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Suspected AFM awaiting hx/exam
Suspect AFM if sudden-onset flaccid limb(s), esp Aug-Nov (↑cases in even-numbered years1,2), in pts w/ preceding viral sx.3 90% are young children. Neuro exam may show cranial nerve, autonomic involvement. If AFM suspected, immediately admit to hospital, seek neuro +/- ID consult1 - Hx: sudden/rapid-onset acute flaccid limb weakness developing over hours/days in ≥1 limb. May have HA, stiff/painful neck, pain in affected arm/leg or back.1,3 May have difficulty w/ gait, speech/swallowing,2 ↑sleepiness, inactivity, inability to pass urine. Uncommonly, numbness or tingling1,3
- Preceding hx: >90% have febrile illness w/in 1-2wk prior to limb weakness; eg, resp/GI illness w/ fever, rhinorrhea, cough, vomiting, diarrhea. Non-polio enteroviruses, etc, have been implicated.3 No evidence suggests preceding vaccinations causative1
- Vitals: ✓resp sufficiency (may rapidly progress to resp failure), temp changes, BP instability (can be life threatening)3
- Limb exam:2,3 ✓muscle strength (against gravity, resistance; proximal may be worse than distal weakness), ↓muscle tone (loose/flaccid), ✓reflexes, ✓abnl gait. Sensory exam often NL
- Cranial nerve: difficulty moving eyes, eyelid droop, facial droop/weakness,1 difficulty swallowing/speaking, hoarse/weak cry,3 neck weakness2
- Consider differential: limb injury, transverse myelitis, Guillain-Barre, synovitis, neuritis, stroke/spinal stroke, tumor, acute cord compression, conversion disorder3
Footnotes 1 About Acute Flaccid Myelitis. Centers for Disease Control and Prevention. Last reviewed: 2/25/20. Accessed 10/17/10
• Even-numbered years. CDC observed that increases in AFM cases since 2014 coincide w/ increases in enterovirus circulation, & in 2014, w/ a national outbreak of resp illness caused by EV-D68. A mix of enteroviruses circulates every year, & different types of enteroviruses can be common in different years, so may contribute to AFM increases every 2y.
• Vaccination hx. Of AFM cases reviewed in 2018, ~85% had no recorded vaccinations in 30 days prior to onset of limb weakness. Vaccine records showed average time between last vaccine & AFM sx (ie, limb weakness) was almost 2y.
2 Acute Flaccid Myelitis. Vital Signs. Centers for Disease Control and Prevention. August 2020. Full-text article
• Enteroviruses, particularly EV-D68, are likely responsible for the increase in cases every 2y since 2014.
3 Acute Flaccid Myelitis (AFM): Clinical Guidance for the Acute Medical Treatment of AFM. Centers for Disease Control and Prevention. Last reviewed: 10/2/20. Accessed 10/17/20
• Viral causes include non-polio enteroviruses (EV-D68, EV-A71); flaviviruses (West Nile virus, Japanese encephalitis virus); herpesviruses; adenoviruses. Though clinical presentation is similar to poliomyelitis, poliovirus not detected in specimens from AFM pts.
• Upper limb fxn hx: use of arms/hands, feeding self, suddenly refusing to use a limb or using it less, ability to raise arm above head, put on/remove t-shirt, throw ball overhead
• Lower limb fxn hx: limping, dragging leg, falling often while walking, unable to rise unassisted from sitting/squatting or being in tub, put on/remove pants
• Non-limb fxn hx: difficulty holding up head, ↓appetite, difficulty swallowing, ↑sleepiness, inactivity, HA, neck/shoulder/back pain (may precede/coincide w/ weakness), pain in extremities, bowel/bladder change (esp constipation)
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Awaiting tests (MRI, CSF, etc) after hx/exam
If AFM suspected, admit to hospital immediately.1 Consult neuro, ID, order MRI; obtain specimens ASAP.2 Depending on age, may require sedation; sequence tests to avoid repeat sedation, continuously monitor resp status. Contact health dept to arrange for sending specimens to CDC3 - Imaging: MRI spine & brain w/ & w/o contrast, highest Tesla scanner available (eg, 3T), axial & sagittal images. Consider entire spine; if cranial nerve deficits, consider high cuts of brainstem or total brain. MRI may be NL w/in 1st 72h of limb weakness, so repeat if clinically indicated. AFM lesions predominantly in gray matter; may have white matter involvement3
- CSF cell count w/ diff, protein, glucose; oligoclonal bands; meningitis/encephalitis PCR panel3
- Serum: EV PCR,4 anti-MOG & anti-aquaporin ab, HSV, EBV, WNV3
- Stool/rectal swab EV PCR3
- Nasopharyngeal &/or oropharyngeal swabs: resp multiplex testing & EV PCR3
- Additional tests for infxns: Consider pathogen-specific testing (eg, Lyme) per seasonality, exposures, geography, & clinical presentation. Rapid specimen collection increases chance of pathogen detection3
- Assess per case criteria: sudden-onset flaccid limb weakness w/o known cause + MRI w/ spinal cord gray matter lesions3
- Contact local health dept to arrange for sending specimens & MRI results to CDC3
Footnotes 1 CDC Expects 2020 Outbreak of Life-Threatening Acute Flaccid Myelitis. Centers for Disease Control and Prevention. Issued: 8/4/20. Press release
• AFM can progress rapidly over hours/days, leading to permanent paralysis &/or life-threatening resp failure in previously healthy pts.
2 Acute Flaccid Myelitis: Specimen Collection Instructions. Centers for Disease Control and Prevention. Last reviewed: 1/31/20. Accessed 10/17/20
• Collect specimens from pts under AFM investigation ASAP, preferably on day of limb weakness onset, for best chance to detect a cause of AFM. If specimens weren’t collected or no specimen remains, repeat specimen collection when feasible. Specimen collection specifics detailed at CDC.gov.
3 Acute Flaccid Myelitis (AFM): Clinical Guidance for the Acute Medical Treatment of AFM. Centers for Disease Control and Prevention. Last reviewed: 10/2/20. Accessed 10/17/20
Case definition = clinical + imaging criteria
• Clinical: sudden-onset flaccid limb weakness (ie, low muscle tone, limp, hanging loosely, not spastic/contracted)
• Imaging: MRI w/ spinal cord lesion in @ least some gray matter (eg, affecting mostly gray matter or anterior horn/anterior horn cells or central cord; anterior myelitis, poliomyelitis) spanning ≥1 vertebral segments, excluding pts w/ spinal cord gray matter lesions resulting from diagnosed malignancy, vascular dz, or anatomic abnormalities
4 Acute Flaccid Myelitis. Vital Signs. Centers for Disease Control and Prevention. August 2020. Full-text article
• Enterovirus. Pts who tested positive for EV-D68 typically had more severe AFM, requiring ICU care, ventilation.
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AFM clinical criteria met, awaiting tx
Immediately admit to hospital1 pts who meet AFM clinical + imaging criteria,2 as rapid paralysis, resp failure may ensue. Seek neuro +/- ID consult. No specific tx proven.1 Collect specimens ASAP,3 report to health dept4 - ✓Resp status. Assess & monitor resp sufficiency. Negative inspiratory force may be used if child old enough, able to cooperate2
- Tx: There’s no clear evidence for/against any specific tx for acute AFM. These frequently tried alone/in combo: IVIG, steroids, plasma exchange5
- No indication for use of these in AFM: fluoxetine, antivirals, interferons, or other immunosuppressives/biologics. Some agents may theoretically impair immune rxn to infxn5
- OT/PT may be recommended for arm/leg weakness. Physical rehab implemented during initial phase of illness might improve long-term outcomes1
- Infxn control: standard + contact + droplet precautions, consistent w/ EV-D68 recommendations5
- Contact local health dept to arrange for sending specimens (CSF, serum, naso-/oro-pharyngeal, stool/rectal)3,6 & MRI results to CDC2
- Prognosis: Deaths have been reported in acute phase of illness;1 AFM can lead to permanent paralysis & disability4
Footnotes 1 About Acute Flaccid Myelitis. Centers for Disease Control and Prevention. Last reviewed: 2/25/20. Accessed 10/17/10
2 Acute Flaccid Myelitis (AFM): Clinical Guidance for the Acute Medical Treatment of AFM. Centers for Disease Control and Prevention. Last reviewed: 10/2/20. Accessed 10/17/20
Case definition = clinical + imaging criteria
• Clinical: sudden-onset flaccid limb weakness (ie, low muscle tone, limp, hanging loosely, not spastic/contracted)
• Imaging: MRI w/ spinal cord lesion in @ least some gray matter (eg, affecting mostly gray matter or anterior horn/anterior horn cells or central cord; anterior myelitis, poliomyelitis) spanning ≥1 vertebral segments, excluding pts w/ spinal cord gray matter lesions resulting from diagnosed malignancy, vascular dz, or anatomic abnormalities
3 Acute Flaccid Myelitis: Specimen Collection Instructions. Centers for Disease Control and Prevention. Last reviewed: 1/31/20. Accessed 10/17/20
Collect specimens from pts under AFM investigation ASAP, preferably on day of limb weakness onset, for best chance to detect a cause. If specimens weren’t collected or no specimen remains, repeat specimen collection when feasible. Specimen collection specifics detailed at CDC.gov.
4 Acute Flaccid Myelitis. Vital Signs. Centers for Disease Control and Prevention. August 2020. Full-text article
• Enterovirus. Pts who tested positive for EV-D68 typically had more severe AFM, requiring ICU care, ventilation.
5 Acute Flaccid Myelitis: Clinicians & Health Departments. Centers for Disease Control and Prevention. Last reviewed: 7/13/20. Accessed 10/17/20
Tx frequently used
• IVIG. There’s no indication that IVIG should be either preferred or avoided in AFM. No clear human evidence for efficacy; no evidence that IVIG is likely to be harmful.
• Corticosteroids. There’s no indication that corticosteroids should be either preferred or avoided in AFM. No clear human evidence for efficacy. Possible benefits of managing spinal cord edema or white matter involvement should be balanced w/ potential harm due to immunosuppression in the setting of possible viral infxn.
• Therapeutic plasma exchange. There’s no indication that plasma exchange should be either preferred or avoided in AFM. No clear human evidence for efficacy. Although inherent procedure-associated risks exist, there’s no evidence it’s likely to be harmful.
6 Acute Flaccid Myelitis (AFM): Clinical Guidance for the Acute Medical Treatment of AFM. Centers for Disease Control and Prevention. Last reviewed: 10/2/20. Accessed 10/17/20
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