Intractable phantom limb pain syndrome: spinal cauda equina stimulation for alternative location of spinal cord stimulation
Phantom limb pain is a phenomenon in which patient experience pain in a part of the body that no longer exists but still feel pain due to the nerves present at the site of amputation which continue to send pain signals to the brain. Several modern treatments like spinal cord stimulation has been introduced for the management of intractable post-amputation pain.
From one of the recent survey, a 46 year old male patient complained of severe ankle and foot pain which had knee amputation surgery on the right side 3 years before. After multiple modalities for pain management involving numerous oral and intravenous medications, nerve blocks and pulsed radio frequency treatment, results were not acceptable. Temporary effect was observed. The use of spinal cord stimulation also did not provide complete satisfactory pain management of the phantom pain.
A randomized trial was conducted for the trial of cauda equina to stimulate the severe pain site and to observe pain scores. Cauda equina syndrome (CES) is a relatively rare but serious condition that describes extreme pressure and swelling of the nerves at the end of the spinal cord. CES results in low back pain and problems with bowel and bladder function with weaken legs.
In the study, a Tuohy needle was inserted through the L5-S1 interlaminar space and the tip of the lead was placed at the upper L4 vertebral body. After the stimulation of the cauda equina at the L4 and L5 levels, the patient's pain score was decreased. Stimulation parameters programmed were electrode, 1(+), 2(-), 3(-); amplitude 2.3 V; pulse width, 450 ms; rate, 40 Hz.
Satisfied results were observed after the stimulation process with cauda equina. The trial lead positioning in the cauda equina was able to stimulate the site of severe pain and patient's pain score was dramatically decreased. A successful pain management with spinal cauda equina stimulation has been recorded following the failure of spinal cord stimulation in the treatment of intractable phantom limb pain.