What does elevation of the left hemidiaphragm (left half of the diaphragm) indicate on a chest x-ray (chest radiograph)?

From the Guidelines

Elevation of the left hemidiaphragm on a chest x-ray is a significant finding that requires further investigation to determine the underlying cause, which can include phrenic nerve paralysis, subphrenic abscess, gastric distention, splenic enlargement, or left lung volume loss. This finding can be caused by several conditions, including phrenic nerve paralysis, subphrenic abscess, gastric distention, splenic enlargement, or left lung volume loss (such as from atelectasis or previous lung surgery) 1. When evaluating this finding, it's essential to consider the patient's clinical symptoms, medical history, and other radiographic findings. The normal difference between the right and left hemidiaphragm is typically 1-2 cm, with the right side normally higher due to the liver beneath it. If the elevation is new or significant (greater than 4 cm difference between sides), further investigation with additional imaging such as ultrasound, CT scan, or fluoroscopic sniff test (to assess diaphragmatic movement) may be warranted to determine the underlying cause 1. Some key radiological findings that may be associated with diaphragmatic hernia include diaphragmatic discontinuity, segmental non-recognition of the diaphragm, “Dangling diaphragm” sign, “Dependent viscera” sign, intrathoracic herniation of abdominal contents, “Collar sign”, contiguous injuries of both sides of the diaphragm, elevated abdominal organs, thickened diaphragm, thoracic fluid, abutting intra-abdominal viscera, hypo-attenuated hemidiaphragm and associated fractured ribs 1. Asymptomatic patients with chronic or mild elevation may not require treatment, while symptomatic cases would be managed by addressing the underlying condition. Key points to consider in the management of patients with elevated left hemidiaphragm include:

• Clinical symptoms and medical history
• Radiographic findings, including the degree of elevation and associated abnormalities
• Need for further imaging, such as CT scan or fluoroscopic sniff test
• Potential underlying causes, such as phrenic nerve paralysis or diaphragmatic hernia
• Management of symptomatic cases, including treatment of the underlying condition.

From the Research

Elevation of the Left Hemidiaphragm on Chest X-Ray

• The elevation of the left hemidiaphragm on a chest x-ray, in the absence of an ipsilateral lung disease, is assumed to indicate severe hemidiaphragm dysfunction 2.
• However, the study found that chest radiographs have limited value in diagnosing unilateral diaphragm dysfunction, with a sensitivity of 0.90 and specificity of 0.44 2.
• Other studies suggest that non-invasive measurements of phrenic nerve conduction time and diaphragmatic electromyographic response to voluntary inspiratory efforts may help to document an abnormal diaphragmatic function in the presence of hemidiaphragm elevation on chest radiographs 3.
• Phrenic nerve conduction study (NCS) is a simple, reproducible, noninvasive method that correlates well with transdiaphragmatic pressure (Pdi) measurements and provides insight into the mechanism of unilateral diaphragmatic paralysis 4.
• The diagnosis of unilateral diaphragmatic paralysis should be considered in patients with dyspnea, especially if it worsens when lying down, and paradoxical respiration may be present 5.

Diagnostic Approaches

• Phrenic nerve conduction studies and electromyography may provide evidence of bilateral involvement in patients with suspected diaphragmatic paralysis 5.
• Combining lung function tests, respiratory muscle assessments, and phrenic NCS can help establish the diagnosis of unilateral diaphragmatic paralysis in difficult cases 4.
• Electrodiagnostic testing, such as phrenic nerve conduction studies, can aid in determining the most effective therapy for patients with symptomatic diaphragmatic paralysis 6.