An N-of-1 trial as an aid to decision-making prior to implanting a permanent spinal cord stimulator

Objective. Limited evidence supports the efficacy of spinal cord stimulation (SCS). Therefore, it is crucial to assess the usefulness of this invasive procedure before implanting permanent electrodes in each patient. An N-of-1 trial is an experiment in which a single participant undergoes periods of comparative treatments. We illustrate how an N-of-1 trial design may permit clinicians to conduct such an assessment in an individual patient. Design. Case report. Setting. University teaching hospital. Patients. A 61-year-old man patient with refractory postherpetic neuralgia scheduled for SCS implantation. Interventions. Percutaneous octapolar lead placement into the epidural space for SCS at T5-T6, and placement of transcutaneous electrical nerve stimulator (TENS) electrodes upon the painful area on the patient's back. We provided electrical stimulation via TENS or SCS according to a computer-generated random number list. Each stimulation period lasted 5 hours, followed by 1 hour of rest. Outcome Measures. At the end of each period, a blinded assessor evaluated the degree of pain relief, pain intensity, area of stimulation, and the patient's satisfaction. The study had a 5-day duration. Results. In this patient, spinal stimulation was equally efficacious as TENS. Conclusions. We encourage clinicians to perform an N-of-1 trial in every patient before implanting permanent electrodes for SCS.