Inter- and Intra-Hemispheric Fibers of Olfactory and Motor Areas inKallmann Syndrome with Defective Corpus Callosum

Kallmann syndrome (KS) is a form of hypogonadotropic hypogonadism with variable disturbances of olfaction, with some patients having complete anosmia. In this study, we report observations of cerebral white matter connectivity in a rare patient diagnosed with KS associated with a defective corpus callosum (DCC) (KS-DCC) using non-invasive tractography-based diffusion tensor imaging (DTI). In the partial CC, two genua remnants were observed. The KS-DCC patient had a normal life without cognitive impairment and had a normal intelligence quotient, manifesting only the two common symptoms hypogonadotropic hypogonadism and anosmia. Mirror movements were not observed. Compared with normal, DTI tractography of the olfactory related area in the KS-DCC patient revealed fewer inter-hemispheric fibers between right and left olfactory areas (including olfactory tubercle and anterior commissure). Overall, the KSDCC patient had higher numbers of intra-hemispheric fibers bilaterally and fewer inter-hemispheric connecting fibers. The higher numbers of intra-hemispheric fibers connected the right thalamus and right supplementary motor area (SMA) and the left thalamus and left SMA. The fewest number of fibers observed in the KS-DCC patient were those connecting right and left SMA. The Probst bundle together with increased intra-hemispheric fibers may indicate plastic rewiring of corpus callosum connections.