Osmotic demyelination syndrome: novel risk factors and proposed pathophysiology

[Consensus recommendations on the diagnosis and treatment of hyponatremia from the Austrian Society for Nephrology 2024]

Hyponatremia is a disorder of water homeostasis. Water balance is maintained by the collaboration of renal function and cerebral structures, which regulate thirst mechanisms and secretion of the antidiuretic hormone. Measurement of serum-osmolality, urine osmolality and urine-sodium concentration help to diagnose the different reasons for hyponatremia. Hyponatremia induces cerebral edema and might lead to severe neurological symptoms, which need acute therapy. Also, mild forms of hyponatremia should be treated causally, or at least symptomatically. An inadequate fast increase of the serum sodium level should be avoided, because it raises the risk of cerebral osmotic demyelination. Basic pathophysiological knowledge is necessary to identify the different reasons for hyponatremia which need different therapeutic procedures.

Severe osmotic demyelination syndrome with cortical involvement in the context of severe hyponatremia and central diabetes insipidus: an uncommon presentation of an unusual combination

BACKGROUND

Osmotic demyelination syndrome (ODS) with cerebral cortical involvement is a rare complication of severe hyponatremia correction. Careful management of hyponatremia is crucial, particularly in patients with risk factors, such as alcohol use disorder and diabetes insipidus.

CASE

A patient in his 40s with a history of alcohol use disorder and central diabetes insipidus developed ODS after a 24 mEq/L osmolar increase during the treatment of hyponatremia. The patient's condition progressed into locked-in syndrome and then improved to spastic tetraparesis after cortical basal ganglia ODS improved.

DISCUSSION

The differential diagnosis of cortical demyelination includes laminar cortical necrosis, being the interpretation of Apparent Diffusion Coefficient (ADC) MRI sequence is a useful tool.This case underscores the need to investigate and improve diagnosis and treatment strategies in patients with ODS. It also emphasises the significance of careful hyponatremia correction and frequent monitoring, particularly in patients with known risk factors for ODS.

A Case of Alcohol Withdrawal-Induced Central and Extrapontine Myelinolysis

A 40-year-old female with a history of chronic alcohol use disorder presented with an acute intractable left-sided headache for three days and progressively worsening unsteady gait requiring a wheelchair to ambulate. The patient had a history of chronic alcoholism since 2019 but reported abstinence since September 2021. One month after quitting alcohol, she experienced a sudden deterioration in bilateral extremity neuropathy, forgetfulness, difficulty writing, and severe mood swings, which continued to worsen until her presentation in July 2022. Laboratory tests, including complete blood count and electrolyte levels, were within normal ranges. A previous MRI performed during the investigation for alcoholic neuropathy a few months before she quit drinking showed no abnormalities. However, a subsequent MRI during work-up for the current acute symptoms revealed significant signal abnormalities involving the central pons, bilateral cerebral peduncles, and medullary pyramids, consistent with chronic central pontine myelinolysis (CPM) with extrapontine myelinolysis (EPM) extending into the peduncles. The patient received treatment with folate and multivitamins and was scheduled for outpatient follow-up with physical therapy for rehabilitation. This case highlights CPM as a consequence of alcohol withdrawal and emphasizes the importance of timely diagnosis and appropriate management in such patients.

Osmotic Demyelination After Rapid Correction of Hyperosmolar Hyperglycemia

Osmotic demyelination syndrome (ODS) is seen due to an overt rise in serum osmolality, most often during rapid correction of chronic hyponatremia. We present the case of a 52-year-old patient who presented with polydipsia, polyuria, and elevated blood glucose with rapid correction of glucose levels under five hours and developed dysarthria, left-sided neglect, and unresponsiveness to light touch and pain in the left extremities on the second day of hospitalization. MRI revealed restricted diffusion in the central pons, extending into extrapontine areas suggestive of ODS. Our case highlights the importance of cautious correction of serum hyperglycemia and monitoring serum sodium levels in patients with a hyperosmolar hyperglycemic state (HHS).

Administration of 3% Sodium Chloride and Local Infusion Reactions

Three-percent sodium chloride (3% NaCl) is a hyperosmolar agent used to treat hyponatremic encephalopathy or other cases of increased intracranial pressure. A barrier to the use of 3% NaCl is the perceived risk of local infusion reactions when administered through a peripheral vein. We sought to evaluate reports of local infusion reactions associated with 3% NaCl over a 10-year period throughout a large healthcare system. A query was conducted through the Risk Master database to determine if there were any local infusion reactions associated with peripheral 3% NaCl administration throughout the entire UPMC health system, which consists of 40 hospitals with 8400 licensed beds, over a 10-year time period from 14 May 2010 to 14 May 2020. Search terms included infiltrations, extravasations, phlebitis, IV site issues, and IV solutions. There were 23,714 non-chemotherapeutic and non-contrast-associated intravenous events, of which 4678 (19.7%) were at UPMC Children’s Hospital. A total of 2306 patients received 3% NaCl, of whom 836 (35.8%) were at UPMC Children’s Hospital. There were no reported local infusion reactions with 3% NaCl. There were no reported local infusion reaction events associated with 3% NaCl in a large healthcare system over a 10-year period. This suggests that 3% NaCl can be safely administered through a peripheral IV or central venous catheter.