eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Laryngology

Laryngeal Manifestations of Parkinson Disease

Author: Thomas L Carroll, MD, Assistant Professor, Department of Otolaryngology-Head and Neck Surgery, Tufts Medical Center, Tufts University School of Medicine
Coauthor(s): Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine; Lorraine Ramig, PhD, Professor, Department of Speech Language Hearing Sciences, University of Colorado at Boulder; Senior Scientist, National Center for Voice and Speech (NCVS); Adjunct Professor, Department of Biobehavior, Columbia University Teacher's College
Contributor Information and Disclosures

Updated: Oct 7, 2009

Introduction

Background

First described by James Parkinson in 1817, parkinsonism is a neurological syndrome that manifests as a combination of bradykinesia, rigidity, resting tremor, and loss of postural reflexes. For the diagnosis of parkinsonism to be made, at least 2 of these features should be present, with one of the two being either rigidity or tremor.

The cause of parkinsonism can be divided into the following 3 areas:

• Idiopathic Parkinson disease (IPD) is the most common form and serves as the focus of this article.
• Secondary Parkinson disease includes the features of IPD but has an identifiable cause such as a medication's side effect, a head trauma, or a tumor.
• Parkinsonism-plus syndromes (PPS) include diseases in which the symptoms of IPD have a known genetic defect or distinctive pathologic changes such as multiple system atrophy, corticobasal ganglionic degeneration, or progressive supranuclear palsy.

IPD often begins insidiously, with tremor as the first presenting symptom. The tremor is first seen in the distal parts of the extremities and in the lips and is commonly described as "pill rolling" in the hands. Unlike other tremors, the extremity tremors cease upon active limb movement. Bradykinesia (masked facies, drooling, decreased blinking, shuffling gate, trouble with transfers from chairs and automobiles, difficulty with dexterous hand movements), rigidity (resistance to passive movement), and loss of postural reflexes (leading to a tendency to fall, stooped posture, and festination) all contribute to the morbidity associated with IPD. Interestingly, patients with IPD and their families often report reduced ability to communicate as the most significant associated problem.

Most patients with IPD do not recognize the problems that need to be overcome for them to effectively communicate; these problems include decreased neural drive to the larynx muscles, decreased sensory feedback that allows vocal shortcoming correction, and difficulty internally generating an acceptable speech volume. Treatments for IPD, including neuropharmacological and neurosurgical methods, offer effective therapy for limb symptoms, but their effects on vocal symptoms are not consistently or significantly effective and are not as well studied. Speech therapy is effective in treating the laryngeal manifestations of IPD.

Pathophysiology

Parkinson disease is primarily a result of the loss of pigmented dopaminergic neurons in the substantia nigra. Lewy bodies, eosinophilic inclusions in the cytoplasm of intact neurons, are often present. Lewy bodies are characteristic but not pathognomonic of IPD. A loss of dopamine allows an increased inhibitory output from the globus pallidus, causing the hypokinetic symptoms.

Frequency

United States

IPD is the most common movement disorder in patients older than 55 years. The incidence is estimated to be 4.5-21 cases per 100,000 persons per year. The prevalence is estimated to be 120 per 100,000 persons. Prevalence increases with age.

Sex

IPD is 1.5 times more common in men than in women.

Age

The average age of onset is in the seventh decade of life.

Clinical

History

A complete neurolaryngological evaluation must be completed. This includes a detailed history, evaluation of the voice, neurolaryngeal evaluation, and stroboscopy.

Patients are usually diagnosed with idiopathic Parkinson disease (IPD) before examination, although some patients are diagnosed based on their presenting vocal symptoms. The physician evaluating the voice must be vigilant about the possibility of IPD in patients who do not yet carry the diagnosis, and physicians should refer to a neurologist appropriately. As with any other medical history, discovering the nature of the symptoms (including when the symptoms began, if anything improves or worsens the symptoms, if the symptoms fluctuate, or if the symptoms are constant) is important. Particularly in patients with IPD, the physician must elicit the frustrations that the patient and patient's family are experiencing. Often, rather than recognizing their vocal shortcomings, patients feel like those around them are not listening or are becoming hard of hearing.

Evaluation of the voice 

• As the patient is speaking, the vocal loudness, intonation, and vocal quality, including fluidity of speech and articulation, should be assessed. Sustaining vowel phonation (eg, "ah") for maximum duration, counting to 50, and reading passages such as the rainbow passage provide reasonable speech samples. Closely listening for reduced and diminishing loudness and intonation and increasing breathiness and hoarseness helps to differentiate IPD from hyperkinetic disorders such as spasmodic dysphonia.¹  
• A soft, monotone voice, vocal tremor, poor articulation, variable speech rate, trouble with the initiation of speech, stutteringlike qualities, and masked facies or flat affect are all characteristics of IPD. Perhaps the most telling vocal symptom is the marked contrast in vocal loudness between habitual loudness (soft and diminishing) and the patient's response to a request to increase loudness. A request to "say that again, twice as loud" often results in increased loudness, improved voice quality, and a dramatic improvement in speech intelligibility.
• Neurolaryngeal examination
  • Because distortion can occur when the tongue is held forward during rigid stroboscopy, the neurolaryngeal examination is best performed by viewing the larynx with a flexible laryngoscope. The larynx is evaluated for vocal fold mobility, paresis or paralysis, coordination of movement, agility, fatigability, flexibility, and use of accessory muscles during phonation while the patient says various phrases and syllables. Hyperfunctional and hypofunctional disorders can often be differentiated by isolating the abductor and adductor muscle groups. The larynx is also visualized at rest. Perez et al found that vocal tremor is present in 55% of patients with IPD.² They found that only 35% of patients with IPD exhibit a resting tremor, while the remainder exhibited kinetic tremor (a goal-directed movement tremor). The tremor is primarily a vertical laryngeal movement. This is somewhat unexpected because limb tremor in IPD is usually a resting tremor and not a kinetic tremor.
  • Parkinson-plus syndromes (PPS) are found to carry a higher incidence of tremor (64%). Most tremors are located in the arytenoids. Perez et al found no vertical laryngeal tremor in patients with PPS.²
• Stroboscopy: Rigid stroboscopy plays a key role in the assessment of the vibratory characteristics of the vocal folds, including the presence of masses, lesions, or scar and glottic configuration abnormalities, including an elliptical closure pattern, phase asymmetry, and abnormal phase closure. Stroboscopy and neurolaryngeal examination are complementary in the evaluation of the patient with IPD. Common stroboscopy findings in IPD include true vocal fold atrophy or other evidence of glottal incompetence, including a chasing wave or a shorter closed phase. Pooling of secretions, decreased sensation, and aspiration are also characterizations of the IPD larynx. A paralyzed vocal fold suggests PPS as the etiology for the parkinsonism if other aspects of the diagnosis are present.

Causes

Most cases of IPD are believed to be caused by a combination of genetic and environmental factors.

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