Eosinophilic Pleural Effusion Due to Dantrolene: Resolution With Steroid Therapy

South Med J. 2001;94(5) 

In This Article

Case Report

A 22-year-old quadriplegic man had 7 days of increasing cough, dyspnea, and orthopnea. He had received dantrolene (400 mg daily) for 5 years for spasticity after traumatic C5-6 spinal injury. On examination, he was afebrile and mildly dyspneic with diminished breath sounds, egophony, and dullness to percussion to the midscapula on the right side of the thorax. Oxygen saturation was 89% on room air. Arterial blood gas measurements revealed the following values: pH 7.41, PCO2 34 mm Hg, and PO2 61 mm Hg. Chest radiograph showed opacity of the right hemithorax due to a large effusion (Fig 1). No pneumonitis was observed. White blood cell count was 13,600/mm3, with 76% polymorphonuclear cells, 9% lymphocytes, 8% monocytes, and 11% eosinophils. Tuberculin testing, blood cultures, and rheumatoid factor testing yielded negative results. Oxygen and intravenous antibiotics were administered for presumed bacterial pneumonia with parapneumonic effusion.

Figure 1. Initial chest film shows large right-sided effusion. No pneumonitis is seen.

A diagnostic and therapeutic thoracentesis was done, with removal of 870 mL of strawberry-colored fluid containing 64% eosinophils (Table). Dyspnea improved for 24 hours, and effusion size diminished by 50% on chest radiographs. A literature search revealed an association between eosinophilic effusions and dantrolene, which the patient had received for 5 years at the maximum dose (400 mg/day) recommended by the Food and Drug Administration. Dantrolene therapy was discontinued on the second hospital day. Symptomatic and radiologic recurrences of the unilateral effusion 2 and 3 days later prompted repeated therapeutic thoracenteses yielding a total fluid removal volume of 1,220 mL. Each subsequent fluid sample contained 60% eosinophils. All cultures were negative for organisms. The patient remained afebrile. The possibility of pneumonia seemed remote. Antibiotics were discontinued.

Upon the third recurrence in 4 days of symptomatic right-sided pleural effusion, the patient refused further thoracenteses due to fatigue and discomfort associated with the procedure. Consultation with a colleague and author of a recent article about EPE5 led to consideration of steroid therapy. After discussion with the patient and pulmonology consultants, consensus was reached for administration of prednisone 40 mg orally for 2 weeks for presumed allergic reaction to dantrolene. Symptomatic improvement followed in 2 days, so that the patient could comfortably lie flat. The large effusion resolved within 3 weeks (Fig 2) and has not recurred in more than 12 months of follow-up. Spasticity has been adequately controlled with diazepam and baclofen.

Figure 2. Chest film 3 weeks later, after dantrolene withdrawal and steroid therapy.

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