title: Ultrasonographic (TCS) and clinical findings in overlapping phenotype of essential tremor and Parkinson's disease (ET-PD).
abstract: BACKGROUND
  Essential tremor (ET) and Parkinson's disease (PD) are considered distinct disorders. The aim of the study was to look for a link or any distinguishing features by transcranial sonography (TCS), together with the clinical examination findings in a group of patients with overlapping phenotype of ET and PD (ET-PD).
  
  
  METHODS
  A prospective observational case-control study was carried out from the 3rd January 2011 until 30th January 2013 at the Hospital of Lithuanian University of Health Sciences. The final study group consisted of 15 patients with ET-PD, 116 patients with ET-only and 141 patients with PD-only. The control group included 101 subjects. Clinical diagnosis was of a diagnostic standard.
  
  
  RESULTS
  The main ultrasonographic findings in the ET-PD group were similar to those of the PD-only: hyperechogenicity of the substantia nigra (66.7%, p < 0.001) and nuclei raphe interruptions/absence (38.5%, p < 0.001). The single distinguishing TCS finding in ET-PD group was a lentiform nucleus hyperechogenicity (26.7%), however this was only significant when compared to controls (p = 0.006). An asymmetrical onset of symptoms (73.3%) in ET-PD group was characteristic to PD-only. The ET-PD patients had the longest disease duration (median 6 years, p < 0.001), the most frequent rate of positive family history (53.3%, p = 0.005), rather low prevalence of cogwheel rigidity (26.7%, p < 0.001), and higher mean Hoehn & Yahr scores compared to PD-only (2.6 ± 0.8 vs. 1.8 ± 0.8, p = 0.012).
  
  
  CONCLUSIONS
  The main TCS findings of the present study in patients with overlapping ET-PD phenotype were similar to the PD-only group. The highest positive family history rate among ET-PD patients indicates a strong hereditary predisposition and needs genetic underpinnings. Some ET patients, who look like they may be developing co-morbid PD clinically, may have an alternative diagnosis for Parkinsonism, which could be delineated by TCS examination.
authors.affiliation: Department of Neurology, Lithuanian University of Health Sciences, Academy of Medicine, Mickevičiaus street 9, Kaunas LT-44307, Lithuania. kristina.lauckaite@lsmuni.lt.
authors.forename: Kristina
authors.initials: K
authors.lastname: Laučkaitė
authors.forename: Daiva
authors.initials: D
authors.lastname: Rastenytė
authors.forename: Danguolė
authors.initials: D
authors.lastname: Šurkienė
authors.forename: Birutė
authors.initials: B
authors.lastname: Vaidelytė
authors.forename: Gabrielė
authors.initials: G
authors.lastname: Dambrauskaitė
authors.forename: Andrius
authors.initials: A
authors.lastname: Sakalauskas
authors.forename: Antanas
authors.initials: A
authors.lastname: Vaitkus
authors.forename: Rymantė
authors.initials: R
authors.lastname: Gleiznienė
mesh_terms: D000368:Aged; D001921:Brain / Q000473:pathology*; D016022:Case-Control Studies; D020329:Essential Tremor / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging*; D010641:Phenotype; D017585:Ultrasonography, Doppler, Transcranial