Substantia Nigra Echogenicity in Parkinsonian Disorders

目 的:パーキンソン病 (Parkinson disease:PD),多系統萎縮症 (multiple system atrophy:MSA),進行性核上性麻痺 (progressive supranuclear palsy:PSP) の患者において経頭蓋超音波検査 (transcranial sonography:TCS) よる中脳黒質の高輝度変化を検討した.方 法:パーキンソン関連疾患連続110 例 (PD 86 例,MSA 12 例,PSP 12 例) と健常者34 例に対しTCSを施行した.中脳黒質を観察しえたPD 47 例,MSA 10 例,PSP 6 例,健常者32 例を解析対象として中脳黒質高輝度所見を評価した.定性評価は高輝度の程度によって視察的にI:none or faint,II:equivocal,III:definite,IV:marked の4 段階に分類した.定量評価は中脳黒質で高輝度変化の面積が0.20 cm2 以上のとき,病的な黒質高輝度変化と定義した.結 果:定性評価では,高輝度範囲が視察的に病的と判定されるIII+IVの割合は,PD 72.4%,MSA 10.0%,PSP 66.7%,健常者3.1%であった.定量評価では,PD 63.8%,MSA 20.0%,PSP 66.7%,健常者9.4%で病的な高輝度変化をみとめた.PD,PSP で病的な高輝度変化の割合が多かった.PSP をPSP-parkinsonism( PSPP)とRichardson's syndrome の2 群に分けた場合,前者では病的な高輝度変化を3 例中3 例 (100%), 後者では3 例中1 例( 33.3%) に認められ,PSP-P で割合が高かった.MSA では10 例中2 例( 20%) に病的な高輝度を認め,いずれもパーキンソン病型の多系統萎縮症であった.結 論:パーキンソン関連疾患における病的な中脳黒質高輝度変化は,疾患特異性というよりも,パーキンソニズムの症候と関連し,ドパミン神経細胞の脆弱性を示す所見と推察された.
Objective:We investigated substantia nigra (SN) hyperechogenicitydetermined by transcranial sonography(TCS) to detect abnormalities, and compare findings withthose from Parkinson disease (PD), multiple system atrophy(MSA), progressive supranuclear palsy (PSP) or controlsubjects.Method:In this study, echogenicity of SN was examinedin consecutive 110 parkisonian disorders patients with PD86, MSA12, PSP 11, and 34 control subjects. A sufficientbone window for TCS was available in 47 of 86( 71.2%) inthe PD group, 10 of 12( 86.3 %) in the MSA group, 6 of 11(54.5%) in the PSP group and 32 of 34( 94.1%) in the controlgroup. SN hyperechogenicity was scored using a fourpointscale as follows:I=none or faint, II=equivocal, III=definite, IV=marked. In accordance with previously reportedcut-off values, areas of echogenicity £ 0.19 cm2 wereclassified as normal and areas of echogenicity £ 0.20 cm2were classified as pathological SN hyperechogenicity.Results:The frequency of SN hyperechogenicity, assessedas III and IV scales, was significantly increased in PDpatients, and observed in 72 . 4 % of assessable SN(34/47);qui-squire;p=0.001, vs. controls). The meansize of the SN hyperechogenic area in the PD group, MSAgroup and PSP group was 0.26 cm2±0.13, 0.11 cm2±0.11and 0.23 cm2±0.04, respectively, compared with 0.07 cm2±0.06 in the control group.We have identified two clinical phenotypes, such as Richardson'ssyndrome (RS) and PSP-parkinsonism (PSP-P).All of three PSP-P (100%) patients showed a pathologicalSN hyperechogenicity.Conclusion:SN hyperechogenicity was associated with asymptom of parkinsonism rather than disease specificity,and suggested a vulnerability marker of the dopaminergicneuron.