Videolaryngoscopy and Stroboscopy

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Videolaryngoscopy and Stroboscopy

Laryngology, Voice and Swallowing
Author Credentials 

Peak Woo, MD
Department of Otolaryngology
Icahn School of Medicine at Mount Sinai
300 Central Park West. 1-H
New York, NY 10024
Email: peakwoo@peakwoo.com
 

Module Summary

Fiber optic laryngoscopy and rigid per-oral endoscopy are methods for imaging the upper aero-digestive tract. Imaging with video is now standardized with defined protocols for both anatomical and pathological changes to the vocal tract as well as observation of airway physiology and vibratory function. The imaging modalities today include the use of stroboscopy light, narrow band imaging, and high speed camera. Using stroboscopy, the clinician can observe vocal vibratory function in patients presenting with dysphonia that otherwise could not be diagnosed. By systematic observation and interpretation of the vocal fold vibration patterns, the clinician can categorize voice disturbances into the broad category of mass, tension, or stiffness patterns. Treatment of voice disorders based on stroboscopy findings is more refined. Flexible laryngoscopy continues to evolve with better “chip-tip” technology and improved resolution. Its use in documentation, lesion detection and diagnosis of airway and swallow dysfunction will continue. It has an invaluable added benefit in better evaluation and management of patients with vocal fold motion abnormalities, laryngeal spasm and swallow dysfunction.

Module Learning Objectives 
  1. Describe the laryngeal anatomy and laryngeal function that is unique to examination by the use of video flexible laryngoscopy, rigid indirect laryngoscopy and video stroboscopy.
  2. Select between the different laryngoscopy techniques based on the patient’s symptoms and physical findings.
  3. Interpret a videostroboscopy examination based on a systematic rating form for videostroboscopy.
  4. Analyze a fiber optic laryngoscopy and be able to systematically tabulate the relevant features that go into a complete report of fiber optic laryngoscopy.
  5. Integrate the findings from both the flexible laryngoscopy and videostroboscopy to synthesize a differential diagnosis list in patients with voice disorders.
  6. Recommend treatment approaches based on the findings from fiber optic laryngoscopy and videostroboscopy.
  7. Summarize the indications and findings from a fiber optic laryngoscopy and videostroboscopy to justify the performance of these procedures.

Embryology

Learning Objectives 
  1. Define the development of the larynx in the life span changes.
  2. Know the development of the lamina propria and the life-span changes from infancy to senesce.
References 
  1. Sato K, Hirano M, Nakashima T. Fine structure of the human newborn and infant vocal fold mucosae. Ann Otol Rhinol Laryngol. 2001;110:417-424.

Anatomy

Learning Objectives 
  1. Understand the layered micro-anatomy of the vocal fold cover and how it contributes to vocal fold vibration and the production of voice.
    1. Body cover theory of vocal fold oscillation
    2. Vocal fold histology and the basement layer
    3. Superficial layer of the lamina propria
    4. Intermediate layer of the lamina propria
    5. Deep layer of the lamina propria
    6. Vocalis
  2. Know the anatomy of the oral pharynx, base of tongue, hypopharynx, supraglottic larynx, glottis larynx, subglottic larynx, and cervical trachea that can be evaluated by fiberoptic laryngoscopy.
  3. Describe the anatomical and physiological changes in production of voice
  4. Vocal fold vibration and phonatory physiology
    1. The glottal cycle is described by the following in modal phonation:
      1. Quasi-periodic oscillation
      2. Opening and closing phase and closed phase
      3. Opening phase = closing phase
      4. Open phase is equal in duration to closed phase
      5. Symmetry in motion between the two vocal folds.
  5. Normal phonation and vocal fold vibration, dynamic changes in the glottal cycle
    1. Modal voice
    2. Falsetto voice
    3. Vocal fry
    4. Gender differences
    5. Registration transition changes
    6. Age differences
      1. Infant
      2. Adult
      3. Aging changes
  6. Loudness modulation effects on the glottal cycle
  7. Frequency modulation effects on the glottal cycle
References 

 

  1. Hirano M. Clinical examination of voice. New York: Springer-Verlag; 1981.
  2. Campos Banales ME, Perez Pinero B, Rivero J, Ruiz Casal E, Lopez Aguado D. Histological structure of the vocal fold in the human larynx. Acta Otolaryngol. 1995;115:701-704.
  3. Woo P. Stroboscopy. San Diego, Ca: Plural Publishing; 2010.

Pathogenesis

Learning Objectives 
  1. Understand the pathophysiology of voice and swallow dysfunction that originating in laryngeal and pharyngeal dysfunction that is to be evaluated by fiberoptic laryngoscopy
  2. Describe the pathology of disturbed vocal vibratory function that result in impaired vocal function that can only be evaluated by stroboscopy or high speed video of vocal vibratory function.
  3. Abnormal vocal fold vibration
    1. Mass abnormality
    2. Tension abnormality
    3. Stiffness and abnormality
    4. Problems of glottal closure and competence
References 
  1. Butler SG, Stuart A, Kemp S. Flexible endoscopic evaluation of swallowing in healthy young and older adults. Ann Otol Rhinol Laryngol. 2009;118:99-106.
  2. Woo P, Casper J, Colton R, Brewer D. Diagnosis and treatment of persistent dysphonia after laryngeal surgery: a retrospective analysis of 62 patients. Laryngoscope. 1994;104:1084-1091.

Basic Science

Learning Objectives 
  1. Review and describe the myoelastic aerodynamic theory of vocal fold vibration
  2. Know the differences between fiber optic laryngoscopy systems and how it impacts observation of lesions of the larynx
  3. List the advantages and limitations of rigid versus flexible laryngoscopy evaluation of the larynx
  4. Recognized the added value of narrow band imaging in diagnosis of vocal fold lesions. (Level IV)
  5. Principles of videostroboscopy (LEVEL 1)
    1. The principle of stroboscopy for slowing visualization of vocal fold motion is based on Talbot’s law. The successive presentation of images illuminated by a brief intense light is retained on the retina for a certain number of milliseconds.
    2. Pulses of microseconds of light that is synchronized to periodic vibration can freeze the motion and if it is synchronized to different portion of the vibration cycle will show pseudo-motion. In patients with periodic vocal fold oscillation, a stroboscope examination can show the vibratory characteristics of the glottal cycle. (Level III)
    3. The stroboscopy image is a montage of many hundreds of glottal cycles. If the recorded segment is periodic then the stroboscopy examination approximates the true motion being studied by stroboscopic light.
    4. Use of stroboscopic light has been used for more than 100 years in the study of the glottal cycle and pathology related to vocal fold vibration (Level II)
    5. Added role of emerging technology such as high speed video.
References 
  1. van den Berg JW. Myoelastic-aerodynamic theory of voice production. J Speech Hear Res. 1958;1:227-244.
  2. Plaat BE, van der Laan BF, Wedman J, Halmos GB, Dikkers FG. Distal chip versus fiberoptic laryngoscopy using endoscopic sheaths: diagnostic accuracy and image quality. Eur Arch Otorhinolaryngol. 2014;271:2227-2232.
  3. Zwakenberg MA, Dikkers FG, Wedman J, Halmos GB, van der Laan BF, Plaat BE. Narrow band imaging improves observer reliability in evaluation of upper aerodigestive tract lesions. Laryngoscope. 2016;126:2276-2281.
  4. Benjamin B. Technique of laryngoscopy. Int J Pediatr Otorhinolaryngol. 1987;13:299-313.
  5. Hirano M, Bless D. Videostroboscopic Examination of the Larynx. San Diego, CA.; 1993. San Diego, CA: Singular Publishing Group Inc, 1993.
  6. Patel R, Dailey S, Bless D. Comparison of high-speed digital imaging with stroboscopy for laryngeal imaging of glottal disorders. Ann Otol Rhinol Laryngol. 2008;117:413-424.

Incidence

Learning Objectives 
  1. Know the incidence of dysphonia and populations at risk for dysphonia in the pediatric, adult and geriatric population.(Level 3)
  2. Appreciate high risk groups of professional voice users at risk for dysphonia including: singers, actors’ teachers, and call center workers. (Level 3)
References 
  1. Schwartz SR, Cohen SM, Dailey SH, et al. Clinical practice guideline: hoarseness (dysphonia). Otolaryngol Head Neck Surg. 2009;141:S1-S31.

Patient Evaluation

Learning Objectives 

Applications of Videostroboscopy and flexible laryngoscopy

  1. Documentation
  2. Clinical care in laryngological and voice care
  3. Flexible laryngoscopy is indicated in:
    1. Patients who cannot be examined with the indirect method
    2. Patients with resonance and articulation disorders
    3. Breathy and strained voice quality
  4. Stroboscopy is indicated in
    1. Rough and hoarse patients with normal indirect laryngeal examination
    2. As part of exploration of the voice production in patients with dysphonia
    3. Persistent dysphonia
  5. Clinical examination of the larynx using stroboscopy
    1. Rigid endoscopy and videostroboscopy
      1. Tasks and tokens
      2. Modal voice
      3. High pitch phonation
      4. Low pitch phonation
      5. Loud phonation
      6. Pitch and loudness variation
      7. Male versus female examination
      8. The basic examination in videostroboscopy
    2. Avoiding the pitfalls of stroboscopy
      1. Artifacts due to pitch tracking errors
    3. Common mistakes due to aperiodicity
  6. Fiber optic laryngoscopy: Tasks an tokens in the fiberscope examination
    1. Abduction and adduction
    2. Observer for vocal fold motion asymmetry
    3. Observation of anatomical sub sites for lesions
    4. Vegetative and phonation tasks to be performed
    5. “eee-sniff” gesture
    6. Diadokinesis
    7. Cough
    8. Respiration
    9. Rapid articulation of plosives and consonants
    10. Articulatory precision
    11. Singing and speech tasks relevant to chief complaint.
References 
  1. Russell KA, Brook CD, Platt MP, Grillone GA, Aliphas A, Noordzij JP. The Benefits and Limitations of Targeted Training in Flexible Transnasal Laryngoscopy Diagnosis. JAMA otolaryngology-- head & neck surgery. 2017.
  2. Woo P, Parasher AK, Isseroff T, Richards A, Sivak M. Analysis of laryngoscopic features in patients with unilateral vocal fold paresis. Laryngoscope. 2016 Aug;126(8):1831-6.
  3. Fleischer S, Schade G, Hess MM. Office-based laryngoscopic observations of recurrent laryngeal nerve paresis and paralysis. Ann Otol Rhinol Laryngol. 2005;114:488-493.

Measurement of Functional Status

Learning Objectives 
  1. Interpretation of videostroboscopy at standard fundamental frequency and loudness for gender tested
    1. Configuration
    2. Symmetry
    3. Regularity (periodicity)
    4. Glottic closure
    5. Amplitude of vibration
    6. Phase of vibration
    7. Mucosal wave propagation
    8. Non-vibration portion
    9. Edge
    10. In or out of phase vibration
  2. Interpretation of flexible laryngoscopy
    1. Anatomy and observation of the upper aerodigestive tract
      1. oropharynx,
      2. hypopharynx,
      3. larynx (supraglottis, glottis, subglottis)
      4. Cervical trachea
    2. Pharyngeal movement and vocal fold movement
      1. Velopharyngeal closure
      2. Abduction and adduction angles
      3. Diadokinesis
      4. Vocal fold motion asymmetry
      5. Phonation and laryngeal motion during voice, speech and swallow
      6. Paradoxical vocal fold motion disturbance
      7. Pharyngeal squeeze
    3. Swallow and deglutition
      1. Fiberoptic endoscopy of swallow function
    4. Cough, Valsalva, laryngospasm and respiration motion assessment
References 
  1. Merati AL. In-office evaluation of swallowing: FEES, pharyngeal squeeze maneuver, and FEESST. Otolaryngol Clin North Am. 2013;46:31-39.
  2. Butler SG, Stuart A, Kemp S. Flexible endoscopic evaluation of swallowing in healthy young and older adults. Ann Otol Rhinol Laryngol. 2009;118:99-106.
  3. Fleischer S, Schade G, Hess MM. Office-based laryngoscopic observations of recurrent laryngeal nerve paresis and paralysis. Ann Otol Rhinol Laryngol. 2005;114:488-493.

Imaging

Learning Objectives 

Videolaryngoscopy is used to examine and record the structure and function of the upper aero digestive tract during respiratory and deglutition function. Videostroboscopy is used to examine and record the vibratory characteristics of the vocal fold and its mucosal margin during phonation.

  1. Choice of examination and equipment
    1. Children under 5 years are best examined by fiberoptic technique
    2. Operative laryngoscopy should be considered in patients that have suspected lesion but cannot be examined by office video laryngoscopy approaches.
    3. Rigid endoscopes have the advantage of better resolution
    4. Narrow band imaging and high speed video are emerging technologies that can be considered in selected voice and lesion differential diagnosis
  2. Flexible laryngoscopy with or without video should be considered with the highest resolution possible
    1. Use of chip tip technology with or without stroboscopy is now the standard
    2. The standard definition on video format is High definition with higher resolutions in development
  3. Stroboscopy indications
    1. Small mass lesions of the vocal folds (cysts, subglottic polyps)
    2. Focal stiffness or scarring (sulcus)
    3. Mucosal hygiene and detection of subtle edema (puffy cords secondary to corditis)
    4. Micro-varix and angioma
    5. Vibratory abnormalities due to microscopic changes in the vocal cover
  4. Examination begins with evaluation of the auditory characteristics such as pitch range, volume, resonance, grade, roughness, strain, breathiness and asthenia.
  5. Auscultation findings of stridor and findings on palpation of laryngeal movement and pain can guide examiner as to site and technique of testing.
  6. Objective measures are largely still investigational
References 
  1. Rosen CA. Stroboscopy as a research instrument: development of a perceptual evaluation tool. Laryngoscope. 2005;115:423-428.
  2. Woo P. Objective measures of laryngeal imaging: what have we learned since Dr. Paul Moore. J Voice. 2014;28:69-81.

Pathology

Learning Objectives 
  1. Describe the major pathological findings on stroboscopy in patients with unilateral vocal fold pathology that results in stiffness of the vocal fold
    1. Stroboscopy
      1. asymmetric amplitude
      2. decreased amplitude
      3. short closed phase
      4. failure of mucosal wave propagation
      5. non-vibrating segment
  2. Describe the major laryngoscopy findings on flexible laryngoscopy that is consistent with vocal fold paresis and vocal fold dysfunction
    1. Paradoxical motion with vocal fold inward motion during deep inspiration
    2. Vocal fold paresis can result in:
      1. Kinetic differences with reduced vocal fold movement
      2. Configuration differences with vocal fold bowing and level differences
      3. Differences in degree of abduction and closure to the midline
  3. Know the major types of vascular patterns in epithelial diseases that can be highlighted using Narrow Band Imaging
References 
  1. Olthoff A, Woywod C, Kruse E. Stroboscopy versus high-speed glottography: a comparative study. Laryngoscope. 2007;117:1123-1126.
  2. Brook CD, Platt MP, Russell K, Grillone GA, Aliphas A, Noordzij JP. Time to competency, reliability of flexible transnasal laryngoscopy by training level: a pilot study. Otolaryngol Head Neck Surg. 2015;152:843-850.
  3. Shoffel-Havakuk H, Lahav Y, Meidan Bet al. Does narrow band imaging improve preoperative detection of glottic malignancy? A matched comparison study. Laryngoscope. 2017 Apr;127(4):894-899.

Case Studies

  1. A 36-year-old man with prolonged history of voice loss after vocal fold polyp surgery. A CO2 laser was used to remove a right sided vocal fold polyp in 2013. This was followed by a second procedure several months later when he complained of a worse voice. This was done on the left. He is using his voice in sales. He describes excessive vocal strain and vocal fatigue. Despite extensive voice therapy with a speech pathology approach, he is not able to function in his current job. Prior laryngoscopy has not revealed any new lesions on either vocal fold. He was told this is a functional loss of the voice due to his vocal strain. On physical examination, the quality of the voice is severe in roughness and moderate in breathiness. There is severe strain with neck bulging on phonation. The phonation time is reduced to only 4 seconds with a marked reduction in dynamic range. Mirror examination shows good vocal fold motion without evidence of inflammation in the hypopharynx and the posterior larynx. What should be in the differential diagnosis in this man other than muscle tension dysphonia? What would you expect to see on videostroboscopy? Would you use a rigid endoscope or a flexible endoscope for the initial examination? What would you find on videostroboscopy that would support your suspicion of: unilateral vocal fold scarring, bilateral vocal fold scarring, excessive loss of vocal fold tissue with glottis incompetence? What further testing if any is necessary? How would you elect to treat this patient based on the stroboscopy findings?
  2. A 44-year-old female teacher presents with difficulty in ability to teach after removal of a polyp. The polyp surgery was done 2 months ago for voice disturbance. The surgery improved the voice from a rough voice to a clearer voice but the vocal fatigue and loss of volume is disturbing. She gives a history of having a total thyroidectomy 5 years ago for thyroid cancer. This was followed by radioactive iodine. Most recent laboratory testing shows normal thyroglobulin levels, normal ultrasound of the thyroid and a normal chest x-ray. On physical examination, she is slightly breathy with mild dysphonia. An office laryngoscopy by mirror examination shows some vocal fold movement from both sides but movement symmetry was not certain. What further testing is necessary? How would you systematically test this patient on flexible laryngoscopy for the suspected diagnosis of vocal fold paresis? What is in the differential diagnosis for this patient’s vocal complaint? How would you elect to further work up this patient? What treatment could be considered based on an in-depth fiberscope examination of vocal fold motion?

Complications

Learning Objectives 
  1. Understand the errors that are related to delay in diagnosis due to untimely referral for stroboscopy and fiberoptic laryngoscopy.
  2. Defend the use of state of the art technology in fiberoptic imaging of the upper airway.
  3. Know the reliability in use of NBI in defining lesions of uncertain behavior.
References 
  1. Sulica L. Hoarseness misattributed to reflux: sources and patterns of error. Ann Otol Rhinol Laryngol. 2014;123:442-445.
  2. Woo P, Colton RH, Casper J, Brewer DW. Diagnostic value of stroboscopy examination in hoarse patient's. J Voice. 1991;5:231-238.
  3. Chang C, Lin WN, Hsin LJet al. Reliability of office-based narrow-band imaging-guided flexible laryngoscopic tissue samplings. Laryngoscope. 2016;126:2764-2769.
  4. Paul BC, Rafii B, Achlatis S, Amin MR, Branski RC. Morbidity and patient perception of flexible laryngoscopy. Ann Otol Rhinol Laryngol. 2012;121:708-713.

Review

Review Questions 
  1. What is the most common indication for referral for videostroboscopy?
  2. What are the most common stroboscopic features in a patient with unilateral vocal fold cyst?
  3. What diagnostic tests are indicated in a young athlete female with exertion stridor brought on with exercise?
  4. Which voice characteristics would benefit from stroboscopy vs. fiber optic laryngoscopy?
  5. How would you go about doing the standard battery of voice tokens in a simple examination of a male patient with a slightly rough voice quality? What four tokens would you ask for? What frequency? What loudness?
References 
  1. Paul BC, Branski RC, Amin MR. Diagnosis and management of new-onset hoarseness: a survey of the American Broncho-Esophagological Association. Ann Otol Rhinol Laryngol 2012; 121:629-634.
  2. Sadoughi B, Fried MP, Sulica L, Blitzer A. Hoarseness evaluation: a transatlantic survey of laryngeal experts. Laryngoscope 2014; 124:221-226.
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