FEES - Short Clinical Note

Definition

• Murray & Nadel's Textbook of Respiratory Medicine, p. 948

Indications

• Dysphagia with suspected neurological cause (stroke, motor neurone disease, Parkinson's, myasthenia gravis)
• Suspected aspiration or silent aspiration
• Post-surgical pharyngeal/laryngeal defects
• Assessment of secretion management (pooling of saliva in piriform fossa)
• Evaluating compensatory swallowing strategies
• Bedside assessment when radiology is unavailable or contraindicated
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, p. 819

Procedure

1. A flexible endoscope is passed transnasally into the nasopharynx/oropharynx
2. The larynx and hypopharynx are visualized at rest - looking for:
   • Structural lesions, vocal fold mobility
   • Pooling of secretions in piriform fossa or vallecula
3. Patient then swallows food/liquid of various consistencies, typically:
   • Thin liquids
   • Thickened liquids (nectar or honey consistency)
   • Pureed food (e.g., applesauce)
   • Mixed consistency (solid + liquid, e.g., fruit cocktail)
   • Dry solid (e.g., cracker)
4. Residue, penetration, and aspiration are noted pre- and post-swallow

• Murray & Nadel's Textbook of Respiratory Medicine, p. 948

What FEES Can Assess

The "Whiteout" Phase - Key Limitation

• Direct visualization of vocal fold closure is not possible during the actual swallow
• Frank aspiration occurring during this phase can be missed
• Murray & Nadel's Textbook of Respiratory Medicine, p. 948

Advantages of FEES

• No radiation exposure (unlike Modified Barium Swallow/MBS)
• Bedside use - does not require a radiology suite
• Well-tolerated by patients (high tolerability)
• Can be performed in ICU/ward settings
• Allows real-time feedback for therapeutic manoeuvres and compensatory strategies
• Can assess laryngeal sensation (with FEESST variant)
• Repeated testing possible without cumulative radiation risk

Disadvantages / Limitations

• Whiteout phase prevents direct visualization during the swallow
• Does not assess the oral phase of swallowing
• Cannot fully evaluate the esophageal phase
• Operator-dependent skill required
• May cause minor patient discomfort on scope insertion

FEES vs. Modified Barium Swallow (MBS) - Comparison

• Murray & Nadel's Textbook of Respiratory Medicine, p. 948-949
• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, p. 819

Clinical Algorithm for Dysphagia Assessment

Key Clinical Points

• Bedside swallow assessment alone by trained SLPs is inadequate to detect aspiration - instrumental testing (FEES or MBS) is required
• Silent aspiration (aspiration without coughing/choking) can only be reliably detected by instrumental methods like FEES
• FEES is the first-line instrumental test in neurological dysphagia due to portability and no radiation
• Results guide diet modification (consistency recommendations) and referral decisions
• Bradley and Daroff's Neurology in Clinical Practice, p. 232

Intratympanic Injection of Gentamicin (ITG) - Short Note

Background & History

• First described by Schuknecht in 1956-57, who injected streptomycin into the middle ear via a microcatheter - vertigo was controlled but severe hearing loss occurred in most patients
• Gentamicin was subsequently adopted because it has high vestibulotoxicity relative to cochleotoxicity, allowing vestibular ablation while sparing hearing better than earlier aminoglycosides
• Also called "partial chemolabyrinthectomy" or chemical labyrinthectomy
• Shambaugh Surgery of the Ear, p. 591; Scott-Brown's Otorhinolaryngology Vol 2, p. 869

Indication

• Tumarkin crisis / drop attacks - sudden falls without loss of consciousness due to acute otolithic dysfunction
• End-stage Ménière's disease with disabling vertigo
• Scott-Brown's Otorhinolaryngology Vol 2, p. 869; Shambaugh Surgery of the Ear, p. 591

Mechanism of Action

• Perilymph concentration reaches 5-10% of the applied solution
• Elimination half-life in perilymph: ~75 minutes
• Selectively concentrated in vestibular hair cells and supporting cells

1. Blocks ion currents through stereocilia
2. Causes adhesion/fusion of stereocilia
3. Ultimately causes hair cell degeneration or extrusion
4. Type I hair cells > Type II (more avid gentamicin uptake)
5. Also acts via NMDA receptor binding (excitotoxicity) and reactive oxygen species production

• Shambaugh Surgery of the Ear, p. 591; Scott-Brown's Otorhinolaryngology Vol 2, p. 869

Injection Technique

1. Anaesthetize the tympanic membrane (TM) using:
   • Topical phenol (Duperstein applicator to pinpoint area), OR
   • Lidocaine injection into external auditory canal, OR
   • EMLA cream (Lidocaine 2.5% + Prilocaine 2.5%)
2. Two-needle technique using a 25-gauge needle:
   • Superior port - to allow air to exit the middle ear
   • Inferior port - for injection of gentamicin
3. Volume: Middle ear holds approximately 0.5-0.8 mL of fluid
4. Post-injection positioning: Patient lies in slight Trendelenburg position with the treated ear up for 30 minutes - keeps gentamicin over the round window membrane and prevents escape through the Eustachian tube
5. Warm the solution to body temperature before injection to reduce the brief episode of vertigo that typically follows

• Injection through an inserted ventilation tube
• Indwelling catheter into the middle ear
• Sponge placed through TM
• Direct injection into round window niche
• Minipumps (for sustained delivery)
• Efficacy does not appear to differ between routes
• Shambaugh Surgery of the Ear, p. 591-592

Dosing Regimens

• Shambaugh Surgery of the Ear, p. 591-592

Efficacy

• Almost one-third of patients will eventually require additional gentamicin injections (unlike surgical labyrinthectomy)
• Hair cells may have some capacity for self-repair after gentamicin
• Scott-Brown's Otorhinolaryngology Vol 2, p. 868-869; Shambaugh Surgery of the Ear, p. 591

Complications & Risks

• SNHL risk is lowest with titration (single-dose) therapy and highest with multiple daily dose regimens
• Hearing loss must be weighed against the benefit of vertigo control when selecting candidates - ITG is less preferred in patients with useful residual hearing in the only hearing ear
• Scott-Brown's Otorhinolaryngology Vol 2, p. 869; Shambaugh Surgery of the Ear, p. 591

ITG vs. Vestibular Neurectomy - Comparison

• Scott-Brown's Otorhinolaryngology Vol 2, p. 869

Treatment Algorithm Position

1. Medical therapy - low-sodium diet, diuretics, vestibular suppressants
2. IT dexamethasone - if medical failure (Grade A recommendation; 80% vertigo control, no hearing risk)
3. IT gentamicin (titration) - if IT dexamethasone fails (Grade A recommendation)
4. Surgery - endolymphatic sac decompression, vestibular neurectomy, or labyrinthectomy for extreme refractory cases

• Scott-Brown's Otorhinolaryngology Vol 2, p. 868-869

Botulinum Toxin in ENT - Short Note

Pharmacology Basics

• Produced by Clostridium botulinum - eight serotypes (A-H); Type A (BoNT-A) has the widest clinical use
• Mechanism: Prevents presynaptic release of acetylcholine by cleaving SNAP-25 protein, blocking vesicle fusion at the nerve terminal
• Acts on both neuromuscular junctions (motor paralysis) and parasympathetic nerve terminals (glandular secretion reduction)
• Onset: 2-3 days after injection
• Duration: 3-9 months (varies by product and tissue type)
• Repeated injections possible; effect is temporary and reversible
• Cummings Otolaryngology Head and Neck Surgery

ENT Applications - Overview

1. Spasmodic Dysphonia (SD)

• Adductor SD (most common): involuntary adduction of vocal folds causing strained, strangled voice
  • Inject thyroarytenoid (TA) muscle - bilateral or unilateral
  • Route: Transcricothyroid membrane approach (most common); needle angled superolaterally into adductor muscle group
  • Produces controlled, temporary paresis restoring voice fluency
• Abductor SD: involuntary abduction causing breathy, whispering voice
  • Inject posterior cricoarytenoid (PCA) muscle
• Injection guidance: EMG guidance or direct laryngoscopy via nasendoscope
• Effect lasts ~3-6 months; repeat injections required
• Scott-Brown's Otorhinolaryngology, p. 1033

2. Sialorrhea (Drooling)

• BoNT-A injected into parotid and/or submandibular glands
• Causes chemical parasympathetic denervation of glands - reduces saliva production
• Delivery techniques:
  • Anatomic landmarks + manual palpation
  • Ultrasound guidance (preferred - most accurate)
  • EMG guidance
• Can be performed outpatient/clinic without general anaesthesia (GA may be needed for uncooperative patients)
• Duration: 3-9 months; re-injection required for recurrence
• ~10% non-responders regardless of dose
• Important complication: dental caries - salivary pH drops significantly, increasing acid and reducing protective saliva volume; provide special dental care

• Dysphagia
• Aspiration pneumonia
• Muscle weakness distal to injection (from toxin diffusion into surrounding neck muscles)

• Cummings Otolaryngology Head and Neck Surgery

3. Frey Syndrome (Gustatory Sweating)

• Complication of parotidectomy - aberrant reinnervation of sympathetic sweat glands by parasympathetic salivary nerve fibers
• Patient sweats and flushes over the face when eating
• Confirmed by Minor starch-iodine test
• BoNT-A injected intracutaneously over the affected facial skin
• Described as effective in severe cases not responding to topical antiperspirants or glycopyrrolate
• Cummings Otolaryngology, p. 1521

4. Cricopharyngeal Spasm / Dysfunction

• Cricopharyngeus fails to relax during swallowing - causes dysphagia, especially post-laryngopharyngectomy
• BoNT injection into cricopharyngeal muscle relaxes the UES (upper esophageal sphincter)
• Routes: endoscopic or percutaneous
• Indications: functional stenosis/spasm; used if dilation fails or at second occurrence of spasm
• Often combined with dilation; may avoid the need for open surgical cricopharyngeal myotomy
• Cummings Otolaryngology, p. 1950

5. Post-Laryngectomy Tracheoesophageal Voice Failure (Pharyngospasm / Hypertonicity)

• After total laryngectomy + tracheoesophageal puncture (TEP), some patients develop pharyngeal/neoglottic hypertonicity - the vibratory segment goes into spasm, preventing tracheoesophageal voice
• Confirmed by videofluoroscopy + lidocaine injection test
• BoNT (Botox/Dysport) injected at 3 sites along the myotomy line (from cricopharyngeus level down to below TEP), unilaterally
• Dose adjusted for degree of hypertonicity, neck fibrosis, and type of reconstruction
• A single treatment is often sufficient for continued tonic voice; can be repeated

• Scott-Brown's Otorhinolaryngology Head & Neck Surgery, p. 1033

Injection Approaches to the Larynx (for BoNT)

General Complications of BoNT in ENT

Key Summary Points

1. BoNT-A is the standard clinical preparation; acts by blocking ACh release via SNAP-25 cleavage
2. Effect begins in 2-3 days, lasts 3-9 months - temporary and repeatable
3. Adductor spasmodic dysphonia is the landmark ENT application - inject TA muscle via transcricothyroid approach
4. Sialorrhea treatment via intraglandular injection is safe and effective; US guidance preferred; watch for dental caries and aspiration
5. Frey syndrome, cricopharyngeal spasm, and post-laryngectomy hypertonicity are other important ENT indications
6. FDA warning: risk of dysphagia and aspiration pneumonia from toxin spread - always use minimum effective dose