“We are aware that relapses in MS are frequently triggered by infections; about a third of relapses are known to be preceded by infections. These are typically viral infections.We have no idea how many relapses are triggered by reactivation of dormant viral infections, such as VZV, CMV and EBV. The latter is one of the hypotheses underpinning the viral hypothesis of autoimmunity, i.e. that viral infections drive autoimmunity by stimulating or boosting the immune system that allows the autoimmune cells to be easily triggered to damage self. How do we test this hypothesis? It may have been tested already, but we don’t know it. Does interferon beta and interferon alpha, which are antiviral agents work in MS by suppressing viral infections? Some of the original data on exogenous viral infections (colds, flu, etc.) suggests that interferon-beta does not reduce these types of infections, but we don’t have data on the impact of these agents on reactivation of persistent viral infections, in particular EBV. As part of the Charcot Project we are hoping to get some information on this.”
“Anecdotally, I have looked after a few patients who have had a strong temporal relationship between herpes virus reactivation and relapse. Two of these patients noticed a major reduction in their relapses when they were put onto long term antiviral drugs by their virologists. Interestingly, their relapses were stereotypical suggestive of a MS lesion been reactivated at the same site in the spinal cord. The latter may therefore have simply been a pseudorelapse due to conduction block in a demyelinated pathway rather than a true relapse. This is why it is so hard to do research in this area; sorting out pseudorelapses from true relapses is not easy.”
Torkildsen et al. Detection of varicella-zoster virus DNA during medullary and brainstem relapses in multiple sclerosis. BMJ Case Rep. 2016 Feb 23;2016. pii: bcr2016214555. doi: 10.1136/bcr-2016-214555.
We describe three cases of patients with concomitant acute medullary or brainstem multiple sclerosis (MS) lesions and detectable spinal fluid varicella-zoster virus DNA. Herpes simplex virus PCR was also positive in two of the patients. One patient was re-punctured 2 weeks following the relapse, with negative results. The PCR findings greatly delayed correct diagnosis and treatment in all three patients. Based on our cases, we propose that inflammatory medullary and brainstem lesions could result in viral leakage, and possibly viral reactivation, from destroyed sensory neurons, yielding false-positive cerebrospinal fluid PCR results. As this can have diagnostic and therapeutic consequences, further studies are warranted to evaluate the clinical relevance of these findings.