Focal hypoplasia of the olfactory bulb and tract

Axial T2-weighted MRI of a 7-year-old girl with focal hypoplasia of the left olfactory bulb and tract. She also has left optic nerve hypoplasia (not shown). The right olfactory bulb and the optic nerve are of expected size and appearance. She is of normal intelligence and has no neurologic deficits except for decreased visual acuity in the left eye; olfaction is preserved in both nostrils. The pregnancy was uneventful, and the etiology is unknown. The unilateral olfactory bulb hypoplasia was discovered as an unanticipated incidental finding on MRI during the course of investigation of visual impairment in the left eye since birth. (Courtesy of Dr. Xing-Chang Wei, Dept. of Radiology and Imaging, Alberta Children’s Hospital.)