RESUMEN
OBJECTIVES: A pre-possible multiple system atrophy (MSA) phase, that is, the period between symptom onset and satisfying the second consensus diagnostic criteria for possible or probable MSA, may exist. The aim of the study was to identify the pre-possible MSA phase and to pursue the earlier diagnosis of MSA. MATERIALS & METHODS: We reviewed 52 patients with a clinical diagnosis of MSA and 430 patients showing any signs of parkinsonism, sporadic cerebellar ataxia, or autonomic failure with other clinical diagnoses. RESULTS: The pre-possible MSA phase was noted in 35 patients with a clinical diagnosis of MSA and 13 patients with other clinical diagnoses. During this phase, 16 patients presented with autonomic features first, while they presented later in 32 patients. Between these patients, there was no significant difference regarding parkinsonian, cerebellar features, levodopa response, or Babinski sign with hyperreflexia. Comparisons by autonomic features or autonomic function tests could not be performed due to the small number of patients. "Atrophy on magnetic resonance imaging of the putamen, middle cerebellar peduncle, pons, or cerebellum" and "new or increased snoring" showed high positive predictive values for MSA. CONCLUSION: A pre-possible MSA phase exists. Improved earlier diagnosis of MSA depends on the sensitivity and positive predictive value of autonomic features or autonomic function tests and on the sensitivity of "atrophy on magnetic resonance imaging of the putamen, middle cerebellar peduncle, pons, or cerebellum" and "new or increased snoring" during the pre-possible MSA phase.