Neurosyphilis is an easily missed cause of encephalopathy
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* Aravind Ganesh

I enjoyed reading Dr. Budhram and colleagues’ case report on neurosyphilis mimicking autoimmune encephalitis.1 I thank the authors for bringing attention to this important (albeit uncommon) presentation, which can be easily missed or forgotten unless it is ingrained in our minds as part of the workup for these types of subacute encephalopathic presentations. For example, as part of *Neurology*’s educational outreach efforts, we recently surveyed neurologists and residents on the differential diagnosis of a real-life case of a 64-year-old woman with neurosyphilis who similarly presented with subacute encephalopathy (but no seizures) and had bilateral mesial temporal lobe hyperintensities.2 Nearly half of the respondents recognized the importance of considering paraneoplastic and autoimmune causes in this presentation and a third recognized herpes encephalitis as another potential cause, but only 14% considered neurosyphilis in their differential diagnosis or workup. In the absence of reliable data, it is difficult to know the extent to which neurosyphilis is missed in clinical practice, but case reports like that by Budhram and colleagues in general medical journals such as *CMAJ* will hopefully serve as a reminder to both general and specialist clinicians to incorporate this curable condition into their standard workup for encephalopathy.

## Footnotes

*   **Competing interests:** Aravind Ganesh is on the editorial board of *Neurology*’s Residents and Fellows section.

## References

1.  Budhram A, Silverman M, Burneo JG. Neurosyphilis mimicking autoimmune encephalitis in a 52-year-old man. CMAJ 2017;189:E962–5.
    
    [FREE Full Text](http://www.cmaj.ca/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiRlVMTCI7czoxMToiam91cm5hbENvZGUiO3M6NDoiY21haiI7czo1OiJyZXNpZCI7czoxMToiMTg5LzI5L0U5NjIiO3M6NDoiYXRvbSI7czoyMzoiL2NtYWovMTg5LzQ1L0UxNDAxLmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 

2.  Bhai S, Biffi A, Bakhadirov K, et al. Mystery Case: a 64-year-old woman with subacute encephalopathy. Neurology 2015;85:e64–5.