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.