Osmotic Demyelinating Syndrome

ABSTRACT. This article discusses the clinical cases of rare and difficult to diagnose brain damage — osmotic demyelinating syndrome (ODS). ODS is a lifethreatening condition, manifested by acute demyelination of the headbrain on the background of water-electrolyte disturbances,usually associated with fast management of hyponatremia. Within the framework of ODS, central pontine myelinolysis (CPM) and extra-pontine myelinolysis (EPM) are observed, which are accompanied by acute demyelination in the pons and white matter of the cerebral hemispheres, respectively. In 60%, CPM combine with EPM. The main reason for the development of ODS is a violation of water-electrolyte metabolism associated with alcohol abuse, chronic hepatic and/or renal failure, diabetes mellitus, Sheehan syndrome, polydipsia, condition after the removal of pituitary adenoma, bulimia, immunodeficiency syndrome. Today, the diagnosis of ODS is based on magnetic resonance imaging of the brain. The article indicates the main causes of the disease, clinical features, methods of diagnosis and treatment, as well as the outcomes of the disease.

Diagnosis and Management of Sodium Disorders in the Neurosurgical Patient

Sodium disorders are the most common electrolyte abnormality among hospitalized patients and even more common in the neurosurgical patient population. Timely diagnosis and careful correction of serum sodium is an essential skill for the neurosurgical hospitalist and may greatly mitigate the risk of significant harm to the patient. Water dysregulation is the primary feature of sodium abnormalities and may manifest as hyponatremia due to syndrome of inappropriate antidiuretic hormone (SIADH) secretion or hypernatremia due to central diabetes insipidus (DI). Therapy for the correction of serum sodium must take into consideration the etiology of dysregulation, unique risks associated with different neurologic pathologies, and the risk of osmotic fluid shift associated with fluctuations in serum sodium. Rapidly correcting sodium levels may lead to a variety of unintended sequelae, including osmotic demyelinating syndrome (ODS), cerebral edema, seizure, pulmonary edema, and death. Since neurosurgical patients are at elevated risk for severe morbidity due to osmotic fluid shift, it is crucial that neurosurgical hospitalists have a firm understanding of water and sodium pathophysiology, expertise in the diagnosis and treatment of sodium abnormalities, and nuanced appreciation for the risks and features unique to neurosurgical diseases. This chapter outlines the most common etiologies of sodium disorders in the neurosurgical patient population and offers recommendations for their diagnosis and treatment. Hyponatremia due to hypovolemia, cerebral salt wasting (CSW), SIADH, and adrenal insufficiency (AI) will be highlighted first, followed by hypernatremia due to free water deficit in the setting of central DI and inadequate oral fluid intake.

Multiple Electrolyte and Metabolic Emergencies in a Single Patient

While some electrolyte disturbances are immediately life-threatening and must be emergently treated, others may be delayed without immediate adverse consequences. We discuss a patient with alcoholism and diabetes mellitus type 2 who presented with volume depletion and multiple life-threatening electrolyte and metabolic derangements including severe hyponatremia (serum sodium concentration [SNa] 107 mEq/L), hypophosphatemia (“undetectable,” <1.0 mg/dL), and hypokalemia (2.2 mEq/L), moderate diabetic ketoacidosis ([DKA], pH 7.21, serum anion gap [SAG] 37) and hypocalcemia (ionized calcium 4.0 mg/dL), mild hypomagnesemia (1.6 mg/dL), and electrocardiogram with prolonged QTc. Following two liters of normal saline and associated increase in SNa by 4 mEq/L and serum osmolality by 2.4 mosm/Kg, renal service was consulted. We were challenged with minimizing the correction of SNa (or effective serum osmolality) to avoid the osmotic demyelinating syndrome while replacing volume, potassium, phosphorus, calcium, and magnesium and concurrently treating DKA. Our management plan was further complicated by an episode of significant aquaresis. A stepwise approach was strategized to prioritize and correct all disturbances with considerations that the treatment of one condition could affect or directly worsen another. The current case demonstrates that a thorough understanding of electrolyte physiology is required in managing complex electrolyte disturbances to avoid disastrous outcomes.

Relowering of Serum Na for Osmotic Demyelinating Syndrome

We report a case in whom slow correction of hyponatremia (5 mmol/day for 3 days) induced central pontine myelinolysis (CPM). After the diagnosis was confirmed by imaging, we started to relower serum Na that completely recovered the sign and symptoms of CPM. Rapid correction of serum sodium is known to be associated with CPM. However, it may occur even after slow correction of hyponatremia. Currently, there is no standard therapy for CPM other than supportive therapy. Other therapy includes sterioid, plasmaphresis and IVIG, but these therapies have not been shown to be particularly effective. The pathophysiology of CPM is related to a relative dehydration of the brain during the correction of hyponatremia, resulting in cell death and demyelination, therefore gentle rehydration with lowering serum sodium may not be an unreasonable therapy. The present case provides supportive evidence that reinduction of hyponatremia is effective in treating CPM if started immediately after the diagnosis is suggested. The present case tells us that severe chronic hyponatremia must be managed with extreme care especially in patients with chronic debilitating illness and that relowering serum Na is a treatment of choice when CPM is suggested.