A Tale Of Two Diagnoses

Contributed by readers • Edited by Sheldon Jacobson, MD

A 65-year-old woman was transferred to an ED from another institution due to a lack of inpatient beds. She had presented to that hospital with complaints of fever, chills, and burning chest pain of approximately two days' duration. The chest pain radiated into her middle back and did not have a pleuritic or positional component. Prior to transfer, the patient had normal results on ECG, chest x-ray, and one set of cardiac enzymes. The urinalysis, however, had been consistent with a urinary tract infection, and that was the presumptive diagnosis at transfer.

The patient was an insulin-dependent diabetic with no history of heart disease, renal disease, or substance abuse. She denied having recent abdominal pain, nausea, vomiting, diarrhea, flank pain, dysuria, cough, or symptoms of a viral illness. She had not experienced previous episodes of that particular chest pain.

On arrival, her vital signs were a temperature of 100.4° F, respirations 20, blood pressure 100/88 mm Hg, and pulse 120 and regular. Pulse oximetry on room air revealed 94% saturation. Her pain score was 6/10. Her lungs were clear, but breath sounds were distant. Cardiac and abdominal examinations were normal. On neurologic evaluation, the patient was alert and oriented and her verbal responses were appropriate. Moderate resistance to neck flexion was noted, and flexion increased her neck and back pain. The remainder of the neurologic examination was nonfocal.

A repeat urinalysis, this time of a specimen obtained by catheter, was normal. Serum chemistry results included: glucose level, 346 mg/dl; CO₂, 22 mEq/L; BUN, 26 mg/dl; and creatinine, 1.6 mg/dl. Complete blood count revealed a WBC of 13,200/mm³. Considering the meningeal findings and the negative urinalysis, the emergency physician's working diagnosis became meningitis. A lumbar puncture revealed slightly turbid fluid, with 565 WBC/mm³, predominantly polymorphonuclear leukocytes, in the CSF. The protein was 350 mg/dl and the glucose 75 mg/dl.

Ceftriaxone and ampicillin were started in the ED, and the patient was admitted to the medical floor. The emergency physician felt a sense of satisfaction because he had not just accepted the transferring physician's diagnosis, but had repeated the evaluation and discovered the meningitis—despite the absence of typical symptoms such as headache, nausea, and vomiting. This sense of satisfaction evaporated several days later, however, when he learned that paraparesis had developed and that an MRI of her spine had revealed an epidural abscess at the level of T4-5. Surgical decompression was performed, but the patient was left with mild residual paraparesis.
 

DISCUSSION

In this case, recognition of the epidural abscess was delayed initially because of a contaminated urine specimen and subsequently because the ED physician simply did not consider the problem in his differential diagnosis of central nervous system infections. He also failed to connect the chest pain with the febrile illness. Back pain, of course, is a more typical presenting symptom in spinal epidural abscess. In retrospect, it is apparent that the chest pain was a component of the radiculopathy of the root compression. Such pain is usually experienced as a sharp burning in belt-like circumferential distribution. The meningeal irritation was probably a manifestation of the spinal abscess known by the eponym Lhermitte's sign. Seen both in space-occupying lesions of the spinal canal and in multiple sclerosis, Lhermitte's sign is shocklike pain radiating down the spine when the neck is flexed.

The differential diagnosis of the simultaneous presentation of fever and back pain in an immunocompromised person, parenteral drug abuser, alcoholic, or diabetic should always include epidural abscess. Other important diagnoses to consider include aortitis, endocarditis, metastatic spread of infection from dental abscess, pharyngitis, decubitus ulcers, lung abscess, perinephric abscess, mediastinitis, discitis, and isolated vertebral osteomyelitis. Approximately 50% of patients with spinal epidural abscess have coexisting vertebral osteomyelitis.

The most common pyogenic organism in spinal epidural abscess is Staphylococcus aureus, followed by streptococci of both aerobic and anaerobic varieties. Mycobacterium tuberculosis, Aspergillus, and Echinococcus species, and cryptococcosis have all been reported to cause both osteomyelitis and epidural abscess in chronically infected hosts. In addition to appropriate antibiotic coverage, surgical decompression of the abscess as early as possible is key to preventing spinal cord infarction and permanent loss of function below the lesion.