Electron microscopy in ciliary disorders.

Primary ciliary dyskinesia (PCD) is composed of the diseases resulting from congenital defects of cilia. Diagnosis is reached on the basis of clinical history, abnormal ciliary beat frequency and specific axonemal defects observed by transmission electron microscopy. Electron microscopic assessment for the diagnosis of PCD comes into prominence in clinically and light microscopically undiagnosed cases. Microtubule defects, dynein arm deficiency and orientation disorders cannot be detected by light microscopy; electron microscopy is the method of choice in the diagnosis of such disorders. Ciliary orientation should be measured in patients having recurrent respiratory tract infections since disorientation can be the only defect in some patients. Ciliary disorders are classified as primary (congenital) and secondary (acquired) disorders. The latter are caused by environmental factors, such as infection, smoking and air pollution. The diagnosis of PCD may be difficult since the epithelial cell and ciliary defects can also be caused by acquired factors. Therefore, it is important to distinguish between primary and secondary structural and functional disorders. Electron microscopic analysis is the only option for diagnosing ultrastructural defects. Electron microscopic assessment in diagnosing PCD should be carried out only after excluding other probable causes of respiratory tract infections and after the appropriate treatment of infections responsible for secondary ciliary defects. In this manner, falsepositive diagnosis of PCD and high cost can be prevented. [ABSTRACT FROM AUTHOR]