Significant variability exists regarding the terminology used to describe vocal fold motion impairment (no or reduced motion) in the literature and among the medical community. Terms such as vocal fold palsy, vocal fold immobility, vocal fold paralysis, vocal fold paresis, and hemilaryngeal palsy are at times used interchangeably, or at other times, the same term is used to represent different findings among clinicians. This confusion is present for both unilateral vocal fold motion abnormalities and bilateral vocal fold motion problems. As a result of the lack of consensus on specific nomenclature, communication with patients and between clinicians is impaired. In addition, research findings from different institutions are difficult to interpret or compare due to this confusion in terms. The establishment of precise nomenclature to describe vocal fold motion impairment will lead to a better understanding of the patient’s clinical picture and facilitate future research in the field of vocal fold motion impairment.

The authors recognize a need for a defined nomenclature to describe vocal fold motion abnormality. It is beyond the purview of this chapter to discuss the diagnostic criteria for each term in detail—details will be discussed in Chaps. 4, 5, and 6. This chapter will also not discuss the topics of inappropriate vocal fold motion that can occur in certain conditions, such as paradoxical vocal fold motion disorder or vocal cord dysfunction [1, 2]. In addition, this chapter will not discuss hyperkinetic vocal fold motion diseases such as spasmodic dysphonia or essential tremor of the larynx. Furthermore, the focus of this project is limited to the true vocal fold(s) and not supraglottic structures. What follows are definition of terms which we advocate to be used for description of vocal fold motion impairment: vocal fold immobility, vocal fold paralysis, vocal fold hypomobility, and vocal fold paresis. We provide definitions and descriptions for each of these terms.

Descriptions of vocal fold motion typically reflect motion of the full length of the vocal fold, rather than the individual components (i.e., cartilaginous vs. membranous). It is often best to focus one’s attention on vocal fold motion at the location of the vocal process of the arytenoid cartilage during adductory or abductory tasks (phonation, cough, Valsalva, sniffing, inspiration, etc.). For this proposal, vocal fold motion also strictly refers to only motion of the vocal fold (level of the glottis) and, thus, does not include motion of any aspect of the supraglottis (false vocal fold, petiole nor supraglottic portion of the arytenoid cartilages).

Movement of the vocal fold is completely different from movement of the “mucosal wave” of the vocal fold. Thus, none of the terms discussed in this proposal pertain to mucosal vibration or pliability that is typically assessed with stroboscopy (or high-speed video). Misinterpretation of “vocal fold motion” can occur when the mucosa of the vocal fold is seen to “move” because of the Bernoulli effect during inhalation. This does not constitute substantive, purposeful vocal fold motion. Likewise, mucosal wave vibration seen during phonation (using stroboscopy) does not provide evidence of purposeful vocal fold motion.

Vocal fold motion determination can be made with a variety of laryngeal visualization methods (mirror, flexible, or rigid endoscopes) on awake individuals, not involving vocal fold palpation (i.e., direct laryngoscopy). Vocal fold motion determination can also be made during general anesthesia with the patient breathing spontaneously.

Determination of the vocal fold motion status should be done with the patient relaxed and comfortable (flexible endoscopy may be better than rigid or mirror endoscopy for this) and involves gross motion (visualization of purposeful vocal fold motion or an absence of such motion) seen during the actual exam. Flexible laryngoscopy has the vital benefit of allowing the patient to perform tasks of phonation and vegetative tasks (cough, laugh, respiration) in the most “natural” position. Peroral approaches to laryngeal visualization using an angled telescope can give greater magnification and excellent optical quality but involves a relatively “unnatural” position (tongue protrusion) which may or may not create an examination artifact. Proponents of the latter examination technique appropriately argue that if vocal fold motion is normal on a peroral examination, then no further examination is required. However, if there is any abnormality of vocal fold motion (speed or range of motion) seen on a rigid exam, then these findings should be confirmed or discarded by a trans-nasal flexible laryngoscopy evaluation. Often patients will display different degrees and/or patterns of motion with different tasks. Judgment of motion or amount of motion should be observed with a variety of tasks, especially with the patient performing tasks such as alternating between /i/ and sniff or vegetative tasks (cough, laugh, etc.). The best gross vocal fold motion that occurs consistently throughout the exam seen during any of the exam tasks should be used to make the final decision on motion (yes or no) and degree of motion impairment.

A vocal fold is immobile if there is no active or voluntary adduction or abduction on clinical examination. A hypomobile vocal fold has reduced range and/or speed of motion on either adductory or abductory tasks. These two terms describe the qualitative physical exam finding of vocal fold motion and makes no assumption of the etiology and thus the diagnosis for the impaired motion. The terms, vocal fold immobility and vocal fold hypomobility, should be used when a definitive etiology for the motion impairment has not been established. The use of this terminology does not imply an idiopathic status of the vocal fold motion impairment because its use informs the reader that all possible causes of the vocal fold motion impairment have not yet been fully evaluated. These terms are the ideal terms for description of the results of the physical examination of the vocal folds (preferably via flexible laryngoscopy). When vocal fold hypomobility is seen on flexible laryngoscopy, further description of degree of vocal fold hypomobility (mild, moderate, or severe), description of the speed of vocal fold motion (reduced, normal, etc.), and/or description of the range of motion assessed (decreased or normal) can be used as subjective descriptors of the examiner’s physical exam findings. None of these descriptors have been validated to date, but they do play an important role in the clinical description of the vocal fold motion assessment.

The terms vocal fold paralysis and vocal fold paresis indicate a neurologic etiology of the vocal fold motion abnormality seen on physical examination.