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

Brain MR imaging techniques are important ancillary tests in the diagnosis of a suspected mitochondrial encephalopathy since they provide details on brain structural and metabolic abnormalities. This is particularly true in children where non-specific neurologic symptoms are common, biochemical findings can be marginal and genetic defects may be not discovered. MR imaging modalities include conventional, or structural, imaging (MRI) and functional, or ultrastructural, imaging (spectroscopy, MRS; diffusion, DWI-ADC; perfusion, DSCI--ASL). Among them MRI and MRS are the main tools for diagnosis and work up of MD, and this review will focus mainly on them. The MRI findings of MD are very heterogeneous, as they depend on the metabolic brain defects, age of the patient, stage and severity of the disease. No correlation has been found between genetic defects and neuroimaging picture; however, some relationships between MR findings and clinical phenotypes may be identified. Different combinations of MRI signal abnormalities are often encountered but the most common findings may be summarized into three main MR patterns: (i) non-specific; (ii) specific; (iii) leukodystrophic-like. Regarding the functional MR techniques, only proton MRS plays an important role in demonstrating an oxidative metabolism impairment in the brain since it can show the accumulation of lactate, present as a doublet peak at 1.33 ppm. Assessment of lactate should be always performed on brain tissue and on the ventricular cerebral spinal fluid. As for MRI, metabolic MRS abnormalities can be of different types, and two distinct patterns can be recognized: non-specific and specific. The specific metabolic profiles, although not frequent to find, are highly pathognomonic of MD. The un-specific metabolic profiles add value to structural images in allowing to define the lesion load and to monitor the response to therapy trials.
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PMID:Brain magnetic resonance in the diagnostic evaluation of mitochondrial encephalopathies. 1751 Jul 89

Reversible focal lesions in the splenium of the corpus callosum (SCC) have recently been reported. They are circumscribed and located in the median aspect of the SCC. On MRI, they are hyperintense on T2-W and iso-hypointense on T1-W sequences, with no contrast enhancement. On DWI, SCC lesions are hyperintense with low ADC values, reflecting restricted diffusion due to cytotoxic edema. The common element is the disappearance of imaging abnormalities with time, including normalization of DWI. Clinical improvement is often reported. The most established and frequent causes of reversible focal lesions of the SCC are viral encephalitis, antiepileptic drug toxicity/withdrawal and hypoglycemic encephalopathy. Many other causes have been reported, including traumatic axonal injury. The similar clinical and imaging features suggest a common mechanism induced by different pathological events leading to the same results. Edema and diffusion restriction in focal reversible lesions of the SCC have been attributed to excitotoxic mechanisms that can result from different mechanisms; no unifying relationship has been found to explain all the pathologies associated with SCC lesions. In our opinion, the similar imaging, clinical and prognostic aspects of these lesions depend on a high vulnerability of the SCC to excitotoxic edema and are less dependent on the underlying pathology. In this review, the relevant literature concerning reversible focal lesions in the SCC is analyzed and hypotheses about their pathogenesis are proposed.
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PMID:Reversible focal splenial lesions. 1752 52

This report discusses the case of a fetus with previously normal findings of cardiotocograph that experienced an acute neurologic insult antenatally. The fetus presented with abnormalities of its heart rate tracing and its movement patterns on ultrasound. Following delivery, the infant was diagnosed with hypoxic ischemic encephalopathy by DWI in the first 24 h after birth, despite having a normal postnatal brain ultrasound.
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PMID:Acute onset antenatal fetal neurological injury suspected prenatally based on abnormalities in antenatal testing: a case report. 1991 20

Subacute MTX-induced encephalopathy is characterized by an abrupt onset of focal neurologic deficits within days after intrathecal or systemic therapy. Demyelination is one proposed mechanism. We describe the neuroimaging features of 2 patients with clinical symptoms of subacute encephalopathy after intrathecal and systemic MTX therapy. DWI showed restricted diffusion, indicating cytotoxic edema. MTI yielded no evidence of demyelination in either patient because there was no loss of MTR in areas of restricted diffusion.
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PMID:Magnetization transfer imaging provides no evidence of demyelination in methotrexate-induced encephalopathy. 2065 Oct 19

Many aspects of the pathogenesis of acute encephalitis and acute encephalopathy have been clarified in this decade, although many unknown mechanisms remain to be elucidated. According to progress of MRI and neuroimmunological analysis and the observation of clinical findings, many new syndromes were found, which enhanced our understanding of acute encephalitis and acute encephalopathy. The pathogenesis of encephalitis is divided into infection and immune mediated mechanisms. The antibodies to neuronal surface antigens(NSA) such as NMDA receptors, leucin-rich glioma inactivated 1 (LGI1) and aquaporin 4 were demonstrated in specific encephalitis, limbic encephalitis and neuromyelitis optica. Anti-NSA antibody encephalitis should be treated by immunotherapy such as corticosteroid and plasmapheresis. Acute encephalitis with refractory repetitive partial seizures (AERRPS) is a devastating postinfectious disease in children and adults, although the pathogenesis of AERRPS is poorly understood. Influenza associated encephalopathy(IAE) is characterized by it's high incidence in Japanese children between 1 year and 5 years of age, its onset in the first or the second day of illness and its high mortality (15-30%) and morbidity (25-40%). We proposed the classification of IAE with poor prognosis from the neuroradiological findings. Four types of encephalopathy seem to be differentiated from each other, acute necrotizing encephalopathy (ANE) type, hemorrhagic shock and encephalopathy syndrome (HSES) type, acute brain swelling (ABS) type, febrile convulsive status epilepticus (FCSE) type. The notable radiological features are thalamic lesions in ANE, diffuse cerebral cortical cytotoxic edema in HSES, reversible cerebral swelling in ABS which sometimes reaches lethal brain herniation, and in FCSE type, dendritic high signal in subcortical white matter by DWI ("bright tree appearance") appears simultaneously with the later onset of repetitive focal seizure. These four types are not specific to IAE but are noticed in another encephalopathies caused by HHV6, rotavirus, etc.
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PMID:[Pathogenesis of acute encephalitis and acute encephalopathy]. 2140 Aug 30

Central nervous system involvement is an uncommon though potentially a severe complication during influenza infection; the pathogenic mechanisms of the neurological syndromes described in humans are largely unknown. We describe a case of a 51-year-old man who presented with fever and behavioral changes but no focal neurological deficits. The next day, the condition rapidly evolved into a severe neurological syndrome with recurrent focal motor seizures with secondary generalization. At the brain MRI, FLAIR disclosed a slight area of increased signal in the left mesial frontal cortex extending to the frontopolar area and insula. At DWI, a mild hyperintensity was evident in the mesial-frontopolar cortex, with normal ADC values. MR perfusion was indicative of severe hypoperfusion. Fungal, bacterial and viral cultures in CSF, blood and urine were negative. The nasopharyngeal swab PCR was positive for the H1N1-influenza A virus. The patient was thus treated and by day five the neurological examination results had returned to normal. A follow-up MRI, performed two weeks later, only revealed a residual slight hyperintensity in the left medial frontal cortex. The onset of a rapidly evolving encephalopathy syndrome, its close association with a MRI brain pattern of acute vasogenic edema and favorable outcome support a diagnosis of PRES during influenza A infection. However, the topographic characteristics of the cerebral lesion seem to define a PRES with an atypical pattern.
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PMID:Unusual posterior reversible encephalopathy syndrome in a case of influenza A/H1N1 infection. 2291 Jan 47

Neonatal metabolic encephalopathy may be related to electrolyte imbalances, endocrine dysfunction, or inborn errors of metabolism. The metabolic encephalopathies are always a diagnostic challenge to the neonatologist and pediatricians. This is more so because the signs and symptoms of are nonspecific and are often similar to those with other neonatal emergencies. Clinical suspicion of neonatal encephalopathy should be considered in any infant exhibiting an abnormal level of consciousness, seizures, tone and reflex abnormalities, apnea, aspiration, and feeding difficulties. A definitive diagnosis is frequently not possible during the neonatal care unit or emergency department. But the proper initial management based on the probable diagnosis can be life-saving or reduce neurologic sequelae. In the case of inborn errors of metabolism, imaging may play a vital role either in limiting the differential diagnosis or yet times pointing towards the specific diagnosis or error of metabolism. We report DWI-ADC changes on MRI in the acute stages of neonatal nonketotic hyperglycinemia (NKH) due to sequence changes in GLDC gene.
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PMID:Characteristic MRI findings in neonatal nonketotic hyperglycinemia due to sequence changes in GLDC gene encoding the enzyme glycine decarboxylase. 2371 28

Evaluation of the multifaceted nature of frontal network syndromes is uniquely challenging and rarely tested in the acute/sub-acute stroke period. Field-dependent behavior such as imitation behavior, utilization behavior, and environmental dependency syndrome, as a component of altered environmental autonomy, may be a reliable bedside test. This research focused on the frequency of field-dependent behavior in stroke, the subtypes and relation to frontal lobe lesion location and stroke etiology. A validated frontal network score incorporating a 10-point imitation behavior scale was applied to alert patients without significant aphasia, encephalopathy, dementia, or substance abuse. Discriminative validity assessment with magnetic resonance imaging, diffusion weight imaging (MRI-DWI brain) was performed and correlational validity was established using standard neuropsychological tests. Of the stroke patients (n = 1436), those with frontal network symptoms (335/1203; 28%) were analyzed further. In the 73 patients with lesions restricted to the frontal lobes or the frontal subcortical circuits, 56 complied with the 10-point imitation behavior scale testing. Forty-five of 56 (80%) demonstrated imitation behavior (sensitivity 73% and specificity 94%). Correlational validity testing with four commonly used frontal lobe neuropsychological tests was good. The stroke etiology included 26 (59%) "other" causes, 9 (20%) intracerebral hemorrhages, 3 (7%) cardioembolic causes, 3 (7%) large vessel disease, 2 (4%) small vessel disease, and 2 (4%) unknown etiology. Field-dependent behaviour subtypes included imitation behavior (n = 45), utilization behavior (n = 9), environmental dependency syndrome (n = 4), and complex other forms of environmental dependence syndrome (n = 5). It was concluded that imitation behavior is a relatively common occurrence with lesions in the frontal lobes in the acute/sub-acute stroke period and is associated predominantly with non-mainstream (other) stroke causes and intracerebral hemorrhage.
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PMID:The panoply of field-dependent behavior in 1436 stroke patients. The mirror neuron system uncoupled and the consequences of loss of personal autonomy. 2399 79

Cerebral infarction will cause ischemic encephalopathy and lactate accumulation in the brain in acute cerebral infarction. This study investigated the optimization of pulse sequences for lactate detection and its diagnostic value in acute cerebral infarction using proton MR spectroscopy ((1)H MRS). The studies were performed on a phantom and on 17 patients with acute cerebral infarction. Examinations were performed with a GE 1.5T MRI system (Signa). The spectra were obtained using both PRESS and STEAM sequences. The spectra were processed using a GE Advantage workstation (ADW 4.3). Moreover, the optimal sequence combined with other sequences, including conventional MRI sequences and MR DWI, were used to acquire proton MRI data for 17 patients with acute cerebral infarction and 20 healthy volunteers. The maximum lactate peaks using TE=135 ms were down doublet whereas the peaks using 270 ms were up doublet. Lactate peaks were ascending in 17 patients with cerebral infarction. Optimized (1)H MRS sequences are useful for better detection of lactate in acute cerebral infarction.
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PMID:Optimization of Pulse Sequences for Lactate Detection and Its Diagnostic Value in Acute Cerebral Infarction Using (1)H MR Spectroscopy. 2402 80

Leigh syndrome (LS), or subacute necrotizing encephalomyelopathy, is the most common childhood mitochondrial encephalopathy, accounting for more than 50% of cases in this age group. Its estimated incidence is 1:40,000 - 1:77,000 liveborn infants a year. LS is a rare progressive multisystem fatal disorder inherited by autosomal recessive, X-linked and maternal transmission. Clinical onset is predominantly in the first two years of life (average: six months); 50% of patients die within a year, even though there are later- and even adult-onset forms with a more protracted evolution. LS is due to a deficit of various respiratory chain and Krebs cycle enzymes resulting in insufficient production of adenosine triphosphate (ATP), in particular cytochrome-c-oxidase (COX), pyruvate carboxylase, pyruvate dehydrogenase complex and complex I of the respiratory chain, which share an autosomal recessive and X-linked mode of transmission. Cases with maternal inheritance (MILS) are due to a mitochondrial DNA (mtDNA) point mutation. LS is clinically heterogeneous in relation to the severity of the metabolic dysfunction and is characterized by muscle involvement and especially CNS disorders, particularly psychomotor retardation, ocular symptoms, hypotonia and pyramidal signs. Death is most commonly due to respiratory failure, status epilepticus and sudden coma. The major neuropathological findings, first described by Leigh in 1951, are symmetrical foci of spongy necrosis associated with vessel proliferation and reactive gliosis in basal nuclei, brainstem and thalamus grey matter. The neuronal metabolic alteration can also affect the white matter, resulting in delayed myelination or hypomyelination. The diagnosis rests on clinical signs, elevated CSF lactate, pyruvate and alanine, and biochemical and neuroradiological data. We describe two patients with LS studied with morphological MR associated with diffusion and spectroscopy techniques to assess the diagnostic potential of standard MR imaging and establish whether the association of functional MR methods can improve its diagnostic accuracy. A case of LS with a post-mortem MR study is also described. Three patients with a diagnosis of LS based on clinical, CSF and laboratory data were studied on a GE SIGNA EXCITE 1.5 T unit using an eight-channel phased-array head coil to acquire standard sequences (SE T1; TSE DP T2; FLAIR) and echo-planar diffusion-weighted sequences (DWI; b= 1000 s/mm2) with calculation of ADC maps. The spectroscopic study used single-voxel (TE/TR ms = 144/1500) and multi-voxel techniques (TE/TR ms = 144/1000) at the level of the basal nuclei. Bilateral and symmetrical involvement of basal nuclei grey matter with T2 hyperintensity was a consistent finding in the morphological MR study. In one patient, associated white matter involvement with T2 hyperintensity in periventricular and retrotrigonal areas reflected delayed myelination or hypomyelination. The deep grey matter changes, sometimes associated with white matter lesions, suggested a diagnosis of subacute necrotizing encephalomyelopathy, in line with the literature. Acute-phase ADC values in affected areas were lower than those of normal grey and white matter and displayed signal hyperintensity on DWI. Reduced ADC values are associated with restricted water diffusivity typical of cytotoxic edema. Spectroscopy showed a high lactate peak, reflecting altered anaerobic glycolysis, and a reduced NAA peak in affected areas, which are however non-specific findings. The most informative study in these patients is standard MR associated with functional techniques, which can confirm the diagnosis obtained with morphological imaging.
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PMID:Leigh Syndrome: an MR Study of Three Cases. 2429 89


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