Thalamic Damage in Periventricular Leukomalacia (PVL)

Abstract

The thalamus is an integral structure in the processing and relaying of cognitive, emotional, and sensory information, and thalamic damage in the premature period could contribute to long‐term neurological disabilities in survivors. A recent study by us identified that premature infants with PVL had thalamic injury at autopsy, characterized by neuronal loss (38%) and/or gliosis (56%) (Pierson et al. Acta Neuropathol 2007). Here we sought to establish the spectrum and regional pattern of thalamic injury, as well as the role of axonal injury. We studied 21 thalami in PVL cases ranging from 24 to 41 gestational weeks (mean, 33.3 ± 1.0 weeks) and 25 to 56 postconceptional weeks (mean, 37.8 ± 1.5 weeks) from the pathology archives of our hospital. There was a spectrum of injury in 71% of the thalami, from mild (10%) to severe (24%), with profound neuronal loss, gliosis, and mineralization. Parenchymal axonal spheroids were present in 19% of thalami with acute/subacute injury; one case had microinfarction. The mediodorsal nucleus (limbic relay) was involved in 66% of the cases. These data suggest that the incidence of thalamic injury is even more prevalent in PVL then originally reported by us, as determined by more extensive analysis of individual cases, and that the underlying substrate of emotional as well as cognitive disorders in survivors may reflect, at least in part, damage to relevant thalamic subnuclei.