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Nasser H. Kashou, Arif O. Mohsin, Mark A. Smith, Lawrence E. Leguire, IV; Tractography of Infantile Nystagmus Syndrome. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4688.
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White matter structure in the pons and in the cerebellum was investigated between INS patients and normal age-matched controls utilizing fMRI-DTI techniques. The working hypothesis is that there are structural white matter differences (e.g., number of fiber track projections) between INS and normal subjects.
DTI scans were acquired from a total of 7 subjects. INS subjects (N= 4) included three family members, a mother and her two daughters, with autosomal dominant INS. We used age and gender matched normal controls (N=3). The Magnetic Resonance (MR) scanning was performed on a 3.0 Tesla imager at Nationwide Children’s Hospital. DTI acquisition parameters were: TE=76 ms; TR=10 s; flip angle = 90o single-shot; full k-space; 128x128 acquisition matrix interpolated to 256x256 with a field of view (FOV) = 30 cm, generating an in-plane resolution of 1.72 mm2 with full head coverage. Slice thickness = 5 mm; slice gap = 1.5 mm. Diffusion MR images were obtained from 25 directions with a b-value of 1000 s/mm2 along with a b = 0 image with no diffusion gradients. Trackvis and Diffusion toolkit were used for the tractography and the two regions of interest (ROI) for quantifying and comparing the number of tracks were used, the pons and the cerebellum.
Consistent with the working hypothesis, white fiber tracks in the Pons and in the Cerebellum were reduced in INS subjects compared to normal subjects by 15.5% and 7.9%, respectively.
In the current study, we utilized diffusion tensor imaging (DTI) to compare number of white matter tracks for INS patients and controls. Based on our review of the literature, we are the first to use these imaging techniques to assess the white matter tracks of patients with nystagmus. A loss of fibers at the level of the Pons and Cerebellum could contribute to the involuntary ocular-motor dysfunction characterized by INS. Further investigation of the cerebellum-brainstem-cerebrum connections using DTI will be crucial in identifying trouble regions in these pathways.
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