Hemorrhagic parenchymal contusion
This condition most commonly occurred in those with significant head movement or head impact. It is caused by injuries of small arterial or venous vessels, causing hemorrhage within the brain parenchyma, and give rise to hyperdense lesion on CT scan. MRI is more sensitive than CT scan in detecting such small hemorrhagic contusions, with the use of gradient echo sequence. Contusions are more commonly seen in the brain parenchyma near base of the skull such as inferior frontal lobes and temporal lobes as a result of Coup contrecoup injury. Those with parenchymal contusion would require frequent follow-up imaging because such contusions may grow large enough to become hemorrhage and exerts significant mass effect on the brain.Cerebral microhemorrhages is a smaller form of hemorrhagic parenchymal contusion and are typically found in white matter. Such microhemorrhages are difficult to be detected on CT scan, but easily detected on gradient echo and susceptibility weighted imaging on MRI scan as hypointense susceptibility blooming. Such microhemorrhages are frequently associated with diffuse axonal injury and located near the grey-white matter junction. Epidural hemorrhage
Epidural hemorrhage (extradural hemorrhage, EDH) which occur between the dura mater (the outermost meningeal layer) and the skull, is caused by trauma. It does not cross the suture lines of the skull because the superifical dural layer is attached tightly to the skull along the suture lines. Unless rarely, fracture involves the suture lines (more common in children), then epidural hematoma may cross the suture lines.
Familial exudative vitreoretinopathy (FEVR, pronounced as fever) is a genetic disorder affecting the growth and development of blood vessels in the retina of the eye. This disease can lead to visual impairment and sometimes complete blindness in one or both eyes. FEVR is characterized by incomplete vascularization of the peripheral retina. This can lead to the growth of new blood vessels which are prone to leakage and hemorrhage and can cause retinal folds, tears, and detachments. Treatment involves laser photocoagulation of the avascular portions of the retina to reduce new blood vessel growth and risk of complications including leakage of retinal blood vessels and retinal detachments. Information
Pathophysiology
FEVR is caused by genetic defects involving the regulation of blood vessel growth in developing eyes. As a result, there is poor blood vessel growth to the periphery of the retina. The lack of blood supply to the peripheral retina triggers the release of molecules that stimulate blood vessel growth, such as vascular endothelial growth factor (VEGF). However, this new blood vessel growth, also known as neovascularization, can lead to further complications such as the leakage and hemorrhage of retinal blood vessels, retinal tears, and detachments.Genetics
There have been several gene mutations associated with FEVR. These genes code for proteins involved in the WNT signaling pathway, which is involved in the development of the human eye and regulation of blood vessel growth. Depending on the genes involved, FEVR can follow an autosomal dominant, autosomal recessive, or X-linked inheritance pattern. There is varying penetrance and expressivity depending on the genes involved.