A phantom limb pain patient with a transtibial amputation experiences severe burning phantom pain refractory to gabapentin and amitriptyline. The neurophysiological mechanism underlying phantom limb pain is primarily:

• A Regenerating neuroma formation at the stump causing orthodromic impulses
• B Referred pain from the contralateral intact limb through commissural pathways
• C Cortical reorganization in the somatosensory cortex — deafferentation leads to cortical remapping with adjacent body representations invading the amputated area ✓
• D Autonomic imbalance causing sympathetically maintained pain

Explanation

The dominant mechanism of phantom limb pain is cortical reorganization (maladaptive neuroplasticity) in the primary somatosensory cortex (S1). After amputation, the cortical area previously representing the amputated limb is invaded by adjacent body part representations (typically face, hip). This mismatched sensory input is interpreted as arising from the absent limb, generating phantom sensations and pain. The degree of cortical reorganization correlates positively with pain intensity. Mirror visual feedback therapy, graded motor imagery, and prosthetic use aim to reverse this maladaptive remapping.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.