Aims To assess the functional and clinical outcome in a sizeable cohort of patients with osmotic demyelination syndrome (ODS) and to characterise the factors which could predict the final outcome.

Methods Twenty five consecutive patients with ODS formed the study cohort. The diagnosis of ODS was based on clinical features with corroborating imaging findings. Two functional scales—Functional Independent Measure (FIM) and Disability Rating Scale (DRS)—were applied to assess the functional status at the time of admission, discharge and last follow-up. Patients who became independent for activities of daily living (ADL) at last follow-up were classified as favourable outcome, and those who died or became dependent for ADL were classified as a poor outcome group respectively. The Fisher exact test and Mann–Whitney U test were used to assess categorical and continuous variables respectively.

Results The mean age at diagnosis was 53±14 years. Five (20%) had central pontine myelinolysis, seven (28%) had extrapontine myelinolysis, and 13 (52%) had both. Hyponatraemia and hypokalaemia were noted in 20 (80%) and 10 (40%) patients respectively. Six (24%) received intravenous methylprednisolone. Eleven (46%) had a favourable outcome at a mean follow-up of 2.2±2.5 years. Hyponatraemia ≤115 mEq (p=0.04), associated hypokalaemia (p=0.04) and low Glasgow Coma Scale (GCS) (p=0.008) at presentation were predictive of poor outcome. The mean FIM score at admission (p=0.05) and at discharge (p=0.01), and mean DRS at admission (p=0.05) were predictive of poor outcome.

Conclusions Higher GCS scores, better scores in functional scales in hospital, less severe hyponatraemia and absence of superadded hypokalaemia predicted favourable outcome.