Study limitations include small sample size precluding subtyping by anatomical abnormalities and possible confounding by stimulant drugs, which were used by 15 of the 27 patients.

• 研究限制包括了由解剖学上异常排除非典型所造成的样本数少及兴奋剂类药物的可能干扰，研究中27位病患有15位使用。