An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Beal MF, Martin JB.Beal MF, et al. Among authors: martin jb.Ann Neurol. 1986 Nov;20(5):547-65. doi: 10.1002/ana.410200502.Ann Neurol. 1986.PMID: 2947536Review.