Subacute encephalopathy: clinical features, laboratory data, neuroimaging, and outcomes

Focal encephalopathy with recurrent episodes of epileptic status and cluster mimicking hemiconvulsion-hemiplegia-epilepsy syndrome

Hemiconvulsion-hemiplegia-epilepsy syndrome is characterized by unilateral convulsions during fever, transient hemiplegia, and subsequent partial epilepsy with atrophy in the cerebrum. A 9-year-old boy with a history of West syndrome and hypoglycemic attacks had three episodes of epileptic status and clusters mimicking HHE syndrome over a 2-year period. Magnetic resonance imaging revealed the involvement of the right and left cerebrums. Because no abnormalities were detected in an endocrine examination, screening tests for metabolic errors, or magnetic resonance spectroscopy, a diagnosis of metabolic errors was not supported. Immunohistochemistry using the patient's sera showed binding of the serum immunoglobulin with neurons in the temporal and occipital cerebral cortices, indicating the possible involvement of autoimmune mechanisms in this case. Focal encephalopathy should be considered in children showing convulsions, psychiatric disorders, and/or involuntary movements for several months in a row. In such cases, immunohistochemistry using the patient's sera may be useful for the investigation of the pathogenesis of the illness.

Serum and cerebrospinal fluid S100B, neuron-specific enolase, and total tau protein in acute encephalopathy with biphasic seizures and late reduced diffusion: a diagnostic validity

BACKGROUND

Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is characterized clinically by biphasic seizures and late magnetic resonance imaging abnormalities, such as reduced subcortical diffusion from day 3 onwards, often accompanied with some neurological sequelae. In the early stages of the disease, AESD closely resembles its far more prevalent and relatively benign counterpart, febrile seizure (FS).

METHODS

We measured and compared the serum or cerebrospinal fluid (CSF) levels of S100B, neuron-specific enolase (NSE), and total tau protein in 43 patients with FS and 18 patients with AESD, at any point during the disease. To assess early diagnostic validity, we compared these biomarkers in 43 FS and eight AESD patients, with whom the day 0-2 samples were available. We used the receiver-operator characteristic curve to evaluate the diagnostic values of these markers.

RESULTS

The levels of all biomarkers were significantly higher in AESD than FS patients. When only day 0-2 samples from AESD patients were used, the levels of all the measured biomarkers, except serum NSE, were still significantly higher in patients with AESD than in FS, suggesting that AESD could damage astrocytes, neurons, and axons, even in the early stages of the disease. According to the receiver-operator characteristic curve analyses, CSF S100B (cut-off value, 100 pg/mL) and CSF total tau protein (cut-off value, 100 pg/mL) were better predictors of AESD than other biomarkers.

CONCLUSION

The combination of CSF S100B and CSF total tau protein resulted in a positive predictive value of AESD 83.3%, which could be helpful for early diagnosis, facilitating early therapeutic interventions.

Acute encephalopathy with bilateral thalamotegmental involvement and a benign course: a case report from Brazil

This rare encephalopathy that generally affects children is preceded by a respiratory infection and fever associated with convulsions and may progress to coma. Outcome is catastrophic in most cases. This case report describes a Brazilian child of African descent with fever, cephalea and bilateral amaurosis, who evolved to coma with pyramidal signs and associated convulsions. MRI showed diffuse, symmetrical lesions in the thalamotegmental region and brainstem. Following administration of methylprednisolone, the clinical condition of the patient improved and the brain lesions regressed, leaving the child with no current neurological deficits. This was a case of acute postinfectious encephalopathy, involving various brain structures. Outcome was favourable with no sequelae following therapy. This case was atypical due to the bilateral visual involvement and extensive encephalic lesions in a child of African descent with no neurological sequelae following therapy. No other similar cases have been reported in the literature.

Mitochondrial DNA mutations affect calcium handling in differentiated neurons

Mutations in the mitochondrial genome are associated with a wide range of neurological symptoms, but many aspects of the basic neuronal pathology are not understood. One candidate mechanism, given the well-established role of mitochondria in calcium buffering, is a deficit in neuronal calcium homoeostasis. We therefore examined calcium responses in the neurons derived from various ‘cybrid’ embryonic stem cell lines carrying different mitochondrial DNA mutations. Brief (∼50 ms), focal glutamatergic stimuli induced a transient rise in intracellular calcium concentration, which was visualized by bulk loading the cells with the calcium dye, Oregon Green BAPTA-1. Calcium entered the neurons through N-methyl-d-aspartic acid and voltage-gated calcium channels, as has been described in many other neuronal classes. Intriguingly, while mitochondrial mutations did not affect the calcium transient in response to single glutamatergic stimuli, they did alter the responses to repeated stimuli, with each successive calcium transient decaying ever more slowly in mitochondrial mutant cell lines. A train of stimuli thus caused intracellular calcium in these cells to be significantly elevated for many tens of seconds. These results suggest that calcium-handling deficits are likely to contribute to the pathological phenotype seen in patients with mitochondrial DNA mutations.

Two newly proposed infectious encephalitis/encephalopathy syndromes

Two newly proposed infectious encephalitis/encephalopathy syndromes, in which magnetic resonance imaging (MRI) is essential for the diagnosis, have been reviewed. Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is reported only in East Asian infants, characterized by a febrile seizure (usually >30 min) as the initial neurological symptom on day 1, followed by secondary seizures at day 4 to 6; affected children display variable levels of neurological sequelae. MRI shows no acute abnormality during the first two days; reduced diffusion appears in the frontal or fronto-parietal subcortical white matter during days 3 to 9, then disappears between days 9 and 25. Excitotoxic injury with delayed neuronal death is hypothesized as a possible mechanism based on MR spectroscopic findings. Clinically mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is characterized by a reversible lesion with homogeneously reduced diffusion in the corpus callosum (at least involving the splenium), sometimes associated with symmetrical white matter lesions. The most common neurological symptom is delirious behavior, followed by consciousness disturbance, and seizures, all of which completely recover within a month. The reason for the transiently reduced diffusion within the lesions is unknown; possibilities that have been postulated include intramyelinic edema, interstitial edema in tightly packed fibers, and a transient inflammatory infiltrate.

Differences of clinical manifestations according to the patterns of brain lesions in acute encephalopathy with reduced diffusion in the bilateral hemispheres

BACKGROUND AND PURPOSE

The precise clinical characteristics of acute encephalopathy with bilateral reduced diffusion are not fully understood. We compared clinical, laboratory, and neuroimaging findings according to the patterns of brain lesions among children with reduced diffusion in the bilateral hemispheres.

MATERIALS AND METHODS

Nine patients were analyzed. The patterns of brain lesions were divided into diffuse lesions and central-sparing lesions. Diffuse lesions were defined as reduced diffusion in the whole cortex and/or subcortical white matter. Central-sparing lesions were defined as the lack of reduced diffusion in the areas around the bilateral Sylvian fissures. Clinical, laboratory, and neuroimaging findings were compared between groups.

RESULTS

Five patients showed diffuse lesions and 4 showed central-sparing lesions. Coma was significantly more common in patients with diffuse lesions, whereas a biphasic clinical course was more common in those with central-sparing lesions. Outcome was worse in patients with diffuse lesions. Maximal aspartate aminotransferase, alanine aminotransferase, and kinase levels were also significantly higher in patients with diffuse lesions. In 2 patients with diffuse lesions, diffusion-weighted images during the acute phase revealed reduced diffusion in the bilateral frontal and occipital areas, followed by diffuse lesions. No patient with central-sparing lesions showed MR imaging abnormalities during the acute phase.

CONCLUSIONS

Clinical manifestations in patients with diffuse lesions were severe, whereas those in patients with central-sparing lesions were relatively mild.