July 2005

An 11-year-old male is admitted to the hospital with difficulty walking. This was preceded with a few days of fever and nausea. There is no history of trauma, and he was previously healthy with no prior admissions to the hospital. His immunizations are up-to-date.

His examination revealed generalized weakness of the lower extremities, hyperreflexia and clonus. The rest of his exam was essentially normal. A CBC and erythrocyte sedimentation rate (ESR) was done revealing an elevated WBC count and an ESR of 71. Blood cultures are pending.

An MRI of his spine is shown in figures 1-3.

What’s Your Diagnosis?

1. Epidural abscess
2. Vertebral osteomyelitis
3. Diskitis
4. Guillain-Barré syndrome

Answer

The answer is spinal epidural abscess. The clinical presentation shown is fairly typical, and the diagnosis is usually readily made with an MRI, which in this case shows an abscess at the level of T2/T3 (figures 1 & 3). Also seen is some cord compression (figure 2). This is a neurosurgical and infectious disease emergency, needing intravenous antibiotics and surgical drainage, before permanent neurologic sequelae or sepsis and possible death result. Neurologic damage can occur rapidly and may be associated with bacteremic spread to other sites. There may also be local spread to adjacent structures such as the vertebral bodies. The organism is usually Staphylococcus aureus, and empiric therapy should include an anti-staphylococcal antibiotic. Nowadays, that should be an antibiotic effective against community-acquired methicillin-resistant S. aureus (CA-MRSA). This means vancomycin at CNS doses (60 mg/kg/day) should be used initially. Remember, clindamycin should not be used in cases of CNS infections. Also, in most cases, an antibiotic against gram-negative rods should be added pending culture results, especially if the patient has an immune problem. The duration of therapy may need to be several weeks or longer, depending on the clinical course and whether or not there is any bone involvement.

If there is vertebral osteomyelitis present, the involved vertebral body will light up on the MRI, as that shown in figure 4, which, in the case shown happens to be associated with a psoas myositis. Diskitis may present with vague back pain and/or referred pain to the abdomen or chest, depending on the level involved. A diagnosis of diskitis may be made with plain radiographs that show disk space narrowing (figure 5), which is often difficult to see by the untrained eye. But again, MRI is fairly definitive (figure 6, same patient as figure 5), and even I can see it. The bone scan will also usually reveal the diagnosis, but is being quickly replaced with MRI as the imaging-of-choice where available. Treatment is also an anti-staph antibiotic for a variable time, again depending on bone involvement or not.