Growth hormone deficiency in children: role of magnetic resonance imaging in assessing aetiopathogenesis and prognosis in idiopathic hypopituitarism

Relevance of Pituitary Gland Magnetic Resonance Imaging Results with Clinical and Laboratory Findings in Growth Hormone Deficiency

BACKGROUND The present study investigated the relationship between detection of organic pathologies with magnetic resonance imaging of the pituitary gland, clinical and laboratory findings, and treatment response. MATERIAL AND METHODS The study included a total of 183 patients who had isolated growth hormone deficiency, received at least 1 year of treatment, returned regularly for follow-ups, and whose pituitary magnetic resonance images were available. The patients were divided into 2 groups: those with and without pathological evidence with magnetic resonance imaging. Clinical and laboratory features and treatment responses were compared between patients with and without pathological evidence with magnetic resonance imaging. RESULTS Of the 183 patients, 105 were females and 78 were males, and 114 patients (62.2%) were prepubertal and 69 patients (37.8%) were pubertal. Their mean age was 10.01±3.25 years (1-17.6 years). Pituitary images of 153 (83.6%) patients were normal. Of the patients with detected pathologies (16.4%), 19 (10,4%) had pituitary hypoplasia, 5 (2.7%) had partial empty sella, 3 (1.7%) had ectopic neurohypophysis and 3 (1.7%) had empty sella, pineal, and arachnoid cyst. A statistically significant increase was observed in the height increase rate after treatment compared to before treatment in both groups (p<0.001). However, the group with pathology had a statistically significant (p=0. 007) post-treatment increase height rate. Although in the group with pathology there was a lower L-DOPA and clonidine peak GH response, there was not any statistically significant difference between the 2 groups (p=0.051, p=0.113). Pituitary gland length was also shorter in the group with pathology compared to the group without pathology (P<0.001). CONCLUSIONS Magnetic resonance imaging is a useful tool in assessing GH deficiency pathogenesis and in predicting treatment response.

Congenital hypopituitarism: clinical, molecular and neuroradiological correlates

OBJECTIVE

Recent studies have suggested that mutations in genes encoding several hypothalamo-pituitary (H-P) transcription factors result in hypopituitarism [isolated GH deficiency (IGHD) and combined pituitary hormone deficiency (CPHD)], which may in turn be related to the neuroanatomy revealed by magnetic resonance (MR) imaging. Although studies have focused on patients with either optic nerve hypoplasia (ONH) or isolated hypopituitarism with normal optic nerves, few studies have compared the two groups. We aimed to relate the clinical phenotype of a large cohort (n = 170) of children with congenital hypopituitarism including septo-optic dysplasia (SOD) attending a single centre to the neuroradiological and genetic findings.

DESIGN

Clinical, biochemical, MR imaging and molecular data were analysed retrospectively in 170 patients with or 'at-risk' (with ONH) of hypopituitarism to determine predictors of hypopituitarism.

RESULTS

The presence of ONH was significantly associated with an absent septum pellucidum [odds ratio (OR) 31.5, 95% confidence intervals (CI) 7.3-136.6, P < 0.001], an abnormal corpus callosum (OR 10.5, 95% CI 3.8-28.6, P < 0.001) and stalk abnormalities (OR 2.3, 95% CI 1.2-4.2, P = 0.009). The risk of hypopituitarism was 27.2 times greater in patients with an undescended posterior pituitary (95% CI 3.6-205.1, P < 0.001). Anterior pituitary hypoplasia (OR 3.1, 95% CI 1.3-7.0, P = 0.006) and an absent pituitary stalk (P < 0.001) were also significantly associated with hypopituitarism. With respect to the type or severity of hypopituitarism, CPHD was more often associated with an abnormal corpus callosum (OR 6.1, 95% CI 1.4-27.4, P = 0.008) and stalk abnormalities (OR 2.8, 95% CI 1.3-6.1, P = 0.006). Male to female ratio was significantly greater in patients with normal optic nerves (3.3:1) as compared with those with ONH (1.2:1). The prevalence of diabetes insipidus, thyrotrophin and ACTH deficiencies was significantly greater in patients with ONH as compared with 'idiopathic' hypopituitarism. Mutations in pituitary transcription factors and genes regulating GH secretion were rare (5/170) in this cohort of patients with sporadic hypopituitarism.

CONCLUSION

Our data suggest that individuals presenting with ONH are at high risk for neuroradiologic and endocrine abnormalities. The neuroradiologic features are predictive not only of the presence, but also of the type, of hypopituitarism. The association of midline abnormalities with hypopituitarism in this cohort suggests a common developmental origin for these features, the aetiology of which remains unidentified in the majority of cases.

Isolated growth hormone deficiency

Isolated growth hormone deficiency (IGHD) represents conditions of GH deficiency that are not necessarily associated with other pituitary hormone deficiencies or with an organic lesion. Three sub-categories of IGHD have been clinically identified (IGHD types 1-3), and IGHD type 1 has been further separated into IGHD types 1a and b. However, this clinical sub-categorization of IGHD may need reconsideration due to the recent identification of molecular heterogeneity within each sub-type of IGHD. In a small number of children with IGHD, defects in the GH, GH-releasing hormone receptor (GHRH-R), and GH1 genes have been identified. In most cases, no cause for IGHD can be identified; however, the proportion of idiopathic IGHD cases may be decreasing due to identification of causative factors. The phenotype of IGHD is variable depending in part on the underlying genetic disorders in the affected individuals. Several studies have focused on the usefulness of MRI findings in patients with GHD but anatomic abnormalities of the pituitary gland are variable. We review current studies and the clinical, biochemical, and molecular features described for different groups of affected individuals with IGHD.

Panhypopituitarism: genetic versus acquired etiological factors

OBJECTIVE

Mutations in the genes encoding pituitary transcription factors (mainly PROP1, POUF1 and HESX1) are responsible for familial combined pituitary hormone deficiency (CPHD) and septo-optic dysplasia (SOD) while only a low percentage of mutations are the cause of sporadic forms. Indeed, it has been suggested that environmental rather than genetic factors could be important in the pathogenesis of CPHD.

PATIENTS AND METHODS

Thirty-six sporadic patients diagnosed with CPHD or SOD were included in the study. All coding exons and intron-exon boundary regions of PROP1, POUF1 and HESX1 were amplified by PCR and subsequently sequenced.

RESULTS

Two novel missense mutations in the HESX1 gene (Q117P, K176T) were identified in two patients. Polymorphisms in PIT1 and PROP1 were also detected. A higher percentage of breech delivery in male patients with CPHD versus females was observed.

CONCLUSIONS

The low percentage of mutations found in the most common transcription factors involved in CPHD show that a better characterization of hormonal and morphological phenotypes is necessary for patients with CPHD included in genetic studies, and other genetic or non-genetic factors have to be taken into account.

Pituitary stalk compression by the dorsum sellae: possible cause for late childhood onset growth disorders

PURPOSE

The purpose of this study was to evaluate the relationship between pituitary stalk compression by the dorsum sellae and clinical or laboratory findings in short stature children.

MATERIALS AND METHODS

We retrospectively reviewed magnetic resonance images of the pituitary gland and pituitary stalk for 34 short stature children with growth hormone (GH) deficiency and 24 age-matched control cases. We evaluated the degree of pituitary stalk compression caused by the dorsum sellae. Body height, GH level, pituitary height and onset age of the short stature were statistically compared between cases of pituitary stalk compression with associated stalk deformity and cases without compression.

RESULTS

Compression of the pituitary stalk with associated stalk deformity was seen in nine cases within the short stature group. There were no cases observed in the control group. There were no significant differences found for body height, GH level and pituitary height between the cases of pituitary stalk compression with associated stalk deformity and cases without compression. However, a significant difference was seen in the onset age between cases with and without stalk compression.

CONCLUSION

Pituitary stalk compression with stalk deformity caused by the dorsum sellae was significantly correlated with late childhood onset of short stature.

MRI findings of the pituitary gland in short children born small for gestational age (SGA) in comparison with growth hormone-deficient (GHD) children and children with normal stature

BACKGROUND

Disturbances in the GH/IGF-I axis are reported in 25-60% of short children born small for gestational age (SGA). We hypothesized that these abnormalities might be related to abnormalities in the pituitary region. Therefore, the results of magnetic resonance imaging (MRI) of short SGA children were compared to MRI results of other groups of short children and to normal controls.

PATIENTS AND METHODS

MRI was performed in four groups of short children: SGA children without GH deficiency (SGA group; n = 17), SGA children with isolated GH deficiency (SGA + IGHD group; n = 10), non-SGA children with isolated GH deficiency (IGHD group; n = 24) and non-SGA children with multiple pituitary hormone deficiencies (MPHD group; n = 15). MRI was also performed in children with normal stature (control group; n = 13). Pituitary height (PH) and thickness of the pituitary stalk (PS) were measured and their relationship with the maximum GH peak during a GH stimulation test, serum IGF-I and IGFBP-3 levels was evaluated.

RESULTS

Short SGA children either with or without IGHD did not show major anatomical abnormalities in the hypothalamic-pituitary region in contrast to 58% of the non-SGA IGHD children and 87% of the MPHD children who had anatomical abnormalities. PH in SGA children without GHD was normal whereas it was significantly lower in SGA children with IGHD. The lowest PHs were measured in non-SGA children with MPHD. A moderate decrease in PH was associated with significantly lower maximum serum GH peaks and lower serum IGF-I and IGFBP-3 levels.

CONCLUSION

Measuring PHs in children with less severe GHD, who underwent MRI as part of the diagnostic process, might support the diagnosis of GHD even in the absence of anatomical abnormalities. Our study demonstrates that there is no indication to perform MRI of the pituitary region in short children born SGA without GHD.

Use of magnetic resonance imaging in short stature: data from National Cooperative Growth Study (NCGS) Substudy 8

The primary use of magnetic resonance imaging (MRI) in the evaluation of children with short stature (SS) is to discover lesions in the central nervous system (CNS), particularly tumors that may require intervention. MRI has a secondary role in identifying structural abnormalities responsible for growth hormone deficiency (GHD). We examined data from the National Cooperative Growth Study (NCGS) Substudy 8 to determine how American physicians are using MRI in evaluating children with SS. Of the 21,738 short children enrolled in NCGS, 5% underwent MRI during their follow-up. Children who had GH stimulation testing were more likely to have had an MRI than those in whom no GH stimulation test was performed (19% vs 2%, p <0.0001). Moreover, children diagnosed with severe GHD (maximum GH <5 ng/ml) were more likely to have an abnormal finding on MRI. Of these patients, 27% demonstrated an abnormality as compared to 12% and 12.5% in patients with partial GHD and normal GH stimulation test results (>10 ng/ml), respectively. Abnormalities unrelated to the hypothalamus or pituitary represented 30% of these findings, while disorders in pituitary anatomy, including pituitary hypoplasia, pituitary stalk interruption, and ectopic posterior pituitary, represented an additional 30% of abnormal MRI examinations. CNS tumors comprised 23% of abnormal findings in these patients. We conclude that MRI provides significant value in the evaluation of children with SS, by identifying CNS tumors associated with growth failure as well as anatomical abnormalities of the pituitary. These findings are useful in confirming the diagnosis of GHD in children and identifying potential candidates for continued GH replacement in adulthood.

Late onset of adrenocortical failure in GH deficiency with invisible pituitary stalk: a case report of a 48-year-old Japanese man and review of the literature

ACTH deficiency gradually develops in patients with growth hormone deficiency (GHD) who have abnormalities of the pituitary stalk on magnetic resonance imaging (MRI) following perinatal complications. We report here a rare case of GHD manifesting ACTH deficiency in middle age. A 48-year-old male patient was admitted to our hospital due to fever and hyponatremia. He was diagnosed as GHD and hypothyroidism at the age of 9, and had received lysine treatment until age 20, which was then replaced by thyroid hormone. He was not mentally retarded, but was the shortest in his class throughout his schooldays, reaching a final height of 148 cm. Hormonal examination revealed the presence of hypoadrenalism as indicated by poor responses of plasma cortisol to intravenous administration of corticotropin-releasing hormone (CRH) and insulin-induced hypoglycemia. Plasma ACTH responded well to CRH, but not to insulin-induced hypoglycemia, indicating that his hypoadrenalism was of hypothalamic origin. MRI showed an invisible pituitary stalk and relatively small pituitary gland. Since he had a perinatal abnormality, the damage around the pituitary and GHD could have originated from birth. In the literature, around 60% of GHD patients with pituitary stalk abnormalities develop hypoadrenalism due to ACTH deficiency, and more than 90% of such cases are diagnosed by age 30. We suggest that the appearance of hypoadrenalism should be carefully monitored in GHD patients with pituitary stalk abnormalities even after they reach middle age.

Posterior pituitary ectopy in children with idiopathic growth hormone deficiency

AIMS

To evaluate the underlying pathogenesis in children with pituitary hormone deficiency by means of high resolution MRI of the brain.

PATIENTS/METHODS

Thirty-seven children with short stature and isolated GH deficiency (IGHD, n = 17) or multiple pituitary hormone deficiency (MPHD, n = 20) were subjected to an MRI of the brain at the age of 1.0-17.3 years. The anatomic condition of the hypothalamo-pituitary area was analyzed and the height of the pituitary gland was measured and compared to the data of age-matched healthy subjects.

RESULTS

Seventy percent of the patients had a characteristic anomaly: the adenohypophysis was hypoplastic, the infundibulum was absent and the posterior pituitary lobe was ectopic at the bottom of the median eminence. The height of the anterior pituitary was significantly reduced in these patients (1.9 +/- 0.1 mm; mean +/- SD) when compared to age-matched healthy controls (4.1 +/- 0.8 mm, p<0.001) or hypopituitary patients with a normal MRI (4.3 +/- 0.8 mm). MPHD was found in 62% of patients with the pituitary anomaly whereas only 27% of children with a normal MRI had MPHD (p<0.05).

CONCLUSIONS

The pathogenesis of the pituitary anomaly is unknown; a disorder during embryonal development or perinatal events have been discussed as causal factors. MRI should have a prominent position in the work-up of hypopituitary children. When an anatomical malformation is visualized by MRI, the diagnostic terminology should be adapted accordingly.

Magnetic resonance imaging in growth hormone deficiency: relationship between endocrine function and morphological findings

Magnetic resonance imaging (MRI) using gadopentetate dimeglumine (Gd-DTPA) improves the delineation of hypothalamic-pituitary structures and facilitates the detection of anatomical abnormalities which are indicators of permanent growth hormone deficiency (GHD). The aim of this study was to determine the frequency of neuroradiological abnormalities in 85 (52 M, 33 F) patients with hereditary or idiopathic forms of isolated GHD (IGHD) or multiple pituitary hormone deficiency (MPHD) and also to investigate the relationship between anatomical findings and hormonal status. Pituitary hypoplasia with absent or thin infundibulum and ectopic posterior pituitary (EPP) were the most frequent findings in 39 patients with MPHD, whereas in 46 patients with IGHD the most frequent finding was pituitary hypoplasia without neuroradiological abnormalities. All patients whose infundibulum was not visualized after Gd-DTPA injection belonged to the MPHD group; therefore, absence of pituitary stalk can be a good indicator of the severity of hormonal deficiencies. Pituitary hypoplasia was found in all patients with familial IGHD. Among patients with abnormalities of the hypothalamic pituitary area on MRI, normal or breech delivery frequency distributed equally. Therefore it seems that mechanical or hypoxic prenatal events cannot be the primary etiological factor in all patients with neuroradiological abnormalities since half of these patients had normal delivery and birth history. The localization of the bright spot of the posterior pituitary at the level of the median eminence, midstalk position or at the end of the infundibulum may suggest a neuronal migration defect which may occur during early embryogenesis. In conclusion, in children with GHD a careful examination of the hypothalamic pituitary area by MRI after enhancement helps to establish the diagnosis and predicts the prognosis.

Sequential contrast-enhanced magnetic resonance imaging in the diagnosis of growth hormone deficiencies

The purpose of the present study was to assess the presence and the time-course of contrast-enhancement in the pituitary gland and pituitary stalk of 24 patients with isolated growth hormone (GH) deficiency and multiple pituitary hormone deficiency. The patients were evaluated clinically (auxological measurements), endocrinologically (spontaneous GH secretion and GH stimulation tests) and with conventional MRI scans. In addition, fast-framing dynamic magnetic resonance imaging (MRI) with Gd-DTPA enhancement was used to quantitate the time course of contrast enhancement within the neurohypophysis, pituitary stalk, postero-superior adenohypophysis and antero-inferior adenohypophysis. In 3 patients without evidence of abnormalities at normal conventional MRI scans (normal anterior lobe and pituitary stalk, normal posterior lobe) and a high response to the GRF provocation test, sequential time-resolved Gd-enhanced MRI demonstrates reduced contrast enhancement in the pituitary stalk. These findings are consistent with impairment in stalk vasculature, presumably located at the level of the portal venous system, and could play a role in the pathogenesis of pituitary hormonal deficiency.

Is the persistence of isolated GH deficiency in adulthood predicted by anatomical hypothalamic-pituitary alterations?

The aim of this study was to verify the persistence in adulthood of GH deficiency diagnosed in childhood and treated with hGH in childhood and to study whether anatomical hypothalamic-pituitary alterations evaluated by magnetic resonance (MR) imaging could predict it. To this goal, in six GHD adults (3 males and 3 females aged 17.2-24.5 yr, BMI 21.8 +/- 1.3), we studied anterior pituitary hormone response to GHRH (1 microgram/kg iv)+pyridostigmine (120 mg po)+ GnRH (100 micrograms iv) +TRH (400 micrograms iv)+hCRH (100 micrograms iv) as well as brain MR imaging. In childhood, the diagnosis of severe isolated GHD had been done based on auxological findings as well as on GH response < 7 micrograms/L after two classical provocative stimuli. In the present study, hormonal responses showed the persistence of severe isolated GHD in 4 out of 6 patients (peak, mean +/- SEM: 3.8 +/- 0.6, range 2.6-4.8 micrograms/L). In these patients, IGF-I levels were found low or low-normal. In other 2 patients, a clear GH response to stimulation (peak: 51.3 and 43.0 micrograms/L, respectively) together with normal IGF-I levels were found. No other anterior pituitary hormone deficiency was present in all subjects. MR imaging showed pituitary hypoplasia in all patients with persistent GHD; in 2 out of them, pituitary stalk interruption and ectopic neurohypophysis was also present. On the other hand, MR imaging showed normal hypothalamo-pituitary morphology in the 2 subjects with normal somatotrope response. In conclusion, our present data indicate that testing with a potent stimulus such as GHRH+pyridostigmine is a reliable method to assess the persistence of GH deficiency which associates with anatomical hypothalamic-pituitary alterations at the MR imaging. Patients with transient GH deficiency in childhood and normal pituitary GH reserve in adulthood have normal hypothalamic-pituitary MR imaging.

Effective Use of Magnetic Resonance Imaging in the Assessment of Children with Possible Growth Hormone Deficiency

OBJECTIVE

To present our experience with diagnosis of growth hormone (GH) deficiency in children and to determine which patients are most likely to benefit from magnetic resonance imaging (MRI).

METHODS

We retrospectively reviewed medical records of pediatric patients who underwent assessment for possible GH deficiency during a 6-year period and correlated clinical variables, stimulated GH responses, and MRI findings.

RESULTS

Of 100 children who failed outpatient GH screening tests, 14 were classified as at risk for hypothalamic pituitary defects, and 86 were considered not at risk, having short stature only. Patients were further stratified by age, sex, growth variables, maximal GH response to provocative testing, and MRI findings. A significant relationship existed between the presence of risk factors, maximal GH of <5 mg/L, and sellar defects. With no risk factors, MRI scans showed normal findings in 15 of 17 patients with maximal GH of <5 mg/L, in 33 of 34 patients with GH between 5 and 10 mg/L, and in all 35 patients with GH of >10 mg/L. Abnormal MRI findings included posterior pituitary ectopy, decreased pituitary size, absent midline central nervous system structures, enlarged infundibulum, and hamartoma. In one child with a 4-year history of growth failure and a maximal GH of 3.5 mg/L, craniopharyngioma was diagnosed.

CONCLUSION

MRI scans should be obtained in any child with multiple pituitary hormone deficiencies, hypoglycemia, ophthalmologic anomalies, low-stimulated GH, or acquired growth failure. Otherwise asymptomatic children with growth delay and maximal GH of >10 mg/L do not need routine MRI screening. Such a strategy could result in substantial cost savings.

Primary empty sella: differences and similarities between children and adults

To identify possible differences between empty sella in children and adults we studied 43 subjects (age 13.6 +/- 5.4 years, range 4.1-27 years) with hypothalamic-pituitary disorders and empty sella at magnetic resonance imaging. Pituitary function, presence of non-endocrine symptoms, perinatal history, sellar volume, pituitary height, midline or intrasellar anatomical abnormalities were evaluated. Twenty subjects had isolated growth hormone deficiency, 17 multiple pituitary hormone deficiency and 6 puberty disorders (3 precocious puberty, 2 idiopathic delayed puberty, 1 Kallmann syndrome). The group with multiple pituitary hormone deficiency had a higher percentage of subjects with complete empty sella, i.e. pituitary height < 2 mm (p = 0.016), or intrasellar anatomical abnormalities (p = 0.0002) than the other groups. The subjects with puberty disorders had a mean sellar volume higher than the other groups (p < 0.05). Apart from pituitary dysfunction, symptoms of the empty sella syndrome were infrequent (9.3% of cases) in our subjects. The age of our subjects, the frequent association between empty sella and pituitary dwarfism and the non-enlarged sellae suggest a different aetiology, perhaps congenital, for empty sella in our subjects. As in adults, empty sella may be associated with both pituitary hypo- and hyperfunction.

Abnormal development of the sella turcica and lack of pituitary visualization in a patient with partial hypopituitarism

We report the case of a 17-year-old girl presenting short stature (height 149 cm, below the 3rd percentile), obesity (weight 83.5 kg, body mass index 37 kg/m2) and secondary amenorrhea, in whom endocrinological evaluation disclosed an absolute lack of GH responsiveness to both suprapituitary challenges and repetitive growth hormone releasing hormone administration together with failure of plasma gonadotropins and PRL, low under basal conditions, to rise in response to GnRH and insulin-hypoglycemia, respectively. In contrast, basal and stimulated TSH and ACTH secretions were normal. Radiological examination of the skull revealed virtual absence of the pituitary fossa due to the lack of sellar cavum and dorsum, while magnetic resonance was unable to detect any pituitary tissue. A mucosal cleft of the nasopharynx, compatible with a pharyngeal hypophysis, was disclosed at endoscopy. This is an unusual case of developmental abnormality including lack of formation of the sella turcica and incomplete caudal migration of the embryonal anterior pituitary, resulting in ectopically located--likely pharyngeal--pituitary tissue. In view of the occurrence of spontaneous menarche and of a growth impairment less severe than one would expect considering the degree of GH deficiency, it is conceivable that the ectopic pituitary tissue has lost, in time, some of its secretory ability.

Dystopic neurohypophysis

A dystopic neurohypophysis was noted incidentally at autopsy in a 51 -year-old man with no endocrine abnormality. The dystopic gland was situated in the upper region of the tuber cinereum and macroscopically simulated a neoplasm. The pituitary fossa contained only anterior hypophyseal elements. Review of the literature disclosed 19 such cases discovered at autopsy; 11 occurred in normal individuals with no endocrine abnormality. Radiological study revealed 145 additional cases. Except for the 6 occurrences described in normal individuals, the rest occurred in patients with anterior pituitary dysfunction. No instance of isolated diabetes insipidus has been reported due to dystopia of the neurohypophysis. Dystopia of the neurohypophysis in normal individuals should be distinguished from those occurring in patients with anterior pituitary abnormalities. The former represent a true dystopia and are not associated with perinatal injury, in contrast to the latter, which are acquired dystopias secondary to regeneration of the neurohypophysis and are associated with perinatal injury. Although anterior and posterior pituitary glands are formed by appositional growth, their development and functional status are entirely independent. Finally, the most significant clinical feature of dystopic neurohypophysis is the absence of any related symptoms and this condition should always be considered in the clinical differential diagnosis of hypothalamic lesions. In such patients, a surgical procedure may be avoided because other hypothalamic lesions, such as hamartomas and astrocytomas, are more frequently symptomatic.

Modern imaging techniques in GH secretory disorders

Magnetic resonance images of the pituitary-hypothalamic area in patients with GH secretory disorders, divided into two groups (hypersecretory and hyposecretory), were studied. In the first group there were 42 patients with pituitary adenoma; size, signal characteristics, direction of growth, and type of enhancement were analyzed and compared with similar studies in 40 age and sex matched control patients with non-GH secreting pituitary adenomas. No significant differences were found except for a higher frequency of chiasm involvement and a more pronounced contrast enhancement in the control group. The hyposecretory group was composed of 101 patients with congenital idiopathic growth hormone deficiency (CIGHD). MR revealed morphological abnormalities consisting of hypoplastic anterior pituitary and ectopic posterior pituitary (PPE) in 59 patients, without evidence of a complete pituitary stalk; in 42 patients the posterior pituitary was in normal position and the pituitary stalk visible. The group with PPE showed a greater frequency of multiple pituitary hormone deficiency (51% vs 12%), breech delivery (30% vs 7%) and associated congenital brain anomalies (12% vs 7%). These data suggest that CIGHD could be the result of a congenital midline brain anomaly in a significant proportion of patients.

Magnetic resonance and the diagnosis of short stature of hypothalamic-hypophyseal origin

Magnetic resonance imaging was performed in 23 patients with short stature (7 had multiple pituitary hormone defect, 11 had isolated growth hormone deficiency and 5 had normal variant short stature) to investigate if there is a relation between magnetic resonance findings and results of endocrine tests. Magnetic resonance imaging of patients with multiple pituitary hormone deficiency or with serious isolated growth hormone deficiency (growth hormone < 3 micrograms/l) revealed an interrupted pituitary stalk and ectopic neurohypophysis or a mass. In patients with less serious isolated growth hormone deficiency (growth hormone > 3 micrograms/l) or with normal variant short stature, the technique revealed a normal or hypoplastic hypophysis. Magnetic resonance appears to be a useful second-level diagnostic tool in defining the type of alteration in growth defects of endocrine origin.

Magnetic resonance imaging in patients with hypopituitarism

In patients with hypopituitarism, magnetic resonance (MR) imaging of the hypothalamus and pituitary has disclosed a high incidence of hypoplasia of the anterior pituitary lobe, attenuation or transection of the pituitary stalk, and formation of an "ectopic" posterior pituitary lobe at the base of the hypothalamus. These anatomic abnormalities may be associated with other congenital malformations of the central nervous system, or may be due to an in utero toxic or infectious insult, perinatal trauma, neonatal asphyxia and hypoxia, head injury, or hemorrhage into a pituitary adenoma. The progressive development of defects in pituitary hormone secretion in such patients is probably due to continued atrophy of an anterior pituitary remnant with a limited vascular supply unstimulated by hypothalamic neuropeptides. By contrast, in patients with isolated hypogonadotropic hypogonadism, hypothalamic pituitary anatomy is normal, although abnormalities of the olfactory sulcus are present in patients with anosmia and hypogonadotropism (Kallmann syndrome). In most patients with central diabetes insipidus, the neurohypophysis is absent on MR scan.

Magnetic resonance imaging in the diagnosis of growth hormone deficiency

Forty-six patients with idiopathic growth hormone deficiency were examined by magnetic resonance imaging at a mean (+/- SEM) age of 9 +/- 1 years (range 15 days to 20 years). They were classified into two groups according to MRI images: group 1 (n = 29) had pituitary stalk interruption syndrome and group 2 (n = 17) had normal pituitary anatomy. All patients with pituitary stalk interruption had a pituitary height at less than -2 SD for age; three had no visible anterior pituitary lobe. By contrast, the pituitary height was less than normal in only 10 patients (60%) with normal pituitary anatomy. Growth hormone deficiency was transient in one of the seven patients with normal pituitary anatomy and height. The group with pituitary stalk interruption had the first symptom of growth hormone deficiency at an earlier age (2.8 +/- 0.6 vs 5.5 +/- 1.2 years; p less than 0.001), were of smaller stature (-4 +/- 0.2 vs -3 +/- 0.2 SD; p less than 0.01) and had lower GH peak response to provocative testing (3 +/- 0.4 vs 5 +/- 0.5 ng/ml; p less than 0.001) than did the group with normal pituitary anatomy. Their pituitary gland was also shorter (2.5 +/- 0.2 vs 3.5 +/- 0.2 mm; p less than 0.01). All the patients with multiple pituitary deficiencies except one (n = 19) belonged to this group. One girl with pituitary stalk interruption and deficiencies in growth hormone and thyroid-stimulating hormone had advanced central precocious puberty. We conclude that the evaluation of the shape and height of the pituitary gland by MRI is an additional tool for the diagnosis of growth hormone deficiency. The presence of pituitary stalk interruption confirms this diagnosis and is predictive of multiple anterior pituitary deficiencies. The lack of a significant increase in perinatal abnormalities in this group and the association of pituitary stalk interruption with microphallus and with facial or sella abnormalities suggest that this appearance may have an early antenatal origin. The finding of a familial case of pituitary stalk interruption suggests a genetic origin.