Ross Hauser, MD

At Caring Medical, we see patients with cervical spine instability who describe a wide range of neurologic-like and autonomic symptoms. The neurologic-like symptoms and conditions of Cervical Spine Instability are often mixed, mingled, and concurrent. A person may have neck pain, headaches, dizziness, swallowing difficulties, heart palpitations, gastrointestinal symptoms, throat sensations, or changes in the voice. One of the more puzzling symptoms reported by some of these patients is dysphonia, a change in voice quality, strength, pitch, or the effort required to speak.

Patients will tell stories that voice problems are just one of the many problems they have and that all these problems are seemingly unrelated. In fact, their throat, voice, and swallowing problems appeared one day “out of nowhere” and in some cases were accompanied by a new allergic reaction to foods they have always eaten without a problem. Sudden sensations of dizziness, fainting, skin rashes accompanied this new onset of symptoms.

While these people’s symptoms appeared to be an obvious allergic reaction, that was not the answer. A later diagnosis of mast cell activation syndrome was suspected. Further, in some, a diagnosis of upper cervical instability was suspected when underlying these symptoms were neck pain, inability to hold the head up, headaches, and twitches and tremors began to manifest themselves.

There are many well-established causes of dysphonia.

Persistent hoarseness requires appropriate evaluation for disorders of the vocal folds and larynx, including inflammation, vocal-fold lesions, reflux-related conditions, vocal-fold paralysis or paresis, neurologic disease, trauma, tumors, and other structural abnormalities.

The patients discussed in this article represent a narrower group. These are people whose voice problems may occur as part of a much broader collection of neck, swallowing, neurologic, and autonomic symptoms, particularly when conventional evaluation has not provided a complete explanation.

In these patients, we may look at vagus nerve dysfunction contributing to some of these voice and swallowing symptoms, and could cervical instability be one potential source of stress on this nerve in selected patients?

The vagus nerve, the symptoms, the voice

There are three motor branches of cranial nerve X (vagus nerve) that have bilateral upper motor neuron innervation (nerve signals that go up and down both sides of your neck that make various muscles move) and consist of:

1) the pharyngeal branch, which supplies the muscles of the soft palate and pharynx;

2) the superior laryngeal nerve, which supplies the inferior pharyngeal constrictor (the muscles that also move food down your throat) and cricothyroid muscles of the larynx, which are responsible for pitch adjustments of the voice; and

3) the recurrent laryngeal branches, which innervate all of the other intrinsic muscles of the larynx.

Damage to the recurrent laryngeal nerve can temporarily or permanently lead to hoarseness. In regard to voice, the sensory division of the vagus nerve receives information from the mucous membranes lining the larynx and vocal cords, and the stretch receptors in the muscle spindles of the larynx.

The larynx or voice box is involved in breathing, producing sound, and protecting the trachea against food aspiration (going down the “wrong way.”) The larynx houses the vocal folds and manipulates the pitch and volume of the voice, which is essential for phonation (the ability to make sounds). The larynx is located in the front of the neck at the level of C3-C6.

The muscles of the larynx are innervated by the vagus nerve.

When the vocal cords are abducted, air can enter and go into the lungs and we can breathe. When the vocal cords are adducted sounds are produced and we can speak. As mentioned, the vocal folds (cords) have to be closed also when swallowing so food does not ‘go down the wrong pipe’. The intrinsic laryngeal muscles are responsible for controlling sound production. Cricothyroid muscles lengthen and tense the vocal folds, as occurs with talking. Posterior cricoarytenoid muscles abduct and externally rotate the arytenoid cartilages, resulting in abducted vocal folds. This is the position of breathing.

If both posterior cricoarytenoid muscles are not working from a bilateral recurrent laryngeal nerve injury, the person can have a very difficult time breathing. All muscles of the vocal cords are innervated by the recurrent branch of the vagus nerve except the cricothyroid muscles, which are innervated by the external laryngeal branch of the superior laryngeal nerve, another branch of the vagus nerve.

A patient with a lesion in the laryngeal portion of the vagus nerve most likely will complain of a hoarse voice, difficulty in swallowing (dysphagia), and choking when drinking fluids. There can be a loss of the gag reflex or the uvula deviating away from the side of the lesion because there is a failure of the palate to elevate on that side because of loss of muscle strength of the levator palatini muscle.

The proper functioning of the larynx is critical for life itself. It is involved in swallowing, breathing, eating, coughing, vomiting, and other vital functions. The sensory receptors in the larynx are innervated by the internal branch of the superior laryngeal nerve with cell bodies in the nodose ganglion. The nodose ganglion sits right by the transverse processes of the C1 vertebrae. There are many laryngeal neurologic reflexes that function during crises to keep the larynx open or closed. All of these reflexes are primarily dependent on the vagus nerve. Again the only muscle-producing vocal fold (cord) opening in the larynx is the posterior cricoarytenoid. When it contracts it pulls the arytenoid backward and rocking the vocal process upward and laterally. It is constantly active with greater increases in tone during inspiration for vocal fold opening.

Dysphonia and dysphagia frequently occur together

Voice and swallowing problems are closely related anatomically and neurologically. A large 2025 study (1) using the National Institutes of Health All of Us database examined 266,612 adults and found a striking association between dysphagia and dysphonia. Dysphonia was present in 14% of patients with dysphagia compared with 1.9% of patients without dysphagia. After adjustment for other factors, patients with dysphagia had approximately 6.8 times greater odds of also having dysphonia.

The study does not suggest that cervical instability is responsible for this relationship. Rather, it demonstrates how frequently abnormalities of voice and swallowing coexist. This is important to our patient population because the person we evaluate may not simply say, “My voice is hoarse.” Instead, the patient may describe:

• neck pain; hoarseness; throat sensations; difficulty swallowing; dizziness; autonomic symptoms.

Understanding why these symptoms may occur together requires looking at the neurologic control of the larynx—and particularly the vagus nerve.

The vagus nerve is one of the major nerves controlling the voice

The vagus nerve, cranial nerve X, is one of the most extensive nerves in the human body. It originates in the brainstem, exits the skull through the jugular foramen, travels through the neck within the carotid sheath, and ultimately sends branches throughout the chest and abdomen. It is also intimately involved with the larynx.

Three important vagal motor pathways are relevant to voice and swallowing.

• The pharyngeal branch: The pharyngeal branch contributes to the movement of muscles of the soft palate and pharynx and therefore plays an important role in swallowing.
• The superior laryngeal nerve: The superior laryngeal nerve divides into internal and external branches.
  • The external branch innervates the cricothyroid muscle. This muscle lengthens and tenses the vocal folds and is particularly important for controlling vocal pitch.
  • The internal branch provides important sensation to the larynx above the vocal folds and participates in protective airway reflexes.
• The recurrent laryngeal nerve: The recurrent laryngeal nerve supplies nearly all the remaining intrinsic muscles of the larynx. Damage or dysfunction of this nerve can produce vocal-fold weakness or paralysis, leading to hoarseness, breathiness, vocal fatigue, swallowing difficulty, and ineffective coughing.

The larynx must coordinate speaking, breathing, and swallowing

The larynx, or voice box, sits in the anterior neck, approximately at the C3-C6 levels. Its function extends well beyond speech.

The larynx participates in:

• Voice production.
• Breathing.
• Swallowing.
• Coughing.
• Airway protection.
• Prevention of aspiration.

This helps explain why neurologic dysfunction involving vagal pathways may produce more than hoarseness. A patient may simultaneously experience changes in voice, swallowing, coughing, throat sensation, or airway protection.

New research is examining dysphonia and the autonomic nervous system

One development is research into a possible relationship between voice disorders and autonomic nervous system regulation was a 2024 study where, researchers published a protocol specifically designed to investigate autonomic dysfunction in patients with functional dysphonia. The researchers noted that autonomic dysfunction remains understudied in voice disorders and highlighted an important anatomical connection: the vagus nerve both innervates the larynx and participates in regulation of the autonomic nervous system. (2)

The researchers designed their investigation to compare patients with functional dysphonia with healthy controls using physiological measurements including heart-rate variability, skin conductance, respiration, and cardiac measures. They are also investigating whether heart-rate variability biofeedback aimed at improving autonomic regulation can influence voice function when used alone or with conventional voice therapy.

This research does not establish autonomic dysfunction as the cause of all functional dysphonia, and the publication describes a study protocol rather than completed clinical results. Nevertheless, it reflects an important direction in voice research: dysphonia may sometimes need to be considered within a broader neurophysiological and autonomic context.

Objective voice function has been associated with autonomic activity

Another 2024 study (3) provides additional evidence for this relationship. Researchers measured heart-rate variability during a vocal stress test and compared it with objective measurements of vocal function. They found significant relationships between heart-rate variability and voice function. Greater impairment in objective vocal function was associated with greater sympathetic predominance during vocal stress.

The researchers suggested that voice function may potentially serve as a “warning signal” for processes occurring within the autonomic nervous system. Again, this does not demonstrate that autonomic dysfunction causes a particular patient’s hoarseness. What it does show is that voice production and autonomic physiology may be more closely connected than traditionally appreciated. For patients whose voice problems occur alongside palpitations, dizziness, lightheadedness, gastrointestinal problems, abnormal sweating, or other autonomic symptoms, this research provides additional evidence for this relationship.

Researchers measured heart-rate variability during a vocal stress test and compared it with objective measurements of vocal function. They found significant relationships between heart-rate variability and voice function. Greater impairment in objective vocal function was associated with greater sympathetic predominance during vocal stress. The researchers suggested that voice function may potentially serve as a “warning signal” for processes occurring within the autonomic nervous system. Again, this does not demonstrate that autonomic dysfunction causes a particular patient’s hoarseness.

What it does show is that voice production and autonomic physiology may be more closely connected than traditionally appreciated. For patients whose voice problems occur alongside palpitations, dizziness, lightheadedness, gastrointestinal problems, abnormal sweating, or other autonomic symptoms, this research is may shed some light on their issues.

Vagal neuropathy can cause hoarseness

There is also established clinical evidence that dysfunction involving the vagus nerve and its laryngeal branches can alter the voice. A 2024 case report (4) from Mayo Clinic described a patient who developed progressive hoarseness and vocal-fold paralysis after implantation of a vagus nerve stimulator. Investigation determined that the stimulator coil was mechanically compressing the vagus nerve. The patient underwent removal of the compressive coil and vagal neurolysis.

The case involved an implanted medical device—not cervical instability. Therefore, it should not be interpreted as evidence that cervical instability causes vagus nerve compression. However, it demonstrates an important anatomical principle: Mechanical compression of the cervical vagus nerve can cause vagal neuropathy, vocal-fold dysfunction, and progressive hoarseness.

Voice alteration is also common when the vagus nerve is electrically stimulated

A 2024 systematic review (5) and meta-analysis examining complications of implanted vagus nerve stimulation provides additional evidence of the intimate relationship between vagal activity and the voice. Across the included studies, 1,474 patients received implanted vagus nerve stimulation. Voice alteration or hoarseness was the most commonly reported adverse event, occurring in 671 patients, or approximately 45.5%. Cough, breathing symptoms, and other complaints were also reported.

Again, implanted electrical stimulation is a very different mechanism from cervical instability. But these studies reinforce a fundamental point:

Alteration of vagus nerve function can alter laryngeal function and the voice.

The remaining question for our patient population is whether abnormal cervical mechanics can affect the vagus nerve in another way.

Why look at cervical instability?

After exiting the jugular foramen, the vagus nerve descends through the neck within the carotid sheath alongside the internal carotid/common carotid artery and internal jugular vein. The inferior vagal, or nodose, ganglion is located high in the neck near the upper cervical region. This places important portions of the vagus nerve within a complicated structural environment containing the skull base, upper cervical vertebrae, cervical muscles, ligaments, arteries, veins, and other cranial nerves.

At Caring Medical, this anatomy has led us to investigate whether significant abnormalities of cervical structure and stability could potentially alter the mechanical environment surrounding the vagus nerve.

Cervicovagopathy: a proposed cervical cause of vagus nerve dysfunction

In a 2025 Frontiers in Neurology paper, (6) we published and proposed the term cervicovagopathy to describe vagus nerve dysfunction potentially associated with cervical spine pathology. We suggested that ligamentous cervical instability, abnormal cervical structure, forward head posture, and abnormal vertebral motion may potentially subject the cervical vagus nerve to excessive mechanical stress in susceptible individuals.

References

1 He L, Zhao R, Curtis J, Graham‐Tutt C, Rameau A. Association of dysphonia in patients with dysphagia in the United States: A national database study. The Laryngoscope. 2025 Sep;135(9):3248-56. [Google Scholar]
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