Spinal Cord Stimulation
Indication: CRPS, PVD, low back pain, angina
The spinal cord stimulation (SCS) (dorsal column stimulation) utilizes an electrodes placed in the epidural space, immediately behind the spinal cord, to stimulate the dorsal column of the spinal cord. The exact mechanism of SCS is unclear. However, it is believed that the gate-control theory of pain conduction plays a major role. When the dorsal column of the spinal cord is stimulated, it may attenuate the conduction of the pain signal on the spinothalamic tract through collateral inhibition. Inhibitory neurotransmitters such as gamma- aminobutyric acid (GABA) may also be involved.
SCS is indicated for failed back surgery syndrome, complex regional syndrome, and unremitting pain due to peripheral vascular disease. Recent studies have indicated that SCS may also improve pain caused by a refractory angina and improve circulation in the coronary arteries. Some authors have reported treatment of severe peripheral neuropathy and post-herpetic neuralgia with SCS. The value of SCS for amputation stump pain, phantom limb pain and spinal cord injury is yet to be established. Patients seeking spinal cord stimulator treatments usually have failed all the other conservative treatments, such as medication, physical therapy, and nerve blocks with anesthetics and/or corticosteroids. The spinal cord stimulator is not indicated for severe depression.
Patients should have a SCS trial prior to permanent implantation. During the trial, a percutaneous lead is inserted through the skin into the epidural space. Once the tip of the lead reaches the appropriate level, it is connected to an external pulse generator. When the stimulator is turned on, the patient feels tingling and numbness. If the painful area is covered by the stimulation, the pain is decreased by more than 50% and the patient is satisfied with the stimulation, a permanent implantation may be considered. The procedure of permanent implantation of the SCS is performed by pain specialists or neurosurgeons in operating room.
It requires a percutaneous insertion of an electrode into the epidural space under the guidance of fluoroscopy. The tip electrode is threaded up to T9 to T11 level in the epidural space immediately behind the dorsal column for the treatment of low back and leg pain. The other end of the electrode is connected through a subcutaneous tunnel to an internal pulse generator buried under the skin in the low back or abdominal wall. The strength of the stimulation can be changed through a remote control. Common complications of spinal cord stimulator implantation include infection, moving of the electrodes, and failure of pain relief, even after a “satisfied” trial. Serious complications, such as spinal cord compression, or epidural abscesses are rare.