title: Transcranial sonography (TCS) in Parkinson's disease (PD) and essential tremor (ET) in relation with putative premotor symptoms of PD.
abstract: BACKGROUND
  Hyperechogenicity of substantia nigra (SN+) is a common finding in transcranial ultrasound studies of parkinsonian patients. However, this feature is also found in 13-16% of ET patients. The possible links between ET and PD are of special interest, particularly with the familial aggregated data supporting this association. However, few studies have been conducted regarding the factors associated with the emergence of PD in the ET population. In this study, we investigated the possible association between SN+ and putative premotor symptoms of PD in patients with ET.
  
  
  METHODS
  A total of 47 patients with PD and 64 patients with ET were enrolled in the study. All patients underwent TCS and completed a structured interview for putative premotor symptoms of PD.
  
  
  RESULTS
  As expected, there were significant differences observed in the frequency and size of SN+, and the prevalence of the putative premotor symptoms of PD. More interestingly, in the ET group a significant association between SN+ and each premotor symptom was observed and a trend was also found that ET cases with more putative premotor symptoms of PD had a greater size of SN+. In contrast, in the PD group, SN+ was not influenced by the cumulative effect of premotor symptoms.
  
  
  CONCLUSIONS
  The results of this study suggest that SN+ in patients with ET is influenced by the putative premotor symptoms of PD.
authors.affiliation: Department of Neurology, College of Medicine, The Catholic University of Korea, Seoul St. Mary's Hospital, 505, Banpo-dong, Seocho-gu, Seoul 137-701, Republic of Korea. neuronet@catholic.ac.kr
authors.forename: Joong-Seok
authors.initials: JS
authors.lastname: Kim
authors.forename: Yoon-Sang
authors.initials: YS
authors.lastname: Oh
authors.forename: Yeong-In
authors.initials: YI
authors.lastname: Kim
authors.forename: Ja-Seong
authors.initials: JS
authors.lastname: Koo
authors.forename: Dong-Won
authors.initials: DW
authors.lastname: Yang
authors.forename: Kwang-Soo
authors.initials: KS
authors.lastname: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D020329:Essential Tremor / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging*; D013378:Substantia Nigra / Q000000981:diagnostic imaging; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*