Fal-tor-voh is a treatment for a Vulcan degenerative neurological disease, involving a mind meld.

The disease causes the neuropeptide levels in the brain to decrease, and affects the logic capabilities. The treatment could only be performed by a Vulcan who was compatible with the patient, which usually meant a blood relative.

In 2378, Tuvok required fal-tor-voh as he began showing symptoms of the disease. However, neither of the Vulcans on USS Voyager were compatible, and he required a relative in the Alpha Quadrant.

In the original timeline, where Voyager spent twenty-three years in the Delta Quadrant, he returned home far too late for the treatment, and by 2404, Tuvok's mind had suffered irreparable damage, leading him to be permanently quartered in a mental hospital. (VOY: "Endgame")