Laryngoscopy (Flexible, Direct)

Laryngoscopy is the direct view of the larynx (voice box) and the surrounding throat. It is used to examine the vocal folds, the supraglottis, the hypopharynx, and the airway.

Flexible laryngoscopy is done in clinic with a thin fibreoptic or chip-on-tip scope passed through the nose, in an awake patient.

Direct laryngoscopy uses a rigid laryngoscope or operating microscope, usually under general anaesthesia in an operating theatre. It gives a clearer and more detailed view and allows biopsy and surgery.

For flexible laryngoscopy, the nose is treated with a decongestant and local anaesthetic spray. The scope passes along the floor of the nose, through the nasopharynx, and down to the oropharynx and larynx.

The patient is asked to say "ee" (to bring the vocal folds together and raise the larynx), to breathe quietly, to sniff, to cough, and to swallow. This shows movement of the vocal folds, the pharyngeal wall, and the airway. The test takes 2 to 5 minutes.

Direct laryngoscopy takes 15 to 45 minutes and allows microsurgery, biopsy, removal of foreign bodies, and treatment of lesions.

Voice problems affect up to 1 in 3 adults over a lifetime. Hoarseness lasting more than 3 weeks warrants laryngoscopy in everyone, and especially in smokers and in people over 40 years, because laryngeal cancer is the most serious cause. Laryngeal cancer accounts for about 1 to 2% of cancers worldwide, and smoking and alcohol are the main risks.

Indications.

• Hoarseness or voice change for more than 3 weeks, or any voice change in smokers.
• Persistent sore throat, throat pain, or a sense of a lump in the throat.
• Difficulty swallowing, pain on swallowing, or food sticking, and coughing or choking with eating.
• Stridor, noisy breathing, and airway obstruction.
• Chronic cough, throat clearing, and suspected reflux affecting the larynx.
• Neck mass, referred ear pain, or blood-stained sputum, to look for a head and neck cancer.
• Vocal fold paralysis, after neck, thyroid, or chest surgery or intubation.
• Assessment of the airway, and of the larynx after intubation or caustic injury.
• Direct laryngoscopy: biopsy of suspicious lesions, removal of foreign bodies, microsurgery of vocal folds (polyps, cysts, nodules), staging of laryngeal and hypopharyngeal cancer, and airway management. Not a substitute for imaging of the neck and chest when the cause of vocal fold paralysis or cancer extent is needed.

Contraindications and precautions.

• Flexible laryngoscopy has few contraindications. Caution in epiglottitis or severe upper airway obstruction (stridor with distress), where examination can precipitate complete obstruction, and is done only where the airway can be secured.
• Allergy to local anaesthetic or decongestant, and uncontrolled hypertension or heart disease with decongestants.
• Bleeding disorders and anticoagulation: caution with biopsy. Gagging, vasovagal faint, and nosebleeds are possible.
• Direct laryngoscopy needs general anaesthesia: fitness for anaesthesia, fasting, assessment of the neck (cervical spine disease, limited mouth opening, a short neck, large tongue), and loose teeth are checked.
• Suspected unstable cervical spine, severe trismus, or a mass that blocks the airway: an experienced airway team and a plan for a surgical airway.
• Infection control: scopes are decontaminated, or single-use scopes are used.
• Patients should not eat or drink for about an hour after topical anaesthesia of the throat until the numbness wears off.

Preparation and technique.

For flexible laryngoscopy, the patient sits upright, with the head slightly forward. A nasal decongestant and local anaesthetic spray is applied, and the scope is passed along the nasal floor.

At the oropharynx, the patient is asked to breathe quietly, say "ee" and hum, count, and cough, while the larynx is viewed, and the base of the tongue, vallecula, epiglottis, pyriform sinuses, arytenoids, false and true vocal folds, and subglottis are inspected. Movement, colour, edge, and closure of the vocal folds are noted, and a recording is kept.

For direct laryngoscopy, the patient is anaesthetised and intubated or ventilated by a jet technique, the laryngoscope is placed to bring the larynx into view, and the microscope or telescopes are used to inspect, photograph, palpate, biopsy, and treat lesions. The patient is monitored until awake and gag reflex returns.

Normal appearances.

The epiglottis is thin and curved. The true vocal folds are pearly white, smooth, and straight-edged, and they move symmetrically, opening widely on breathing in and closing completely on phonation. The false folds, arytenoids, and pyriform sinuses are smooth and pink, and there is no pooling of saliva. The airway at the glottis is wide, and the subglottis is clear.

Interpretation.

• Vocal fold nodules: small, symmetrical swellings at the junction of the front and middle thirds, in voice abuse.
• Vocal fold polyp or cyst: unilateral swelling, with a possible reactive swelling on the other side.
• Reinke oedema: diffuse, swollen, watery vocal folds, in smokers.
• Laryngitis: red, swollen vocal folds, in infection or reflux, with thick secretions. Reflux signs include posterior erythema and oedema, but are non-specific.
• Vocal fold paralysis: a fixed fold in a median or paramedian position, with a bowed fold, breathy voice, and pooling of saliva. A bilateral paralysis gives a narrowed airway.
• Leukoplakia or erythroplakia: white or red patches that may be premalignant.
• Laryngeal cancer: an irregular, ulcerated, or exophytic mass, with fixed fold, and possible spread to the supraglottis or subglottis.
• Papillomas: warty growths, in children and adults.
• Foreign body or oedema in acute airway blockage, with a swollen epiglottis in epiglottitis.
• Granuloma at the back of the larynx: after intubation or reflux.
• Subglottic stenosis: a narrowed airway under the vocal folds.
• Hypopharyngeal pooling, tumour, or pouch: dysphagia assessment.

Critical values and findings needing immediate action.

• Stridor with a swollen epiglottis or severe airway narrowing: an airway emergency, with early involvement of anaesthesia and a surgical team.
• Suspected laryngeal or hypopharyngeal cancer (mass, ulcer, fixed fold): urgent biopsy and staging imaging within days.
• Bilateral vocal fold paralysis with stridor: urgent airway assessment.
• Unilateral vocal fold paralysis without an obvious cause: imaging from skull base to chest, since the course of the recurrent laryngeal nerve can be involved by tumour.
• Foreign body in the airway: urgent removal under direct laryngoscopy.
• Burns or caustic injury to the larynx: urgent airway assessment.

Limitations and artefacts.

• Flexible laryngoscopy gives a good view of function, but the picture may be less sharp than with rigid telescopes, and small lesions, the front of the larynx, and the subglottis may be missed.
• A strong gag reflex, a narrow nasal passage, secretions, and poor cooperation limit the view. Local anaesthesia may change the voice and the movement of the folds.
• Stiffness and movement are best judged with stroboscopy, since the vibration of the folds cannot be seen in normal light.
• The appearance of reflux laryngitis is non-specific, and the finding of redness is common in healthy people.
• Biopsy is not done at flexible laryngoscopy except for superficial lesions, and a normal-looking larynx does not exclude disease deeper in the larynx, hypopharynx, or oesophagus.
• Direct laryngoscopy has anaesthetic risks, and can cause dental damage, sore throat, bleeding, airway swelling, and rarely perforation or injury to nerves.
• Complications of flexible laryngoscopy are uncommon, and include nosebleed, gagging, vasovagal episodes, and laryngospasm.

Special groups.

• Children: flexible laryngoscopy is done with a thin scope, and is used for stridor, hoarseness, and suspected laryngomalacia (the commonest cause of infant stridor). Rigid endoscopy under anaesthesia is used for airway lesions, foreign bodies, and papillomas.
• Smokers and heavy drinkers: a low threshold for examination and biopsy.
• Singers and voice professionals: stroboscopy and voice assessment.
• Patients after thyroid, neck, or cardiac surgery, and after intubation: voice change is checked early.
• Patients on anticoagulants: biopsies are planned with care.
• Regions: laryngeal and hypopharyngeal cancers are often found at a late stage, and tobacco, alcohol, and betel nut are common risks. Laryngeal tuberculosis, papillomatosis, and diphtheria and epiglottitis in unvaccinated children are important causes. Indirect (mirror) laryngoscopy is a low-cost alternative where flexible scopes are unavailable.

Follow-up tests.

• Videostroboscopy for vocal fold vibration.
• Biopsy and histology of suspicious lesions.
• CT or MRI of the neck and chest for tumour staging or vocal fold paralysis.
• Swallowing assessment (endoscopic or videofluoroscopy) in dysphagia.
• Upper gastrointestinal endoscopy when oesophageal disease is suspected.
• Voice assessment and speech therapy review.
• Tests for human papillomavirus, tuberculosis, and autoimmune disease where relevant.