A
spinal cord stimulator (SCS), also known as a
dorsal column stimulator, (DCS) is an implantable
medical deviceA medical device is a product which is used for medical purposes in patients, in diagnosis, therapy or surgery. If applied to the body, the effect of the medical device is primarily physical, in contrast to pharmaceutical drugs, which exert a biochemical effect. Specific regional definitions of...
used to treat chronic
neurologicalNeurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
pain. An electric impulse generated by the device produces a
tingling sensationParesthesia is a sensation of tingling, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
that alters the perception. The device is implanted into the
epidural spaceIn the spine, the epidural space is the outermost part of the spinal canal. It is the space within the canal lying outside the dura mater...
either by
percutaneousIn surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an "open" approach where inner organs or tissue are exposed .The percutaneous approach is commonly used in vascular procedures...
approach or by surgical
laminectomyLaminectomy is a spine operation to remove the portion of the vertebral bone called the lamina. There are many variations of laminectomy, in the most minimal form small skin incisions are made, back muscles are pushed aside rather than cut, and the parts of the vertebra adjacent to the lamina are...
or
laminotomyA laminotomy is a neurosurgical procedure that removes part of a lamina of the vertebral arch in order to decompress the corresponding spinal cord and/or spinal nerve root....
. A pulse generator or RF receiver is implanted in the abdomen or buttocks.
A
spinal cord stimulator (SCS), also known as a
dorsal column stimulator, (DCS) is an implantable
medical deviceA medical device is a product which is used for medical purposes in patients, in diagnosis, therapy or surgery. If applied to the body, the effect of the medical device is primarily physical, in contrast to pharmaceutical drugs, which exert a biochemical effect. Specific regional definitions of...
used to treat chronic
neurologicalNeurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...
pain. An electric impulse generated by the device produces a
tingling sensationParesthesia is a sensation of tingling, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
that alters the perception. The device is implanted into the
epidural spaceIn the spine, the epidural space is the outermost part of the spinal canal. It is the space within the canal lying outside the dura mater...
either by
percutaneousIn surgery, percutaneous pertains to any medical procedure where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using an "open" approach where inner organs or tissue are exposed .The percutaneous approach is commonly used in vascular procedures...
approach or by surgical
laminectomyLaminectomy is a spine operation to remove the portion of the vertebral bone called the lamina. There are many variations of laminectomy, in the most minimal form small skin incisions are made, back muscles are pushed aside rather than cut, and the parts of the vertebra adjacent to the lamina are...
or
laminotomyA laminotomy is a neurosurgical procedure that removes part of a lamina of the vertebral arch in order to decompress the corresponding spinal cord and/or spinal nerve root....
. A pulse generator or RF receiver is implanted in the abdomen or buttocks. A wire harness connects the lead to the pulse generator.
History
Application of electrical current to the dorsal surface of the spinal cord was found to produce a state of analgesia. First report of a spinal cord stimulator implantation was in 1967 by Shealy. The analgesic effect of spinal epidural stimulation in man was first reported in 1971. Studies since then have demonstrated efficacy of SCS in relieving select chronic pain disorders including
failed back syndromeFailed back syndrome or post-laminectomy syndrome is a condition characterized by persistent pain following back surgeries.Failed back syndrome , also called "failed back surgery syndrome" , refers to chronic back and/or leg pain that occurs after back surgery. It is characterized as a chronic...
,
complex regional pain syndromeComplex regional pain syndrome is a chronic progressive disease characterized by severe pain, swelling and changes in the skin. The International Association for the Study of Pain has divided CRPS into two types based on the presence of nerve lesion following the injury.* Type I, also known as...
and
peripheral neuropathyPeripheral neuropathy is the term for damage to nerves of the peripheral nervous system, which may be caused either by diseases of the nerve or from the side-effects of systemic illness....
.
Randomized controlled trials have shown efficacy of spinal cord stimulator in
failed back syndromeFailed back syndrome or post-laminectomy syndrome is a condition characterized by persistent pain following back surgeries.Failed back syndrome , also called "failed back surgery syndrome" , refers to chronic back and/or leg pain that occurs after back surgery. It is characterized as a chronic...
.
Implantation
Complications are generally related to the surgical procedure and can include lead migration,
infectionAn infection is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host's resources to multiply, usually at the expense of the host. The infecting organism, or pathogen, interferes with the normal functioning of the...
,
epidural hematomaEpidural or extradural hematoma is a type of traumatic brain injury in which a buildup of blood occurs between the dura mater and the skull. The dura mater also covers the spine, so epidural bleeds may also occur in the spinal column...
,
paralysisParalysis is the complete loss of muscle function for one or more muscle groups. Paralysis can cause loss of feeling or loss of mobility in the affected area.-Causes:Paralysis is most often caused by damage to the nervous system, especially the spinal cord...
, dural tap, and in extremely rare cases,
deathDeath is the termination of the biological functions that define a living organism. It refers to both a particular event and to the condition that results thereby. The true nature of the latter has for millennia been a central concern of the world's religious traditions and of philosophical...
. The possibility of lead migration is lessened when placed by laminectomy.
A trial is usually done before the permanent unit is placed. A temporary percutaneous lead is used and is connected to an external pulse generator. The trial is from 3 to 7 days. If the patient has at least 50% improvement in pain during the trial, the patient is considered a candidate for the permanent unit.
Possible mechanisms
Among the proposed mechanism of action of SCS in pain relief include:
- "closing of the gate" by the antidromic activation of large-diameter afferent fibers (see gate-control theory of pain
The gate control theory of pain, put forward by Ronald Melzack and Patrick David Wall in 1962, and again in 1965, is the idea that the perception of physical pain is not a direct result of activation of nociceptors, but instead is modulated by interaction between different neurons, both...
)
- activation of supraspinal loops relayed by the brain stem or thalamocortical systems providing both ascending and descending inhibition
- activation of anterior pretectal nucleus which has descending pain inhibitory influences on lower segments
- suppression of wide-dynamic-range (WDR) neurons responsive to sensory input
- antidromic release of neuropeptides (substance P, calcitonin gene-related peptide, others) in the periphery which may be related to the modulation of small vessel diameter.
Other uses
SCS units have been used to treat patients with frequent
migraineMigraine is a neurological syndrome characterized by altered bodily perceptions, severe headaches, and nausea. Physiologically, the migraine headache is a neurological condition more common to women than to men. The word migraine was borrowed from Old French migraigne...
s. The leads are implanted in the bilateral suboccipital region.
Potential interference
Sources of strong electromagnetic interference (e. g.,
defibrillationDefibrillation is the definitive treatment for the life-threatening cardiac arrhythmias, ventricular fibrillation and pulseless ventricular tachycardia. Defibrillation consists of delivering a therapeutic dose of electrical energy to the affected heart with a device called a defibrillator...
,
dielectric heatersDielectric heating is the process in which radiowave or microwave electromagnetic radiation heats a dielectric material...
, electrocautery,
Magnetic resonance imagingMagnetic Resonance Imaging , or nuclear magnetic resonance imaging , is primarily a medical imaging technique most commonly used in radiology to visualize the internal structure and function of the body...
, radiofrequency ablation or
ultrasoundUltrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Although this limit varies from person to person, it is approximately 20 kilohertz in healthy, young adults and thus, 20 kHz serves as a useful lower limit in describing ultrasound...
) can interact with the spinal cord stimulation system, potentially damaging the unit or causing injury or death. An implanted cardiac device such as a cardiac
pacemakerA pacemaker is a medical device which uses electrical impulses, delivered by electrodes contacting the heart muscles, to regulate the beating of the heart...
or a defibrillator may also damage a spinal cord stimulator, and the electrical pulses from the spinal cord stimulator may result in an inappropriate response of the cardiac device.