The vagus nerve is the longest cranial nerve in the body and runs from the brainstem down to the abdomen. It controls several important functions like digestion, heart rate, sweating, and speech. Compression or irritation of the vagus nerve can cause a range of symptoms that can significantly impact daily life.
What is the vagus nerve?
The vagus nerve is the tenth cranial nerve and is a mixed nerve that contains both sensory and motor fibers. It originates in the medulla oblongata of the brainstem and extends downwards, passing through the neck and thorax before terminating in the abdomen.
The vagus nerve controls the parasympathetic nervous system which is responsible for promoting rest-and-digest activities that occur when the body is relaxed. It innervates the muscles of the pharynx and larynx as well as various organs in the chest and abdomen including the heart, lungs, and digestive tract.
What are the functions of the vagus nerve?
The vagus nerve performs a number of critical functions in the body:
- Controls heart rate and contraction of the heart
- Stimulates digestive tract motility and secretion
- Regulates liver function and glucose metabolism
- Stimulates gastric acid secretion
- Increases pancreatic exocrine and endocrine secretions
- Regulates sweating and temperature control
- Plays a role in taste sensations from the tongue
- Supplies motor parasympathetic fibers to most of the laryngeal, pharyngeal, and esophageal muscles
- Provides sensory information from the external auditory canal, middle ear, and pharynx
Any disruption in these functions due to compression or irritation of the vagus nerve can result in troubling symptoms.
What causes compression of the vagus nerve?
There are several potential causes of vagus nerve compression including:
Tight neck muscles
Chronic muscle tension or spasm in the muscles of the neck like the sternocleidomastoid or scalene muscles can compress the vagus nerve as it emerges from the skull. Improper posture that strains the neck can contribute to this issue.
Enlarged blood vessels
An enlarged blood vessel like an aneurysm or atherosclerotic plaque inside the carotid arteries in the neck can press on the vagus nerve.
Cervical spine disorders
Conditions that affect the cervical vertebrae in the neck including bone spurs, herniated discs, stenosis, or injuries can narrow the space available for the vagus nerve and compress it.
Neck tumors
Benign or malignant tumors in the neck including cancers of the thyroid, lymph nodes, salivary glands etc. can grow large enough to compress surrounding structures like the vagus nerve.
Chiari malformation
This condition causes the cerebellar tonsils to descend out of the skull and can affect the exiting cranial nerves like the vagus nerve.
Poor posture
Bad posture that strains the neck like having the head constantly tilted forward can potentially contribute to compression of the vagus nerve.
What are the symptoms of a compressed vagus nerve?
Some common signs and symptoms that may indicate a compressed or irritated vagus nerve include:
Hoarseness
Since the vagus nerve innervates the vocal cords, a compressed nerve can cause recurrent laryngitis resulting in hoarseness and voice changes.
Difficulty swallowing
The vagus nerve controls muscles of the pharynx and larynx that are involved in swallowing. Nerve compression can make it feel like food is sticking in your throat when you swallow.
Choking or coughing when eating
Related to the swallowing difficulties, food may tend to “go down the wrong pipe” causing choking, coughing, or gagging while eating due to vagus nerve disruption.
Heart palpitations
Since the vagus nerve helps control heart rate, damage can lead to a racing heart or skipped beats.
Abdominal pain or nausea
Compressed vagus nerve fibers in the abdomen may cause pain, bloating, nausea, or vomiting after eating.
Syncope
Some patients may experience dizziness or fainting spells related to the vagal nerve’s role in cardiovascular function.
Tinnitus
Ringing, buzzing or roaring sounds in the ears can arise from compression of the vagus nerve fibers that supply the auditory canal and middle ear.
Unexplained anxiety
The vagus nerve is involved in mood regulation so disruption may present as new onset anxiety or increased day-to-day worries.
How is vagus nerve compression diagnosed?
If symptoms indicate potential vagus nerve compression, the following diagnostic approaches may be undertaken:
Imaging studies
MRI or CT scans can visualise the vagus nerve pathway and detect any mass lesions, tumors, aneurysms, muscle hypertrophy, or bone spurs pressing on the nerve.
Blood tests
Blood tests help rule out potential causes like thyroid disorders that could lead to enlarged neck vessels impinging on the vagus nerve.
Neurologic examination
A neurologic exam assesses cranial nerve function and can help confirm which branch of the vagus nerve is impacted based on your symptoms.
Laryngoscopy
A camera inserted through the mouth allows visual inspection of the larynx and vocal cords to check for abnormalities pointing to vagus nerve damage.
Swallow test
You will be asked to swallow liquids and solids of varying textures, with the doctor observing carefully for signs of choking, coughing, or aspiration during the process.
Cardiac testing
Your doctor may order electrocardiograms (ECG) to look for heart rhythm disturbances and an echocardiogram to visualise cardiac structure and function if your symptoms relate to the vagus nerve’s parasympathetic cardiac fibers.
How is vagus nerve compression treated?
Treatment depends on the underlying cause but may involve:
Medication
Corticosteroids help reduce inflammation pressing on the nerve. Muscle relaxants alleviate spasms and antacids reduce excess stomach acid secretion.
Surgery
Removal of compressive lesions like tumors, aneurysms or bone spurs. Selective sectioning of the nerve fibers may help certain symptoms.
Physical therapy
Stretching exercises and posture correction helps lengthen tight cervical muscles. Heat, massage, and spinal mobilization exercises may provide relief.
Vagus nerve stimulation
Electrical impulses to the vagus nerve helps modulate some of its parasympathetic functions.
When to see a doctor
Consult your physician promptly if you experience any persistent symptoms like:
- Choking or coughing when eating
- Hoarseness lasting over 2 weeks
- Shortness of breath
- Difficulty swallowing
- Heart palpitations
- Severe unexplained nausea
- Fainting
Timely evaluation is important, as some causes like tumors or aneurysms can be serious if left untreated.
Conclusion
The vagus nerve performs diverse critical functions so compression of this long wandering nerve can result in varied symptoms like swallowing changes, stomach upset, heart abnormalities, and more based on which nerve branch is affected. Imaging studies along with a thorough history and directed physical examination help identify the location and cause of nerve compression. Prompt treatment can help alleviate symptoms and prevent permanent injury to the vagus nerve.