Diagnostic value of combined assessment of olfaction and sustantia nigra hyperechogenicity for Parkinson's disease.
BACKGROUND
Hyposmia and substantia nigra hyperechogenicity (SN+) are characteristic markers of Parkinson's disease (PD), although their diagnostic value in isolation may be limited. We evaluated the combined prevalence of both disorders in patients diagnosed with PD and assessed their diagnostic yield compared to a sample with essential tremor (ET) and another group of healthy subjects.


METHODS
Patients diagnosed with PD and ET and treated in our outpatient clinic were enrolled. Olfaction was assessed using the "Sniffin' Sticks" odour identification test (SS-12) and hyperechogenicity of the substantia nigra (SN+) was assessed by transcranial duplex ultrasound.


RESULTS
A total of 98 subjects were analysed, comprising 30 with PD, 21 with ET, and 47 controls. The respective prevalence rates of hyposmia (SS-12 < 8) and SN+ (area > .24cm(2)) were 70% and 83.3% in PD, 33.3% and 9.5% in ET, and 17% and 10.6% in controls. Both markers were present in 63% of patients with PD, none of the patients with ET, and only 2 of the controls.


CONCLUSIONS
Combined use of substantia nigra sonography and olfactory testing with SS-12, two rapid, safe, and accessible tests, was more specific than each isolated marker for distinguishing patients with PD from patients with ET and control subjects. Since both markers have been described in very early phases of PD, combined use may be helpful in providing early diagnosis of PD.
Servicio de Neurología, Hospital IMED Levante, Benidorm, Alicante, España. Electronic address: lopez_nic@gva.es.
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López Hernández
Servicio de Neurología, Hospital IMED Levante, Benidorm, Alicante, España.
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García Escrivá
Servicio de Análisis Clínicos, Hospital de Torrevieja, Torrevieja, Alicante, España.
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Shalabi Benavent
D000368:Aged; D042241:Early Diagnosis; D020329:Essential Tremor / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D012372:ROC Curve; D012903:Smell / Q000502:physiology*; D013378:Substantia Nigra / Q000000981:diagnostic imaging* / Q000473:pathology; D017585:Ultrasonography, Doppler, Transcranial
Diagnostic markers; Disfunción olfatoria; Ecografía transcraneal; Enfermedad de Parkinson; Hiperecogenicidad de sustancia negra; Marcadores diagnósticos; Olfactory dysfunction; Parkinson's disease; Substantia nigra hyperechogenicity; Transcranial sonography