Developmental amnesia associated with early hypoxic-ischaemic injury

We recently reported on three young patients with severe impairments:of epi sodic memory resulting from brain injury sustained early in life. These fin dings have led us to hypothesize that such impairments might be a previousl y unrecognized consequence of perinatal hypoxic-ischaemic injury. Neuropsyc hological and quantitative magnetic resonance investigations were carried o ut on five young patients, all of whom had suffered hypoxic-ischaemic episo des at or shortly after birth. All five patients showed severe impairments of episodic memory (memory for events), with relative preservation of seman tic memory (memory for facts). However, none had any of the major neurologi cal deficits that are typically associated with hypoxic-ischaemic injury, a nd all attended mainstream schools. Quantitative magnetic resonance investi gations revealed severe bilateral hippocampal atrophy in all cases. As a gr oup, the patients also showed bilateral reductions in grey matter in the re gions of the putamen and the ventral part of the thalamus, On the basis of their clinical histories and the pattern of magnetic resonance findings, we attribute the patients' pathology and associated memory:impairments primar ily to hypoxic-ischaemic episodes sustained very early in life. We suggest that the degree of hypoxia-ischaemia was sufficient to produce selective da mage to particularly vulnerable regions of the brain, notably the hippocamp i, but was not sufficient to result in the more severe neurological and cog nitive deficits that can follow hypoxic-ischaemic injury. The impairments i n episodic memory may be difficult to recognize, particularly in early chil dhood, but this developmental amnesia can have debilitating consequences, b oth at home and at school, and may preclude independent life in adulthood.