治疗延迟的苯丙酮尿症患儿脑髓鞘发育延迟与智力发育的研究

目的　应用磁共振成像(MRI)观察苯丙酮尿症(PKU)治疗延迟患儿治疗前后脑髓鞘发育延迟与智商的关系。方法　2 0 0 2～2 0 0 3年中日友好医院确诊经典型治疗延迟PKU患儿1 7例,治疗前后分别进行头颅MRI及智商检查,脑髓鞘发育按Staudt标准对不同年龄阶段患儿1 0个脑区域进行量化评估。智商检测采用Gesell发育量表测定。结果　治疗前所有病例存在脑髓鞘发育延迟,在1 0个脑区域脑髓鞘发育延迟平均发生率为44 . 7% ,主要部位在脑叶和胼胝体,并存在不同程度的智力发育落后,平均智商为44 .2 ;经低苯丙氨酸饮食治疗1年后,1 0个脑区域髓鞘发育延迟平均发生率为3 0 . 6% ,平均智商为60 . 6;治疗前、后脑髓鞘延迟改善有显著性(P <0. 0 1 ) ,平均智商改善有统计学意义(P <0. 0 5) ,且智商改善率与髓鞘延迟改善率间可见部分相关性。结论　治疗延迟的PKU患儿的脑髓鞘发育延迟及智力发育落后发生率较高,经低苯丙氨酸饮食治疗可使其在一定程度有所改善,但不能达到完全正常,提示脑髓鞘发育延迟可能是导致PKU患儿智力发育落后的原因之一。

Study on mental retardation and brain delayed myelination of patients with phenylketonuria

Objective To observe delayed myelination in delayed treated Phenylketonuria (PKU) with MRI and changes of IQ before and after treatment.Methods 17 PKU patients were studied. MRI of brain was repeated in 17 patients before and after 12 months, treatment; at the same time IQ was tested for evaluation of mental retardation. All underwent cranial MR imaging with spin-echo T 1 -weighted and T 2 -weighted sequences in coronal and axial planes. The myelination in ten sections was evaluated by using MRI T 1 and T 2 WI with Staudt's staging system which was originally developed to evaluate brain myelination in healthy children at different age stages. IQ was tested according to Gesell's Intelligence Scale. Comparing the changes of brain delayd myelination and mental retardation before and after treatment. Results Before treatment all of the 17 patients with PKU had aniso degree mental retardation and delayed brain myelination on MRI. The incidence of 10 sections of delayed myelination was 44.7%. Delayed myelination was located mainly in the cerebral lobes and corpus callosum; the mean IQ was 44.2.After they were treated with a PHE-restricted diet for a year, the incidence of 10 sections of delayed myelination was 30.6% ,and the mean IQ was 60.6. Delayed myelination showed statistically significant change (P<0.01) and the mean IQ showed statistically significant change before and after treatment (P<0.05). There was a part of coincidence on the curves of amelioration of the delayed myelination and IQ. Conclusion The patients with delayed treated PKU have a high occurrence of delayed brain myelination and mental retardation. Through the therapy with a PHE-restricted diet these abnormalities can be improved,but cann't be cured completely.The delayed myelination may be one of the main reasons responsible for mental retardation .