Causes And Risk Factors Associated With Vocal Cord Paralysis

Vocal cord paralysis, also referred to as vocal fold paralysis, develops when there is a disruption in the nerve signals that normally travel to the larynx (voice box). This disruption causes the muscles within the vocal cords to stop functioning and be paralyzed. Typically, vocal cord paralysis only affects one of the vocal cords; paralysis of both vocal cords is very rare, and it is considered life-threatening. Symptoms of vocal cord paralysis include noisy breathing, loss of vocal pitch or gag reflex, and unproductive coughing. Patients may notice they need to take more breaths than usual while speaking, and they might struggle to speak loudly. Choking or coughing while eating and drinking could occur as well. To diagnose this condition, a specialist will perform a laryngoscopy, and some patients may also need to have a laryngeal electromyography test. These tests can help pinpoint the cause of the paralysis and enable doctors to plan an effective course of treatment.

Some of the most common causes and risk factors for vocal cord paralysis are discussed below.

Chest Or Neck Injury

A chest or neck injury could lead to the paralysis of one or both vocal cords. These injuries could happen during trauma, including car accidents or falls from heights, and they may also occur as an unintended complication of neck or chest surgery. One of the two major nerves that provide input signals to the vocal cords is called the recurrent laryngeal nerve. It controls the muscles that open and close the vocal cords. This nerve is relatively long, and it extends into the chest cavity before detouring back around into the larynx. This detour makes it especially vulnerable to injury during surgery. Some types of neck and chest trauma that could unintentionally injure the recurrent laryngeal nerve include surgery to the heart, lungs, esophagus, carotid artery, thyroid, and cervical spine. In rare cases, the insertion of a breathing tube during surgery for neck and chest injuries could result in vocal cord paralysis.

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Multiple Sclerosis

Multiple sclerosis is a neurological condition that may lead to the paralysis of a single vocal cord, and it also increases the risk of weakness in the vocal cords. The condition develops when the patient's immune system attacks myelin, a protective covering for the body's nerves. This results in communication difficulties between the brain and body, and it eventually leads to nerve damage and deterioration of the nerves themselves. Symptoms of multiple sclerosis include fatigue, tremors, dizziness, double vision, and pain or tingling in various parts of the body. In terms of the vocal cords, multiple sclerosis patients may experience slurred speech, and they may also have a hoarse voice and trouble with swallowing and speaking. To prevent progression of certain types of multiple sclerosis, doctors may prescribe ocrelizumab, beta interferons, dimethyl fumarate, or glatiramer acetate. Voice therapy may be particularly helpful for patients experiencing vocal cord paralysis or weakness.

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Presence Of A Tumor

The presence of a tumor may cause paralysis of one vocal cord. Normally, tumors that lead to vocal cord paralysis are located in or around the cartilage, nerves, and muscles of the larynx, though occasionally, tumors of the neck, chest, and brain may also result in this condition. Both benign (noncancerous) and malignant (cancerous) tumors may impact the vocal cords. The symptoms associated with tumors in or near the larynx include a hoarse voice and many of the same signs associated with vocal cord paralysis itself. For this reason, patients who notice any unusual changes to their voice that persist for more than two weeks should visit a throat specialist promptly. To differentiate between vocal cord paralysis and a tumor, patients may need to have specialized CT or MRI scans, and they could also need to have an endoscopy. If a tumor is discovered, treatment will depend on its size and location. Surgery, radiation, and chemotherapy may all be needed, and patients will be referred to an oncologist.

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Certain Infections

Certain infections may produce temporary or permanent paralysis of one of the vocal cords. For example, research has shown the Epstein-Barr virus, herpes, and Lyme disease lead to inflammation that can cause direct damage to the nerves serving the larynx. Viral or bacterial infections that inflame or injure the vagus nerve, which branches off into the larynx, may also result in vocal cord paralysis. Some research suggests the common cold could also trigger this condition. To diagnose infections that impact the vocal cords, doctors will perform a physical examination, and patients may also need to have blood tests, x-rays, or other advanced imaging studies. Depending on the cause of the infection, antibiotics, antifungal medicine, or intravenous infusions may be beneficial in clearing the infection from the body.

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Throat Surgery

Vocal cord paralysis is one of the potential complications associated with throat surgery. For example, surgery to remove the thyroid gland and certain operations on the spine could both lead to possible paralysis of one of the vocal cords. Rarely, the removal of the thyroid gland may paralyze both of the vocal cords. Spinal surgery carried out through an incision in the front of the neck also carries a risk of paralysis of both vocal cords, and tracheal intubation (the placement of a breathing tube into the patient's windpipe) may also result in damage or paralysis to both of a patient's vocal cords. Patients undergoing throat surgery or an operation on the thyroid, chest, or neck should ask their surgeons about their individual risk of vocal cord damage or paralysis. The surgeons will do everything they can to minimize this risk, and patients will have an opportunity to ask questions about vocal cord damage and other potential complications prior to the surgery. To reduce the risk of potential complications, it is important any surgery on the throat or neck be carried out by a surgeon experienced in these types of procedures.