Vocal cords, also called vocal folds, serve many functions in the human body. First, they play an important role in the production of a child’s voice. Secondly, they play an important role during swallowing and are one of the main ways that children are able to protect their airway while eating and drinking. When children swallow, closure of the vocal cords ensures that no food or liquid unnecessarily passes into the airway. Thirdly, they regulate pressure in the lungs and airway during exercise and coughing.
As a result of their many functions, problems with the vocal cords can lead to many different symptoms, including changes in the voice, difficulty with breathing, exercising or eating.
Vocal cord immobility or paralysis can involve one (unilateral) or both (bilateral) vocal cords. When the nerve is injured or not working properly to move the vocal cord, the immobility is called “paralysis”.
Unilateral vocal cord paralysis (UVCP) is more common than bilateral vocal cord paralysis, and the left vocal ford is more frequently involved. Unilateral vocal cord paralysis can occur after a direct injury to the nerve (e.g. after forceps delivery, or after surgery in the neck or chest), or after some infections. The cause may also be unknown. Symptoms include a weak voice or a breathy cry. Because vocal cords serve an important function in keeping food and liquids out of our airway when we swallow, UVCP may lead to coughing and choking with feeding. This is more common with liquids, and can cause repetitive pneumonias. Often the injury to the nerve has potential to heal, and resolution of vocal cord paralysis in children is common.
Treatment depends on the reason for paralysis and the symptoms of the patient. Some children may simply be observed in anticipation of the return of vocal cord function. Others may require short or long-term interventions. Short-term interventions include vocal cord injection, a procedure performed in the operating room under a microscope. Long-term interventions include the placement of permanent laryngeal implants and nerve grafting procedures, and are performed in patients with a low likelihood of spontaneous improvement, usually after 12-24 months of vocal cord paralysis.
Bilateral vocal cord paralysis (BVCP) is less common than UVCP, and is often present at birth. It may be associated with other abnormalities in the nervous system, but most cases do not have an identifiable cause. Symptoms usually arise during infancy, and include feeding difficulty, inspiratory stridor (a high pitch noise when breathing in) and airway obstruction. The voice and cry are often normal.
BVCP is diagnosed using a flexible endoscope through the child’s nose with the child awake. Once a diagnosis is made, children often undergo brain MRI scans to evaluate for a treatable neurologic condition that may lead to the vocal cord paralysis. Other possible studies that may be requested include swallowing studies, sleep studies and heart ultrasound studies.
Because BVCP has the potential to cause airway obstruction, treatment is almost always initiated. Treatment may include a tracheostomy (breathing tube in the neck) during infancy, while waiting for the paralysis to resolve. Occasionally, an endoscopic procedure designed to expand the airway can be performed to avoid tracheostomy. Occasionally, observation without intervention is possible. If vocal cord paralysis remains permanent, several surgical procedures can be performed to widen the airway with the hope of removing the tracheostomy tube. All procedures on the vocal cords in patients with BVCP have the ability to weaken the voice and increase the risk of aspiration (food or liquid accidentally going into the airway). All procedures require a careful assessment and balance between the risks and benefits of the intervention.