The following increase an individual's chances for acquiring VCD:

- Upper airway inflammation (allergic or non-allergic rhinitis, chronic sinusitis, recurrent upper respiratory infections)

- Gastroesophageal reflux disease

- Past traumatic event that involved breathing (e.g. near-drowning, suffocation)

- Severe emotional trauma or distress

- Female gender

- Playing a wind instrument

- Playing a competitive or elite sport

The exact cause of VCD is not known, and it is unlikely that a single underlying cause exists. Several contributing factors have been identified, which vary widely among VCD patients with different medical histories. Physical exercise (including, but not limited to, competitive athletics) is one of the major triggers for VCD episodes, leading to its frequent misdiagnosis as exercise-induced asthma. Other triggers include airborne pollutants and irritants such as smoke, dust, gases, soldering fumes, cleaning chemicals such as ammonia, perfumes, and other odours. Gastroesophageal reflux disease (GERD) and rhinosinusitis (inflammation of the paranasal sinuses and nasal cavity) may also play a role in inflaming the airway and leading to symptoms of VCD as discussed below.

Laryngeal hyperresponsiveness is considered the most likely physiologic cause of VCD, brought on by a range of different triggers that cause inflammation and/or irritation of the larynx (voice box). The glottic closure reflex (or laryngeal adductor reflex) serves to protect the airway, and it is possible that this reflex becomes hyperactive in some individuals, resulting in the paradoxical vocal fold closure seen in VCD. Two major causes of laryngeal inflammation and hyperresponsiveness are gastroesophageal reflux disease (GERD) and postnasal drip (associated with rhinosinusitis, allergic or nonallergic rhinitis, or a viral upper respiratory tract infection (URI)). Rhinosinusitis is very common among patients with VCD and for many patients, VCD symptoms are ameliorated when the rhinosinusitis is treated. GERD is also common among VCD patients, but only some experience an improvement in VCD symptoms when GERD is treated. Other causes of laryngeal hyperresponsiveness include inhalation of toxins and irritants, cold and dry air, episodic croup and laryngopharyngeal reflux (LPR).

VCD has long been strongly associated with a variety of psychological or psychogenic factors, including conversion disorder, major depression, obsessive-compulsive disorder, anxiety (especially in adolescents), stress (particularly stress relating to competitive sports), physical and sexual abuse, post-traumatic stress disorder, panic attacks, factitious disorder and adjustment disorder. It is important to note that anxiety and depression may occur in certain patients as a "result" of having VCD, rather than being the cause of it. Psychological factors are important precipitating factors for many patients with VCD; although exercise is also a major trigger for episodes of VCD, some patients experience VCD co-occurring with anxiety regardless of whether or not they are physically active at the time of the VCD/anxiety episode. Experiencing or witnessing a traumatic event related to breathing (such as a near-drowning or life-threatening asthma attack, for example), has also been identified as a risk factor for VCD.

VCD has also been associated with certain neurologic diseases including Arnold-Chiari malformation, cerebral aqueduct stenosis, cortical or upper motor neuron injury (such as that resulting from stroke), amyotrophic lateral sclerosis (ALS), parkinsonism syndromes and other movement disorders. However, this association occurs only rarely.

Up to now, prevalence studies investigating rates of dysphonia on a large-scale level have been limited. According to a large sample of 55 million patients seeking health-care treatment in the United States, dysphonia can be found in approximately 1% of the population. Higher rates are reported in females and elderly adults, however, dysphonia can be found in both sexes and across age groups. It is proposed that higher rates in females are due to anatomical differences of the vocal mechanism.

Certain occupational groups may be more prone to developing voice disorders, namely dysphonia. Occupations that require extensive use of voice may be at a greater risk such as teachers and singers. However, the evidence is highly variable and must be interpreted carefully.

Smoking is the number one cause of Reinke's edema. Other factors include gastroesophageal reflux, hypothyroidism and chronic overuse of the voice. Smoking is the only risk factor that may lead to cancer. Additionally, the combination of several risk factors increase the likelihood of an individual developing Reinke's edema. For example, an individual who smokes and also has gastric reflux would have an increased susceptibility for developing Reinke's edema over time.

Reinke's edema is commonly diagnosed in middle-aged females with a history of smoking (aged 50 years or older). Because males have lower pitched voices than females, males are less likely to observe a significant changes in the voice, and are therefore less likely to seek treatment. Females also report more physical discomfort due to Reinke's edema. The risk of Reinke's edema increases with age and also with prolonged exposure to smoking. Additionally, individuals in professions that require constant use of the voice, such as singers, teachers, and radio hosts, may be at an increased risk for developing the disease.

Because the disease is heavily linked to smoking, there is no established way to screen for Reinke's edema. Similarly, the only way to prevent Reinke's edema is to avoid smoking. By adopting a non-smoking lifestyle after being diagnosed with Reinke's edema, it is possible to stop the disease's progression, although it is not possible to reverse it. Therefore, it is critical to maintain a non-smoking lifestyle even after surgery, because the fluid can re-emerge. In fact, in many cases surgeons will not perform surgery without the guarantee that the individual will stop smoking.

Various stimuli including asthma, allergies, exercise, stress, and irritants such as smoke, dust, fumes, liquids, and food can trigger laryngospasm. It is common in drowning, both as a direct response to inhalation of water, and as a complication during rescue and resuscitation due to aspiration of vomit.

In some individuals laryngospasm can occur spontaneously or as a result of reflux or impaired swallowing. GERD is a common cause of spontaneous laryngospasm. Treating GERD can lessen the frequency of spasms. The onset of spasms may be caused by a viral infection.

It is also a complication associated with anesthesia. The spasm can happen often without any provocation, but tends to occur after tracheal extubation. In children, the condition can be particularly deadly, leading to cardiac arrest within 30–45 seconds, and is a possible cause of death associated with the induction of general anesthesia in the pediatric population. It can sometimes occur during sleep, waking up the sufferer. This usually occurs when the person has gastric acidity and develops re-flux during sleep, where the gastric acid causes irritation which will cause the spasm attack.

It is also a symptom of Hypoparathyroidism

PND is suggested to be a cause of extra-oral halitosis, especially when a sinus infection is also present. Acid reflux or heartburn is believed to aggravate and in some cases cause post-nasal drip. Post-nasal drip can be a cause of laryngeal inflammation and hyperresponsiveness, leading to symptoms of vocal cord dysfunction (VCD).

First-generation antihistamine has been suggested as first-line therapy to treat post-nasal drip.

When laryngospasm is coincident with a cold or flu, it may be helpful for some sufferers to take acid reflux medication to limit the irritants in the area. If a cough is present, then treat a wet cough; but limit coughing whenever possible, as it is only likely to trigger a spasm. Drink water or tea to keep the area from drying up. Saline drops also help to keep the area moist. Pseudoephederine may also help to clear any mucus that may cause coughing and thereby triggering more spasms.

Medication challenge tests, such as the methacholine challenge test, have a lower sensitivity for detection of exercise-induced bronchoconstriction in athletes and are also not a recommended first-line approach in the evaluation of exercise-induced asthma.

Mannitol inhalation has been recently approved for use in the United States.

It should be noted, however, that a relatively recent review of the literature has concluded that there is currently insufficient available evidence to conclude that either mannitol inhalation or eucapnic voluntary hyperventilation are suitable alternatives to exercise challenge testing to detect exercise-induced bronchoconstriction and that additional research is required.

Across all posited aetiologies, contact granulomas are more commonly observed in male patients than in female patients, and more commonly in adult patients than in pediatric patients. In cases where gastroesophageal reflux disease is identified as the most likely cause of the granuloma, the patient is most commonly an adult man in his 30s or 40s. When contact granulomas do occur in female and pediatric patients, they usually occur post-intubation. There are no observable age or gender trends within the category of post-intubation patients suffering from contact granulomas, nor within the causation category of vocal abuse history.

For patients in need of tracheal intubation to receive oral drugs, an oversized tube, excessive movement of the tube, or infection can lead to contact granulomas, but this is rare.

The International Olympic Committee recommends the eucapnic voluntary hyperventilation (EVH) challenge as the test to document exercise-induced asthma in Olympic athletes. In the EVH challenge, the patient voluntarily, without exercising, rapidly breathes dry air enriched with 5% for six minutes. The presence of the enriched compensates for the losses in the expired air, not matched by metabolic production, that occurs during hyperventilation, and so maintains levels at normal.

Although the exact cause of spasmodic dysphonia (i.e., laryngeal dystonia) is still unknown, epidemiological, genetic and neurological pathogenic factors have been proposed in recent research.

Risk factors include:

- Being female

- Being middle aged

- Having a family history of neurological diseases (e.g., tremor, dystonia, meningitis and other neurological diseases)

- Stressful events

- Upper respiratory tract infections

- Sinus and throat illnesses

- Heavy voice use

- Cervical dystonia

- Childhood measles or mumps

- Pregnancy and parturition

It has not been established whether these factors directly impact the development of spasmodic dysphonia (SD), however these factors could be used to identify possible and/or at-risk patients.

Researchers have also explored the possibility of a genetic component to SD. Three genes have been identified that may be related to the development of focal or segmental dystonia: TUBB4A, THAP1 and TOR1A genes. However, a recent study that examined the mutation of these three genes in 86 SD patients found that only 2.3% of the patients had novel/rare variants in THAP1 but none in TUBB4A and TOR1A. Evidence of a genetic contribution for dystonia involving the larynx is still weak and more research is needed in order to establish a causal relationship between SD and specific genes.

SD is a neurological disorder rather than a disorder of the larynx, and as in other forms of dystonia, interventions at the end organ (i.e., larynx) have not offered a definitive cure, only symptomatic relief. The pathophysiology underlying dystonia is becoming better understood as a result of discoveries about genetically based forms of the disorder, and this approach is the most promising avenue to a long-term solution.

SD is classified as a neurological disorder. However, because the voice can sound normal or near normal at times, some practitioners believe it to be psychogenic, that is, originating in the affected person's mind rather than from a physical cause. No medical organizations or groups take this position. A comparison of SD patients compared with vocal fold paralysis (VFP) patients found that 41.7% of the SD patients met the DSM-IV criteria for psychiatric comorbidity compared with 19.5% of the VFP group. However, another study found the opposite, with SD patients having significantly less psychiatric comorbidity compared to VFP patients: "The prevalence of major psychiatric cases varied considerably among the groups, from a low of seven percent (1/14) for spasmodic dysphonia, to 29.4 percent (5/17) for functional dysphonia, to a high of 63.6 percent (7/11) for vocal cord paralysis." A review in the journal Swiss Medicine Weekly states that "Psychogenic causes, a 'psychological disequilibrium', and an increased tension of the laryngeal muscles are presumed to be one end of the spectrum of possible factors leading to the development of the disorder". Alternatively, many investigators into the condition feel that the psychiatric comorbidity associated with voice disorders is a result of the social isolation and anxiety that patients with these conditions feel as a consequence of their difficulty with speech, as opposed to the cause of their dysphonia. The opinion that SD is psychogenic is not upheld by experts in the scientific community.

SD is formally classified as a movement disorder, one of the focal dystonias, and is also known as laryngeal dystonia.

Given that certain occupations are more at risk for developing dysphonia (e.g. teachers) research into prevention studies have been conducted. Research into the effectiveness of prevention strategies for dysphonia have yet to produce definitive results, however, research is still ongoing. Primarily, there are two types of vocal training recognized by professionals to help with prevention: direct and indirect. Direct prevention describes efforts to reduce conditions that may serve to increase vocal strain (such as patient education, relaxation strategies, etc.), while indirect prevention strategies refer to changes in the underlying physiological mechanism for voice production (e.g. adjustments to the manner in which vocal fold adduction occurs, respiratory training, shifting postural habits, etc.).

Recent studies have examined the role of specific cell types in Reinke's edema, including the role of vocal cord fibroblasts. In normal tissue, these spindle-shaped CD34+ fibroblasts produce extracellular matrix proteins such as collagen and elastin. Recent findings have shown a morphological change in fibroblasts extracted from the tissue of Reinke's edema to a more dendritic-like shape with several protrusions. Large populations of these altered CD34+ fibroblasts have been found surrounding the areas of edema. They lack normal expression of several Cluster Differentiation (CD) proteins and express additional proteins that are not expressed in normal vocal cord fibroblasts. Furthermore, cigarette smoke was discovered to increase COX-2 and PGE2 expression in fibroblasts, which could indicate the role of cigarette smoke in Reinke's edema.

While smoking is a clear risk factor to Reinke's edema, other risk factors are being identified to explain Reinke's edema in nonsmokers. Research has suggested the role of bacterial colonies in non-neoplastic lesions such as Reinke's edema. Using pyrosequencing, strains of "S. pseudopneumoniae" were found as the dominant bacterial strain across most non-neoplastic lesions. Of all the sequences analyzed, streptococcus represented 72.9% of bacteria found within these lesions. While smoking, gastric reflux, and vocal abuse have been more widely agreed upon in literature as risk factors for Reinke's edema, the altered bacterial cultures could be developed as a diagnostic tool in the future.

The majority of the research within the last ten years focuses on improving surgery for Reinke's edema. Due to the importance of the Reinke's space in speech, it is important that minimally invasive techniques be perfected that minimize the risk of complications. The CO2 laser has been successfully incorporated into the surgical technique, however, there are several other lasers being investigated for use in Reinke's edema. These include photoangiolytic lasers and potassium titanyl phosphate lasers.

Spasmodic dysphonia, also known as laryngeal dystonia, is a disorder in which the muscles that generate a person's voice go into periods of spasm. This results in breaks or interruptions in the voice, often every few sentences, which can make a person difficult to understand. The person's voice may also sound strained or they may be nearly unable to speak. Often onset is gradual and the condition is life long.

The cause is unknown. Risk factors may include family history. Triggers may include an upper respiratory infection, injury to the larynx, overuse of the voice, and psychological stress. The underlying mechanism is believed to typically involve the central nervous system, specifically the basal ganglia. Diagnosis is typically made following examination by a team of healthcare providers.

While there is no cure, treatment may improve symptoms. Most commonly this involves injecting botulinum toxin into the affected muscles of the larynx. This generally results in improvement for a few months. Other measures include voice therapy, counselling, and amplification devices. Rarely surgery may be considered.

The disorder affects an estimated 2 per 100,000 people. Women are more commonly affected. Onset is typically between the ages of 30 and 50. Severity is variable between people. In some work and social life are affected. Life expectancy is, however, normal.

The presbylarynx is a condition in which age-related atrophy of the soft tissues of the larynx results in weak voice and restricted vocal range and stamina. In other words, it is the loss of vocal fold tone and elasticity due to aging which affects voice quality.

Shortness of breath is the primary reason 3.5% of people present to the emergency department in the United States. Of these individuals, approximately 51% are admitted to the hospital and 13% are dead within a year. Some studies have suggested that up to 27% of people suffer from dyspnea, while in dying patients 75% will experience it. Acute shortness of breath is the most common reason people requiring palliative care visit an emergency department.

Voice disorders are medical conditions involving abnormal pitch, loudness or quality of the sound produced by the larynx and thereby affecting speech production. These include:

- Puberphonia

- Chorditis

- Vocal fold nodules

- Vocal fold cysts

- Vocal cord paresis

- Reinke's edema

- Spasmodic dysphonia

- Foreign accent syndrome

- Bogart–Bacall syndrome

- Laryngeal papillomatosis

- Laryngitis

Fremitus appears when teeth move. This can be assessed by feeling and looking at teeth when the mouth is opened and closed.

Airway obstruction may cause obstructive pneumonitis or post-obstructive pneumonitis.

Bogart–Bacall syndrome (BBS) is a voice disorder that is caused by abuse or overuse of the vocal cords.

People who speak or sing outside their normal vocal range can develop BBS; symptoms are chiefly an unnaturally deep or rough voice, or dysphonia, and vocal fatigue. The people most commonly afflicted are those who speak in a low-pitched voice, particularly if they have poor breath and vocal control. The syndrome can affect both men and women.

In 1988 an article was published, describing a discrete type of vocal dysfunction which results in men sounding like Humphrey Bogart and women sounding like Lauren Bacall. BBS is now the medical term for an ongoing hoarseness that often afflicts actors, singers or TV/radio voice workers who routinely speak in a very low pitch.

Treatment usually involves voice therapy by a speech language pathologist.

The list of treatments mentioned in various sources for presbylarynx includes the following list. Always seek professional medical advice about any treatment or change in treatment plans.

- Voice therapy

Hepatic fremitus is a vibration felt over the person's liver. It is thought to be caused by a severely inflamed and necrotic liver rubbing up against the peritoneum. The name 'Monash sign' has been suggested for this clinical sign, after the Monash Medical Centre in Melbourne, Australia.

Lower airway obstruction is mainly caused by increased resistance in the bronchioles (usually from a decreased radius of the bronchioles) that reduces the amount of air inhaled in each breath and the oxygen that reaches the pulmonary arteries. It is different from airway restriction (which prevents air from diffusing into the pulmonary arteries because of some kind of blockage in the lungs). Diseases that cause lower airway obstruction are termed obstructive lung diseases.

Lower airway obstruction can be measured using spirometry. A decreased FEV1/FVC ratio (versus the normal of about 80%) is indicative of an airway obstruction, as the normal amount of air can no longer be exhaled in the first second of expiration. An airway restriction would not produce a reduced FEV1/FVC ratio, but would reduce the vital capacity. The ventilation is therefore affected leading to a ventilation perfusion mismatch and hypoxia.