Phrenic Nerve

What is the phrenic nerve?

The phrenic nerve controls your diaphragm and is essential to your ability to breathe. The nerve sends signals that make your diaphragm contract (become thicker and flatter). This movement gives your lungs room to expand and take in air (inhalation). After this, the phrenic nerve relaxes your diaphragm, and your lungs return to their starting position, pushing out air (exhalation) and becoming smaller.

What is the function of the phrenic nerve?

Your phrenic nerve is an important part of your respiratory system that helps you breathe. It’s the only nerve that gives your diaphragm movement (motor function). It sends the signals that make your diaphragm expand and contract when you breathe.

Your phrenic nerve also provides touch and pain sensations to your:

• Diaphragm and diaphragmatic pleura (the tissue that covers the upper part of your diaphragm)
• Mediastina pleura (thin tissue that covers the space in your chest cavity between your lungs)
• Pericardium (the protective sac around your heart)
• Peritoneum (the thin, protective lining inside your abdomen)

Where is the phrenic nerve?

Your phrenic nerve starts in your neck and runs down through your chest to reach your diaphragm. It starts near the C3 vertebra in your neck (your cervical spine) and connects to the C4 and C5 vertebrae. It travels past your heart and lungs in your chest before reaching your diaphragm. It’s connected to nerve roots in your spinal cord along its path.

What are the left and right phrenic nerves?

You actually have two phrenic nerves — a left and a right. Each one performs the same job. The left phrenic nerve controls the left side of your diaphragm. The right nerve controls your diaphragm’s right side.

What conditions and disorders affect the phrenic nerve?

Anything that damages your phrenic nerve can weaken or paralyze your diaphragm. If your phrenic nerve can’t control your diaphragm as it should, it won’t be able to change shape to let your lungs move and work correctly. This can make it hard to breathe.

Paralysis can affect one side of your diaphragm (unilateral) or both sides (bilateral). If you experience severe bilateral diaphragm paralysis, you may need a ventilator (mechanical ventilation) to breathe.

What causes a paralyzed diaphragm?

Causes of diaphragm paralysis include:

• Autoimmune diseases (like Guillain-Barré syndrome) and inflammatory conditions (like Parsonage-Turner syndrome)
• Birth defects or trauma during labor and delivery
• Cervical spondylosis
• Complications from neck or chest surgeries or traumas
• Neurological disorders like amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS)
• Spinal cord injuries
• Spine tumors, lung cancer and metastatic cancers

What are the signs of a paralyzed diaphragm?

Symptoms of a paralyzed diaphragm usually include:

• Shortness of breath (especially when you’re lying down)
• Having pneumonia that comes back (recurs) often
• Sleep apnea or other new sleep disorders
• Unusually weak crying in babies

Symptoms of a paralyzed diaphragm can be hard to notice. That’s especially true if you have unilateral diaphragm paralysis. Visit a healthcare provider if it feels like you can’t catch your breath or you notice any new pain or other symptoms.

What role does the phrenic nerve have with hiccups?

Sometimes, an irritated phrenic nerve causes hiccups that last for days or even a month or longer. Surgical procedures, tumors and other issues may irritate your phrenic nerve and cause persistent hiccups.

Persistent hiccups can be uncomfortable and annoying. They can affect your ability to talk, sleep and eat. Treatments for persistent hiccups include:

• Oral medications, including chlorpromazine, baclofen and gabapentin
• Nerve blocks to stop nerve signals that trigger diaphragm contractions
• Surgery (phrenicotomy) to sever your phrenic nerve, permanently paralyzing one side of your diaphragm (it’s rare to need this)

How can I protect my phrenic nerve?

These steps can keep your phrenic nerve (and the rest of your nervous system) healthy:

• Eat plenty of healthy food and maintain a weight that’s healthy for you.
• Get a healthy amount of sleep.
• Get plenty of exercise and physical activity.
• Manage conditions like diabetes and high blood pressure that can damage your nerves.
• Manage stress.
• Try to quit smoking and avoid using other forms of tobacco and nicotine.

When should I talk to a doctor?

Visit a healthcare provider if you notice any new symptoms that affect your breathing, including:

• Hiccups that don’t go away on their own
• Shortness of breath or trouble breathing, especially if you have to prop your head up with multiple pillows or cushions to breathe comfortably lying down
• Signs of sleep apnea, like new snoring, waking up gasping or feeling extreme fatigue
• Unexplained shoulder pain or arm weakness, especially if they happen along with shortness of breath