Pediatric primary ciliary dyskinesia
Introduction
Introduction to primary ciliary dyskinesia in children Primary ciliary dyskinesia (PCD), also known as immobileciliasyndrome, is an autosomal recessive inheritance that causes repeated respiratory infections. Primary ciliary dyskinesia includes several types of ciliary immobility syndrome, Kartagener syndrome, ciliary dysplasia, and primary ciliary dysfunction. 50% of cases in the PCD were combined with visceral transposition to form Kartagener syndrome. basic knowledge The proportion of illness: 0.006% Susceptible people: children Mode of infection: non-infectious Complications: sinusitis, bronchitis, pneumonia, otitis media, extrauterine pregnancy, hydrocephalus
Cause
Causes of primary ciliary dyskinesia in children
Congenital anomalies (25%):
Primary ciliary immobility syndrome, cystic fibrosis, Young syndrome, abnormal cilia length, lack of cilia, short power arm, all or part of the lack, radiation axle defects and microtubule ectopic, etc. Congenital anomaly.
Disease factors (35%):
Local abnormalities are mostly secondary, chronic bronchitis, pneumonia, bronchiectasis, asthma and lung cancer can cause cilia vary in size, huge cilia; chronic sinusitis, asthma can cause axonal degeneration; viral infection can cause cilia to fall off, depression; Allergic rhinitis can cause cilia weakness; Mycoplasma pneumoniae secretes hydrogen peroxide, and Pseudomonas aeruginosa secretes pyocyanin to inhibit ciliary movement, smoking, environmental pollution, radiation, hydrogen sulfide, mechanical ventilation, etc. can cause dysfunction of clearing, Clinical diseases caused by cilia dysfunction are extensive and can involve all areas of cilia distribution, and respiratory tract infections caused by airway cilia dysfunction are the most common.
Sinusitis (20%):
Sperm flagella, vas deferens, tubal cilia dysfunction can lead to infertility or infertility; middle ear, sinus ciliary dysfunction leads to otitis media, sinusitis, etc.; retinal rod cells, vestibular hair cells and olfactory cell dysfunction lead to blindness, Deafness and dysosmia; there are also reports of hydrocephalus due to cilia dysfunction at the ependymal membrane of the brain and spinal cord.
Pathogenesis
Many parts of the human body have cilia or similar structures. The normal function of cilia is an important factor in maintaining the function of the organ, system and the whole body. The function of the normal airway mucus-ciliary transport system is of great significance for maintaining the defense function of the airway. The cilia structure is widely distributed in the respiratory tract, middle ear, fallopian tube, vas deferens, sperm flagella, and tissues and organs such as the brain and spinal cord epens. Due to abnormal structure and function of cilia, ciliary movement and clearing dysfunction can cause repeated sinusitis. , bronchitis, pneumonia, otitis media, ectopic pregnancy, infertility and hydrocephalus, etc., there are more than 20 kinds of ultrastructural abnormalities of cilia, mainly based on dynamic protein arm defects, microtubule defects, radiation wheel defects, Microtubules are arranged in disorder, and further cilia biopsy is needed to assist in diagnosis. Since the cilia structure is composed of at least 200 proteins and has a large number of potential genes, it is unlikely that genetic testing will be used as a diagnostic tool in a short period of time. Including: the presence of ciliated cells on the surface of the protein-powered arm, in the paranasal sinus, the eustachian tube, There are also cilia distributions. In addition, there are cilia structures in the fallopian tubes, sperm and brain and spinal cord epens. The distribution of cilia in the bronchus of the airway is different, with the most atmospheric channels, fewer small airways, alveolar sacs and alveoli. Without cilia structure, each ciliated cell has more than 200 cilia, cilia with a diameter of about 0.1-0.2 m and a length of about 3-7 m. Each cilia includes a body, a base and a crown, and the cross section is under electron microscope. It is round and has a pair of central microtubes in the center. It is evenly surrounded by 9 pairs of surrounding microtubules on the outer circumference. It is called a 92-axis microtubule structure (Fig. 1).
The respiratory system is an open organ and requires a complete decontamination mechanism to keep the system clean and stable. There is a layer of mucus on the cilia of the tracheobronchial epithelium called the cilia mucus blanket, and the mucociliary clearance (MCC) is One of the important respiratory clearance mechanisms, with mechanical, chemical and biological barriers. The MCC function is exerted by the cilia oscillation. The effective oscillation of the cilia is the result of effective sliding between the two tubes. This sliding is performed by the protein dynamic arm. The energy obtained during the ATP-driven mechanochemical conversion process, the cilia swing to remove the mucus is a cyclical process involving three states: resting state, recovery stroke and effective stroke throughout During the swinging process, the cilia first oscillates 180° backwards, close to the surface of the cell membrane and fully stretches, and then begins to effectively oscillate. The effective swing is performed on a plane perpendicular to the cell surface, swinging toward the head end, and the cilia is briefly silenced after the effective swing. The state of interest begins a new cycle, the fiber of the normal person's respiratory tract The roots are arranged in rows, and the direction of effective swaying of all cilia is basically the same, forming a combined force to push the surface mucus to move toward the head end. The cilia are carried out in a coordinated coordination manner, and each cilia and its adjacent cilia are sequentially swayed. When the cilia enters the recovery swing from the resting state and swings backward, it touches the cilia of other resting states and stimulates them to enter the recovery swing process. Therefore, the normal ciliary movement has the following three characteristics: 1. Periodicity and rhythm, 2 Directionality, 3. Synchronization, coordination and heterogeneity. Repeated infection is caused by adhesion and proliferation of local pathogenic microorganisms due to cilia clearance and dysfunction of the respiratory tract. However, the mechanism of visceral translocation is still inconclusive.
Prevention
Primary ciliary dyskinesia prevention in children
Strengthen the health care during pregnancy, actively prevent upper respiratory tract infection after birth, apply antibiotics in respiratory tract infections until full recovery, and make autoimmune such as measles and whooping cough. Antibiotics can be used to prevent infection during non-infectious period. Correct treatment can make patients have normal life. .
Complication
Pediatric primary ciliary dyskinesia complications Complications sinusitis bronchitis pneumonia otitis media ectopic pregnancy hydrocephalus
Can cause repeated sinusitis, bronchitis, pneumonia, otitis media, ectopic pregnancy, infertility and hydrocephalus.
Symptom
Primary ciliary dyskinesia symptoms in children Common symptoms Purulent secretions, purulent sputum, ear canal, pus, triple sign, hemoptysis, hearing loss, male infertility
The age of onset can range from infants to adults, but with school-age children and young people, repeated upper and lower respiratory tract infections with age, including recurrent otitis media, sinusitis and bronchitis, pneumonia caused by bronchiectasis, common ear canal flow Pus, nasal purulent secretions, cough, cough, hemoptysis, severe asthma, often misdiagnosed as general chronic bronchitis, chronic pneumonia, asthma and tuberculosis, common signs for cyanosis and clubbing, bronchial bronchial dilation The two lower leaves are the most common, followed by the left lung tongue and the right middle lobe. The shape is more common with columnar expansion, a few can be seen with cystic dilatation, sometimes with atelectasis and emphysema, hearing impairment, male infertility, etc. 50% of patients with right heart, Kartagener syndrome (Figure 3) consists of the following triads: 1. Bronchiectasis, 2. Sinusitis or nasal polyps, 3. Visceral transposition (mainly right heart), Familial.
Examine
Examination of primary ciliary dyskinesia in children
1. General examination: often infected with blood, hypoxemia, etc.
2. Electron microscopy: The diagnosis can be taken by nasal mucosa biopsy or bronchoscopy to take the bronchial mucosa epithelium under electron microscope to observe the number and structural abnormalities of cilia, so as to confirm the diagnosis, and the ability to check sperm motility is impaired.
3. Imaging examination: pulmonary inflammation, bronchitis, pneumonia, sinusitis, bronchiectasis, etc., sometimes with atelectasis and emphysema; bronchography or high-resolution CT can be seen in bronchiectasis with two lower leaves most common Second, the left lung tongue and the right middle lobe, the shape is more common with columnar expansion, a few can be seen cystic expansion, sometimes visible right heart,
4. Examination method of mucociliary clearance function: including saccharin screening test, radioactive aerosol inhalation lung scanning, scanning electron microscope combined with high-speed photography to measure the swaying frequency of cilia, and bronchoscopy combined with gamma photography to measure bronchial mucus transport speed.
Diagnosis
Diagnosis and diagnosis of primary ciliary dyskinesia in children
Diagnostic criteria
The incidence of human visceral inversion is about 1:1 to 1:5000, the common incidence of bronchiectasis is 0.3 to 0.5, and the incidence of bronchiectasis in patients with visceral inversion can be increased to 12% to 25 %, 40 to 50 times that of the average person. Therefore, if the right heart child has frequent sensation and pneumonia, it should be considered that there is a combination of bronchodilation and sinusitis, that is, the possibility of Kartagener syndrome, such as only visceral Position and bronchiectasis are incomplete Kartagener syndrome, Kartagener syndrome often coincides with other congenital malformations, the most common are congenital heart disease, hydrocephalus, cleft palate, bilateral neck ribs, anal atresia , hypospadias and kidney, other membranous pupils, mental retardation, hearing loss, olfactory defects, etc., the child has a history of repeated otitis media since the neonatal period, at present, the child still cough repeatedly, more Thick, yellow-green purulent, with bronchiectasis, combined with right heart, diagnosis is not difficult.
1. There are typical clinical manifestations of chronic, repeated respiratory infections, which may be accompanied by bronchiectasis. At the same time, there may be sinusitis, otitis media, male infertility, etc.; with visceral transposition, Kartagener syndrome should be considered, 2. Mucus The examination method of cilia removal function and electron microscopy can help confirm the diagnosis.
Differential diagnosis
1. Secondary ciliary dysfunction Primary ciliary dyskinesia should be differentiated from secondary ciliary columnar epithelial structure abnormalities, the latter secondary to infection, air pollution and other factors, structural changes are reversible, with composite cilia and micro Tube defects are common, secondary pilus columnar epithelial structure is abnormally late, and there are cases of repeated infection and irregular treatment. Therefore, it is better to carry out cilia biopsy after 4 to 6 weeks of anti-infection.
2. Cystic fibrosis should also be differentiated from cystic fibrosis (CF), which is more common in Caucasians and is also autosomal recessive, which can cause sinus and lung diseases. Male infertility, but its pathogenesis is abnormal mucous components, due to thick and difficult to be removed by cilia, pancreatic insufficiency and sweat test positive (increased sweat chlorine), its condition is relatively heavy.
