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At least 829 records · Page 46Linked to original sources
PubMed2005

Hypopituitarism as a consequence of brain tumours and radiotherapy.

Radiation-induced damage to the hypothalamic-pituitary (h-p) axis is associated with a wide spectrum of subtle and frank abnormalities in anterior pituitary hormones secretion. The frequency, rapidity of onset and the severity of these abnormalities correlate with the total radiation dose delivered to the h-p axis, as well as the fraction size, younger age at irradiation, prior pituitary compromise by tumour and/or surgery and the length of follow up. Whilst, the hypothalamus is the primary site of radiation-induced damage, secondary pituitary atrophy evolves with time due to impaired secretion of hypothalamic trophic factors and/or time-dependent direct radiation-induced damage. Selective radiosensitivity in the neuroendocrine axes with the GH axis being the most vulnerable to radiation damage accounts for the high frequency of GH deficiency, which usually occurs in isolation following irradiation of the h-p axis with doses less than 30 Gy. With higher radiation doses (30-50 Gy), however, the frequency of GH insufficiency substantially increases and can be as high as 50-100%, and TSH and ACTH deficiency start to occur with a long-term cumulative frequency of 3-6%. Abnormalities in gonadotrophin secretion are dose-dependent; precocious puberty can occur after radiation dose less than 30 Gy in girls only, and in both sexes equally with a radiation dose of 30-50 Gy. Gonadotrophin deficiency occurs infrequently and is usually a long-term complication following a minimum radiation dose of 30 Gy. Hyperprolactinemia, due to hypothalamic damage leading to reduced dopamine release, has been described in both sexes and all ages but is mostly seen in young women after intensive irradiation and is usually subclinical. A much higher incidence of gonadotrophin, ACTH and TSH deficiencies (30-60% after 10 years) occur after more intensive irradiation (>70 Gy) used for nasopharyngeal carcinomas and tumours of the skull base and following conventional irradiation (30-50 Gy) for pituitary tumours. Radiation-induced anterior pituitary hormone deficiencies are irreversible and progressive. Regular testing is mandatory to ensure timely diagnosis and early hormone replacement therapy to improve linear growth and prevent short stature in children cured from cancer, and in adults preserve sexual function, prevent ill health and osteoporosis and improve the quality of life.

Brain Neoplasms↗
PubMed1982

Tolerance of the central nervous system to photon irradiation: endocrine complications.

Dose-response isoeffect equations have been determined for hypothalamic pituitary insufficiency following cranial irradiation. Of particular importance is the occurrence of complications at doses substantially less than those commonly used for the treatment of central nervous system tumors. Such complications may be severe and potentially life threatening. These complications occur when a small midline 'target' volume containing the pituitary gland, infundibulum and adjacent inferior hypothalamic structures is irradiated. Direct pituitary irradiation is unlikely to be a factor, at least in some cases. The possible role of incidental hypothalamic irradiation in the control of acromegaly and pituitary dependent Cushing's syndrome is discussed.

Brain↗
PubMed2004

Endocrine consequences of brain irradiation.

Cranial radiation is routinely used to manage pituitary tumours, craniopharyngiomas, primary brain tumours, tumours of the head and neck and, in the past, for the prophylaxis of intracranial disease in patients with acute lymphoblastic leukaemia. If the hypothalamic-pituitary axis falls within the radiation fields, the patient is at risk of developing hypopituitarism. The effect of radiation is determined by the dose and the time that has elapsed since treatment. Classically, growth hormone (GH) is the most sensitive of the anterior pituitary hormones to irradiation, followed by gonadotrophins, adrenocorticotrophic hormone (ACTH) and thyroid-stimulating hormone (TSH). Low-dose irradiation in prepubertal children can initially cause early or precocious puberty and subsequently gonadotrophin deficiency. Higher doses may cause gonadotrophin deficiency and pubertal delay. The ACTH and TSH axes are relatively resistant to the effects of irradiation, but minor abnormalities may occur. Patients who receive cranial irradiation that affects the hypothalamic-pituitary axis remain at risk of developing multiple hormone deficiencies for many years and require long-term follow-up by an endocrinologist.

Adrenocorticotropic Hormone↗
PubMed1978

Treatment of pituitary dependent Cushing's syndrome with closed stereotactic radiosurgery by means of 60Co gamma radiation.

Four patients with pituitary dependent Cushing's syndrome were treated with external irradiation to the pituitary using 60Co gamma irradiation given with a stereotactic technique. The size of the sella turcica was normal or slightly enlarged in all patients. The doses given varied between 7000 and 10 000 rad, and the observation time ranged between 14 and 20 months. Three of the patients showed complete clinical remission and one marked improvement. One patient developed ACTH insufficiency, while none developed insufficient secretion of other pituitary hormones. No complicants of the irradiation were observed.

Adrenocorticotropic Hormone↗
PubMed2003

Sarcomatous change after sellar irradiation in a growth hormone-secreting pituitary adenoma.

BACKGROUND: Although the benefits of radiotherapy for pituitary adenomas are well-documented, post-irradiation sarcomas of the sella are rarely seen, with only 20 cases (mainly of fibrosarcoma) reported in the medical literature. METHOD: We describe a case of post-irradiation sarcoma five years after surgery followed by external-beam irradiation for an extensive and locally invasive growth hormone-secreting tumor. The patient was subsequently given pegvisomant, an antagonist of growth hormone receptor, to control symptoms of growth hormone excess. RESULTS: The patient underwent transsphenoidal resection of the recurrent tumor, followed by adjuvant chemotherapy. This led to significant relief in the patient's symptoms including radiological evidence of tumor shrinkage, but the tumor regrew when, owing to dose-limiting toxicity, chemotherapy was stopped. CONCLUSIONS: Post-irradiation sarcomas of the pituitary are well-recognized but rare. They should be suspected in patients following sellar irradiation who show abrupt onset of new symptoms and appropriate radiological findings, and such tumors may respond to cytotoxic chemotherapy.

Adenoma↗
PubMed1999

Cerebral infarction with ICA occlusion after Gamma Knife radiosurgery for pituitary adenoma: A case report.

Cranial irradiation may lead to accelerated atherosclerotic changes to small or medium sized arteries, but stroke associated with pituitary irradiation is not frequent. A patient treated with Gamma Knife radio-surgery (GKRS) for a pituitary adenoma suffered a cerebral infarction with internal carotid artery occlusion 4 years after radiosurgery. The patient was a 35-year-old male presenting with a visual disturbance. Endocrinological tests were normal. MRI revealed a 4.3 by 4.3 cm diameter invasive macroadenoma of the pituitary, projecting toward the suprasellar region and with cavernous sinus involvement with encasement of both internal carotid arteries (ICAs). GKRS was performed for residual tumor after a transcranial resection. The maximum dose was 40 Gy and the dose to the right carotid artery was below 20 Gy. The delayed hemiparesis was accompanied by a right capsular lacunar infarct shown on MRI. The images also showed a marked reduction in tumor size. Total, right ICA occlusion was confirmed by Doppler ultrasound. The patient had no history or signs of heart disease or metabolic disorder which could predispose to cerebrovascular

Adenoma↗
PubMed1976

Failure of cyprohepatdine to inhibit vasopressin-stimulated cortisol release in a patient with Cushing's disease.

A case of a 21-year-old woman with Cushing's disease due to a pituitary tumor is described. The patient was treated with cyprohepatadine for 4 weeks immediately following pituitary alpha-particle irradiation. A standard vasopressin test to measure ACTH-mediated cortisol release was performed four times: prior to pituitary irradiation, after irradiation, after 4 weeks of cyproheptadine therapy, and off cyproheptadine for 2 weeks. Cyproheptadine failed to modify vasopressin-stimulated cortisol release in the patient described. This study suggests that cyproheptadine, which has previously been shown to decrease ACTH secretion, probably acts principally at the hypothalamic, rather than at the pituitary level.

Adult↗
PubMed1981

Effect of dexamethasone on pituitary-adrenocortical response to acute irradiation stress in rats.

After the irradiation with a lethal dose of 387 mC kg-1 (1500 R) an increase of plasma and adrenal corticosterone concentration was found in male rats (about 250 g body weight) during first 24 h as compared to sham-irradiated animals, the maximum increase being observed at 60 min after irradiation. A second period of corticosterone increase was found at 48 and 72 h. At the same time the adrenal weight increased and severe lesions of gastrointestinal tract were found. In a second experiment dexamethasone (50 mg kg-1) was injected 3 h before irradiation and this prevented the increase of plasma and adrenal corticosterone level at 60 min after irradiation. It was suggested that the degradation of corticosterone might be slowed down during the first period after irradiation, while at the same time the feed-back regulatory mechanism of ACTH release from the pituitary apparently remained intact. The second period of corticosterone increase was apparently due to severe gastrointestinal lesions.

Adrenal Cortex↗