PURPOSE: @entity1645 ( @entity1645 ) is characterized by deformed hindbrain. This study aimed to quantitatively evaluate the alterations in position of hindbrain after @entity6804 ( @entity6804 ), and to identify the factors associated with syrinx resolution in pediatric @entity1 with @entity1645 . METHODS: Eighty-seven @entity1 , aged from 5 to 18  years, who underwent @entity6804 for @entity1645 between September 2006 and September 2012 were retrospectively reviewed. On mid-sagittal MR images, the position of medulla oblongata and cerebellum was quantitatively evaluated preoperatively and at follow-up. The maximal syrinx/cord (S/C) ratio and syrinx length were also measured. Significant improvement of syrinx was defined as a more than 20  % decrease in maximal S/C ratio or length on follow-up MRI. RESULTS: @entity51 were found in 51 of the 87 @entity1 preoperatively and 37 (72.4  %) of them obtained improvement of their symptoms at the last visit. Overall, upward shifting of the tip of cerebellar tonsil was observed in 66 (75.9  %) @entity1 at the last follow-up. Moreover, the mean longitudinal distance of the tip of cerebella tonsil changed from 16.47      5.00 to 13.89      4.38  mm (P  <  0.001) at final follow-up. Significant syrinx resolution was noticed in 79 (90.8  %) cases. @entity76 were found in 85  (97.7  %) of our @entity1 preoperatively and 78 (91.8  %) of them acquired @entity76 after @entity6804 . The improvement of maximal S/C ratio was significantly correlated with upward shifting of the tip of cerebellar tonsil (P  =  0.023). CONCLUSIONS: Following @entity6804 for @entity1645 , position and morphology of the cerebellar tonsil could revert to normal in most of the pediatric @entity1 , and the upward shifting of the tip of cerebellar tonsil is significantly correlated with syrinx improvement. From this study, @entity6804 without shunting may be effective for syrinx secondary to @entity1645 in pediatric population.

Syrinx resolution is correlated with the upward shifting of cerebellar tonsil following posterior fossa decompression in pediatric XXXX with @entity1645 .

@entity6804 :: ('MESH:D015192', 'Disease') :: ['PFD', 'Posterior fossa decompression'] @entity1 :: ('9606', 'Species') :: ['patients'] @entity1645 :: ('MESH:D001139', 'Disease') :: ['CMI', 'Chiari malformation type I'] @entity51 :: ('MESH:D009461', 'Disease') :: ['Neurological deficits'] @entity76 :: ('MESH:D002526', 'Disease') :: ['Pointed cerebellar tonsils', 'round cerebellar tonsils']
@entity1 :: (9606,Species) :: ['patients']
