Practice Parameters for the Use of Spinal Cord Stimulation in the Treatment of Chronic Neuropathic Pain

Glossary & Acronyms

ANODE - a stimulating contact programmed as a positive pole, which attracts negative ions.

CATHODE - a stimulating contact programmed as a negative pole, which attracts positive ions.  Compared with an anode, a cathode more readily attains the amplitude stimulation threshold that initiates action potential generation (depolarization); thus, cathodal effects predominate in SCS. 

GUARDED CATHODE - an array in which two contacts programmed as anodes bracket a contact programmed as a cathode.  The boundary created by the anodes for the depolarizing effect of the cathode helps define the area of paresthesia.  In general (statistically), patients prefer a guarded cathode array.

CHANNEL - a multichannel generator allows simultaneous delivery of pulses of different amplitude to different contacts. (A programmable generator that allows rapid sequential delivery of pulses to different contacts is not, strictly speaking, a multichannel device; instead it is a “gated single channel” generator.) 

CONTACT - the electrically conductive portion of the electrode.  An individual contact can be programmed as an anode, a cathode, or neither (i.e., off).

CONTACT COMBINATION – anode or cathode or off assignment of contacts.

ELECTRODE - an assembly comprising contacts, wire, insulating spacers, catheter(s), and backing material.  “Electrode” is generally applied to the part of the assembly that contains the contacts (with “lead” used to describe the wire leading between the electrode and the power source).  Using “electrode” to refer solely to a contact is imprecise because it ignores the other components of the assembly.  Using “lead” to refer to an electrode is inappropriate; the electrode does not lead anywhere. 

ELECTRODE ARRAY – the arrangement of electrodes, which can (for example) be longitudinal or transverse; single, dual, or triple; end-to-end or parallel

LEAD - the insulated wire that connects (leads) the power source to the electrode contacts.  (This term is often, but confusingly, used to refer to an electrode assembly.) 

“MONOPOLAR” STIMULATION -  the misnomer “monopolar stimulation” (stimulation, of course, requires two poles) refers to the use of the metallic case of an implanted generator as a remote anode.  Thus, the electrode has only one contact that is stimulated (i.e., one pole) as a cathode.

PARESTHESIA - a tingling sensation caused by SCS.  In order for SCS to provide pain relief, it is generally necessary for the paresthesia to overlap the pain.  Such overlap, however, does not guarantee pain relief.  Achieving pain/paresthesia overlap is, thus, a necessary, but not sufficient, condition for pain relief. 

PERCUTANEOUS CATHETER ELECTRODE – an electrode that can be inserted through a needle, in a manner that is less invasive than laminectomy/laminotomy.

SURGICAL PLATE/PADDLE ELECTRODE - also known as a laminectomy, laminotomy, or insulated electrode.  Because of their shape, paddle or plate electrodes must be inserted via laminectomy or laminotomy.  Because they do not rotate, the dorsal surface can be insulated.  Because they are insulated, surgical plate/paddle electrodes reduce the incidence of extraneous stimulation, in particular that attributable to recruitment of dorsal structures.

STIMULATION PARAMETERS -  the amplitude, width, and repetition rate of stimulation pulses.  See also CONTACT COMBINATION.


Acronyms

ADL = Activities of daily living
FBSS = failed back surgery syndrome
MRI = magnetic resonance imaging
PHN = postherpetic neuralgia
PLS = phantom limb syndrome
Q of L = quality of life
RCT = randomized controlled trial
SCS = spinal cord stimulation
VAS = visual analogue scale