What causes an elevated right hemidiaphragm (HD) on X-ray in a patient who has suffered a stroke?

Causes of Elevated Right Hemidiaphragm on X-ray in Stroke Patients

The most common cause of an elevated right hemidiaphragm on X-ray in a stroke patient is hemidiaphragmatic paralysis or weakness contralateral to the cerebral lesion (typically from a left hemisphere stroke), which can lead to respiratory dysfunction and potential complications including atelectasis and pneumonia. 1, 2

Pathophysiological Mechanisms

• Stroke can affect the central pathways controlling diaphragmatic function, leading to weakness or paralysis of the hemidiaphragm contralateral to the brain lesion 2
• Internal capsule and complete middle cerebral artery (MCA) infarctions are major risk factors for developing diaphragmatic palsy, though it can occur with subcortical MCA infarctions without capsular involvement 2
• Studies show that maximal excursion of the diaphragm may be reduced bilaterally in acute stroke patients, with more significant weakness on the side contralateral to the brain lesion 3

Clinical Manifestations and Complications

• Hemidiaphragmatic weakness may present with:

  • Shortness of breath and orthopnea 1
  • Rapid, shallow breathing 4
  • Paradoxical inward motion of the abdomen during inspiration 4

• Complications that may develop include:

  • Persistent atelectasis of the lung base on the affected side 1
  • Inadequate alveolar ventilation 1
  • Development of basal pneumonia 1
  • Hypercapnic respiratory failure in severe cases 1

Radiographic Findings

• Chest X-ray typically shows an elevated hemidiaphragm on the affected side 1, 5
• Fluoroscopic examination may confirm decreased movements of the affected hemidiaphragm 5
• Additional imaging may show associated atelectasis or pneumonia in the lung base 1

Other Potential Causes of Elevated Hemidiaphragm in Stroke Patients

• Respiratory complications of stroke that may contribute to diaphragmatic elevation:

  • Aspiration pneumonia (common in patients with dysphagia or decreased level of consciousness) 6
  • Atelectasis (particularly in immobilized patients) 6
  • Pulmonary edema 6

• Pre-existing conditions that may be coincidental:

  • Phrenic nerve injury unrelated to the stroke 4
  • Primary diaphragmatic disorders or myopathies 4

Clinical Implications and Management

• Respiratory dysfunction is an important complication of acute stroke that may increase morbidity and mortality 5
• Careful monitoring of respiratory status is essential in stroke patients 6
• Management approaches include:
  • Supplemental oxygen to maintain saturation >94% 6
  • Positioning patients to optimize respiratory function (head of bed elevated 15-30° in patients at risk for airway obstruction) 6
  • Non-invasive ventilation may be beneficial in cases of respiratory failure 1
  • Early treatment of associated pneumonia with appropriate antibiotics 6

Diagnostic Approach

• Chest X-ray showing elevated hemidiaphragm should prompt further evaluation 1, 5
• Fluoroscopic examination to assess diaphragmatic movement 5
• Phrenic nerve conduction studies may help differentiate central from peripheral causes 2
• Pulse oximetry monitoring to detect hypoxia 6

Early recognition of diaphragmatic dysfunction in stroke patients is important as it may contribute to respiratory complications and affect overall outcomes.