A 66-year old male was admitted with a history of 3-years bradykinesia and 1-month myoclonus at right lower limb.3 years ago, this patient gradually presented with increased muscle tone, unsteady gait, dizziness, frequent falls and sleep related snoring. He had a history of alcohol consumption with average 1500ml beer per day, which was considered cause of symptoms above by he and his family. One month ago, this patient developed symptoms of myoclonus at right lower limb and migrating physical pain all over his body. He was admitted inpatient in another hospital and diagnosed with Parkinson Disease. Madopar was prescrbed with 125mg, 1 hour before 3 meals. His serum sodium at discharge was 127 mmol/L (normal range:135-145mmol/L). Medopar was discontinued 1 week later due to subtle effect and serum sodium was not repeated thereafter. He eventually presented to our hospital and was admitted to inpatient department of neurology. He denied history of smoking or other diseases.
Neurological examination at that time revealed: sober mind, bradykinesia, increased muscle tone, unsteady gait, frequent right lower limb myoclonus, dysphagia, laryngeal stridor during sleep, frequent urination, urgent urination, constipation, hyper-reflexia in the lower limbs, positive bilateral Babinski and Hoffman signs. Other findings included: positive orthostatic hypotension (30mm Hg decrease in systolic blood pressure within 1 minute after Standing). T2-weighted MRI showed vertical hyperintensity with hot cross bun sign in the pon and putamen slit in right dorso-lateral putamen. Electromyography of the anus indicated neurogenic bladder. Post-void residual volume (PRV) was 229ml.
Based on the patient's clinical presentation, bradykinesia, increased muscle tone, poor response to madopar, and dramatic autonomic dysfunction, such as orthostatic hypotension (systolic blood pressure drop of 30 mmHg within 1 minute after standing) and increased PRV. Cranial T2-weighted images showed vertical hyperintensity with hot cross bun sign in the pon and putamen slit in the right dorso-lateral putamen. This patient was diagnosed with MSA [9, 10].
His serum sodium was tested at admission, which was 121.6mmol/L. 30mg duloxetine was prescribed to alleviate migrating physical pain. One day later, the patient suddenly had high fever, ranging between 38.0-39.5℃, without sweating or chilling despite repeated antipyretic treatment. Pulmonary CT, abdominal CT and blood / urinary tests were largely unrevealing and only showed mild urinary tract infection (WBC:13.5 / HP). Meanwhile, his serum sodium further declined from 121.6 to 117 mmol/L as shown in Fig. 2, although extra oral sodium supplement was prescribed. Concomitant 24-hour urinary sodium was 444.5mmol, plasma osmolarity was 269mOsm/kg, and urinary osmotic pressure was 404mOsm/k, which suggest excess circulating AVP. At the same time, the patient's blood sugar, blood potassium, T3, T4, cortisol and anterior pituitary hormone (Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), prolactin (PRL), growth hormone (GH), thyroid-stimulating hormone (TSH) growth hormone (GH)) was all within normal range. Cerebral salt wasting syndrome was not considered since no general dehydration was observed, and water restriction didn’t worsen symptoms [11, 12]. This patient was diagnosed with SIADH.[13].
Anti-inflammatory therapy didn’t improve increased body temperature or decreased blood sodium. After duloxetine was withdrawn, his body temperature gradually returned to normal but eventually increased to 38℃ due to pulmonary infection shown in Fig. 3. His blood sodium increased significantly shown in Fig. 2. Meanwhile, he began to sweat on both hands and feet. As pulmonary infection worsened, deep sputum aspiration was performed, which in turn caused tracheal spasm and further decreased blood oxygen concentration. This patient eventually died of respiratory and cardiac arrest soon after endotracheal intubation.