Central pontine myelinolysis: a preventable complication of hyponatremia correction

Full Text

INTRODUCTION

Osmotic demyelination syndrome (ODS) is an acute disorder characterized by non-inflammatory demyelination in specific brain regions in the setting of water-electrolyte disturbances, most commonly related to rapid correction of hyponatremia [1, 2]. Two main forms are distinguished: central pontine myelinolysis, when the demyelinating lesion is located in the pons, and extrapontine myelinolysis, when demyelinating foci are observed in the cerebral peduncles, thalami, and corpus callosum. In about 60% of cases central pontine myelinolysis and extrapontine myelinolysis coexist [3].

Epidemiology

The syndrome was first described by R. Adams et al. in 1959 in four malnourished patients with alcoholism who presented with pseudobulbar syndrome and tetraplegia and were found at autopsy to have demyelination in the pons [4]. As early as the 1970s the development of this syndrome was linked to rapid correction of hyponatremia [3]. Before the advent of magnetic resonance imaging (MRI) ODS was considered extremely rare. A recent meta-analysis of cohort studies that included neuroimaging data estimated the frequency of ODS to be 0.23% among all patients with hyponatremia [5], whereas in individual cohorts of intensive care patients with water-electrolyte disturbances the frequency of ODS may reach 2.5% [6].

Etiopathogenesis

The main cause of central pontine myelinolysis is correction of chronic hyponatremia or other electrolyte disturbances observed in such conditions as alcoholism with malnutrition, liver disease, decompensated diabetes mellitus, pituitary adenoma, Sheehan’s syndrome, anorexia nervosa, hyperemesis gravidarum, severe burns, nutritional deficiency or, conversely, bulimia, urea cycle disorders, and the use of diuretics or psychotropic drugs [7]. In rare cases central pontine myelinolysis develops as a complication after liver transplantation [1–3]. In some patients severe viral infections, systemic lupus erythematosus, immunodeficiency states, and COVID-19 act as predisposing factors for osmotic demyelination [8, 9].

According to current concepts, the risk of ODS is high when serum sodium falls below 120 mmol/L for more than 48 hours and is then corrected at a rate exceeding 12 mmol/L per day. In chronic hyponatremia astrocytes and oligodendrocytes adapt to the decreased plasma osmolality by actively extruding intracellular osmolytes: amino acids (glutamate, taurine, glycine), polyols (myo-inositol), and ions (Na+, K+, Cl-). When sodium concentration is rapidly corrected, extracellular osmolality rises sharply, whereas reacquisition of organic osmolytes is substantially delayed, which creates a pathological osmotic gradient that leads to cellular dehydration and apoptosis of astrocytes and oligodendrocytes. The central portion of the pons is particularly vulnerable to osmotic injury because of the dense intermingling of gray and white matter with an extremely high concentration of myelinated tracts in a relatively small area [10]. An immune component is also involved in the pathogenesis: osmotic stress may trigger the production of myelinotoxic factors that, penetrating through a damaged blood–brain barrier, aggravate demyelination and elicit an immune response against myelin antigens. The potential efficacy of plasmapheresis in the treatment of ODS is explained by its impact on these mechanisms [11, 12]. Recent reports have described cases of ODS not associated with hyponatremia: in children with hypernatremia and its rapid correction, in hyperglycemic hyperosmolar states [13], in patients with chronic alcoholism after alcohol withdrawal in the presence of normonatremia, as well as a complication of refeeding syndrome [14].

The pathological basis of ODS is demyelination of axons and death of oligodendrocytes and astrocytes in the central pons. It is believed that irreversible axonal damage and neuronal death do not usually occur; therefore, in most cases the motor deficits associated with ODS are potentially reversible [3, 10].

Clinical presentation

The main clinical manifestation of central pontine myelinolysis is pseudobulbar syndrome, including dysphagia, dysphonia, and dysarthria on the background of central tetraparesis. With further progression, central tetraplegia with a “locked-in” syndrome may develop [3, 6]. Motor disturbances in ODS present as increased muscle tone, hyperreflexia, and pathological oral and spinal automatisms. When demyelination extends to extrapyramidal structures of the midbrain and diencephalon, hyperkinetic movement disorders (ataxia, parkinsonism, dystonia) may occur. Less common symptoms include vertical or horizontal gaze palsy, convergent strabismus, and pontine alternating syndromes (Millard–Gubler, Foville, Gasperini syndromes). A characteristic feature of ODS is a biphasic course with a “lucid interval”: an initial deterioration due to electrolyte disturbances with encephalopathy, followed by transient improvement after correction, and then, after 2–5 days, a second deterioration with development of brainstem and/or subcortical symptoms up to tetraplegia and coma, which markedly worsens the prognosis [9, 15].

Diagnosis

ODS should be suspected in the presence of the above neurological symptoms in combination with a history of water-electrolyte disturbances and infusion therapy. The diagnosis is confirmed by magnetic resonance imaging (MRI), which reveals characteristic hyperintense demyelinating lesions on diffusion-weighted imaging (DWI), T2-weighted images (T2WI), and FLAIR. In extrapontine myelinolysis the lesions are usually symmetric and ovoid in the supratentorial white matter; in central pontine myelinolysis they have a trident- or “butterfly-wing” shape in the pons, reflecting predominant involvement of transverse pontine fibers with relative sparing of vertical tracts [16, 17]. MRI manifestations of central pontine myelinolysis are stage-dependent. In the acute stage the main changes are seen on DWI as restricted diffusion (signal hyperintensity on DWI and low signal on the apparent diffusion coefficient [ADC] map). T2WI in the acute phase may be normal or show only mildly increased signal. In the subacute and chronic stages there is a pronounced T2-hyperintense signal in the affected regions, whereas diffusion restriction on DWI is absent.

Treatment

There is no specific treatment for ODS. Management is mainly supportive and aimed at stabilizing the patient’s general condition, restoring lost skills and functions, and preventing complications. Patients require physiotherapy and speech therapy. Drug treatment of myelinolysis is focused primarily on careful correction of water-electrolyte imbalance in combination with neurometabolic and antioxidant therapy. Antiseizure medications are prescribed in the presence of epileptic seizures. Approximately 60% of central pontine myelinolysis cases end in recovery with minimal neurological deficit; in the remaining patients residual manifestations depend on the extent of brain involvement. Adverse outcomes include paralysis, paresis, speech disorders, and severe cognitive impairment. Compared with historical data, the mortality associated with ODS has substantially decreased due to improvement of medical care protocols and currently is about 8.8% [5].

The aim of this case report is to remind intensive care physicians and other specialists of osmotic demyelination as a serious complication of electrolyte disturbance correction and to discuss its frequency, diagnosis, treatment, and prevention.

CASE REPORT

Patient Information

A woman born in 1987, head of a private company, presented with complaints of unsteadiness while walking, weakness in the legs, hoarseness of voice, and choking on liquids. She denied alcohol abuse.

Anamnesis morbi. At the end of October 2023, in the context of a stressful situation, the patient noted loss of appetite and almost stopped eating; for one week she had daily vomiting of bile. 31.10.2023 the patient suddenly lost consciousness and experienced multiple convulsive seizures; she was urgently hospitalized by an ambulance team to the intensive care unit of an emergency city hospital with a diagnosis of “G40.9 Newly diagnosed epileptic syndrome, state after a series of seizures”. Examination revealed community-acquired, multisegmental destructive pneumonia (presumably of aspiration origin), encephalopathy of mixed etiology, multiple organ failure, secondary left ventricular myocardial injury, and water-electrolyte disturbances (hyponatremia, hypokalemia, hypochloremia). She received mechanical ventilation, antiseizure therapy, correction of electrolyte disturbances, and antibiotic therapy. The patient received tube feeding in the intensive care. Once her condition stabilized and her respiratory function improved, she was transferred to the medical ward, and tube feeding was replaced with oral feeding (no detailed data on refeeding is available). With stabilization of her condition and recovery of respiratory function, her general condition improved, she was transferred to the internal medicine department and subsequently, on 14.11.2023, discharged for outpatient treatment with a diagnosis of J18.1, community-acquired bilateral destructive multisegmental pneumonia, and a concurrent diagnosis of encephalopathy of complex genesis with seizure syndrome. According to the patient, she began to notice hoarseness and mild difficulty swallowing while she was still in the medical ward. Three days after discharge she noted progressive swallowing and speech disturbances, pronounced generalized weakness, and marked gait unsteadiness up to inability to walk independently, and 18.11.2023 was admitted to the neurology department of the Federal Research and Clinical Center of the FMBA of Russia (for details see the Timeline of disease progression on Fig. 1).

 

Fig. 1. Timeline of disease progression indicating key parameters of water-electrolyte balance and describing the main symptoms and events.

 

Examination findings

On admission the patient’s condition was of moderate severity. Level of consciousness: 15 points (Glasgow Coma Scale). Body temperature: 36.4 °C. Skin: dry, eczematous rash on the forearms and shins, multiple traces of falls (abrasions on the legs). Edema: moderate pedal edema. Respiratory system: status after bilateral pneumonia; no rales, no respiratory failure, respiratory rate 18/min. Cardiovascular system: no abnormalities; blood pressure 110/60 mmHg. Gastrointestinal tract: no abnormalities; urination intact.

Neurological status: Conscious, cooperative. No meningeal signs. Cognitive impairment and disinhibition were present, with reduced insight into her condition. Emotional lability was noted. Pupils and palpebral fissures were equal. Photoreactions were brisk, convergence was adequate. Face symmetric. Hearing intact. No nystagmus. Moderate dysphonia and dysphagia; the three-sip test was negative. Head turning and shoulder shrugging were full strength. Tongue in the midline. Tetraparesis: strength was symmetrically reduced in the arms and legs to 3/5. Muscle tone was increased in a pyramidal pattern. Tendon and periosteal reflexes were brisk and symmetric in the upper limbs, decreased and symmetric in the lower limbs. No extensor plantar responses were present at the time of examination. Superficial sensation was intact. Deep muscle sense in the feet was impaired. Coordination tests were performed with intention tremor and dysmetria bilaterally. The Romberg test showed unsteadiness. Walking was possible only with support or holding onto a wall or handrail. Sphincter control was preserved.

Speech therapist consultation. Speech status: dysphonia (moderate), dysphagia (mild), subtle dysarthric features, and impaired neurodynamic processes.

Admission diagnosis: G31.9 Encephalopathy of complex genesis (dysmetabolic, toxic? nutritional).

Laboratory investigations. According to the discharge documentation from the previous hospital, on admission there the patient had hyponatremia with serum sodium of 101.8 mmol/L; 12 hours after admission, on the background of infusion therapy, sodium was 109.8 mmol/L; after 24 hours it was 121.0 mmol/L (an increase of 19.2 mmol/L over the first 24 hours). Forty-eight hours after the initial hospitalization, sodium was 135.5 mmol/L. Serum potassium at the initial hospitalization was 1.72 mmol/L, 2.55 mmol/L, and 3.49 mmol/L on admission, after 24 and 48 hours, respectively. At the time of repeat hospitalization, serum sodium was 138 mmol/L and potassium 3.4 mmol/L.

Complete blood count: white blood cells 7.9×10⁹/L; red blood cells 3.3×10¹²/L; hemoglobin 117 g/L; hematocrit 34.4%; platelets 299×10⁹/L; leukocyte differential within normal limits; ESR (Westergren) 24 mm/h.

Urinalysis was unremarkable: no protein was detected in 24-hour urine; daily urine volume was 2.9 L.

Blood biochemistry: total protein 64 g/L; albumin 39 g/L; urea 3.2 mmol/L; uric acid 309.2 μmol/L; creatinine 56.2 μmol/L. Iron 11.1 μmol/L; transferrin saturation 18.42%; transferrin 2.35 g/L; LDH 200 U/L; CPK 44 U/L; GGT 129 U/L; AST 20 U/L; ALT 28 U/L; folic acid 2.13 ng/mL (reference: 3.5–17 ng/mL; moderate folate deficiency); glucose 5.39 mmol/L; CRP 6.5 mg/L (elevated); vitamin D 8.6 ng/mL (severe deficiency).

NT-proBNP 260.3 pg/mL (low probability of heart failure). Procalcitonin 0.119 ng/mL (low probability of sepsis).

Lipid profile, thyroid hormones (T3, T4, TSH), ACTH, D-dimer level, and a basic coagulation panel were within normal limits.

Instrumental investigations. Electrocardiography: accelerated atrial rhythm with heart rate 88–91 bpm, horizontal electrical axis, repolarization abnormalities in leads III and aVF in the form of inverted T waves, and an early repolarization pattern.

Ultrasound of the hepatobiliary system: ultrasound signs of diffuse changes in the liver and pancreas.

Brain magnetic resonance imaging: brain MRI was performed in three planes (T1-, T2-weighted, and FLAIR sequences). A single small lesion up to 2 mm, most likely of vascular origin, was seen in the right frontal lobe. In the central pons there was a pathological zone of high signal on T2WI, FLAIR, and DWI with a trident- or “butterfly-wing”-shaped configuration and no signal decrease on the ADC map, measuring 23×13×15 mm (Fig. 2). The absence of ADC hypointensity was consistent with the subacute stage of the disease. A 2-mm lesion was also noted in the right thalamus. Conclusion: MRI signs of pontine involvement; given the typical localization and shape of the lesion, the findings most likely correspond to osmotic demyelination syndrome (central pontine myelinolysis). Single small vascular-type lesions. Cyst of the left maxillary sinus.

 

Fig. 2. Brain magnetic resonance imaging of the patient on admission. T2-weighted image, axial view (а). FLAIR, axial view (b). FLAIR, coronal view (c). DWI (diffusion weighted imaging), b=1000, axial view (d). Osmotic demyelination in the central pons is seen as a hyperintense lesion with a “trident” or “butterfly wing” configuration (white arrows). MRI was performed on a 1.5 T Siemens scanner.

 

Electroencephalography: background activity consisted predominantly of alpha rhythm with smoothed zonal distribution and a frequency of 10–10.5 Hz. No paroxysmal activity or focal slowing of cortical rhythms was detected.

Differential diagnosis

The differential diagnosis included central pontine myelinolysis versus Wernicke’s encephalopathy (thiamine-deficiency encephalopathy), dysmetabolic encephalopathy, and acute cerebrovascular accident in the vertebrobasilar circulation. Wernicke’s encephalopathy was a plausible diagnosis in this patient because of the history of prolonged nutritional disturbances. However, against Wernicke’s encephalopathy were the absence of nystagmus and ophthalmoplegia, as well as the absence of typical MRI findings of thiamine-deficiency encephalopathy [18]. Given that the classic Wernicke triad is often incomplete, we considered thiamine deficiency as a possible concomitant metabolic factor; accordingly, thiamine was included in the treatment regimen. Dysmetabolic or toxic-nutritional encephalopathy was deemed unlikely because acute metabolic encephalopathies typically present on MRI with diffuse or multifocal, often bilateral changes involving the cortex, basal ganglia, thalami, or white matter, rather than isolated pontine involvement [19]. Impaired deep sensation, sensory ataxia, and diminished reflexes in the legs were initially interpreted as polyneuropathy; however, the inflammatory nature of the polyneuropathy was ruled out due to the absence of signs of systemic inflammation and ascending symptoms. Ischemic stroke in the territory of the perforating branches of the basilar artery may present with dysarthria, dysphagia, ataxia, pyramidal signs, pseudobulbar syndrome, and, in bilateral lesions, tetraparesis. Stroke can be differentiated from central pontine myelinolysis by its monophasic, acute onset, by clinico-radiological lateralization, and by MRI evidence of vertebrobasilar territory infarction.

Depending on the stage and severity of the clinical picture, central pontine myelinolysis may also need to be differentiated from multiple sclerosis, acute disseminated encephalomyelitis, autoimmune or infectious encephalitis, progressive multifocal leukoencephalopathy, cerebral vasculitis, pontine tumors, hypertensive encephalopathy/PRES, and mitochondrial encephalopathies [3].

In our patient several almost pathognomonic features supported the diagnosis of central pontine myelinolysis: severe initial hyponatremia (Na 101.8 mmol/L) with a rapid increase in sodium of 19.2 mmol/L during the first 24 hours and 33.7 mmol/L over 48 hours, which must be regarded as excessively rapid correction of hyponatremia [20]. Clinically, central pontine myelinolysis was suggested by the biphasic course with secondary deterioration two weeks after correction of electrolyte disturbances, as well as by brainstem-pyramidal signs in the form of dysphagia, dysphonia/dysarthria, tetraparesis, and ataxia. The diagnosis of central pontine myelinolysis was confirmed by MRI, which demonstrated symmetric involvement of the central pons with a trident/“butterfly-wing”-shaped hyperintense lesion on T2/FLAIR/DWI, corresponding to the typical pattern of osmotic demyelination [14–16].

Diagnosis

Final clinical diagnosis: G37.2 Central pontine myelinolysis. Tetraparesis. Vestibulo-atactic syndrome.

Treatment

To maintain fluid and electrolyte balance and prevent thiamine deficiency, infusion therapy with polyionic solutions (Sterofundin, 20 mL/kg/day, with monitoring of serum sodium levels) and thiamine hydrochloride (100 mg/day) was administered. For neuroprotection, the following were prescribed: ethylmethylhydroxypyridine succinate 4.0 mg IM, folic acid 1 mg 1 tablet in the morning, and pyridoxine hydrochloride 100 mg/day IM. To treat polyneuropathy syndrome, the following were prescribed: thioctic acid 600 mg/day IV drip; dexamethasone 8 mg/day IM; and ipidacrine 1.0 mg/day IM (for the first 3 days, until a clinical diagnosis was established; this therapy was subsequently discontinued). Due to severe cognitive impairment, memantine hydrochloride 10 mg (1 tablet) in the morning was empirically prescribed. Physical therapy: individualized therapeutic exercises with an instructor, kinesiotherapy, electrotherapy, and speech therapy massage.

Clinical course and outcome

After the treatment, marked positive dynamics were observed: muscle strength increased to 4–4.5/5 in the arms and to 4/5 in the legs; the severity of vestibulo-atactic symptoms decreased; speech and swallowing normalized; and cognitive and psycho-emotional status improved. The patient was discharged for outpatient rehabilitation.

One month after discharge she was seen again by a neurologist at the Federal Research and Clinical Center. Neurological symptoms had completely regressed; no cognitive impairment was detected on clinical examination, and her work capacity was fully restored.

Prognosis

The prognosis for life and recovery in this case was favorable.

DISCUSSION

Until recently, ODS was considered a rare disease; however, its detection rate has increased with the wider use of brain MRI and growing awareness of complications related to hyponatremia correction. Clinically, ODS is a heterogeneous disorder with a spectrum of courses ranging from asymptomatic or mildly symptomatic to rapidly progressive, fatal forms with development of a “locked-in” syndrome and a high risk of death. It is believed that the prognosis of the disease is not determined by the severity of clinical symptoms or by neuroimaging findings, but rather by the extent of the underlying electrolyte disturbances [3, 10, 15].

Regardless of the underlying disease, the development of ODS is invariably associated with water-electrolyte disturbances, and the true frequency of this serious complication may be quite high. In a large autopsy study conducted in 1981, central pontine myelinolysis was found in 37 out of 636 autopsies with histological examination of the brainstem, corresponding to a frequency of 5.8% in that cohort [21]. The most common underlying conditions in this series were malignant neoplasms (43%), chronic lung diseases (27%), and chronic renal failure requiring hemodialysis (14%). Retrospective analysis showed that electrolyte abnormalities were present in 78% of central pontine myelinolysis cases; significant fluctuations in blood gases and/or pH in 62%; hyper- or hyponatremia in 47%; marked hypoxemia in 12.5%; and hypokalemia in 9% [21]. Thus, the possibility of ODS should be considered in all intensive care patients with severe electrolyte disturbances.

In a retrospective cohort study from Sweden covering the period 1997–2016, 83 cases of ODS (47 women and 36 men, median age 55 years) were identified [2]. The overall incidence of ODS was 0.611 (95% CI: 0.490–0.754) per million person-years, with an increase from 0.271 (95% CI: 0.147–0.460) in 1997–2001 to 0.945 (95% CI: 0.677–1.234) in 2007–2011. In most cases (86.7%) ODS was associated with chronic hyponatremia and its correction; the median initial serum sodium concentration was 104 mmol/L. The main causes of hyponatremia were drug-induced (56.9%), polydipsia (31.9%), and eating disorders (41.7%). The majority of patients (69.9%) were alcohol-dependent. In 93.1% of ODS cases water-electrolyte disturbances had been corrected using isotonic saline. The median correction rate of hyponatremia was 0.72 mmol/L/h; however, only six ODS patients had received correction of hyponatremia in accordance with clinical guidelines (≤8 mmol/L per 24 hours). At 3-month follow-up, 7.2% of patients with ODS had died, and 60.2% were functionally independent [2].

In another cohort study from India (2015) that included 665 intensive care patients, ODS was diagnosed by neuroimaging in 17 patients (2.5%; 11 men and 6 women) with a median age of 32 years (range 12–78 years) [6]. A more recent U.S. cohort study (2021) analyzed 45 cases of ODS diagnosed on the basis of brain MRI in patients receiving intensive care [1]. The median age in that cohort was 48.4 years, and sex distribution was approximately equal. Liver disease was present in 27% of patients, alcoholism in 44%, and renal failure in 20%. Only 29% of ODS cases were attributable to rapid correction of hyponatremia; 29% of patients had other electrolyte disturbances. Six-month outcomes showed minimal neurological deficit or recovery in 60% of patients, whereas 16% died [1].

The most comprehensive modern source on ODS is a systematic review and meta-analysis published in 2024, which combined 11 cohort studies including a total of 26,710 hospitalized patients with hyponatremia [5]. Serum sodium levels across studies ranged from <116 to <130 mmol/L; rapid correction of hyponatremia was defined as an increase of >8–12 mmol/L per day. The meta-analysis showed that the overall frequency of ODS in the included studies was 0.23%. The rate of ODS in patients with rapid and slow correction of hyponatremia was 0.73% and 0.10%, respectively. Thus, rapid correction of hyponatremia was convincingly shown to be significantly associated with the development of ODS (OR 3.16; 95% CI 1.54–6.49; I²=27%). At the same time, the authors noted that in a certain proportion of patients ODS developed despite slow correction of sodium [5].

These cohort data suggest that the frequency of osmotic demyelination in intensive care patients with electrolyte disturbances is clearly higher in clinical centers where recommendations on the rate of hyponatremia correction are followed less strictly. The presence of clinical signs of pontine involvement is not obligatory, and asymptomatic forms of ODS have been described [22].

Most national guidelines recommend limiting the correction of hyponatremia to no more than 10 mmol/L during the first 24 hours and no more than 8 mmol/L during subsequent 24-hour periods until a serum sodium level of 130 mmol/L is reached [15]. It is important to emphasize that overly slow correction of severe hyponatremia is itself associated with an increased risk of death and longer stays in the intensive care unit [10]; therefore, in each case an individualized approach is required, with careful balancing of the risks of mortality and complications.

The Russian national guidelines on intensive care state that hyponatremia should be corrected at a rate not exceeding 1–2 mmol/L per hour and that correction should be stopped when serum sodium reaches 125–130 mmol/L [23]. An important addition to this recommendation concerns patients at high risk of osmotic demyelination (initial sodium <105 mmol/L, alcoholism, hypokalemia, malnutrition, or severe liver disease). In this group, the recommended rate of hyponatremia correction does not exceed 8 mmol/L during any 24-hour period, and correction should be stopped when serum sodium reaches 125 mmol/L [20]. In our opinion, this strategy should be followed in all patients with chronic hyponatremia.

CONCLUSION

Osmotic demyelination syndrome, manifesting as central pontine and extrapontine myelinolysis, is a serious complication of electrolyte disturbances, with a frequency of about 0.23% among intensive care patients but reaching 2.5% or more in certain cohorts. Prevention of ODS requires slow correction of chronic hyponatremia (not more than 1–2 mmol/L per hour and not more than 10 mmol/L in the first 24 hours and 8 mmol/L in subsequent 24-hour periods). Correction of chronic hyponatremia should be stopped when serum sodium reaches 125 mmol/L.

The present clinical case illustrates a classic form of central pontine myelinolysis with development of pseudobulbar symptoms and tetraparesis two weeks after excessively rapid correction of hyponatremia. Given the possible severe and, conversely, asymptomatic forms of central pontine myelinolysis, neurologists, intensive care physicians, and specialists in related fields must remain aware of this risk and correct electrolyte disturbances with utmost caution, in strict accordance with current clinical guidelines.

ADDITIONAL INFORMATION

Authors’ contributions: E.V. Shirshova, study concept, patient management, manuscript drafting and editing; I.V. Zakharchuk, patient management, manuscript drafting; E.O. Kontarova, A.V. Lugovoy, MRI acquisition and interpretation, figure preparation, manuscript editing; M.O. Shkap, figure preparation, manuscript editing; V.P. Baklaushev, manuscript drafting and editing.

Acknowledgments: The authors are grateful to the Head of the Radiology Department of the Federal Research and Clinical Center of the FMBA of Russia, V.N. Lesnyak, for expert assistance in obtaining and interpreting the neuroimaging data.

Consent for publication: The authors obtained the patient’s written informed consent to publish personal data in a scientific journal, including its electronic version (signed 2026 Jun 1). The scope of the published data was agreed upon with the patient.

Funding source: This work was supported by the Federal Medical-Biological Agency of Russia.

Disclosure of interests: The authors declare that there is no conflict of interest related to the description of this clinical case.

Statement of originality: The authors declare that this work is original and has not been previously published or submitted for publication elsewhere.

Data availability statement: The authors do not provide access to the data obtained in the course of preparation of this article, as these data represent confidential information from the patient’s medical records.

Generative AI: The authors used generative artificial intelligence (AI) when performing the literature search and systematization on the problem of osmotic demyelination syndrome (Perplexity Pro, www.perplexity.ai). The authors declare that all AI-generated information has been fully verified by the authors and is consistent with the current state of knowledge.

About the authors

Elena V. Shirshova

Federal Scientific and Clinical Center for Specialized Types of Medical Care and Medical Technologies

Author for correspondence.
Email: shirshova.ev@fnkc-fmba.ru
ORCID iD: 0000-0001-9193-0534
SPIN-code: 7491-0434

MD, PhD, Professor

Russian Federation, Moscow

Irina V. Zakharchuk

Federal Scientific and Clinical Center for Specialized Types of Medical Care and Medical Technologies

Email: zacharcuk.iv@fnkc-fmba.ru
ORCID iD: 0009-0003-6921-0145
Russian Federation, Moscow

Elena O. Kontarova

Federal Scientific and Clinical Center for Specialized Types of Medical Care and Medical Technologies

Email: kontarova@mai.ru
ORCID iD: 0000-0002-5550-7875
SPIN-code: 2889-2826

MD, PhD

Russian Federation, Moscow

Alexander V. Lugovoy

Federal Scientific and Clinical Center for Specialized Types of Medical Care and Medical Technologies

Email: a-lugovoy@list.ru
ORCID iD: 0009-0000-0914-1350
Russian Federation, Moscow

Matthew O. Shkap

Federal Center of Brain Research and Neurotechnologies

Email: matshk63@gmail.com
ORCID iD: 0009-0009-2936-7029
SPIN-code: 2616-6456
Russian Federation, Moscow

Vladimir P. Baklaushev

Federal Scientific and Clinical Center for Specialized Types of Medical Care and Medical Technologies; Federal Center of Brain Research and Neurotechnologies; Pulmonology Scientific Research Institute

Email: baklaushev@fccps.ru
ORCID iD: 0000-0003-1039-4245
SPIN-code: 3968-2971

MD, PhD, Assistant Professor, Professor of the Russian Academy of Sciences

Russian Federation, Moscow; Moscow; Moscow

References

Supplementary files