To do the sensory evaluation, the endoscope is positioned so that the port is aligned over the aryepiglottic fold. Discrete pulses of air are delivered at sequentially increased pressures to the mucosa innervated by the superior laryngeal nerve (SLN), thus eliciting the laryngeal adductor reflex. This portion of the evaluation establishes the patient’s sensory threshold. The motor evaluation will be completed by giving liquids and foods of varying consistencies while the clinician monitors oral transit time, inhibition of swallowing, laryngeal elevation, spillage, reflux, aspiration, and ability to clear residue, among other factors.
Explore This IssueDecember 2007
A major reason to do the sensory testing, said Dr. Aviv, is to determine whether reactions to the air pulse are asymmetrical. “Often, when we see asymmetry, this gives us a clue that there could be pressure on the vagus nerve or on a branch of the vagus nerve that governs sensation.” Additional imaging procedures, such as an MRI of the brain, neck, and chest, might be the next step in a diagnostic workup where asymmetrical responses to sensory testing have been recorded.
Dr. Aviv, who trains clinicians in the technique at his center, said that an experienced endoscopist can learn how to do laryngeal sensory testing within 15 to 20 minutes. Dr. Burkhead confirms that the learning curve is negligible.
Who Can Benefit?
FEESST is now a well-established technique for diagnosing problems with swallowing and developing appropriate management plans, said Dr. Aviv. For instance, one randomized prospective study of 164 outpatients revealed that in the subgroup of stroke patients, 29.2% of patients receiving the MBS evaluation developed aspiration pneumonia, versus only 4.76% of those in the FEESST-managed group.4
The technique is especially valuable in the largest dysphagia populations—the elderly and stroke patients. Reimbursement by Medicare is approved in patients with dysphagia who are at risk for aspiration; patients with stroke or other central nervous system derangement and associated impairment of speech and swallowing; patients without CNS disorders, but who have documented difficulty in swallowing; and patients with a history of aspiration or aspiration pneumonia. In the nursing home setting, FEESST can furnish valuable data when making clinical decisions about placement or removal of gastrostomy tubes, dietary management of impaired patients, and planning and evaluation of appropriate therapy programs.
Dr. Aviv finds FEESST beneficial in patients with a variety of laryngeal complaints, such as cough, hoarseness, throat clearing, thick phlegm in the throat, and even postnasal drip. Dr. Burkhead works largely with head and neck cancer patients, and has found FEESST helpful for pre- and post-radiation assessments. “Many of our patients have fibrotic changes due to their radiation treatments,” she explained, “and the sensory testing is valuable in helping us understand how a patient’s sensation is changing over time.”