Case Study 10—Programmer for Implanted Stimulators
Chronic pain in the lower back and legs may be treated in several different ways. Since the 1980s, one particular form of treatment has gained favor-electrical stimulation of the spinal cord, which blocks pain signals traveling up the spinal cord to the brain. A small but important market has grown for implanting these stimulators in patients with chronic pain. After release from the hospital, a patient may program the desired stimulation through a transmitter that encodes parameters and then couples them through radio frequency (RF) to the implant. Figure 13.1 illustrates the general configuration. Adjusting the stimulator for each patient, however, is extremely tedious
because there are many possible combinations of parameter values. Just eight electrodes represent 6050 combinations of polarity, while 16 electrodes represent over 62 million possible combinations. A sophisticated programmer/transmitter, for use by medical staffs and patients, can ease the burden of adjustment by selecting appropriate subsets of stimulation parameters from the wide variety available. The programmer that my company designed was a pentop computer that allows patients to tailor their own treatment by drawing simple lines and touching screen buttons. Figure 13.2 shows a prototype of such a programmer. The programmer was to be used primarily by patients in physicians’
offices. A physician or assistant taped the programmer’s antenna over the site of the implant, set up the session on the programmer, and then handed the programmer to the patient. Patients responded to simple instructions and answered questions posed on the screen; they also drew outlines of where they felt both pain and stimulation effects. The programmer was intuitive and very easy for patients to use; patients
were intimately involved in their own treatment, an important factor. It reduced the time spent by medical personnel to adjust stimulators from hours to minutes. The data were more reliable.