Spinal cord stimulation as a treatment for addiction to nicotine and other chemical substances

A new method for suppressing chemical substance craving comprises an electrical stimulation of the spinal cord using one or more implantable leads containing at least two conducting electrodes. The method may be used to suppress craving for alcohol, narcotics, cocaine, and amphetamines. The method is particularly suited to the suppression of nicotine craving.

BACKGROUND OF THE INVENTION
 The present invention relates to a new method for suppressing chemical
 substance craving comprising electrical stimulation of the spinal cord
 using one or more implantable leads containing at least two conducting
 electrodes. The method may be used to suppress craving for alcohol,
 narcotics, cocaine and amphetamines. The method is particularly suited to
 the suppression of nicotine craving.
 Tobacco related deaths are the largest single cause of premature death in
 developed countries. More than 400,000 deaths per year are linked to
 smoking related illness in the U.S. alone. However, despite the well
 publicized risks and consequences associated with tobacco use, more than
 25% of adults in the United States continue to smoke with prevalence rates
 varying according to demographics.
 The benefits of smoking cessation are substantial. Immediate benefits
 accrue to smokers who quit, including those with smoking-related disease.
 The risk of disease declines with smoking cessation and continues to drop
 through periods of abstinence. After 10-15 years of abstinence, mortality
 risks are equal to those of non-smokers. Smoking cessation decreases the
 risk of stroke, aortic aneurysm, peripheral vascular disease and
 myocardial reinfarction in individuals with myocardial infarction. Similar
 risk reduction exists in the incidence of smoking related cancers, chronic
 obstructive pulmonary disease and pregnancy related complications. An
 effective treatment for smoking addiction would result in a significant
 public health advance.
 Previous attempts to effect smoking cessation can be divided into two
 categories, non-pharmacologic interventions and pharmacologic
 interventions. Non-pharmacologic interventions focus on altering the
 behavioral conditioning of smokers so that smoking is avoided or is a
 disfavored activity. Pharmacologic interventions are geared toward
 lessening the craving for nicotine and are divided into the current
 mainstay, nicotine replacement therapy (the only pharmacologic therapy
 with FDA approval) and other forms of drug therapy. The patented
 pharmacologic therapies employ transdermal azapirones (U.S. Pat. Nos.
 5,837,280; 5,817,679; 5,633,009), nicotine receptor agonists and
 antagonists (U.S. Pat. Nos. 5,817,331; 5,691,365), nicotine lozenge (U.S.
 Pat. Nos. 5,662,920; 5,549,906), cotinine (U.S. Pat. No. 5,612,357),
 transdermal nicotine systems including subsaturated prolonged activity
 patches (U.S. Pat. Nos. 5,004,610; 4,839,174), and methods for
 anticholinergic blockage of withdrawal symptoms (U.S. Pat. No. 4,555,397).
 Unfortunately, as discussed below, none of the varied therapies, whether
 used singly or in combination, are very effective.
 The effectiveness of various methods for smoking cessation was studied and
 reported in a large meta-analysis derived from 188 randomized controlled
 trials evaluating multiple interventions intended for smoking cessation
 (See Law, M. An Analysis of the Effectiveness of Interventions Intended to
 Help People Stop Smoking. Archives Internal Medicine. 1995;
 155:1933-1941). In the meta-analysis, previously investigated
 interventions were evaluated and their outcomes given.
 The meta-analysis found that even the most effective therapies (nicotine
 replacement) showed a marginal success rate of 13%. No other therapy or
 therapies in combination showed success rates of greater than 5% except in
 the rare instance of special risk groups (pregnant women, patients with
 ischemic heart disease or previous myocardial infarction) who exhibited up
 to an 8% quit rate when given advice and encouragement to quit based on
 their special risk. Non-pharmacologic therapies fared poorly with the
 success rates no greater than that achieved with physician advice. More
 recently, a Mar. 2, 1999 New York Times article indicated new success
 using a combination therapy with sustained buproprion, nicotine
 replacement and counseling, citing an Oct. 23, 1997 article in the New
 England Journal of Medicine (Vol. 337, No. 17, pg. 1195). However, despite
 initial promise, one year follow-up cessation rates were 24.4% at the
 highest buproprion dose compared to 10.5% cessation rate for placebo. This
 rate advantage over placebo was consistent with the poor success rate
 using other methods. These low success rates illustrate the limitations
 and failures of the prior interventions and highlight the need for
 improved treatments to effect smoking cessation.
 Clearly, there exists a real need in the art for effective therapies and
 specifically more effective non-pharmacologic therapies in the treatment
 of nicotine addiction. There is also a need in the art to develop
 non-pharmacologic therapies for the treatment of addictions to other
 chemical substances such as alcohol, narcotics, cocaine and amphetamines.
 SUMMARY OF THE INVENTION
 The present invention relates to a method for treating addiction to
 nicotine and other chemical substances comprising electrical stimulation
 of the spinal cord or nervous system of the patient using one or more
 commercially available implantable spinal cord stimulation leads for a
 time period sufficient to suppress or extinguish the nicotine craving of
 the patient. The inventive method may be used either alone or in
 combination with drug or behavioral therapies.
 The effectiveness of the inventive method is believed to be related to the
 presence of nicotine receptors in the spinal cord which can be activated
 by spinal cord stimulation. Receptor and receptor systems, nerve and nerve
 endings of varying size, and neurotransmitters are distributed at all
 levels in the spinal cord. In particular, nicotine receptors are found in
 the central nervous system (brain and spinal cord) and analgesia is
 produced by nicotine both systemically and in the spinal cord. Potential
 mechanisms proposed for the production of analgesia by spinal cord
 stimulation suggest that stimulation of the dorsal horn of the spinal cord
 activates endogenous inhibitory systems which can modulate or block the
 sensation of pain. These inhibitory systems include, but are not limited
 to, endorphin and enkephalin systems (opiate systems), serotonergic,
 adenosingergic, adrenergic, dopinamergic and finally cholinergic systems.
 Nicotine receptors are found within the cholinergic system. Stimulation of
 the cholinergic (inhibitory) systems in the spinal cord produces
 antinociception (pain relief). Therefore, stimulation of the cholinergic
 and thereby the nicotinic system in the spinal cord should also mimic the
 presence of nicotine by activating the nicotinic receptors, but by a
 non-pharmacologic method. Thus, stimulation of the nicotinic system should
 mimic nicotine both systemically and locally in the central nervous
 system. As a net result of this stimulation, a patient treated with spinal
 cord stimulation should experience decreased craving for nicotine and an
 ability to interrupt behavioral components thereby allowing the patient to
 overcome the addiction.
 The inventive method uses one or more implantable leads which are comprised
 of a plurality of conducting electrodes adapted for accurate placement
 within the human body, in particular the area of the spinal cord or
 nervous system to be stimulated. Various devices for spinal cord
 stimulation used in chronic pain management and movement disorders are
 disclosed in U.S. Pat. Nos. 3,654,933, 4,044,77, 4,379,462, 5,058,584,
 5,417,719, 5,501,703 and 5,643,330 which are all herein incorporated by
 reference in their entirety.
 The method described is also applicable to the treatment of addiction to
 alcohol, narcotics, cocaine. amphetamines and other chemical substances
 since receptor systems (e.g. opiate receptors for narcotics) specific for
 these substances are also found in the spinal cord.
 In clinical practice, the suitability of the inventive method for a
 particular patient is determined by first screening the patient using
 various psychological criteria to determine if he is a suitable candidate
 for the procedure. If the patient passes the screening procedure, a trial
 implantation and stimulation is carried out. The results of the trial are
 then evaluated. If the patient demonstrates successful suppression or
 extinction of nicotine craving as a result of the implantation and
 stimulation, the lead or leads are then permanently implanted in the
 patient.

DETAILED DESCRIPTION OF THE INVENTION
 The basic elements needed for the method and application of spinal cord
 stimulation for suppression of chemical substance craving, in particular,
 nicotine, comprise a spinal cord stimulator lead and a power source
 connected to the lead to enable conduction of electrical impulses to the
 spinal cord. The spinal cord stimulator lead contains external contact
 electrodes at the distal tip which send impulses into the spinal cord.
 These distal contact electrodes are independently connected to
 corresponding contact terminals at the proximal end of the lead by
 separate stranded wires which run substantially parallel to each other.
 The proximal conductive terminals are in turn connected to an electrical
 power source through a lead extension connector which makes individual
 contact with the proximal lead terminals and allows transmission of
 electrical signals from the power source to the distal lead electrodes.
 The generator or electrical source provides electrical stimulation and
 allows for the selective and independent variation of characteristics of
 the electrical power including amplitude, frequency rate (heretofore
 referred to as "rate") and pulse width, as well as variation in the
 polarity of the conducting electrode contacts within the lead (any number
 of lead contacts from four to eight to sixteen in current technology). If
 technologically feasible, in an alternative embodiment, the lead extension
 connector may be omitted and the electrical power source connected
 directly to the proximal conductive terminals.
 The amplitude of the electrical power may be varied between about zero
 volts to about fifteen volts and is chosen to be as high as can be
 tolerated by the patient so as to achieve maximum stimulation. Preferably,
 the voltage is varied between about 0.1 volts to about eight volts. More
 preferably, the voltage is varied between about zero volts to about six
 volts and most preferably, the voltage is varied between about zero to
 about four volts. The pulse width of the electrical power may also be
 varied at the same time as one or more of the characteristics of the
 electrical power or may be separately varied with the other
 characteristics held constant. Preferably, the pulse width is varied
 between about zero to about 450 microseconds. More preferably, the pulse
 width is varied between about 180 to about 270 microseconds and most
 preferably, the pulse width is varied between about 240 to about 270
 microseconds. The rate of the electrical power may also be varied at the
 same time as one or more of the characteristics of the electrical power or
 may be separately varied with the other characteristics held constant.
 Preferably, the rate is varied between about zero to about 150 cps. More
 preferably, the rate is varied between about 25 to about 80 cps and most
 preferably, the rate is varied between about 50 to about 80 cps.
 The number of leads implanted ranges from one lead to ten leads.
 Preferably, the number of leads implanted ranges from one lead to four
 leads. More preferably, the number of leads implanted ranges from one lead
 to two leads. Most preferably, the number of leads implanted is two.
 Preferably, the lead or leads are inserted into the epidural space of the
 spinal cord and contact the external portion of the dura to stimulate the
 neural structures underneath. The lead or leads may be inserted into the
 sacral, caudal, lumbar, thoracic or cervical spines. The position of the
 implanted lead or leads ranges from the sacral position to the high
 cervical position of the spinal cord. Preferably, the lead or leads are
 implanted from the upper lumbar to the lower cervical position in the
 spinal cord. More preferably, the lead or leads are implanted from the
 lower thoracic to the higher thoracic position of the spinal cord. Most
 preferably, the lead or leads are implanted from the lower thoracic to the
 middle thoracic position in the spinal cord. The lead or leads are
 positioned so that the lead or leads are parallel to the midline of the
 spinal cord and may be positioned to the right of the midline, directly on
 the midline or to the left of the midline. The lead or leads may also be
 placed oblique or transverse to the midline. If more than one lead is
 implanted, the leads may be positioned both to the right and left of the
 midline of the spinal cord.
 All lead contacts and conductors are electrically insulated by a suitable
 insulating material which is safe for implantation in the human body. The
 distal contact electrodes may have variable contact surface area as well
 as variable spacing between electrodes. The number of electrodes may be
 varied as well. Current technology allows a total of 16 electrodes to
 receive electrical transmission from a single energy source. For example,
 four quadripolar (four electrode) leads may be connected to a single power
 source or two eight electrode leads may be connected to a single power
 source. The number of electrodes per lead ranges from between at least two
 to sixteen electrodes per lead. Preferably, the number of electrodes per
 lead ranges from between four to eight per lead. Most preferably, the
 number of electrodes per lead is four. If multiple leads are implanted,
 the number of electrodes per lead may be the same or different.
 Electrode polarity refers to activation of lead electrodes by assigning
 positive or negative charge to the electrode. Polarity can include as few
 as two electrodes per lead (one positive, one negative) on up to as many
 electrodes as are contained on the lead (with at least one electrode
 positive and at least one electrode negative). Systematic electrode
 polarity assignments are made during trial stimulation beginning with the
 second and third most distal electrodes (in a four electrode system) as
 postive and negative respectively. Additional electrodes are added or
 substituted to improve coverage area and maximize stimulation. The lead or
 leads are positioned so that optimum stimulation occurs without using the
 most distal/proximal electrodes which allows these electrodes to be used
 in the event of lead migration (i.e., these electrodes can be activated if
 the lead moves up or down the spine respectively).
 Variation in the polarity of the electrodes is achieved by activating at
 least two electrodes per lead up to the maximum number of electrodes
 contained on the lead. Preferably, the number of electrodes activated per
 lead ranges from at least two up to eight electrodes per lead. More
 preferably, the number of electrodes activated per lead ranges from at
 least two up to four electrodes per lead. Most preferably, three
 electrodes are activated per lead.
 Lead electrode systems may be percutaneous as described in U.S. Pat. No.
 4,004,774 or wider (paddle) systems may be inserted surgically through a
 laminotomy or laminectomy incision as described in U.S. Pat. Nos.
 3,822,708, and 3,654,933 which are hereby incorporated by reference in
 their entirety. If multiple leads are implanted, they may be inserted at
 the same or different levels and used for more complete stimulation
 coverage.
 Examples of totally external power systems include those systems which are
 used for temporary trial stimulation. Internally implanted systems include
 totally implanted generators or can include implanted receivers which are
 internalized but which receive input from an external power source
 transmitted through antennae. The external systems are radiofrequency
 power sources which may be used for patients with higher energy
 requirements.
 FIG. 1 illustrates three different leads, a four-electrode percutaneous
 lead 50 (FIG. 1a), an eight-electrode percutaneous lead 60 (FIG. 1b) and a
 surgically implanted lead 70 (FIG. 1c). Four-electrode lead 50 comprises
 an insulated tube with a distal end 50a and a proximal end 50b with four
 external conducting electrodes at the distal end 50a as previously
 described. A first external conducting electrode 1 is positioned most
 distal on the lead (closest to the distal tip). A second external
 conducting electrode 2 is positioned a given distance proximally from
 external conducting electrode 1. A third conducting electrode 3 and a
 fourth conducting electrode 4 are respectively spaced at given distances
 proximal to electrode 2. The eight electrode lead 60 comprises a distal
 end 60a and a proximal end 60b. The lead 60 further comprises external
 conducting electrodes 1', 2', 3', 4' at the distal end 60a as described
 for lead 50 above and additionally comprises a fifth conducting electrode
 5', a sixth conducting electrode 6', a seventh conducting electrode 7' and
 an eighth conducting electrode 8' as illustrated in FIG. 1b. In the
 surgical lead 70, the lead comprises a distal end 70a and a proximal end
 70b. The lead 70 illustrated in FIG. 1c further comprises disc-shaped
 external conducting electrodes 1", 2", 3" and 4" at the distal end 70a.
 These electrodes are of greater size and have a larger conduction surface
 than the comparable structures in the percutaneous leads depicted in FIGS.
 1a and 1b.
 The proximal end 50b of lead 50 comprises tube-conducting terminal
 connections, 9, 10, 11 and 12 which are connected by individually stranded
 wire running substantially parallel but separately. 9, 10, 11 and 12
 extend to and are in contact with external conducting electrodes 1, 2, 3
 and 4 respectively. The proximal end 60b of lead 60 comprises
 tube-conducting terminal connections 9', 10', 11', 12' and additionally
 comprises tube-conducting connecting terminal connections 13', 14', 15'
 and 16' which are connected by individual separate stranded wires to
 external conducting electrodes 1', 2', 3', 4', 5', 6', 7' and 8'
 respectively. The proximal end 70b of surgical lead 70 comprises tube
 conducting terminal connections 5", 6", 7" and 8" which are connected by
 individual separate stranded wires to external conducting electrodes 1",
 2", 3" and 4" respectively. An insulating material 17 is interposed
 between each of the conductors on all three leads 50, 60 and 70 and exists
 throughout the lead.
 FIG. 2 illustrates in schematic the basic elements of the spinal cord
 stimulation system. Lead 50 comprises distal end 50a and proximal end 50b.
 Lead extension connector 19 is comprised of a distal end 19a and a
 proximal end 19b. Lead extension connector 19 is fitted to the proximal
 end 50b of lead 50 through the distal end 19a of the lead extension
 connector 19. This connection is made with tube conducting terminal
 connections 9, 10, 11 and 12 at the proximal end 50b of lead 50 fitting
 inside and surrounded by corresponding circular terminal connections 19c,
 19d, 19e, and 19f on the distal extension connector. Distal extension
 connector terminals 19c, 19d, 19e and 19f contain tightening screws which
 are fastened using an alien wrench tool provided by the manufacturer. Each
 of terminal connections 19c, 19d, 19e and 19f connects to the
 corresponding tube conducting terminal connections of the proximal lead 9,
 10, 11 and 12 and each in turn corresponds to a distal external conducting
 electrode 1, 2, 3 and 4 in the distal lead. For example, terminal
 connection 19c is connected to tube conducting terminal connection 9 which
 is in turn connected to distal external conducting electrode 1.
 The proximal end 19b of the lead extension connector 19 terminates in prong
 connectors 19g and 19h which fit into the source of energy transmission 20
 (in this case an internal power source generator such as Medtronic 7425
 Itrel 3). Prong 19g and 19h fit snugly into receptacle outlets 20a and 20b
 within the energy source. Prong connectors 19g and 19h are tightened with
 two external screws per prong connector or energy source receptacles using
 an allen wrench tool provided by the manufacturer.
 Several possible sources of energy transmission are also illustrated in
 FIG. 2. The decision for which energy source is optimum for each
 individual patient is based on the energy needs and coverage area. In use,
 implanted systems especially those running multiple leads, use larger
 amounts of energy and subsequently the internal generator battery must be
 replaced more frequently. External radiofrequency energy sources
 transmitted through antennae to internal implanted receivers have the
 ability to run multiple lead systems, and can run multiple channels as
 well, i.e., two separate leads can receive two separate programs. A
 totally implanted energy source generator with the capability for multiple
 channels (i.e. different programs for different leads) may also be used.
 A totally implantable internalized generator 20 is shown in FIG. 2. An
 energy system with internalized receiver 21 which has input for the
 proximal end of the lead extension similar to 19b is also illustrated. In
 this embodiment, energy is transmitted through an externally placed
 antenna 22 with impulses transmitted through the skin of the patient to
 the receiver 21. When the energy source is an external transmitter 23,
 electrical impulses are transmitted from 23 through the antenna 22 through
 the skin to the internalized receiver 21 through the lead extension
 connector 19 to the spinal cord stimulator lead proximal end 50b and
 finally to the distal end 50a where stimulation is transmitted to the
 spinal cord. Implanted receiver 21 is inserted into and enclosed by the
 human body in identical fashion as the implanted generator 20 (assuming
 compatible component lead or leads and lead extension connector(s)). In
 this embodiment, compatible proximal lead extension connector 19b is
 inserted into receiver 21 which is implanted under the skin. The
 connection is made by inserting compatible prong connectors 19g and 19h
 into compatible inlets 21a and 21b respectively. Antenna 22 is then placed
 on the skin externally, overlying the implanted receiver 21 and is
 connected to the external generator 23. The connection is made by
 inserting compatible antenna prong connectors 22a and 22b into external
 generator inlets 23a and 23b respectively. In operation, radiofrequency
 energy is transmitted from external generator 23 through the antenna 22
 into the internalized receiver 21. Radiofrequency signals are converted to
 electrical energy and transmitted through compatible lead extension
 connector 19 into the lead 50 which stimulates the neural structures
 underneath.
 A number of issues must be addressed in selecting the best stimulation
 system for a particular patient. The first decision is whether to place a
 percutaneous or surgical lead for trial and/or permanent implantation.
 Percutaneous leads are advantageous in that they are less invasive to
 place, but they tend to cover a smaller area of stimulation and are more
 likely to migrate. These problems can be overcome with the placement of
 multiple lead systems with more electrodes for stimulation as well as dual
 channel systems which provide versatility in programming or with surgical
 leads for permanent implantation. The second decision which must be made
 is whether to use an internal or an external power source. Internal power
 sources are less cumbersome to the patient, but are more likely to need
 replacement for battery life at high output and are not currently capable
 of providing dual or multi-channel stimulation. The third decision
 involves the appropriate selection of the number of leads placed and the
 number of electrodes per lead. As mentioned, multiple leads with multiple
 channels and multiple electrodes can overcome problems with coverage area
 and migration and can enable transverse stimulation with dual channel
 systems. Finally, single or multichannel systems must be chosen. Any
 system may be a viable option to provide stimulation for smoking
 cessation, with some possible advantages with certain systems (see
 preferred embodiment).
 Patient Screening
 Before using spinal cord stimulation for smoking cessation, the
 appropriateness of the therapy must be determined for each patient. This
 determination includes the patient presenting with a history of smoking
 refractory to other methods (i.e. prior relapse following attempted
 cessation). A psychological interview (similar to those conducted for pain
 management by spinal cord stimulation) is also necessary to evaluate the
 patient's psychological status and to prepare them for the implantation of
 foreign material. The interview should include the administration of an
 MMPI (Minnesota Multiphasic Psychological Inventory) which measures ten
 scales including hypochondriasis, depression, conversion/hysteria,
 psychopathic deviate, masculinity, femininity, paranoia, psychastenia,
 schizophrenia, hypomania, and social introversion. The MMPI also includes
 validity scales which test for consistency in answering. The MMPI is the
 gold standard of psychological tests and is the most frequently used test
 for patient screening prior to spinal cord stimulation. In addition, the
 90-R symptom checklist is a fast and easy test measuring somatization,
 depression, anxiety, anger, and paranoia. The Beck Depression Inventory,
 Spielburg State Trait Anxiety Inventory, Chronic Illness Problem Inventory
 and Oswestry Disability Questionnaire may also be used in addition to the
 psychological interview. The Fagerstrom Tolerance Questionnaire and the
 Fagerstrom Test for Nicotine Dependence may be used to assess degree of
 nicotine dependence. Suggested exclusion criteria for implantable
 technology (as with pain management) include active psychosis, measured
 uncontrolled depression or anxiety, active suicidal behavior, active
 homicidal behavior, and serious cognitive deficits such as those found in
 dementia or severe sleep disturbances.
 Spinal Stimulation Trial
 Before using the method, the patient will first undergo a screening trial
 of spinal cord stimulation to determine if the patient is a suitable
 candidate for this procedure. The screening trial comprises percutaneous
 placement through an epidural needle of a temporary trial lead into the
 epidural space overlying the dura and spinal cord. Trial screening may
 also be performed through surgical incision but this method of placement
 is an overly extensive procedure in the event of a failed trial. The
 screening trial may also include the implantation of multiple leads with
 multiple electrodes. Leads may be placed along the spinal cord axis
 (parallel to the spinal cord), oblique to the spinal cord axis, or
 transverse to the spinal cord axis according to methods well know in the
 art of pain management.
 In the screening trial, the patient is first taken into the operating room
 and placed prone on the operating room table. Using fluoroscopic guidance,
 the spinal levels are identified. The patient is prepped and draped in
 sterile fashion. The needle is inserted percutaneously into the epidural
 space using fluoroscopic guidance as well as the loss of resistance
 technique or whatever method was previously used for epidural needle
 placement. The spinal cord stimulator lead is passed under fluoroscopic
 guidance into the epidural space overlying the spinal cord until the
 desired position is achieved.
 FIG. 3a illustrates epidural needle 24 inserted between spinous processes
 25 and passing through ligamentum flavum 26 into the epidural space 27.
 The distal position of the lead in the cord is identified as 28. The
 distal lead electrodes overlie the dura 29 and the spinal cord 30. The
 needle passes through skin 31. FIG. 3a illustrates the lead placement in
 the side or sagittal view. The anterior posterior view in FIG. 3b
 illustrates the epidural needle placed at the midline 24b or in paramedian
 fashion 24b'.
 FIG. 4a illustrates a lead 50 placed at the midline of the spinal cord with
 the tip at the level of the eighth thoracic vertebral level T8. In FIG.
 4b, two eight-electrode leads 60 and 60' are both placed in the spinal
 cord with lead 60 passed the eighth thoracic vertebral level T8 and 60'
 passed the ninth thoracic vertebral level T9. This configuration could
 also be achieved with 2 four electrode leads or a combination. Leads 60
 and 60' may be connected to the same or separate power sources and receive
 identical or individual programs from the same or different power sources.
 The two eight-electrode leads 60 and 60' placed in the spinal cord
 represent an example of a multi-electrode array system.
 After placement in the spinal cord, the trial lead or leads are connected
 to an external generator power source via a lead extension connector 19
 which is disposable. Variations in amplitude are administered from 0 to 15
 volts, variations in pulse width from 0-450 .mu.s, variations in rate from
 0-150 cps (Hz) and variations in electrode polarity (i.e.
 positive/negative polarity in the first, second, third, fourth, fifth,
 sixth, seventh, etc., conducting electrodes). The stimulation trial begins
 with basic settings in polarity with the second most distal lead negative
 and the third most distal lead positive with a rate of 80 and a pulse
 width of 270. The amplitude is slowly increased from 0 volts until
 stimulation is detected by the patient. Amplitude requirements are highly
 variable and depend on both the position of the lead or leads and the
 contact quality.
 Stimulation is detectable when the patient experiences tingling in areas of
 skin in the back and lower extremities in the case of a thoracic or lumbar
 spinal cord stimulation, in the areas of skin in the abdomen and chest
 wall with upper thoracic stimulation or in the areas of skin in the upper
 extremity and upper chest wall in the case of cervical spinal stimulation.
 To ensure the lead is placed along the dorsum of the spinal cord (and thus
 stimulating the dorsal horn), the sensory feeling of tingling is
 preferable over the motor feeling of pulling or muscle twitching. Dorsal
 placement may also be verified fluoroscopically. The lead may be
 superficially fastened to the skin (e.g., with a single suture and sterile
 barrier dressing) for easy removal at the end of the trial. Alternatively,
 the lead may be partially internalized. The latter procedure involves
 extending the needle puncture site into a small incision, anchoring the
 lead to the spinous ligaments with suture and tunnelling a temporary lead
 extension connector to a distal exit site. The partial internalization
 procedure preserves the lead for permanent use (the temporary connector is
 discarded) but requires a more extensive removal procedure in the event of
 a failed trial.
 The screening trial may extend from about 3 to about 10 days or more with
 frequent evaluation of smoking habits. The evaluations will comprise
 subjective reports from the patient of smoking craving and a tally of the
 number of cigarettes smoked. The evaluations may also include objective
 evidence such as biochemical markers, preferably exhaled CO or saliva
 cotinine. At the end of the screening trial, a decision on whether on not
 to permanently implant the lead will be made based on criteria for
 success. These criteria will include significant diminution of craving,
 significant decreased intake of cigarettes (less than 50% intake of prior
 habit) and minimal or no withdrawal symptoms. Withdrawal symptoms may be
 subjective and compared to previous quitting attempts and interventions
 used. If the screening trial is considered successful, then the patient
 will proceed with permanent implantation of the spinal cord stimulator
 system. Permanent implantation may include removal of the trial screening
 lead (or leads) and subsequent re-implantation of a new spinal cord
 stimulator lead (or leads), power source and internal lead extension
 connector. Or the permanent implantation procedure may include
 internalization of the trial screening lead (or leads) if this lead (or
 leads) was anchored and tunneled (i.e. partially internalized to remain
 sterile) during the trial.
 Permanent implantation of the spinal cord stimulator lead or leads after a
 successful screening trial comprises the placement of a permanent spinal
 cord stimulator lead or leads (similar or identical to the trial lead if
 percutaneously placed, paddle lead if placed through laminotomy).
 Placement of the permanent lead or leads is performed by the same method
 used for implantation of the trial screening lead (if percutaneous not
 laminotomy). In the permanent implantation procedure, the patient is taken
 to the operating room and placed in the prone position with fluoroscopic
 guidance as described for the screening trial procedure. The spinal level
 selected is similar but not necessarily identical to the trial screening
 level in the sacral, lumbar, thoracic or cervical areas. A spinal cord
 stimulator lead or leads are placed as described for the screening trial
 procedure. Once stimulation reproduces the stimulation observed with the
 trial lead or leads, the percutaneous insertion sites are extended as an
 incision using a scalpel to include the sterile lead extension connector
 pocket. Alternatively, laminotomy or laminectomy may be performed with
 placement of a surgical lead. A distal site is selected for permanent
 generator or receiver implantation and a tunnel is made from the midline
 incision (where lead placement occurs) to the distal pocket site for the
 energy source.
 As illustrated in FIG. 5, the lead extension connectors pass through the
 tunnel to form a connection between the proximal end of the spinal cord
 stimulator lead and the power source generator or receiver as described
 previously. The proximal end of spinal cord stimulator permanent lead 50b
 extends from a midline incision 36. A tunnel 37 is made from the midline
 incision 36 to a distal pocket site commonly made in the upper buttocks
 38, in the anterior abdomen 38a or the upper chest 38b in cervical
 stimulation. Lead extension connector distal connector site 19a is
 connected to the proximal end of the spinal cord stimulator lead 50b and
 the proximal end of the lead extension connector 19b is connected to the
 internal energy source (or receiver) 20 (or 21) which lies in the distal
 pocket.
 Connections are made at the midline site between the spinal cord stimulator
 lead or leads and the lead extension connector(s). Connections are also
 made between the lead extension connector or connectors and the receiver
 generator or generators as power source. Electrical stimulus is now
 provided with an internal system after closure of the midline incision and
 distal pocket site or sites. This system is now internalized and will
 reproduce the successful results of the trial period. Changes in generator
 settings are performed by telemetry using an external compatible
 programmer. Alternatively, an implanted receiver with external power
 source transmitted to the receiver via an external antenna may be used for
 the permanent implantation. In this system, the receiver is implanted
 identically to the internal generator and is connected to the lead
 extension connector which connects to the lead. In this manner an external
 power source transmits electrical stimulation power through the antenna to
 the internal receiver which transmits the energy into the lead. The
 advantage of this system is primarily prolonged life as batteries are
 easily changed in the external system and therefore can be practically
 used for higher energy levels.
 In a permanent implantation, the implanted lead or leads may remain in
 place for a time period between about one month to about ten years.
 Shorter time periods are also possible. For example, the implanted lead or
 leads may remain in place for a time period between about one year to
 about five years. The time period of implantation may also extend between
 about one year to about two years.
 The patient is followed up immediately post-implantation according to
 standards for routine post-operative care and wound checks (approximately
 two times per week for the first week). The target quit date for smoking
 is set as the day of implantation. To monitor the treatment, the patient
 keeps a diary to record cigarette intake as well as withdrawal symptoms.
 Symptoms of nicotine withdrawal include craving for cigarettes, depressed
 mood, insomnia, irritability, anger, anxiety, difficulty concentrating and
 increased appetite. The patient is seen twice a week for the first week,
 once per week for the next seven weeks and then once per month through the
 end of the first year. The success of the treatment is defined as greater
 than 50% reduction in the number of cigarettes smoked per day sustained to
 six months post quit date followed by complete cessation of smoking at the
 one year mark and sustained for a period of six months. Success criteria
 are evidenced by the patient report of cigarette number verified by
 concurrent reduction/elimination of exhaled carbon monoxide and saliva
 cotinine. Side effects should decrease over the course of the first year
 and are expected to be minimal by the end of that year.
 Stimulation may also be terminated for a time period between about one day
 to about six months to evaluate the possibility of explantation of the
 lead or leads. Other time periods may be used for this evaluation,
 including a time period between about two weeks to about three months and
 a time period between about one month to about two months.
 The inventive method for treating addiction to tobacco products is
 nondestructive and reversible, does not involve any pharmacologic agents
 and its use of a trial screening period predicts the success of permanent
 implantation. An attractive feature of the inventive method is its ability
 to be integrated into combinations with other therapies currently in use
 for smoking cessation. Although marginally successful, combination
 therapies have still shown the best success in achieving smoking
 cessation. The combination of spinal cord stimulation with pharmacologic
 therapy (both nicotine and non-nicotine) and behavioral programs is the
 preferred combination and should significantly increase the success of
 what have here-to-now been historically unsuccessful programs. Spinal cord
 stimulation may also be combined with pharmacologic therapy alone or with
 behavioral programs alone. Multicomponent behavioral programs contemplated
 for combination with spinal stimulation alone in combination with
 pharmacologic therapy include aversive techniques, coping strategies and
 relapse prevention. Pharmacologic treatments contemplated for combination
 with spinal cord stimulation alone or in combination with behavioral
 programs include antidepressant medication (e.g., bupropion) as well as
 nicotine replacement therapy using gum, patches or lozenges. Nicotine
 fading may also be used. By combining various therapies, physiologic
 dependence on nicotine should be maximally reduced since its withdrawal
 would be tolerated physically and behavioral problems would be addressed
 to improve patient coping and prevent relapse.
 Given the variety of available leads, lead systems, power sources and
 procedural combinations, many approaches are possible and viable for use
 in treatment of tobacco addiction. However, the approach with the most
 advantages (and thus the preferred embodiment) is as follows.
 Patient eligibility is designated by initial criteria of need combined with
 psychological testing and evaluation as described above. A percutaneous
 trial is preferably performed with one or two four-electrode (quadripolar)
 leads placed through an epidural needle. Most preferably, two leads are
 employed in the trial. The leads are not tunneled but are externalized to
 external lead extension connectors and a screening power source. Insertion
 of the leads are in the low thoracic or high lumbar region and the leads
 are placed to the area of the sixth to tenth thoracic vertebrae. Dual
 channel stimulation is performed for the trial which allows individual
 programs to be used for each lead. This combination also allows for the
 most versatility in setting combinations as well as "cross talk"
 (transverse stimulation) between individually programmed leads.
 In the preferred embodiment, the trial period lasts from seven to ten days
 with evaluation visits on the third, sixth and tenth day of the trial.
 Success is assessed by determining the extent to which the patient's
 nicotine dependence has been suppressed or extinguished. One way to
 monitor the patient's progress is by observing the number of cigarettes
 smoked per day before and after the trial. The exhaled carbon monoxide and
 saliva biochemistry (cotinine) levels maintained by the patient before and
 after the trial may also be used to monitor the success of the procedure.
 Trial leads are removed around the tenth day and if success parameters are
 met, permanent implantation is scheduled. Permanent implantation consists
 of similar lead placement compared to the trial leads with two quadripolar
 leads placed. The preferred power source is an external power source
 transmitting radiofrequency energy through an antenna to an internal
 receiver. The advantage of this approach is that the patient is spared a
 surgical procedure with percutaneous trial and lead removal and subsequent
 permanent implantation is minimally invasive. In addition, the two lead
 system gives the most versatility in parameters as well as in broad-based
 coverage and the duality of leads can compensate for lead migration.
 Finally, the advantage of an external power source enables not only dual
 channel (lead individuality in programming), but also enables the use of
 higher power levels without concern for battery rundown. Based on the
 following case report, energy levels may be higher and coverage area
 needed more broad than that needed for pain management.
 Improvements of the device and method may include the use of multiple lead
 types, electrode numbers, multi-channel leads placed, paddle leads,
 multiple generator input of multiple leads for single generator, multiple
 generators, implanted receivers with external power sources connected to
 single or multiple leads with various number of electrodes. Settings for
 these leads may be identical as when inserted into single generator power
 source or may be independent of each other. There can be transmission from
 one lead electrode to another electrode on the same lead or there can be
 transmission from lead electrode or electrodes on a single lead to
 electrodes on a different lead or to multiple other leads.
 Computer programs may also be used to program a complex network for
 transmission between multiple leads and multiple-lead electrodes for the
 maximum transmission into and through the spinal cord. This can be
 performed at multiple levels including low lumber up to high cervical with
 most likely positive results being in the mid to low thoracic area.
 Electrode polarities from distal to most proximal two electrode, four
 electrode, eight electrode, and even higher electrode numbered systems can
 vary polarity positive to negative in each of the two, four, eight,
 sixteen electrodes with all permutations of positive and negative
 included. Any electrode on a given lead can transmit and communicate to
 any electrode on a separate lead in combination with polarity changes and
 multiple permutations. Besides electrode polarity, placement of single or
 separate leads in addition to covering all levels of the spinal cord may
 comprise two or more separate locations within the spinal cord. For
 example, one lead may be placed low lumbar with another lead placed
 thoracic with communication between the two leads or independent
 stimulation between the two leads. Paddle lead systems may be inserted
 through laminotomies or percutaneously (if feature variations are made),
 and these may be used independently, with multiple paddle leads or with
 combinations of percutaneous leads.
 As note above, the settings for electrical stimulation include amplitude,
 rate and pulse width along with polarity of contact electrodes.
 Additionally, the current art for spinal cord stimulation includes
 continuous mode stimulation or cycling mode stimulation. Continuous mode
 stimulates continuously and may be required long-term for optimal results.
 Cycling mode stimulation is available in cycles which automatically
 stimulates on and off times in varying durations. This can significantly
 increase the battery life in totally implanted systems. In addition to
 continuous and cycling modes, biphasic stimulation is available which
 allows electrode polarity to reverse with every pulse. The previously
 mentioned are part of cycling modes. Single stimulation, dual stimulation
 and multiple electrode stimulation arrays are also available. This allows
 stimulation of single lead of 4, 8 or 16 electrodes (projected greater
 number of electrode leads to become available). Dual stimulation provides
 different stimulation programs for separate channels for the generator
 power source to two sets of electrodes (two four-electrode leads, two
 eight-electrode leads), or differing stimulation to the two sets of four
 electrodes or two sets of eight-electrode leads. Pulse width, amplitude
 and rate are the same for both channels. Future variations will provide
 versatility in multiple lead systems of any electrode number.
 Application of the inventive method is illustrated with the example set
 forth below. In this case, the patient required a high degree of
 stimulation as evidenced by the significant feelings of tingling and
 stimulation in his legs combined with a subjective feeling of motor
 weakness. This may represent the required level of stimulation for smoking
 cessation or could indicate this particular patient to be one of a
 difficult population.
 EXAMPLE 1
 A 48 year-old male presented with a greater than ten year history of severe
 chronic lower back and leg pain status post extensive lumbar spinal
 surgery with laminectomy and fusion but continued pain in his low back and
 bilateral legs. The pain did not follow any dermatomal distribution
 indicating discrete nerve root involvement. Rather his symptoms were
 consistent with arachnoiditis with lower extremity radiculitis.
 The patient was refractory to multiple interventions, both psychological,
 physical, pharmacological and procedural. These included local injections
 in the muscle and fascia, epidural injections, nerve root injections,
 external electrical stimulation (transcutaneous electrical nerve
 stimulation), lumbar facet injections, injection at the fusion site,
 cryoneurablation, high dose chronic opiate therapy, physical therapy of
 all types, and psychological pain management techniques. The patient was
 considered to be a good candidate for spinal cord stimulation applying
 prior art spinal cord stimulation for pain management.
 The patient was taken to the operating room and lay prone on the operating
 room table and subsequently underwent placement of a trial screening
 spinal cord stimulator electrode. This involved insertion into the spinal
 interspace at T12-L1 and insertion of a percutaneous four-electrode system
 lead into the epidural space. The lead was advanced until the distal tip
 lay at the level of T8 at the midline. The proximal end was connected to
 an external power source and manipulated until the patient could feel
 tingling (stimulation) in both of his legs. The lead was secured at its
 percutaneous insertion site with #3.0 silk and an occlusive dressing. The
 patient was discharged home with an external power source, Medtronic's
 external power source Model No. 3625 with variations available for
 amplitude, pulse width and rate. The patient's electrode polarity was
 electrode 0 most distal electrode as the positive pole and electrode 2 the
 third most distal electrode as the negative electrode. Amplitude ranged
 2.5-8.0 during the trial period with a pulse width of 300 (range 100-450)
 and a rate of 50 (range 25-120). The patient underwent a one-week trial
 period with the implanted lead during which time he was seen three times
 in the outpatient clinic.
 The patient reported only a mild decrease of his pain symptoms during the
 first clinic visit. At this point, electrode polarities were changed to
 include 0 positive, 2 negative, 3 positive. The patient reported that he
 felt strong stimulation in his legs to the point where he may have been
 experiencing some motor component and weakness in his legs. Strength was
 normal by gross motor testing and he was able to walk without assistance.
 The patient was seen twice more during the trial period. At the end of a
 one-week trial period, the patient reported that his pain symptoms were
 decreased in both of his legs but unfortunately his low back pain was only
 marginally affected. This report of pain relief resulted in the assessment
 that less than 50% of the patient's total pain symptoms were decreased by
 spinal cord stimulation and he thus failed the screening trial for
 permanent implantation based on pain management.
 However, the patient made a notable observation which he reported at the
 end of the trial. The patient self-reported a heavy smoking habit of many
 years duration (two packs per day for greater than 25 years) but observed
 that he had no craving to smoke cigarettes during the entire trial. The
 patient reported that on the third day of the trial, he realized that he
 had not thought about smoking a cigarette for three days. The patient
 further reported that he had not smoked any cigarette for the entire
 duration of the trial nor did he note any significant withdrawal symptoms.
 The patient reported simply that he had "forgotten all about having to
 smoke". The patient also observed that he had made many previous
 unsuccessful efforts to quit smoking using conventional interventions such
 as nicotine containing gum. However, upon removal of the trial lead, the
 patient reported that his cravings returned in one day after spinal cord
 stimulation was discontinued.
 While the invention has been illustrated and described in detail in the
 drawings and foregoing descriptions, the same is to be considered
 illustrative and not restrictive in character. All changes and
 modifications that come within the spirit of the invention are
 contemplated as within the scope of the invention.
 If the inventive method is used to suppress craving for other chemical
 substances such as alcohol, the target quit date is again selected as the
 day of implantation. To monitor the treatment, the patient keeps a diary
 to record substance intake and any withdrawal symptoms specific to the
 chemical substance. Success criteria are chose to be compatible with
 established success criteria for that chemical substance.