A 75-year-old hospitalized woman with a history of Alzheimer dementia is evaluated due to labile blood pressure and worsening agitation. The patient was admitted 4 days ago for right hip replacement after a traumatic fall and hip fracture. Her immediate postoperative course was complicated by agitation, and she was treated with haloperidol. Despite treatment, the patient continues to be agitated and confused. Today, her systolic blood pressure has measured between 120 and 170 mm Hg. Temperature is 38.7 C (101.6 F), pulse is 120/min, and respirations are 22/min. Pulse oximetry is 97% on room air. On mental status examination, the patient is not oriented to place or person. She is drooling and diaphoretic. Heart and lungs are normal. The abdomen is soft and nontender. The operative site is clean and dry. Muscle tone is increased in both the upper and the lower extremities. Tremor is present. Deep tendon reflexes are 2+. Babinski sign is absent. Laboratory results are as follows: Which of the following is the most likely explanation for this patient's symptoms?

Question

A 75-year-old hospitalized woman with a history of Alzheimer dementia is evaluated due to labile blood pressure and worsening agitation.  The patient was admitted 4 days ago for right hip replacement after a traumatic fall and hip fracture.  Her immediate postoperative course was complicated by agitation, and she was treated with haloperidol.  Despite treatment, the patient continues to be agitated and confused.  Today, her systolic blood pressure has measured between 120 and 170 mm Hg.  Temperature is 38.7 C (101.6 F), pulse is 120/min, and respirations are 22/min.  Pulse oximetry is 97% on room air.  On mental status examination, the patient is not oriented to place or person.  She is drooling and diaphoretic.  Heart and lungs are normal.  The abdomen is soft and nontender.  The operative site is clean and dry.  Muscle tone is increased in both the upper and the lower extremities.  Tremor is present.  Deep tendon reflexes are 2+.  Babinski sign is absent.  Laboratory results are as follows:  Which of the following is the most likely explanation for this patient's symptoms?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d78a_af99_bc81_e9e5aabe7fe2_MD0003_00 This patient initially had postoperative delirium, which is common in elderly patients with dementia, and received treatment with an antipsychotic (haloperidol). She subsequently developed muscular rigidity, altered mental status, autonomic dysregulation (eg, labile blood pressure, tachycardia, diaphoresis), and fever, findings concerning for neuroleptic malignant syndrome (NMS), an uncommon but life-threatening idiosyncratic complication of antipsychotics. Because dopamine antagonism is the mechanism of action of all first-generation and most second-generation antipsychotics, NMS is likely due to dopamine dysregulation: Central dopamine receptor blockade in the hypothalamus may cause autonomic dysregulation and hyperthermia. Dopamine antagonism in the nigrostriatal pathway may lead to tremor and diffuse lead-pipe rigidity (stiffness maintained equally through the entire range of motion). Sustained muscle contraction can lead to muscle breakdown, leading to laboratory abnormalities, including elevated creatine kinase and myoglobinuria (urinalysis positive for blood but few red blood cells). Leukocytosis with left shift is also common. (Choice A) In malignant hyperthermia (MH), exposure to certain anesthetic agents (eg, succinylcholine, inhalational gasses) causes a hypermetabolic crisis with sustained muscle contraction that leads to tachypnea, tachycardia, hyperthermia, and myoglobinuria. However, most cases arise during or shortly after induction of anesthesia and are associated with high mortality within 24 hours if untreated (eg, with dantrolene); this makes MH an unlikely explanation for this patient's symptoms persisting 4 days postoperatively. (Choice B) Excessive catecholamine-producing tumors (eg, pheochromocytomas) can cause resistant hypertension with tachycardia. Surgical removal can precipitate catecholamine surges and result in labile blood pressures, high fever, and fatal arrhythmias. However, muscle rigidity and altered mental status would not be expected. (Choice D) Although infection should be considered in this postoperative patient with fever and leukocytosis, her labile hypertension (vs hypotension more commonly seen in sepsis), increased muscle tone, and tremor make NMS more likely. In addition, her urinalysis shows no evidence of infection (negative nitrites, 1-2 white blood cells/hpf), and deep joint infections without overlying skin breakdown are unlikely in the first few postoperative days. (Choice E) Cerebellar infarctions classically present with vertigo, nystagmus, and ataxia. Although infarction can be accompanied by autonomic dysregulation if the lateral medulla is also affected, increased muscle tone, fever, and altered mental status would not be expected. Educational objective: Neuroleptic malignant syndrome (NMS) is characterized by severe muscular rigidity, mental status changes, autonomic dysregulation, and fever. Dopamine antagonism, which occurs with the use of most antipsychotics, has been implicated as a primary cause of NMS. References: Neuroleptic malignant syndrome: a review from a clinically oriented perspective. (http://www.ncbi.nlm.nih.gov/pubmed/26411967)

A 75-Year-Old Hospitalized Woman with a History of Alzheimer Dementia