苯丙酮尿症患儿治疗前后脑白质病变的观察

Brain white matter lesions of children with phenylketonuria before and after treatment

摘要:

目的：该研究应用MRI观察晚治苯丙酮尿症(PKU)患者治疗前后脑白质病变。方法：确诊为经典型PKU患者19例,进行低苯丙氨酸(PHE)饮食治疗随诊8～16月，治疗前后分别进行了头颅MRI及智商检查。头颅MRI采用常规矢状面、轴面T1W和轴面T2W扫描，对脑白质T2高信号病变按Thompson6级分级法进行分级并评分。观察比较治疗前后脑白质病变的改变。结果：9例晚治PKU患者头颅MRI均存在脑白质病变，其病变主要表现为侧脑室周围及三角区白质等区域存在孤立性斑片状异常T2高信号，治疗前后的平均MRI脑白质T2高信号分级分别为2.59和1.76，治疗前后MRI分级按分数计算，差异有显著性(P<0.01)，治疗后T2高信号等级改善。19例均存在不同程度的智力发育落后，在智商改善与T2高信号等级改善可见部分一致关系。血PHE浓度与脑白质病变间有关。结论：晚治PKU患者脑白质病变及智力发育落后具高发生率，低苯丙氨酸饮食治疗降低血苯丙氨酸浓度后脑白质病变及智商均有部分改善，提示PKU患者脑白质病变及智力损害是部分可逆的，PKU患者脑白质改变可能是导致晚治PKU患者智能发育障碍的原因之一。

Abstract:

OBJECTIVE: To observe brain white matter changes in children with late-treated phenylketonuria (PKU) before and after receiving treatment. METHODS: This study included 19 PKU patients(aged 34-410 weeks) who were administered a low-phenylalanine diet (<15-50 mg/kg daily) for 8-16 months. The brain MR imaging with spin-echo T1-weighted and T2-weighted sequences in coronal and axial planes was taken before and after treatment. The white matter abnormalities (T2WI high signal intensity) were graded based on the Thompson grading system. Meanwhile the intelligence quotient (IQ) or developmental quotient (DQ) was tested by the Gesell's Intelligence Scale. RESULTS: All 19 PKU patients presented with the brain white matter lesions, manifesting abnormally high T2-signal intensity in the periventricular region around anterior and posterior horns of both lateral ventricles. Different extents of mental retardation were also observed in the 19 patients. The low-phenylalanine diet treatment decreased the average grade of abnormal T2-signal intensity from 2.59 to 1.76 (P<0.05). The mean IQ or DQ improved from 44.8 to 61.6 after treatment (P<0.05). There was some correlation between the amelioration of brain white matter lesions and IQ or DQ. CONCLUSIONS: The patients with late-treated PKU have a higher occurrence of the brain white matter lesions and mental retardation. A low-phenylalanine diet treatment can partly improve the abnormalities. Brain white matter lesions may play a part in mental retardation.