SIR: Drs. Patel and Friedman presented a cogent and informative discussion of the neuropsychiatric features of acute disseminated encephalomyelitis.1 The section on differential diagnosis, however, mistakenly included syphilis and Lyme disease under the category of viral encephalitides. Both syphilis and Lyme disease are in fact caused by bacteria—in particular, spirochetes.
Further, although acute and convalescent titers can be very helpful in monitoring the course of syphilis, the serologic or CSF test results in Lyme disease are less reliable.2 This is of critical importance among patients with Lyme-induced encephalomyelitis. Some patients may have a positive CSF polymerase chain reaction assay for Borrelia burgdorferi (the agent of Lyme disease) or positive immune complex dissociation studies but have an otherwise normal-appearing CSF and equivocal or nonreactive serum.3 Although serologic and CSF titer monitoring is routinely done in the European strains of Lyme encephalomyelitis to monitor progress in the treatment of the disease, the CSF of patients with neurologic Lyme disease in North American strains is less often abnormal initially and therefore less helpful for serial monitoring.3,4
In endemic areas or in patients with a clinical history suggestive of neuropsychiatric Lyme disease, we urge physicians therefore to consider Lyme disease as a treatable cause of persistent encephalomyelitis even in cases where the CSF or serologic results are negative or equivocal.5