Normonatremic osmotic demyelination in the setting of acquired immune deficiency syndrome and malnutrition: case report and literature review

Osmotic Demyelination Syndrome in a High-Risk Patient Despite Cautious Correction of Hyponatremia

Hyponatremia is a common electrolyte disorder requiring careful management to prevent severe complications. Osmotic demyelination syndrome (ODS) is a serious neurological disorder that can develop from rapid correction of hyponatremia. Herein, is a description of the case of a 61-year-old man with multiple risk factors, including alcoholism, hypokalemia, malnutrition, and alcoholic liver cirrhosis, who developed ODS despite adherence to the recommended correction rate for hyponatremia. The patient presented to the emergency department with generalized weakness, gait disturbance, and decreased muscle strength. Initial laboratory investigations revealed severe hyponatremia, hypokalemia, and dehydration. The patient was treated with cautious correction of the hyponatremia below 8 mmol/L per day. However, on the seventh hospital day, he developed tremors, rigidity, and decreased consciousness and was diagnosed with osmotic demyelination syndrome. Despite receiving general supportive care, desmopressin, and dextrose 5% in water to reduce the serum sodium levels, the patient did not show significant improvement and was transferred to a nursing home for long-term conservative care on day 35 of hospitalization. This case report highlights the challenges associated with the diagnosis and management of osmotic demyelination syndrome and the importance of identifying patients at high risk of developing this neurological disorder.

Thalamic Neuron Resilience during Osmotic Demyelination Syndrome (ODS) Is Revealed by Primary Cilium Outgrowth and ADP-ribosylation factor-like protein 13B Labeling in Axon Initial Segment

A murine osmotic demyelinating syndrome (ODS) model was developed through chronic hyponatremia, induced by desmopressin subcutaneous implants, followed by precipitous sodium restoration. The thalamic ventral posterolateral (VPL) and ventral posteromedial (VPM) relay nuclei were the most demyelinated regions where neuroglial damage could be evidenced without immune response. This report showed that following chronic hyponatremia, 12 h and 48 h time lapses after rebalancing osmolarity, amid the ODS-degraded outskirts, some resilient neuronal cell bodies built up primary cilium and axon hillock regions that extended into axon initial segments (AIS) where ADP-ribosylation factor-like protein 13B (ARL13B)-immunolabeled rod-like shape content was revealed. These AIS-labeled shaft lengths appeared proportional with the distance of neuronal cell bodies away from the ODS damaged epicenter and time lapses after correction of hyponatremia. Fine structure examination verified these neuron abundant transcriptions and translation regions marked by the ARL13B labeling associated with cell neurotubules and their complex cytoskeletal macromolecular architecture. This necessitated energetic transport to organize and restore those AIS away from the damaged ODS core demyelinated zone in the murine model. These labeled structures could substantiate how thalamic neuron resilience occurred as possible steps of a healing course out of ODS.

Pontine Neoplasm or Myelinolysis Despite Normal Sodium Levels

An elderly woman was transferred for biopsy of a pontine lesion. Her condition, including gait disturbances, truncal ataxia, and dysarthria-presumed to be due to severe alcohol abuse-had deteriorated during treatment of ambulatory-acquired pneumonia. No electrolyte abnormalities were noted during hospitalization. However, the neuroimaging findings were in line with central pontine myelinolysis, typically sparing the peripheral pontine fibers. Although extremely rare, pontine myelinolysis can occur in the presence of normal electrolyte levels. Thus, imaging findings should not be misinterpreted as pontine neoplasms, and patients should not undergo stereotactic biopsy-a procedure that could result in disastrous morbidity.

Incidence of osmotic demyelination syndrome in Sweden: A nationwide study

OBJECTIVE

To report the incidence rate of osmotic demyelination syndrome (ODS), associated risk factors, treatment, and long-term outcomes in a nationwide cohort.

METHODS

We conducted a retrospective study of individuals diagnosed with central pontine myelinolysis (ICD-10 code G37.2) in the Swedish National Patient Register during 1997-2011.

RESULTS

During the study period, we identified 83 individuals with ODS, 47 women and 36 men. Median age at diagnosis was 55 years. The incidence rate of ODS for the entire study period was 0.611 (95% CI: 0.490-0.754) per million person-years and increased during the study period from 0.271 (95% CI: 0.147-0.460) in 1997-2001 to 0.945 (95% CI: 0.677-1.234) individuals per million person-years in 2007-2011. Most cases (86.7%) were hyponatremic with a median sodium level at admission of 104 mmol/L. All hyponatremic cases were chronic. The cause of hyponatremia was multifactorial, including drugs (56.9%), polydipsia (31.9%), and vomiting or diarrhea (41.7%). A majority of patients (69.9%) were alcoholics. Hyponatremic patients were predominantly treated with isotonic saline (93.1%) and only 4.2% with hypotonic fluids. The median correction rate was 0.72 mmol/L/h. Only six patients were corrected in accordance with national guidelines (≤8 mmol/L/24/h). At three months, 7.2% had died and 60.2% were functionally independent (modified Rankin Scale 0-2).

INTERPRETATION

We found an increasing incidence during the study period, which could partly be explained by increased access to magnetic resonance imaging. ODS occurs predominantly in patients with extreme chronic hyponatremia which is corrected too fast with isotonic saline. Most patients survived and became functionally independent.