Acute Flaccid Myelitis: Understanding the Recent Outbreak – Q&A with Dr. Benjamin Greenberg and Dr. Teri Schreiner
With the recent increase in reports of children being hospitalized due to a respiratory virus, enterovirus D68, there have been many reported cases of acute myelitis from across many states in the US. Dr. Benjamin Greenberg from University of Texas Southwestern and Dr. Teri Schreiner from Children’s Hospital Colorado joined us for a podcast on the topic to share their experience. The podcast can be downloaded at https://wearesrna.org/resources/update-on-outbreak-of-paralysis-in-us-acute-flaccid-myelitis/.
Drs. Greenberg and Schreiner respond to more questions from the community in this blog.
Post-infectious or Infectious Transverse Myelitis has been described before in the scientific literature. How are these cases of acute flaccid myelitis different?
Dr. Greenberg: The traditional description of transverse myelitis is inflammation of the spinal cord, but over the last 50 years, this term has been used when specifically describing immune mediated damage to certain parts of the spinal cord – specifically white matter. For years we used the term transverse myelitis and described it to patients and colleagues as an immune-mediated disorder, probably post-infectious leading to demyelination of the spinal cord white matter. What is being recognized now are the number of cases, specifically in pediatric patients, that target the gray matter, some of which may be the result of direct infection of spinal cord cells.
Dr. Schreiner: The cases of Acute Flaccid Myelitis (AFM) are distinct because of the pattern of spinal cord involvement. What we are seeing is that limbs of patients are weak and flaccid or limp, but not spastic. The MRI of these patients shows that only one part of the spinal cord – called the gray matter – is inflamed. Sensation is preserved in these patients, there is no difficulty with bladder or bowel function, and many patients have also noted difficulty with facial weakness, weakness of the muscles that move the eyes or muscles used for swallowing or speaking.
What is the treatment protocol for acute flaccid myelitis?
Dr. Schreiner: Unfortunately, none of the treatments that we use commonly for acute myelitis have shown much effect with Acute Flaccid Myelitis. We have used high dose intravenous steroids, IVIg and plasmapheresis. We have also tried an experimental anti-viral medication. None of these have had a discernable effect. As in TM, we believe that physical therapy remains a very important tool for recovery.
Dr. Greenberg: Treatment also has to be individualized to each patient. Most patients require supportive care including feeding and breathing support. Some patients may have swelling or inflammation in the spinal cord that could benefit from therapies such as steroids, IVIg or plasma exchange. These remain unproven in this cohort of patients.
Is the recovery similar to that from Transverse Myelitis?
Dr. Greenberg: So far, in my experience, the recovery is different. Patients with damage to the gray matter have a different pattern of weakness and different issues during recovery. They don’t respond to the same therapeutic approaches, but may benefit from specific interventions over time. For example, some patients may benefit from nerve transplant procedures in the setting of gray matter damage.
Dr. Schreiner: Among the 13 patients that we have seen in Colorado, the recovery has been slow to date. Most patients have improved slightly over time, but no one has returned to their baseline prior to AFM. It is important to note, however, that only 2 months have elapsed since onset of weakness in most cases. We may find that improvements continue over a much longer timeframe.
Does this always cause paralysis?
Dr. Schreiner: Weakness is a cardinal feature of these patients. The weakness may be in the arms, legs, face, oral or eye muscles. The weakness can vary from subtle to very severe.
Dr. Greenberg: We are tracking cases of total paralysis, partial paralysis and weakness of just one limb. The combinations and presentations have been quite variable.
Are there any restrictions to getting a vaccination when diagnosed with acute flaccid myelitis?
Dr. Greenberg: There are no specific contraindications. We tend not to vaccinate children when acutely ill in the hospital, but after discharge it is safe.
Dr. Schreiner: If the child has received steroids during his/her hospitalization it may be prudent to wait a few weeks before vaccination.
Have there been myelitis cases reported in adults from enterovirus D68 infection?
Dr. Schreiner: California has reported seeing similar cases in adults. However, it is not known whether these patients have tested positive for EV-D68. Moreover, although EV-D68 is the suspected pathogen, we cannot say definitively that EV-D68 is causing the cases of paralysis.
Dr. Greenberg: There have been cases of myelitis in adults who have had enterovirus infections. We are working to confirm if it is the D68 subtype or others. Also, as noted by Dr. Schreiner, the relation to enterovirus D68 is a theory – substantiated by significant evidence, but remains to be conclusively proven.
In children and adults who have been diagnosed with Transverse Myelitis, will an enterovirus infection cause a recurrence of the disease?
Dr. Schreiner: We have no reason to believe that a patient previously affected by TM would be at any greater risk of AFM.
Dr. Greenberg: I agree, based on our experience and the available data – no. The myelitis in the setting of enterovirus is VERY rare and we have not seen cases of recurrence.
What can we do to prevent acute flaccid myelitis?
Dr. Schreiner: Simple measures like washing your hands, coughing into your sleeve, and staying away from sick persons will help to prevent the spread of the virus.
Is the CDC currently monitoring these cases and is there a plan for the future?
Dr. Greenberg: The CDC has an active surveillance program underway and there is a collaboration among clinical centers in North America to explore these cases in detail. We are working to prove causation as best as possible and then focus on prevention and advanced therapeutics.
Dr. Schreiner: More information is available at: https://www.cdc.gov/ncird/investigation/viral/sep2014.html.
