If the fall from a horse were an effect, a cerebral vascular disturbance, such as stroke, must have happened before the accident, and if a fall from a horse was the cause, it would have resulted in traumatic intracerebral hemorrhage.
落馬は結果であるなら脳卒中など脳血管障害が事故の前に起きており、落馬自体が原因なら頭部外傷性の脳内出血を引き起こしたと考えられる。