Distinguishing Parkinson's disease and essential tremor with transcranial sonography.
OBJECTIVE
Until today there is no reliable test that can clearly distinguish Parkinson's disease (PD) from the essential tremor (ET). Our aim was to determine the usefulness of the transcranial sonography (TCS) in the differential diagnosis of the PD and ET as well as the interobserver reliability for this method.


METHODS
Transcranial sonography of substantia nigra and clinical examination were performed on 80 PD patients, 30 ET patients, and 80 matched controls by two independent physicians.


RESULTS
Bilateral SN hyperechogenicity over the margin of 0.20 cm(2) was found in 91% of PD patients, 10% of healthy subjects, and in 13% patients with ET. Interobserver agreement for this method was significant (Student's t-test, P = 1.000).


CONCLUSIONS
Substantia nigra hyperechogenicity on TCS is a highly specific finding of PD, where in healthy individuals or in ET patients, it might correspond to an increased risk of developing PD later in life or might also be because of the impairment of nearby area of nucleus ruber in ET patients, as suggested by positron emission tomography studies. TCS may serve as a practical and sufficiently sensitive neuroimaging tool in PD diagnoses and in distinguishing it from ET; its repeatability and accuracy might add to its practical value.
Budisic
M
M
University Department of Neurology, Sestre Milosrdnice University Hospital, Zagreb, Croatia. mislavbudisic@yahoo.co.uk
Trkanjec
Z
Z
Bosnjak
J
J
Lovrencic-Huzjan
A
A
Vukovic
V
V
Demarin
V
V
D017668:Age of Onset; D000368:Aged; D003937:Diagnosis, Differential; D020329:Essential Tremor / Q000000981:diagnostic imaging*; D007839:Functional Laterality; D006801:Humans; D008875:Middle Aged; D010300:Parkinson Disease / Q000000981:diagnostic imaging*; D012016:Reference Values; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods*