1、INTRODUCTION:Kallmann syndrome is an inherited disorder characterized by hypogonadotrophic hypogonadism and anosmia or hyposmia.KS is due to abnormal migration of gonado-tropin-releasing hormone(GnRH)as well as olfactory neurons from olfactory placode to the forebrain and hypothalamus during fetal l
2、ife.Structural olfactory tract abnormalities are well seen on MRIDISCUSSION:Kallmann syndrome is an inherited disorder characterized by hypogonadotrophic hypogonadism and anosmia or hyposmia.The inheritance may be X-linked,Autosomal recessive or Autosomal dominant with variable penetrance.The report
3、ed incidence is 1 in 10,000 men and 1 in 50,000 women.Kallmann syndrome is an anomaly of neuronal migration.Cells that differentiate into Gonadotrophin releasing hormone(GnRH)secreting neurons originate from within embryonic olfactory epithelium and migrate along fascicles of vomeronasal and termina
4、lis nerves into forebrain.This migration of GnRH neurons is arrested in KS resulting in GnRH deficiency followed by different degrees of luteinizing hormone(LH)and follicle stimulating hormone(FSH)deficiencies.Abnormal development of olfactory placode also results in improper development of olfactor
5、y bulbs and sulci.diagnosis of KS in adults is fairly straightforward,depending on the co-existence of anosmia with subnormal levels of gonadal steroids and gonadotrophins.However the diagnosis may be difficult to establish in patients of pre-pubertal age who may require genetic testing and MRI.In s
6、uch patients,MRI enables a presumptive diagnosis of KS to be made by demonstrating characteristic abnormalities in olfactory sulci and tracttory.IMAGINGMorphological abnormalities of olfactory apparatus in KS are best evaluated with MRI.High resolutions coronal fast spin echo T2W images are the pref
7、erred sequences for morphologic evaluation of the olfactory system.Olfactory bulbs are optimally visualized in coronal planes.i t i s e a s i e r t o a p p r e c i a t e anatomical anomalies present in Kallmann syndrome by comparing it to a normal patient.The normal anatomy of the region consists of
8、 the olfactory bulbs located in the olfactory grooves of the anterior cranial fossa.The inferior surface of the frontal lobes usually consists gyrus rectu separated from the medial orbital gyrus(M)by the olfactory sulcus(yellow arrow).oOlfactory bulb:blue arrowsgyrus rectus:Rthe medial orbital gyrus
9、:Molfactory sulcus:yellow arrowMRI FINDINGS:hypoplasia of the olfactory bulbs with olfactory tracts present,aplasia of the olfactory bulbs with olfactory tracts present.aplasia of both olfactory bulbs and olfactory tracts It was also described mild to moderate volume loss in temporal and frontal lobesHypoplasia of anterior pituitary may be secondary to limited stimulation due to absence of hypothalamic GnRH neurons.CONCLUSION:Kallmanns syndrome is a rare genetic disorder.High resolutions coronal fast spin echo T2W is the preferred sequences for morphologic evaluation of the olfactory system.
