Fiberoptic imaging was initially developed in the 1930s by a medical student named Heinrich Lamm. Lamm intended to visualize inaccessible regions of the body with his invention. Fiberoptic imaging became more visible in medical literature during the 1950s with further innovations by Hopkins and Storz.  By 1963, Hirschowitz designed a medically functional fiberoptic scope with higher resolution, lighting, suction, and instrument ports.  Current fiberoptic nasopharyngoscopes are lighted, are flexible with 2-way articulation, provide inline viewing with photo and video capabilities, and can have a distal diameter as small as 2 mm.
Alternative visualization techniques include indirect laryngoscopy and laryngoscopy by angled telescope.  The traditional indirect laryngoscopy relies on a single hand-held mirror to reflect the structures of the larynx to sight. Laryngoscopy by angled telescope allows a direct view of these structures also. Though these techniques may be less expensive and easier to use initially, fiberoptic nasopharyngoscopy (for the purposes of simplicity, indirect fiberoptic laryngoscopy is included under this heading) provides clearer visualization and better access to nasopharyngeal anatomy. The image below depicts an adult fiberoptic nasopharyngoscope.
Fiberoptic nasopharyngoscopy can allow visualization of the following structures: nasal cavity, septum, middle meatal space and infundibulum, frontal recess, sphenoid ethmoid recess, turbinates, posterior choanae, eustachian tube orifices, adenoids, nasopharynx, posterior surface of the uvula and palate, velopharyngeal valve, adenoids, base of the tongue, pharyngeal and lingual tonsils, vallecula, pyriform spaces, epiglottis/supraglottis, glottis with mobility or immobility of the vocal folds and arytenoids, and immediate subglottis.
The pharynx is a fibromuscular tube that is semicircular in cross section and is situated directly anterior to the vertebral column. It extends from the skull base to the lower border of the cricoid cartilage. Six muscles are predominantly responsible for the voluntary actions of the pharynx: three pharyngeal constrictor muscles that are roughly circularly layered on top of one another and three vertically oriented muscles (stylopharyngeus, salpingopharyngeus, and palatopharyngeus).
The pharynx serves as a continuation of the digestive cavity, providing a route from the oral cavity proper to the esophagus. In addition, the pharynx communicates with the nasal cavity, the middle ear cavity, and the larynx. The pharynx is often described from an exterior view and an interior perspective. Based on the location, the interior of the pharynx is often separated into three sections—the nasopharynx, oropharynx, and laryngopharynx.
Fiberoptic nasopharyngoscopy is indicated when visualization of the nasopharyngeal anatomy is needed for diagnosis, treatment, or both. 
In the nasal cavity, fiberoptic nasopharyngoscopy can visualize polyps, tumors, foreign bodies, or sources of epistaxis.
In the nasopharynx, the scope can help identify suspected tumors or adenoidal hypertrophy.
In the oropharynx or hypopharynx, fiberoptic nasopharyngoscopy may be used to evaluate foreign bodies and potential airway obstruction from such etiologies as neoplasm and epiglottitis, obstructive sleep apnea, dysphagia, dysphonia, tonsillar hypertrophy, glossoptosis, or laryngomalacia.  It may also assist in the evaluation of the severity of angioedema. 
Images from nasopharyngoscopy in a 30-day-old infant shown in the images below.
In the vocal cords, polyps, nodules, masses, and paralysis can also be identified with fiberoptic nasopharyngoscopy.
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Relative contraindications include coagulopathies that might result in significant bleeding if even minor trauma occurs during the procedure. In the setting of craniofacial trauma, the benefits should be carefully weighed against the risks of inadvertent intracranial instrumentation and exacerbation of nasopharyngeal injuries.
Nasopharyngoscopy is otherwise considered a benign procedure with few contraindications and complications in experienced hands.
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Topical agents act as an anesthetic and can also reduce bleeding secondary to instrumentation. 
- These agents most commonly include phenylephrine nasal spray (Neo-Synephrine), oxymetazoline nasal spray (Afrin), and lidocaine. For maximum effectiveness, lidocaine can be placed on cotton swabs or pledgets in the nose and allowed to absorb into the mucosa for several minutes.
- A combination of 1% phenylephrine and 4% lidocaine is commonly used (in a 50/50 mixture).
Though procedural sedation may be necessary in young children, bracing the child during the procedure is usually sufficient.
Fiberoptic nasopharyngoscopes, as shown below, can be selected in diameters ranging from 1.9 mm to 6 mm and in adult and child lengths. Starting with a smaller scope in a child may help minimize trauma.
Additional equipment includes a camera (which can be attached to the viewing port of the scope), a video monitor (like the one below), a recording unit, and a image printer.
The clinician should also be prepared for the specific objectives of the procedure. For example, equipment such as a suction device, angled McGill forceps, and a Kelly clamp should be available for foreign body removal.
During nasopharyngoscopy, the patient is usually sitting upright but can also be lying supine. If the patient is seated, a posterior headrest should be used to stabilize the head during the procedure, and the head should be stationed in sniffing position to bring the larynx and pharynx into optimal alignment.
A right-handed clinician should hold the nasopharyngoscope in the right hand and stand to the left of the patient. The left hand can then rest on the patient’s nose to act as further stabilization and help guide the nasopharyngoscope and twist it to assist in guidance. Orientation of the distal tip may be controlled with the index finger or thumb of the right hand through the controller. Positioning is shown in the image below.
If the patient is supine, the clinician should stand at the head of the bed, also left of midline, with similar endoscopic control by the right hand. In this position, however, the likelihood of poor visualization of structures caudad to the nasopharynx is greater because of a posterior resting state of the base of the tongue.
After proper positioning and application of anesthesia to the naris, lubricant should be applied to the nasopharyngoscope.
To prevent visual obstruction, do not apply lubricant to the distal 2 cm.
Some practitioners do not use lubrication.
The patient should focus on oral respiration while the scope is inserted along the floor of the nose as in the placement of a nasogastric tube.
If the lens becomes fogged, instruct the patient to swallow and then gently wipe the lens against the nasal mucosa or tongue (wiping in the hypopharynx can activate the gag reflex).
Silicone spray also helps with fogging.
The scope should pass between the inferior turbinate and the septum until the soft palate can be viewed. The ease of this passage depends on the patient’s anatomy. Sometimes the scope should be passed above the inferior turbinate if it is easier to pass in this location.
Direct the tip inferiorly to view the oropharynx and advance further. Here, the palatine tonsils appear laterally along the palatopharyngeal arches. Directly midline, the proximal tongue and the lingual tonsil can be visualized. Further caudal movement brings into view the epiglottis and the vallecula. Scan posteriorly to reveal the vocal cords, aryepiglottic folds, and pyriform sinus.
For a better view of the anatomy, ask the patient to 1) protrude the tongue, 2) blow out the cheeks, and 3) vocalize the letter e.
Before removing a foreign body, the object should be clearly visualized without obstruction by mucous or blood. The foreign body should be judged easily accessible based on the practitioner’s experience, the grasping instruments available, the patient’s anatomy, and the level of cooperation of the patient.
An inexperienced practitioner, an uncooperative patient, difficult anatomy, inadequate instrumentation, or any combination of these, can lead to airway trauma or worsened obstruction secondary to laryngospasm and further displacement of the foreign body, leading to aspiration.
Nevertheless, a small foreign body can sometimes be removed with the scope using the side port for forceps. Further judgment is required to determine whether the foreign body can pass through the nose or needs to be extracted through the mouth.
For evaluation of obstructive sleep apnea, the Müller maneuver can help identify patients who could benefit from surgery. The patient should force inspiration against a closed mouth and nose, thereby evoking retropalatal collapse. However, these findings are not clearly correlated with the need for surgical intervention, and the subject remains controversial. [13, 14] The technique has often been questioned for its ability to be reproduced by the examiner. 
Another application for nasopharyngoscopy is assessment of velopharyngeal insufficiency. While the patient counts aloud or repeats a specific phrase, the nasopharyngoscope can be used to assess the pattern of velopharyngeal closure.  Recent studies also seem to suggest that the use of nasopharyngoscopy in addition to conventional speech therapy help to improve velopharyngeal closure during articulation, as it allows patient to have “an idea of inner percept of the sphincter closure mechanism.” 
Fiberoptic nasopharyngoscopy has also been reported as a tool in the evaluation of high-risk patients with angioedema. Visualization of laryngeal structures coupled with an accurate history and physical examination was a reliable modality for identifying high-risk patients who required either ICU admission or airway intervention.  Laryngeal edema and pharyngeal edema are ominous signs for both respiratory distress and possible airway protection. 
Fiberoptic endoscopic evaluation of swallowing (FEES) has emerged as a comparable alternative to video fluoroscopy and modified barium swallow in the evaluation of dysphagia.  By visualizing the pharynx during swallowing, the patient can be assessed for delays in swallowing, laryngeal penetration, aspiration, and pharyngeal residue after swallowing. It is important to note that topical nasal anesthesia is currently controversial for this procedure owing to concern for the risk of desensitizing the pharyngeal or laryngopharyngeal mucosa, which would thereby skew results. However, current American Speech-Language-Hearing Association (ASHA) guidelines allow physicians to choose its use.  Supraglottic sensation can be tested in the face of suspected brainstem stroke and aspiration risk.
Note the video presentations below.
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Since patients are awake during fiberoptic nasopharyngoscopy, they can be easily startled by the invasive nature of the procedure. A clear explanation of the succeeding steps helps mitigate their concern.
Nares are not always symmetrical. Selection of the more patent nostril reduces trauma.
Minimize scope fogging with silicone drops and warming of the tip.
Avoid contact with the epiglottis and vocal cords.
Remember to compare symmetry and closely explore signs of trauma, hyperemia, and masses.
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Though complications are uncommon, the most frequently seen complications include tearing, coughing, and, less frequently, epistaxis secondary to mucosal trauma (a smaller diameter scope can help mitigate this problem). 
- As stated previously, vasoconstrictors can be used before laryngoscopy to minimize minor trauma and bleeding.
- If the camera is obscured or the scope is facing resistance, increasing force should not be used.
A residual foreign body sensation, transient laryngospasm, and vasovagal syncope are also potential complications.
- Laryngospasm is rare, with an incidence of approximately 1%,  and is usually self-limited but can lead to desaturation and temporary airway obstruction. Laryngospasm is thought to be evoked by excitation of the afferent fibers to the larynx and can be mitigated by jaw thrust and positive airway pressure until resolution or definite treatment. 
- Though existing studies show excellent success with laryngoscopy in removing foreign bodies,  these results are achieved in the hands of experienced operators. Those who do not use this technique frequently should be aware of the potential hazard of further impacting a foreign body and worsening an airway obstruction. For this reason, the equipment and personnel necessary to establish an alternate airway if the primary airway is lost should be available.
Damage to anatomic structures is more common with rigid laryngoscopy and is rarely seen with nasopharyngoscopy.