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At least 469 records · Page 26Linked to original sources
PubMed1991

Effect of cranial irradiation on hypothalamus-pituitary function: follow-up study one year after radiotherapy.

Hypothalamic pituitary functions were studied in 24 patients before, 6 months after and 1 year after cranial irradiation with or without radiosensitizing chemotherapy for nasopharyngeal carcinoma (NPC). The estimated average total dose was 5,000 cGy to the hypothalamus and pituitary gland. The radiosensitizing chemotherapy used was endoxan, 4,900 +/- 873 mg (mean +/- SD) and/or methotrexate, 113 +/- 30 mg. All patients had normal pituitary function before radiotherapy. There was a progressive increase in baseline serum thyrotropin (TSH) after radiotherapy. The basal serum follicle stimulating hormone (FSH) was significantly increased 6 months after radiotherapy and remained so at 1 year after radiotherapy. The TSH response to thyrotropin-releasing hormone (TRH) also progressively increased after radiotherapy, suggesting primary hypothyroidism due to neck irradiation. The peak serum TSH response to TRH became delayed after radiotherapy, suggesting a defect in TRH release. In male patients who did not receive chemotherapy, the LH response to luteinizing hormone-releasing hormone (LHRH) decreased after radiotherapy. After an initial rise in the FSH response to LHRH 6 months after radiotherapy, there was a reduction in the FSH response at 1 year. This suggests a defect in LHRH pulsatile release. However, in male patients who received radiosensitizing chemotherapy, both the FSH and LH responses to LHRH had declined at 1 year after radiotherapy, as compared with their responses at 6 months. However, these were still higher than those obtained before radiotherapy. This suggests further GnRH neuron damage, which was previously masked by chemotherapy-induced primary hypogonadism. The adrenocorticotropic hormone (ACTH) response to ovine corticotropin-releasing hormone (CRH) had not changed further at 1 year after radiotherapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Long-term results of stereotactic radiosurgery to the pituitary gland in Cushing's disease.

Gamma radiation from 60Co delivered with stereotactic technique was given to the pituitary gland in 35 patients, aged 18-65 years, with Cushing's disease. The doses were 70-100 Gy in each single irradiation. The size of the sella turcica was normal in the majority of the patients. The observation time was 3-9 years in 29 patients. Out of them, 14 (48%) obtained clinical remission and normal urinary cortisol after one irradiation. Eight achieved remission after two to four irradiations. In total, 22 out of 29 patients (76%) obtained remission. In 12 of them remission was obtained in 1 year and in another 10 within 3 years. No recurrences were observed. Improvement was seen in 2 patients after one and three irradiations. Bilateral adrenalectomy was performed in 5 patients owing to unsatisfactory effect of irradiation. Pituitary insufficiency with gonadotropin, thyrotropin or corticotropin failure was demonstrated in 12 of 22 patients in remission. This occurred 4 months to 7 years after the first irradiation. Another 6 patients were followed less than 3 years after the first irradiation. Two obtained remission after the first treatment, whereas the other 4 improved. Stereotactic pituitary irradiation is suggested as a non-invasive therapeutic alternative in Cushing's disease for example in patients with considerable surgical risk or as a supplement to pituitary microsurgery.

Adolescent↗
PubMed1990

[Magnetic resonance imaging of the pituitary gland and the sella turcica region. Normal and pathological aspect].

MRI may be presently considered as the optimal imaging technique for the study of the sellar and parasellar region. Excellent anatomic and multiplanar approach, absence of irradiation, spontaneous visualization of vascular elements, absence of artefacts characterize MRI. The normal aspect of the sellar region is first described on both spin-echo, T1 and T2 weighted images. MRI appearance of micro and macroadenomas is described. The use of paramagnetic contrast agents (Gadolinium DTPA or DOTA) is widely accepted as a useful complementary diagnostic tool. Moreover the most commonly encountered lesions of the sellar region are reviewed and their behaviour on MRI discussed. Although MRI is an outstanding imaging technique, particularly useful for the study of the sellar region it must be stressed that MRI lacks of specificity. As a consequence, it is of utmost importance to compare MRI with clinical and biological examinations in order to reach a confident final diagnosis.

Adenoma↗
PubMed2000

Acute and long-term complications of therapeutic radiation for skull base tumors.

Acute toxicity from radiation of skull base tumors typically resolves spontaneously within days to weeks after completion of therapy. Long-term complications have a latency of months to years after radiation and are usually irreversible. The need to keep the probability of chronic toxicity at an acceptable level has determined the upper limits of radiation doses for the treatment of tumors. The threat of chronic toxicity thus affects the ability to control skull base tumors with radiation. Use of conformal radiation techniques with image guidance, allowing minimization of normal tissue volume receiving significant radiation doses and close regulation of doses to specific structures, provides a low probability of long-term complications. Such conformal techniques may result in improved tumor control by allowing delivery of higher radiation doses to the tumor while maintaining an acceptable level of risk for chronic toxicity. Symptoms resulting from chronic radiation toxicity are indistinguishable from those due to tumor progression. In most cases in which radiation is used to treat tumors throughout the body, symptoms developing months after radiation are secondary to tumor recurrence and not due to toxicity from radiation. Notable exceptions are pituitary hormonal dysfunction after radiation for pituitary adenoma and cranial neuropathy after radiosurgery for vestibular schwannoma. With the recent evolution in radiosurgery techniques involving MR imaging guidance, decreased single doses in SRS, and fractionation of radiation dose in SRT, the probabilities of vestibular schwannoma progression and cranial nerve toxicity are approximately equal. Even in the case of visual field deficit after radiation therapy for a pituitary macroadenoma (for which the probability of tumor mass progression is only 5%-10%), the cause of the deficit is more likely to be progressive tumor than radiation-induced neuropathy. Consequently, diagnosis of a late-term radiation complication must be made only after verifying that the tumor has not progressed.

Brain↗
PubMed2001

Does the lead apron and collar always reduce radiation dose?

The possibility that personal lead shielding devices can increase absorption of radiation has not been entertained. The purpose of the present investigation specifically was to determine whether pituitary dose might be increased when a leaded apron and thyroid collar are used. Thermoluminescent dosimeters (TLDs) were used to measure absorbed dose. They were calibrated at the kVp used in the clinical situation and a calibration curve relating light output to dose was generated. Lithium fluoride TLD discs were placed in the pituitary gland region of a Rando-Alderson female human phantom. The equivalent of 100 transpharyngeal exposures were delivered. The resultant light output from recovered dosimeters was converted to a uGy value using the calibration curve. The experiment was repeated using a 0.25 mm lead equivalent collar and apron fitted to the phantom in the customary manner. The entire process was repeated in order to have 30 dosimeters for the unshielded and 30 dosimeters for the shielded conditions. A further 30 dosimeters were sham irradiated and served as controls. A statistical comparison between unshielded and shielded conditions was performed. When the leaded apron and thyroid collar were used the absorbed dose to the pituitary gland was increased significantly (P < 0.05). Following this a second group, using a different dosimetry system and a male phantom repeated the experiment. In both cases, the shielded phantom received significantly higher dose to the pituitary region than the unshielded.

Absorption↗
PubMed1999

[Disorders of endocrine function after brain tumor therapy in childhood].

BACKGROUND: Advances in the therapy of malignant brain tumors in children have led to a significant improvement in survival rates over the last few decades. As a result, the recognition and treatment of late effects have become more important. In addition to secondary tumors and deficiencies in cognitive and intellectual skills, the resulting endocrine disturbances play an important role. METHOD: Own data and literature review. RESULTS: Deviations from the normal growth hormone secretion are usually recognized first and are most common, and have already been observed after conventional whole brain irradiation with 18 Gy. With some delay, other hypothalamo-pituitary deficiencies may occur, including panhypopituitarism. Puberty may come too early or too late or may not appear at all. Girls in particular, frequently experience an early and rapid pubertal development after brain tumor therapy, which may lead to further reduction in height due to an accelerated bone maturation. Functional disturbances of the thyroid and adrenal glands due to hypothalamic or pituitary deficiency are less common, and usually seen only after a radiation dose of over 40 Gy. CONCLUSION: Survivors of childhood brain tumors must be considered as long-term survivors, in whom the first therapy-induced long-term side effects appear almost immediately after the end of therapy. Maximum quality of life for the individual patient can only be achieved by long-term care and close cooperation of specialists in the different medical disciplines involved.

Brain↗
PubMed1983

Pituitary-adrenal axis activity in rats after whole-body irradiation. Comparison with plasma cortisol evolution in four cases of human protracted whole-body irradiation.

Plasma ACTH and adrenal and plasma corticosterone levels were studied in rats during 30 days after LD50 irradiation. Plasma cortisol levels were studied in man after protracted whole-body irradiation. In both cases, a period of great instability of adrenal function was associated with bad clinical conditions. Then, a period of adrenal dysfunctioning, reversible with time, occurred in rats and in one patient.

Adrenal Glands↗
PubMed2006

Endocrine intervention during irradiation does not prevent damage to the thyroid gland.

Radiation to the head-neck region may damage the thyroid gland, leading to hypothyroidism or thyroid carcinoma. Outcomes of radiation protection by lowering plasma thyroid-stimulating hormone (TSH) have thus far been ambiguous. Our aim was to evaluate the radioprotective effect of inhibiting the thyroid gland's activity during x-radiation. For this purpose, of 80 5-week old Wistar rats, 64 received cervical irradiation with 15 Gy (single dose). During irradiation, endocrine intervention was done, using thyroxine (T(4)), T(4) plus iodine, or iodine alone compared to placebo. During the endocrine interventions and follow-up, TSH and T(4) concentrations were measured periodically. Histologic examination of thyroid, pituitary gland, or the hypothalamus and any suspect lymph nodes, lungs, and liver was performed after 6 and 54 weeks. It was found that during the endocrine intervention, plasma levels of TSH were lower in rats given T(4) and higher in rats given iodine. After 6 and 54 weeks, no significant reduction in hypothyroidism or thyroid carcinoma was found between the different groups of rats given any endocrine intervention or no intervention. In conclusion, the administration of T(4), iodine or the combination during x-irradiation does not protect against radiation-induced thyroid damage.

Animals↗