Menu Healthy Lifestyle Diseases & Conditions First Aid Symptoms Tests & Procedures Videos Definitions FAQs SclerosisUpdated: 2020-02-19OverviewSclerosis is a hardening of a tissue in the body. It's caused by inflammation, scarring or disease and can limit the affected tissue's ability to function. Conditions that involve sclerosis affecting nerves, for example, include multiple sclerosis and amyotrophic lateral sclerosis (ALS). Symptoms and treatment depend on the area affected. © 1998-2022 Mayo Foundation for Medical Education and Research(MFMER). All rights reserved. Terms of Use