Videofluoroscopic Swallow Study

The videofluoroscopic swallow study (VFSS, also called the modified barium swallow) is a real time fluoroscopic recording of swallowing. It covers the oral preparation, oral transit, pharyngeal and oesophageal phases. It is done together by a radiologist or radiographer and a speech and language therapist.

The patient sits upright (or in a chair or a seat adapted for a wheelchair) in the lateral projection. They swallow measured amounts of barium in different consistencies, at volumes from 1 to 20 mL, with images recorded at 15 to 30 frames each second.

• Thin liquid (barium suspension of 20 to 40% weight in volume).
• Thickened liquid (nectar and honey thick).
• Puree or pudding.
• A solid (a biscuit or bread coated with barium paste).

An anteroposterior view shows symmetry of pharyngeal movement and the laryngeal vestibule. Compensatory manoeuvres (chin tuck, head turn, effortful swallow, supraglottic swallow and Mendelsohn manoeuvre) and different textures are tried during the study to find a safe way of eating and drinking.

The effective dose is about 0.1 to 0.5 mSv with pulsed fluoroscopy and short screening times (typically 2 to 5 minutes).

Oropharyngeal dysphagia affects about 15% of older people and up to half of people in nursing homes. It affects 50 to 80% of people after stroke, a third or more of those with Parkinson disease, and up to 50% after head and neck cancer treatment. It also affects many infants born prematurely or with neurological disease. Aspiration pneumonia is a leading cause of death in these groups.

The VFSS is the reference imaging test for the mechanism of dysphagia. It shows the movement of the bolus and structures. It detects silent aspiration (aspiration without a cough), which occurs in up to half of aspirating patients. Fibreoptic endoscopic evaluation of swallowing is the alternative test that can be done at the bedside without radiation.

Indications. Suspected oropharyngeal dysphagia (coughing or choking with eating, wet voice, nasal regurgitation, food sticking in the throat, prolonged meals, drooling) in the following settings:

• Stroke.
• Neurological disease (Parkinson disease, motor neurone disease, multiple sclerosis, myasthenia gravis, dementia).
• Head and neck cancer and its treatment.
• Structural lesions (cricopharyngeal bar, Zenker diverticulum, webs, osteophytes, tumours).
• Neuromuscular disease, and after surgery or intubation.

Unexplained recurrent chest infection or pneumonia, weight loss, or dehydration. Assessment of the safety of oral feeding and choice of diet textures and feeding techniques. Planning of treatment such as cricopharyngeal myotomy, dilatation and botulinum toxin. Monitoring of the response to swallowing therapy.

Infants and children with feeding difficulties, failure to thrive, recurrent aspiration, laryngeal cleft, and tracheo oesophageal fistula. Not when the patient cannot sit up, is drowsy or does not follow commands to the extent that the study is unsafe, and not as a screening test.

Contraindications and precautions. Severe, uncontrolled aspiration, poor cough, reduced consciousness or an unprotected airway (risk of aspiration pneumonia): use a bedside assessment and consider endoscopic evaluation or very small volumes of contrast. Allergy to barium products (rare) or to flavouring.

Suspected perforation or fistula: use a non-ionic water soluble contrast instead of barium. Pregnancy: avoid unless essential. Patients who are very fatigued, in pain or in respiratory distress. The study is done with suction, oxygen and resuscitation equipment available.

Patients should be told that barium is not harmful in small amounts but aspiration can cause cough; the barium is generally expectorated or absorbed. Adjust the diet and oral intake plan with the speech therapist.

Preparation and technique. No fasting is needed. The patient is positioned upright in the lateral view with the field covering the lips, hard palate, nasopharynx, tongue base, hyoid, larynx, cervical spine and the upper oesophagus.

Contrast consistencies are given in sequence. Usually start with a small amount of thin or mildly thick liquid and move towards the more difficult consistencies. The study stops if the patient aspirates a significant amount. The anteroposterior view follows. The therapist tests postural and swallowing manoeuvres and different volumes and textures.

Recordings are saved for review frame by frame, and are scored with a validated scale.

Normal appearances. In the oral phase, the lips close, the tongue gathers the bolus and presses it against the palate, and the bolus is propelled backward without spillage.

The pharyngeal swallow triggers when the head of the bolus reaches the faucial arches or the base of tongue (within about 1 second). Then the following happen in sequence:

• The soft palate lifts and seals the nasopharynx.
• The hyoid and larynx rise and move forward.
• The epiglottis tilts down to cover the laryngeal vestibule, and the vocal cords close.
• The tongue base retracts against the pharyngeal wall.
• The pharyngeal constrictors contract in sequence.
• The upper oesophageal sphincter (cricopharyngeus) opens as the bolus passes.

Pharyngeal transit takes under 1 second, and little or no residue remains in the valleculae and pyriform sinuses after the swallow (a trace is normal). No contrast enters the laryngeal vestibule or the airway. The bolus then passes into the oesophagus, with a peristaltic wave.

Interpretation. Observations are reported by phase and by consistency.

• Oral phase: poor lip seal (drooling), impaired chewing, poor bolus formation, spillage of contrast into the pharynx before the swallow, residue on the tongue or palate, and delayed oral transit (over 1.5 seconds).
• Delayed pharyngeal swallow trigger: contrast reaches the valleculae or pyriform sinuses before the swallow starts (longer than 1 second delay is abnormal in many studies). This allows the bolus to fall into the open airway. It is common after stroke.
• Nasopharyngeal reflux: contrast enters the nose because of incomplete palatal closure.
• Reduced tongue base retraction or pharyngeal contraction: residue in the valleculae (poor tongue base movement) or pyriform sinuses and pharyngeal wall (weak constrictors). Residue after the swallow of more than a trace is abnormal, and residue of over 25% of the bolus indicates a risk of post-swallow aspiration.
• Impaired laryngeal elevation or closure: contrast penetrates into the laryngeal vestibule (penetration, contrast on the cranial side of the vocal cords) or passes the vocal cords (aspiration).
• Aspiration can occur before the swallow (delayed trigger), during the swallow (incomplete laryngeal closure) or after the swallow (residue spills into the airway). The timing decides treatment.
• Aspiration without a cough response (silent aspiration) is the most important finding to identify.
• Penetration aspiration scale: 1 (no entry into the airway), 2 to 5 (penetration on the cranial side of the cords, either cleared or not cleared), 6 to 8 (aspiration, from ejected to no effort to eject, with scores 7 and 8 indicating silent aspiration).
• Cricopharyngeal dysfunction: a posterior indentation (cricopharyngeal bar) with incomplete relaxation, upstream residue in the pyriform sinuses, and in some patients a Zenker diverticulum proximal to it.
• Structural lesions: osteophytes of the cervical spine indenting the pharynx, webs, tumour masses, strictures after radiotherapy, tracheo oesophageal fistula, laryngeal cleft, and a pharyngeal pouch.
• Oesophageal phase: a delay, reflux of contrast into the pharynx (pharyngo oesophageal reflux), a dysmotility pattern, or stricture. Refer for a full barium swallow when oesophageal disease is suspected.
• Response to manoeuvres and textures: a chin tuck narrows the airway entrance and widens the valleculae, a head turn to the weak side closes off that pyriform sinus, an effortful swallow improves tongue base movement, and thicker liquids slow transit.
• Document the effective strategies, and choose the safest diet.
• Infants: sucking-swallowing-breathing coordination, nasal regurgitation, laryngeal penetration with thin milk, and bottle or teat factors.

Critical values and findings needing immediate action.

• Silent aspiration of a large volume, or aspiration with respiratory distress, cyanosis or desaturation during the study: stop, suction, sit the patient forward, give oxygen, and monitor; chest radiograph afterwards if symptoms.
• Consistent aspiration of all textures, including saliva: nil by mouth, alternative nutrition (nasogastric or gastrostomy feeding), and urgent multidisciplinary review with the speech therapist and the treating team.
• Evidence of fistula, perforation or leak (contrast outside the pharynx or oesophagus): stop barium, repeat with water soluble contrast, and refer for urgent surgical assessment.
• Mass lesion, tumour or a new structural abnormality: urgent endoscopy, imaging and biopsy.
• Signs of aspiration pneumonia (fever, cough, desaturation) following the study: chest radiograph, antibiotics as indicated, and respiratory support.
• Food bolus obstruction: urgent endoscopy.
• Complete airway obstruction (choking): manoeuvres to clear the airway and resuscitation.

Limitations and artefacts.

• The study samples a few swallows in a short time, in an unnatural setting with barium (which does not taste or feel like food). It may miss intermittent aspiration, or under- or over estimate problems in fatigue, in a full meal or in different foods. A normal study does not guarantee safe swallowing at all times.
• The patient must sit upright, co-operate, and follow commands. Patients who are drowsy, agitated or unable to sit cannot be studied well, and positioning in a wheelchair may distort the view.
• The study shows the oral and pharyngeal anatomy in two dimensions. It poorly shows the pharyngeal wall mucosa, soft tissue lesions, and the vocal cords' function; endoscopy and laryngoscopy are complementary. It does not measure pressure or sensation.
• Interpretation depends on the observers: inter-rater agreement on residue and the penetration aspiration scale is moderate, and structured scoring (such as the penetration aspiration scale) improves reliability.
• Barium has a different viscosity from food and liquids, so the results do not map exactly to meals; the thickness of the barium preparation should be recorded.
• Radiation dose is low but cumulative if repeated, so screening times should be kept short. Fibreoptic endoscopic evaluation of swallowing avoids radiation and can be repeated.
• Aspirated barium is generally not harmful in small amounts but can worsen lung disease; aspirated water soluble hyperosmolar contrast is more dangerous.
• A study done after a long delay may not match the current condition, as swallowing function changes after stroke.

Special groups.

• Stroke patients: most recover swallowing function in 2 to 4 weeks, and early bedside screening is followed by VFSS in those at risk; silent aspiration is frequent.
• Patients with head and neck cancer: pre-treatment baseline and post-radiotherapy follow up; radiation fibrosis causes strictures and weak swallow.
• Patients with neurodegenerative disease: repeated studies track decline and inform decisions on gastrostomy feeding.
• Infants and children: premature infants, cerebral palsy, congenital anomalies and neuromuscular disease. Use a lower dose, a small volume of barium mixed with milk or formula, and feeding by a person known to the infant.
• Older adults with presbyphagia, dementia or frailty: modified textures, positioning and supervised feeding are the main treatments.
• Pregnancy: avoid.
• Regions: stroke and HIV-related and tuberculous causes of dysphagia, caustic ingestion strictures and head and neck cancers present late. VFSS and speech therapy expertise are scarce, so clinical bedside assessment and simple textured diets are often the main approach.

Follow up tests. Fibreoptic endoscopic evaluation of swallowing, laryngoscopy and upper gastrointestinal endoscopy, full barium swallow for oesophageal dysmotility and structural disease, high resolution pharyngeal and oesophageal manometry, chest radiograph, speech and language therapy assessment and treatment (swallowing exercises, postural strategies, texture modified diet, biofeedback),

dietitian review, stroke and neurology workup (CT or MR of the brain, tests for myasthenia gravis, thyroid function), full blood count, albumin, electrolytes and hydration status, tests for gastro oesophageal reflux, dental assessment, and referral to ear nose and throat, neurology, gastroenterology or palliative care services as needed.