The diagnosis of symptomatic hemidiaphragm paralysis or eventration is primarily clinical, and relies mostly on history, chest x-ray, and the physician's clinical acuity.
The evaluation of a symptomatic patient with diaphragmatic paralysis or eventration should include an objective assessment of dyspnea, physical examination, PFTs, and imaging studies.
Careful history taking about the duration and progression of dyspnea and orthopnea is critical. Any additional causes of dyspnea (e.g., morbid obesity, primary lung disease, heart failure) should be investigated and corrected if possible, since dyspnea secondary to diaphragmatic paralysis or eventration is mainly a diagnosis of exclusion.
All patients with dyspnea secondary to an elevated hemidiaphragm eventration should fill out a standardized respiratory questionnaire to more objectively evaluate the severity of their symptoms and to assess the response to treatment.
PFTs provide certain objectivity to the assessment of dyspneic patients with an elevated hemidiaphragm; however, PFTs are imprecise and do not correlate well with severity of dyspnea or response to plication. Since diaphragm dysfunction reduces the compliance of the chest wall, a restrictive pattern (i.e., low forced vital capacity [FVC] and forced expiratory volume in 1 second [FEV1]) is often seen.4
The diaphragm is a critical mediator of inspiration; therefore, assessing inspiratory PFT parameters (e.g., maximum forced inspiratory flow [FIFmax]) is important.
In addition, FVC should be assessed in the upright and supine position. Supine FVC in healthy individuals can decrease up to 20% from upright values, and supine lung volumes may decrease by 20% to 50% in patients with diaphragmatic eventration or paralysis.
On a standard full-inspiration PA/LAT chest x-ray, the right hemidiaphragm is normally 1 to 2 cm higher than the left. Hemidiaphragm elevation can be a sign of diaphragmatic paralysis or paralysis; however, this is a nonspecific finding since a variety of pulmonary, pleural, and subdiaphragmatic processes can also cause elevation of the hemidiaphragm. Consequently, further studies may be needed if an elevated hemidiaphragm is noted on a chest x-ray in the presence of dyspnea.
The clinical value of a sniff test is limited in the presence of an elevated diaphragm and dyspnea. The principal role of the sniff test is to help discern the etiology of dyspnea in patients with a less evident primary cause of dyspnea.
During fluoroscopy, patients are instructed to sniff, and diaphragmatic excursion is assessed. Normally, the diaphragm moves caudally. In patients with hemidiaphragmatic paralysis, the diaphragm may (paradoxically) move cranially. Patients with diaphragmatic eventration, however, may also exhibit passive upward movement of the diaphragm when sniffing.
Fluoroscopy findings should be interpreted with caution. First, about 6% of normal individuals exhibit paradoxical motion on fluoroscopy; to increase the specificity of this study, at least 2 cm of paradoxical motion should be noticed. Second, a paralyzed or eventrated hemidiaphragm may move very little or not at all, without paradoxical motion, making the interpretation of the sniff test and the distinction between paralysis and eventration even more challenging.4
The principal utility of computed tomography (CT) scans is to exclude the presence of a cervical or intrathoracic tumor as the cause of phrenic nerve paralysis or to evaluate the possibility of a subphrenic process as the cause of hemidiaphragm elevation. However, a CT scan is not routinely required if the clinical suspicion of an alternate process is low.
Other diagnostic tests such as ultrasonography, dynamic magnetic resonance imaging, maximal transdiaphragmatic pressure, and phrenic nerve conduction studies are of limited or no value for the clinical evaluation of a dyspneic patient with an elevated hemidiaphragm.4
Potential candidates for laparoscopic diaphragm plication have an elevated hemidiaphragm and dyspnea; the minimal clinical assessment for plication should include history and physical examination, evaluation of the severity of dyspnea with a standardized respiratory quality-of-life questionnaire, a PA/LAT chest x-ray, and PFTs. Fluoroscopic sniff test and CT scan are of value in selected patients.