The most common early symptoms of these intracanalicular (IAC) VSs are gradual hearing loss and a feeling of fullness in the affected ear, some imbalance or dizziness, and tinnitus (ringing or other noise in the ear). Gradual single-sided hearing loss in the high frequencies is the first most obvious symptom for the great majority of patients. Headache as a presenting symptom of VS specifically is rare; facial symptoms (facial numbness, weakness) usually occur only as the tumor grows out of the canal and/or after therapeutic treatment. Delayed diagnosis and misdiagnosis are not unusual. Initial hearing loss is usually subtle and may be attributed mistakenly to aging, earwax buildup, or perhaps exposure to some loud environmental noise. A sudden hearing loss, which is uncommon, might be misdiagnosed as Ménières disease, an abnormality of the inner ear that also has tinnitus as a symptom. The brains vestibular system usually compensates for early balance problems. There have been cases of tumors that were actually asymptomatic until very large and at a critical stage. Tumor growth rates are highly variable: some small VSs (perhaps 50%) do not grow at all; some few grow for a time and then shrink; some appear dormant but suddenly grow rapidly. In general, although studies differ, VSs that grow are slow-growing at an average rate of 1.2 to 1.9 mm per year. IAC tumors that grow beyond 1.5 cm in diameter expand into the relatively empty space of the cerebellopontine angle, taking on the characteristic ice-cream-cone appearance seen on MRIs.
The process is worsened if it is insufficient high-density lipoprotein (HDL), the lipoprotein particle that removes cholesterol from tissues and carries it back to the liver.The foam cells and platelets encourage the migration and proliferation of smooth muscle cells, which in turn ingest lipids, become replaced by collagen, and transform into foam cells themselves. A protective fibrous cap normally forms between the fatty deposits and the artery lining (the intima).These capped fatty deposits (now called atheromas) produce enzymes that cause the artery to enlarge over time. As long as the artery enlarges sufficiently to compensate for the extra thickness of the atheroma, then no narrowing ("stenosis") of the opening ("lumen") occurs. The artery becomes expanded with an egg-shaped cross-section, still with a circular opening. If the enlargement is beyond proportion to the atheroma thickness, then an aneurysm is created. Visible features
Although arteries are not typically studied microscopically, two plaque types can be distinguished:
The fibro-lipid (fibro-fatty) plaque is characterized by an accumulation of lipid-laden cells underneath the intima of the arteries, typically without narrowing the lumen due to compensatory expansion of the bounding muscular layer of the artery wall. Beneath the endothelium, there is a "fibrous cap" covering the atheromatous "core" of the plaque. The core consists of lipid-laden cells (macrophages and smooth muscle cells) with elevated tissue cholesterol and cholesterol ester content, fibrin, proteoglycans, collagen, elastin, and cellular debris.