Diagnosis is based on the appearance of demyelinating brain lesions on CT or MRI. MRI is more sensitive than CT; however, even an MRI scan can appear normal for as long as 4 weeks after symptoms appear.7 Therefore, an initial negative radiologic study in a high-risk patient who develops neurologic symptoms does not exclude ODS. Earlier detection is possible with diffusion-weighted MRI, which is most sensitive and can detect lesions within 24 hours of developing symptoms.11 The severity of the lesion does not correlate with severity of symptoms.
Studies reveal a considerable range in prognosis of patients with clinically symptomatic ODS. A study of 44 patients with central pontine myelinolysis, of which 42 had chronic alcoholism, reported that 34% had no significant functional deficits at follow-up, 34% had minor neurologic deficits, and 31% became dependent on personal help. Outcome did not depend on the extent or severity of neurologic symptoms or the severity of concomitant systemic complications.12
Because of its poor prognosis, prevention of ODS is important. Because ODS commonly is caused by overly rapid correction of hyponatremia, it is necessary to adhere to guidelines for treating chronic hyponatremia (Table 2). If overcorrection occurs, therapeutic re-lowering of serum sodium can be considered, but has not been validated in controlled trials. Based mainly on case reports that suggest benefit from early re-lowering serum sodium in patients with ODS symptoms, experts recommend the following:
• administer desmopressin, 2 to 4 μg, every 8 hours parenterally
• replace water orally or as 5% dextrose in water intravenously (3 mL/kg/hr)
• check serum sodium hourly until serum is reduced to goal.6
Bottom Line
Hyponatremia is the most common electrolyte disorder encountered in practice. Osmotic demyelination syndrome often is preventable, with considerable morbidity and mortality. Psychiatrists should be aware of this condition because it could be an adverse effect of many psychiatric medications and there are some psychiatric illnesses in which hyponatremia is a potential risk. In hyponatremic patients with persistent nonspecific neurologic or neuropsychiatric symptoms and negative CT imaging, additional imaging, such as MRI, is warranted.
Related Resources
- Braun MM, Barstow CH, Pyzocha NJ. Diagnosis and management of sodium disorders: hyponatremia and hypernatremia. Am Fam Physician. 2015;91(5):299-307.
- Vaidya C, Ho W, Freda BJ. Management of hyponatremia: providing treatment and avoiding harm. Cleve Clin J Med. 2010;77(10):715-726.
Drug Brand Names
Carbamazepine • Tegretol
Oxcarbazepine • Trileptal
Desmopressin • Stimate, DDAVP
Lithium • Eskalith, Lithobid
Pentoxifylline • Trental, Pentoxil
Methylprednisolone • Medrol
Quetiapine • Seroquel
Disclosure
The authors report no financial relationships with any company whose products are mentioned in this article or with manufacturers of competing products.