م الرحيميبسم هللا الرحWad Medani Pediatric hospital

Unit Prof : Ahmed Alnour Dr. Hisham Alomda

Dr. Abdalsalam

UNDERSTAND, EVALUATE, AND DIAGNOSE THE

CAUSES OF STRIDOR IN PEDIATRICS

Presented by Dr. Mogahed hussein

DEFINITION

Stridor is typically a high-pitched, monophonic noise caused by turbulent airflow through a

partially obstructed extrathoracic airway, heard predominantly on inspiration.

Although obstruction of large intrathoracic airways (ie, main-stem bronchi, mid and distal

trachea) can produce a similar noise on expiration, these lesions are, Wheezing, and will not be

discussed here.

Mechanism

During the normal respiratory cycle, rhythmic expansion and contraction of the thorax leads to dynamic changes in thoracic pressures, allowing air to flow into and out of the lungs.

During expiration the volume of the thoracic cavity decreases, creating positive pressures within the thorax.

Airways located within the thorax are directly subjected to these positive pressures and thus are more prone to obstruction during expiration, leading to turbulent airflow and wheezing.

Mechanism

On inspiration the thoracic cavity expands, resulting in negative intrathoracic pressures and

improved patency of intrathoracic airways

However, because the intraluminal airway pressure drops to allow inflow of air, and because

the extrathoracic airways (nose, nasopharynx, oropharynx, and larynx) may collapse from

transmitted negative intrathoracic pressures, this portion of the airway is susceptible to

obstruction, and thus stridor, during inspiration.

Mechanism

Because the extrathoracic airways extend from the nose to the proximal trachea, high pitched

laryngeal stridor must be differentiated from other abnormal inspiratory noises, such as stertor,

a noisy, rumbling-type noise similar to snoring, which can be heard with partial airway

obstruction in the oropharynx or nasopharynx.

Accurately recognizing stridor will facilitate the ensuing diagnostic tests, given that the offending lesion is likely to be in or around the glottic region, a relatively focused anatomic area.

DIFFERENTIAL DIAGNOSIS

Because stridor reflects obstruction of a large centralized airway and can range in severity from

mild to life-threatening, ensuring airway patency should precede the generation of a differential

diagnosis.

For the child who has signs of severe respiratory compromise—distressed appearance, severe

retractions, nasal flaring, pallor or cyanosis, altered mental status—initial measures should focus

on maintaining the airway and, if possible, relieving the obstruction.

NOTE

Only personnel skilled at airway management should attempt intubation, if required, and such a

procedure should be performed in as controlled a setting as possible. In select situations for

which medical intubation might prove difficult (ie, suspected epiglottitis in a patient with high

fever, drooling, and severe respiratory distress), surgical support should be present before

airway manipulation in the event that tracheostomy is required

DIFFERENTIAL DIAGNOSIS

The most common causes of stridor in the pediatric age group, laryngomalacia and viral croup,

which mostly diagnosed by focused history and physical examination (see Evaluation).

The differential diagnosis of stridor is extensive and includes anything that obstructs the

extrathoracic airway, so identifying select patients who have less common causes of obstruction

and thus require specific diagnostic tests and different management is important.

DIFFERENTIAL DIAGNOSIS

Laryngomalacia Vocal cord dysfunction Subglottic stenosis

Laryngeal papillomatosis Glottic cysts Laryngeal webs

Subglottic hemangiomas Foreign bodies Retropharyngeal abscesses

laryngeal fractures.

EVALUATION

History …. Age of onset

Age of initial presentation and a description of the events surrounding the onset of symptoms

can provide important clues to the underlying diagnosis.

A commonly encountered patient is one whose stridor is preceded by fever, upper respiratory

symptoms, and a barky or seal-like cough.

This history, which may include repeated and similar episodes in the past, is consistent with

viral croup and is easily recognized by an experienced pediatrician.

History

Stridor beginning in the first few weeks of life that is present only during specific phases of

alertness such as eating, sleeping, or excitement suggests congenital laryngomalacia as the

underlying cause.

Indeed, laryngomalacia is the most common cause of congenital stridor in infancy.

In comparison, continuous stridor that begins soon after birth might suggest a congenital and

fixed lesion such as a laryngeal web or, particularly in an infant with cutaneous hemangioma,

subglottic hemangioma (obstruction associated with subglottic hemangiomas typically is mild at

birth and worsens over the first 6 months of life).

History

Stridor that develops shortly after a prolonged intubation likely results from subglottic stenosis

or granulation tissue and is often seen in premature infants who required mechanical

ventilation during the neonatal period.

A less common but important patient to recognize is one with a history of Arnold-Chiari

malformation or hydrocephalus.

Because increasing intracranial pressure can result in bilateral vocal cord paralysis, such patients

should receive appropriate and emergent care to prevent brainstem herniation.

History

Similarly, a stridulous toddler with a history of choking or placing small objects in the mouth

should be evaluated for the presence of a foreign body.

Recurrent respiratory papillomatosis is also usually associated with stridor or hoarseness 2 to 3

years after birth, although the infection is acquired through vertical transmission in the birth

canal from maternal cervical human papillomavirus infection.

History ….. progression

In addition to their onset, the chronicity and progression of symptoms can help identify the

underlying cause and can be particularly helpful for patients with presumed laryngomalacia or

viral croup who do not follow the expected clinical course.

Stridor caused by laryngomalacia is typically intermittent and worsens over the first several

months of life.

As the child becomes older, such episodes become less severe and less frequent.

History

Indeed, for most patients with laryngomalacia, symptoms will completely resolve by the first

birthday.

Similarly, the likelihood of developing stridor caused by viral croup lessens with age.

When the pediatrician is faced with a child whose stridor worsens or persists rather than

improves, coexisting or alternate diagnoses should be considered, and appropriate diagnostic

testing should be initiated.

History

Unlike laryngomalacia, natural resolution of the hemangioma, and thus the stridor, may take

several years rather than months.

History of a hoarse voice or cry suggests glottic disease and might result from chronic

irritation of the vocal cords.

Other clues that suggest more ominous conditions include constant stridor, failure to thrive,

difficulty swallowing, and severe and sudden onset of symptoms.

Last, onset of stridor in an older child or adolescent with no previous history should prompt a

more thorough evaluation.

Physical Examination

Laryngeal stridor represents airway obstruction at the level of the supraglottis, glottis, or

subglottis.

Although these anatomic regions can be difficult to examine without the use of specific

diagnostic tests, several clues from thorough physical examination can help confirm suspicions

elicited on history.

Physical Examination

General inspection of the patient should include an assessment of position—extension of the

neck is often described in patients with a serious infection such as epiglottitis or

retropharyngeal abscess—as well as any drooling, which might suggest mass effect or edema in

the posterior pharynx causing dysphagia in addition to the stridor (of note, these patients often

exhibit stertor rather than stridor).

Because such entities can be difficult or even dangerous to visualize, attention should focus on

keeping the patient calm and maintaining the airway.

Physical Examination

An oropharyngeal examination might reveal a retropharyngeal bulge, an enlarged epiglottis or a

lateral displacement of the uvula, and swelling of a tonsillar pillar from an underlying infection

in patients with acute onset of stridor.

External examination of the neck might show suprasternal retractions when obstruction is

severe and may also reveal displacement of the larynx, a mass obstructing the airway, or signs

of trauma.

Physical Examination

Finally, the quality of the voice should be noted; given that hoarseness, aphonia, or a weak cry

suggests vocal cord disease, one should examine the skin for any cutaneous lesions such as

hemangiomas.

Lastly, improvement of stridor with a jaw thrust could suggest pathology in the region of the

epiglottis as opposed to the subglottis.

Objective Testing

Although a detailed history and physical examination are often sufficient to make a diagnosis

of laryngomalacia or viral croup, additional diagnostic tests are warranted for patients whose

symptoms and clinical course seem unusual or overly severe.

Laboratory testing has limited value in evaluating patients with stridor. Similarly, pulmonary

function testing is not often necessary but can confirm suspicions of an extrathoracic

obstruction

Objective Testing

A simple radiograph of the neck can identify obstructive lesions in the retropharynx, glottis,

and subglottic area (Next Figure).

The classic steeple sign on anteroposterior neck radiograph depicts subglottic narrowing but

does not distinguish croup from subglottic stenosis.

Direct visualization of the airway by flexible laryngoscopy often provides definitive

information.

Objective Testing ….. Flexible laryngoscopy

Is a routine procedure for the practicing otolaryngologist. Because the procedure offers direct visualization of the posterior pharynx and glottis, numerous other lesions causing laryngeal obstruction can be visualized, leading to a correct diagnosis.

In fact, before routine use of office-based flexible laryngoscopy, laryngomalacia was known as congenital laryngeal stridor..

The procedure is usually well tolerated and can be performed most often with topical anesthesia alone .

In many instances, laryngoscopy merely confirms the presence of laryngomalacia while excluding other causes of airway obstruction.

Objective Testing

In cases of severe laryngomalacia, laryngoscopy can also identify specific structures of the

larynx that are causing obstruction that might be amenable to surgical correction .

Of course, direct visualization of the glottis can also identify other lesions that cause

obstruction.

Successful flexible laryngoscopy is often dependent on patient cooperation, particularly with

anxious, difficult-to-restrain, and younger school-aged children.

Objective Testing

laryngoscopy often provides a clear view of the glottis and supraglottic structures, the

subglottic area cannot be well visualized. Indeed, even with a cooperative patient, the presence

of severe laryngomalacia might obscure the view of the subglottic area such that a more distal

lesion would not be visible.

Direct visualization of the subglottic region and proximal trachea may be indicated to exclude a

second lesion.

Direct laryngoscopy and bronchoscopy under sedation or general anesthesia can help diagnose

and quantify the severity of subglottic stenosis or identify other subglottic lesions that cause

obstruction .

MANAGEMENT

laryngomalacia and viral croup are frequently encountered and will include most patients with stridor, the general pediatrician should be comfortable with outpatient management.

Most cases of laryngomalacia can be managed with observation alone, with particular attention given to adequate caloric intake and weight gain.

For patients with severe episodes of stridor causing hypoxemia or cyanosis, or if symptoms progress over time, additional diagnostic testing is indicated, and referral to a subspecialist may be warranted

MANAGEMENT

laryngomalacia requires surgical management to relieve the obstruction caused by redundant

epiglottic folds or arytenoid tissue.

Tracheostomy is rarely required.

As with laryngomalacia, most patients with viral croup can be managed with close observation

alone.

For children with more severe obstruction (nasal flaring, retractions), racemic epinephrine and

dexamethasone may temporarily relieve symptoms of obstruction and alleviate inflammation,

respectively.

MANAGEMENT

Hospitalization is indicated for children with:

Hypoxemia, apnea, or poor feeding or dehydration. Continuous, progressive, or severe stridor

should prompt the pediatrician to initiate additional diagnostic tests.

Laser therapy for a hemangioma or web can provide definitive cure, as can cricoid split and

augmentation of the subglottic space for an acquired stenosis.

When to Refer

• Progressive or continuous stridor

• Poor weight gain or growth associated with persistent stridor

• Repeated hospitalization

• Presence of cutaneous hemangiomas in association with persistent stridor

When to Admit

• Respiratory distress or hypoxemia

• Inability to eat or drink

• Altered mental status or signs of fatigue

• Stridor associated with signs of increased intracranial pressure

Summary

The pediatrician evaluating the child with stridor should be aware of the various clinical entities

that can present with stridor, be able to recognize by history or physical examination patients

who require further evaluation, initiate simple diagnostic tests, and refer to appropriate

subspecialty physicians those children with unusual presentations or poor response to

conventional therapies.

CHIEF COMPLAINT

Mr. S is a 15-year-old boy who arrives at the emergency department with sore throat, fever, and

wheezing. He reports being well until 2 days ago when his sore throat started. Over the next 2

days, the sore throat became progressively more severe and he lost his voice. On the morning

of admission, a fever of 38.0°C and wheezing developed. He was also unable to eat because of

the pain. He has never had similar symptoms before.

At this point, what is the leading hypothesis, what are the active alternatives, and is there a must

not miss diagnosis? Given this differential diagnosis, what tests should be ordered?

PRIORITIZING THE DIFFERENTIAL

DIAGNOSIS

The pivotal points in Mr. S’ presentation are the acuity of the illness and the fever.

Both of these points make an infectious etiology likely.

Because the symptoms are not recurrent, asthma, the most common cause of airway

obstruction, is unlikely.

PRIORITIZING THE DIFFERENTIAL

DIAGNOSIS

Acute infectious causes need to be considered first

These include common conditions, such as pharyngitis, and rare but serious causes, such as epiglottitis and retropharyngeal abscess.

Angioedema is a possibility, but the infectious symptoms (fever and pain) and the lack of visible swelling make this less likely.

Aspiration of a foreign body could cause either a pneumonia or infection of the soft tissues of the neck resulting in fever. Next table lists the differential diagnosis.

Is the clinical information sufficient to make a diagnosis? If

not, what other information do you need?

The patient’s physical exam makes pharyngitis a less likely cause of his symptoms. His pharynx

is patent, and there is more distal stridor.

Leading Hypothesis:Epiglottitis

Fever and sore throat are usually the presenting symptoms.

There can be evidence of varying degrees of airway obstruction including wheezing, stridor,

and drooling.

The disease has become significantly less common in children since the use of the

Haemophilus influenzae B vaccine.

Epiglottitis : Disease Highlights

A. Epiglottitis is an infectious disease, classically caused by H influenzae, that causes swelling of

the epiglottis and supraglottic structures.

B. Can rapidly cause airway compromise so the diagnosis is always considered an airway

emergency.

C. Classic presentation is a patient with sore throat, muffled “hot potato” voice, drooling, and

stridor.

D. H influenzae is cultured in only a small percentage of adult patients; respiratory viruses are the

likely cause of most cases of epiglottitis.

E. Epiglottitis is a difficult diagnosis because initial presentation is often identical to pharyngitis.

Epiglottitis : Evidence-Based Diagnosis

The gold standard for diagnosis is visual identification of swelling of the epiglottis.

1. Otolaryngology consultation is thus mandatory in any patient with a high suspicion for the

disease.

2. Visualization can be achieved with direct or indirect laryngoscopy.

3. In patients with signs of severe disease (eg, muffled voice, drooling, and stridor), an

experienced physician should perform direct laryngoscopy and be prepared to intubate the

patient or perform a tracheostomy (if airway control cannot be obtained).

Epiglottitis : Evidence-Based Diagnosis

The classic symptoms of muffled voice, drooling, and stridor are seen very rarely and signify

imminent airway obstruction.

1. Sitting erect and stridor are independent predictors of subsequent airway intervention

(RRs of 4.8 and 6.2, respectively).

2. In 1 study of patients with epiglottitis, the test characteristics of sitting erect at

presentation and stridor were as follows:

a. Sitting erect at presentation: Sensitivity, 47%; specificity, 90%; LR+, 4.7; LR−. 0.59.

b. Stridor: Sensitivity, 42%; specificity, 94%; LR+, 7; LR−, 0.61.

Epiglottitis : Evidence-Based Diagnosis

Common symptoms and signs of patients with epiglottitis are shown in the Next table.

Lateral neck films, a commonly used diagnostic tool, have a sensitivity of about 90%. The

classic finding is the “thumb sign” of a swollen epiglottis.

A normal lateral neck film does not rule out epiglottitis.

Laryngoscopy should be performed in a patient with a high

clinical suspicion of epiglottitis, even if the neck film is

normal

Epiglottitis :Treatment

Airway control

1. All patients should be admitted to the ICU for close monitoring.

2. Patients with signs or symptoms of airway obstruction should be intubated electively.

3. Elective intubation is preferred because intubation in a patient with epiglottitis can be very

difficult.

4. Some advocate prophylactic intubation of all patients.

Epiglottitis is an airway emergency. Patients need to be

monitored extremely closely and not left alone until the

airway is stable. Otolaryngology consultation is mandatory.

Epiglottitis :Treatment

Antibiotics

1. Necessary to cover H influenzae.

2. Second- or third-generation cephalosporins are usually recommended

Epiglottitis :MAKING A DIAGNOSIS

Mr. S’s history is very concerning. His upright posture, voice changes, and stridor are not only

indicative of epiglottitis but also of imminent airway closure.

None of these findings would be seen with pharyngitis. Foreign-body aspiration does not fit

the history.

Retropharyngeal abscess remains a possibility.

Alternative Diagnosis: Retropharyngeal Abscess

Retropharyngeal abscess can be seen in either children or adults. Patients usually have

symptoms similar to those seen in epiglottitis but commonly have a history of a recent upper

respiratory infection or trauma from recently ingested materials (bones), or procedures

(pulmonary or GI endoscopy).

Retropharyngeal Abscess: Disease Highlights

Symptoms that suggest retropharyngeal abscess rather than epiglottitis are:

1. Patients with retropharyngeal abscesses often will sense a lump in their throat.

2. Patients are often most comfortable supine with neck extended (very different from

epiglottitis).

Retropharyngeal Abscess : Evidence-Based

Diagnosis

The diagnosis of retropharyngeal abscess is made when a thickening of the retropharyngeal

tissues is seen on lateral neck radiographs.

Radiographs are probably not 100% sensitive, so when radiographs are normal and clinical

suspicion is high, CT scanning should be done to verify the diagnosis.

Retropharyngeal Abscess : Treatment

Retropharyngeal abscesses are usually polymicrobial.

Treatment is both medical and surgical.

1. Surgical drainage should be accomplished as soon as possible.

2. Many antibiotics have been suggested. Coverage of grampositive organisms and anaerobes

make clindamycin a common choice.

The patient’s infection was diagnosed on the lateral neck

radiographs. Intubation was necessary because the patient

had signs and symptoms of airway obstruction and the

actual obstruction was visualized on laryngoscopy.

References

Signs and Symptoms in Pediatrics-American Academy of Pediatrics

Symptom to Diagnosis_ An Evidence Based Guide-McGraw-Hill Medical (2009)

The Patient History_ An Evidence-Based Approach to Differential Diagnosis-McGraw-Hill

Medical (2012)