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Electrical Stimulation Therapy for Pain Relief and Management
Chapter
8
Electrical Stimulation Therapy for Pain Relief and Management 8.1 OCCIPITAL NERVE STIMULATION Occipital nerve stimulation (ONS) uses electrical pulses for the relief of chronic migraines, the cause of which is not clearly understood but is thought to be neurovascular in nature and brought about by external physiological or environmental triggers. Headaches and migraines are usually defined as chronic if they last for more than 15 days per month for more than 3 months. Primary headaches are defined as having no obvious underlying pathological problems whereas secondary headaches exhibit underlying pathological problems. The occipital region of the brain lies at the posterior toward the back of the skull and is innervated by the greater and lesser occipital nerves, which have their origins in the cervical roots, C2 and C3. The mechanisms by which ONS can relieve symptoms of chronic headache are not completely understood but electrical stimulation therapy of the greater occipital nerve has been shown to provide some relief for those suffering with chronic migraines.
8.2 ST JUDE MEDICAL IMPLANTABLE PULSE GENERATORS FOR ONS OF THE OCCIPITAL NERVES The Implantable Pulse Generators (IPGs) from St Jude Medical provide a range of electrical therapy treatments for intractable which is chronic migraine from simple pain management (Genesiss) to sustained pain therapy stimulation using nonrechargeable (Eon Ct) and rechargeable (Eons and Eons Mini) devices. Figure 8.1 shows the Eons Minit, the smallest IPG in the range.
Implantable Electronic Medical Devices. DOI: http://dx.doi.org/10.1016/B978-0-12-416556-4.00008-5 © 2015 Elsevier Ltd. All rights reserved.
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■ FIGURE 8.1 Eon
Minit. (Copyright ª St Jude Medical. Printed with permission.)
All of the IPGs monitor therapy requirements and deliver efficient power management using proprietary NeuroDynamict technology. The IPGs incorporate constant current source outputs such that any change detected in the electrode-neural impedance results in an adjustment of the output voltage in order to maintain a constant applied electrical stimulation field. The percutaneous leads consist of either four or eight electrode contacts which are placed in contact with the occipital nerve. An external Rapid Programmert system incorporates MultiSteeringt technology to help locate the desired stimulation area and effectively steer the electrode current to that area to optimize the delivered stimulation therapy. The Eons Minit product does not have FDA approval for use in the United States.
8.3 BOSTON SCIENTIFIC PRECISION SPECTRAt SCS SYSTEM Figure 8.2 shows the Precision Spectrat SCS rechargeable system which is used to provide pain relief for patients who suffer with chronic pain. The system consists of an IPG which is implanted in the abdomen, lower buttock or below the clavicle and an implantable electrode array
8.3 Boston Scientific Precision Spectrat SCS System
■ FIGURE 8.2 Precision Spectrat SCS. (Copyright ª Boston Scientific. Reprinted with permission.)
implanted alongside the spinal cord, consisting of 32 contacts arranged as either four 8-contacts or two 16-contact leads, allowing for greater coverage area. Electrical impulses sent to the electrodes are perceived as a smooth tingling sensation known as paresthesia so that the feeling of pain may be reduced.
■ FIGURE 8.3 Placement of epidural electrodes. (Copyright ª Boston Scientific. Reprinted with permission.)
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The electrode array is inserted using an epidural needle so that the electrode contacts cover the dorsal columns of the spinal cord where stimulation is required (Figure 8.3). The IPG incorporates Multiple Independent Current Control (MICC) technology whereby each electrode contact has its own independent power source so that electric fields can be set up between electrodes. The IPG is current controlled and provides an automatic adjustment of stimulation voltage at each electrode in order to provide a constant current when the neural impedance interface changes due to scar tissue formation after implantation. The external remote control is used to program the IPG via an inductively coupled RF telemetry link to provide up to four stimulation areas per program with up to 16 possible stimulation programs, allowing patients to target and control their own pain management therapy for different pain problems and different postures at different times of the day. The system is programmed by proprietary Illumina 3Dt software which takes into account the complex three-dimensional environment in which the leads exist. The algorithm incorporates three-dimensional lead location and creates a customized stimulation field designed to improve pain targeting. LeadSynct Technology is able to detect relative lead location and adjusts for lead offset by synchronizing contacts on parallel leads. It has been designed to account for relative lead movement during the trial, after the permanent implant, or during the procedure. The IPG incorporates an internal Zero-Voltt rechargeable battery which does not suffer from battery failure when completely discharged and can last up to 5 years, depending on parameters and usage. The battery is externally charged by placing the battery charger over the site of the IPG.
8
Electrical Stimulation Therapy for Pain Relief and Management 8.1 OCCIPITAL NERVE STIMULATION Occipital nerve stimulation (ONS) uses electrical pulses for the relief of chronic migraines, the cause of which is not clearly understood but is thought to be neurovascular in nature and brought about by external physiological or environmental triggers. Headaches and migraines are usually defined as chronic if they last for more than 15 days per month for more than 3 months. Primary headaches are defined as having no obvious underlying pathological problems whereas secondary headaches exhibit underlying pathological problems. The occipital region of the brain lies at the posterior toward the back of the skull and is innervated by the greater and lesser occipital nerves, which have their origins in the cervical roots, C2 and C3. The mechanisms by which ONS can relieve symptoms of chronic headache are not completely understood but electrical stimulation therapy of the greater occipital nerve has been shown to provide some relief for those suffering with chronic migraines.
8.2 ST JUDE MEDICAL IMPLANTABLE PULSE GENERATORS FOR ONS OF THE OCCIPITAL NERVES The Implantable Pulse Generators (IPGs) from St Jude Medical provide a range of electrical therapy treatments for intractable which is chronic migraine from simple pain management (Genesiss) to sustained pain therapy stimulation using nonrechargeable (Eon Ct) and rechargeable (Eons and Eons Mini) devices. Figure 8.1 shows the Eons Minit, the smallest IPG in the range.
Implantable Electronic Medical Devices. DOI: http://dx.doi.org/10.1016/B978-0-12-416556-4.00008-5 © 2015 Elsevier Ltd. All rights reserved.
107
108
CHAPTER 8 Electrical Stimulation Therapy for Pain Relief and Management
■ FIGURE 8.1 Eon
Minit. (Copyright ª St Jude Medical. Printed with permission.)
All of the IPGs monitor therapy requirements and deliver efficient power management using proprietary NeuroDynamict technology. The IPGs incorporate constant current source outputs such that any change detected in the electrode-neural impedance results in an adjustment of the output voltage in order to maintain a constant applied electrical stimulation field. The percutaneous leads consist of either four or eight electrode contacts which are placed in contact with the occipital nerve. An external Rapid Programmert system incorporates MultiSteeringt technology to help locate the desired stimulation area and effectively steer the electrode current to that area to optimize the delivered stimulation therapy. The Eons Minit product does not have FDA approval for use in the United States.
8.3 BOSTON SCIENTIFIC PRECISION SPECTRAt SCS SYSTEM Figure 8.2 shows the Precision Spectrat SCS rechargeable system which is used to provide pain relief for patients who suffer with chronic pain. The system consists of an IPG which is implanted in the abdomen, lower buttock or below the clavicle and an implantable electrode array
8.3 Boston Scientific Precision Spectrat SCS System
■ FIGURE 8.2 Precision Spectrat SCS. (Copyright ª Boston Scientific. Reprinted with permission.)
implanted alongside the spinal cord, consisting of 32 contacts arranged as either four 8-contacts or two 16-contact leads, allowing for greater coverage area. Electrical impulses sent to the electrodes are perceived as a smooth tingling sensation known as paresthesia so that the feeling of pain may be reduced.
■ FIGURE 8.3 Placement of epidural electrodes. (Copyright ª Boston Scientific. Reprinted with permission.)
109
110
CHAPTER 8 Electrical Stimulation Therapy for Pain Relief and Management
The electrode array is inserted using an epidural needle so that the electrode contacts cover the dorsal columns of the spinal cord where stimulation is required (Figure 8.3). The IPG incorporates Multiple Independent Current Control (MICC) technology whereby each electrode contact has its own independent power source so that electric fields can be set up between electrodes. The IPG is current controlled and provides an automatic adjustment of stimulation voltage at each electrode in order to provide a constant current when the neural impedance interface changes due to scar tissue formation after implantation. The external remote control is used to program the IPG via an inductively coupled RF telemetry link to provide up to four stimulation areas per program with up to 16 possible stimulation programs, allowing patients to target and control their own pain management therapy for different pain problems and different postures at different times of the day. The system is programmed by proprietary Illumina 3Dt software which takes into account the complex three-dimensional environment in which the leads exist. The algorithm incorporates three-dimensional lead location and creates a customized stimulation field designed to improve pain targeting. LeadSynct Technology is able to detect relative lead location and adjusts for lead offset by synchronizing contacts on parallel leads. It has been designed to account for relative lead movement during the trial, after the permanent implant, or during the procedure. The IPG incorporates an internal Zero-Voltt rechargeable battery which does not suffer from battery failure when completely discharged and can last up to 5 years, depending on parameters and usage. The battery is externally charged by placing the battery charger over the site of the IPG.