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Biomedical subjects

P Maeder

Publications and source records attributed to P Maeder.

71 records · Page 4Linked to original sources
PubMed1992

Cranial CT and MRI in malignant phenylketonuria.

Malignant phenylketonuria is a rare disease caused by a deficiency in dihydropteridine-reductase which induce a hyperphenylalaninemia and a deficiency of neurotransmitters such as 3,4,dihydroxyphenylalanine (DOPA) and 5 hydroxytryptophan. The case of a patient with malignant phenylketonuria (PKU) who underwent both CT and MR Imaging is reported. CT demonstrated the characteristic calcifications of the basal ganglia. MRI demonstrated areas of hypersignal on T1 images in the basal ganglia, subcortical frontal and occipital white matter and cortex probably corresponding to calcifications. The MR findings are not specific but could be useful in monitoring the diet and neurotransmitter substitution therapy.

Brain↗
PubMed1991

Acute pseudobulbar or suprabulbar palsy.

We studied 13 patients with supranuclear lower cranial nerve ("pseudobulbar" or "suprabulbar") palsy of acute onset. While seven patients had had a prior stroke, six patients had no history of stroke. Eight patients experienced a complete bilateral supranuclear lower cranial nerve palsy, which was isolated in five patients and associated with hemiplegia and with hemiparesis in three patients. Pseudobulbar palsy was partial in five patients. Only one patient had neuropsychologic impairment. The pseudobulbar features improved or recovered within a few weeks in all patients. The common characteristic of the lesions on computed tomography or magnetic resonance imaging was the interruption of the corticonuclear pathways contrasting with marked sparing of the corticospinal pathways in both hemispheres. These lesions were either an opercular infarct, or a deep infarct in the corona radiata or internal capsule, or a lenticular hemorrhage. Hypertension was the most prevalent concomitant. Our findings suggest that acute pseudobulbar or suprabulbar palsy has rather stereotyped anatomic-vascular correlates and time course.

Acute Disease↗
PubMed1991

Early spontaneous hematoma in cerebral infarct: is primary cerebral hemorrhage overdiagnosed?

We identified 15 patients (63 +/- 8 years) in whom CT showed no bleeding within 6 hours of stroke onset but showed ganglionic or lobar hemorrhage less than 18 hours later, without visible underlying infarct (early spontaneous intra-infarct hematoma [ESIH]). No patient had antithrombotic therapy or a coagulation disorder, but eight had hypertension. The second CT was prompted by rapid worsening (in 10) or because the first CT was not available (in five). Prior transient ischemic attacks, silent infarcts on CT, and a potential cardiac source of embolism were more common in patients with ESIH than in 200 patients with primary cerebral hemorrhage (PCH) admitted during the same period. Distal occlusions were present in four of five patients who underwent intracranial studies within the first 2 days. Most of these patients probably had embolism with early and extensive bleeding in the ischemic area. Our findings suggest that ESIH may be under-recognized, while PCH may be overdiagnosed.

Aged↗
PubMed1991

Volumes of chronic traumatic frontal brain lesions measured by MR imaging and CBF tomography.

The volumes (ml) of chronic traumatic frontal brain lesions were compared measured "morphologically" with MR imaging (T1 and T2 weighted images) and "functionally" with a tomographic rCBF technique (SPECT with 133Xe i.v.). The T1 volumes varied between 11 and 220 ml. The correlation between T1 and T2 volumes was 0.95, the T2 volumes being 33% larger than T1 volumes (p less than 0.001). The functional SPECT volumes were considerably larger (range 16-324 ml) than the MR volumes. The mean volume difference was 81% between T1 and SPECT images (p less than 0.001), and 35% between T2 and SPECT images (p less than 0.001). Correlations between the MR and SPECT volumes were also higher for T2 than T1 volumes. The volume difference is most likely explained by a functional decrease in regions around the lesion in which no morphologic change visible on MR images had taken place. MR and SPECT volume measurements were positively related to persistent lack of energy and personality changes, but only moderately related to duration of impaired consciousness and neuropsychologic outcome.

Adult↗
PubMed1990

Magnetic resonance imaging of the human lateral geniculate body.

We used magnetic resonance imaging to map the human lateral geniculate body. The optimal imaging plane was determined by obtaining axial and coronal scans in two normal brains obtained at autopsy. The brain specimens were then sectioned and individual slices were compared with matching magnetic resonance images. After the lateral geniculate body was identified using this correlative anatomic approach, the nucleus was imaged in four normal subjects.

Adult↗
PubMed1990

[Traumatic dissection of the internal carotid artery].

Two patients with posttraumatic dissection of the internal carotid artery were referred to the neurosurgical department with secondary neurological deterioration following a minor head injury with concussion. Both developed aphasia and right hemiparesis during the first few hours after the accident; one patient also had right focal seizures. On admission, both were only mildly lethargic, which contrasted with the severity of the focal neurological signs. Early CT scan was normal in both cases, whereas cerebral blood flow (CBF) studies by single photon emission computerized tomography (SPECT) with Tc-HMPAO (Ceretec) showed perfusion defects in the region supplied by the left middle cerebral artery (MCA), correlating with the clinical picture. Doppler sonography disclosed pathologic flow patterns, and carotid angiography demonstrated dissection of the internal carotid artery, in one patient on the left only and in the other bilaterally, with embolic occlusion of a branch of the left MCA in the latter case. Clinical features, pathogenesis, diagnostic workup and possible treatment (medical, as in our two cases, versus surgical) of this rare pathology are briefly reviewed.

Adult↗
PubMed1985

Effects of ageing on local rates of cerebral protein synthesis in Sprague-Dawley rats.

The effects of ageing on local rates of protein synthesis in 39 brain structures in resting conscious rats have been examined. Young adult rats (aged 6 months) have been compared with a group of middle-aged/aged rats (aged 15-23 months). The results show that ageing is associated with significant decreases in rates of protein synthesis in the brain as a whole as well as in several specific brain regions. Brain regions involved in visual and auditory function were selectively affected, perhaps due to a chronic lack of sensory input. Several regions involved in motor function and two areas in the limbic system had significantly decreased rates of protein synthesis in the old rats. Notably, there was a significant age-related decrease in protein synthesis in the locus coeruleus which contains the cell bodies of origin of the major ascending noradrenergic innervation of the cortex.

Aging↗
PubMed1984

[Hypodensities accompanying various meningiomas in x-ray computed tomography].

This is a review of 80 cases of intracranial meningiomas, which were operated on in the neurosurgical Service of Lausanne. 51 tumors were associated with an area of low attenuation of variable extension on the CT-scan. In 49 of these, the low attenuation areas corresponded to oedema. In two of them a cyst was discovered at operation. One was a subarachnoid cyst and the other one was an intracerebral cyst separated from the tumor by a thin layer of cerebral cortex. A correlation was attempted between these areas of low attenuation and the clinical history, the CT-scan characteristics, the location, the macroscopic appearance at operation and the histology of the tumors. From these data, the typical features of a meningioma more likely to be associated with an area of low attenuation on the CT-scan were determined. This tumor is often located in the subfrontal area or in the middle base of the skull, and epilepsy or increased intracranial pressure are more likely to be present. The most common histological type is syncytial.

Brain Edema↗
PubMedDate not supplied

Using 80 kVp versus 120 kVp in perfusion CT measurement of regional cerebral blood flow.

Perfusion CT studies of regional cerebral blood flow (rCBF), involving sequential acquisition of cerebral CT sections during IV contrast material administration, have classically been reported to be achieved at 120 kVp. We hypothesized that using 80 kVp should result in the same image quality while significantly lowering the patient's radiation dose, and we evaluated this assumption. In five patients undergoing cerebral CT survey, one section level was imaged at 120 kVp and 80 kVp, before and after IV administration of iodinated contrast material. These four cerebral CT sections obtained in each patient were analyzed with special interest to contrast, noise, and radiation dose. Contrast enhancement at 80 kVp is significantly increased (P < .001), as well as contrast between gray matter and white matter after contrast enhancement (P < .001). Mean noise at 80 kVp is not statistically different (P = .042). Finally, performance of perfusion CT studies at 80 kVp, keeping mAs constant, lowers the radiation dose by a factor of 2.8. We, thus, conclude that 80 kVp acquisition of perfusion CT studies of rCBF will result in increased contrast enhancement and should improve rCBF analysis, with a reduced patient's irradiation.

Brain↗
PubMedDate not supplied

Development of a cavernous malformation of the brain.

We report the appearance of a cavernous malformation associated with a developmental venous anomaly in a young boy 3 years after radiation therapy for a posterior fossa medulloblastoma. The presence of a stenosis of the venous drainage of the anomaly led us to postulate that venous restrictive disease, induced by radiation therapy, resulted in increased venous pressure and caused the formation of the cavernous malformation.

Adolescent↗