A Case of Acute‐Onset Chronic Inflammatory Demyelinating Polyradiculoneuropathy Occurring During a Flare of Chronic Immune Thrombocytopenia

A 51‐year‐old woman with relapsing immune thrombocytopenia developed rapidly progressive limb weakness, sensory disturbance, and areflexia after diarrhea. Nerve conduction studies revealed demyelinating sensorimotor polyneuropathy, and Guillain‐Barré syndrome was initially diagnosed. While the symptoms resolved completely following intravenous immunoglobulin and oral prednisolone therapy, the limb weakness and sensory disturbance recurred 14 weeks after the initial neurological symptom onset. The relapsing course beyond 8 weeks, together with typical clinical features and electrodiagnostic abnormalities in two motor and two sensory nerves, supported a diagnosis of typical chronic inflammatory demyelinating polyradiculoneuropathy rather than Guillain‐Barré syndrome. Intravenous immunoglobulin, methylprednisolone pulse, plasma exchange, and subsequent oral prednisolone therapy led to improvement. Notably, the exacerbations of immune thrombocytopenia paralleled the initial neurological worsening and subsequent recurrence, with polyclonal serum IgG elevation observed before immunotherapy on both occasions. This case raises the hypothesis that shared immune activation may underlie the two disorders.