My father had 2 accidents (falls) towards the beginning of the onslaught of symptoms which were later identified as ALS. When I look back, I see that it is difficult to tell if these accidents were caused by early ALS, which can cause imbalance and uncoordination, or perhaps were the triggers for the start of ALS. Which came first, the chicken or the egg? The first time he fell, he landed on his shoulder while carrying some heavy boxes. Strangely, his legs were also affected, and he had difficulty walking. I didn't understand how a shoulder injury could cause such weakness in the legs. He went to physical therapy and began a regimen of exercises which resulted in eventual improvement, such that he was walking well after several months. Since ALS is not known to improve, I have no idea if this incident was related to his diagnosis 4 years later or simply coincidental. The second accident happened about a year and a half after the first. Dad tripped and hit his head on a brick wall (also carrying boxes for his store). A few months after that, his backbone seemed to keel over on itself, he could not hold up his head, and his hips were swayed such that he was walking very unsteadily. He was told he had osteoporosis, though a bone density test only showed some loss of bone mass. To me, it appeared the problem had been caused by the head injury, since it happened so soon after it. However, it may be that ALS was the real cause of both the accident and the back problem. As his back muscles were atrophying, they could no longer support the structure of his neck and backbone. The confirmation of his ALS diagnosis came just 2 months before he died.