Acute agitation and rigidity after total knee arthroplasty
On postoperative day 2 following an elective left total knee arthroplasty, a 67-year-old retired botanical garden docent develops acute agitation, profuse diaphoresis, and confusion. Her daughter notes the patient's arms are rigidly clenched. Review of the inpatient record shows her home carbidopa-levodopa was held preoperatively and omitted from post-procedure orders. Temperature is 39.1 C (102.4 F), pulse 116/min, blood pressure 158/92 mm Hg, and respirations 24/min. Examination shows generalized lead-pipe rigidity, mutism, and diaphoresis, without focal surgical-site erythema or clonus. Leukocyte count is 13,800/mm3 and serum creatine kinase is 4,120 U/L. Which of the following is the most appropriate next step in management?
See the answer and explanation below:
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B
Explanation
Clinical Pearl:
Abrupt cessation or omission of dopaminergic medications can precipitate neuroleptic malignant-like syndrome, characterized by hyperpyrexia, autonomic instability, generalized rigidity, and elevated creatine kinase. Immediate reinstitution of dopaminergic therapy, enterally if swallowing is compromised, is the definitive treatment.
Explanation:
This patient has acute dopamine withdrawal syndrome (neuroleptic malignant-like syndrome), a life-threatening complication resulting from the abrupt cessation of dopaminergic therapy during perioperative care. Management requires immediate reinstitution of dopaminergic therapy, which must be administered through a nasogastric or enteral tube when encephalopathy and severe rigidity impair safe swallowing. Intravenous dantrolene is indicated for malignant hyperthermia, an anesthetic crisis that arises intraoperatively during exposure to triggering volatile gases or succinylcholine rather than days later. Broad-spectrum intravenous antibiotics are appropriate for postoperative sepsis, but infection alone fails to explain generalized lead-pipe rigidity and extreme creatine kinase elevation in a patient with a clean surgical site and documented levodopa omission. Cyproheptadine is an antidote for serotonin syndrome, an entity distinguished by tremor, hyperreflexia, and clonus rather than lead-pipe rigidity and dopamine withdrawal. Intravenous haloperidol is strictly contraindicated, as its potent dopamine receptor antagonism exacerbates central dopamine depletion and substantially worsens this withdrawal syndrome.
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