with a frequency in the 50-100 pps range, with short pulse and phase durations of 2-50 μs, and low intensities. Short pulses must be used to avoid producing tetanic muscular contractions - muscular movement is not desirable in sensory-level TENS. Amplitude is adjusted to achieve superficial cutaneous nerve fiber activation. The patient should perceive paresthesia beneath the electrodes and amplitude is adjusted according to patient feedback. The mechanism of action for this level of electroanalgesia is likely either the direct peripheral block of nerve transmission or the activation of central inhibition mechanisms of pain transmission by large-diameter fiber stimulation. Sensory-level stimulation is the most researched level of electroanalgesia and is usually perceived by the patient as very comfortable. There should be an immediate decreased response to pain and treatment times last 20–30 minutes. Motor-level stimulation Response to motor-level stimulation is often not immediately but its effect is long-lasting. Due to the lack of immediate effect, treatment times are typically longer and are conducted for 45 minutes or longer. The mechanism of action may be attributed to the production of rhythmic motor contractions that activate the endogenous opiate mechanisms of analgesia. This level of electroanalgesia is most often used in patients with deep, throbbing, or chronic pain. Noxious-level stimulation By utilizing low frequency (1-5 pps) or high frequency (80-100 pps) stimuli with durations of up to 1 second and amplitudes that produce pain, noxious-level stimulation seeks to ameliorate pain through the induction of a painful stimulus either at the pain site or at a remote location. The mechanism of action is believed to be related to an endorphin-mediated mechanism accompanied by the release of endogenous opiates that increase the patient's pain threshold. This level of stimulation is not the first approach chosen for electroanalgesia due to its induction of pain. Other uses of Clinical Electrophysiology Muscle for Control of Movement and Posture Biofeedback for Genitourinary Dysfunction Electromyographic Biofeedback for Improvement of Voluntary Motor Control Peripheral Neuroanatomy of the Upper and Lower Extremities See also Clinical cardiac electrophysiology Electroanalgesia References Electrophysiology