Vocal cord dysfunction and upper-airway mimics

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

The larynx must open during inspiration while protecting the lower airway at other times. In ILO, a trigger provokes transient inappropriate narrowing at the glottic and/or supraglottic level. Triggers include exercise, odour, aerosols, temperature change, talking, laughter, respiratory irritation and emotional arousal. The mechanism is real and involuntary; describing it as 'anxiety' without assessment is both inaccurate and therapeutically unhelpful.

The symptom map is often more useful than the word wheeze. ILO tends to localise to the throat, impair breathing in, produce stridor or a high-pitched sound at peak trigger exposure and resolve rapidly. Lower-airway bronchoconstriction tends to cause chest tightness and expiratory wheeze, often later in exercise or recovery. However, mixed events occur. Objective asthma testing and dynamic laryngeal visualisation answer different questions and may both be needed.

Upper-airway mimics extend beyond ILO. Fixed extrathoracic obstruction from tumour, goitre, subglottic stenosis or bilateral vocal-fold paresis may create persistent inspiratory flattening and stridor. Variable intrathoracic obstruction, tracheomalacia, foreign body, infection, oedema and anaphylaxis demand separate pathways. The clinician must first decide whether the airway is immediately threatened, then distinguish dynamic functional narrowing from structural or neurological disease.

Key points

Inducible laryngeal obstruction is the preferred term for transient inappropriate glottic or supraglottic closure during breathing; 'vocal cord dysfunction' is older and anatomically narrower.
ILO episodes usually begin suddenly with inspiratory difficulty, throat tightness and noisy breathing after a trigger, then settle relatively quickly when the trigger stops.
Asthma more typically causes expiratory airflow limitation and chest symptoms, but ILO and asthma commonly coexist, so an either-or assumption is unsafe.
Laryngoscopy during a typical episode or controlled provocation is central to confirmation; a normal resting larynx does not exclude inducible disease.
For exercise-triggered symptoms, continuous laryngoscopy during exercise is the reference dynamic test because closure may disappear within minutes of stopping.
Inspiratory flattening on a flow-volume loop can support upper-airway obstruction but is insensitive for episodic ILO and must not be used as the sole diagnostic test.
Speech and language therapy is core treatment, teaching laryngeal control, rescue breathing and trigger-specific strategies rather than simply offering reassurance.
Treat confirmed asthma, rhinitis or another contributing disorder on its own evidence; do not escalate corticosteroid because an ILO attack sounds dramatic.
Persistent or progressive stridor, voice change, dysphagia, haemoptysis, weight loss or symptoms during sleep require structural and neurological assessment rather than an ILO label.
A patient-recorded audio or video can clarify timing and sound, but it supports history and does not replace examination or symptom-provoked laryngoscopy.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Laryngeal hypersensitivity

Irritants, perfumes, cold air and previous respiratory illness may sensitise laryngeal pathways; reflux is a reported association but should not be assumed to be causal in an individual patient.

Exercise-related induction

High inspiratory airflow during intense exercise can provoke supraglottic or glottic narrowing, especially in adolescents and athletes.

Psychophysiological factors

Stress and conditioned threat responses can precipitate attacks through altered laryngeal motor control without making symptoms voluntary or fabricated.

Structural and neurological mimics

Tumour, vocal-cord palsy, stenosis, goitre and neuromuscular disease produce fixed or persistent upper-airway obstruction requiring targeted imaging, laryngeal assessment or bronchoscopy according to the suspected level.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Trigger perception
Sensory laryngeal pathways respond excessively to exercise, irritant or internal stimuli in a sensitised person, and the downstream physiological effect determines clinical severity.
2
Inappropriate adduction
Vocal folds or supraglottic tissues narrow during inspiration when they should remain abducted, and the downstream physiological effect determines clinical severity.
3
Turbulent inspiratory flow
The narrowed upper airway generates stridor, throat tightness and abrupt air hunger despite relatively preserved lower-airway expiration.
4
Rapid reversibility
When the trigger ends and laryngeal position normalises, airflow and symptoms often recover faster than in substantial bronchial inflammation.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Inducible laryngeal obstruction

Sudden inspiratory breathlessness, throat constriction, choking sensation or noisy breathing occurs with a reproducible trigger and improves quickly after trigger removal or a learned laryngeal-control manoeuvre.

Exercise-induced laryngeal obstruction

Inspiratory noise and throat limitation peak during high-intensity exercise and fade rapidly after stopping, contrasting with the common post-exercise timing of exercise-induced bronchoconstriction.

Anaphylactic upper-airway oedemaRed flag

Acute airway or breathing difficulty with urticaria, flushing, hypotension, gastrointestinal symptoms or known allergen exposure is anaphylaxis until treated, even when throat tightness resembles previous ILO.

Structural upper-airway obstructionRed flag

Progressive or persistent stridor, voice change, dysphagia, neck mass, haemoptysis, weight loss, sleep symptoms or a fixed flow-volume-loop abnormality requires urgent ENT and airway imaging assessment.

Neurological vocal-fold dysfunctionRed flag

Persistent dysphonia, aspiration, weak cough or stridor after neck or thoracic surgery, intubation or neurological disease may reflect vocal-fold paresis rather than inducible closure.

Coexisting asthma

Variable expiratory wheeze, night symptoms, attacks and objective expiratory airflow variability can coexist with ILO; continuing asthma risk must be assessed independently rather than inferred from laryngoscopy.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
ABCDE assessment with observed breathing sound and phaseFirst step
Why
Identify immediate airway danger and localise airflow limitation.
Interpretation and limitations
Inspiratory stridor suggests upper-airway narrowing, while expiratory wheeze suggests lower-airway obstruction, but mixed sounds occur. Hypoxaemia, swelling, exhaustion, silent airflow or haemodynamic compromise override diagnostic refinement.
02
Flexible nasendoscopy during symptoms or provocation
Why
Visualise dynamic glottic and supraglottic behaviour directly.
Interpretation and limitations
Inappropriate inspiratory closure during a reproduced typical episode supports ILO. Resting or asymptomatic laryngoscopy may be normal; also document structural lesions, secretion management and vocal-fold mobility.
03
Continuous laryngoscopy during exercise
Why
Capture rapidly resolving exercise-induced laryngeal obstruction.
Interpretation and limitations
Visualised glottic or supraglottic closure at the point of usual exertional symptoms confirms the dynamic phenotype and helps tailor laryngeal-control therapy.
04
Quality-assured spirometry with flow-volume loops
Why
Assess lower-airway obstruction and screen fixed upper-airway patterns.
Interpretation and limitations
Inspiratory flattening can suggest variable extrathoracic obstruction and flattening of both limbs can suggest fixed obstruction. Normal loops do not exclude intermittent ILO, and poor effort can mimic flattening.
05
Asthma objective testing or exercise bronchial challenge
Why
Confirm or refute coexisting variable expiratory airflow disease.
Interpretation and limitations
Use the current NICE sequence and a validated exercise protocol. Laryngeal closure and post-exercise FEV1 fall can coexist; treatment should follow the evidence for each mechanism.
06
CT neck and thorax or direct airway evaluation
Why
Define structural obstruction when symptoms are persistent or atypical.
Interpretation and limitations
Imaging and ENT, respiratory or thoracic evaluation should follow suspected anatomical level. Do not delay controlled airway management for imaging when progressive stridor threatens ventilation.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Asthma

Expiratory wheeze, objective variable lower-airway obstruction and a slower recovery support asthma, though both disorders can coexist.

Anaphylaxis

Urticaria, angio-oedema, hypotension or gastrointestinal symptoms with airway compromise indicate a systemic emergency rather than isolated inducible closure.

Fixed central-airway obstruction

Persistent biphasic noise, voice change and fixed flow-loop flattening suggest tumour, stenosis or bilateral vocal-cord palsy.

Foreign body

Sudden choking, persistent focal signs and an aspiration history require urgent airway evaluation, particularly in children.

Dysfunctional breathing

Hyperventilation and breathing-pattern disturbance cause tingling and dyspnoea without demonstrable laryngeal closure, although overlap is common.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01AcuteTreat stridor before naming itFirst stepA patient presents with acute throat tightness, noisy breathing or apparent upper-airway obstruction.

1Perform ABCDE and look for swelling, rash, hypotension, foreign-body history, infection, trauma, voice change, hypoxaemia, exhaustion and altered consciousness.
2Call anaesthetic and ENT support early for threatened airway; treat anaphylaxis immediately with intramuscular adrenaline and follow the local emergency algorithm.
3If observations are stable and the episode matches established ILO, reduce unnecessary stimulation and coach only the person's previously taught rescue-breathing strategy.
4AlternativeReassess physiology and alternative diagnoses after symptoms settle; response to reassurance or bronchodilator alone does not prove the mechanism.

02DifferentiateMap trigger, phase and recoveryRecurrent episodic dyspnoea persists despite asthma treatment or has upper-airway features.

1Ask where tightness is felt, whether breathing in or out is harder, which sound occurs, its relation to trigger or peak exercise and time to recovery.
2Review asthma evidence, attacks and inhaler delivery while screening anaphylaxis, reflux symptoms, rhinitis, cough hypersensitivity, dysphonia, dysphagia and neurological or structural red flags.
3Obtain quality-assured spirometry and appropriate asthma testing, but arrange symptom-provoked laryngoscopy when ILO remains likely.
4For exertional episodes, choose continuous exercise laryngoscopy and consider combined exercise physiology when cardiac, breathing-pattern and bronchial mechanisms remain possible.

03Confirmed ILORetrain laryngeal controlSpecialist assessment supports inducible laryngeal obstruction without an untreated airway emergency.

1Explain the observed laryngeal movement using neutral language, validating symptoms and separating involuntary narrowing from structural damage or imagined illness.
2Refer to an upper-airway speech and language therapist for individual rescue breathing, laryngeal relaxation, trigger desensitisation and voice or throat-care work.
3Practise the selected technique when well, then progressively introduce relevant exercise, odour, speech or environmental triggers under a safe specialist plan.
4Treat evidenced asthma, rhinitis, cough hypersensitivity or reflux disease in parallel, and remove empirical medicines that lack benefit through supervised review.

04PersistentReopen diagnosis after non-responseSymptoms persist despite competent ILO therapy or change in character.

1Check whether the original event was captured and whether the person can deploy the agreed breathing strategy at the true trigger intensity.
2Repeat multidisciplinary review for asthma, structural airway disease, tracheomalacia, dysphonia, dysphagia, chronic cough, dysfunctional breathing and cardiac limitation.
3EscalationEscalate new persistent stridor, voice or swallow change, weight loss, haemoptysis or nocturnal symptoms to ENT and airway imaging rather than intensifying therapy blindly.
4Update the formulation and goals with the patient, measuring function and healthcare use rather than demanding complete symptom extinction.

Key medicines and prescribing safety3 treatments · regimens, roles and cautions

Prevent unnecessary bronchodilator, corticosteroid, antibiotic and sedative exposure when dynamic laryngeal closure is the mechanism.

No routine medicine for isolated ILO

There is no drug dose: use specialist speech and language therapy with individually taught breathing and laryngeal-control techniques.

This statement applies only after airway emergencies, structural disease and coexisting asthma have been assessed. Do not withdraw established asthma treatment abruptly, and never use breathing coaching to delay emergency airway care.

Treat life-threatening allergic airway and circulatory compromise that can mimic an ILO episode.

Intramuscular adrenaline for anaphylaxis

Give 500 micrograms intramuscularly using 1 mg/mL adrenaline in the anterolateral thigh, repeating after five minutes if airway, breathing or circulation problems persist.

Call for emergency help and follow the RCUK anaphylaxis pathway; do not delay when diagnosis is suspected. Intravenous adrenaline is for experienced specialists in an appropriate monitored setting, not routine bolus use.

Treat lower-airway inflammation and bronchoconstriction when objective asthma exists alongside ILO.

ICS-formoterol for independently confirmed coexisting asthma

Use the exact licensed AIR or MART inhaler strength and schedule selected under NICE and the person's written asthma action plan.

It does not directly open an inappropriately closing larynx. Check product-specific limits, technique and adherence; persistent inspiratory attacks despite controlled asthma should prompt laryngeal management rather than repeated corticosteroid escalation.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Unnecessary asthma escalation

Misattributed attacks lead to repeated corticosteroids, high treatment burden and avoidable adverse effects without addressing the larynx.

Emergency airway intervention

Severe-appearing stridor may prompt intubation when diagnosis is uncertain, introducing procedural and critical-care harm, with severity determined by its extent and the patient's underlying reserve.

Exercise and occupational restriction

Fear of abrupt symptoms can limit sport, school, performance and exposure-related work despite preserved lung function.

Coexisting asthma missed

Assuming all symptoms are laryngeal can leave genuine lower-airway inflammation untreated and increase exacerbation risk, and increasing the burden of otherwise local respiratory disease.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Use episode frequency, trigger intensity, recovery time, unscheduled healthcare, activity restriction and confidence deploying rescue breathing as practical ILO outcomes.
Track coexisting asthma separately through attacks, night symptoms, reliever use, objective airflow and inhaled corticosteroid adherence so improvement in one disease is not misread as the other.
Speech and language therapy should review technique acquisition, trigger-specific practice, voice and throat symptoms, and whether the patient can apply strategies outside clinic.
Reassess for structural disease when stridor becomes persistent, occurs during sleep, or is joined by dysphonia, dysphagia, aspiration, haemoptysis, weight loss or neurological change.
Audit oral corticosteroid courses, emergency nebulisers and admissions after diagnosis; reducing inappropriate rescue treatment is an important safety endpoint, not evidence that prior distress was unreal.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Name the phase

Patients often call every musical sound wheeze. Asking them to imitate it and state whether inhalation or exhalation is difficult can immediately redirect testing.

Normal resting scope is expected

ILO is inducible and may resolve before clinic. Provocation should reproduce the patient's typical event safely; otherwise a normal examination has limited exclusion value.

Coexistence explains partial response

A patient may have fewer expiratory symptoms on ICS-formoterol yet retain abrupt inspiratory attacks. This is evidence to test two mechanisms, not automatic treatment failure.

Words can reduce harm

Explaining visible, involuntary laryngeal closure avoids both catastrophic interpretations and dismissive psychogenic labels, improving engagement with retraining and reducing unnecessary emergency treatment.

Persistent stridor is different

Classic ILO is episodic. Continuous or progressive upper-airway noise should trigger investigation for structural narrowing, paresis or other fixed disease even in someone with previous ILO.

11Common pitfallsFrequent interpretation and management errors.

01
Calling acute stridor ILO before excluding anaphylaxis, infection, foreign body and structural airway obstruction.
02
Escalating oral or inhaled corticosteroid repeatedly for inspiratory, throat-centred episodes with no objective asthma change.
03
Excluding ILO because resting laryngoscopy or a symptom-free flow-volume loop is normal.
04
Diagnosing ILO solely from inspiratory loop flattening without checking effort, structure and symptom correlation.
05
Describing the disorder as imaginary or caused simply by anxiety, undermining a real involuntary laryngeal mechanism.
06
Stopping asthma therapy abruptly after laryngeal closure is demonstrated even though both conditions can coexist.