A. Numao 1, K. Suzuki 1, H. Takekawa 2, M. Miyamoto 1, T. Miyamoto 3, M. Iwanami 3, E. Takada 4, K. Hirata 1
1 Department of Neurology, Dokkyo Medical University – Tochigi, Japan
2 Stroke Division, Department of Neurology, Dokkyo Medical University – Tochigi, Japan
3 Department of Neurology, Dokkyo Medical University Koshigaya Hospital – Saitama, Japan
4 Center of Medical Ultrasonics, Dokkyo Medical University – Tochigi, Japan
Objective: In Parkinson's disease (PD), transcranial sonography (TCS) has been used to evaluate substantia nigra (SN) hyperechogenicity as a diagnostic tool. To quantify SN hyperechogenicity in patients with PD and Parkinsonian syndrome (PS), we applied semi-quantified evaluation method.
Material and Methods: Hospitalized patients with PD (n=28) and patients with PS (n=17) and in-hospital controls (n=10) were included. The PS group consisted of patients with progressive supranuclear palsy (n=7) and multiple system atrophy (n=10). TCS was performed using a conventional transcranial Doppler sonography equipped with 2.5 MHz transducer. The SN was identified within midbrain, and then the area of echogenic signals was encircled and measured according to Berg et al. Next, echogenic signal of SN and dorsal midbrain were converted into grayscale using Adobe Photoshop and a median value of SN and dorsal midbrain on histogram was obtained. The SN to dorsal midbrain ratio was calculated.
Results: The PD group (4.1±3.7) showed increased SN to dorsal midbrain ratio compared with that in PS group (1.7±0.9) and controls (1.8±1.1). The area of SN hyperechogenicity was larger in PD group (0.19±0.11 cm2) than in PS group (0.07±0.07 cm2) and controls (0.05±0.07 cm2). Both measurement of the SN hyperechogenic area and semi-quantified evaluation of SN echogenicity using SN to dorsal midbrain ratio showed good discrimination of PD from PS.
Discussion: Semi-quantified evaluation of SN echogenicity using SN to dorsal midbrain ratio is comparative to the previously reported method by Berg et al, measurement of the SN hyperechogenic area, and it may be useful in differential diagnosis of PD from PS.
Key words: Parkinson's disease, Parkinsonian syndrome, substantia nigra, transcranial sonography.