NR 38 PITUITARY STALK TRANSECTION SYNDROME ABOUT FIVE

NR 38 PITUITARY STALK TRANSECTION SYNDROME : ABOUT FIVE CASES H. ZAGHOUANI BEN ALAYA, N. MALLAT, Z. ACHOUR, S. MAJDOUB, H. AMARA, D. BAKIR, CH. KRAIEM Imaging department, Farhat Hached Hospital, Sousse, Tunisia

INTRODUCTION : Advances in magnetic resonance imaging (MRI) of the hypothalamic pituitary region may actually explain a number of hormonal disturbances associated with an abnormality of the pituitary stalk The syndrome of interruption of the pituitary stalk (SIPS) is a rare cause of anterior pituitary deficiencies

It is defined by morphological abnormalities revealed by MRI: Interruption or significant thinning of the pituitary stalk a hypoplastic anterior pituitary an ectopic or lacking posterior pituitary The aim of this work is to illustrate the contribution of MRI in this syndrome through five observations.

MATERIAL AND METHODS : Retrospective study of 5 patients Over a period of 5 years from 2006 to 2011 collected from department of medical imaging The age varies from 09 to 23 years : 4 children aged between 09 and 12 years old an adult of 23 years Sex : 3 males and 2 females

The reason for consultation and exploration : Short stature with anterior pituitary deficit (n=5) Primary amenorrhea (n=1) Diabetes insipidus (n=1) A pituitary MRI was performed in all patients : MRI 1. 5 Tesla GE Thin Sagittal and coronal (3 mm) Fast spin echo T 2 and T 1 before and after gadolinium injection

RESULTATS : MRI showed an abnormality of the pituitary stalk in all cases : Interruption of the pituitary stalk : complete transection (n=4) and incomplete with a filiform pituitary stalk (n=1) Ectopic posterior pituitary gland appeared as an area of high signal intensity in the midline at the median eminence (n=4) Hypoplasia of the anterior pituitary (n=5) Absence of the posterior pituitary gland associated with Arnold Chiari I malformation (n=1)

(a) Case 1 : 9 year old child, panhypopituitarism Fig. 1 (a, b) : coronal unenhanced T 1 -weighted MR imaging : ectopic posterior pituitary gland ( ) seen as an area of high signal intensity in the midline at the median eminence (a). the pituitary stalk is not visible ( ) (b) Fig. 1 (c, d) : Gadoliniumenhanced coronal and midsagittal T 1 -weighted MR imaging : The pituitary stalk is not visible (b). The ectopic posterior pituitary gland is visible (a, b) (c) (d)

(a) Case 2 : 10 year old child, short stature with diabetes insipidus (b) Fig. 2 (a, b) : midsagittal unenhanced and contrast material– enhanced T 1 -weighted MR imaging : small anterior pituitary gland( ), absence of the habitual pituitary posterior lobe hyperintense signal within the sella turcica cavity and also within the median eminence (a). the pituitary stalk is also not visible even after administration of Gadolinium ( ) (b). (c) Fig. 2 (c) : midsagittal T 2 T 1 -weighted MR imaging : ectopia of cerebellar tonsils ( ) with V 4 in place : Arnold Chiari I malformation

Case 3 : 12 year old child, short stature with Growth Hormone deficiency (a) (b) (c) Fig. 3 (a, b, c) : sagittal and coronal unenhanced T 1 -weighted MR imaging : small anterior pituitary gland( ) (a), presence of the ectopic posterior pituitary ("bright spot“) at the median eminence level ( ) (b, c). the pituitary stalk is not visible ( ) (b).

Case 4 : 23 year old patient, primary amenorrhea with gonadotropin deficiency Fig. 4 : midsagittal unenhanced T 1 -weighted MR imaging : ectopic posterior pituitary in hypersignal ( ), small anterior pituitary gland, pituitary stalk interruption in its incomplete form (thin pituitary stalk) ( ).

DISCUSSION : � � � Definition : The SITP was first Fujisawa et al described in 1987 by It is a syndrome defined by morphological abnormalities revealed by MRI: a thin or interrupted pituitary stalk � a hypoplastic anterior pituitary � an ectopic or absent posterior pituitary �

� Physiopathology : The etiology of pituitary stalk interruption is not completely understood. Two theories have been proposed : § § Traumatic theory: facing a high proportion of history of fetal distress, breech presentation and of head trauma in patients with a SIPS Malformative theory: The SITP is frequently associated with abnormalities of the midline Facial dysmorphism may be associated There is as familial forms The genetic theory remains the most creditable versus the traumatic theory

� Clinical : SIPS is often revealed in the neonatal period and childhood. His revelation in adults is exceptional This syndrome is clinically discussed in presence of hypopituitarism: Isolated most often a Growth hormone deficiency Multiple with a normal posterior pituitary function Classically, there is an isolated GH deficiency if the pituitary stalk is thin and a panhypopituitarism if the pituitary stalk interruption is complete Isolated GH deficiency can progress to panhypopituitarism and requires biological monitoring for life

• Imaging : The diagnostic strategy of growth retardation currently leaves an important place to imaging and particularly to cerebral MRI thanks to: its high contrast resolution its character multiplanar the absence of bone artifacts of the base (limit of CT) MRI offers a morphological study of the hypothalamic-pituitary region and search for associated brain abnormalities of the midline

The browsing protocol: Sagittal and coronal thin (2 -3 mm) Centered on the hypothalamic-pituitary FSE T 1 -weighted sequence FSE T 2 -weighted sequence Injection of contrast material paramagnetic The whole brain must be explored to eliminate the associated malformations

1. Anomaly of the posterior pituitary: It appears in spontaneous hypersignal on T 1 -weighted and enhances after gadolinium injection It is ectopic and it is localized whether at the infundibulum (50%) or at the pituitary stalk or sometimes even in the hypothalamus This ectopic hyperintensity can be located anywhere along the pituitary stalk

2. Anomaly of the pituitary stalk: Complete form: not visualized pituitary stalk whatever the sequence Incomplete form: with a filiform pituitary stalk or visible only after gadolinium injection This classification has a prognostic value, since in the complete forms the hormonal deficiency is most often multiple

3. Anomaly of the anterior pituitary: The anterior lobe is often hypoplastic (height less than -2 SD compared to normal values according to age) But even when it is of normal size, the dynamic sequence may reveal, among patients with GH deficiency, delayed contrast enhancement of the anterior pituitary

4. Malformations of the midline: Arnold Chiari malformation type I Basipharyngial Canal Total or partial agenesis of the corpus callosum Agenesis or hypoplasia of the septum and the optic chiasma (septo-optic dysplasia) Dandy-Walker malformation

If MRI is normal in the context of growth hormone deficiency : It has a prognostic impact because the deficit is often incomplete or even transitional Some studies have shown the higher frequency of genetic abnormalities in the group of patients with GH deficiency and normal MRI, which allows to select patients for genetic studies

CONCLUSION : The SIPS is a rare congenital malformation, responsible for most cases of growth hormone isolated deficiency but also for multiple anterior pituitary deficits. MRI is currently the most performed imaging means for the diagnosis of this malformation and the prognostic approach : Morphological study of the hypothalamic-pituitary Establish clinical and radiological correlations Detect associated brain malformations.

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