A case report of syndrome of inappropriate antidiuretic hormone secretion unveiling hypothalamic involvement in multiple system atrophy

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) and central fever are rare and underrecognized manifestations of multiple system atrophy (MSA). Here, we report a 66-year-old woman who presented with a progressively evolving combination of parkinsonian features and pronounced autonomic dysfunction, fulfilling the diagnostic criteria for clinically probable MSA. Notably, she also developed two uncommon comorbidities: euvolemic hypotonic hyponatremia fulfilling the diagnostic crite