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Regional cerebral blood flow during hypoglycaemia in children with IDDM
I T Jarjour1, C M Ryan, D J Becker
1Department of Medicine (Neurology), Allegheny General Hospital, Medical College of Pennsylvania, Pittsburgh, USA.
Insights
Mild hypoglycaemia (low blood sugar) increases cerebral blood flow, particularly in grey matter and the right hemisphere. This asymmetrical blood flow change may explain neurological deficits in children with diabetes.
Area of Science:
- Neurology
- Pediatrics
- Endocrinology
Background:
- Hypoglycaemia can cause temporary cognitive and neurological issues, often affecting one side of the body.
- Understanding the brain's response to low blood sugar is crucial for managing diabetes in children.
Purpose of the Study:
- To investigate the effects of mild hypoglycaemia on cerebral blood flow (CBF) and cerebrovascular resistance (CVR) in children with insulin-dependent diabetes mellitus.
- To determine if hypoglycaemia causes asymmetrical changes in brain blood flow.
Main Methods:
- Eight children with type 1 diabetes underwent assessment of regional CBF and CVR using the intravenous xenon-133 clearance method.
- Measurements were taken during both normal blood glucose levels (euglycaemia) and mild hypoglycaemia.
Main Results:
- Global mean cerebral grey matter blood flow showed a statistically significant increase during mild hypoglycaemia.
- Cerebral grey matter blood flow was significantly higher in the right hemisphere compared to the left during hypoglycaemia.
- A trend towards increased global mean cerebral blood flow and decreased cerebrovascular resistance was observed.
Conclusions:
- Mild hypoglycaemia is associated with increased cerebral blood flow, especially in grey matter and the right hemisphere.
- The observed asymmetrical blood flow changes may underlie the unilateral neurological deficits seen in severe hypoglycaemia.
- These findings highlight the brain's complex response to low blood sugar in diabetic children.
Abstract:
Hypoglycaemia may cause transient cognitive impairment and neurological deficits that are frequently unilateral. The effect of mild hypoglycaemia (serum glucose level 3.4 +/- 0.1 mmol/l; mean +/- SEM) on regional cerebral blood flow and cerebrovascular resistance was studied in eight right-handed children with insulin-dependent diabetes mellitus (age 14.9 +/- 0.7 years; diabetes duration 7.4 +/- 1.1 years; six males) using the intravenous xenon-133 clearance method. Global mean cerebral grey and white matter blood flow, adjusted to mean pCO2 of cohort, showed a trend towards an increase from 54.7 +/- 3.5 ml.100 g-1.min-1 at baseline euglycaemia to 58.0 +/- 4.1 ml.100 g-1.min-1 during hypoglycaemia (p = 0.075). Statistically significant changes were seen in global mean cerebral grey matter blood flow, as indexed by initial slope, which increased from 88.0 +/- 6.5 min-1 before hypoglycaemia to 96.3 +/- 7.2 min-1 during hypoglycaemia (p < 0.05). Cerebral grey matter blood flow was significantly higher in the right hemisphere compared to the left during hypoglycaemia (p < 0.01) but not at baseline euglycaemia. Measurements of global cerebrovascular resistance showed a borderline decrease from 1.64 +/- 0.11 to 1.54 +/- 0.11 mm Hg.ml-1.100 g-1.min-1 (p < 0.09). In conclusion, mild hypoglycaemia is associated with increases in cerebral blood flow which are greater in grey matter flow indices and in the right hemisphere. We speculate that asymmetrical cerebral blood flow changes may explain the frequent laterality of neurological deficits during severe hypoglycaemia.