Neuromuscular diseases may involve all major respiratory muscles groups including inspiratory, expiratory, and bulbar muscles. Respiratory complications are the major cause of morbidity and mortality. Pneumonia represents a frequent cause of morbidity in children with neuromuscular disease. The aim of this review is to collect knowledge about pneumonia in children with neuromuscular diseases. Pneumonia usually follows viral respiratory infections of the upper respiratory tract, due to the combination of an increased amount of nasal and oral secretions and an impairment of the cough efficiency and of the clearance of secretions due to the muscle weakness, further compromised by the infection itself. The accumulation of bronchial secretions leads to atelectasis and promote bacterial infection. Moreover, dysfunction of swallowing mechanism exposes these children to the risk of developing aspiration pneumonia. However, etiology of viral and bacterial respiratory infection in these patients is still poorly studied. Moreover, dysfunction of swallowing mechanism exposes these children to the risk of developing aspiration pneumonia. However, etiology of viral and bacterial respiratory infection in these patients is still poorly studied. Keywords: neuromuscular disease, SMA, duchene muscular dystrophy, pneumonia, atelectasia status released display-pdf yes is-olf no is-manuscript no is-preprint no is-journal-matter no is-scanned no is-retracted no Received 2020 Nov 3; Accepted 2021 Aug 4; Collection date 2021. Introduction Neuromuscular diseases (NMD) may involve most respiratory muscles groups including inspiratory, expiratory, and bulbar. Respiratory complications are the major cause of morbidity and mortality. The natural course of NMD is characterized by ineffective cough and swallowing disorders leading to chronic aspiration, poor secretion clearance, pneumonia and hypercapnic respiratory failure. Pneumonia represents a frequent cause of morbidity in children with NMD; inhalation, impaired cough and atelectasis are the main risk factors. However, scarce literature investigating on pneumonia in children with NMD is available. This is caused by the presence of reduced inspiratory muscle strength, thoracic scoliosis and reduced chest wall and pulmonary compliance. Usually, inspiratory and expiratory muscle strength are equally impaired, however in SMA the diaphragm strength may be preserved and expiratory muscle weakness may prevail ( 4 ). Progressive neuromuscular weakness can lead to the inability to take deep breaths and to cough effectively ( 5 ). Cough efficacy can be measured by cough peak flow: reduced cough power is defined by values <270 L/min in children, and values <160 L/min are associated with high risk of atelectasis and pneumonia ( 6 ). Children with NMD are particularly prone to develop segmental or lobar atelectasis due to the retention of bronchial secretions. This is particularly evident in the lower lung zones, which may already be compressed by scoliosis or by the heart. They are also at risk for developing widespread, radiographically inapparent micro-atelectasis ( 8 ). The appearance of atelectasis exposes these patients to a higher risk of bacterial lung superinfections ( 9 ). Children presenting swallowing disorders, ineffective cough, atelectasis and capacity vital forced (FVC) <50% of predicted value are at high risk of pneumonia and should be trained in protocols that allow successful home treatment of respiratory exacerbations, performed by well-trained parents or healthcare professionals ( 10 , 11 ). Risk factors, pathophysiology and treatment of respiratory exacerbations and pneumonia in patients with NMD are shown in Figure 1 . Figure 1 Pathophysiology, clinical management and treatment of respiratory exacerbations/pneumonia in NMD. Community-Acquired Pneumonia As specified before, pneumonia in children with NMD usually follows viral respiratory infections ( 12 ). Generally, respiratory syncytial virus (RSV) infection predominates in infants, while rhinovirus, influenza and parainfluenza virus infections are common in children and adolescents ( 2 ). The risk of serious pulmonary complications associated to RSV infection led the American Academy of Pediatrics to introduce NMDs in the list of diseases requiring RSV immuno-prophylaxis ( 9 ). However, scarce literature investigating on microbiologic etiology of both viral and bacterial pneumonia in children with NMD is available ( 12 ). Aspiration Pneumonia Children with NMD show swallowing dysfunction that increases as muscle weakness progresses, and in some conditions such as SMA type 1 and severe forms of nemaline myopathy may present from early infancy ( 2 ). Difficulties in swallowing, resulting from loss of control of the larynx and pharynx, associated to ineffective cough predispose to aspiration lung disease ( 2 ). Aspirated material includes saliva, mouth organisms and food in children orally fed ( 2 ). Gastric contents may be aspirated if gastro-esophageal reflux is present. Aspiration causes inflammation of the lung parenchima and obstruction of the lower airways, leading to worsening restrictive lung disease, Kooi-van Es. et al. ( 14 ) demonstrated that the overall prevalence of dysphagia, in a large group of children with NMD was 47.2% ( 13 ). Although oral and pharyngeal weakness can The pathophysiology of respiratory exacerbations in patients with NMD is deeply understood. Pneumonia usually follows viral respiratory infections of the upper respiratory tract, due to the combination of an increased amount of nasal and oral secretions and an impairment of the cough efficiency and of the clearance of secretions due to the muscle weakness, further compromised by the infection itself. The accumulation of bronchial secretions leads to atelectasis and promote bacterial infection. Moreover, dysfunction of swallowing mechanism exposes these children to the risk of developing aspiration pneumonia.