title: Gaba and serotonin molecular neuroimaging in essential tremor: a clinical correlation study.
abstract: BACKGROUND
  Essential tremor is the most common movement disorder in adults, but its exact etiology and pathophysiology are still not fully understood. There is some consensus, however, about the involvement of the cerebellum and accumulating evidence points towards a dysfunction of the gabaergic system. We hypothesize that the serotonin neurotransmission system may also play a role as it does in tremor in Parkinson disease. This study aimed to investigate the association between the severity of tremor symptoms and the gabaergic and serotoninergic neurotransmission systems in essential tremor.
  
  
  METHODS
  We measured the tremor clinical rating scale score and acquired DASB and Flumazenil PET scans in 10 patients who presented with essential tremor at different stages of clinical severity. Statistically significant correlations were sought between the scale scores and parametric binding potential images.
  
  
  RESULTS
  The correlation analysis of cerebellar Flumazenil uptake and tremor clinical rating scale scores reached statistical significance (R2 = 0.423, p = 0.041), whereas no association was detected in the DASB scans.
  
  
  CONCLUSIONS
  The severity of tremor correlated with the abnormalities found in GABA receptor binding, suggesting a primary gabaergic deficiency or a functional abnormality at the level of GABA(A) receptor subtypes. These results may assist in the rational development of new pharmacological treatments for essential tremor.
authors.affiliation: Movement Disorders Unit, Department of Neurology, Sant Pau Hospital, Autonomous University of Barcelona, Catalonia, Spain. agironell@santpau.cat
authors.forename: A
authors.initials: A
authors.lastname: Gironell
authors.forename: F P
authors.initials: FP
authors.lastname: Figueiras
authors.forename: J
authors.initials: J
authors.lastname: Pagonabarraga
authors.forename: J R
authors.initials: JR
authors.lastname: Herance
authors.forename: B
authors.initials: B
authors.lastname: Pascual-Sedano
authors.forename: C
authors.initials: C
authors.lastname: Trampal
authors.forename: J D
authors.initials: JD
authors.lastname: Gispert
mesh_terms: D000368:Aged; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D020329:Essential Tremor / Q000175:diagnosis / Q000378:metabolism* / Q000503:physiopathology*; D005260:Female; D005442:Flumazenil; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D059906:Neuroimaging / Q000379:methods*; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D049268:Positron-Emission Tomography / Q000379:methods; D011859:Radiography; D012701:Serotonin / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D012701:Serotonin; D005442:Flumazenil; D005680:gamma-Aminobutyric Acid