A mix and variance of these symptoms are found in mixed spasmodic dysphonia.Symptoms of spasmodic dysphonia typically appear in middle aged people, but have also been seen in people in their twenties, with symptoms emerging as young as teenage years. Cause
Although the exact cause of spasmodic dysphonia 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 parturitionIt has not been established whether these factors directly affect 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.
Voice therapy
Voice therapy appears to be ineffective in cases of true spasmodic dysphonia. However, as it is difficult to distinguish between spasmodic dysphonia and functional dysphonias, and misdiagnosis is relatively common, trial of voice therapy is often recommended before more invasive procedures are tried. Some also state that it is useful for mild symptoms and as an add-on to botox therapy and others report success in more severe cases. Laryngeal manual therapy, which is massaging of the neck and cervical structures, also shows positive results for intervention of functional dysphonia. Surgery
If other measures are not effective, surgery may be considered; however, evidence to support surgery as a treatment for SD is limited. Treatment outcomes are generally positive, though more research is required to determine its effectiveness. Post-surgery voices can be imperfect and about 15% of people have significant difficulties. If symptoms do recur, this typically happens in the first 12 months. As of 2011, surgery was rarely used as a treatment approach for SD. Surgical approaches include recurrent laryngeal nerve resection, selective laryngeal adductor denervation-reinnervation (SLAD-R), thyroplasty, thyroarytenoid myectomy, and laryngeal nerve crush. Recurrent laryngeal nerve resection involves removing a section of the recurrent laryngeal nerve. Recurrent laryngeal nerve avulsion is a more drastic removal of sections of the nerve, and has positive outcomes of 80% at three years. SLAD-R is effective specifically for adductor spasmodic dysphonia, for which it has shown good outcomes in about 80% of people at 8 years. Thyroplasty changes the position or length of the vocal folds.