Osmotic demyelination syndrome (ODS), also known as central pontine myelinolysis, is a demyelinating condition that affects the pons region of the brain stem. It occurs when hyponatremia (low sodium levels) are corrected too rapidly, such as when sodium levels increase more than 12 mmol/L in a 24 hour period. Symptoms include paralysis, dysarthria, and dysphagia. Risk factors include chronic alcoholism and hyponatremia. While prognosis was once poor, improved imaging techniques now allow for earlier diagnosis and treatment with rehabilitation. Prevention through controlled correction of hyponatremia is key to avoiding ODS.

1. Osmotic demyelination
syndrome
A demyelinating syndrome also called central pontine myelinosis

2. • A demyelinating disease is any disease of the nervous system in which
the myelin sheath of neurons is damaged (Wikepedia, 2014).
www.nature.com

3. Osmotic Demyelination Syndrome
• “central pontine myelinolysis”
• Demyelinating lesion in the brain that occurs with overly rapid
correction of hyponatremia
• Characterized by acute paralysis, dysphagia, and dysarthria
• Most common in those with chronic hyponatremia (usually caused by
alcoholism)

4. Case
• 68 y/o male admitted to hospital 1 days ago with electrolyte
disturbances, dehydration, seizures and chronic alcohol abuse.
• Day 1 of admission level of consciousness decreased to GSC 7 but
improved to 14/15. Only to deteriorate again 4 days later to 3/15
• Transferred to the critical care unit for airway management and
neurological review. CT scan of brain to be completed on transfer was
normal.
• Admission sodium level 108mmol/dl on day one increased to
128mmol/dl. Now 142mmol/Dl
• Presumed pontine demyelinating syndrome

5. Pathophysiology
• initially encephalopathic or presenting with seizures from
hyponatraemia, then recovering rapidly as normonatraemia is
restored.
• Patient deteriorate several days later. The initial signs of the Osmotic
demyelination syndrome, which reflect this second phase,
• include dysarthria and dysphagia (secondary to corticobulbar fibre
involvement),
• a flaccidquadriparesis (from corticospinal tract involvement) which later
becomes spastic.
• This originates from involvement of the basis pontis, The basilar part
of pons is the anterior portion of the pons (Martin R. J. 2004)

6. • if the lesion extends into the tegmentum of the pons:
• pupillary, oculomotor abnormalities may occur.
• There may be an apparent change in conscious level reflecting the ‘‘locked-in
syndrome’’ that a large lesion in this site is likely to produce (Martin 2004).

7. • This may give a similar presentation as discussed in this course as
related to Bobbi brain stem stroke.
• The question is would this patient recover

8. Prognosis
• Once considered bleak for most syndromes were diagnosed post
mortem
• The improvement in CT and MRI techniques now allows diagnosis
early
• Neither clinical features nor extent of radiological change are
predictive. The outcome may be death, disability, or recovery to
virtually normal level of function.
• However there is a 25% of patients from most studies who survive
with significant neurological deficits from paralysis to severe
Ataxia.(King 2010)

9. treatments
• The management of patients with CPM and ODS is prolonged
neurorehabilitation.
• In addition to the:
• generally applied therapeutic measures, there are four additional treatment
modalities. These are
• administration of TRH, plasmapheresis, corticosteroids alone or in combination with
plasmapheresis,
• intravenous immunoglobulin
• No specific choice
• Prevention is the best treatment

10. Osmotic Demyelination Syndrome
Prevention
• Controlled correction of severe hyponatremia
• Correction rate=0.5-1.0meq/L/hr, with not more than 12meq/l
correction in 24 hrs; should receive no more than 8-10mmol of
sodium per day
• Management: Supportive
• Prognosis is poor

11. References
• Bhattacharya, A. K., Bera, A B. and Roy, S. (2007) A Case Study Osmotic
Demyelination Syndrome. Journal of Indian Academy of Clinical Medicine 8 (2).
• King, Mitchel and Rosner (2010) Osmotic Demyelination syndrome. American
Journal of Medical Science, 339(6).
• Martin R. J. (2004) Central Pontine and Extra Pontine myelinosis: The Osmotic
Demylenation Syndrome. Journal Neurol Neurosurgical Psychiatry, 75
(Supplement ii).
• Nature.com (2014) available at: http://www.nature.com/scitable/content/the-
fate-of-demyelinated-axons-14463695 Accessed July 18th.
• Wikepedia, (2014) available at:
http://en.wikipedia.org/wiki/Demyelinating_disease accessed June 7th 2014.