RESUMO
We report a 73-year-old man who presented symptoms of low back pain and SIADH followed by weakness of all four limbs and sensory disturbance of the lower legs 2 month after the first symptoms. He was referred to our department because of the evolution of weakness. Neurological examination on admission revealed weakness of the arms and legs, areflexia, and hypoesthesia of the lower legs. The straight leg raising test induced prominent radiating pain bilaterally. The level of sodium was 114 mEq/l, the plasma osmolality was 239 mOsm/kg, and the level of plasma antidiuretic hormone was 3.45 pg/ml. Other blood chemical values were unremarkable. The urine osmolality was 527 mOsm/kg. T1-weighted MR image with gadolinium showed thickening and enhancement of the nerve root. Nerve conduction study revealed compromised conduction with demyelinating features, and somatosensory evoked potential study could not show any potentials. He was diagnosed as having CIDP complicating with SIADH. An association between SIADH and AIDP has been much reported previously. To our knowledge, however, there has been no report of SIADH complicating with CIDP.
