A 79-year-old woman without any cerebral hernia symptoms was hospitalized with hyponatremia. After syndrome of inappropriate antidiuretic hormone induced by drugs was diagnosed and water restriction implemented, the patient became comatose during overcorrection caused by the generation of a large volume of electrolyte-free urine. Once the serum sodium concentration was immediately relowered by the administration of desmopressin and 5% glucose solution, the patient's level of consciousness improved dramatically without osmotic demyelination syndrome (ODS) developing. This outcome suggests that, similar to the findings in rat models, relowering the serum sodium concentration as early as possible to counter a disturbance of consciousness during the overcorrection of hyponatremia prevents ODS.

We herein report a case of a consciousness disorder that was induced by the syndrome of inappropriate antidiuretic hormone secretion following cisplatin (CDDP) and 5 -fluorouracil (5-FU) chemotherapy in a patient with tongue cancer. A 72- year-old woman complained of tongue pain and was admitted to our hospital for neoadjuvant chemotherapy, under a diagnosis of tongue squamous cell carcinoma (T4aN2bM0). She was treated with CDDP and 5-FU. On the second day after administration, she complained of nausea and anorexia, and on the third day, she showed impaired consciousness. Laboratory studies revealed that the patient had a serum sodium concentration 112mEq/L, and no dehydration was noted. The patient was diagnosed with SIADH, using the appropriate diagnostic criteria based on serum and urine hypoosmolality. We subsequently discontinued chemotherapy and initiated fluid restriction and sodium supplements. Two days after this treatment, her consciousness level improved, and on the fifth day of treatment, laboratory studies revealed a serum sodium level of 134mEq/ L.

Syndrome of inappropriate antidiuretic hormone ADH release (SIADH) is a condition defined by the unsuppressed release of antidiuretic hormone (ADH) from the pituitary gland or nonpituitary sources or its continued action on vasopressin receptors. The condition was first detected in two lung cancer patients by William Schwartz and Frederic Bartter in 1967. They developed the classic Schwartz and Bartter criteria for the diagnosis of SIADH which has not changed. SIADH is characterized by impaired water excretion leading to hyponatremia with hypervolemia or euvolemia.

Hyponatremia is a potentially serious electrolyte abnormality observed in neuromyelitis optica spectrum disorders (NMOSDs), and its most common cause is syndrome of inappropriate antidiuretic hormone secretion (SIADH). Another potential cause of hyponatremia is cerebral salt-wasting syndrome (CSWS), although CSWS has not previously been reported in NMOSDs. Accurate and early differentiation between SIADH and CSWS is difficult. However, the two conditions have important implications for the selection of therapy. Here, we describe two patients with aquaporin-4 antibody (AQP4-Ab)-positive NMOSDs who developed hyponatremia as a result of CSWS and SIADH, respectively. Additionally, we review all previously reported studies of hyponatremia in patients with NMOSDs and propose several potential pathophysiological mechanisms of hyponatremia. In conclusion, NMOSDs accompanied by hyponatremia are not actually rare, but have previously been given little attention. Furthermore, SIADH should not be the only consideration, before the exclusion of rare but significant CSWS.

A 3-month-old intact male Prague ratter was presented to the emergency service for evaluation of progressive lethargy, weakness, coughing and labour breathing after an episode of resistance to oral deworming. The patient exhibited depression, increased respiratory effort and cyanosis at initial presentation. Results of first diagnostic work-up (complete blood cell count, biochemistry panel and thoracic x-rays) were all consistent with aspiration pneumonia. The puppy was initially treated with balanced isotonic crystalloids, broad spectrum antibiotics, nebulization with thoracic coupage and was transferred to an infant incubator with a sustained FiO2 of 40-50%. Twenty-four hours after ICU admission the patient's condition suffered a worsening and the dog was orthopneic, severely depressed with episodes of intermittent dysphoria and seizuring. New thoracic radiographs and several samples of blood and urine were collected to go further in the diagnostic workup revealing severe hyponatremia, severe plasma hypotonicity, high natriuresis and metabolic acidosis with a worsening of the radiological pulmonary pattern. Based on these new clinical findings a diagnosis of SIADH was established. Emergency treatment with hypertonic 3% saline solution and loop diuretics was started like a sodium supplement and to inhibit water resorption in renal tubules, thus reducing the volume overload. The goal of this treatment was to achieve a progressive and controlled increase of plasma sodium concentration and promoting the excretion of positive body water imbalance. The patient's condition improved clinically over the following days, treatment was progressively discontinued and the dog was discharged 7 days after admission. To the author's knowledge this is the first report of a puppy younger than 12 weeks with respiratory distress developing SIADH associated to aspiration pneumonia.