Lumbar spine magnetic resonance imaging (MRI) showed mild herniated disc at lumbar segments 4 and 5 (L4CL5) and lumbar segment 5 and sacral segment 1 (L5CS1). as having chronic inflammatory demyelinating polyneuropathy and treated with intravenous immunoglobulin and prednisone. However, his condition got WIKI4 worse. One?month later, he was diagnosed with chronic inflammatory demyelinating polyneuropathy associated with anti-contactin-associated protein 1 antibody. He received high-dose methylprednisolone, followed by standard plasma exchange and rituximab therapy. His sensory and motor manifestations were significantly improved at 1?year of follow-up. Conclusions This case reminds clinicians to be aware of antiparanodal antibodies, which are associated with specific phenotypes and therapeutic response. Keywords: Chronic inflammatory demyelinating polyradiculoneuropathy, Autoantibody, Contactin-associated protein 1, Bile duct hamartomas in liver Background Chronic inflammatory demyelinating polyneuropathy (CIDP) is usually a heterogeneous Rabbit Polyclonal to RPC3 chronic autoimmune neuropathy characterized by chronic progressive motor and sensory deficits during a period of at least 8?weeks [1, 2]. CIDP diagnosis is based on clinical and electrophysiological criteria [2]. Humoral factors are involved in the mechanisms. Intravenous immunoglobulin has been established as the first-choice treatment for CIDP. Other treatments, including corticosteroid and plasma exchange are also applicable [3]. In recent years, autoantibodies targeting node of Ranvier proteins such as contactin-1 (CNTN1), contactin-2 (CNTN2), contactin-associated protein 1 (Caspr1), neurofascin 155 (NF155), and neurofascin 186 (NF186) have been detected in a small subset of patients with CIDP, which disrupt axoglial junctions at nodes or paranodes [4C6]. However, these antibodies against the node of Ranvier proteins are rare [7]. To our knowledge, no cases of CIDP with anti-Caspr1 have been previously reported in Chinese patients. Case presentation We present the case of a 66-year-old Chinese male patient with no previous relevant history or family history of neurological disease. He initially noticed numbness of the feet and weakness of the legs. Two?months later, the numbness spread to his thigh root, followed by weakness and numbness of his hands. Subsequently, he presented with gait ataxia and distal limb numbness. Therefore, he went to a local hospital for help. He showed mild facial bilateral paralysis. As his symptoms worsened, it was difficult for him to walk without assistance. Clinical examination showed that muscle weakness and sensory disturbance were observed in the distal parts of all limbs. In a manual muscle strength test, his upper limb muscle strength was grade 4 and lower limb muscle strength WIKI4 was grade 3. Deep tendon reflexes had disappeared in all limbs and no muscle atrophy was observed. No other abnormalities were found in the patients cranial nerves or autonomic nervous system. A head computerized tomography (CT)-scan was normal. He then underwent a lumbar puncture, which revealed albuminocytological dissociation, with protein concentration of 2.78?g/L and 2?cells?/l. Electromyography showed that sensory nerve conduction was prolonged in WIKI4 the upper and lower limbs, while motor nerve conduction and WIKI4 F-wave latency was prolonged in the upper limbs and disappeared in the lower limbs. Lumbar spine magnetic resonance imaging (MRI) showed mild herniated disc at lumbar segments 4 and 5 (L4CL5) and lumbar segment 5 and sacral segment 1 (L5CS1). Cervical spine MRI showed moderate herniated disc at cervical segment 3C6 (C3CC6). The thoraxCabdomenCpelvis CT scan detected no malignancy. A biochemical examination revealed no abnormal findings, with the exception of low hemoglobin (124?g/L), low albumin (30.4?g/L), high cholesterol (7.13?mmol/L), and high D-Dimer (1.48?mg/l). The results of screening assessments for human immunodeficiency virus, syphilis reaction, antineutrophil cytoplasmic antibody (ANCA), antinuclear antibody (ANA), common cancer markers, and lead level were unfavorable. The patients levels of creatine kinase and vitamins B1, B12, and E were normal. Other normal or unfavorable antibody assessments included myelin basic protein (MBP), myelin oligodendrocyte glycoprotein (MOG), aquaporin-4 (AQP4), antibodies associated with paraneoplastic neurological syndromes (PNS), and antiganglioside complex antibody profiles. He WIKI4 was suspected as CIDP and treated with intravenous immunoglobulin (0.4?g/kg/day for five consecutive days) and prednisone tablets 40?mg daily. The symptoms got worse after 1?month of therapy. The patient was then admitted to our hospital. He complained that sensory symptoms of numbness were more prominent than his motor weakness. Physical examination revealed bilateral periphery facial paralysis, decreased temperature of the limb extremities, reduced pinprick and vibration sense, absent reflexes of both the upper.