Cal. Lab. Code § 5803
The appeals board has continuing jurisdiction over all its orders, decisions, and awards made and entered under the provisions of this division, and the decisions and orders of the rehabilitation unit established under Section 139.5. At any time, upon notice and after an opportunity to be heard is given to the parties in interest, the appeals board may rescind, alter, or amend any order, decision, or award, good cause appearing therefor.
This power includes the right to review, grant or regrant, diminish, increase, or terminate, within the limits prescribed by this division, any compensation awarded, upon the grounds that the disability of the person in whose favor the award was made has either recurred, increased, diminished, or terminated.
Ca. Lab. Code § 5803