Question: One of our technicians is training to perform repetitive nerve stimulation on patients with myasthenia gravis. How should I code this? North Carolina Subscriber Answer: The correct code is 95937 (Neuromuscular junction testing [repetitive stimulation, paired stimuli], each nerve, any one method). The primary diagnosis for myasthenia gravis is 358.0x (Myasthenia gravis). When you report the patient's diagnosis, include the fifth digit to clarify whether the patient has acute exacerbation: 358.00 (Myasthenia gravis without [acute] exacerbation) or 358.01 (Myasthenia gravis with [acute] exacerbation).