Diaphragm: Pathophysiology and Ultrasound Imaging in Neuromuscular Disorders (original) (raw)
Related papers
Neuromuscular ultrasound for evaluation of the diaphragm
Muscle & Nerve, 2013
Neuromuscular clinicians are often asked to evaluate the diaphragm for diagnostic and prognostic purposes. Traditionally, this evaluation is accomplished through history, physical exam, fluoroscopic sniff test, nerve conduction studies, and electromyography (EMG). Nerve conduction studies and EMG in this setting are challenging, uncomfortable, and can cause serious complications such as pneumothorax. Neuromuscular ultrasound has emerged as a non-invasive technique that can be used in the structural and functional assessment of the diaphragm. This article reviews different techniques for assessing the diaphragm using neuromuscular ultrasound and the application of these techniques to enhance diagnosis and prognosis by neuromuscular clinicians.
Imaging of the Diaphragm: Anatomy and Function
RadioGraphics, 2012
The diaphragm is the primary muscle of ventilation. Dysfunction of the diaphragm is an underappreciated cause of respiratory difficulties and may be due to a wide variety of entities, including surgery, trauma, tumor, and infection. Diaphragmatic disease usually manifests as elevation at chest radiography. Functional imaging with fluoroscopy (or ultrasonography or magnetic resonance imaging) is a simple and effective method of diagnosing diaphragmatic dysfunction, which can be classified as paralysis, weakness, or eventration. Diaphragmatic paralysis is indicated by absence of orthograde excursion on quiet and deep breathing, with paradoxical motion on sniffing. Diaphragmatic weakness is indicated by reduced or delayed orthograde excursion on deep breathing, with or without paradoxical motion on sniffing. Eventration is congenital thinning of a segment of diaphragmatic muscle and manifests as focal weakness. Treatment of diaphragmatic paralysis depends on the cause of the dysfunction and the severity of the symptoms. Treatment options include plication and phrenic nerve stimulation. Supplemental material available at http://radiographics .rsna.org/lookup/suppl/
Diaphragmatic dysfunction in neuromuscular disease, an MRI study
Neuromuscular Disorders, 2021
The aim of this exploratory study was to evaluate diaphragmatic function across various neuromuscular diseases using spirometry-controlled MRI. We measured motion of the diaphragm relative to that of the thoracic wall (cranial-caudal ratio vs. anterior posterior ratio; CC-AP ratio), and changes in the diaphragmatic curvature (diaphragm height and area ratio) during inspiration in 12 adults with a neuromuscular disease having signs of respiratory muscle weakness, 18 healthy controls, and 35 adult Pompe patients-a group with prominent diaphragmatic weakness. CC-AP ratio was lower in patients with myopathies (n = 7, 1.25 ±0.30) and motor neuron diseases (n = 5, 1.30 ±0.10) than in healthy controls (1.37 ±0.14; p = 0.001 and p = 0.008), but not as abnormal as in Pompe patients (1.12 ±0.18; p = 0.011 and p = 0.024). The mean diaphragm height ratio was 1.17 ±0.33 in patients with myopathies, pointing at an insufficient diaphragmatic contraction. This was also seen in patients with Pompe disease (1.28 ±0.36), but not in healthy controls (0.82 ±0.33) or patients with motor neuron disease (0.82 ±0.24). We conclude that spirometry-controlled MRI enables us to investigate respiratory dysfunction across neuromuscular diseases, suggesting that the diaphragm is affected in a different way in myopathies and motor neuron diseases. Whether MRI can also be used to evaluate progression of diaphragmatic dysfunction requires additional studies.
Two-dimensional ultrasound imaging of the diaphragm: Quantitative values in normal subjects
Muscle & Nerve, 2013
Introduction: Real time ultrasound imaging of the diaphragm is an under-used tool in the evaluation of patients with unexplained dyspnea or respiratory failure. Methods: We measured diaphragm thickness and the change in thickness that occurs with maximal inspiration in 150 normal subjects, with results stratified for age, gender, body mass index, and smoking history. Results: The lower limit of normal diaphragm thickness at end expiration or functional residual capacity is 0.15 cm, and an increase of at least 20% in diaphragm thickness from functional residual capacity to total lung capacity is normal. A side to side difference in thickness at end expiration of > 0.33 cm is abnormal. Diaphragm thickness and contractility are minimally affected by age, gender, body habitus, or smoking history. Conclusions: This study confirms previous findings in much smaller groups of normal controls for quantitative ultrasound of the diaphragm and provides data that can be applied widely to the general population. 47: 884-889, 2013 Diaphragm dysfunction is an uncommon and fre-Abbreviations: EMG, electromyography; BMI, body mass index; COPD, chronic obstructive pulmonary disease
Ultrasound for assessment of diaphragm in ALS
Clinical Neurophysiology, 2016
h i g h l i g h t s Evaluation of diaphragm thickness at the apposition zone by ultrasound is a simple and well tolerated investigation in ALS patients. The measurement of diaphragm thickness at the apposition zone in ALS patients is significantly correlated with the amplitude of the motor response by electric phrenic nerve stimulation. Diaphragm thickness is independently correlated to maximal voluntary ventilation and forced vital capacity, which suggests that it gives important clinical information. a b s t r a c t Objective: To evaluate the correlation between diaphragm thickness assessed by ultrasound (US) with respiratory function tests and the diaphragm motor responses, in patients with amyotrophic lateral sclerosis (ALS). Methods: 42 consecutive ALS patients were studied (11 with bulbar-onset), excluding patients with marked orofacial paresis. Investigation included: revised ALS functional rating scale (ALSFRS-R), forced vital capacity (FVC), maximal voluntary ventilation (MVV), maximal inspiratory (MIP) and expiratory (MEP) pressures, nasal inspiratory pressure during sniff (SNIP); peak-to-peak amplitude of the diaphragmatic motor response to phrenic nerve stimulation (Diaphragm-CMAP), diaphragmatic thickness measured by ultrasound during maximal inspiration and during maximal expiration. Patients were analysed in bulbar or spinal subgroups. Correlations and multiple linear regression models were studied. Results: The mean age at disease onset was 58.4 ± 11.1 years and with a mean disease duration of 17.8 ± 13.6 months. Ultrasound studies of diaphragm thickness in full inspiration correlated with diaphragm CMAP in the whole population and in spinal-onset patients; and were similar in the two groups. Multiple linear modelling showed that FVC, SNIP and MVV were dependent on the change of thickness (p = 0.001, 0.001 and 0.020, respectively) and that MIP and MEP were related to diaphragm CMAP p = 0.003 and p = 0.025, respectively). Conclusion: Diaphragm thickness correlates with Diaphragm-CMAP, except in bulbar-onset patients. Respiratory tests are dependent on both diaphragm thickness and Diaphragm-CMAP. Significance: US thickness of the diaphragm correlates with the number of functional motor units as assessed by the phrenic nerve motor amplitude.
Ultrasonographic findings of the normal diaphragm: thickness and contractility
Annals of Clinical Neurophysiology, 2017
The diaphragm is the major muscle of respiration and its dysfunction is associated with problems ranging from orthopnea to prolonged recovery from surgery or ventilator management. Common causes of diaphragm dysfunction include phrenic neuropathy, motor neuron disease, neuromuscular junction disorders, and myopathy. 1-3 Although there are several diagnostic tests available for evaluating the diaphragm, each of them has limitations. 4,5 Chest x-rays are relatively insensitive. Fluoroscopy is difficult to quantitate, and, like computed tomography, involves radiation exposure and transportation need. Magnetic resonance imaging presents challenges for patients in the intensive care unit and
Functional evaluation of the diaphragm with a noninvasive test
Journal of Osteopathic Medicine, 2021
Cardiac surgery with median sternotomy causes iatrogenic damage to the function of the diaphragm muscle that is both temporary and permanent. Myocardial infarction itself causes diaphragmatic genetic alterations, which lead the muscle to nonphysiological adaptation. The respiratory muscle area plays several roles in maintaining both physical and mental health, as well as in maximizing recovery after a cardiac event. The evaluation of the diaphragm is a fundamental step in the therapeutic process, including the use of instruments such as ultrasound, magnetic resonance imaging (MRI), and computed axial tomography (CT). This article reviews the neurophysiological relationships of the diaphragm muscle and the symptoms of diaphragmatic contractile dysfunction. The authors discuss a scientific basis for the use of a new noninstrumental diaphragmatic test in the hope of stimulating research.
PLOS ONE
Background In patients with neuromuscular disorders, assessment of respiratory function relies on forced vital capacity (FVC) measurements. Providing complementary respiratory outcomes may be useful for clinical trials. Diaphragm sniff ultrasound (US) is a noninvasive technique that can assess diaphragm function that may be affected in patients with neuromuscular disorders. Purpose We aimed to provide normal values of sniff diaphragm ultrasound, to assess the relationship between sniff diaphragm US, vital capacity (VC) and sniff nasal pressure. Additionally, we aimed to evaluate the diagnostic accuracy of sniff diaphragm US for predicting restrictive pulmonary insufficiency. Materials and methods We included patients with neuromuscular disorders that had been tested with a sniff diaphragm US and functional respiratory tests. Healthy subjects were also included to obtain
Ultrasonographic Evaluation of Diaphragmatic Motion
To evaluate the technical feasibility and utility of ultrasonography in the study of diaphragmatic motion at our institution. Methods. The study consisted of 2 parts. For part I, in 23 volunteers we performed 23 studies on 46 hemidiaphragms with excursions documented on M-mode ultrasonography. For part II, in 22 patients we performed 52 studies in 102 hemidiaphragms. In 50 studies both hemidiaphragms were studied, and in another 2 studies only 1 hemidiaphragm was studied. Patients' ages ranged from birth to 66 years (mean, 23 years). There were 16 male and 6 female patients. Indications for the study were (1) suggestion of paralysis of the diaphragm (n = 22); (2) if the diaphragm was already known to be paralyzed, for evaluation of response to phrenic nerve or pacer stimulation (n = 9); and (3) follow-up of previous findings (n = 21). Patients were examined in the supine position in the longitudinal semicoronal plane from a subcostal or low intercostal approach. Motion was documented with real-time ultrasonography and measured with M-mode ultrasonography. Results. Of the 102 clinical hemidiaphragms studied, findings included normal motion (n = 42), decreased motion (n = 22), no motion (n = 6), paradoxical motion (n = 10), positive pacer response (n = 13), negative pacer response (n = 2), positive phrenic stimulation (n = 6), and negative phrenic stimulation (n = 1). There were no failures of visualization. Conclusions. Ultrasonography proved feasible and useful in evaluating diaphragmatic motion. In our practice it has replaced fluoroscopy. Ultrasonography has advantages over traditional fluoroscopy, including portability, lack of ionizing radiation, visualization of structures of the thoracic bases and upper abdomen, and the ability to quantify diaphragmatic motion.
The Area method: a new method for ultrasound assessment of diaphragmatic movement
Critical Ultrasound Journal
Background: Ultrasound can be used to assess diaphragm movement. Existing methods focus on movement at a single point at the hemidiaphragm and may not consider the anatomic and functional complexity. We aimed to develop an ultrasound method, the Area method, to assess movement of the entire hemidiaphragm dome and to compare it with existing methods to evaluate accuracy, inter-rater agreement, and feasibility. Methods: Movement of the diaphragm was evaluated by ultrasonography in 19 healthy subjects and correlated with simultaneously performed spirometry. Two existing methods, the M-mode excursion at the posterior part of diaphragm and the B-mode at the top of the diaphragm, were compared with the Area method. Two independent raters reviewed film clips to analyze inter-rater agreement. Feasibility was tested by novice ultrasound operators. Results: Correlation with expired lung volume was higher with the Area method, 0.88 (95% CI 0.81-0.95), p < 0.001, and with the M-mode measurement, 0.84 (95% CI 0.75-0.92), p < 0.001, than with the B-mode measurement, 0.71 (95% CI 0.59-0.83), p < 0.001. Inter-rater agreement was highest with the Area method, 0.9, p < 0.001, and M-mode measurement 0.9, p < 0.001, and lower with the B-mode measurement, 0.8, p < 0.001. The M-mode measurement could be done in only 20% at the left side. The Area method could be performed in all participants at both hemidiaphragms, and novice operators found it easy to perform. Conclusion: A new method to evaluate diaphragm movement is introduced. Accuracy and inter-rater agreement are high. The Area method is equally feasible at both hemidiaphragms in contrast to existing methods. However, additional studies should include more participants, different types of pulmonary diseases, and investigate the role of patient position to validate the Area method fully.