From the Guidelines
Injury to the phrenic nerve typically occurs through trauma, surgical complications, or disease processes, with the most significant risk being during thoracic or neck surgeries, particularly cardiac procedures, lung cancer operations, or neck dissections, as well as from medical conditions like viral infections and malignancies, and iatrogenic causes such as interscalene nerve blocks and radiation therapy, as supported by recent studies 1.
Causes of Phrenic Nerve Injury
The phrenic nerve can be damaged during various medical procedures and conditions, including:
- Trauma such as motor vehicle accidents, penetrating injuries to the neck or chest, or birth injuries
- Surgical complications, particularly during thoracic or neck surgeries
- Medical conditions, including viral infections (especially herpes zoster), inflammatory disorders like Guillain-Barré syndrome, and malignancies that compress or infiltrate the nerve
- Iatrogenic causes, such as interscalene nerve blocks for shoulder surgery, central venous catheter placement, and radiation therapy to the chest or neck
Vulnerability of the Phrenic Nerve
The phrenic nerve is vulnerable due to its long anatomical course from the cervical spine (C3-C5) through the thorax to innervate the diaphragm, making it susceptible to injury from various sources, as noted in studies on the effects of COVID-19 on respiratory muscle performance 1.
Symptoms and Treatment
When injured, patients may experience breathing difficulties, particularly when lying flat, as the diaphragm is the primary muscle of respiration. Treatment depends on the cause and severity of injury, ranging from observation for spontaneous recovery to surgical interventions like nerve grafting or diaphragmatic pacing in severe cases, with recent guidelines emphasizing the importance of careful surgical technique and medical practice recommendations to reduce the risk of malpractice lawsuits and judgments against surgeons 1.
From the Research
Causes of Phrenic Nerve Injury
- Cervical trauma 2
- Iatrogenic injury in the neck or chest 2, 3
- Neuralgic amyotrophy 2
- Cardiac surgery, particularly with the use of ice slush for myocardial preservation 4, 5 and cardiopulmonary bypass with hypothermia 5
- Other potential risk factors, such as age, ejection fraction, operative/bypass/aortic cross-clamp time, left internal mammary artery use, and diabetes mellitus, have been investigated but not found to be significantly associated with phrenic nerve dysfunction 4, 6
Mechanisms of Phrenic Nerve Injury
- Direct damage to the phrenic nerve during surgery 3, 5
- Cold injury from ice slush used for myocardial preservation 4, 5
- Hypothermia during cardiopulmonary bypass 5