In the entire study cohort, only one patient with CBS had anti-IgLON5 antibodies. This patient was a 78-year-old female with a 4-year history of slowly progressive left-sided impairment of dexterity and gait disturbance. Neurological examination showed rigidity, dystonia in left limb, left-sided apraxia, cortical sensory deficit, and gait disturbance. She was diagnosed with probable corticobasal degeneration (CBD) based on the consensus criteria proposed by Armstrong and colleagues. The patient was treated with intravenous methylprednisolone pulse therapy for three days, followed by two courses of intravenous immunoglobulin therapy for five consecutive days; the latter led to gradual improvement of apraxia, gait disturbance, and cortical sensory deficits. Additionally, significant improvement in tracer uptake was observed with single-photon emission computed tomography using ¹²³I-N-isopropyl-p-iodoamphetamine and dopamine transporter.