Delayed Post-hypoxic Leukoencephalopathy (DPHL or Grinker myelinopathy) is a rare condition where patients recovering from an anoxic/hypoxic brain injury develops new neurological symptoms 2-4 weeks after the initial injury. Why is there a delay in symptoms?
The brain is made up of oxygen-demanding gray matter and myelin-covered white matter.
Hypoxic events initially damage the gray matter, but myelin is spared. However, new myelin secretion requires ATP-dependent enzymes which is impaired by hypoxic event. Since myelin takes about ~20 days to cycle, this coincides with the biphasic presentation of DPHL. Another theory is that oligodendrocytes (myelin-secreting cells) might have delayed apoptosis after hypoxic event, also leading to lack of new myelin formation once the old myelin degenerates.
Beeskow AB, Oberstadt M, Saur D, Hoffmann KT, Lobsien D. Delayed Post-hypoxic Leukoencephalopathy (DPHL)-An Uncommon Variant of Hypoxic Brain Damage in Adults. Front Neurol. 2018;9:708. Published 2018 Aug 27. doi:10.3389/fneur.2018.00708