** Shares of Australia's PainChek Ltd PCK.AX rise as much as 31.3% to A$0.105, their highest level since mid-August 2020

** Stock posts its biggest intraday pct gain since early-October 2023

** Medical technology firm says U.S. FDA granted De Novo classification for its PainChek Adult App

** PainChek Adult App is a smartphone-based pain assessment tool designed for individuals who cannot self-report pain, such as those with moderate to severe dementia

** De Novo classification refers to regulatory pathway used by the FDA to evaluate and approve novel medical devices that do not have an existing legally marketed equivalent

** Nearly 18.5 million shares change hands, 4.9x the 30-day average volume

** Stock has risen 186.2% this year, including session gains

(Reporting by Roshan Thomas in Bengaluru)

((Roshan.Thomas@thomsonreuters.com))