What is spasmodic dysphonia?
Spasmodic dysphonia (also called laryngeal dystonia) is a chronic, neurological voice disorder, motor speech disorder, and dystonia. Let’s break down what all of these fancy terms mean:
- Chronic: It is incurable and life long
- Neurological: It is caused by a neurological impairment (the exact underpinnings of this are still being studied). In a very basic explanation, typically a signal originates from your brain to tell your vocal folds to vibrate. Your body also has sensation feedback mechanisms that send signals back to the brain to regulate movement. It is hypothesized that this sensory-motor feedback loop is disrupted in those with SD. There have been both structural and functional brain dysfunction recognized in those with SD, based on MRI and fMRI studies (I will break down these specific pathophysiology and neurology origin details in another post coming soon!)
- Voice disorder: A condition when the vocal folds (aka vocal cords) do not function properly. Voice disorders can have a “functional” origin meaning that it is caused by misuse of the voice (screaming, shouting, using voice excessively), structural origin (i.e. trauma to the larynx, aging, or cancer), or neurological (i.e. spasmodic dysphonia and vocal tremor). With spasmodic dysphonia there is nothing physically wrong with the vocal mechanism (vocal folds or larynx). The problem lies in the neurological networks that are responsible for controlling speech/voice.
What do spasmodic dysphonia symptoms look like?
Spasmodic dysphonia is characterized by involuntary spasms of the muscles that open or close the vocal folds, causing a voice that presents with breaks and strained/strangled quality or breathy quality, depending on the type of spasmodic dysphonia (adductor or abductor). Symptoms include voice breaks (voice “cutting off”) that can either be harsh and strained (Adductor type) or breath (abductor type). Typically there will be no symptoms with other type of non-speech vocalizations (crying, laughing, shouting, even singing). This is thought to be a result of the mammalian vocalization versus speech production that uses different pathways in the brain.
What causes spasmodic dysphonia?
That is the million dollar question! Researchers are working hard to figure this out exactly. We don’t yet know exact risk factors for development of SD. What we know so far:
SD seems more frequent in persons of European descent (Ludlow, et al., 2008)
It is more prevalent in females than in males
About 30% of individuals with SD report either an upper respiratory infection or major life stressor prior to onset (however, it is unclear how accurate this percentage is due to the possibility of recall bias)
About 10% have a family history of dystonia (not specifically SD)- however, a genetic link for SD has not been identified
It is hypothesized that the onset of SD may occur due to the interaction of a genetic predisposition, with environmental factors
Symptoms are rarely caused by brain injury
How do I know if I have spasmodic dysphonia?
Some voice disorders present similarly or present together (i.e. tremor, spasmodic dysphonia, and muscle tension dysphonia) and need to be differentially diagnosed. In order to know if you truly have spasmodic dysphonia you should go to an otolaryngologist. This is someone who is a specialized ENT (Ear, nose, throat doctor) but who focuses just on the larynx and your voice. Typically a speech pathologist may also be present during the initial evaluation and can help to differentially diagnose.
Generally, an otolaryngologist (ENT) and speech language pathologist will do a comprehensive evaluation, which includes collection of medical history, review of current and onset of symptoms, visualization of vocal fold movement through a stroboscopy exam (an endoscopy through the nose or mouth with a special camera and light which permits detailed visualization of vocal fold vibration), ratings of different voice qualities (i.e. overall severity, breaks, roughness, strain, breathiness), a recording of the voice to obtain acoustic (sound-based) measures, and aerodynamic evaluation to provide more information to the functioning and coordination of the voice mechanism. Palpation of the neck may be included to determine the presence of tension in and around the larynx. The individual may also be asked to read or repeat several specific sentences to aid in proper diagnosis.
Different sentence probes may be used to help differentiate the type of SD present. Adductor spasmodic dysphonia results from spasms in the muscles that close (adduct) the vocal folds and presents with phonation breaks after voiced consonants and in words that are started with a vowel. Abductor SD results from spasms in the muscles that open (abduct) the vocal folds and presents with breathy breaks after voiceless consonants (/p/, /t/, /k/, /h/). Some individuals may have aspects of both types, and may be diagnosed with the mixed type of spasmodic dysphonia.
Adductor Sentence Probe Examples
Count from 80 to 89
We eat eels every day
We mow our lawn all day
Where were you a year ago?
We eat eggs every Easter
Abductor Sentence Probe Examples
Count from 60 to 69
The puppy bit the tape
Peter will keep at the peak
How hard did he hit him?
Boys were singing songs outside of our house
Often times a neurologist is helpful in identifying comorbid neurological diagnoses (i.e. other dystonia), however, some are not as familiar with spasmodic dysphonia and the best way to get a definitive diagnosis, differentiated from other similar voice disorders, is from an otolaryngologist and speech language pathologist together.
Where should I find an otolaryngologist and a Speech Language Pathologist specialized in SD?
Otolaryngologists typically work in a voice center, hospital, or outpatient clinic. He/she may work with a speech pathologist on staff. The NSDA website has a good listing of otolaryngologists who specialize in SD. Some otolaryngologists will work directly with speech language pathologist, specialized in the treatment of voice. Some may refer out. If you are interested in services I provide please contact firstname.lastname@example.org for a free consultation.
Is it easy to get diagnosed?
The short answer is, unfortunately, no! Many individuals often see several providers before arriving at a correct diagnosis. This can often take months or even years for some patients! One of the important factors in this is starting off with the right provider (otolaryngologist and speech language pathologist/voice therapist who are specialized in SD). It can even be difficult sometimes for very skilled and specialized otolaryngologists and speech language pathologists to differentiate between spasmodic dysphonia, muscle tension dysphonia, and tremor. Sometimes these disorders can present similarly or mask symptoms of one another.
For information on treatment visit our Spasmodic Dysphonia Treatment post.