A bipolar stimulator probe suitable for application of intramuscular stimulation provides an active stimulator electrode and a reference electrode as part of a single tool. The separation between the electrodes is significantly greater than the electrode separation of known bipolar stimulator probes and bipolar bar electrode configurations. The probe tool may be configured to permit adjustment of the fixed relative position of the electrodes within a given range. By providing a relatively wide spacing between the two electrodes, the tool can be used to approximate the effect of monopolar stimulation with a separate reference electrode, with the electrical stimulus producing less pain to the patient compared to bipolar stimulation where the two electrodes are spaced apart by only 2-4 cm or less.