Spinal cord stimulator
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2008-07-11T23:49:07Z
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'''Spinal Cord Stimulator''' (SCS) or '''[[Posterior column-medial lemniscus pathway|Dorsal Column]] Stimulator''' (DCS) is an implantable [[medical device]] used to treat chronic pain of neurologic origin. An electric impulse generated by the device near the dorsal surface of the spinal cord provides a [[paresthesia]] ("tingling") sensation that alters the perception of pain by the patient. A pain medicine specialist or a [[surgeon]] introduces the spinal cord stimulator lead into the [[epidural space]] either by [[percutaneous]] approach or by surgical [[laminectomy]] or [[laminotomy]]. A pulse generator or RF receiver is implanted in the abdomen or buttocks. A wire harness connects the lead to the pulse generator.
[[Image:SCS.jpg|thumb|right|Spinal cord stimulator leads in [[Thoracic vertebrae|thoracic spine]]]]
==History==
First report of a spinal cord stimulator implantation was in 1967 by Shealy.<ref>{{cite journal | author=Shealy CN, Mortimer JT, Reswick, JB | title=Electrical Inhibition of pain by stimulation of the dorsal columns: Preliminary Clinical Report | journal=Anesth Analg | year=1967 | pages=489–91 | volume=46 | pmid=4952225 | doi=10.1213/00000539-196707000-00025}}</ref> Studies since then have demonstrated efficacy of SCS in relieving select chronic pain disorders including [[failed back syndrome]], [[complex regional pain syndrome]] and [[peripheral neuropathy]].
Randomized controlled trials have shown efficacy of spinal cord stimulator in [[failed back syndrome]].<ref>{{cite journal | author=North RB, Ewend MG, Lawton MT, Kidd DH, Piantadosi S | title=Failed back surgery syndrome: 5-year follow-up after spinal cord stimulator implantation | journal=Neurosurgery | year=1991 | pages=692–9 | volume=28 | issue=5 | pmid=1831547}}</ref>
==Surgical Procedure==
Complications are generally related to the surgical procedure and can include lead migration, [[infection]], [[epidural hematoma]], [[paralysis]], dural tap, and in extremely rare cases, [[death]]. The possibility of lead migration is lessened when placed by laminectomy.<ref>{{cite journal | author=Villavicencio AT, Leveque JC, Rubin L, Bulsara K, Gorecki JP | title=Laminectomy versus percutaneous electrode placement for spinal cord stimulation | journal=Neurosurgery | year=2000 | pages=399–405; discussion 405–6 | volume=46 | issue=2 | pmid=10690729 | doi=10.1097/00006123-200002000-00025}}</ref>
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.
==Cautions==
Patients with SCS units are not able to have [[Magnetic resonance imaging|MRI]] procedures due to heating of the implanted electrodes, which can cause spinal cord damage. Other medical scans such as [[ultrasound]], [[CT]] and plain [[x-ray]] can be performed.
People with SCS should avoid areas or tasks near '''strong''' [[electromagnetic interference]] such as electricity substations and [[arc welding]].
==Types of Equipment==
There are three types of SCS units:
* Conventional Implantable Pulse Generator (IPG) consists of a battery and control electronics. When the battery wears out, it is surgically replaced.
* Rechargeable Implantable Pulse Generator (IPG) consists of a rechargeable battery and control electronics. The battery is recharged by an external device worn for a few hours every two to three weeks.
* [[Radio Frequency]] (RF) device consists of an implanted receiver and a transmitter device worn like a cell phone. The transmitter sends RF energy to the receiver which in turn sends stimulation to the lead. RF units have traditionally been used for patients that require high-power settings that would quickly deplete a primary-cell IPG (conventional IPG).
The patient is provided a remote control to turn on and off the stimulator, and depending on the device and the surgeon's preference, allows for limited programming of the stimulation patterns. The surgeon has a programming device that provides a wide range of stimulation settings.
==Current and Voltage Configuration==
SCS comes in constant current, variable voltage ([[Boston Scientific]] and [[St. Jude Medical|ANS]]) or constant voltage, variable current ([[Medtronic]]). A distinction is also made with respect to the number of independent power sources incorporated within the device. The are single source devices and multiple-source devices. Medtronic manufactures single-source voltage-controlled systems, ANS manufactures single-source current-controlled systems, and Boston Scientific manufactures 16-source current-controlled systems. The manufacturers disagree over the relative efficacy of their respective current and voltage configurations.
==Proposed mechanisms of action==
Among the proposed mechanism of action of SCS in pain relief include <ref>{{cite journal | author=Oakley JC, Prager JP | title=Spinal cord stimulation: mechanisms of action | journal=Spine | year=2002 | pages=2574–83 | volume=27 | issue= | pmid=12435996 | doi=10.1097/00007632-200211150-00034}}</ref>
* "closing of the gate" by the antidromic activation of large-diameter afferent fibers (see [[gate theory|gate-control theory of pain]])
* 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 influces on lower segments
* suppression of [[wide-dynamic-range neuron|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 [[migraine]]s. The leads are implanted in the bilateral suboccipital region.<ref>{{cite journal | author=Matharu MS, Bartsch T, Ward N, Frackowiak RS, Weiner R, Goadsby PJ | title=Central neuromodulation in chronic migraine patients with suboccipital stimulators: a PET study | journal=Brain | year=2004 | pages=220–30 | volume=127 | issue=Pt 1 | pmid=14607792 | doi=10.1093/brain/awh022}}</ref>
==Celebrities using spinal cord stimulators==
* [[Jerry Lewis]] has a spinal cord stimulator for his intractable low back pain and is a spokesperson for [[Medtronic]].<ref>[http://www.webmd.com/content/chat_transcripts/1/103993.htm Jerry Lewis: "My Journey Through Pain"]</ref>
* [[Michael Roman]], a chronic pain sufferer who had his leg amputated due to an infection, is now restarting his career as a professional racecar driver. Roman was implanted with the Precision system, and his racing team is sponsored by [[Boston Scientific]].
==See also==
*[[Transcutaneous Electrical Nerve Stimulator]]
==References==
<references/>
==Additional references==
* {{cite journal | author=Mailis-Gagnon A, Furlan AD, Sandoval JA, Taylor R | title=Spinal cord stimulation for chronic pain | journal=Cochrane Database Syst Rev | year=2004 | pages=CD003783 | volume= | issue=3 | pmid=15266501 | doi=10.1002/14651858.CD003783.pub2}}
* {{cite journal | author=North RB, Kidd DH, Farrokhi F, Piantadosi SA | title=Spinal cord stimulation versus repeated lumbosacral spine surgery for chronic pain: a randomized, controlled trial | journal=Neurosurgery | year=2005 | pages=98–106; discussion 106–7 | volume=56 | issue=1 | pmid=15617591}}
==External links==
* [http://www.controlyourpain.com Boston Scientific], a manufacturer
* [http://www.ans-medical.com/patient/basicsofscs/index.cfm Advanced Neuromodulation Systems], a manufacturer
* [http://www.medtronic.com/ Medtronic], a manufacturer
* [http://www.raceagainstpain.com Race Against Pain], a chronic pain support website
[[Category:Medical equipment]]
[[Category:Surgery]]
[[Category:Neuroprosthetics]]
[[Category:Neural engineering]]
[[Category:Neurotechnology]]
[[Category:Body modification]]
[[de:Rückenmarkstimulation]]
[[fr:Boîtier de neuromodulation]]