Endocrine Abstracts

Background: Children with hyperinsulinaemic hypoglycaemia (HH) are at a high risk of brain injury, while children with ketotic hypoglycaemia (KH) are believed to be neurologically normal. Hippocampus is known to be susceptible to hypoglycaemia, and is one of the key structures in the memory system. Our objective was to ascertain if children with HH sustain greater hippocampal injury and memory deficits in comparison to children with KH.

Methods: Twenty one neurologically normal children between 5 and 16 years of age with HH and 14 children with KH were recruited from the endocrine and metabolic outpatient clinic database from 2009 to 2012. Cognitive assessment was performed using Wechsler Intelligence Scale for Children Fourth edition and Children Memory Scale. Conventional (T1, T2 weighted) MRI for visual inspection of hippocampus and fast low angle shot (FLASH) three-dimensional MRI for manual hippocampal volume measurement were acquired.

Results: HH group scored significantly lower in general memory (KH 110 vs HH 93.1, P 0.002), especially visual (KH 106.3 vs HH 94.8, P 0.022), verbal immediate (KH 110.5 vs HH 94.9, P 0.006) and verbal delayed memory (KH 108.7 vs HH 97.2, P 0.055) and also in Full scale IQ (KH 100.5 vs HH 89.3, P=0.026). On conventional MRI small hippocampi were seen in 28.5% with HH and 7% with KH, however no significant differences in hippocampal volumes were seen in the right (P 0.959) or left (P=0.877) hippocampus between the KH and HH groups. Hippocampal volumes did not correlate to memory indices in HH group. Three children in the HH group had >20–25% reduction in bilateral hippocampal volumes, however only one child had impaired memory.

Conclusions: Children with HH manifest significant impairment of memory that do not correlate with hippocampal volumes. Further studies are required to determine the neural substrate underlying these memory impairments.