Cellular metamorphosis

From Memory Alpha, the free Star Trek reference.

Cellular metamorphosis is a discipline practiced by the natives of Antos IV.

During the mid-23rd century, cellular metamorphosis allowed Starfleet Captain Garth of Izar to recover from serious injuries he had sustained in the line of duty. This technique enabled Garth to repair his physical injuries, but unfortunately caused mental disturbances leading to insanity. (TOS: "Whom Gods Destroy")