Central nervous system infections in cancer patients.

In the immunocompromised patient, even mild forms of any combination of headache, meningismus, altered mental status, or focal neurologic signs should initiate an evaluation for possible CNS infection. The limited signs and symptoms of acute CNS infection are not due to specific organisms but to pathologic changes at the neuroanatomic site of infection. The initial clinical history, examination, laboratory, and neuroradiographic data will narrow the problem to one of several groups of agents, although it may not be possible to specify a single causative agent. It should be remembered that several concurrent infections (i.e., CMV and toxoplasmosis, aspergillosis, and bacterial sepsis) may be present. Thus, the clinician should rely on broad antibiotic coverage appropriate to the suspected causative agent or agents at the site of infection. It may be necessary to offer broad-spectrum antibiotic coverage for a CSF presentation that is subsequently found to result from a viral illness or from a noninfectious cause. However, one should avoid undertreating those infections for which specific therapy can be offered, and broad-spectrum treatment usually will not be regretted. Uncertainty in diagnosis following noninvasive procedures should lead to a brain biopsy. Although many of the infections discussed in this article have a poor prognosis, some of the most common pathogens, such as Cryptococcus, Listeria, and Toxoplasma, have effective specific therapies to which the patient should have access as rapidly as possible. The clinician who has successfully treated a patient with CNS infection should remain vigilant for late sequelae or recurrence of infection. Chronic treatment of some infections, such as toxoplasmosis or aspergillosis, may be necessary. The reintroduction of steroids for the treatment of an underlying cancer may reactivate previously treated disease, such as cryptococcosis, and periodic CSF surveillance is appropriate under these circumstances. Recurrence of the symptoms should raise the suspicion of recurrent or new infection, and the patient also should be evaluated with CT or MRI for the development of hydrocephalus or for new metastatic disease. In patients who have had varicella-zoster infection, postherpetic neuralgia and delayed arteritis may develop. Seizures, hearing loss, and neuropsychologic sequelae may follow any meningoencephalitis. The patient should always be reevaluated for the possibility of infection with a different opportunistic organism. CNS infections remain a major cause of morbidity and mortality in immunosuppressed patients with malignancies. In one series, 60% of such patients died as a result of their CNS infection, many at a time when the underlying disease had an otherwise good prognosis.(ABSTRACT TRUNCATED AT 400 WORDS)