Chronic inflammatory demyelinating polyradiculoneuropathy related to neurofascin-155 IgG4 with response to rituximab: case report

Case presentation: Male, 35 years old, with paresthesia in the hands and feet associated with difficulty walking and progressive neuropathic pain in the lower limbs, for approximately 6 months. He underwent intravenous immunoglobulin (IgEv), showing partial improvement in complaints. Physical examination revealed facial diparesis, vibratory hypoesthesia in the malleoli (left better than right). Grade 4 strength in finger flexion and thumb opposition, in addition to plantar flexion and dorsiflexion (4+ in L and 4 in R). Positive Romberg, heel gait with wide base. Electroneuromyography indicating chronic, slightly asymmetric acquired demyelinating peripheral sensory-motor polyradiculoneuropathy, magnetic resonance imaging of the lumbar spine with contrast compatible with inflammatory radiculitis, cerebrospinal fluid with normal cellularity and hyperproteinorrhaquia with a positive Anti-NF-155 test (1/8100 - predominant IgG4 subclass). He underwent two more cycles of IgEv with improvement in pain and sensitivity (improving MIE hypoesthesia and facial weakness), but maintaining ataxia. We chose to undergo three cycles of intravenous corticosteroid therapy and oral immunosuppressant (azathioprine), with partial improvement of all symptoms, with the exception of ataxia. One month later, the patient returned, maintaining previous changes and then underwent 8 plasmapheresis sessions, also with a slight improvement in symptoms. Rituximab was started, on a schedule of 4 weekly infusions of 500 mg, progressing with significant improvement in neurological examination, as well as in functionality. Patient continues to be monitored for discussion of medication dose progression. Discussion: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune-mediated disease that affects roots and peripheral nerves, with a decrease or absence in motor and sensory amplitudes. Around 10% of patients have autoantibodies (mainly IgG4) against nodal and paranodal proteins (NF-155). Because this group of patients with specific antibodies share clinical characteristics and response to treatment different from those of typical CIDP, this disease is included in the recent diagnostic category of autoimmune nodopathy, therefore being a distinct classification from CIDP. In these cases, there is greater distal than proximal muscle weakness, positive sensory symptoms and gait ataxia. Compared to other node-paranodopathies, they have higher recurrence, morbidity and younger age of onset. It is refractory to IgEv, with a favorable response to second-line (Rituximab) and third-line immunosuppressants, and a prolonged time until clinical improvement, up to two years. Final comments: Autoimmune node diseases have a broad clinical spectrum, which makes establishing an effective treatment challenging. Thus, serology for specific autoantibodies makes it possible to use treatment based on the most recent evidence, providing an individualized and effective therapeutic plan.