How long after an EMG can one have a muscle biopsy done on that muscle. And can any medications affect the results of an EMG or biopsy. I am currently on Soma Cmpd 350 mg 3x, Flexeril 10 mg 3x, Baclofen 20 mg 4x, Valium 5mg 2x, Amitriptyline 25 mg 1x. And still with no relief.