In some examples, a chronic implantable neurostimulator supports trial and chronic modes of operation. In addition, in some examples, the neurostimulator can alternatively include one or more sensors that may or may not function differently in trial and chronic modes. The device may be designed to be used as both a trial neurostimulator and a permanent, or chronic, neurostimulator. A trial neurostimulation period can be used to evaluate the efficacy of the therapy. A percutaneous or implantable trial neurostimulator is used for the trial neurostimulation period. In most cases, the trial period is successful, in which case the trial stimulator is explanted and replaced with a permanent, i.e., “chronic,” implantable stimulator. In accordance with the disclosure, an implantable neurostimulator supports both trial neurostimulation and chronic neurostimulation in the event trial stimulation is successful.