Levodopa should be restarted in this patient. Sudden withdrawal from dopaminergic medications, as may occur during hospitalization in patients with Parkinson disease, can lead to an acute dopamine agonist withdrawal syndrome, termed parkinsonian-hyperpyrexia syndrome, which resembles neuroleptic malignant syndrome (NMS). Patients who abruptly stop taking dopaminergic medications can develop acute altered mental status, hyperthermia, rhabdomyolysis, and extrapyramidal symptoms, including severe rigidity and dystonia. A high index of suspicion for parkinsonian-hyperpyrexia syndrome is required in these patients because mortality rates of up to 4% have been reported and may be prevented by early recognition and treatment. The differential diagnosis also includes central nervous system infection and status epilepticus. Aggressive supportive care, which may include intensive care and respiratory support, is appropriate. The primary medical therapy is restoration of dopaminergic medication.

Administration of the skeletal muscle relaxant baclofen may be helpful in patients with severe spasticity or progressive encephalomyelitis with rigidity and myoclonus, but not in those with Parkinson disease or disorders due to withdrawal from dopaminergic medications.

Dantrolene is a skeletal muscle relaxant that has proven efficacy in treating malignant hyperthermia and NMS. However, its effectiveness in parkinsonian-hyperpyrexia syndrome has not been established.

The clinical manifestations of serotonin syndrome may overlap with those of parkinsonian-hyperpyrexia syndrome and NMS, although serotonin syndrome is more often associated with hyperreflexia and myoclonus and not extrapyramidal symptoms. It typically occurs in patients taking high doses of serotoninergic agents (such as citalopram) and would not be expected in this patient in whom this medication has been withheld. Restarting the citalopram would not address the underlying disease process in this patient.