• Ludlow (1995) - defines spasmodic dysphonia as a focal dystonia affecting the laryngeal muscle control during speec
• Exact site of lesion and cause is not known - may be in basal ganglia
• At one time, etiology thought to be psychogenic
• Stress does seem to exacerbate symptoms; therapy can sometimes alleviate symptoms

• Affects men & women in equal numbers
• Onset often in middle age
• Onset is variable
• Associated with URI
• Traumatic event
• Slow insidious process progressing from hoarseness to interrupted phonation
• Symptoms absent in vegetative function & in speech that does not require phonation

• Spasm or sudden contraction of laryngeal musculature causes sudden closure (adduction) of vocal folds
• Struggle/strain to talk with intermittent voice arrests
• Varying degrees of hoarseness, harshness, tremor or creaking, choked, tense, squeezed voice
• Loudness & pitch variations, intermittent aphonia

• Intermittent episodes of breathy dysphonia
• Sudden drops in pitch
• Vowel prolongations
• Delay in voice onset after voiceless productions
• Difficulty with transitions from voiceless to voiced phonemes

• Voice symptoms similar to:
• Vocal abuse/misuse dysphonia
• Psychogenic dysphonia
• Muscle Tension Dysphonia (MTD)
• Differences
• SD is not intermittent - never goes away completely
• Onset is gradual
• Abrupt voice breaks are common
• Voice better in AM (dystonias go away during sleep)
• Not apparent during singing
• Voice may improve when using alcoholic beverages
• Can be distinguished from MTD spectrally

Treatment

• Very resistant to treatment including  voice therapy
• Recurrent laryngeal nerve section
• 5 years after surgery SD recurs in over 50%
• Dystonia either resets or worsens in unoperated side
• Anterior laryngoplasty & vocal fold thinning
• Some positive results with circumlaryngeal massage but effects temporary
• Treatment of choice is Botox

Botox Treatment

• Adductor SD receives bilateral or unilateral injections in TA
• Post-injection voice is mildly breathy followed by 2-6 months of complete relief
• Abductor SD requires bilateral injections into PCA
• Requires injections more frequently (every 3-4 months)
• Subtypes - those with mixed dystonias & those with tremor do not respond as well to Botox

• Bilateral - results in aphonia & vulnerable open airway
• Swallowing therapy to protect airway
• Tracheotomy for severe cases
• Unilateral - breathy, dysphonic or aphonic voice
• Spontaneous recovery in cases of trauma in first 8 months post-onset
• Temporary solutions for better voice include using higher pitch, masking to increase effort & intensity, digital manipulation and head position
• Injections of paralyzed vocal fold including fat, Teflon, collagen
• Thyroplasty, nerve grafts
• Amplification

•  Includes bowing, paralyzed or weak vocal folds associated with neurogenic disease (Parkinson's)
•  Use of reflexive behaviors that result in closure including coughing throat clearing, grunting, laughing
•  Pushing, pulling, isometrics during phonation
•  Vocal function exercises
•  Lee Silverman Voice Therapy
•  Improve function of other valves to compensate (articulatory precision, oral resonance)