Acute Presentation of Nonmotor Symptoms in Parkinson's Disease.

There are a few syndromes involving the nonmotor symptoms of Parkinson's disease and other movement disorders that can quickly lead to severe morbidity and mortality, and, as such, need rapid identification and management. Among these are neuroleptic malignant syndrome, serotonin syndrome, dopamine agonist withdrawal syndrome, and dystonic storm. It is important to maintain a high index of suspicion for these disorders as lack of identification can lead to death. Many of these acutely occurring nonmotor syndromes are primarily the result of imbalances in dopaminergic and serotonergic systems due to changes in pharmacologic management of psychiatric disorders or Parkinson's disease. We discuss these acutely occurring nonmotor symptoms in order to raise awareness and also to highlight how these extremes in symptoms may uniquely shed light on the pathophysiology of Parkinson's disease.