We present six proven cases of chordoma of the clivus studied by CT and MRI, with special attention to the extent of the tumour and to the signal intensity after intravenous gadolinium. MRI is the best technique for assessing the extent of the tumour but CT is important for showing osteolysis. Our aim was to determine differential diagnostic neuroradiological criteria. Reliable signs of chordoma of the skull base are: posterior extension to the pontine cistern; a lobulated, "honeycomb" appearance after gadolinium: the swollen appearance of the bone in the early stages; bone erosion on CT and frequent extension to critical structures such as the circle of Willis, cavernous sinuses and brain stem.

Our aim was to investigate the corticospinal tracts (CST) in motor neurone disease, using MRI, and to correlate findings with clinical data. We studied 31 patients with amyotrophic (ALS) and eight with primary lateral sclerosis (PLS). The signal from the CST was classified into four grades on T2-weighted images, and compared to T2-weighted images of 37 age-matched control subjects. No abnormalities were seen in the CST on T1-weighted images and were rarely evident on proton-density weighting. Variable high signal in the CST was found on T2-weighted images in 35 patients, and in 29 control subjects. Our grades 0 and 1 were more frequent in control subjects, grades 2 and 3 more frequent in patients. We found no correlation between the high signal and clinical data, including the duration of the illness. We therefore conclude that this technique is neither sensitive nor specific except in grade 3 which is quite specific for ALS. In half the patients we found atrophy of the superior parietal gyrus, which merits further study.

We evaluated periradicular injection of corticosteroids performed by neuroradiologists under fluoroscopic guidance in the treatment of lumbosacral nerve root pain in 40 patients (average age 48 years) presenting with lumbosciatica or radiculopathy not responding to conservative treatment. Patients with root pain due to infectious, neoplastic or inflammatory diseases were excluded, as were patients who needed immediate surgery. Pain was evaluated using a visual analogue scale (VAS) 10 and 90 days after the injection. After 10 days a substantial decrease in root pain was observed, with a statistically significant decrease in mean VAS. This decrease was observed in 90% of patients, and it persisted after 90 days in 85%. Side effects were rare, mild and disappeared spontaneously. They were related to the drug injected (corticosteroids).

The bipolar defects observed in schizencephalies-clefts in the hemispheric mantle on the one hand, absent septum pellucidum on the other--without any anatomic or functional continuity suggest that there is some sort of common specific vulnerability of both structures. A study of the correlation between lobar location of the clefts and involvement of the septum pellucidum was undertaken, considering the hypothesis that the septum pellucidum is the portion of a "medial medullary velum" that corresponds to the frontal lobe, while the psalterium would correspond to the parieto-occipital lobe and the fimbria corresponds to the temporal lobe. This retrospective study of 16 cases of schizencephaly properly investigated by MR discloses a perfect correlation, all cases with absent septum pellucidum having clefts into the frontal lobe, all cases with present septum pellucidum having clefts in the parietal, temporal, and occipital lobes, and only the few instances (3 cases) of overlapping findings being characterized by clefts in the central area, where the distinction between posterior frontal and anterior parietal lobes is uncertain because of the cortical dysplasia related to the clefts. Partial defects of the septum also proved to correlate closely, topographically, with the location of the clefts. Therefore, the facts confirm a segmental organization of the mantle and septal defects, suggesting a developmental rather than a destructive mechanism, which could at least be related to a segmental pattern of selective vulnerability.

We report the case of a young patient with neurocutaneous melanosis (NCM) who presented with temporary aphasia and right hemiparesis followed by progressive coma and death. To our knowledge, this is the first case of this disease examined by CT, MRI, angiography and in which an autopsy was performed to assert the diagnosis with histology. Besides, we discuss differential diagnoses and interest of MRI for early diagnosis.

Our purpose was to compare prospectively the sensitivity of contrast-enhanced magnetisation transfer (MT) MRI and gradient-echo (GE) T1-weighted images in metastatic disease of the brain. We studied 52 patients with brain metastases, using conventional T1-weighted GE and MT spin-echo (SE) images after the same standard dose of gadolinium. Axial 5-mm reconstructions of GE data were compared with 5-mm MT images in the same plane. Metastases were counted independently by two neuroradiologists. In 12 patients (23%) MT imaging showed more metastases than GE images (P = 0.03). We detected 68 more metastases with the former technique.

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