Multiple system atrophy with syndrome of inappropriate antidiuretic hormone secretion: clinical analysis on three cases

Abstract

Background Multiple system atrophy (MSA) is a neurodegenerative disorder affecting motor (either extrapyramidal or cerebellar) and autonomic nervous systems. The main clinical manifestations of MSA are parkinsonism, cerebellar ataxia and autonomic dysfunction. It may also affect the hypothalamus and related fibers, resulting in syndrome of inappropriate antidiuretic hormone secretion (SIADH) and hyponatremia. This study aims to identify the clinical characteristics of MSA with SIADH, so as to provide evidence for clinical diagnosis and treatment. Methods Clinical manifestations, laboratory examinations and imaging features, diagnosis and treatment of 3 MSA patients with SIADH in our hospital from 2011 to 2015 were retrospectively analyzed. Results Among 3 MSA patients, 2 cases were parkinsonism-predominant (MSA-P) and the other one was cerebellar-predominant (MSA-C). All of them presented severe hyponatremia. The lowest serum sodium concentration was 123, 118 and 121 mmol/L, respectively. The level of urinary sodium concentration was 91, 114 and 129 mmol/L, respectively. One was diagnosed as definite SIADH, and the other 2 cases were possible SIADH. Two cases were complicated with infection (one Legionella pneumophila and one pulmonary infection), which was greatly improved after anti-infection treatment and sodium supplement. The other case died of refractory hyponatremia in the end. Conclusions MSA patients with autogenous or concurrent infection may be susceptible to SIADH, therefore water-sodium balance management is important for MSA patients. MSA with SIADH is rare, and refractory hyponatremia may indicate a poor prognosis.

DOI: 10.3969/j.issn.1672-6731.2017.02.009