Fiberoptic endoscopic examination of swallow (FEES) involves the use of a transnasal fiberoptic endoscope for evaluation of swallowing function. FEES was first introduced by Langmore et al. in 1988 [11] and has gained widespread popularity since its initial introduction. A standard fiberoptic or a distal chip tip endoscope can be introduced through the nasal passage unilaterally to visualize certain events of the oral transfer phase and the pharyngeal phase of swallow (Fig. 4.2). During FEES, it is recommended to place the tip of the endoscope in the pharyngeal area around the midportion of the base of the tongue rather than the laryngeal area to enable visualization of the bolus transit. Clinicians vary regarding their use of topical anesthetic to the nasal mucosa for examination of the swallow function. Topical anesthetic when used is used minimally to prevent any adverse effects of topical anesthetic on the pharyngeal mucosa.

Premature spillage of bolus into the vallecula; base of tongue retraction; penetration of the bolus into the laryngeal vestibule (Fig. 4.3); stasis in the pyriform and vallecular spaces (Fig. 4.4) are some of the physiologic events that can be observed using FEES. In addition to the swallow physiology, FEES enables the clinician for evaluation of laryngeal structures and edema/erythema of the laryngeal structures due to laryngopharyngeal reflux. Typically, boluses of known viscosity are colored with green or blue dye for ease of visualization of possible penetration or aspiration on FEES. Compensatory maneuvers can be used during the test to ascertain their effectiveness in improving the safety of swallowing. FEES is particular beneficial for examining the structures of the larynx, location and severity of the stasis, and in providing biofeedback for the correct use of compensatory maneuvers or training exercises to improve swallow function. Some examples of compensatory strategies that can be used with FEES include modification of the bolus consistency and volume, changing the rate of delivery of the bolus, and modification of the sequence of bolus delivery. Some examples of therapeutic strategies that can be evaluated with FEES include effortful swallow, breath hold maneuver, base of tongue exercises, and thermal-tactile stimulation. FEES is particularly advantageous for evaluating of swallow function in critically ill patients at bedside and in determining the patient readiness for swallowing postradiation or robotic surgery for treatment of oropharyngeal carcinoma.

Flexible endoscopic evaluation of swallow with sensory testing (FEEST) is a modality where both sensory and motor tests for swallowing can be performed, unlike FEES, which only examines the motor component of swallowing. FEEST was first introduced by Aviv et al. in 1993 [12]. FEEST examines the laryngeal closure reflex, which is critical for the airway protection. Pressure and duration of calibrated pulses of air are delivered to the hypopharyngeal tissue, which is known to be innervated by the superior laryngeal nerve that triggers the laryngeal adductor reflex [13]. Several studies have been conducted demonstrating a positive relationship between edema of the hypopharyngeal structures and reduction in the laryngeal airway reflex on FEEST examination [14, 15]. Specialized equipment that delivers calibrated puffs of air is required for FEEST and has not received widespread usage across clinics.