Idiopathic hypogonadotrophic hypogonadism associated with arachnoid cyst of the middle fossa and forebrain anomalies: presentation of an unusual case.

We report a 22-yr-old male patient with hypogonadotrophic hypogonadism (HH) associated with a giant middle fossa arachnoid cyst (AC) diagnosed by magnetic resonance imaging (MRI). He presented with pubertal and growth delay. He also had learning disabilities and anosmia. Laboratory investigation revealed pre-pubertal levels of testosterone and normal results of the combined test of anterior pituitary function, except for in GnRH acute and prolonged test. Cranial MRI showed an AC in left middle fossa with expansion to suprasellar cisterna and several abnormalities like left temporal lobe hypoplasia, left optic tract and bilateral olfactory bulb hypoplasia and left hypothalamic hypoplasia.

Time course of the effects of prenatal gamma irradiation on the dorsal lateral geniculate nucleus of Swiss mice.

A previous study reported that adult mice irradiated at the 16th embryonic day present a severe neuronal number reduction in the dorsal lateral geniculate thalamic nucleus. In the present study, we investigated the time course of the effects of prenatal irradiation on this thalamic nucleus. One day after irradiation, a great number of pyknotic figures were seen mainly in the cerebral proliferative zones. In the geniculate nucleus, only scattered pyknotic figures were identified. On the first week after birth, the geniculate nucleus presented frequent pyknotic figures. From five days after birth onwards, a severe shrinkage of the occipital cortex and a great reduction in the geniculate nucleus neuronal number were found. On the second week after birth this neuronal number reduction reached as high as 75%. At each postnatal analyzed age, severe volumetric geniculate nucleus shrinkage was combined to non-significant neuronal density variations. The presence of few pyknotic figures in the geniculate nucleus one day after irradiation and its delayed neuronal loss indicate an indirect effect of irradiation. We suggest that the effect upon the geniculate nucleus is secondary to the damage of the occipital cortex. A possible interpretation for thalamic neuronal loss is that geniculate neurons fail to establish cortical arbors after major target loss. In this case, the loss of trophic support should also be considered.

Anomalous retinal pathways in the Siamese cat: an inadequate substrate for normal bioncular vision.

All major retinal pathways in the Siamese cat are abnormal, with almost total crossing of the projections to the pretectum and superior colliculus. These projections represent a marked disruption in the customary neural substrate for binocular vision, which implies a consequent impairment in stereoscopic depth perception. Crossed eyes, commonly seen in the Siamese cat, may therefore arise from a neuroanatomical defect in the primary visual pathways.