Undergrad Rounds: Phantom Limb Syndrome

Phantom Limb Syndrome

The condition where individuals feel sensations (including pain) in a limb that is no longer there.

Two types:

1. Phantom sensations → mechanoreceptors → DCML pathway

2. Phantom limb pain → nociceptors → spinothalamic tract

Neuroma

The benign growth of nerve tissue at the severed nerve end causes spontaneous firing. The spontaneous firing travels dorsally into the dorsal root ganglion, where they then fire off ventrally spontaneously and cause phantom pain.

Treatment

No cure for phantom limb sensation, but there are effective treatments. Mirror therapy creates the illusion to the brain that the limb is still attached, allowing the brain to perceive movement in the missing limb. 

Stump revision surgery and injections can also provide relief from phantom limb pain. Medications such as anticonvulsants and tricyclic antidepressants can also relieve pain.

Transcutaneous electrical nerve stimulation is also a form of treatment that uses the gate theory of pain. 

Central Nervous System Reorganization

Studies have shown that neighboring areas invade the amputated limb area, and that greater invasion equates to greater pain. They have also found that stump areas expand into the amputated limp, and stimulation of this area generates phantom sensations.