FROM MUSCLE & NERVE
Patients with an acute transient immune response that is directed against small nerve fibers can display features similar to those of Guillain-Barré syndrome, according to Nobuhiro Yuki, PhD, and associates.
The investigators described three Chinese patients with severe pain in their extremities weeks after infectious illness. Pain greatly improved in two of the patients within days (up to 1 week) of treatment with intravenous immunoglobulin. One patient who refused intravenous immunoglobulin gradually improved with 3 weeks of prednisolone treatment but did not improve as much as the other two.
The investigators found that intrathecal injections of the sera from the acute phase of these patients’ illnesses into nociceptive thermal mouse models induced a transient thermal hypersensitivity, whereas sera from 25 patients with Charcot-Marie-Tooth disease and 25 patients with chronic inflammatory demyelinating polyneuropathy who served as disease controls did not. The intrathecal injections of sera from a healthy donor or from the first two of the three described patients after recovery did not affect thermal sensitivity.
Also, patients’ sera in the acute phase strongly and widely stained small nerve fibers in the dermis of the foot pads of the mice and colocalized with a nerve marker. The sera did not react against myelinated fibers from mouse sciatic nerves. Serum IgG antibodies immunostained the dorsal horn of the lumber spinal cord during the acute phase in all patients, but none of the patients showed reactivity in the convalescent phase.
Patients’ IgG antibodies reacted against surface antigens from the neuron cell body and axon from patients’ sera, but none of the patients with Charcot-Marie-Tooth or chronic inflammatory demyelinating polyneuropathy presented a similar reaction against dorsal root ganglion neurons.
“Our case series and the cases identified in the literature suggest that an acute immune response can be directed against small fibers and exhibit similarities to Guillain-Barré syndrome, including acute preceding infectious illness, a monophasic course, and albuminocytologic dissociation,” the researchers concluded. “It is also worth pointing out that patients with ‘acute small fiber sensory neuropathy’ subsequent to infection or vaccination do not always complain of pain, suggesting a different disease entity.”
Read the full study in Muscle & Nerve (2017. doi: 10.1002/mus.25738 ).
