Extensive animal studies indicate that a form of low current transcranial electrostimulation treatment (TCET) stimulates endogenous opioid and serotonergic activity, thereby inducing behavioral analgesia. Following these results, a pilot double blind placebo controlled clinical study conducted at the Montreal Neurological Hospital determined that TCET may be of benefit to patients suffering from chronic pain of central origin. The same study indicates that other forms of chronic pain (i.e., pain of peripheral origin) are not likely to benefit from TCET. The clinical goal of this project is to determine whether TCET is of benefit to patients suffering from chronic pain of central origin. Patients enrolled in the Outpatient Pain Program at the Houston Rehabilitation Institute who suffer from pain of central origin will be recruited into the study. Additional subjects will be recruited as required through local area resources such as support groups. This is a small-scale, pilot status project which is intended to form the basis for a future large scale study. Therefore, depending on recruitment rates, it is anticipated that a maximum of 24 subjects will be enrolled. Subjects will act as their own controls, receiving under blind conditions either 2 weeks of treatment followed by 2 weeks of placebo, or 2 weeks of placebo followed by 2 weeks of treatment. Experimental sessions will be held once per day, five times per week for 4 weeks (the normal duration of the HRI Outpatient Pain Program.) The McGill short form Pain Rating Scale will be administered before and after every TCET treatment session. This scale includes a Visual Analog pain scale, and will provide a subjective measure of TCET efficacy. Changes in autonomic measures including skin temperature, skin conductance, and frontalis muscle EMG are known to be influenced by the state of a patient suffering from chronic pain. These measures will be recorded every 15 minutes during each session, and will be used to objectively assess TCET efficacy. Since chronic pain sufferers are known to also suffer mood disturbances, a mood state questionnaire (the POMS instrument) will be administered at the beginning, mid-point, and end of the 4 week program. Other measures of efficacy will include retention in the study, nursing staff evaluations of patient status, and changes in use of analgesic medications.
