Top 5 Takeaways

  1. This report details two cases of encephalomyelitis associated with monkeypox (MPXV) infections in previously healthy gay men in Colorado and DC.
  2. Both cases showed neurological complications, including extremity weakness, urinary retention, and cognitive decline, following MPXV infection.
  3. Magnetic resonance imaging (MRI) findings were consistent with demyelination and encephalomyelitis in both cases, but MPXV nucleic acid was not found in cerebrospinal fluid (CSF).
  4. The exact pathophysiology of encephalomyelitis in these cases is unclear, whether due to direct viral neuroinvasion or a parainfectious autoimmune process.
  5. The report emphasizes the need for reporting suspected neurological complications of MPXV to health departments for better understanding and management.


This MMWR Article was created prior to the conventional renaming of Monkeypox to its more standard and appropriate name, Mpox. To avoid confusion, Monkeypox is retained when writing this article, but all future works should use Mpox.


Original Article Author and Citation

Corresponding Author

Daniel M. Pastula,

Suggested Citation

Pastula DM, Copeland MJ, Hannan MC, et al. Two Cases of Monkeypox-Associated Encephalomyelitis — Colorado and the District of Columbia, July–August 2022. MMWR Morb Mortal Wkly Rep 2022;71:1212–1215. DOI: .


The article describes two cases of encephalomyelitis in young gay men following MPXV infection. Notably, neither had a known exposure to MPXV or recent travel history. The patients developed symptoms typical of MPXV, followed by neurological issues. MRI results supported a diagnosis of encephalomyelitis. However, CSF tests for MPXV were negative, leaving the exact cause of encephalomyelitis unclear.


The report employed patient clinical care data and public health outbreak response information. MRI and CSF analyses were critical in diagnosing encephalomyelitis. Data collection was compliant with relevant laws and CDC policy.


The cases highlight an atypical presentation of MPXV with severe neurological complications. The absence of MPXV nucleic acid in CSF suggests that neuroinvasion might not be the direct cause. The report speculates on possible pathophysiological mechanisms, including parainfectious autoimmune processes.


These cases underscore the importance of considering and reporting neurological complications in MPXV infections. Further research is necessary to understand the pathogenesis of encephalomyelitis in MPXV and to develop effective treatment strategies.

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