A Dual-Mode Multifunctional Pulsed Radio-Frequency Stimulator for Trigeminal Neuralgia Relief and its Animal Model.

This work proposed a programmable pulsed radio-frequency (PRF) stimulator for trigeminal neuralgia (TN) relief on demand. The implantable stimulator is a miniaturized micro-system which integrates a wireless interface circuit, a sensor interface circuit, a PRF pattern generation circuit and a logic controller. The multifunctional stimulator capable of delivering current/voltage stimulation provides the choice of the biphasic sinusoidal, square and patterned waveform for PRF treatment researches. The external handheld device can wirelessly transmit the parameters of frequency, amplitude, pulse duration and repetition rate of the pulse train to the implanted stimulator. While stimulating, the temperature sensor can monitor the operating temperature. The feedback signal is transmitted in medical implanted communication system (MICS). The micro-system is fabricated in a 0.35 µm CMOS process with a chip size of 3.1 × 2.7 mm2. The fabricated chip was mounted on a 2.6 × 2.1 cm2 test board for studying the in vivo efficacy of pain relief by PRF. Animal studies of PRF stimulation and commonly-used medication for trigeminal neuralgia are also demonstrated and the presented results prove that PRF stimulation has greater effectiveness on trigeminal neuralgia relief comparing to the medication. The effectiveness period lasts at least 14 days. The results of neural recording show that the PRF stimulation of trigeminal ganglion (TG) attenuated neuron activities without being severely damaged. Pathology also revealed no lesion found on the stimulated area.

Two Transcutaneous Stimulation Techniques in Shoulder Pain: Transcutaneous Pulsed Radiofrequency (TPRF) versus Transcutaneous Electrical Nerve Stimulation (TENS): A Comparative Pilot Study.

Objective: To compare the safety and efficacy of 2 transcutaneous stimulation techniques, transcutaneous pulsed radiofrequency (TPRF) versus transcutaneous electrical nerve stimulation (TENS), in chronic shoulder tendonitis. Design: A prospective, randomized, and double-blind clinical trial. Setting: Academic pain service of a city hospital. Subjects: Fifty patients with sonography-confirmed shoulder tendonitis. Methods: Fifty patients were randomly allocated into two groups for electrical stimulation treatment with 3-month follow-ups: Group 1 (n=25), TENS and Group 2 (n=25), TPRF. Both groups underwent either treatment for 15 minutes every other day, three times total. Our primary goals were to find any treatment comfort level, adverse event, and changes in Constant-Murley shoulder (CMS) scores. The secondary goals were finding the changes in pain, enjoyment of life, and general activity (PEG) scores. Results: For primary goals, no adverse events were noted throughout this study. No differences were found between groups for treatment tolerability (3.20 + 0.87 vs. 2.16 + 0.75). Statistically significant lower PEG scores were noticeable with the TPRF group after the course (12.73 + 5.79 vs. 24.53 + 10.21, p=0.013). Their statistical significance lasted for 3 months although the difference gap diminished after 1 month. CMS scores were significantly higher in the TPRF group (70.84 + 6.74 vs. 59.56 + 9.49, p=0.007) right after treatment course but the significance did not last. Conclusions: In treating chronic shoulder tendinitis using two transcutaneous stimulation techniques, both TPRF and TENS are safe and effective. TPRF is superior to TENS.

Pulsed radiofrequency stimulation suppresses palmar hyperhidrosis in an animal study.

Objectives: Palmar hyperhidrosis (PH) exhibits excessive and unpredictable sweating. The most effective treatment for permanent cure is the ablation of thoracic sympathetic ganglia innervating hands. However, sympathectomy of T2 sympathetic ganglion by clipping or cauterization causes irreversible nerve damage, and results in a compensatory hyperhidrosis (CH). We herein used the pulsed radiofrequency (PRF) stimulation to reversibly block sympathetic ganglion to treat PH and avoid CH. Material and Methods: A bipolar electrode was implanted into the right T2 sympathetic trunk by endoscopic surgery and PRF was delivered through the electrode. The humidity (%) of right palm was measured to indicate sweating level. Results: Six out of 13 rats (46.2%) that received a 5-min PRF stimulation on the T2 sympathetic trunk showed a decrease in the right palm humidity during the surgery. PRF stimulation significantly reduced humidity from 69.17% ± 0.72% obtained from baseline condition to 66.93% ± 0.69%. The humidity reduction was also observed at 10 min after the PRF stimulation. We further evaluated the effect of PRF stimulation 1 week after surgery and found that the PRF stimuli reduced right hand humidity in 5 out of 8 rats (62.5%). PRF stimulation significantly reduced humidity from 66.11% ± 0.81% obtained from sham operation control to 63.62% ± 0.82%. The percentage of right hand humidity obtained 10 min after PRF stimulation was also reduced to 63.38% ± 0.80%. Anesthetics have no effect on humidity. Conclusions: These results indicate that PRF stimulation of T2 sympathetic trunk reduces palm sweating in rats.

A remotely-controlled locomotive IC driven by electrolytic bubbles and wireless powering.

A batteryless remotely-controlled locomotive IC utilizing electrolytic bubbles as propelling force is realized in 0.35 µm CMOS technology. Without any external components, such as magnets and on-board coils, the bare IC is wirelessly powered and controlled by a 10 MHz ASK modulated signal with RS232 control commands to execute movement in four moving directions and with two speeds. The receiving coil and electrolysis electrodes are all integrated on the locomotive chip. The experiment successfully demonstrated that the bare IC moved on the surface of an electrolyte with a speed up to 0.3 mm/s and change moving directions according to the commands. The total power consumptions of the chip are 207.4 µW and 180 µ W while the output electrolysis voltages are 2 V and 1.3 V, respectively.

A dual-mode highly efficient class-E stimulator controlled by a low-Q class-E power amplifier through duty cycle.

This paper presents the design flow of two high-efficiency class-E amplifiers for the implantable electrical stimulation system. The implantable stimulator is a high-Q class-E driver that delivers a sine-wave pulsed radiofrequency (PRF) stimulation, which was verified to have a superior efficacy in pain relief to a square wave. The proposed duty-cycle-controlled class-E PRF driver designed with a high-Q factor has two operational modes that are able to achieve 100% DC-AC conversion, and involves only one switched series inductor and an unchanged parallel capacitor. The measured output amplitude under low-voltage (LV) mode using a 22% duty cycle was 0.98 V with 91% efficiency, and under high-voltage (HV) mode using a 47% duty cycle was 2.95 V with 92% efficiency. These modes were inductively controlled by a duty-cycle detector, which can detect the duty-cycle modulated signal generated from the external complementary low-Q class-E power amplifier (PA). The design methodology of the low-Q inductive interface for a non-50% duty cycle is presented. The experimental results exhibits that the 1.5-V PA that consumes DC power of 14.21 mW was able to deliver a 2.9-V sine wave to a 500 Ω load. The optimal 60% drain efficiency of the system from the PA to the load was obtained at a 10-mm coupling distance.

In situ measurement of tissue impedance using an inductive coupling interface circuit.

In this work, a method of an inductive coupling impedance measurement (ICIM) is proposed for measuring the nerve impedance of a dorsal root ganglion (DRG) under PRF stimulation. ICIM provides a contactless interface for measuring the reflected impedance by an impedance analyzer with a low excitation voltage of 7 mV. The paper develops a calibration procedure involving a 50-Ω reference resistor to calibrate the reflected resistance for measuring resistance of the nerve in the test. A de-embedding technique to build the equivalent transformer circuit model for the ICIM circuit is also presented. A batteryless PRF stimulator with ICIM circuit demonstrated good accuracy for the acute measurement of DRG impedance both in situ and in vivo. Besides, an in vivo animal experiment was conducted to show that the effectiveness of pulsed radiofrequency (PRF) stimulation in relieving pain gradually declined as the impedance of the stimulated nerve increased. The experiment also revealed that the excitation voltage for measuring impedance below 25 mV can prevent the excitation of a nonlinear response of DRG.