Vocal Tremor

Author Credentials 

Maya G. Sardesai, MD, MEd
Assistant Professor
Department of Otolaryngology – Head & Neck Surgery
University of Washington
Seattle, WA
sardesai@uw.edu

Module Summary

Laryngeal or voice tremor can occur independently or as a manifestation of several neurological conditions including essential tremor, Parkinson disease, and so-called Parkinson-plus syndromes. Around 25-30% of patients with essential tremor will have laryngeal involvement, and about half of cases are inherited in autosomal dominant fashion with 100% penetrance. Patients present in a bimodal distribution in the 2nd and 6th decades, with 10% of patients over 65 having symptoms. The diagnosis is primarily clinical, and should be determined after thorough evaluation of the head-and-neck, extremities and laryngoscopy to identify and exclude other conditions. Laryngoscopy may identify a 4-10 Hz tremor, involving the intra- and/or extra-laryngeal musculature, but there may be considerable variation in the range of frequencies. Imaging and EMG are not required to establish the diagnosis. Symptoms may improve with consumption of alcohol, and voice therapy may be helpful in some cases. Medical treatment options include propranolol, primidone, and methazolamide, though the effectiveness is about 50% in each case. Botulinum toxin injection into one or both thyroarytenoid muscles has been shown to reduce the amplitude of the tremor and thus improve symptoms in 67-80% of cases. Thalamic deep brain stimulation (DBS) can be effective but can carry significant risks including dysarthria.

Module Learning Objectives 
  1. Identify the anatomy and physiology associated with vocal tremor.
  2. Explain the appropriate initial evaluation of patients presenting with vocal tremor, including appropriate history, associated symptoms and physical examination.
  3. Describe the typical endoscopic and videostroboscopic findings in patients with vocal tremor.
  4. List several other conditions in the differential diagnosis for patients presenting with presumed vocal tremor.
  5. Summarize the benefits and limitations of investigations for evaluation of vocal tremor.
  6. Cite common pharmacological treatment options for vocal tremor.
  7. Describe the expectations, limitations, risks, and benefits of botulinum toxin treatment for vocal tremor.
  8. Review some surgical treatment options for vocal tremor.

Anatomy

Learning Objectives 
  1. Describe the anatomy of the thyroarytenoid muscles, interarytenoid muscles, lateral and posterior cricoarytenoid muscles.
  2. Explain the role of the extrapyramidal system and cerebellum in the control of laryngeal musculature
  3. Describe the extralaryngeal musculature that may be involved in patients presenting with vocal tremor.
References 
  1. Standring S.The Anatomical Basis of Clinical Practice. Gray’s Anatomy. 40th. Philadelphia: Churchill Livingstone; 2008.
  2. Merati AL, Bielamowicz SA.Textbook of Laryngology. San Diego: Plural Publishing Inc; 2006.
  3. Hillel AD. The study of laryngeal muscle activity in normal human subjects and in patients with laryngeal dystonia using multiple fine-wire electromyography. Laryngoscope. 2001 Apr;111(4 Pt 2 Suppl 97):1-47.

Pathogenesis

Learning Objectives 

Explain in general terms the following theories regarding the pathophysiology of vocal tremor: neurodegeneration hypothesis, gamma-aminobutyric acid (GABA) hypothesis, oscillating network hypothesis.

References 
  1. Helmich RC, Toni I, Deuschl G, Bloem BR. The pathophysiology of essential tremor and Parkinson's tremor. Curr Neurol Neurosci Rep. 2013 Sep;13(9):378.

Basic Science

Learning Objectives 

Describe the role of dopamine, norepinephrine, serotonin, and gamma-aminobutyric acid (GABA) in neuromuscular control.

References 
  1. Helmich RC, Toni I, Deuschl G, Bloem BR. The pathophysiology of essential tremor and Parkinson's tremor. Curr Neurol Neurosci Rep. 2013 Sep;13(9):378.

Incidence

Learning Objectives 
  1. Estimate the prevalence of vocal tremor in patients with essential tremor.
  2. Predict the prevalence of comorbid vocal tremor in patients with other conditions including laryngeal dystonia, Parkinson’s disease and Parkinson-plus syndromes
References 
  1. Merati AL, Heman-Ackah YD, Abaza M, Altman KW, Sulica L, Belamowicz S. Common movement disorders affecting the larynx: a report from the neurolaryngology committee of the AAO-HNS. Otolaryngol Head Neck Surg. 2005 Nov;133(5):654-65.
  2. Wolraich D, Vasile Marchis-Crisan C, Redding N, Khella SL, Mirza N. Laryngeal tremor: co-occurrence with other movement disorders. ORL J Otorhinolaryngol Relat Spec. 2010. 72(5):291-4.

Genetics

Learning Objectives 

Describe the inheritance of essential tremor.

References 
  1. Merati AL, Heman-Ackah YD, Abaza M, Altman KW, Sulica L, Belamowicz S. Common movement disorders affecting the larynx: a report from the neurolaryngology committee of the AAO-HNS. Otolaryngol Head Neck Surg. 2005 Nov;133(5):654-65.

Patient Evaluation

Learning Objectives 
  1. Describe the appropriate history of present illness, associated symptoms, risk factors, and past medical history indicated for proper initial evaluation of a patient with vocal tremor.
  2. Describe the appropriate physical examination including upper and lower motor neuron signs that may be identified in patients presenting for evaluation of vocal tremor.
  3. Describe the characteristic laryngoscopic and stroboscopic findings seen in patients with laryngeal tremor.
References 
  1. Merati AL, Heman-Ackah YD, Abaza M, Altman KW, Sulica L, Belamowicz S. Common movement disorders affecting the larynx: a report from the neurolaryngology committee of the AAO-HNS. Otolaryngol Head Neck Surg. 2005 Nov;133(5):654-65.

Imaging

Learning Objectives 
  1. Describe some common EMG findings in patients with vocal tremor.
  2. Explain the limitations and overall role of laryngeal EMG in evaluation of patients with vocal tremor.
References 
  1. Koda J, Ludlow CL. An evaluation of laryngeal muscle activation in patients with voice tremor. Otolaryngol Head Neck Surg. 1992;107:684–696.
  2. Blitzer A, Crumley RL, Dailey SH, Ford CN, Floeter MK, Hillel AD, Hoffmann HT, Ludlow CL, Merati A, Munin MC, Robinson LR, Rosen C, Saxon KG, Sulica L, Thibeault SL, Titze I, Woo P, Woodson GE. Recommendations of the Neurolaryngology Study Group on laryngeal electromyography. Otolaryngol Head Neck Surg. 2009 Jun;140(6):782-793.

Treatment

Learning Objectives 

Describe the range of treatment options from conservative management to pharmacological, procedural, and surgical intervention.

References 
  1. Merati AL, Heman-Ackah YD, Abaza M, Altman KW, Sulica L, Belamowicz S. Common movement disorders affecting the larynx: a report from the neurolaryngology committee of the AAO-HNS. Otolaryngol Head Neck Surg. 2005 Nov;133(5):654-65.

Medical Therapies

Learning Objectives 

Describe the role of voice therapy in management of vocal tremor.

References 
  1. Barkmeier-Kraemer J, Lato A, Wiley K. Development of a speech treatment program for a client with essential vocal tremor. Semin Speech Lang. 2011 Feb. 32(1):43-57.

Pharmacology

Learning Objectives 
  1. Describe the limitations, risks, benefits and role of Beta-adrenergic blockers, primidone, and methazolamide in the management of vocal tremor.
  2. Describe the limitations, risks, benefits and role of Beta-adrenergic blockers in the management of vocal tremor.
References 
  1. Merati AL, Heman-Ackah YD, Abaza M, Altman KW, Sulica L, Belamowicz S. Common movement disorders affecting the larynx: a report from the neurolaryngology committee of the AAO-HNS. Otolaryngol Head Neck Surg. 2005 Nov;133(5):654-65.
  2. Nida A, Alston J, Schweinfurth J. Primidone Therapy for Essential Vocal Tremor. JAMA Otolaryngol Head Neck Surg. 2015 Dec 10;1-5.
  3. Busenbark K, Ramig L, Dromey C, Koller WC. Methazolamide for essential voice tremor. Neurology. 1996 Nov;47(5):1331-2.

Surgical Therapies

Learning Objectives 
  1. Describe the expectations, limitations, risks and benefits of botulinum toxin for management of vocal tremor
  2. Describe the expectations, limitations, risks and benefits of deep brain stimulation for management of vocal tremor
References 
  1. Merati AL, Heman-Ackah YD, Abaza M, Altman KW, Sulica L, Belamowicz S. Common movement disorders affecting the larynx: a report from the neurolaryngology committee of the AAO-HNS. Otolaryngol Head Neck Surg. 2005 Nov;133(5):654-65.

Staging

Learning Objectives 

Describe one validated tool for scoring the severity of vocal tremor.

References 
  1. Bové M, Daamen N, Rosen C, Wang CC, Sulica L, Gartner-Schmidt J. Development and validation of the vocal tremor scoring system. Laryngoscope. 2006 Sep;116(9):1662-7.

Case Studies

  1. A 70 yo woman presents with a two-year history of gradual-onset, slowly worsening hoarseness that improves when she drinks a glass of wine. She also notes some hand tremor, particularly with directed movement. Her older sister has a similar condition and has been receiving regular botulinum toxin injections for years with good results. Her granddaughter who is twenty-one has begun to notice some tremor in her hands also. The patient is not interested in surgical or procedural interventions.
    • How would you counsel the patient about treatment options, risks and benefits?
    • What is her overall prognosis?
  2. The patient’s sister who is 75 years old and has been receiving botulinum toxin injections for years with good results but is concerned about the long-term effects. She is interested in exploring permanent surgical treatment options. She has read about deep brain stimulation (DBS) and would like to hear your opinion and recommendations.
    • What are the long-term effects of botulinum toxin in this setting?
    • What are permanent treatment options?
    • What are the expectations, limitations, risks, and benefits of DBS?
References 
  1. Merati AL, Heman-Ackah YD, Abaza M, Altman KW, Sulica L, Belamowicz S. Common movement disorders affecting the larynx: a report from the neurolaryngology committee of the AAO-HNS. Otolaryngol Head Neck Surg. 2005 Nov;133(5):654-65.

Complications

Learning Objectives 
  1. Describe the adverse effects and complications of propranolol, primidone, and methazolamide.
  2. Describe the complications of botulinum toxin injection in the larynx.
  3. Describe the complications of DBS surgery.
References 
  1. Nida A, Alston J, Schweinfurth J. Primidone Therapy for Essential Vocal Tremor. JAMA Otolaryngol Head Neck Surg. 2015 Dec 10;1-5.
  2. Busenbark K, Ramig L, Dromey C, Koller WC. Methazolamide for essential voice tremor. Neurology. 1996 Nov;47(5):1331-2.
  3. Adler CH, Bansberg SF, Hentz JG. Botulinum toxin type A for treating voice tremor. Arch Neurol. 2004 Sep;61(9):1416-20.

Review

Review Questions 
  1. How common is vocal tremor?
  2. How is vocal tremor diagnosed?
  3. What are associated symptoms?
  4. Is vocal tremor inherited?
  5. What are medical treatment options?
  6. How effective is Botulinum toxin for treatment of vocal tremor?
  7. What are the risks of botulinum toxin treatment?
  8. What surgical options are available and what are the risks?
References 
  1. Merati AL, Heman-Ackah YD, Abaza M, Altman KW, Sulica L, Belamowicz S. Common movement disorders affecting the larynx: a report from the neurolaryngology committee of the AAO-HNS. Otolaryngol Head Neck Surg. 2005 Nov;133(5):654-65
Resources 

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