visual documentation and imaging of laryx.pptx

visual documentation and imaging of laryx.pptx

1. VISUAL DOCUMENTATION AND IMAGING OF LARYNX

2. INRODUCTION CT and MRI have become the procedures of choice for defining mass lesions and traumatic abnormalities and supplement the findings at laryngoscopy when additional diagnostic information is required to plan treatment . Diagnosis and extent of involvement of inflammatory lesions such as croup, epiglottitis, and retropharyngeal abscess can be confirmed with imaging . Cross-sectional imaging is extremely useful in evaluating the patient with vocal cord paralysis and laryngeal carcinoma.

3. INTRODUCTION Laryngeal endoscopy , using flexible or rigid endoscopes, is used to examine vocal fold structure and gross function . Videostroboscopy is used to examine vocal fold vibration patterns and the relationship between the body and the cover . High-speed digital imaging complements endoscopy and stroboscopy, showing details of short and aperiodic vibration as well as quantifying vibration parameters . Narrow-band imaging is a newer visualization technique that uses the tissue's light absorption characteristics to show vascular detail.

4. Normal airway Technique: Plain films remain an effective and inexpensive screening examination for acute airway obstruction . Except in rare circumstances, plain-filmexamination of the airway should include anteroposterior and lateral radiography of the pharynx and laryngotracheal air column . In cooperative patients, these films should be exposed during inspiration with the patient upright because acute respiratory obstruction may be exacerbated in the recumbent position.

5. When plain films are inconclusive, fluoroscopy and barium studies of the esophagus may be required for diagnosis. Anatomy: Lateral radiography is excellent for identifying the tongue, adenoids, tonsils, epiglottis, aryepiglottic folds, pyriform sinuses, laryngeal ventricle, and subglottic trachea. A healthy upper airway in a 20-month-old child. The following structures are well visualized : (1 ) palatine tonsils . ( 2) epiglottis, (3 ) body of the hyoid bone , ( 4 ) aryepiglottic folds , (5) laryngeal ventricl ( 6) subglottic airway, vallecula (V) , and pyriform sinus (P ) . )

6. Lateral airway radiography should be obtained as much as possible in full inspiration with the neck extended. If the study is performed during expiration or with forward flexion of the neck, the retropharyngeal soft tissue in children bulges anteriorly and may simulate a retropharyngeal Pseudoretropharyngeal mass. A, A retropharyngeal mass (M) is suggested in this child, who was examined with the neck flexed and the airway only partially distended. B, Healthy retropharyngeal soft tissue is seen when the examination is repeated during inspiration with the neck extended.

7. Clinical aspects of larygeal imaging: Inflammatory Disease of the Larynx: Epiglottitis: Epiglottitis is an inflammation of the epiglottis caused by the bacteria Haemophilus influenzae . The entire supraglottic airway may be involved, but the epiglottis and aryepiglottic folds are most extensively involved. These normally well-defined thin structures become edematous, enlarged, and unsharp, resulting in a rounded, thumblike density in place of the epiglottis. The edema often encroaches on the vallecula and rarely may extend to the posterior pharyngeal wall. In addition, the hypopharynx and pyriform sinuses are usually mildly to moderately overdistended.

8. The changes of epiglottitis are shown best on lateral radiography Epiglottitis. Marked thickening of the epiglottis (arrow) and aryepiglottic folds (arrowheads) is seen. Mild hypopharyngeal overdistention is also present On occasion, an omega epiglottis—a normal anatomic variant in children in which the epiglottis is floppy, vertically positioned, and resembles thecapital Greek letter “omega”—may be misdiagnosed as epiglottitis .

9. CROUP: Croup is an inflammation of the subglottic larynx usually caused by parainfluenza virus type 1. It typically occurs in young children. Radiographic studies are not indicated or obtained routinely in patients with croup but are useful in confusing cases, primarily to exclude other causes of stridor. The radiographic changes are the result of inflammatory edema affecting the larynx and subglottic tissue In contrast to congenital subglottic stenosis, narrowing of the subglottic portion of the trachea is not fixed and may improve on expiration.The lateral view of the neck shows the narrowing may be noted. This projection shows hypopharyngeal airway distention , but more importantly it establishes that the epiglottis and aryepiglottic folds are normal. Membranous or bacterial croup and viral croup may present with similar symptoms; however, membranous croup is characterized by diffuse inflammation of the larynx, trachea, and bronchi with adherent exudate and mucus on the surface of the upper tracheal mucosa

10. Radiographically, the frontal view is most helpful in the diagnosis. Symmetric subglottic airway narrowing or “penciling” of the airway is the major radiographic finding. Radiography shows subglottic narrowing and multiple tracheal soft tissue excrescences.These intraluminal lesions can be mistaken for foreign bodies, so clinical correlation is required for diagnosis. Membranous croup. Multiple irregular membranes (arrows) are present in the subglottic airway

11. Retropharyngeal Abscess: Retropharyngeal abscess results from suppuration of retropharyngeal lymph nodes in patients with upper respiratory tract infection or from perforation of the pharynx or upper esophagus by a foreign body. If the abscess compresses the larynx and upper trachea, symptoms of upper airway obstruction develop . Lateral soft tissue radiography of the neck will show fixed thickening of the retropharyngeal soft tissues, anterior displacement of the airway, reversal of normal cervical lordosis, and occasionally gas bubbles within the abscess.

12. Retropharyngeal abscess secondary to foreign body perforation of the esophagus. The prevertebral soft tissues are markedly swollen, and the trachea is displaced anteriorly (small arrows) . Large arrow points to a metallic foreign body. The retropharyngeal space should not exceed 7mm as measured from the most anterior aspect of C2 to the posterior pharyngeal wall. At C6, the thickness of the retropharyngeal tissues should not be greater than 14 mm in children and 22mm in adults.

13. CT and MRI superbly evaluate the retropharyngeal space . Abscess will appear hypodense on CT, hypointense on T1-weighted, and hyperintense on T2-weighted magnetic resonance (MR) images,reflecting the presence of liquefaction.Ring enhancement may be seen following administration of intravenous contrast . Retropharyngeal abscess. Enhanced CT image of the neck demonstrates a fluid collection in the left retropharyngeal space

14. Differentiation between retropharyngeal abscess and adenitis is difficult on CT because both processes cause hypodense regions within the inflammatory mass . If air bubbles or a foreign body is present within the mass, the diagnosis of a retropharyngeal abscess is more likely Thickening of the retropharyngeal soft tissues also can occur secondary to bleeding and edema from cervical spine trauma, lymphadenopathy(e.g.,lymphoma,tuberculosis),or retropharyngeal tumors (e.g., cystic hygroma,neuroblastoma,hemangioma, retropharyngeal goiter,cancer).The imaging findings should therefore be correlated with the clinical history.

15. Laryngomalacia: Laryngomalacia or congenital flaccid larynx is one of the most common causes of inspiratory stridor in the neonate and infant.Laryngoscopy shows flaccidity of the epiglottis,aryepiglottic folds, or the entire larynx, which collapses during inspiration . The primary reasons for laryngoscopy and radiography are to exclude other causes of congenital stridor (e.g., cysts, webs, tumors, stenoses). In most children, the symptoms disappear by 1 year of age.

16. Vocal Cord Paralysis: Paralysis of the vocal cord may be caused by any process involving the vagus nerve or its recurrent laryngeal branch between the jugular foramen and its entrance into the larynx. Almost 75% of patients have unilateral paralysis.Almost 90% of paralyses are caused by lesions that compress the nerve along peripherally located segments, and only 10% originate in the central nervous system or before the nerve exits the jugular foramen Specific peripheral causes include neoplasm (36%); postoperative complications, such as from parathyroid and thyroid surgery (25%); and inflammation (13%). Some cases are idiopathic.Congenital central nervous system anomalies are often associated with childhood vocal cord paralysis .

17. Imaging signs of cord paralysis include paramedian position of the cords, displaced arytenoid cartilage, ipsilateral dilation of the pyriform sinus, tilting of the thyroid cartilage, and prominent laryngeal ventricle . Although plain-film radiography, fluoroscopy, and CT can evaluate vocal cord mobility, abnormal vocal cord motion is generally diagnosed by laryngoscopy. Left true vocal cord paralysis. A, During phonation, both vocal cords are in a paramedian location (arrows). B, During inspiration, the left true vocal cord remains in a paramedian position (arrow), whereas there is abduction of the normal right true vocal cord.

18. Benign Laryngeal Masses Benign neoplasms can cause respiratory obstruction. Symptoms and imaging features depend on tumor distribution and extent. CT is the preferred screening method because of its widespread availability and superior information .

19. Subglottic hemangioma is the most common laryngeal and upper tracheal neoplasm in the newborn and infant. The lesion typically appears as a well-defined mass in the posterior or lateral portion of the subglottic airway Subglottic hemangioma. Lateral view shows a soft tissue mass (arrows) in the posterior portion of the subglottic airway. The subglottic narrowing is usually eccentric; however, circumferential narrowing suggestive of croup may also be seen. Additional hemangiomas may occur on the skin or elsewhere in the body.

20. Squamous papillomas ,the most frequent laryngeal tumors in children, have also been reported in adults. The imaging shows single or multiple intraluminal soft tissue nodules are seen in the glottis or in the tracheal air column.Because papillomas may extend to the bronchial tree or pulmonary parenchyma, chest CT is extremely important in defining the extent of disease. Laryngotracheal papillomatosis. Oblique view from a bronchogram shows multiple nodules (arrows) of varying sizes in the glottic and subglottic airway. Papillomas also may appear as well-defined discrete pulmonary nodules that eventually cavitate, forming multiple thin-walled cystic lesions.

21. Laryngocele: A laryngocele is an abnormal elongation and expansion of the saccule of the laryngeal ventricle Although laryngoceles are usually asymptomatic, large lesions may be associated with airway obstruction and vocal cord paralysis. Laryngoceles within the paraglottic space and confined by the thyroid lamina are termed internal. Lesions that pierce the thyrohyoid membrane to present in the lateral neck are termed external. Most cases are a combination of external and internal lesions and are referred to as mixed. Laryngoceles are usually visualized as sharply defined air-containing structures on imaging

22. Mixed laryngocele. Frontal view shows the large internal (I) and external (E) components of the laryngocele with compression of the supraglottic airway (arrows) Internal laryngocele. Computed tomography shows the air-filled laryngocele (L) filling the right paraglottic space and compressing the laryngeal vestibule (V). The hyoid bone (H) is also seen .

23. CT AND MRI: CT is a proven imaging technique for evaluating patients with laryngeal carcinoma. In most patients, CT shows more extensive disease than is initially appreciated by laryngoscopy. CT and MRI are excellent noninvasive methods capable of three-dimensional (3D) anatomic display of portions of the larynx that are not well examined by laryngoscopy The cross-sectional imaging provided by CT allows evaluation of the intrinsic and deep soft tissues of the larynx and the cartilaginous skeleton. MRI provides anatomic information on the neck that compares favorably with CT.

24. Advantages of MRI over CT: MRI has excellent soft tissue contrast, which is superior to CT.Multiplanar display enables coronal, transverse, and sagittal anatomic formatting, whereas CT is usually limited to the transverse plane . MRI uses no ionizing radiation and is not plagued by artifacts caused by beam hardening,dental amalgam,or poor beam penetration of the shoulders. Disadvantages of MRI over CT: It is slower than CT, and therefore motion artifacts from breathing, carotid artery pulsations , and swallowing may degrade MRI does not image cortical bone or calcifications well. MRI is contraindicated in patients with cardiac pacemakers , metallic cochlear implants, and cerebral aneurysm clips.

25. Technique: Spiral (helical) CT using multidetector technology and volumetric data sets has largely replaced conventional dynamic CT (slice-by-slice acquisition) in most medical centers . Spiral CT permits rapid scanning of large volumes of tissues during quiet respiration.Spiral images are less susceptible to patient motion than conventional CT. Volumetric spiral data permit multiplanar and 3D reconstruction.The amount of intravenous contrast may be reduced compared with dynamic CT . Iodinated contrast is administered intravenously to distinguish nonenhancing lymph nodes from enhancing vessels.

26. 3D CT is currently being used for radiotherapy planning. In MRI Sagittal, transverse, and coronal T1-weighted images best display anatomic relationships. T1-weighted and T2-weighted transverse images further define the signal characteristics of the tissues. Sections are usually 3 to 5 mm thick. Combined positron emission tomography (PET) CT is a new technique in which near simultaneously acquired PET and CT information is superimposed. This image fusion has the advantage of comparing superior sensitive functional PET data with the superior anatomic data offered by CT. PET CT is very useful in post-therapy patients for evidence of recurrent tumor, analysis of ambiguous lymph nodes and soft tissue masses, and verification of biopsy sites

27. Combined positron emission tomography/computed tomography (PET/CT) image of the neck demonstrating increased PET activity (arrowhead) superimposed on the corresponding CT image. The increased PET activity indicates hypermetabolic tumor. The CT image allows accurate anatomic localization of this tumor.

28. Normal anatomy on computed tomography showing supraglottic larynx .The two air-filled valleculae (V) separated by the median glossoepiglottic fold are seen anterior to the epiglottis (arrows). The jugular vein (j), internal carotid artery (i), external carotid artery (e), sternocleidomastoid muscle (S), and hyoid bone (H) are also seen.

29. Normal anatomy of the supraglottic larynx on magnetic resonance imaging. A , A fat-filled pre-epiglottic space (PES) is anterior to the epiglottis (arrows). The internal carotid artery (c) and internal jugular vein (j) are also seen. Fat on this sequence is higher in signal intensity than the epiglottis or muscle . B ,Five milimeters inferiorly the pyriform sinuses (P) are lateral to the aryepiglottic folds (arrowheads).

30. Normal anatomy of the false and true vocal cords on computed tomography. A , The false vocal cords (arrows ), lie at the level of the foot processes (f) of the arytenoid cartilages. The superior thyroid notch (arrowhead) is noted anteriorly between the thyroid laminae. The thyroid cartilage is incompletely calcified, which is a normal variation that should not be mistaken for cartilage destruction. The jugular vein (J) and carotid artery (C) are also seen . B , Four millimeters inferiorly, the true vocal cords (white arrow) are seen at the level of the vocal processes (arrowhead) of the arytenoid cartilages (A), located superolateral to the upper posterior border of the cricoid cartilage (Cr). Thyroid lamina join anteriorly to form the laryngeal prominence. A nterior commissure is aso seen(black arrow)

31. Normal anatomy of the true vocal cords on magnetic resonance imaging. The true cords (arrowheads) are of soft tissue intensity. The arytenoids (small arrows) and thyroid lamina (curved arrow) are seen as high signal intensity on this sequence because of fatty marrow. The superior portion of the cricoid is also shown (arrow).

32. Normal anatomy of the midsagittal plane on magnetic resonance imaging. Epiglottis (white arrow), fat-containing pre-epiglottic space (black arrow), extrinsic strap muscles (black arrowhead), arytenoid cartilages and muscles (small black arrowhead), hyoid bone (curved black arrow), and cricoid cartilage (curved white arrow) are shown. The soft palate (S), tongue (T), and spinal cord (C) are also seen.

33. Normal anatomy of the coronal plane on magnetic resonance imaging. Cricoid cartilage (large black arrowhead), thyroid cartilage (small black arrowhead), true cords (white arrowhead), and aryepiglottic folds (white arrow) are shown.

34. Laryngeal videoendoscopy Laryngeal videoendoscopy is a clinical tool that is used to examine vocal fold structure and gross function. It is used to diagnose and document voice and laryngeal disorders and plan treatment .

35. Rigid endoscopy: Advantages: Rigid scopes have the advantage of high resolution with bright, clear pictures. Contrast is excellent, there is a large selection of viewing angles image is more accurately magnified than with a flexible endoscope. The examination is simple and does not usually require topical anesthesia. Rigid endoscopes used with LVES are usually 70- or 90-degree scopes.

36. Disadvantges : The primary limitation of the rigid endoscope is that phonation is limited to sustained vowels, most commonly “ee.” Because visualization with a 70-degree rigid endoscope usually requires an extended neck and protruded tongue, the size of a glottic gap might appear exaggerated with the rigid endoscope.To counteract this problem, Rammage and colleagues suggest a lateral approach to the larynx to decrease neck extension during the examination. Alternatively, a 90-degree endoscope does not require the same amount of neck extension as the 70-degree endoscope does.

37. mobility of the arytenoids might not be accurately assessed via rigid endoscopy; often, it appears as if there is a vocal fold paresis when the perceived lack of motion is, in actuality, an artifact of the tongue protrusion and neck extension. disorders more evident in connected speech than in sustained vowels (e.g., muscle tension dysphonia and spasmodic dysphonia) are not as well documented with rigid endoscopy as they are with flexible endoscopy.

38. Technique of Rigid laryngeal videoendoscopy: The laryngeal examination with a 70-degree rigid endoscope is conducted with the patient bending slightly forward from the hips while maintaining a straight back . The neck and chin are extended, and the tongue is protruded and wrapped in gauze and holded gently during the examination. The endoscope is advanced just under the uvula or between the uvula and faucial pillars until the epiglottis is visualized . . The examiner might need to flex the wrist to tilt the endoscope tip inferiorly. The angle can be varied for differing levels of magnification and differing fields of view.

39. The patient is then instructed to sustain “ee,” which moves the epiglottis anteriorly for a better view of the vocal folds Examination with the 90-degree endoscope is similar, but the patient does not need to bend forward or extend the neck . Another difference is the angle; the tip of the 90-degree scope is positioned with minimal tilt so that the light is parallel to the surface of the vocal folds. This type of endoscope is often preferable for viewing the larynx when a wider viewing angle is desired . A longer lens or a zoom lens might be necessary for adequate visualization of vocal fold details .

40. Defogging can be done with liquid defogger, hot (not boiling) water,soap film, surgical wax, and holding the endoscope lens briefly against the patient's cheek or the side of the tongue. The examination is generally tolerated without topical anesthesia, but a small amount of benzocaine topical spray or a similar product is sometimes useful and does not appear to affect examination results

41. Flexible endoscopy: Advantages: The primary advantage of the flexible endoscope is the ability to view the larynx dynamically—that is, during natural functions such as speech and singing. Arytenoid mobility and the glottic gap can be more accurately described with flexible than with rigid endoscopy because of the neutral tongue and neck positions. Flexible endoscopy also allows the clinician to assess the nasal cavity and velopharyngeal port during the same examination.

42. Flexible endoscopy is preferred when the question is one of movement rather than structure or mucosal health. It is particularly useful for disorders such as spasmodic dysphonia and muscle tension dysphonia, in which the voice problem is more obvious during speech than in sustained vowels and where rigid endoscopy has a limited role

43. Disadvantages: The primary limitation of flexible endoscopy is that light transport and magnification of the image are inferior to those of rigid endoscopy. In addition, many patients find the flexible examination to be more invasive than the rigid examination. The flexible technique carries the risks of nosebleed, adverse reactions to the anesthetic, and vasovagal reaction.

44. Technique of Flexible Laryngeal Videoendoscopy : The flexible endoscope is typically inserted after the application of a topical anesthetic and a vasoconstrictor. It can be passed through the inferior or middle meatus of the nose.The higher path is preferred for examination of the velopharyngeal port, but the paths are equivalent for visualizing the larynx. The examiner should raise the endoscope slightly as the patient swallows to avoid triggering a cough or laryngeal closure reflex, which can occur if the endoscope touches the rising larynx during a swallow.

45. Protocol: Endoscopic parameters that require only continuous light (as opposed to the xenon light of stroboscopy) include laryngeal structure, arytenoid and vocal-fold motion, color and quantity of mucus , vascularity, supraglottic activity or compression, and deformation of vocal fold edges . Laryngeal diadochokinesis is a useful measure , and production rates of four to six syllables per second are considered normal . Examination of velopharyngeal function is indicated if nasal emission or hypernasality is heard

46. If a flexible endoscope is used, several other parameters can be assessed, including repetitions of a short “ee” followed by a quick sniff through the nose, a standard set of phrases or sentences, and conversational speech if voice quality during the endoscopic examination is not consistent with what was heard before it .

47. Protocol for Laryngeal Videoendoscopy (Continuous Light) Rigid Endoscopy Rest breathing Deep breathing Easy cough or throat clear Laryngeal diadochokinesis “ee” Laryngeal diadochokinesis “hee ” Flexible Endoscopy All components of rigid exam “ee” followed by a quick sniff (x3 ) Whistling Sentences and/or conversation as needed Observation of velopharyngeal function during sustained sounds such as “ee” and “s” Observation of velopharyngeal function during sentences loaded with nasal-oral contrasts

48. Laryngeal structure: The valleculae, pyriform sinuses, epiglottis, aryepiglottic folds, ventricular folds, and posterior glottic rim should be examined. Lowered pitch during sustained “ee” widens the angle,allowing better visualization of the valleculae. Abnormalities and asymmetries of laryngeal structure are noted. An omega-shaped epiglottis is a common variant in men, but it is rare in women. Signs of laryngeal irritation or possible laryngopharyngeal reflux are noted; these primarily include edema, erythema, surface irregularities, and lesions of the posterior larynx .

49. Arytenoid and vocal fold motion: Movement and position of the arytenoids tell us about the integrity of the cricoarytenoid joint and the recurrent laryngeal nerve. Arytenoids are typically described as mobile or immobile, symmetric or asymmetric, and upright or rotated. Immobility is further described by position: median, paramedian, intermediate, or lateral . Motion of the arytenoid should be described separately from movement of the posterior third of the vocal fold because sometimes the arytenoid is mobile when the vocal fold is fixed . Mobility is rated when patients phonate then breathe, and during laryngeal diadochokinesis, cough, whistling, and sniff.

50. Mucus: Thickened mucus often adheres to the vocal fold edges or superior surface. The presence of thick mucus generally relates to a lack of hydration or to chronic irritation due to mechanical trauma, smoking, or laryngopharyngeal reflux . Mucus pooling in the pyriform sinuses can indicate poor laryngeal sensation, weak lateral pharyngeal walls, or inefficient swallow . Thickened mucus adhering to the vocal folds can be misinterpret as a lesion or mask an abnormality. So,to allow differentiation of mucus from underlying structures or lesions, patients should be instructed to try to clear the mucus by swallowing or gentle cough.

51. Vascularity: The vocal folds are generally pearly white.A blush throughout the tissue is considered erythema or hyperemia. If capillaries are visible, they are generally aligned parallel with the free edge ; horizontal vascularity is cause for concern . Abnormally dilated and tortuous vessels, called capillary ectasias or microvarices , might represent areas of stiffness or risk for hemorrhage. Hemorrhage occurs when enough blood cells have escaped from a vessel to lend a diffuse coloring to the vocal fold. Post-hemorrhage vocal folds often appear yellowbrown,similar to healing bruises in other areas.

52. Assessment Using Stroboscopy A stroboscope is defined as “an instrument for determining the speed of cyclic motion (as rotation or vibration) that causes the motion to appear slowed or stopped .” Videostroboscopy is not slow-motion photography; it is an illusion of slow motion. The illusion is possible because images linger on the retina for 0.2 second, and only five distinct images can be viewed per second. If more than five per second are presented, the viewer perceives the images as connected and sees the result as a smooth motion; this phenomenon is referred to as Talbot's law. Videostroboscopy is used to assess vocal fold vibration patterns, mucosal pliability, the underlying layered structure of the vocal folds, and the undersurface of the vocal fold edges. It isparticularly valuable for assessing stiffness, scar, or submucosal injury; detecting small vocal fold lesions; estimating the depth of invasion of a tumor; identifying asymmetric mass or tension ; or determining the resumption of phonation after phonosurgery.

53. Stroboscopic parameters include closure pattern, phase closure, amplitude of vibration, mucosal wave, adynamic segments, vertical closure level, symmetry, and regularity. Of these,closure and mucosal wave are often considered key indicators of function . The patient should produce a variety of pitches during the examination. Bilateral and symmetric lengthening of the folds during ascending pitch glides confirms that gross cricothyroid muscle function is intact . High-pitch phonation is useful for highlighting midmembranous edema and stiff or scarred segments along the edge.

54. Protocol for Laryngeal Videostroboscopy (Xenon Light) Rigid Endoscope Sustained “ee” at patient's most comfortable pitch and loudness (MCPL) (several) “ee” on inhalation Glide midrange to high, sustaining the high note Glide midrange to low, sustaining the low note Quiet “ee” Loud “ee” Sustained “ee” at MCPL using locked mode Trial therapy or laryngeal manipulation as needed Flexible Endoscope All components of rigid exam Consensus Auditory Perceptual Evaluation for Voice (CAPE-V ) sentences: “The blue spot is on the key again.” “How hard did he hit him?” “We were away a year ago.” “We eat eggs every Easter.” “My mama makes lemon muffins.” “Peter will keep at the peak.” Singing tasks as necessary Conversation as necessary Humming or other trial therapy tasks as needed

55. Closure pattern indicates how well the vocal folds come together at midline during the closed phase of the vibratory cycle. Glottal closure and gap patterns. A , Complete closure; B , posterior glottic gap; C, anterior glottic gap ; D , spindle-shaped gap; E , hourglass-shaped gap.

56. Although “ closure pattern ” describes the extent of closure, “ phase closure ” describes the duration of closure. During vibration at MCPL, the glottis is typically open (opening, fully open, or closing ) for approximately two thirds of one vibratory cycle and maximally closed for the remaining third . Mucosal wave is the vertical upheaval of the cover over the body. Increased mucosal wave (i.e., it moves farther across the fold) is observed when mucosa is abnormally pliable, such as in polypoid degeneration or when there is increased subglottal air pressure. decrease or absence of mucosal wave is seen with some pathological conditions like scarring, or sulcus vocalis. Incomplete glottic closure resulting from aging, atrophy, or motion impairment can also lead to decrease or absence of mucosal wave

57. A, Complete glottic closure. B, Maximum amplitude of vibration/excursion Amplitude of vibration refers to the fold's horizontal excursion from midline. Normal is defined as approximately one third of the width of the fold. Decreased amplitude is common in lesions such as firm polyps, cysts, papilloma, carcinoma, Reinke's edema, scarring, and hyperfunction. Increased amplitude may be a sign of decreased tonicity, as observed in vocal-fold paresis or atrophy.

58. Adynamic segments refers to nonvibrating areas of the vocal fold (i.e., areas that have no mucosal wave and poor amplitude of vibration ). Symmetry is a timing parameter. It refers to the extent to which the vocal folds appear as mirror images of each other during vibration. The vocal folds should depart from midline at the same time and arrive back at midline at the same time . Regularity (or periodicity) describes the degree to which one phonatory cycle is similar in both amplitude and time to the next phonatory cycle . Vibratory regularity is rated just like symmetry, either by describing the percentage of time that the vibration was regular or irregular or by describing occurrences of irregularity . Aperiodic vibration gives rise to acoustic noise, which can be perceived as roughness or hoarseness.

59. Vertical Closure Level: Whether the vocal folds meet on the same plane is typically rated as on-plane or off-plane. Closure is off-plane typically because of either neuromuscular differences between the folds (paralysis or paresis) or laryngeal trauma or surgery .

60. Narrow-Band Imaging Narrow-band imaging (NBI) is a new endoscopic imaging technique that employs the absorption characteristics of light for the detailed analysis of mucosal and vascular structures . NBI takes advantage of the differential absorption characteristics of tissues. Blue light with its shorter wavelength is better absorbed by hemoglobin . NBI shows promise for improving the yield of biopsies by directing the examiner to the more “ suspicious” areas , a type of optical biopsy. It is currently available for gastroscopes including transnasal esophagoscopes and flexible laryngoscopes. Clinicians are beginning to explore the utility of NBI in laryngeal and hypopharyngeal lesions

61. True vocal-fold scar at the anterior commissure. A , White light ; B, narrow-band imaging.