Postherpetic & Deafferentation Pain

When the nervous system loses its normal input

"Deafferentation" pain arises when nerves are damaged or disconnected from the spinal cord and brain, and the deprived nervous system begins to generate pain on its own. It is typically burning or crushing, and it is characteristically difficult to treat. Importantly, it generally does not respond to simply cutting a pain pathway, so the approach is specific to each syndrome. Common forms include:

• Postherpetic neuralgia
  Persistent burning pain in an area of skin after a shingles outbreak, lasting long after the rash has healed.
• Phantom limb pain
  Pain felt in a limb that has been amputated, sometimes severe and persistent.
• Brachial plexus avulsion pain
  Severe, often crushing or burning pain after the nerve roots supplying an arm are torn from the spinal cord, usually in a high-energy injury.

After medication, matched to the syndrome

Medication for nerve pain is the starting point, and for postherpetic neuralgia, early shingles treatment and vaccination help prevent it. Surgery is considered for severe, refractory pain, and the procedure is chosen specifically for the type of deafferentation pain, because these conditions respond to targeted approaches rather than to general pain operations.

Surgical options

• DREZ (dorsal root entry zone) lesioning
  Precise lesions made where the damaged nerve roots enter the spinal cord, calming the abnormal activity generated there. It is the established procedure for the severe pain of brachial plexus avulsion, and is used for some pain after spinal cord injury.
• Neuromodulation (spinal cord stimulation)
  In selected cases of postherpetic or phantom limb pain, stimulation that reshapes the pain signal can help. As always, it is trialed before any permanent implant.
• Motor cortex or deep brain stimulation
  For certain refractory central and deafferentation pain, stimulation of the motor cortex or deep brain targets can modulate the pain network. These are specialized options reserved for carefully selected patients.

See also