The Clinical Syndrome of Paroxysmal Exercise-Induced Dystonia: Diagnostic Outcomes and an Algorithm.

Paroxysmal exercise-induced dyskinesia (PED) is characterized by recurrent episodes of involuntary movement disorders usually precipitated by sustained walking or running. Recently, mutations in the gene encoding for glucose transporter type 1 (GLUT-1) were described in a number of families with autosomal dominant PED. However, the underlying etiology of PED is quite heterogeneous. We describe a large series of patients presenting with PED. Of 16 patients, we reached a conclusive diagnosis for 11 (4 patients with GLUT-1 mutations, 4 patients with early Parkinson's disease, 2 with dopa-responsive dystonia, and one with a psychogenic/functional movement disorder). For the remaining 5 patients, the final diagnosis remained descriptive. Although certain clinical features might allow etiological distinction between cases, clinical examination alone is not always conclusive. Based on our series, we propose a diagnostic algorithm to aid the differential diagnosis of PED.