In this thesis we describe the genetic, biochemical and clinical characteristics of patients with head and neck paragangliomas (HNPGL). In the Netherlands, the majority of SDHx mutation carriers,... Show moreIn this thesis we describe the genetic, biochemical and clinical characteristics of patients with head and neck paragangliomas (HNPGL). In the Netherlands, the majority of SDHx mutation carriers, harbor a mutation in the SDHD gene. Twenty-nine percent of patients with HNPGL have increased urinary excretion of 3-methoxytyramine, indicating dopaminergic activity. Test sensitivity of plasma 3MT measurement equals the measurement of urinary deconjugated 3MT excretion. Only a minority of HNPGL patients have increased plasma chromogranin A levels. Therefore, the practical implications of the measurement of plasma chromogranin A levels are limited in HNPGL patients. Patients screened for pheochromocytomas, because of a hereditary predisposition, present with less signs and symptoms, lower urinary excretion rates of catecholamines, and smaller tumors than patients presenting with symptomatic pheochromocytomas. Despite these differences in biochemical activity and the sizes of the tumors, there is no difference in patients regarding peri-operative complications. Patients with bilateral carotid body tumors are at risk for developing sleep disordered breathing. Sleep disordered breathing is associated with increased carotid body output, which is reflected by increased chemosensitivity. Show less
