Stereotactic radiosurgery for arteriovenous malformations
Nicholas C. Bambakidis and Warren R. Selman
Warren R. Selman and H. Richard Winn
Vivek Bansal, Nadine El Asmar, Warren R. Selman and Baha M. Arafah
Despite many recent advances, the management of patients with Cushing's disease continues to be challenging. Cushing's syndrome is a complex metabolic disorder that is a result of excess glucocorticoids. Excluding the exogenous causes, adrenocorticotropic hormone–secreting pituitary adenomas account for nearly 70% of all cases of Cushing's syndrome. The suspicion, diagnosis, and differential diagnosis require a logical systematic approach with attention paid to key details at each investigational step. A diagnosis of endogenous Cushing's syndrome is usually suspected in patients with clinical symptoms and confirmed by using multiple biochemical tests. Each of the biochemical tests used to establish the diagnosis has limitations that need to be considered for proper interpretation. Although some tests determine the total daily urinary excretion of cortisol, many others rely on measurements of serum cortisol at baseline and after stimulation (e.g., after corticotropin-releasing hormone) or suppression (e.g., dexamethasone) with agents that influence the hypothalamic-pituitary-adrenal axis. Other tests (e.g., measurements of late-night salivary cortisol concentration) rely on alterations in the diurnal rhythm of cortisol secretion. Because more than 90% of the cortisol in the circulation is protein bound, any alteration in the binding proteins (transcortin and albumin) will automatically influence the measured level and confound the interpretation of stimulation and suppression data, which are the basis for establishing the diagnosis of Cushing's syndrome. Although measuring late-night salivary cortisol seems to be an excellent initial test for hypercortisolism, it may be confounded by poor sampling methods and contamination. Measurements of 24-hour urinary free-cortisol excretion could be misleading in the presence of some pathological and physiological conditions. Dexamethasone suppression tests can be affected by illnesses that alter the absorption of the drug (e.g., malabsorption, celiac disease) and by the concurrent use of medications that interfere with its metabolism (e.g., inducers and inhibitors of the P450 enzyme system). In this review, the authors aim to review the pitfalls commonly encountered in the workup of patients suspected to have hypercortisolism. The optimal diagnosis and therapy for patients with Cushing's disease require the thorough and close coordination and involvement of all members of the management team.
John D. Carmichael, Gabriel Zada and Warren R. Selman
Meg Verrees, Baha M. Arafah and Warren R. Selman
Pituitary tumor apoplexy is an uncommon event heralded by abrupt onset of severe headache, restriction of visual fields, deterioration of visual acuity, and weakness of ocular motility frequently coupled with clinical indications of decreased endocrine function. Hemorrhage into or necrosis of a preexisting sellar mass, usually a pituitary macroadenoma, produces an expansion of sellar contents. Compression of adjacent structures elicits the variable expression of symptoms referable to displacement of the optic nerves and chiasm and impingement of the third, fourth, and sixth cranial nerves. Damage to or destruction of the anterior pituitary leads to multiple acute and/or chronic hormone deficiencies in many patients. Medical management may be used in rare cases in which the signs and symptoms are mild and restricted to meningismus or ophthalmoplegia deemed to be stable. In patients with visual or oculomotor lability or an altered level of consciousness, expeditious surgical decompression, accomplished most commonly through a transsphenoidal approach, should be performed to save life and vision and to optimize the chance of regaining or maintaining pituitary function.