What is the difference between lipohyalinosis and microatheroma?

Question

Lacunar strokes (small-vessel subcortical strokes) are commonly caused by "lipohyalinosis" or "microatheroma"(1). Both mechanisms appear to be related to hypertension and diabetes, but I haven't been able to find a good definition for these terms. What is the difference between these two mechanisms?

Unfortunately this paper titled "Mechanisms in lacunar infarction" doesn't define the terms either...

Source:

1. Horowitz DR, Tuhrim S, Weinberger JM, Rudolph SH. Mechanisms in lacunar infarction. Stroke. 1992 Mar;23(3):325-7. doi: 10.1161/01.str.23.3.325. PMID: 1542890. https://pubmed.ncbi.nlm.nih.gov/1542890/

Answer 1

As the name suggests, a microatheroma is a small atheroma. An artheroma is what's commonly known as a plaque. It's a mass on the interior wall of arteries:

https://medical-dictionary.thefreedictionary.com/atheroma

atheroma [ath″er-o´mah] an abnormal mass of fatty or lipid material with a fibrous covering, existing as a discrete, raised plaque within the intima of an artery. adj., adj atherom´atous.

Lipohyalinosis, on the other hand, is a degenerative disease marked by lipids that accumulate within the walls of blood vessels:

https://medical-dictionary.thefreedictionary.com/lipohyalinosis

lipohyalinosis (lī-pō-hī′ă-lĭn-ō″sĭs) Degenerative changes in small blood vessels, marked by the accumulation of a glassy- or waxy-appearing lipid within the vessel wall. This type of vascular degeneration occurs in hypertension and atherosclerosis, and predisposes patients to small infarcts, esp. in penetrating arteries of the brain.

Both things are capable of narrowing arteries and reducing blood flow, which can cause a stroke. Plaques can also rupture, spilling plaque material into the bloodstream, which can then travel to a point where it lodges in a smaller artery and blocks it, which can also cause a stroke.