The Period Prevalence and In-Hospital Mortality of Central Pontine Myelinolysis

Central pontine myelinolysis (CPM) is a dreaded condition that is most likely caused by a rapid rise in the concentration of osmotically active substances and leads to the destruction of the myelin sheaths of pontine neurons. Its most commonly identified cause is rapid correction of the serum sodium concentration in a hyponatremic patient. The broad spectrum of its clinical manifestations includes impaired consciousness and delirium, dysarthria, dysphagia, tetraparesis, and locked-in syndrome, yet some patients are oligo- or asymptomatic. Extrapontine manifestations can arise as well; the totality of clinical features is called osmotic demyelination syndrome (ODS). No effective treatment has been found to date, and thus prevention is key. Current guidelines contain a recommendation for correcting hyponatremia at a rate of 4–8 mmol/L, and never more than 10–12 mmol/L, in the first four hours (1). Multiple studies have shown that rapid serum sodium correction is an important risk factor for CPM (2), yet a meta-analysis of current data nonetheless indicates that mortality is higher after slow correction (4–6 mmol/L/day) than after rapid correction (8–10 mmol/L/day) (3). It is generally accepted that CPM has harmful and potentially fatal consequences, but data on its incidence and outcome are sparse. In this article, we present pertinent data for Germany.

Methods

Data on CPM were obtained from the InEK database of the Institute for the Hospital Reimbursement System in Germany (Institut für das Entgeltsystem im Krankenhaus). The datawere extracted from cases with an ICD-10-GM code of G37.2, indicating a main diagnosis of CPM. Transferred cases were excluded to prevent duplication. The mortality of CPM was determined from deaths during hospitalization. Data from 2019 to 2024 were acquired for this study because they were available in the database.

Demographic stratification was performed with data from the GENESIS database of the Federal Statistical Office, which contains deeply structured official statistics from across Germany. The period prevalence per million person-years was obtained by dividing the number of cases in the defined period by the number of people in the group in question and multiplying by one million. Two-tailed χ²-tests were used for differences between the sexes. Because the study period was short, no time-series analysis was performed.

Results

718 cases of CPM were registered in Germany from 2019 to 2024, corresponding to 1.4 cases per million person-years. CPM was most common in middle age (Table 1). 56 patients (7.8%) died during the study period; mortality was highest in elderly patients. The prevalence of CPM was the same in men and women (375 and 343 cases in the study period, or 1.5 and 1.4 cases per million person-years, respectively; χ² = 2.32, p = 0.13), as was its mortality (29 and 27 cases, or 7.9% and 7.7%, χ² = 0, p = 1). The distribution of cases across Germany is shown in Table 2.

Table 1

The period prevalence and in-hospital mortality of central pontine myelinolysis, stratified by age

Table 2

Period prevalence and in-hospital mortality of central pontine myelinolysis by region (Germany)

Discussion

To our knowledge, this is the largest study of CPM to date. It shows that CPM is a life-threatening condition affecting 1.4 per million persons in Germany each year. It is most common in middle age, but most lethal in old age; thus, there are different risk factors for the development of CPM and for death from CPM. Similar mortality figures were reported in earlier studies. Aegisdottir et al. found an incidence of 0.6 cases per million person-years with a mortality of 7.2% in three months (4). They observed a rising incidence, from 0.3 in 1997–2001 to 0.9 in 2007–2011, and attributed it to improved diagnosis through the increasing use of magnetic resonance imaging (MRI). Our study period was later, and the higher incidence that we found is in line with this secular trend. Fitts et al. reported 16% mortality within 9 months (5). The higher mortality compared to our figure of 7.8% may be explained by the longer follow-up. 7.8% lies in the expected range of mortality after correction of hyponatremia in conformity with the guidelines (3).

Limitations

The reliability of this study depends on the quality of the billing data underlying it. Incorrect coding of CPM may have led to an underestimation of period prevalence and an overestimation of mortality. A precise diagnosis generally requires cranial MRI, but even with this technique, the changes of CPM may only become visible after a delay. The billing data examined in this study exclusively concerned hospitalized patients, so any purely ambulatory cases of CPM were not included. Nor were any data obtained on clinical risk factors, such as the rate of correction of hyponatremia or comorbidities, so no conclusions can be drawn in that connection. The generalizability of the findings beyond Germany is unclear, and the outcomes may have been affected by the COVID-19 pandemic.

Conclusions

CPM is a rare but often fatal condition that requires attention in patients with suggestive clinical manifestations. Other studies have suggested that the rapid correction of hyponatremia is an important risk factor. Prospective, randomized trials are needed to optimize hyponatremia management.

Ludwig Matrisch and Yannick Rau

Conflict of interest statement
The authors state that they have no conflicts of interest.

Manuscript received on 29 September 2025 and accepted after revision on 13 March 2026.

Translated from the original German by Ethan Taub, M.D.

Cite this as:
Matrisch L, Rau Y: The period prevalence and in-hospital mortality of central pontine myelinolysis. Dtsch Arztebl Int 2026; 123: 343–4. DOI: 10.3238/arztebl.m2026.0049

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