出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/08/21 18:05:17」(JST)
| Vocal cord dysfunction | |
|---|---|
| Classification and external resources | |
| ICD-9 | 478.3-478.5 |
Vocal cord dysfunction (VCD) is a condition that affects the vocal folds, commonly referred to as the vocal cords, which is characterized by full or partial vocal fold closure that usually occurs during inhalation for short periods of time; however, it can occur during both inhalation and exhalation.[1] This closure may cause airflow obstruction; however, it rarely results in reduction of oxygen saturation.
Symptoms can include shortness of breath dyspnea, wheezing, coughing, tightness in the throat, skin discoloration due to oxygen deprivation, noise during inhalation stridor, and in severe cases, loss of consciousness.[2] The differential diagnosis for Vocal Cord Dysfunction, also referred to as paradoxical vocal fold motion (PVFM) and paradoxical vocal cord movement (PVCM), includes vocal fold swelling from allergy, asthma, or some sort of obstruction of the vocal folds or throat area that may cause breathing difficulty. Anyone suspecting this condition should be evaluated by a physician and the vocal folds (voice box) should be looked at to rule out any sort of obstruction that may create difficulty breathing.
For individuals who experience a persistent difficulty with inhaling, a neurological evaluation is warranted to discover if there is a neurologic cause for the breathing difficulty. Neurologic causes for persistent difficulty inhaling can include brain stem compression, cerebral palsy, etc.[3]
VCD "episodes" can be triggered suddenly, or come on gradually. Many different things can trigger an episode. The primary causes for a VCD episode are believed to be gastroesophageal reflux disease (GERD), extra-esophageal reflux (EERD), exposure to inhaled allergens, post nasal drip, exercise, or neurological conditions that can cause difficulty inhaling only during waking.[1] Other published scientific articles emphasize anxiety or stress as the primary cause; however, more recent literature indicates a likely physical etiology for this disorder. This disorder has been observed throughout the lifespan, from infants through old age, with the observation of its occurrence in infants leading clinicians to believe that a physiological cause is likely, such as reflux or allergy. Also certain medications, such as antihistamines for allergies, can provide a drying effect to the mucus membranes, which can further cause the vocal cords to be irritated or hypersensitive.
This syndrome can mimic asthma, anaphylaxis, collapsed lungs, pulmonary embolism, or fat embolism, and can lead to an inaccurate diagnosis and inappropriate treatment which may be harmful to the patient.[4] Many VCD patients are diagnosed with asthma, but are unresponsive to asthma therapy, including bronchodilators and steroids. Among adult patients, women tend to be diagnosed more often. Among children and teenage patients, VCD has been linked with high participation in competitive sports and family orientation towards high achievement.
Vocal cord dysfunction co-occurs with asthma approximately 40% of the time.[1] This frequently results in a misdiagnosis of only asthma. Even young children can tell the difference between an asthma attack (primarily difficulty exhaling) and a VCD attack (primarily difficulty inhaling). Knowing the difference between the two will help those who have both know when to use the rescue inhaler prescribed or when to use the breathing recovery exercises trained by an experienced speech language pathologist.
Vocal cord dysfunction is often diagnosed after all other potential conditions are ruled out. Patients must be unresponsive to medication and other potential treatments before VCD will be considered. This often means that the patient has been hospitalized on several occasions due to episodes that are unresponsive to "normal" treatments, such as asthma medication.
The most effective way of diagnosing VCD is to perform a nasolaryngoscopy during an episode. A clinician can then view the movement of the vocal folds and determine whether there is any abnormality. If the endoscopy is not performed during an episode, it is likely that the vocal folds are moving normally and the clinician will not detect an abnormality. However, in severe cases, VCD is detectable outside of episode by observing persistent swelling of the vocal folds and indications of irritation.[5] The spirometry may also be useful to establish the diagnosis of VCD when performed during a crisis or after a nasal provocation test.[6]
The first step to treat VCD is to stop any unnecessary treatment. The use of steroids is not effective in VCD unless needed to treat underlying asthma. The drugs should be discontinued to avoid the morbidity associated with their use and to prevent severe long-term consequences, including growth retardation in children. Speech therapy (which involves teaching the patient to breathe more efficiently) is the first line of treatment for VCD and by itself is sometimes sufficient to correct the disorder.[7]
Acute treatments can include heliox, intermittent positive pressure ventilation and continuous positive airway pressure. Severe cases may require a tracheotomy for temporary relief. Botox injections can also be made into the vocal folds.
If there is an underlying condition to which vocal cord dysfunction is secondary, it is important to treat the primary condition. This alone can help control VCD.[8]
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| リンク元 | 「VCD」 |
| 関連記事 | 「dysfunction」「cord」「cor」「vocal」 |