Objectives: The differential diagnosis of patients with idiopathic parkinsonism is difficult, especially early in the course of the disease. External anal sphincter electromyography (EAS-EMG) has been reported to be of value in the differential diagnosis between Parkinson's disease (PD) and multiple system atrophy (MSA). Patients with MSA are reported to have pathological EAS-EMG and patients with PD are reported to have significantly less pathological EAS-EMG results. Comparisons between patients with parkinsonian disorders have usually been made many years into the disease, and thus it is largely unknown if the results of EAS-EMG can be used to distinguish the different diagnoses in the early phase of the disease.
Materials and methods: We investigated 148 newly diagnosed patients with idiopathic parkinsonism from a population-based incidence cohort (100 definite PD, 21 probable PD, 16 MSA, 11 progressive supranuclear palsy, and 40 controls) with EAS-EMG within 3 months of their first visit and, in the majority of patients, before start of treatment with dopaminergic drugs. The clinical diagnoses were made using established clinical diagnostic criteria after a median follow-up of 3 years.
Results: All patient groups had more pathological EAS-EMG results than controls. No EAS-EMG differences were found between the patient groups, especially not between PD and MSA.
Conclusions: External anal sphincter electromyography examination cannot separate the different parkinsonian subgroups from each other in early course of the diseases.
© 2012 John Wiley & Sons A/S.