Clinical features, ARIX and PHOX2B nucleotide changes in three families with congenital superior oblique muscle palsy.

We analyzed nucleotide changes in 3 genes, ARIX, PHOX2B, and KIF21A, in 6 patients of 3 families with congenital superior oblique muscle palsy. Three exons of ARIX, 3 exons of PHOX2B, and exons 8, 20, and 21 of KIF21A were amplified by polymerase chain reaction from genomic DNA isolated from the peripheral blood. The DNA fragments were directly sequenced in both directions. In 2 different families, a heterozygous nucleotide change, ARIX 153G>A, in the 5'.-untranslated region was found in common between a father and daughter with muscle palsy and between a mother and daughter with muscle palsy (Family No. 1 and No. 3). In the other family (Family No. 2), a heterozygous 15-nucleotide deletion, PHOX2B 1124del15, resulting in loss of 5 alanine residues in the alanine repeat of the protein, was found in the daughter with muscle palsy and her father with normal traits, but was not found in the mother with muscle palsy. No KIF21A nucleotide change was found in any patients. The ARIX 153G>A polymorphism might be a genetic risk factor for the development of congenital superior oblique muscle palsy.

Paretic side/normal side ratios of cross-sectional areas of the superior oblique muscle vary largely in idiopathic superior oblique palsy.

PURPOSE: To search for a new definition of muscle hypoplasia in congenital or idiopathic superior oblique muscle palsy. DESIGN: Retrospective case-control study. METHODS: Cross-sectional areas of the superior oblique and 4 rectus muscles near the eye globe-optic nerve junction were measured by an image analysis software on magnetic resonance images of 50 patients with congenital or idiopathic superior oblique muscle palsy and 45 patients with other disease conditions serving as a control. The paretic side/contralateral normal side ratios of the cross-sectional areas and the left side/right side ratios were calculated for the superior oblique muscle palsy patients and the control patients, respectively. RESULTS: The 95% confidence intervals in paretic side/contralateral side ratios of cross-sectional areas of the superior oblique muscle were 0.55 to 0.80 in the right-side superior oblique muscle palsy, and 0.48 to 0.75 in the left-side palsy, while the 95% confidence interval in the left side/right side ratios was 0.99 to 1.00 in the control. The 95% confidence intervals in the left side/right side ratios of the 4 rectus muscles were 1.00, both in the superior oblique muscle palsy and in the control. CONCLUSIONS: The muscle hypoplasia could be defined as such when the paretic side/contralateral side ratios of cross-sectional areas of the superior oblique muscle on magnetic resonance images fell outside the 95% confidence interval of the ratios in normal controls.

Postural stability changes during the prism adaptation test in patients with intermittent and constant exotropia.

PURPOSE: Computerized static stabilometry is a clinical test in neurologic and muscular diseases to assess postural stability or body sway in a quantitative manner. The purpose of this study was to examine whether postural stability would change in the process of the prism adaptation test in patients with intermittent and constant exotropia. METHODS: Postural stability was measured before the prism adaptation test and immediately, 15 minutes, and 60 minutes after the prism adaptation test by computerized static stabilometry in 17 consecutive adult patients with exotropia, including 10 patients with intermittent exotropia and seven with constant exotropia. Stabilometric parameters were compared between patients with intermittent and those with constant exotropia for 60 minutes by repeated-measures analysis of variance as statistical analysis. RESULTS: The Romberg quotients for the root mean square areas of the sway path (cm(2)), the area in the condition of the patients' eyes open, divided by that in the condition of the patients' eyes closed, increased significantly in the time course of the prism adaptation test and returned to the pretest level in patients with intermittent exotropia and in patients with constant exotropia (P = 0.0173). No significant difference in the Romberg quotients was noted between the patients with intermittent exotropia and those with constant exotropia. CONCLUSIONS: Postural instability became more pronounced by the prism adaptation test in the patients with exotropia. Binocular visual and motor perceptional changes induced by the prism adaptation test could lead to postural instability, with adaptation taking place 60 minutes after the start of the test.