Physical Examination of the Larynx and Videolaryngoscopy

Marshall E. Smith and Eiji Yanagisawa

It has been suggested that the laryngeal system can be regarded as a microcosm of the entire speech mechanism,1 and therefore the larynx may reflect neurologic impairments before other speech components. Neurologic voice disorders can be isolated problems or occur in the context of extensive systemic disease. Because voice disorders have been reported as initial symptoms of various neurologic disorders, such as Parkinson disease²and myasthenia gravis,^3–6 phonatory evaluation should be considered for its contribution to neurologic assessment.⁷The laryngologist, speech pathologist, and neurologist caring for these patients recognize several clinically important issues. They are aware of (1) disorders for which voice problems and complaints may initially present to the laryngologist or voice clinician; and (2) disorders for which medical, surgical, or behavioral intervention may improve laryngeal function, in the context of the individual’s general physical condition. These key considerations should not be minimized because voice characteristics may contribute to neurologic differential diagnosis, and various intervention procedures may significantly improve quality of life, even in a patient otherwise suffering from a terminal illness. An example that applies particularly to these issues is the patient with early symptoms of bulbar amyotrophic lateral sclerosis (ALS), presented in detail in an excellent review by Hillel et al.⁸

Physical Examination (Neurolaryngologic and Voice Evaluation)

The neurolaryngologic examination involves several components. These include medical history, phonation assessment, general otolaryngology–head and neck examination, laryngeal imaging examination, directed neurologic examination, and, when appropriate, special diagnostic testing. Aspects of the laryngeal imaging examination are discussed in further detail later in the chapter.

The physical examination of the larynx of a patient begins when the clinician observes the patient walk into the room. The examination proceeds while listening to the patient relate his or her complaints and details of medical history. While physicians are trained in observational skills, those caring for laryngeal disorders require use of the ears as well as the eyes. A careful history of both medical and neurologic symptoms provides the basis for evaluation of the patient with a neurologic voice disorder. The voice history includes the nature of the vocal complaint. In general, voice complaint symptoms may be described as hoarseness, vocal fatigue, breathiness, reduced phonation range, aphonia, pitch breaks or inappropriately high pitch, strain/strangle voice, and tremor.9 One or (frequently) several of these complaints may be given by a patient with a neurologic voice disorder. Voice problems in conjunction with other speech production difficulties such as unclear speech, slurring, or unintelligible speech suggest an underlying neurologic disease. The same applies to the presence of concomitant symptoms of dysphagia. The onset and progression of symptoms is elicited, as well as what improves and worsens the voice. Voice and speech problems that are intermittent do not suggest a neurologic disease. When underlying organic neuromotor disease is present, though symptoms may vary to some degree, the speech or the voice is usually not totally normal.¹⁰Stress worsens most neurologic voice disorders, so this should not be taken as an indication of purely functional etiology of symptoms. Other symptoms of laryngeal dysfunction, for example, swallowing or respiratory complaints, are reviewed; if these also occur, a neurologic disease may be suspected. The patient’s complete medication history is discussed. A review of systems pays particular attention to respiratory, gastrointestinal, endocrine, and neurologic areas. Questions about fatigue, balance, gait disturbance, tremor, changes in handwriting, sensation, and weakness all pertain to the neurologic system review.

The next portion of the examination comprises the phonation assessment. Ideally, it should be conducted jointly by a voice/speech pathologist and a laryngologist. Separately or together, they assess the quality of the patient’s voice, speech, resonance, articulation, prosody, and breath support. Such examination begins while listening as the patient relates his or her medical history. In addition, sustained vowel phonation allows evaluation of phonatory stability, tremor, and movement of laryngeal supporting structures. If the patient is a singer and has complaints related to singing, then observation of the patient while singing is mandatory so that the problem may be demonstrated. Professional vocalists may develop neurologic voice disorders; problems during the vocally demanding tasks of singing may be an initial symptom.11 Testing of the articulators (tongue, lip, jaw) can be done by having the patient rapidly repeat /pa/,/ta/,/ka/. Lack of precision or crispness suggests lower motor neuron or muscular compromise. Testing for velopharyngeal incompetence is done by asking the patient to sustain phonation of the vowels “ah” and “ee” while alternately pinching and releasing the nares together. The patient is also asked to read sentences with high pressure and nasal sounds such as “Suzy stayed all summer” or counting aloud from 60 to 70. Increased nasal resonance or nasal air emission during these tasks suggests lack of adequate velopharyngeal closure. Comprehensive assessment of the laryngeal mechanism in the context of motor speech control is summarized by Yorkston and Beukelman,¹²and in the textbook by Duffy.¹³

The general otolaryngologic–head and neck examination should be conducted, including assessment of ears, nasal passages, facial structures, oral cavity and oropharynx, nasopharynx, and neck inspection and palpation.

The patient with a neurologic voice disorder may have other neurologic examination findings that aid the physician in diagnosis. These have been reviewed in an excellent summary by Rosenfield et al.¹⁰Although this neurologic assessment may not replace a complete evaluation by a neurologist, it helps the laryngologist to understand the nature of the illness of which the voice may be only a part. It also facilitates communication with the neurologist about the patient’s problem. Components include a cranial nerve examination, assessment of muscle strength and tone (motor and extrapyramidal), and coordination (cerebellar). Though cranial nerve testing is familiar to the otolaryngologist, other aspects of neurologic examination are not. However, these should be routinely performed in cases of suspected neurologic voice disorders. In the elderly patient, a screening examination for tone (resistance to passive movement) may be more revealing than an assessment of muscle strength.¹⁴Increased tone on passive movement of the limbs may be an upper motor neuron sign, and rigidity of wrist or elbow movement may be an early sign of Parkinson disease. Coordination and cerebellar function are assessed by observation of gait and by the Romberg sign. Following the Romberg test, the coordination of the upper extremities is evaluated by finger-nose testing. Observation of the outstretched limbs allows evaluation of postural (cerebellar) tremor. Resting tremor that improves with movement is seen in Parkinson disease. During the examination the patient is observed for adventitious (unintended or involuntary) movements (e.g., tremor of head or limbs, circumoral twitches, blepharospasm, dyskinesias, or dystonias). Observation of the patient’s handwriting may be helpful in identifying ataxia or tremor.

Special diagnostic tests are indicated in selected cases. Laryngeal electromyography has been found to be helpful in the diagnostic assessment of vocal fold paralysis, differentiating paralysis from fixation, and in determining prognosis for recovery.^15–19 It can provide helpful information in determining etiology and treatment of a variety of neurolaryngologic disorders.²⁰The workup of vocal fold paralysis, in the absence of identifiable etiology, involves imaging studies along the entire course of the nerve on the affected side.²¹Regarding spasmodic dysphonia, in the absence of secondary causes for dystonia,^22,23 Rosenfield et al²⁴