Botulinum Toxin for Central Neuropathic Pain

Botulinum toxin (BTX) is commonly used for muscle spasticity by affecting motor neurons. Recent research explores BTX's impact on sensory nerves, particularly in treating peripheral and central neuropathic pain. Central neuropathic pain includes conditions like spinal cord injury-related pain, post-stroke shoulder pain, multiple sclerosis-related pain, and complex regional pain syndrome. BTX's functional effect occurs at the neuromuscular junction, inhibiting acetylcholine release from presynaptic nerve endings. This leads to muscle relaxation in three phases: binding, internalization, and inhibition of neurotransmitter release. Clinically, BTX treats muscle spasticity linked to central nervous system disorders such as stroke, brain injury, spinal cord injury, cerebral palsy, and multiple sclerosis. Preclinical studies indicate that BTX inhibits neuromodulator and transmitter secretion, which is important for sensory pathway neurotransmission, potentially reducing neuropathic pain. While BTX shows promise for peripheral neuropathic pain, its therapeutic effects on central neuropathic pain are less proven.

• 1
  BTX inhibits the secretion of substance P and CGRP from dorsal root ganglion (DRG) neurons, reduces the expression of TRPV1 and P2X3 receptors, and induces a central effect through retrograde axonal transport, all of which contribute to its potential analgesic effects.
• 2
  Studies suggest that BTX can have a central antinociceptive effect through retrograde axonal transport, where the toxin or its components are transported back to the spinal cord and brainstem, influencing pain processing at the central level.
• 3
  Clinical studies have shown that BTX can be effective in treating neuropathic pain associated with spinal cord injury, post-stroke shoulder pain, and complex regional pain syndrome, suggesting its potential as a treatment option for these conditions.