An October 21 report in Neurology News described outbreaks in California and Colorado, suggesting that the number of cases might be 100 or more nationwide. Diagnosis included a good medical history, MRI imaging, and the elimination of transverse myelitis or Guillain–Barré syndrome as potential causes. Physicians were using a listserv online mailing list to communicate about similar cases in Alabama and Kansas. The largest known cluster of cases was in Colorado, with 29 total, 12 of which were reported since August.
Three out of four cases treated in Alabama involved a complete inability to move one arm, reminiscent of peripheral nerve injury:
The three cases since August really look like each other. They have severe arm flaccidity and no mental status changes. All of them have similar spine MRIs showing gray matter involvement. You could lay all three MRIs on top of each other and they look almost the same. It's pretty striking. ... It you lift the arm up, it literally drops. Sensation is usually intact.
Three out of four cases treated in Alabama involved a complete inability to move one arm, reminiscent of peripheral nerve injury:
The three cases since August really look like each other. They have severe arm flaccidity and no mental status changes. All of them have similar spine MRIs showing gray matter involvement. You could lay all three MRIs on top of each other and they look almost the same. It's pretty striking. ... It you lift the arm up, it literally drops. Sensation is usually intact.