Spasmodic Dysphonia Workup

Updated: Feb 09, 2021
  • Author: Michael J Pitman, MD; Chief Editor: Arlen D Meyers, MD, MBA  more...
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Laboratory Studies

Laboratory tests are generally unnecessary.


Imaging Studies

Reserve brain imaging (computed tomography [CT] scanning with gadolinium or magnetic resonance imaging [MRI]) for patients with focal findings upon neurologic examination that are beyond the distribution of spasmodic dysphonia (SD).


Other Tests

A study by Creighton et al indicated that the diagnosis of spasmodic dysphonia can be delayed by years owing to a lack of physician awareness of the condition and the need for well-defined diagnostic criteria. The study, in which 107 patients with spasmodic dysphonia answered questionnaires concerning diagnosis and treatment, found that diagnosis of the condition took an average of 4.43 years after patients first saw a physician for vocal symptoms. Patients also required visits to an average of 3.95 physicians before receiving the correct diagnosis. [20]

Neurologic examination

The occurrence of other neurologic signs not associated with other dystonias or tremor suggests that spasmodic dysphonia (SD) is secondary to another disease process. The neurologic examination may also reveal signs of other neurologic disorders that may be misconstrued as spasmodic dysphonia (SD).

Perceptual analysis

Grade, roughness, breathiness, atonicity, and strain (GRBAS) is the evaluation system currently used to evaluate perceptual judgment. GRBAS involves a scale of 0-3 (0 = normal or absence of deviance; 1 = slight deviance; 2 = moderate deviance; 3 = severe deviance).

Conversational speech or the reading of a passage is rated. The classic perceptual sign of spasmodic dysphonia (SD) is abnormal voice quality that is heard in contextual speech but not necessarily in singing, whispering, laughing, falsetto voice, or crying.

Sentences that elicit adductor breaks when spoken include the following:

  • "I eat apples and eggs."

  • "The dog dug a new bone."

  • "We mow our lawn all year."

  • "Early one morning, a man and a woman were ambling along a 1-mile lane, running near Rainy Island Avenue."

Sentences that elicit abductor breaks when spoken include the following:

  • "How high is Harry's hat?"

  • "Did he go to the right or to the left?"

  • "When he comes home, we'll feed him."

  • "He saw half a shape mystically cross a simple path, at least 50 or 60 steps in front of his sister Kathy's house."

Acoustic analysis

Acoustic measures reflect the status of vocal function. Standard deviation of the fundamental frequency or jitter (measured in ms) and amplitude modulation or shimmer are significantly higher in patients with spasmodic dysphonia (SD). The signal-to-noise ratio is generally lower in patients with spasmodic dysphonia (SD) than in healthy control subjects.

Aerodynamic analysis

Aerodynamic analysis of voice production includes the measurement of airflow and air pressure and their relationships during phonation.

In adductor spasmodic dysphonia (SD), mean airflow rates range from normal to extremely low.

In abductor spasmodic dysphonia (SD), mean phonatory airflow rate is generally above normal, with bursts of airflow occurring with the abductor spasm.

Subglottic pressure measures were estimated to be higher than normal in patients with adductor spasmodic dysphonia (SD).

Electromyographic analysis

In 2001, Hillel demonstrated that all the laryngeal muscles are involved in spasmodic dysphonia using examination with hooked wired electrodes. [21]

Either abductor or adductor muscle spasms are believed to predominate, resulting in the corresponding symptoms. EMG is generally not used in diagnosing spasmodic dysphonia (SD). In experienced hands, EMG guidance may not be necessary. [22]

Subjective evaluation by patient

The purpose of a subjective self-evaluation is to determine the deviance of voice quality and the severity of disability or handicap in daily professional and social life and to determine the possible emotional repercussions of the dysphonia.


Diagnostic Procedures


Videolaryngostroboscopy is the main clinical tool used in determining the origin of voice disorders. Abductor and adductor spasms can be visualized during voice breaks. This procedure can also be used to assess the quality of vocal fold vibration to evaluate treatment effectiveness.