A Severe Guillain-Barré Variant Shows Promising Response to Efgartigimod in New Case Report
Acute motor axonal neuropathy, or AMAN, is a severe subtype of Guillain-Barré syndrome, an autoimmune condition in which the immune system mistakenly attacks the peripheral nervous system. Unlike the more common demyelinating form of Guillain-Barré, AMAN targets the axons of motor nerves directly, the long fibers that carry movement signals from the brain to muscles. This distinction matters because axonal damage tends to produce a more intense and rapidly progressing course, and recovery can be slower and less complete than in demyelinating forms of the disease.
People with AMAN typically experience rapidly progressing limb weakness, loss of deep tendon reflexes, and in serious cases, involvement of respiratory muscles that may require ventilator support. The condition is more prevalent in Asia and Latin America than in Western countries, where it accounts for a smaller share of Guillain-Barré cases overall. AMAN is strongly associated with prior Campylobacter jejuni infections, and blood tests often reveal autoantibodies targeting gangliosides, proteins found on the surface of motor nerve axons.
Standard treatment, as with other forms of Guillain-Barré syndrome, consists of intravenous immunoglobulin (IVIg) or plasma exchange, both designed to clear or neutralize the harmful autoantibodies driving the immune attack. A meaningful proportion of patients, however, show incomplete recovery or persistent disability even after these therapies, leaving a real gap in the available options.
A case report published in Medicine (Baltimore) in December 2024 describes a 58-year-old man diagnosed with AMAN who showed limited improvement with both intravenous immunoglobulin and plasma exchange. He presented with ascending symmetrical weakness, flaccid paralysis, and involvement of multiple cranial nerves, and electromyography confirmed the axonal subtype. Because standard therapies were not achieving adequate recovery, his clinicians tried efgartigimod, a drug that works by blocking the neonatal Fc receptor, or FcRn, the recycling system the body uses to extend IgG antibody survival. By inhibiting FcRn, efgartigimod accelerates the breakdown of all circulating IgG, including the pathogenic autoantibodies driving AMAN. The patient received efgartigimod at 10 mg/kg weekly for four weeks and showed significant clinical improvement in muscle strength and nerve conduction studies, with the treatment well tolerated throughout. The authors call for larger clinical trials to confirm whether efgartigimod can be a reliable addition to the treatment toolkit for AMAN patients who don't respond to existing therapies.