Lipohyalinosis

Lipohyalinosis is a cerebral small vessel disease affecting the small arteries, arterioles or capillaries in the brain. Originally defined by C. Miller Fisher as 'segmental arteriolar wall disorganisation', it is characterized by vessel wall thickening and a resultant reduction in luminal diameter. Fisher considered this small vessel disease to be the result of hypertension, induced in the acute stage by fibrinoid necrosis that would lead to occlusion and hence lacunar stroke. However, recent evidence suggests that endothelial dysfunction as a result of inflammation is a more likely cause for it. This may occur subsequent to blood–brain barrier failure, and lead to extravasation of serum components into the brain that are potentially toxic. Lacunar infarction could thus occur in this way, and the narrowing – the hallmark feature of lipohyalinosis – may merely be a feature of the swelling occurring around it that squeezes on the structure.

==Misuse of the term== C. Miller Fisher had decided to make lipohyalinosis a substitute term for fibrinoid necrosis. Fisher had done this because "of what he perceived to be the general agreement that the affected arteriolar segments also contained lipid". This has caused some issues with the usage of the term lipohyalinosis. "Because of its use by some earlier authors, Fisher included "hyalinosis" in the list of synonyms that also included the term "fibrinoid"". This means that people often associate hyalinosis and hyaline with lipohyalinosis and consider them the same thing. The misuse of the term lipohyalinosis also has meant that many cerebral vessel pathology have been incorrectly described as lipohyalinosis. This misuse of lipohyalinosis may cause issues for accurate diagnosis and therefore treatment of specific conditions if used incorrectly on a patient.