Investigations in Swallowing Disorders

Introduction

A. CLINICAL / BEDSIDE ASSESSMENTS

1. Clinical Swallowing Examination (CSE)

• Full history: onset, progression, solid vs. liquid, pain, regurgitation, voice change, weight loss
• Oral cavity examination: dentition, tongue mobility, palatal movement, gag reflex
• Voice quality assessment (wet/gurgly voice suggests aspiration)
• Assessment of cognition and posture

2. Water Swallow Test (WST)

• Patient swallows 30-100 ml of water
• Observation for: cough, wet voice, throat clearing, choking
• 30 ml WST: ~50% sensitivity, 80-92% specificity for aspiration
• 100 ml WST in head and neck cancer: 67% sensitive, 46% specific
• Useful as a simple screening and adjunct to instrumental testing

3. Blue Dye Test

• Used in patients with tracheostomies
• Blue food dye mixed with food/drink; any dye suctioned from trachea indicates aspiration
• Simple but has low sensitivity for silent aspiration

B. INSTRUMENT-BASED INVESTIGATIONS

1. Videofluoroscopic Swallowing Study (VFSS) - GOLD STANDARD

• Patient positioned in usual eating/drinking posture; no fasting required
• Boluses mixed with barium; given in increasing volumes and different textures
• Mainly lateral view; AP view assesses symmetry
• Compensatory manoeuvres (e.g. chin tuck) can be tested during the study

• Oral, pharyngeal, and upper oesophageal phases of swallowing
• Hyolaryngeal excursion
• Cricopharyngeal/UES opening
• Laryngeal penetration and aspiration
• Pharyngeal residue
• Structural abnormalities: Zenker's diverticulum, cricopharyngeal web, cervical osteophytes, pharyngo-oesophageal fistulae

• Real-time dynamic assessment of all swallowing phases
• Can test compensatory strategies
• Assessment of both oral/pharyngeal AND oesophageal phases

• Radiation exposure (equivalent to ~2 cervical spine X-rays per 3 minutes)
• Expensive; requires multidisciplinary team (radiologist + SLT + ENT)
• Barium properties differ from normal food/liquids
• Not suitable for bedbound patients or those unable to cooperate
• Contraindicated in pregnancy

2. Fibre-optic Endoscopic Evaluation of Swallowing (FEES)

• No fasting required; patient in usual eating position
• No routine anaesthetic (to avoid desensitizing mucosa); topical decongestant to nares only if needed
• Endoscope advanced through inferior meatus
• Food dyed with food colouring to enhance visibility
• Four views assessed: nasal passage (velum elevation), velopharyngeal port, oropharynx, hypopharynx/larynx

• Pharyngeal anatomy and mucosal lesions
• Secretion management (pooling - indicator of aspiration risk)
• Laryngeal penetration and aspiration (before/after swallow; during the swallow is the "white-out phase")
• Post-swallow pharyngeal residue
• Effect of fatigue (scope held in position for prolonged assessment)
• Laryngopharyngeal sensation

• Portable - can be done at bedside/ICU
• No radiation
• Direct mucosal visualization
• Cheap and repeatable
• Patient can view their own swallowing - useful for biofeedback therapy

3. FEES with Sensory Testing (FEESST)

• Modification of FEES
• Air pulses of varying intensity, duration, and frequency delivered through an additional port in the endoscope
• Quantitative assessment of laryngopharyngeal sensation
• Determines laryngeal adductor reflex threshold
• Useful when sensory dysfunction is suspected as cause of aspiration

4. Barium Swallow (Traditional)

• Both static and dynamic components
• Distension with liquid barium (or thick barium + gas for double contrast)
• Assesses intrinsic disease: tumours, diverticula, webs, strictures, dysmotility
• Assesses extrinsic disease: cervical osteophytes, thyroid enlargement
• Motility assessed in multiple positions including recumbent (to eliminate gravity effect)
• Classic findings:
  • Zenker's diverticulum: posterior pharyngeal pouch at Killian's dehiscence
  • Achalasia: "bird's beak" appearance at LES with dilated oesophagus
  • Diffuse oesophageal spasm: "corkscrew" oesophagus
  • Carcinoma: shouldering/rat-tail stricture
  • Pharyngeal web (Patterson-Brown-Kelly/Plummer-Vinson): thin mucosal fold in postcricoid region

5. Oesophageal Manometry (Oesophageal Motility Study)

• High-resolution manometry (HRM) is now the standard
• Measures intraluminal pressures along the entire oesophagus and sphincters
• Essential for diagnosing primary oesophageal motility disorders

• Dysphagia not explained by endoscopy
• Suspected oesophageal motor disorder

6. Upper GI Endoscopy (OGD)

• Direct visualisation of oesophageal, gastric, and duodenal mucosa
• Indicated when structural/mucosal pathology is suspected
• Detects: carcinoma, oesophagitis, strictures, Barrett's oesophagus, webs, extrinsic compression
• Allows tissue biopsy
• Therapeutic: dilatation of strictures, Botox injection into LES (achalasia)

7. CT Scan and MRI

• Structural assessment of pharynx, oesophagus, mediastinum, and lungs
• Detects: oropharyngeal/hypopharyngeal tumours, lymphadenopathy, mediastinal masses
• CT chest: assesses aspiration pneumonia

• Intracranial pathology causing neurogenic dysphagia (stroke, tumour, MS, brainstem lesions)
• High-speed dynamic MRI: used experimentally for functional swallowing analysis
• Non-invasive; provides both anatomical and functional information
• Limitation: patient must swallow supine; not normal swallowing position; costly

8. Electromyography (EMG)

• Assesses neuromuscular function of swallowing musculature
• Indicated in neuromuscular causes of dysphagia (e.g. myasthenia gravis, motor neurone disease, polymyositis)
• Surface EMG can be used as biofeedback during swallowing therapy

9. Nasendoscopy / Laryngoscopy (Rigid/Flexible)

• Direct inspection of nasopharynx, oropharynx, hypopharynx, larynx
• Identifies structural lesions: tumours, submucosal masses, vocal cord palsy, postcricoid oedema
• Essential in the ENT workup prior to undertaking FEES

10. Laboratory Investigations

• CBC, ESR, CRP: General screening; inflammatory/infective causes
• Thyroid function tests: Thyroid goitre causing extrinsic compression
• ANA, anti-dsDNA, anti-Scl-70: Connective tissue disease (scleroderma, SLE, dermatomyositis)
• Anti-AChR antibodies: Myasthenia gravis
• CK, aldolase: Inflammatory myopathy
• Serum iron, ferritin: Plummer-Vinson syndrome (postcricoid web in iron deficiency anaemia)
• Blood glucose, HbA1c: Diabetic autonomic neuropathy

Summary Table

Key Points for the Exam

1. VFSS is the gold standard for oropharyngeal dysphagia; FEES is the complementary bedside tool.
2. FEES and VFSS are complementary - together they give the most complete picture of swallowing physiology.
3. Barium swallow is the first-line investigation for oesophageal dysphagia (structural lesions).
4. Manometry is essential for diagnosing primary oesophageal motility disorders.
5. Penetration-Aspiration Scale (PAS) is the validated scoring system used with both VFSS and FEES.
6. FEES cannot visualize the actual moment of the pharyngeal swallow (white-out phase); VFSS can.
7. For Plummer-Vinson/Patterson-Brown-Kelly syndrome: barium swallow shows postcricoid web + check serum iron/ferritin.
8. For Zenker's diverticulum: barium swallow is diagnostic (posterior pouch at Killian's triangle).
9. For neurogenic dysphagia: MRI brain/brainstem is indicated.
10. For achalasia: manometry (high LES pressure + aperistalsis) + barium (bird's beak sign).