44-year-old (currently) M who noted a significant change in his health, primarily muscle pain and fatigue, within 3 weeks of receiving his 7th anthrax vaccine in Jul 2007. Prior to Jul 2007 vaccine receipt, patient was in his usual state of excellent health, typically running 6 miles/day and bicycling 200 miles/week. Patient had completed a 1/2 marathon earlier in 2007 and reports he was in the "best shape ever". Onset of patient's symptoms occurred shortly after he moved in Jul 2007. On his second day at his new job, he received his 7th anthrax vaccine. Within 1 month of vaccine receipt, patient could not even run 2 miles due to lower extremity pain and significant post-exercise fatigue. During the next 12 months, patient's symptoms continued and were intense. Because of lower extremity muscle and joint pain, "heaviness" in lower extremity muscles, and inability to recover following exercise, patient discontinued running for 9 months. During this period, the pain patient experienced was in the large muscles of his lower extremities, as well as in his hip and knee joints. It was dull, aching pain with pain intensity of 7/10 using a pain scale of 0 (=no pain) to 10 (=worst pain ever experienced). Pain was constant and did not migrate but affected all lower extremity large muscles and joints simultaneously. Patient had difficulty going to sleep because pain seemed worse at bedtime. He tried a variety of treatments including anti-inflammatories, moist heat, massage, compression sleeves, and topical analgesics. Nothing he tried relieved his pain. The pain improved the most when patient changed from prolonged sitting to getting up and walking, or after walking, sitting to rest. He also noted moderate benefit with compression sleeves on calves. Patient denies experiencing numbness and tingling in his lower extremities. Patient describes his concomitant fatigue as feeling of inadequate energy to perform activities and the sensation of exhaustion. At times, he struggled to stay awake. If his baseline energy level was 100%, during his first year post-symptom onset, he rates his energy level as 30-40%. He would awaken feeling unrefreshed and this feeling would continue through the day; on rare occasions the fatigue would worsen during the day. He could tell when he needed to rest and recover, but even though he would significantly reduce or stop activities, he would experience a period of increased fatigue lasting from weeks to up to several months. During this period, patient typically was able to sleep 6-7 hours/night. If he did not get at least 6 hours of sleep, he felt worse the following morning. He would take brief naps on the weekend, otherwise he did not nap.  He denies a history of associated symptoms of fevers, sore throat, swollen glands, headaches, cognitive changes, and dizziness or passing out. In 2008, patient began running again. He gradually increased his pace and distance. He "pushed through" the pain and fatigue. He would stop running when his legs became too heavy, and he would take time to recover from post-exercise malaise. He was able to continue this pattern for 3 - 6 months at a time and then would reach a point where "he knew it was doing more harm than good". At that point, he would take 2 - 4 weeks off and then gradually start over again. Patient reports his symptoms of lower extremity muscle and joint pain, lower extremity heaviness, and generalized fatigue have waxed and waned through the years since 2008. His symptoms have never completely resolved. The character of his symptoms has not changed significantly except for intensity. At his best, his lower extremity pain intensity was rated as 3-4/10 and his energy level increased to about 70% of his baseline. Patient has learned to balance his activities and rest. Patient received subsequent anthrax vaccines without exacerbation of his symptoms, and denies worsening of symptoms in temporal association to other vaccines. Denies history of large local vaccination site reactions. Denies symptoms consistent with IgE-mediated hypersensitivity reaction within first 24 hours of vaccine receipt. Since 2008, patient sought evaluation and treatment for his chronic symptoms. He had evaluations through Internal Medicine, Hematology/Oncology, Cardiology, Pulmonary, and Endocrinology. [Medical records of evaluation and testing not visible through database.] Patient was diagnosed with hypogonadism in 2010 and testosterone was prescribed; he did not experience a significant improvement of symptoms while taking testosterone; he discontinued supplemental testosterone in 2012 and had normal testosterone levels in Dec 2015. Patient was diagnosed with mild Obstructive Sleep Apnea (OSA) in 2016, with recent follow-up to adjust his CPAP settings; he has not noted a significant improvement of his symptoms. Patient is being evaluated for mild anemia with additional testing pending. Patient does not have diabetes or hypothyroidism. He denies a history of mononucleosis. He denies depression. Patient reports one of his best periods was between Sep and Nov 2015. He was able to run for 4 days with 1 day off then 1 day of running, followed by another day off. On average, he was running about 25 miles/week. This continued until Dec 2015 and then he had to stop. He restarted his gradual resumption of running in Jan 2016. He was able to pass his PT test in Mar 2016, but then had to take a week off. Last week, patient did not run for 4 days of the week, so overall, he is doing "okay", but not as well as in Fall 2015. Patient also notes improvement of his lower extremity pain since the initiation of gabapentin in Jan 2016.