Clinical, radiographic, and electrophysiologic findings in patients with achiasma or hypochiasma

摘要

Objective: To report the clinical, electrophysiologic, and radiographic analysis of four patients presenting with nystagmus and diagnosed with achiasma or hypochiasma and summarize all 11 patients reported with this syndrome. Methods: Each patient underwent complete ophthalmologic examination, fundus photography, ocular motor recordings (OMR), visual evoked potentials (VEP), visual field testing (VFT), and magnetic resonance imaging (MRI) of the optic pathways. Results: Reduced vision, strabismus, optic nerve dysplasia, congenital nystagmus (CN), and see-saw nystagmus were present in all patients. One of these four patients had congenital hydrocephalus and three of the four patients had amblyopia. Monocular VFT was full in the older patients tested. OMR showed dysconjugate vertical, multiplanar ocular oscillations with CN slow phases, well-developed foveation periods, and occasional spontaneous uniocular saccades. VEPs showed crossed asymmetry and increased latency consistent with uncrossed optic pathways and optic nerve dysplasia. Specific MRI studies showed no chiasm in three patients and a hypoplastic chiasm in one. Conclusions: These patients further elucidate the spectrum of human achiasma/hypochiasma. Careful intraocular and ocular motor evaluation found optic nerve anomalies and see-saw nystagmus in all patients. Patients with congenital optic nerve hypoplasia/dysplasia with or without other midline neurologic defects should be carefully evaluated for the clinical presence of see-saw nystagmus (SSN). The occurrence of the conditions CN, SSN, and optic nerve anomaly strongly suggests achiasma/hypochiasma. Electrophysiologic and radiographic evaluations should be considered in these patients.