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Nine US institutions performed 14,807 Phase I‐II treatments of magnetic‐induction (Magnetrode [Henry Medical Electronics, Inc., Los Angeles, CA]) hyperthermia in 1170 adults. All had advanced tumors: 20% had untreated inoperable cancer or disease progression despite surgery (10%), radiation therapy (XRT) (3%), chemotherapy (27%), or combinations (40%); 67% had pain; and 79% had reduced activity. Eighteen percent were advanced primaries, 26% were recurrent, and 56% metastatic tumors in the head and neck (7%), body wall (7%), extremity (4%), abdominal cavity (17%), pelvis (17%), lung (15%), or liver (30%); 36% were < 5 cm and 64% ⩾5 cm. Treatments were to safe tolerance for 30 to 60 minutes for five or more treatments. Results in 960 evaluable patients were complete response 9% (1–34 months; median, 7 months), partial response 18% (1–39 months; median, 4 months), minimal response 10% (1–15 months; median, 3 months), and no change 33% (1–32 months; median, 3 months), with decreased pain in 30% and improved activity in 21%, independent of histologic type or site. Regression was dependent on treatment type and minimum temperature: heat only, 23%; heat + XRT, 60%; heat + less‐than‐standard XRT because of prior XRT failure, 39%, heat + intravenous (IV) chemotherapy, 28%; heat + same previously failed IV chemotherapy, 20%; heat + intraarterial (IA) chemotherapy, 28%; heat + same previously failed IA chemotherapy, 15%; heat + standard XRT + chemotherapy, 58%; heat + less‐than‐standard XRT + chemotherapy, 47%; < 40°C, 31%; 40 to 40.9°C, 45%; 41 to 41.9°C, 54%; 42 to 42.9°C, 47%; 43 to 43.9°C, 40%; 44 to 44.9°C, 33%; 45 to 45.9°C, 55%; 46 to 46.9°C, 63%; > 47°C, 100%. There were 49 (0.33%) skin burns and 2 systemic injuries (stomach ulcer at 1 month; lung fibrosis at 9 months). This trial indicates that localized hyperthermia has a significant role in palliation of human advanced solid cancer.

An experimental model has been used to study issues that are relevant to the use of electrical stimulation to help paralyzed individuals walk. Modulated stimulation sequences for the quadriceps muscles were manually selected using an iterative trial-and-error procedure to cause the knee angle to follow a specific movement pattern (desired trajectory). Four paraplegic subjects were tested before and after an eight-week program in which the quadriceps were exercised daily with electrical stimulation. It was found that 12.6 +/- 2.9 iterations were required to approximate the desired trajectory. The average error of the final match between the actual and desired trajectories was 2.1 degrees +/- 0.7. Repeated responses were extremely consistent; the average difference between successive trials was less than 1 degree in 81 percent of the trials. When the stimulation sequence was repeated every 3 s for 50 cycles, however, there was a progressive degradation in the response, even in exercised legs, that demonstrated the limitations of open-loop control. Stimulus modulation envelopes for all four subjects were similar in shape (although varied in amplitude) indicating that the iterative process can be shortened by starting with an "average" modulation envelope. Stimulation sequences achieved accurate matches of the desired trajectory on subsequent days when adjusted by a simple gain factor. The relevance of these results to multichannel control of walking is discussed.

Implanted electrical stimulation technology has changed greatly in the roughly five decades of its existence. Many factors determine the viability of the technology and whether the systems and products developed ultimately go on to help the target patient population. This article describes the successful introduction of an implanted system and the challenges to implanted system development, acceptance, and usability of these systems by the patient and clinical communities.