The glucose-transporter protein and glucopenic brain injury

The oral glucose tolerance test is frequently abnormal in patients with uncontrolled epilepsy

PURPOSE

The clinical efficacy of the ketogenic diet as therapy for patients with difficult-to-treat epilepsy prompted us to investigate the glucose metabolism of these patients under an oral overload of glucose, that is, in the oral glucose tolerance test (OGTT).

METHODS

Thirty patients (12 males, 18 females; age range: 17-59, mean: 35.1) with difficult-to-treat epilepsy, 23 patients with controlled epilepsy (11 males, 12 females; age range: 14-66, mean: 36.9), and 39 control subjects (18 males, 21 females; age range: 16-58, mean: 33.3) were evaluated with the OGTT. For patients with epilepsy, we also measured C-peptide and glycosylated hemoglobin in the fasting state. Glucose levels lower than 70 mg/dL at any point of the curve were considered to be abnormal.

RESULTS

All subjects in the control group and the group with controlled epilepsy had a normal OGTT. In contrast, all 30 patients with difficult-to-treat epilepsy had at least one point on the OGTT curve below the normal range (P<0.001), most often 180 and 240 minutes after the oral glucose load (P<0.001). C-peptide levels were significantly lower in the group with difficult-to-treat epilepsy as compared with the group with controlled epilepsy. Fasting glycohemoglobin and insulin levels did not differ between the two patient groups.

CONCLUSIONS

We suggest that undiagnosed metabolic disturbances in patients with difficult-to-treat epilepsy may somehow contribute to their refractoriness to conventional pharmacological therapy. We propose the hypothesis that calorie-restricted diets aimed at correcting OGTT curves may prove beneficial in treating patients with difficult-to-treat epilepsy. Our hypothesis generates a clear endpoint for the diet, and its demonstration would provide new standards for diet-based antiepileptic regimens. Accordingly, our results may help in understanding the positive consequences of ketogenic or calorie-restricted diets in persons with seizures.

Neonatal seizures

Neonatal seizures typically indicate significant underlying disease.They are poorly classified, under-recognized, and often difficult to treat. Recognition of etiology is often helpful in prognosis and treatment; the most common is hypoxic-ischemic encephalopathy. Patients generally have a poor prognosis, with most developing a severe encephalopathy and epilepsy. Studies suggest that neonatal seizures and their etiology have a significant impact on the developing brain; it is critical to recognize seizures early and initiate immediate antiepileptic therapy. Continuous computerized simultaneous video electroencephalograph monitoring is imperative;at-risk infants will frequently have electrographic seizures without clinical manifestations. Although there are antiepileptic therapies for neonatal seizures, they are ineffective in over 35% of cases. The goal of research should be the development of more effective therapies for neonatal seizures, regardless of etiology.

Glucose and the newborn baby: sweet justice?

Neonatal hypoglycaemia remains a controversial issue. Uncertainty surrounds what constitutes the optimal safe blood glucose for newborn babies. There are good reasons and evidence for maintaining blood glucose greater than 2.5 mmol/L in newborn babies. Since 1986 neonatal paediatricians have changed in their definition of neonatal hypoglycaemia. Ideally, screening of blood glucose in neonatal intensive care units should be done with an on-site glucose analyzer.

The role of fever on cerebrospinal fluid glucose concentration of children with and without convulsions

In febrile convulsions glucose concentrations are known to increase both in the blood and cerebrospinal fluid (CSF). The reason behind this increase is, however, incompletely understood. We have studied the effects of convulsion and fever on the CSF and blood glucose concentrations in four different groups of children: febrile and non-febrile children, with and without convulsions. The concentration of glucose in the CSF was significantly higher in febrile children with (4.4 +/- 0.1 mmol/l, mean +/- SEM n = 35, p < 0.01. ANOVA, Duncan's test) and without convulsions (3.9 +/- 0.2 mmol/l, n = 22, p < 0.05) than in non-febrile, non-convulsive children (3.3 +/- 0.1 mmol/l, n = 21). In non-febrile convulsive children, the CSF glucose concentration was 3.7 +/- 0.2 mmol/l (n = 10). Both fever and seizures increased the CSF glucose levels (p < 0.0001) and p = 0.028, respectively, analysis of covariance). There was a linear correlation between the body temperature and concentration of glucose in the CSF (r = 0.454, p < 0.0001, n = 88, Pearson's correlation analysis). The changes in blood glucose concentrations between the groups paralleled those found in the CSF. Our results show that hyperglycaemia and an increase in the CSF glucose concentration in febrile convulsions is not explained just by a stress reaction, evoked by the seizure, as has been hypothesized earlier, but by the influence of increased body temperature as well.