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Query: UMLS:C0085584 (encephalopathy)
 18,178 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Evidence indicates that the accumulation of glutamine in the brain plays an important role in the pathogenesis and severity of the encephalopathy of acute liver failure (ALF). This study uses in vivo proton magnetic resonance spectroscopy (1H MRS) to assess brain glutamine (GLN) in five cases of acute liver failure. The findings are consistent with prior investigations and suggest that the alpha 1H of the GLN molecule can be used for noninvasive spectroscopic quantitation of brain GLN in patients with ALF.
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PMID:Proton spectroscopy of brain glutamine in acute liver failure. 862 Nov 71

Familial hemiplegic migraine (FHM) is a rare autosomal dominant disorder of unknown pathogenesis characterized by migraine and transitory hemiplegic attacks. We describe a kindred fulfilling the diagnostic criteria for FHM in which: (1) brain phosphorus magnetic resonance spectroscopy (31P-MRS) showed a reduced phosphocreatine content accompanied by high [ADP], high percentage of V/Vmax of ATP biosynthesis and decreased phosphorylation potential; (2) muscle 31P-MRS showed a reduced rate of phosphocreatine recovery after exercise; (3) blood lactate was increased after effort; (4) muscle biopsy showed, in one patient, rare ragged red fibers succinate-dehydrogenase positive and cytochrome c oxidase negative; (5) genetic analysis of muscle mitochondrial DNA did not show any of the two point mutations in the tRNA(Leu(UUR)) associated with the MELAS syndrome (Mitochondrial myopathy, Encephalopathy with Lactic Acidosis and Stroke-like episodes). The defective energy metabolism of brain and muscle found in this pedigree suggests a multisystemic disorder of mitochondrial function in this FHM pedigree.
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PMID:Abnormal brain and muscle energy metabolism shown by 31P-MRS in familial hemiplegic migraine. 760 38

We report here a glycogen storage myopathy type V associated with multifocal encephalopathy. The patient, a 43-year-old male with increased serum CK, a heavy drinker and smoker, had been affected by generalized epilepsy since age 24, after a cranial injury. He had had a right hemiparesis 2 years before coming to our observation and a transient left hemiparesis the following year. CT and MRI of the brain showed multiple hemispheric lesions consistent with an ischemic process, as suggested by single photon emission tomography of the brain. Muscle biopsy showed a vacuolar myopathy, and myophosphorylase activity was 13% of the normal mean. Phosphorus magnetic resonance spectroscopy (31P-MRS) performed on resting calf muscles showed increased PCr to ATP and decreased PCr to P(i) ratios. During both aerobic and ischemic exercise 31P-MRS failed to show any cytosolic acidification and phosphomonoesters (PME) accumulation, two MRS findings in agreement with McArdle's syndrome diagnosis. Mitochondrial respiration was also affected as shown by a low PCr to P(i) ratio at rest and by a low rate of PCr re-synthesis during recovery from aerobic exercise. This latter finding in McArdle's disease can be explained by decreased mitochondrial substrate availability, which in turn can contribute to the phenotypic manifestations of the disease.
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PMID:Myophosphorylase deficiency affects muscle mitochondrial respiration as shown by 31P-MR spectroscopy in a case with associated multifocal encephalopathy. 772 38

Neurological manifestations of HIV disease occur in most adults and children with AIDS. Many of those affected will inevitably suffer clinical neurological deficits involving mental function, movement, and sensation. Surprisingly, there are not as yet adequate monitoring systems to predict the onset and/or progression of HIV infection of the CNS. Neurological, neuropsychological, CSF, and magnetic resonance imaging (MRI) analyses cannot accurately detect mental deterioration during advancing HIV disease. Reports suggest that in vivo proton MR spectroscopy (1H MRS) of the brain could be a predictor of virus-induced neurological deterioration. H MRS can measure N-acetylaspartate (NAA), a metabolite present only in neurons. Decreased NAA reflects neuronal loss seen during HIV infection of brain. To uncover possible associations between NAA levels and HIV-induced neurological disease we performed serial 1H MRS brain tests in HIV-infected patients with or at risk for encephalopathy. Serial testing, for 1 year, of 10 patients showed that brain NAA levels decreased in all HIV-infected subjects. The most severe NAA reductions were associated with progressive neurological impairment. These findings suggest that NAA can be used as a noninvasive measure of neuronal loss in patients with HIV disease. Most important, the results suggest that 1H MRS could be used to monitor therapeutics directed against HIV infection within the CNS.
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PMID:Prospective utility of cerebral proton magnetic resonance spectroscopy in monitoring HIV infection and its associated neurological impairment. 781 49

Neurological and neuroelectrophysio-biochemical profiles were evaluated in newborn lambs exposed to severe temporary asphyxia. Isoelectric EEG, marked disturbances of phosphorus magnetic resonance spectrum (31P-MRS), and significant brain intracellular acidosis (pHi) were noted during asphyxia. Following resuscitation, the presence of early postasphyxic blood-brain-barrier (BBB) opening was associated with a marked transient increase in intracranial pressure (ICP), a 50% neonatal mortality and a 67% incidence of severe asphyxic encephalopathy. In contrast, those lambs exposed to the same magnitude of asphyxia, but without early BBB opening experienced neither death nor severe neurological deficits. Further, these lambs showed a rapid progressive normalization of the 31P-MRS and pHi, despite, the lack of EEG recovery in the first hour following resuscitation. Thus, the present study depicts that the early postasphyxic BBB disruption following temporary neonatal asphyxia is associated with poor prognosis.
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PMID:Neuro-pathophysio-biochemical profiles of neonatal asphyxia. 797 47

Nuclear magnetic resonance imaging and spectroscopy have added significant new information about the newborn brain during and following asphyxia. NMR imaging has permitted sequential in vivo analysis of CNS maturation in the perinatal period that is superior in anatomic resolution, and especially in the characterization of myelination, to either cranial ultrasound or radiographic computed tomography. As a result, the accurate detection and recognition of the brain lesions associated with hypoxic-ischemic encephalopathy is now possible, including PVL, cerebral infarction, intraparenchymal and intraventricular hemorrhage, and delayed myelination. This has improved our understanding of the associated potential risk for abnormal neuro-developmental outcome with specific lesions. NMR spectroscopy has provided a metabolic window into the biochemical events during and following asphyxia. 31P MRS captures the phosphorous metabolites as levels rise and fall and shift in relation to each other to maintain cellular energy homeostasis in the face of oxygen depletion. Meanwhile, proton NMR spectroscopy promises to sustain the metabolic purview beyond the immediate cellular response to asphyxia to the chronic adaptation phase. Appropriately applied, this noninvasive technology may yet enable us to identify brain injury that is reversible in sufficient time to intervene and to diagnose accurately what is irreversible for timely prognostication. Furthermore, the integration of clinical imaging and spectroscopy capabilities is both feasible and desirable; information provided by each being mutually complementary. Imaging could improve spectroscopy interpretation by identifying the observed tissue, whereas MRS should clarify diagnosis of anatomic lesions detected by MRI. Advances in spatial resolution and speed of data acquisition may soon make integrated MRI/MRS a clinical reality.
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PMID:Nuclear magnetic resonance imaging and spectroscopy following asphyxia. 835 55

4.1 CURRENT STATUS. While an extensive clinical literature of MRS of muscle, brain, heart and liver has been achieved, the MRS technique is not considered essential for routine diagnosis because it is inherently insensitive and metabolic changes tend to be small. However, MRS techniques have proven to be of considerable value for prognosis in some circumstances, notably for predicting outcome following hypoxic-ischaemic injury in the newborn and also in predicting graft viability following organ transplantation. The chemical specificity of MRS has been illustrated, and exploiting the non-invasive nature of the technique, metabolic fingerprinting of pathophysiological processes throughout the natural history of a wide variety of diseases is now being accomplished. Particularly exciting are the applications of 13C MRS for measuring hepatic and muscle glycogen levels, for example in diabetics, and the use of hepatic 31P MRS for assessing liver function in cirrhosis. Other areas of excitement are the applications of 1H MRS in assessing neuronal function in epilepsy and stroke, and for measuring the evolution of lactate in stroke and hypoxic-ischaemic encephalopathy. Emphasis on technique development continues, and applications still tend to be technology-led. The availability of routine clinical MRI systems with spectroscopy capabilities has given MRS studies wider applicability. The recent improvements in spatial resolution have been impressive and the technique is slowly becoming more quantitative. 4.2. FUTURE PERSPECTIVES. Given the flexibility of clinical magnetic resonance techniques, particularly magnetic resonance imaging, it is likely that MRI will be the diagnostic tool of choice in a wider range of diseases, such as multiple sclerosis, stroke, neurodegenerative conditions, sports injuries and in staging malignancies. Since proton magnetic resonance spectroscopy packages have become a routine addition to many MRI systems, it is feasible to select the MRI sequences of most value in highlighting anatomical and pathological abnormalities and to incorporate specifically selected MRS sequences to emphasize biochemical differences. Improvements in technical methodologies are central to further developments. For example, use of internal coils, such as implantable or endoscopic coils, will enable small regions of tissue to be studied in considerable detail, which may otherwise be inaccessible to measurement. Chemical MRS studies have benefited from the use of higher magnetic fields, and the same may be expected for clinical MRS studies. Whole-body magnets up to 4 T have been used in a few centres, and certainly 3 T systems are becoming more widely available with the recent tremendous interest in functional imaging. Certainly, better control of artefacts can be expected; for example, improved definition of spectral changes due to voluntary or involuntary movements. Wider use of proton decoupling methods will improve the specificity of the spectra, by allowing definitive assignments of overlapping resonances, as well as the sensitivity. Comparing PET and MRS studies, it is becoming increasingly obvious that both will be required in parallel to explore parameters of brain metabolism and function. The ability to measure 13C MR signals in the brain has been demonstrated, which allows measurements of glutamate and glucose turnover. MRS measurements have the advantage of not requiring a radioactive isotope, as well as being insensitive to activity-related changes in regional cerebral blood flow. Also the study of cerebral glucose metabolism by MRS is very promising, allowing a resolution and sensitivity comparable to PET. A combination of MRS and PET studies will allow the pathogenesis of neuropsychiatric disorders to be better understood. (ABSTRACT TRUNCATED)
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PMID:Development and applications of in vivo clinical magnetic resonance spectroscopy. 902 41

Proton MRS has proved useful in the early diagnosis of HIV-related encephalopathy. The modifications of brain metabolism in HIV-related encephalopathy can be classified according to different metabolic patterns (Vion-Dury J et al. CR Acad Sci 1994;317:833-840). The present study describes the relative occurrence of these patterns and evaluates their evolution under zidovudine treatment. We have examined 112 HIV patients--35 neuroasymptomatic patients and 77 patients with ADC (AIDS dementia complex)--with localized proton MRS, using the PRESS 135-msec sequence. We have found the same metabolic modifications in N-acetylaspartate and choline-containing compounds as described in the literature. In addition, 14% of HIV patients with normal MRI displayed abnormal MRS, whatever their neurological status. The MRS-added diagnostic value in neuroasymptomatic patients reaches 30 %. The occurrence of undifferentiated (modification of NAA/Cho ratio only) and Cho (mainly an increase in choline signal) patterns is not significantly different in neuroasymptomatic and ADC patients. The NAA pattern (mainly a significant loss of NAA) is more frequent in ADC patients. Only ADC patients display the double pattern (with a significant increase in choline signal and a significant loss of NAA). Quantitated cerebral atrophy (bifrontal ratio) is related to the occurrence of NAA loss (in NAA and double patterns). An MRS follow-up study of 11 HIV patients showed that the clinical outcome was favorable after a 1000-mg/day zidovudine treatment in patients displaying an NAA pattern whereas this treatment had no effect on the patients displaying the Cho pattern. Consequently, MRS appears to be of great interest in predicting responsiveness to antiretroviral drugs and detecting early any resistance to treatment.
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PMID:Brain proton magnetic resonance spectroscopy in HIV-related encephalopathy: identification of evolving metabolic patterns in relation to dementia and therapy. 926 93

We examined brain energy metabolism by phosphorus-31 magnetic resonance spectroscopy (31P-MRS) in the occipital cortex in a mother and a daughter with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) during photic stimulation. The peak area ratio of phosphocreatine markedly decreased during photic stimulation, and subsequently increased after the stimulation. This method, photic stimulation-31P-MRS, may be useful in assessing brain energy metabolism in neurological diseases.
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PMID:Photic stimulation-induced alteration of brain energy metabolism measured by 31P-MR spectroscopy in patients with MELAS. 956 64

In this prospective study proton magnetic resonance spectroscopy (1H MRS) was used to test the hypothesis that lactate can be detected later than 1 mo after birth in the brains of infants who display severe neurodevelopmental impairment 1 y after transient perinatal hypoxia-ischemia. Data were obtained from three groups of infants: 1) eight infants suffering birth asphyxia followed by perinatal encephalopathy and abnormal neurodevelopmental outcome at 1 y of age (defined as major neurologic impairment, Griffiths quotient <85%, and low optimality score); 2) 10 infants with signs of perinatal hypoxia-ischemia but normal neurodevelopmental outcome at 1 y; and 3) six control infants with uneventful perinatal courses and normal neurodevelopment at 1 y. Between one and four examinations (median 1) were performed at median (range) 11 (4-68) wk after birth, and the cerebral concentration ratio of lactate to creatine plus phosphocreatine (Cr) calculated from each spectrum. Lactate was detected later than the 1st mo after birth in seven of eight infants with abnormal neurodevelopmental outcome [maximum detected lactate/Cr was median (range) 0.44 (0.24-0.67)]. No lactate was detected later than the 1st mo after birth in infants with normal neurodevelopmental outcome, nor in five of six control subjects, although a small amount of lactate was detected in one control infant (lactate/Cr=0.04). These results suggest that the pathologic postasphyxial process, indicated by persistent cerebral lactate, may not be confined to the period immediately after injury.
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PMID:Persistent increases in cerebral lactate concentration after birth asphyxia. 972 5


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