Astrocytosis ('astrogliosis') is an abnormal increase in the number of
astrocytes due to the destruction of nearby
neurons, typically because of
hypoglycemia or oxygen deprivation (
hypoxia).
It usually takes place in prion infections. It is especially prevalent in
fatal familial insomnia, a prion infection affecting the thalamus and circadian rhythms. The disease causes insomnia to the point that death results.
This manifests as astrocytic
edema,
hypertrophy, proliferation, and increased motility.