Sjögren syndrome presenting with encephalopathy mimicking Creutzfeldt–Jakob disease

A 61-year-old man developed subacute progressive dementia, general fatigue, a tonic–clonic seizure, and a decreased level of consciousness. He had a past history of chronic hepatitis type C and was diagnosed as having hepatic encephalopathy due to hyperammonemia. His level of consciousness did not improve even though the serum ammonia level improved. In addition, he had repeated general myoclonic seizures. Head MRI (diffusion-weighted imaging) showed high signal intensities in the right thalamus and the cerebral cortices in the frontal, temporal and parietal lobes (predominantly on the right side). An electroencephalogram (EEG) showed periodic lateralized epileptic discharges (PLEDs). Cerebrospinal fluid analysis revealed high total tau protein and 14-3-3 protein levels. This case was diagnosed as Creutzfeldt–Jakob disease (CJD) based on these clinical data. However, the patient gradually improved without specific treatment. The differential diagnosis was reconsidered, and an increased erythrocyte sedimentation rate and positive serum anti-SS-A and anti-SS-B antibodies were noted. A diagnosis of Sjögren syndrome (SjS) was finally made based on a biopsy of a minor salivary gland showing infiltration of lymphocytes around the gland ducts. Steroid therapy (prednisolone 40 mg/day orally) was given, and his clinical condition improved. The lesions on the head MRI decreased, and the EEG findings normalized. This case suggests that SjS has a wide spectrum, including neurological disorders, and that SjS should be considered in the differential diagnosis of CJD.