1. Abstract No: 1439

2. D Shaw 1, T Ahmed 2, M Islam 2, G Ishak 1 1 Seattle Children's Hospital, University of Washington; Seattle, WA 2 Dhaka Hospital of ICDDR,B; Dhaka, Bangladesh

3. Purpose 3- 5% of infants hospitalized in Dhaka with diarrhea and dehydration present with hypernatremia (serum sodium > 150). Clinical concern had been raised as to neurocognitive impairment in a subset of infants surviving dehydration treated with oral rehydration who presented with hypernatremia. This observation prompted a pilot study including MR imaging in this subset of infants treated with this oral rehydration protocol.

4. Materials and Methods 1.5T MRI was performed immediately post hospital discharge following oral rehydration for an episode of diarrheal induced dehydration associated with hypernatremia at the primary pediatric hospital in Dhaka, Bagladesh. Clinic data was collected and scans (T1, T2, DWI and GE) retrospectively reviewed by two pediatric neuroradiologists. The study was approved by the local IRB.

5. Results 4 children studied (ages 6-14 months) Admitted with serum sodium between 165 and 208 meq/l; All treated with oral rehydration (ORS) over 46-70 hours (no IV fluids); (see following clinical data table). All were reported clinically normal at discharge. Brain MR were abnormal in 3 of 4 children; mostly symmetric extrapontine foci of diffusion restriction were seen in central gray and internal capsule. In one infant, additional patchy areas of diffusion restriction were seen in the central white matter. No evidence of venous thrombosis or hemorrhage was detected.

6. W/A=weight for age (minus score indicates under-nutrition), W/L=weight for length (minus score indicates wasting); GORS=glucose based ORS Patient Clinical Data : Patient G4 P-0537617 G3 P-0540842 G1 P0541887 G2 P-0543952 Age6 months8 months3 months 27 days1 yr 2 months Nutrition statusNo OedemaNon pitting oedemaNo oedema Initial Na(meq/l)208.2189.7183.01164.88 Correction with GORS 1320ml over 70 hours 1008ml over 46 hours 888ml over 48 hours 1247ml over 48 hours Final Na(meq/l)145.8143.4142.18145.1 OutcomeDischarge: full recovery Final Na(meq/l)145.8143.4142.18145.1 Outcome Discharged with full recovery EEG findings Focal slowing restricted to left posterior temporal and occipital region Normal Ac excess of slow waves noted over the right posterior temporal and right occipital regions Normal

7. Case 4: 6 month old. DWI trace: bilateral diffusion restriction in thalami, internal capsules and hippocampi

8. Case 3: 8 month old: DWI trace: symmetric diffusion restriction in anterior limbs of internal capsule, medial putamen, asymmetric patchy restriction in cerebral white matter.

9. Case 2; 14 months old: DWI trace: mild symmetric diffusion restriction in Globus pallidus and medial putamen.

10. Discussion Diffusion restriction seen in 3 of 4 cases. Largely symmetric involvement. Central gray and white matter tracts, internal capsule. Only 4 cases, but the most extensive findings were seen in the case with the highest sodium level.

11. Discussion Considering the clinical setting, osmotic myelinolysis was thought the likely etiology Whether secondary to or preceding electrolytic correction is unresolved (imaging was done outside the treating institution and only available after discharge). No evidence of venous thrombosis or hemorrhage was seen.

12. Osmotic demyelination syndrome: (ODS) Overly rapid correction hypo, and hypernatremia. Other electrolytic derangements and clinical scenarios have also been implicated (hypophosphatemia and hypokalemia; acute hepatitis; renal failure; hemodialysis; emesis gravidarum; anorexia nervosa; diabetes mellitus; Wilson disease; leukemia; lymphoma; AIDS; various autoimmune diseases)

13. Osmotic demyelination syndrome Malnutrition has been a potential factor since the original reports in alcoholic liver disease/anorexia being present apparently in some cases without rapid correction. Initial cases of Central Pontine Myelinolysis (CPM) with overly aggressive/rapid correction of hyponatremia in alcoholic liver disease were fatal, diagnosed at autopsy; with modern imaging there has been increasingly recognized to be a broader phenotype, non-fatal CPM and extrapontine myelinolysis.

14. Prior Literature in Pediatrics: Ranger et al 2012: Central Pontine and Extrapontine Myelinolysis in Children: A Review of 76 Patients Ranger A M et al. J Child Neurol 2012;27:1027-1037 76 pediatric cases from 5 decades Osmotic demyelination syndrome attributed to either very high or very low serum sodium. Vast majority (62 of 65, 95%) of patients presented with at least moderate neurologic deficit ranging from ataxia, altered gait, dysarthria to generalized seizures, quadraplegia, coma, locked-in syndrome. Increasing number of reported cases, decrease mortality: 94% of cases prior to 1990; 7% of cases after 1989

15. Discussion Brain cells adjust to changes in extra cellular osmolarity by changing levels of osmolytes: inositol, betaine, glutamine. Rapid changes in Na + can exceed the ability for cells to adjust intra cellular osmolytes; seen usually with IV hydration. Malnutrition may compromise the cellular response to changes in osmolarity.

16. Summary MRI of infants treated with oral rehydration for dehydration presenting with hypernatremia revealed patterns of diffusion restriction suggesting osmotic demyelination, without perceived overly rapid correction or use of IV fluids. Osmotic demyelination syndrome has been usually associated with rapid correction of severe osmolyte derangement.

17. Conclusion Though the originally reports of ODS cases involved the pons and were uniformly fatal, modern imaging has recognized less severe injuries and extrapontine myelinolysis. The present cases may have been complicated by malnutrition resulting in abnormalities in metabolism or protein osmolytes. Recognition of this injury should prompt evaluation of rehydration strategies in infants presenting with dehydration and hypernatremia in this population potentially complicated with compromised nutrition.