Ann Otol Rhinal Laryngall00:1991

BILATERAL VOCAL FOLD MOTION IMPAIRMENT: PATHOPHYSIOLOGY AND MANAGEMENT BY TRANSVERSE CORDOTOMY HASKINS K. KASHIMA,

MD

BALTIMORE, MARYLAND

Although bilateral vocal fold paralysis (BVFP) is an uncommon disorder, bilateral vocal fold motion impairment (BVFMI) resulting from a variety of laryngeal derangements is encountered with increasing frequency. Moreover, pure BVFP accounts for only a small proportion of BVFMI. When antecedent factors associated with BVFP are absent, recognition of BVFMI is often delayed and frequently overlooked. The requirements for assessment and successful management of BVFMI are 1) recognition of its presence, 2) identification of the constituent factors restricting vocal fold motion, 3) objective assessment of airway patency, and 4) selection of a reliable management plan. More often than not, two or more BVFMI-causing factors are present; only rarely is BVFMI attributable to a single vocal fold motion-limiting cause. The clinical and endoscopic examinations should evaluate the relative contributions of vocal fold paralysis, cricoarytenoid joint fixation, infiltrative disorders, and webs and synechiae that cause restricted vocal fold motion. The flow-volume loop examination documents airflow rate and volume and the site, nature, and severjty of the obstructing lesion(s). This presentation describes the evaluation and rationale for management in BVFMI. The surgical techniques currently used to address BVFMI are compared to determine their respective merits and drawbacks, depending upon the constituent factors causing vocal fold motion limitation. KEY WORDS - arytenoidectomy, bilateral vocal fold paralysis, cordotomy, cricoarytenoid arthrodesis, infiltrative lesions of vocal folds, laryngeal web.

INTRODUCTION

vocal fold paralysis, 2) cricoarytenoid joint fixation (CAlF), 3) vocal fold infiltrative lesions (VFIL), and 4) cicatricial webs. The foregoing categories occur singularly or in combination and either may result from a primary disorder (such as bulbar palsy causing paralysis, rheumatoid arthritis causing CAJF, amyloidosis causing VFIL, and mucosal pemphigoid causing cicatricial webs) or may have an iatrogenic basis such as after surgical dissection, endotracheal intubation and endoscopic instrumentation, laser dissection, infection, bleeding, and resultant fibrosis (Table 1).

Bilateral vocal fold paralysis (BVFP), encountered most often after thyroidectomy, is occurring with diminishing frequency. It constitutes a subset of bilateral vocal fold motion impairment (BVFMI), a syndrome that is encountered with increasing frequency in the contemporary medical care setting and that arises from a broad range of circumstances ranging from blunt or endoscopic laryngeal trauma to arthritis. Bilateral vocal fold motion impairment is often the solitary residual after successful treatment of an unrelated principal medical or surgical disorder. Moreover, because the index of suspicion is not high, diagnosis of BVFMI is frequently overlooked.

TABLE 1. CATEGORIES AND CAUSES OF BILATERAL VOCAL FOLD MOTION IMPAIRMENT Bilateral vocal fold paralysis Thyroidectomy

BILATERAL VOCAL FOLD MOTION IMPAIRMENT

Parathyroidectomy Neurologic disorders Midbrain stroke Amyotrophic lateral sclerosis Cricoarytenoid joint fixation Rheumatoid arthritis Blunt neck injury Vocal fold infiltrative lesions Sarcoid Amyloid Postirradiation fibrosis Wegener's granulomatosis Lipoid granulomatosis Idiopathic fibrosis Posterior glottic web Prolonged endotracheal intubation Cicatricial pemphigoid

The principal symptoms of BVFMI are dyspnea and voice impairment. Vocal fold flaccidity results in inward vocal cord displacement on forced inspiration, airway collapse, and flow rate limitation. Outward displacement of the vocal folds on expiration causes air wastage and light-headedness. The hypotonic vocal folds appose incompletely on phonation and produce a voice with reduced loudness and limited pitch range. These symptoms can be of variable severity depending, in part, upon degree of paralysis, whether complete or partial. The resulting chronic dyspnea and easy fatigability may masquerade as chronic fatigue syndrome. There are four principal categories of BVFMI: 1)

From the Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins Medical Institutions, Baltimore, Maryland. Presented at the meeting of the American Laryngological Association, Waikoloa, Hawaii, May 4-5, 1991. REPRINTS - Haskins K. Kashima, MD, Dept of Otolaryngology-Head and Neck Surgery, The Johns Hopkins Medical Institutions, 600 N Wolfe St, Carnegie Building Room 469, Baltimore, MD 21205.

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Kashima, Bilateral Vocal Fold Motion Impairment

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Flow-volume loop spirograms in patients with bilateral vocal fold motion impairment. Pre - before cordotomy, Post - after cordotomy. A) (Case 1) 63-year-old man who had coronary artery bypass, with bilateral vocal fold paralysis and cicatricial web. B) (Case 2) 29-year-old man who sustained closed head injury, with cricoarytenoid joint fixation and cicatricial webbing. C) (Case 3) 69-year-old man who had post-supraglottic laryngectomy fibrosis, with cricoarytenoid joint fixation, vocal fold infiltrative lesions, and cicatricial webbing.

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Cricoarytenoid joint fixation immobilizes the arytenoid cartilage, through which the action of the adducting and abducting muscles is transmitted. Passive mobility of the vocal cords is preserved, and passive mobility of the aryepiglottic folds, normally stabilized by the arytenoid, may be exaggerated; hence, inspiratory stridor tends to be conspicuous and voice impairment is less severe. Infiltrative disorders such as amyloid, sarcoid, or fibrosis in the vocal folds abolish abduction and adduction in spite of intact neuromuscular function; vocal cord rigidity disallows passive displacement. Airway limitation and voice compromise tend to be severe. Cicatricial webs inhibit abduction more than adduction so that airway compromise is more severe

and voice impairment is usually minimal. Pure laryngeal paralysis abolishes voluntary abduction and/or adduction. Passive displacement of the vocal folds is greater than with CA]F, VFIL, or cicatricial webs; in paralysis of long standing, passive vocal cord excursion is exaggerated because of muscle atrophy. The above features are compounded when one or more inhibiting lesions coexist - a common occurrence. Postinflammatory reactive infiltration and cicatricial webs can be sequelae to laryngeal instrumentation and/or endotracheal intubation; such iatrogenic aftereffects compound the nature and severity of BVFMI. Irrespective of the underlying dysfunction, BVFMI presents with a near-indistinguishable clinical picture. Differentiating the four categories of BVFMI

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Kashima, Bilateral Vocal Fold Motion Impairment TABLE 2. FLOW-VOLUME LOOP SPIROGRAM VALUES BEFORE AND AFTER CORDOTOMY Expiration Patient

2

3

Date

Preoperative (2/10/88) Postoperative (4/7/88) Preoperative (2/10/87) Postoperative (11/27/90) Preoperative (10/25/88) Postoperative (3/8/89)

(Lis)

FVCI (L)

Inspiration Wmax (Lis)

WSO (Lis)

1.86

1.71

2.29

1.10

0.99

2.90

3.47

2.13

2.78

2.32

2.30

4.54

4.08

3.94

4.15

1.86

1.74

4.33

5.92

5.33

4.07

2.56

2.28

3.39

2.34

1.42

3.28

1.63

1.26

3.13

3.48

2.71

3.13

2.78

2.09

FVCE (L)

~max

VEso

(Lis)

2.29

FVCE - forced vital capacity on expiration, vrEmax - maximal expiratory flow rate, vrE50 - expiratory flow rate at 50% vital capacity, FVCI forced vital capacity on inspiration, 'VImax - maximal inspiratory flow rate, VI50 - inspiratory flow rate at 50% vital capacity.

is important in selecting the optimum treatment method (eg, whether vocal fold lateralization or nerve-muscle pedicle).

Evaluation. The objectives in clinical evaluation are recognition of BVFMI, first; assessment of presence or absence of each of the four vocal cord motion-limiting factors, second; and determination of severity of upper airway obstruction, third. The symmetric appearance of the vocal cords camouflages BVFMI, and distinguishing passive vocal cord mobility from paralysis is often difficult. Hence, examination at direct laryngoscopy should include assessment of passive mobility of the arytenoids and vocal fold tone and stiffness. Contour of the glottic aperture, particularly when tear-shaped; absence of mucosal corrugation in the interarytenoid fold; and a rounded, rather than squared, configuration at the posterior commissure are features that indicate presence of cicatricial bands or webs. Electromyographic examination is the most certain method for ascertaining neuromuscular integrity. The flow-volume loop spirogram (FVLS) identifies the site, nature, and severity of upper airway obstruction and demonstrates a characteristic pattern of variable extrathoracic obstruction in vocal cord paralysis, unilateral and bilateral. 1 Two distinct FVLS patterns are observed in upper airway obstruction due to BVFMI. When flow rate limitation occurs during both inspiration and expiration, the FVLS pattern is termed fixed; this pattern is observed in cases of VFIL (see Figure, C and Table 2). An FVLS pattern with selective inspiratory flow rate limitation and normal expiratory flow rate is termed variable extrathoracic obstruction (VEO; see Figure; A,B and Table 2). The YEO pattern is observed in BVFP, CAJF, and cicatricial webs. The FVLS examination, serially performed, objectively documents improvement or progression in respiratory flow rates and is an ideal reference standard for determining airway adequacy. A mid-vital capacity flow rate (VI50) of 1.5 Lis is the necessary threshold for moderate activity in most adults.

Management. The surgical objective in BVFMI is to expand the inspiratory glottic aperture dimension so as to enhance the inspiratory flow rate and, simultaneously, to reduce the expiratory glottic aperture to minimize excessive airflow on expiration (air wastage) and to achieve effective vocal cord apposition for phonation. To simultaneously increase and decrease glottic dimensions in a nondynamic larynx is impossible; this ideal result is achieved only by restoration of voluntary vocal cord motion. However, direct anastomosis of injured laryngeal nerves has not been successful. 2 The partial posterior cordectomy by surgical laser enlarges the posterior glottic aperture and preserves close approximation of the anterior membranous vocal cord for phonation." In lieu of cordectomy, a transverse cordotomy, immediately anterior to the vocal process, results in a wedge-shaped widening of the posterior glottis due to retraction of the divided thyroarytenoideus muscle. This triangular defect gradually assumes a rounded tearshaped opening, and glottic airway enhancement is directly proportional to the extent of vocal cord incision. Contracture of the anterior portion of the divided thyroarytenoideus increases vocal cord mass and favors a midline position for better vocal cord apposition and effective voice production. This transverse cordotomy operation offers the advantages of simplicity, minimal trauma, and a predictable degree of airway enhancement. When additional airway enlargement is necessary, a revision operation with further transverse division of the ipsilateral or contralateral vocal cord is performed. Neither cricoarytenoid joint fixation nor glottic web nor infiltrative disorders and fibrosis of the vocal cords limits effectiveness of this operation to achieve airway improvement. Dennis and Kashima, who conceived the posterior cordectomy operation, have reported that this operation can be relatively safely performed without preliminary tracheotomy. 3 Virtually all of our patients present with a tracheostomy, which we vent for several weeks postoperatively until the final

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Kashima, Bilateral Vocal Fold Motion Impairment

airway improvement becomes stabilized. In six cases reported by Dennis and Kashima in their original communication, the VIso was improved from 0.89 Lis (0.55 to 2.20) to 1.60 Lis (0.61 to 2.22) postoperatively. The preoperative maximal expiratory flow rate (VEmax) was improved from 3.32 Lis (1.20 to 5.10) to 5.22 Lis (2.09 to 8.13), and the maximal inspiratory flow rate (Vlmax) was improved from 1.32 Lis (0.80 to 2.20) to 2.35 Lis (1.48 to 2.94). On the basis of clinical observation we regard a VISO of 1.5 Lis or more to be the critical threshold for reestablishing a safe and effective airway. CASE REPORTS

Case 1. A 63-year-old man (see Figure, A) presented with persistent dyspnea and a weakened voice 3 months after a coronary artery bypass operation following which several endotracheal intubations were necessary. At operative endoscopy he had posterior glottic webs and arytenoid fixation, in addition to BVFP. Cordotomy improved his VIso from 0.99 Lis to 2.30 Lis, and an improved airway was restored. Case 2. A 29-year-old man (see Figure, B) sustained a closed head injury in a motor vehicle accident. He was unable to be decannulated after neurologic recovery. A posterior glottic web and unilateral vocal fold paralysis were documented. Cordotomy improved his VI50 from 1.74 Lis to 2.28 Lis. He was decannulated and has resumed work as a construction worker. Case 3. A 69-year-old man (see Figure, C) underwent a supraglottic laryngectomy in 1982 and received a course of postoperative irradiation therapy. He developed progressive dyspnea due to BVFMI and required a tracheotomy placement. His vocal cords were densely fibrotic. Cordotomy improved his VI50 from 1.26 Lis to 2.09 Lis and he was safely decannulated. DISCUSSION

Tracheotomy with use of a valved tracheotomy tube is a management choice of high reliability and minimal morbidity. It is particularly well suited for individuals with severe comorbidities and airway instability. Voice quality is preserved. The objective in subtotal cordectomy operations is air passage enlargement by reduction of a vocal cord mass. The final airway caliber is not precisely predictable and the voice result is imperfect. Use of the surgical laser has improved precision of vocal cord excisions, and novel techniques for reduction

of vocal cord mass with preservation of mucosa will likely be developed. The arytenoid cartilage, by virtue of its crucial relationship to the lateral and posterior cricoarytenoid, interarytenoid, and thyroarytenoid muscles, logically has long been the focus of surgical interest to achieve vocal cord lateralization. Although numerous surgical techniques have been described in minute detail, exposure of the arytenoid is difficult and usually suboptimal; the necessary muscle detachments are more readily achieved in textbook diagrams than in the operative field. Moreover, in CA]F with infiltrative or fibrotic lesions of the vocal fold, lateralization of the arytenoids and vocal cords is difficult to achieve, and in the presence of webs, the opposite vocal cord is drawn toward the repositioned arytenoid, minimizing the intended enlargement of the posterior glottic aperture. In spite of these limitations, a high proportion of successful rehabilitation in bilateral vocal fold "paralysis" has been achieved by experienced surgeons." Arytenoid removal alone is not adequate for improving the glottic airway without deliberate scar production laterally, as emphasized by Thornell, who regarded this step to be a critical part of the endoscopic arytenoidectomy operation." Arytenoidopexy is suitable in BVFP without other vocal cord-restraining factors. Neurotization of the posterior cricoarytenoid to restore vocal cord abduction is a delicate operation that requires an atraumatic surgical technique and minimal scarring. The neuromuscular pedicle operation is unlikely to succeed in cases of long-standing paralysis, but satisfactory results have been achieved in selected cases when it was performed by experienced surgeons." Neurotization would not be expected to be successful in cases with CAJF, VFIL, or cicatricial webs. CONCLUSION

Although BVFP has been and continues to be a relatively uncommon disorder, BVFMI due to paralysis, CAJF, VFIL, or cicatricial webs is encountered with increasing frequency in the current era of complex medical treatments. This presentation suggests that distinguishing these BVFMI subgroups and recognizing their unique features will lead to improved results in their management. The patient with BVFMI syndrome is plagued by a precarious airway, often in the presence of one or more serious comorbidities. In such settings, a straightforward and reliable airway restoration is of paramount importance. Transverse cordotomy by carbon dioxide laser appears ideally suited to achieve this goal.

REFERENCES 1. Kashima HK. Documentation of upper airway obstruction in unilateral vocal cord paralysis: flow-volume loop studies in 43 subjects. Laryngoscope 1984;94:923-37.

2. Tucker HM. Vocal cord paralysis - 1979: etiology and management. Laryngoscope 1980;90:585-90.

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3. Dennis DP, Kashima H. Carbon dioxide laser posterior cordectomy for treatment of bilateral vocal cord paralysis. Ann Otol Rhinol LaryngoI1989;98:930-4.

5. Thornell WC. Transoral intralaryngeal approach for arytenoidectomy in the treatment of bilateral abductor vocal cord paralysis. In: Jackson CL, ed. Diseases of the nose, throat and ear. Philadelphia, Pa: WB Saunders, 1959:647-50.

4. Woodman D, Pennington CL. Bilateral abductor paralysis. 30 years experience with arytenoidectomy. Ann Otol Rhinol LaryngoI1976;85:437-9.

6. Tucker HM. Long-term results of nerve-muscle pedicle reinnervation for laryngeal paralysis. Ann Otol Rhinal Laryngol 1989;98:674-6.

MANAGEMENT OF CRANIAL BASE DISEASES A one-day comprehensive review of contemporary management of cranial base diseasesfor neurosurgeons, otolaryngologists, ophthalmologists, radiation oncologists, and reconstructive surgeons will be held Nov 10, 1991, at the Ritz-Carlton Hotel in San Francisco, California. The course directors are Phillip H. Gutin, MD; Robert K. ]ackler, MD; and Lawrence H. Pitts, MD. For further information, contact Extended Programs in Medical Education, Room LS-I05, University of California School of Medicine, San Francisco, CA 94143-0742; (415) 476-4251.

CASSELBERRY AWARD AMERICAN LARYNGOLOGICAL ASSOCIATION The Casselberry Award has been established to encourage the advancement of the art and science of laryngology and rhinology. The award is given for outstanding theses or accomplishments in laryngology and rhinology, and consists of a suitable sum of money (up to $2,000) and a certificate from the Association. Competition for this award will be limited to those persons whose abstracts are selected for consideration for inclusion in the annual scientific program. Those wishing to compete for this award must submit their entries in the form of a complete manuscript to ALA President John M. Fredrickson, MD, Washington University Medical School, 517 South Euclid Avenue, St Louis, MO 63110, no later than November 29, 1991. The candidates and manuscripts will be reviewed by a committee; if a winner is selected, the Casselberry Award will be presented at the annual scientific meeting.

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Bilateral vocal fold motion impairment: pathophysiology and management by transverse cordotomy.

Although bilateral vocal fold paralysis (BVFP) is an uncommon disorder, bilateral vocal fold motion impairment (BVFMI) resulting from a variety of lar...
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