Background: In several pilot studies, transcranial brain sonography findings of substantia nigra and lenticular nucleus discriminated between idiopathic Parkinson disease (PD) and atypical parkinsonian disorders.
Objective: To study the use of transcranial brain sonography in excluding the diagnosis of idiopathic PD in patients with sporadic parkinsonism.
Design and setting: All patients with parkinsonism admitted to our movement disorder clinic from January 1, 2003, through December 31, 2005, who fulfilled clinical diagnostic criteria for definite PD, probable parkinsonian variant of multiple-system atrophy (MSA-P), or probable progressive supranuclear palsy (PSP) were prospectively studied with transcranial brain sonography by an investigator blinded to clinical diagnoses. Patients Eligible patients included 138 with sporadic idiopathic PD (82 men and 56 women; mean +/- SD age, 67.1 +/- 9.8 years; mean +/- SD disease duration, 7.5 +/- 6.3 years; mean +/- SD motor score on the Unified Parkinson Disease Rating Scale, 32.6 +/- 18.1), 21 with MSA-P (10 men and 11 women; mean +/- SD age, 65.4 +/- 9.5 years; mean +/- SD duration of disease, 3.1 +/- 2.0 years; mean +/- SD motor score, 33.5 +/- 16.1), and 22 with PSP (13 men and 9 women; mean +/- SD age, 71.2 +/- 5.5 years; mean +/- SD duration of disease, 3.4 +/- 2.4 years; mean +/- SD motor score, 46.2 +/- 18.9). In 7 patients, transcranial brain sonography was not possible owing to insufficient temporal acoustic bone windows.
Main outcome measures: Sensitivity, specificity, and predictive value of transcranial brain sonography in indicating an atypical parkinsonian syndrome rather than idiopathic PD in patients with sporadic parkinsonism.
Results: Normal echogenic substantia nigra indicated MSA-P rather than PD (sensitivity, 90%; specificity, 98%; positive predictive value, 86%), whereas third-ventricle dilatation of more than 10 mm in combination with lenticular nucleus hyperechogenicity indicated PSP rather than PD (sensitivity, 84%; specificity, 98%; positive predictive value, 89%). Normal echogenic substantia nigra combined with lenticular nucleus hyperechogenicity indicated MSA-P or PSP (sensitivity, 59%; specificity, 100%; positive predictive value, 100%). In parkinsonism with age at onset younger than 60 years, normal echogenic substantia nigra alone indicated MSA-P or PSP (sensitivity, 75%; specificity, 100%; positive predictive value, 100%).
Conclusions: Distinct transcranial brain sonography findings can exclude the diagnosis of PD in patients with sporadic parkinsonism. Sonographic discrimination of atypical parkinsonian syndromes from PD is clearer in patients with onset of parkinsonism at younger than 60 years.