A Practical Approach to Early-Onset Parkinsonism

Abstract

Early-onset parkinsonism (EO parkinsonism), defined as subjects with disease onset before the age of 40 or 50 years, can be the main clinical presentation of a variety of conditions that are important to differentiate. Although rarer than classical late-onset Parkinson's disease (PD) and not infrequently overlapping with forms of juvenile onset PD, a correct diagnosis of the specific cause of EO parkinsonism is critical for offering appropriate counseling to patients, for family and work planning, and to select the most appropriate symptomatic or etiopathogenic treatments. Clinical features, radiological and laboratory findings are crucial for guiding the differential diagnosis. Here we summarize the most important conditions associated with primary and secondary EO parkinsonism. We also proposed a practical approach based on the current literature and expert opinion to help movement disorders specialists and neurologists navigate this complex and challenging landscape.

Keywords: Parkinsonian disorders; Parkinson’s disease; adult-onset dystonia-parkinsonism; autosomal recessive early-onset; dopa-responsive dystonia; genetic counseling; secondary Parkinson’s disease.

Fig. 1

Clinical presentation of the different forms of EO parkinsonism. Monogenic forms of EOPD and other forms of EO parkinsonism are listed on the left. For each condition the frequency of the listed clinical features (top row) is represented by the size and the color of the corresponding dot. Symptoms are described as frequent (if expected to be found in more than 75% of cases of a specific form of EO parkinsonism), present (expected to be found in 25–75% of cases), uncommon (expected to be found in < 25 of cases), or absent (never reported in the specific phenotype), based on data reported in the literature and authors’ experience. Conditions were ordered according to the frequency of parkinsonian features.