Pain Management: Stimulation and Intraspinal Pump

Spinal Stimulators and drug pumps are examples of advanced stereotactic neurosurgery techniques offered board-certified neurosurgeons as part the latest medical and surgical advances at a comprehensive pain management center. Here, a multi-disciplinary team, including board-certified physicians practicing neurology, neurological surgery, neurological oncology, radiation oncology, and neuroradiology, works together to achieve the very best treatment for our patients.

The use of electrical stimulation of deep brain structures and the spinal cord to relieve debilitating chronic pain is known as neuroaugmentation. This treatment may be able to provide considerable pain relief (though not necessarily complete), but alternative treatment modalities, such as medication and physical therapy, should first be tried first because of the level of involvement and degree of patient motivation and commitment that is required.

Spinal Stimulation

Spinal cord stimulators and spinal pumps are implantable systems which are used to treat a variety of conditions including pain and spasticity as well as to deliver therapeutic agents. Use of these neuroaugmentation modalities is growing through advances in technology and effectiveness and greater education of patients and physicians as to their availability, options, and indications.

Modern spinal cord stimulators are programmable so that once implanted, the signal can be adjusted for optimal pain relief.

Spinal stimulation has provided pain relief in people suffering from multiple sclerosis, low back pain, amputated limbs, herpes, and spinal cord injury.

• Prior to placing an implantable spinal cord stimulator, typically the patient receives a trial of a temporary stimulator to assess the efficacy of stimulation in providing pain relief for that patient.
• The placement of the electrode is performed under local anesthesia and allows testing of its effectiveness during the procedure.
• The surgical procedure involves placing a compact generator in the lower anterior abdomen wall and connecting a wire to a strip of electrodes placed adjacent to the back part of the spinal cord.
• Through low-voltage electrical stimulation of the electrodes, the normal pain signals which travel in the posterior parts of the spinal cord are altered to provide partial or complete pain relief from conditions such as cancer pain, post-spinal cord injury pain, and pain from reflex sympathetic dystrophy (RSD).
• Recipients of spinal cord stimulators are educated on the use and programming of their device.

Intraspinal Pumps

Since the initial attempt to infuse an anesthetic agent into the spinal epidural space (the area surrounding the spinal cord and nerve roots) in 1976, a number of technological, surgical, and pharmaceutical advances have revolutionized the treatment of:

• Chronic and intractable pain
• Spasticity
• Cancer chemotherapy and hormonal therapy, and
• A variety of other conditions that can benefit from long-term direct infusion of a compound into the epidural space

Typically, the surgery involves placing a reservoir under the skin of the lower anterior abdomen. At the same time, from the back a catheter is placed into the spinal epidural space and then tunneled under the skin to connect to the reservoir. Thus the contents of the reservoir, typically morphine (to treat pain) or baclofen (for spasticity), can be delivered to the epidural space in a controlled fashion via the pump in the reservoir. The reservoirs can be refilled as necessary. To determine if a patient would be a good candidate for a spinal pump, a trial injection via a lumbar puncture is performed. Patients whose pain or spasticity is relieved are considered for placement of a pump. In addition to pain and spasticity, spinal epidural pumps can be used as a number of other applications such as chemotherapy and hormonal therapy.

Deep Brain Stimulation

Deep brain stimulation has been successfully utilized in the management of patients with several different kinds of pain, including pain associated with spinal cord injury, nerve injury, stroke, herpes, and cancer. The body's pain mechanisms are mediated by substances known as beta endorphins, which are produced by certain brain cells. These beta endorphins act to inhibit pain by their influence on two areas of the brain called the periventricular gray matter and the periaqueductal gray matter.

• The surgical procedure is performed under local anesthesia in the operating room. Computer-assisted imaging techniques, known as stereotaxy, are employed to identify the targets of stimulation.
• An electrode is carefully guided through a small hole made in the skull and passed to specific brain areas, which may be the periventricular or periaqueductal gray matter or brain regions known as the thalamic sensory nuclei.
• The other end of the stimulating electrode is connected to a battery-powered programmable device that is implanted under the skin below the clavicle.
• One potential drawback to this treatment modality is the development of tolerance, or diminished effectiveness over time. This possibility is diminished with the use of certain drugs and the avoidance of using continuous stimulation.