1990 and July 1992). In one patient transverse myelitis developed after administration of Td, and in another patient transverse myelitis developed after administration of Td and hepatitis B vaccine. The temporal and clinical details provided in these reports from VAERS are insufficient for proper evaluation of the cases.
Well-documented cases of optic neuritis following vaccine administration are even rarer than cases of transverse myelitis. Quast et al. (1979) reported a 46-year-old man who developed acute optic neuritis 10 days after receiving a tetanus booster. As discussed above, Topaloglu et al. (1992) described an 11-year-old girl who developed transverse myelitis and optic neuritis 3 days after receipt of a tetanus booster. No cases of solitary optic neuritis in association with tetanus toxoid, DT, or Td were found in VAERS (submitted between November 1990 and July 1992).
There is biologic plausibility for a causal relation between vaccines and demyelinating disorders. The reports in the literature that describe a possible association between demyelinating diseases of the CNS (ADEM, transverse myelitis, and optic neuritis) are case reports. There are at least two case reports in the literature for each of the above-mentioned demyelinating diseases of the CNS. The case reports describe the demyelinating disease that occurs within the biologically plausible latency period of 5 days to 6 weeks, and the case reports provide enough clinical detail that one can be relatively certain of the neurologic diagnosis. What the case reports cannot address is whether the frequency of the cases that occurred was greater than the expected background rate for these specific demyelinating diseases. Annual incidence rates have been estimated for transverse myelitis (Beghi et al., 1982). These data were calculated for Rochester, Minnesota, for the years 1970 to 1980. The estimated rate of 0.83 per 100,000 individuals is much higher than a rate calculated for Israel, presumably because of differences in hove successful the two studies were at identifying all cases of transverse myelitis. No population-based incidence rates for ADEM or optic neuritis were identified. This question is difficult at best for rare adverse events and can be answered only if both good age-specific background rates for the