Spasmodic dysphonia is a rare neurological disorder that causes involuntary muscle contractions in the larynx. It affects speech by disrupting phonation and causes symptoms like a strained, breathy, or whispery voice. The condition is classified as adductor or abductor spasmodic dysphonia depending on the affected muscles. While the exact cause is unclear, risk factors include genetics and environmental triggers. Treatment involves botulinum toxin injections into the larynx muscles or voice therapy, with the goal of reducing muscle spasms and improving speech.

1. Spasmodic Dysphonia
Ade Wijaya, MD

2. Outline:
• Introduction
• Classification
• Anatomy
• Epidemiololy
• Risk Factors
• Pathophysiology
• Clinical Evaluation
• Differential Diagnosis
• Treatment
• Summary

3. Introduction
• Uncommon neurological disorder of the larynx that affects ∼1 in 100,000
individuals
• Chronic involuntary muscle contraction of the intrinsic laryngeal muscles,
leading to action-specific disruptions in phonation
• The condition can involve the larynx alone, or it can be associated with a
spectrum of head and neck dystonias such as blepharospasm, torticollis,
hemifacial spasm, cervical dystonia, and Meige syndrome (blepharospasm
and oromandibular dystonia)
• ≈ laryngeal dystonia
Nutt JG, Muenter MD, Aronson A, et al. Epidemiology of focal and generalized dystonia in Rochester, Minnestoa. Mov Disord. 1988;3:188–194.
Marsden CD, Sheehy MP. Spastic dysphonia, Meige disease and torsion dystonia. Neurology. 1982;32:1202–1203.

4. Classification
Adductor
(80 %)
abductor
M
I
X
E
D
Blitzer A, Brin MF, Fahn S, et al. Clinical and laboratory characteristics of focal laryngeal dystonia: study of 110 cases. Laryngoscope. 1988;98:636–640

5. Anatomy
Chen DW, Ongkasuwan J. Spasmodic dysphonia. International ophthalmology clinics. 2018 Jan 1;58(1):77-87.

6. Epidemiology
• F:M = 2:1
• 4th -6th decade
• It may occur in patients with underlying neuromuscular disorders.
Chen DW, Ongkasuwan J. Spasmodic dysphonia. International ophthalmology clinics. 2018 Jan 1;58(1):77-87.

7. Risk Factors
• Genetic
• Environment
• Family history
• Autosomal dominant inheritance patterns in some cases
• Genes related to parkinsonism
• Psychologic factors
Chen DW, Ongkasuwan J. Spasmodic dysphonia. International ophthalmology clinics. 2018 Jan 1;58(1):77-87.

8. Pathophysiology
• Unclear
• Lesions of the brainstem and basal ganglia (?)
3 possible mechanism:
- Decreased inhibition of intracortical processes
- Increased plasticity leading to heightened response to repetitive activity
- Sensory abnormalities resulting in disordered motor output
Chen DW, Ongkasuwan J. Spasmodic dysphonia. International ophthalmology clinics. 2018 Jan 1;58(1):77-87.

9. Clinical Evaluation
• Singing, whispering, and spontaneous emotional actions such as crying and
laughing may be normal in patients with spasmodic dysphonia
• Patients can present with difficulty reading a new passage, and symptoms
often worsen with stress
• 30 %  progressive
Tanner K, Roy N, Merrill RM, et al. Spasmodic dysphonia: onset, course, socioemotional effects, and treatment response. Ann Otol Rhinol Laryngol. 2011;120:465–473
Braden MN, Hapner ER. Listening: the key to diagnosing spasmodic dysphonia. ORL Head Neck Nursing. 2008;26:8–12.

10. Adductor Spasmodic Dysphonia
• Lead to the vocal folds closing tightly, resulting in a strained or tight voice and
cessation of airflow
• The spasms are best elicited when the vocal folds are approximating, for
example, with vowels and voiced consonants such as /b/, /d/, /g/, and /m/
• Speech would sound strangled with premature breaks due to glottic closure
Chen DW, Ongkasuwan J. Spasmodic dysphonia. International ophthalmology clinics. 2018 Jan 1;58(1):77-87.

11. Abductor Spasmodic Dysphonia
• Spasm of the posterior cricoarytenoid muscle, the only abductor muscle of
the larynx
• A breathy or whisper-like voice
• The involuntary opening of the vocal folds causes excessive airflow to escape
and loss of vocalization.
• Patients have difficulty with /h/, /s/, /f/, /P/, /t/, and /k/.
Chen DW, Ongkasuwan J. Spasmodic dysphonia. International ophthalmology clinics. 2018 Jan 1;58(1):77-87.

12. Chen DW, Ongkasuwan J. Spasmodic dysphonia. International ophthalmology clinics. 2018 Jan 1;58(1):77-87.

13. Differential Diagnosis
• Muscle tension dysphonia (MTD)
Strained or breathy voice that is consistently present throughout all vocal tasks.
• Essential tremor
• Parkinson Disease (PD)
• Spastic dysarthria
Chen DW, Ongkasuwan J. Spasmodic dysphonia. International ophthalmology clinics. 2018 Jan 1;58(1):77-87.

14. Treatment
• Botulinum toxin injection (adductor spasmodic dysphonia)
• Voice therapy
• Surgical treatment
Chen DW, Ongkasuwan J. Spasmodic dysphonia. International ophthalmology clinics. 2018 Jan 1;58(1):77-87.
French, G., Bosch, J.D. & Randall, D.R. Retrospective review of dosing trends in botulinum toxin injections for the treatment of adductor spasmodic
dysphonia in a long-term cohort. J of Otolaryngol - Head & Neck Surg 49, 4 (2020). https://doi.org/10.1186/s40463-020-0401-4

15. Summary
• Is a focal laryngeal dystonia
• Singing, whispering, and spontaneous emotional actions such as crying and
laughing may be normal in patients with spasmodic dysphonia
• Botulinum injection

16. THANK YOU