Not all patients are suitable for regional anesthesia. Absolute contraindications to regional anesthesia include lack of patient consent, skin infection at the site of needle insertion, or when nerve blockade would hinder the proposed surgery or desired postoperative neurologic exam. Relative contraindications include coagulopathy, neuropathy, systemic infection, excessive patient anxiety, mental illness, and anatomic distortion. Neuromuscular diseases such as multiple sclerosis, polio, and muscular dystrophy may be aggravated by peripheral nerve blockade.