Clinico-pathological evaluation of ciliary dyskinesia: diagnostic role of electron microscopy

Transmission electron microscopy study of suspected primary ciliary dyskinesia patients

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive condition often presenting with chronic respiratory infections in early life. Transmission electron microscopy (TEM) is used to detect ciliary ultrastructural defects. In this study, we aimed to assess ciliary ultrastructural defects using quantitative methods on TEM to identify its diagnostic role in confirming PCD. Nasal samples of 67 patients, including 37 females and 30 males (20.3 ± 10.7 years old), with suspected PCD symptoms were examined by TEM. The most common presentations were bronchiectasis: 26 (38.8%), chronic sinusitis: 23 (34.3%), and recurrent lower respiratory infections: 21 (31.3%). Secondary ciliary dyskinesia, including compound cilia (41.4%) and extra-tubules (44.3%), were the most prevalent TEM finding. Twelve patients (17.9%) had hallmark diagnostic criteria for PCD (class 1) consisting of 11 (16.4%) outer and inner dynein arm (ODA and IDA) defects and only one concurrent IDA defect and microtubular disorganization. Also, 11 patients (16.4%) had probable criteria for PCD (class 2), 26 (38.8%) had other defects, and 18 (26.9%) had normal ciliary ultrastructure. Among our suspected PCD patients, the most common ultrastructural ciliary defects were extra-tubules and compound cilia. However, the most prevalent hallmark diagnostic defect confirming PCD was simultaneous defects of IDA and ODA.

Motile cilia defects in diseases other than primary ciliary dyskinesia: The contemporary diagnostic and research role for transmission electron microscopy

Ultrastructural studies have underpinned the cell biological and clinical investigations of the varied roles of motile cilia in health and disease, with a long history since the 1950s. Recent developments from transmission electron microscopy (TEM; cryo-electron microscopy, electron tomography) have yielded higher resolution and fresh insights into the structure and function of these complex organelles. Microscopy in ciliated organisms, disease models, and in patients with ciliopathy diseases has dramatically expanded our understanding of the ubiquity, multisystem involvement, and importance of cilia in normal human development. Here, we review the importance of motile cilia ultrastructural studies in understanding the basis of diseases other than primary ciliary dyskinesia.

Secondary defects detected by transmission electron microscopy in primary ciliary dyskinesia diagnostics

Primary ciliary dyskinesia (PCD) is predominantly an autosomal recessively inherited condition that affects ~1 in 15,000 people. Diagnosis of PCD can be complex and is ordinarily based on the results of multiple investigations. These investigations include nasal nitric oxide, high-speed video microscopy, genotyping, and electron microscopy analysis of ciliary ultrastructure. A diagnosis is ultimately confirmed by the presence of a hallmark defect identified by transmission electron microscopy or biallelic variants in a known PCD gene. Secondary ciliary defects are commonly seen in samples submitted for diagnosis of PCD. Acquired secondary ciliary ultrastructural abnormalities, which are not caused by a variant in a ciliary gene, are usually transient and reversible however failure to separate primary versus secondary defects can lead to misdiagnosis. In this review, we describe causes of secondary ciliary defects, identify the ultrastructural appearances associated with secondary ciliary dyskinesia and finally suggest methods to avoid misdiagnosis of PCD due to these acquired ciliary defects.

Nasal versus tracheobronchial biopsies to diagnose primary ciliary dyskinesia: A meta-analysis

OBJECTIVES/HYPOTHESIS

To systematically review the literature regarding the efficacy of different biopsy sites and methods to obtain an adequate ciliary sample for ultrastructural examination with electron microscopy (EM) for the diagnosis of primary ciliary dyskinesia (PCD).

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A literature search was conducted with respect to the diagnosis of PCD. English studies with five or more subjects were included. Successful biopsy was defined as an adequate ciliary sample to make or exclude the diagnosis of PCD.

RESULTS

Eight studies met inclusion criteria. These studies included 1,993 patients who underwent 2,299 ciliary biopsies. Included studies were level 3 or 4 evidence. The weighted pooled proportion of obtaining an adequate specimen from a nasal biopsy was 76% (95% confidence interval [CI], 64%-86%) versus 66% (95% CI, 62%-69%) for a tracheobronchial site (P = 0.10). The pooled proportion of obtaining an adequate sample was 68% for both brush and forceps biopsy groups (95% CI, 58%-77% and 54%-81%, respectively). Nasal scraping yielded a higher proportion of adequate specimens (pooled proportion of 92%; 95% CI, 82%-99%) than other techniques (P = 0.002).

CONCLUSION

Tissue biopsy is one component of diagnosing PCD. We found no significant difference between biopsy sites in terms of obtaining an adequate ciliary sample for EM evaluation. This suggests that nasal biopsy should be preferred for patients old enough to tolerate an office biopsy without the need for general anesthesia. The merits of nasal versus tracheobronchial biopsy in the operating room depend more on the risks and benefits of the procedure being performed.

LEVEL OF EVIDENCE

NA Laryngoscope, 127:6-13, 2017.

Impact of cilia ultrastructural examination on the diagnosis of primary ciliary dyskinesia

Ultrastructural examination of cilia is the "gold standard" for diagnosing primary ciliary dyskinesia. There is little evidence suggesting the most effective method of procuring a ciliary biopsy and scant benchmark data on rates of conclusive biopsies or on the diagnostic impact of such biopsies. To critically assess rates of inconclusive, positive, and negative ciliary biopsies and to identify clinical factors associated with conclusive results, we reviewed ciliary biopsies submitted for electron microscopy from 2006 to 2011, noting whether specimens were adequate for analysis and whether the ciliary structure was normal. The biopsy site, method used, procedurist's specialty, and clinical diagnoses were determined. Biopsy findings were categorized by diagnostic impact. Over 5 years, 187 patients had 211 biopsies. Conclusive results were obtained on 133/211 biopsies (63%); the remainder were insufficient. The rate of inconclusive biopsies did not vary significantly (P > 0.05; Fisher's exact) among sampling methods. Abnormal results were identified in 8/133 (6.0%) of the adequate specimens. Forceps compared to brush biopsies (abnormal in 4/12 versus 4/121 of the adequate specimens, P  =  0.002), along with multiple biopsy samples (taken on same or different days) compared with a single biopsy sample (abnormal in 3/12 versus 1/110 of the adequate specimens, P  =  0.01), were more likely to yield an abnormal result. Only 63% of pediatric ciliary biopsies provide adequate morphology for analysis, the large majority of these samples showing normal ciliary anatomy. The method of obtaining biopsies did not significantly affect result conclusiveness. Understanding the diagnostic impact of ultrastructural analysis is important as new diagnostic algorithms are developed for primary ciliary dyskinesia.

Diagnostic yield of nasal scrape biopsies in primary ciliary dyskinesia: a multicenter experience

Examination of ciliary ultrastructure remains the cornerstone diagnostic test for primary ciliary dyskinesia (PCD), a disease of abnormal ciliary structure and/or function. Obtaining a biopsy with sufficient interpretable cilia and producing quality transmission electron micrographs (TEM) is challenging. Methods for processing tissues for optimal preservation of axonemal structures are not standardized. This study describes our experience using a standard operating procedure (SOP) for collecting nasal scrape biopsies and processing TEMs in a centralized laboratory. We enrolled patients with suspected PCD at research sites of the Genetic Disorders of Mucociliary Clearance Consortium. Biopsies were performed according to a SOP whereby curettes were used to scrape the inferior surface of the inferior turbinate, with samples placed in fixative. Specimens were shipped to a central laboratory where TEMs were prepared and blindly reviewed. Four hundred forty-eight specimens were obtained from 107 young children (0-5 years), 189 older children (5-18 years), and 152 adults (> 18 years), and 88% were adequate for formal interpretation. The proportion of adequate specimens was higher in adults than in children. Fifty percent of the adequate TEMs showed normal ciliary ultrastructure, 39% showed hallmark ultrastructural changes of PCD, and 11% had indeterminate findings. Among specimens without clearly normal ultrastructure, 72% had defects of the outer and/or inner dynein arms (IDA), while 7% had central apparatus defects with or without IDA defects. In summary, nasal scrape biopsies can be performed in the outpatient setting and yield interpretable samples, when performed by individuals with adequate training and experience according to an SOP.

Ultrastructural abnormalities of respiratory cilia: a 25-year experience

CONTEXT

Ciliary dyskinesia is a rare, but significant, cause of chronic respiratory infections, and transmission electron microscopy is a critical adjunct to making the diagnosis.

OBJECTIVE

To investigate a single institution's experience with patients demonstrating abnormal ciliary ultrastructure.

DESIGN

Retrospective clinicopathologic review of 278 bronchial or nasal turbinate brushings or biopsies from 1983 through 2007.

RESULTS

There were 12 women and 9 men (mean age, 19.6 years; range, 1-54 years) with abnormal ciliary ultrastructure. Clinical history was unavailable in 3 patients, 15 (83%) of 18 patients presented with chronic or recurrent upper respiratory infections, and 3 (17%) presented with infertility. Seven (39%) of 18 patients had findings of Kartagener syndrome with situs inversus, dextrocardia, and bronchiectasis. Truncation or absence of inner or outer dynein arms occurred in 15 (71%) of 21 cases, and 5 (24%) revealed transposition defects with displacement of the central microtubules and peripheral doublets in 9 + 0 and 8 + 1 patterns. Radial spoke defects with microtubular disarray occurred in 4 (19%) of 21 cases. Compound cilia with multiple axonemes within a single outer sheath and supernumerary microtubules each occurred in 2 (10%) of the cases. Random ciliary orientation was also found in 2 (10%) of the cases, and dense granular basal body inclusions occurred in 1 case (5%). Multiple abnormalities occurred in 6 (29%) of the 21 cases.

CONCLUSIONS

Most patients presented with chronic respiratory tract infections or infertility. Dynein arm defects, transposition defects, and radial spoke defects were the most commonly encountered abnormal findings. Less-frequent abnormal findings included compound cilia, supernumerary microtubules, and dense granular basal body inclusions.

Aspiration, Bronchial Obstruction, Bronchiectasis, and Related Disorders

The conducting airways play a pivotal role in the spectrum of pulmonary pathology, not only as conduits for injurious agents to enter the lung, but also as an anatomic compartment that is affected by a diverse array of primary or secondary bronchocentric diseases. This chapter discusses aspiration and bronchial obstruction in detail, with emphasis on the aspiration of toxic, infective, or particulate matter. Lung abscess, a frequent complication of obstruction or aspiration, is also reviewed. Both aspiration and lung abscess are reconsidered within the context of pulmonary infectious disease mainly in Chapter 8 on bacterial infections, and to some extent in the chapters on mycobacterial (Chapter 9), fungal (Chapter 10), and parasitic diseases (Chapter 14).

Transmission electron microscopy in the diagnosis of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is an autosomal recessive disease with extensive genetic heterogeneity. Dyskinetic or completely absent motility of cilia predisposes to recurrent pulmonary and upper respiratory tract infections resulting in bronchiectasis. Also infections of the middle ear are common due to lack of ciliary movement in the Eustachian tube. Men have reduced fertility due to spermatozoa with absent motility or abnormalities in the ductuli efferentes. Female subfertility and tendency to ectopic pregnancy has also been suggested. Headache, a common complaint in PCD patients, has been associated with absence of cilia in the brain ventricles, leading to decreased circulation of the cerebrospinal fluid. Finally, half of the patients with PCD has situs inversus, probably due to the absence of ciliary motility in Hensen's node in the embryo, which is responsible for the unidirectional flow of fluid on the back of the embryo, which determines sidedness. PCD, which is an inborn disease, should be distinguished from secondary ciliary dyskinesia (SCD) which is an acquired disease. Transmission electron microscopy is the most commonly used method for diagnosis of PCD, even though alternative methods, such as determination of ciliary motility and measurement of exhaled nitric oxide (NO) may be considered. The best method to distinguish PCD from SCD is the determination of the number of inner and outer dynein arms, which can be carried out reliably on a limited number of ciliary cross-sections. There is also a significant difference in the ciliary orientation (determined by the direction of a line drawn through the central microtubule pair) between PCD and SCD, but there is some overlap in the values, making this parameter less suitable to distinguish PCD from SCD.

Ultrastructural patterns of primary ciliar dyskinesia syndrome

Clinical presentation, ciliary ultrastructure, and nasal mucociliary transport by a radioisotopic technique were analyzed in 14 Kartagener syndrome patients. In this study the most common pattern was the absence of outer and inner dynein arms in 57% of cases. Also reported are 14% patients with short inner dynein arms. A total of 29% of the patients showed normal dynein arms. Mucociliary stasis was observed in 13 cases. Primary ciliary dyskinesia syndrome and Kartagener syndrome are clinically homogeneous and morphologically heterogeneous. The authors conclude that a typical clinical presentation with an altered mucociliary transport obtained by radioisotopic technique is diagnostic although ciliary ultrastructure is normal.

[Study of mucociliary transport and nasal ciliary ultrastructure in patients with Kartagener's syndrome]

OBJECTIVE

Kartagener's syndrome (KS) is a clinical variant of primary ciliary dyskinesia involving situs inversus associated with chronic airway infections. The ciliary defect associated with this syndrome is the absence of dynein arms. The aim of this study was to evaluate mucociliary transport and ciliary ultrastructure in 14 patients with KS.

PATIENTS AND METHODS

We studied nasal mucociliary transport using a radioisotopic technique and ciliary ultrastructure in 14 patients with KS.

RESULTS

Thirteen patients had mucociliary stasis and 1 had severely slowed transport (1.3 mm/min). Four patients (29%) had cilia with normal dynein arms, 2 patients (14%) had short inner dynein arms, and 8 patients (57.1%) had total absence of inner and outer dynein arms.

CONCLUSIONS

We conclude that the typical clinical presentation, together with altered mucociliary transport as identified by an isotopic technique, is diagnostic of KS, even when the ciliary ultrastructure is normal. KS is clinically homogenous and morphologically heterogenous.