Abstract 93: Clinical and radiological discordance in pituitary stalk interruption syndrome in patients with short stature due to growth hormone deficiency

Introduction: Pituitary stalk interruption syndrome (PSIS) is a rare congenital disorder with an estimated incidence rate of 5/1,000,000 births. Pituitary stalk interruption syndrome (PSIS) is characterized by a triad of a thin or interrupted pituitary stalk, aplasia or hypoplasia of the anterior pituitary, and absent or ectopic posterior pituitary (EPP) seen on magnetic resonance imaging (MRI). It can present either at birth or later in life. PSIS is very heterogeneous with respect to its hormonal, clinical, and radiological manifestations. In this study, we analyze the clinical, biochemical, and radiological characteristics of PSIS, in patients with growth hormone deficiency (GHD) cohort. Materials and Methods: The study was conducted in 3000 bedded multi-specialtytertiary care centerin South Tamil Nadu between the year 2020 and 2022, after IEC approval. 75 short stature patients with GHDwere included in this study. Among them, 14 patients were diagnosed with PSIS. Their clinical, biochemical, and radiological characteristics and response to GH therapy were analyzed. Results: 14 (18.6%) patients were diagnosed with PSIS. The mean age at diagnosis was 11.8 ± 2.6 years (Range 2.3-18 years). The male to female ratio was 2.5:1. The mean birth weight was 2.9 ± 0.4 kg. 21.4% of patients had a breech presentation. 4 (28.57%) patients had birth asphyxia, and one (7.14%) had micropenis and bilateral cryptorchidism at birth. Only one (7%) patient had midline clinical manifestations like cleft lip and cleft palate. In addition, two (14%) had bilateral squint with nystagmus. 8 (57.15%) patients had combined pituitary hormone deficiency (CPHD),5 (35.71%) had isolated growth hormone deficiency (IGHD) and only one (7.14%) had central diabetes insipidus. EPP was seen near median eminence in 6 (42.85%) patients, elsewhere (along the stalk, near the floor of the third ventricle, near the hypothalamus) in 4 (28.57%) patients, and absent in 4 (28.57%) patients. 2 (14.28%) patients had extra pituitary malformations (EPM) in MRI. PSIS cohorts who were receiving GH therapy had better growth response on an average of 10 cm per year when compared to other etiologies during the first 3 years of treatment. Conclusion: Male gender, sporadic onset, breech presentation, and the presence of extra pituitary clinical manifestations like midline defects, and nystagmus are more common in patients with PSIS. Severe GHD as well as multiple pituitary hormone deficiency were more common but posterior pituitary involvement is very rare despite classical MRI findings. Clinical suspicion of these features in all short stature may lead to early diagnosis and prompt initiation of GH treatment. Hence individual hormonal sufficiency or deficiency should be established in all PSIS and based on MRIhormonal therapy should not be initiated.