring the size of the brain stem by routine MRI and to determine brain stem dimensions in a normal population. We examined 174 subjects, aged 4 months to 86 years, with no known brain disease. Sagittal midline diameters of the mesencephalon, pons and medulla oblongata were measured on sagittal T1-weighted images, coronal diameters from axial T2-weighted images. The adult midsagittal diameter of the mesencephalon was reached at the age of 6 years, and decreased slightly after 45-50 years. Pontine dimensions increased until the age of 20 years and did not subsequently decrease. The midsagittal and midcoronal diameters of the medulla oblongata stopped increasing at the ages of 6 and 8 years, respectively. Minimal reduction in the midsagittal diameter occurs after 50 years. Normal ranges for each dimension were recorded. Knowledge of the normal variation in size of the brain stem can be helpful in the investigation of neurodegenerative diseases. The method described is rapid and needs no additional hard- or software. An additional finding was an increase in large vermian sulci in subjects over 50 years of age.