Normal functioning vocal folds Although the exact cause of<unk>  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 affect the development of<unk>  <unk> , 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<unk> . 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<unk>  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<unk>  and specific genes.<unk>  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.<unk>  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. This was especially true in the 19th and 20th centuries. No medical organizations or groups take this position. A comparison of<unk>  patients compared with vocal fold paralysis (VFP) patients found that 41.7% of the<unk>  patients met the DSM-IV criteria for psychiatric comorbidity compared with 19.5% of the VFP group. However, another study found the opposite, with<unk>  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<unk> , to 29.4 percent (5/17) for functional<unk> , 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 investigations 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<unk> . The opinion that<unk>  is psychogenic is not upheld by experts in the scientific community.<unk>  is formally classified as a movement disorder; it is a type of focal dystonia known as laryngeal dystonia.
Spasmodic dysphonia
Stuttering
Muscle tension dysphonia
Dysphagia lusoria
Odynophagia
Anotia
Pseudodysphagia
Hallucinatory palinopsia