CASE CONTINUED: Fever follows haloperidol
Initial workup. Ms. G has no significant medical or psychiatric history. She has no history of seizures, head trauma, changes in mental status, recent travel, tick bites, or mosquito bites. Family history is relevant only for a maternal aunt with a history of 1 seizure. Ms. G is employed and lives with her husband and son. She is not taking other medications, herbal supplements, or vitamins and does not use tobacco, alcohol, caffeine, or illicit drugs.
On admission, she is somnolent and arousable only to painful stimuli. Temperature is 36.7°C, blood pressure 89/58 mm Hg, heart rate 73 bpm, and respirations 21/minute. She does not talk but is cooperative to physical examination, which is otherwise unremarkable.
Neurologic exam also is unremarkable, with no evidence of meningeal irritation, abnormal reflexes, or muscle tone. Serum ammonia (51 µmol/L; normal range 7 to 42 µmol/L) is slightly elevated. Liver function tests, electrolytes, blood urea nitrogen, creatinine, complete blood counts, urinalysis, urine culture, and blood cultures are unremarkable. Ethanol, salicylate, and acetaminophen levels are negative. Evaluation reveals a positive urine drug screen only for amphetamines, attributed to use of phentermine. Chest radiography and head CT are unremarkable.
Electroencephalography (EEG) 17 hours after admission reveals left anterior temporal spikes suggestive of seizure activity lasting 50 seconds. The patient is described as stuporous but arousable during EEG, and diffuse delta slow waves are superimposed on an alpha rhythm with intermittent diffuse delta bursts. Brain MRI is unremarkable.
Despite no clinical evidence of seizure, Ms. G is transferred to the cardiac telemetry ward to monitor for potential side effects from IV phenytoin loading, at which time (24 hours after admission) she is found to have intermittent sinus tachycardia ≤140 bpm.
Antipsychotic therapy. Thirty hours after admission—after phenytoin loading and normalized EEG—Ms. G shows periodic episodes of sudden startling, with repetitive leg shaking. Continuous ankle clonus is present bilaterally. She complains of severe paresthesias in her legs and is unable to urinate on her own.
NMS signs emerge. Forty-eight hours after admission, Ms. G becomes febrile (38.3°C) and shows tachycardia, with heart rate consistently >130 bpm. Her vital signs did not normalize before the fever developed. She remains somnolent and continues to have spastic lower leg and ankle clonus. She shows no seizure activity on video EEG monitoring during later episodes of repetitive leg shaking, approximately 60 hours after admission.
Ms. G receives empiric vancomycin, ceftriaxone, ampicillin, and acyclovir for possible infectious encephalitis, and lumbar puncture is done emergently. Further laboratory tests reveal creatine kinase (CK) elevation (17,282 U/L, from 270 on admission), leukocytosis (white blood cell count 16.1K/mm3, from 7.2K on admission), and elevated transaminases (AST 199 U/L, up from 21 on admission; ALT 84 U/L, up from 19 on admission).
She is transferred to the ICU with a preliminary diagnosis of NMS. Again, continuous EEG monitoring does not show seizure activity. CSF specimen is negative for infection (negative cultures, negative herpes simplex virus PCR, protein 31 mg/dl, glucose 75 mg/dl). She is started on dantrolene, bromocriptine, and levodopa but shows no initial improvement.
Intubation. On hospital day 8, the patient is intubated to protect her airway and placed in a pentobarbital coma for 2 days, with no improvement. On hospital day 9, cyproheptadine, 24 mg/d, is added for possible serotonin syndrome, and continued for 9 days.
On day 11, the addition of IV diazepam, 10 mg per hour, is followed by gradual improvement in rigidity. Ms. G remains on continuous EEG, with no evidence of seizure activity before diazepam was added or after it is tapered off by day 23.
Discharge. Ms. G is extubated on hospital day 18. On day 23 she can follow commands but is not fully oriented, and levodopa, phenytoin, bromocriptine, and dantrolene are tapered off. She is discharged to a rehabilitation facility, where she again requires phenytoin for a witnessed seizure, attributed to anticonvulsant withdrawal.
On follow-up phone interviews 4 and 18 months after hospitalization, Ms. G says she remains seizure-free without taking anticonvulsants. She reports a subjective, interval improvement in cognitive function, which has since returned to baseline.