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Onset, sounds help pinpoint cause of stridor: pay careful attention to the details when parents describe how the illness developed, an expert urges.

STANFORD, CALIF. -- Be a good listener to distinguish the cause of stridor in children, Dr. Anna H. Messner stressed at a recent pediatric update sponsored by Stanford University.

Tuning in to the pattern and the tone of a child's noisy breathing will certainly help clinch the diagnosis, but it's also important to pay careful attention to the details when parents describe how the illness developed.

"Whenever you're trying to figure out what a kid has, you want to try and classify stridor in your mind," said Dr. Messner of the departments of pediatrics and otolaryngology/head and neck surgery at the university.

First, decide whether the audible part of the child's breathing is inspiratory, expiratory, or both (biphasic).

"Sometimes I make my own chest go in synch with the kid to see which it is," she suggested.

Inspiratory stridor points to a lesion at or above the vocal cords. Examples of inspiratory stridor include epiglottitis (supraglottitis), laryngomalacia, and bacterial tracheitis.

Audible expiratory breathing, or wheezing, suggests a narrowing of the trachea or the bronchus.

Biphasic stridor suggests involvement at or below the vocal cords, as in the case of croup, in which an obvious audible inspiratory component may be paired with an expiratory barking cough.

Vocal cord paralysis may present with inspiratory stridor, but may have an expiratory component as well.

Other clues are also important when considering the various conditions underlying stridor:

* Croup (laryngotracheitis). It is highly likely to be preceded by nasal congestion and/or a discharge in a baby 6-36 months old. Fever may be present, but the onset is gradual. On x-ray, look for the "steeple sign" indicating swelling of the subglottis.

"It would be really unusual to see croup without a nasal discharge," said Dr. Messner.

* Epiglottitis (supraglottitis). This disease, on the other hand, was historically known for its extremely rapid onset, she explained. "It's not the kid who's had a cold for a few days. This was the kid who was active, playing, healthy in the morning and was sick as a dog in the afternoon."

Symptoms include fever, sore throat, and drooling, but most telling is the child's behavior and posture. Often, they lean forward at an awkward angle.

"When you see these kids, what you notice is, they won't move. They don't lie down if they can help it. If they're moving around, they do not have epiglottitis," Dr. Messner commented. Widespread vaccination against Haemophilus influenzae type b (Hib) beginning in 1991 sharply reduced the number of epiglottitis cases in the United States from 100 per 100,000 to 0.3 per 100,000.

Today, epiglottifis is seen rarely, mostly in children who failed to respond to the vaccine and in those infected with influenza type A, Streptococcus pneumoniae, and Staphylococcus aureus.

More worrisome is the population of immigrant children who have never received the Hib vaccine, and could well show up with symptoms of a disease that is becoming less recognizable to pediatricians.

"That's why we need to know a lot about it." Urgent action is required with epiglottitis, she emphasized. "They all get intubated. You don't wait for respiratory distress, because often that's too late."

* Bacterial tracheitis. This may be a primary infection, but is more often a complication of croup, according to Dr. Messner.

Typically, babies become markedly worse 2-3 days into croup, developing a high fever and appearing in distress. The cause is an obstruction and secondary infection of the trachea with thick, purulent exudate.

The majority of children present with cough, retractions, and stridor, whereas hoarseness is somewhat less common.

"These kids are sick," Dr. Messner said, noting complications such as respiratory distress syndrome, subglottic stenosis, and pulmonary edema.

Because S. aureus is the organism most often responsible for bacterial tracheitis, there has been some concern that an uptick in cases will be seen as a result of widespread outbreaks of methicillin-resistant S. aureus (MRSA).

It's possible, said Dr. Messner, but "I don't think we've seen it yet."

* Laryngomalacia. This is the most common cause of stridor in newborns. This disorder of immature laryngeal and pharyngeal tone is noteworthy for its distinctive low-pitched, coarse cry

"Some people have described it as a turkey gobble," said Dr. Messner.

Laryngomalacia stridor is strictly inspiratory, and generally intermittent, worse during feeding and sleeping, but abating during crying.

Importantly, laryngomalacia can be diagnosed and evaluated by an otolaryngologist using a flexible laryngoscope in the clinic.

"If you are working with an ENT who says, 'Oh, I have to take all of these kids to the operating room," you probably want to find another ENT ... because there is no reason for these kids to go under anesthesia to check out their larynx," Dr. Messner commented. "There are some very good ENTs that work with kids a fair amount, and there are also some who shouldn't go near children," she added.

Bronchoscopy is usually not necessary for laryngomalacia.

Babies often recover without treatment when they are aged between 12 and 18 months; until then, pediatricians should monitor weight, be alert to feeding difficulties such as choking and aspiration, and consider treating their gastroesophageal reflux disease, which affects virtually 100% of children with laryngomalacia.

In babies who fail to thrive and do poorly, supraglottoplasty surgery may be considered to remove tissue from around the larynx and improve feeding issues.

RELATED ARTICLE: Tone reveals vocal cord paralysis.

Stridor resulting from vocal cord paralysis is most recognizable by its tone, which is high-pitched and musical, said Dr. Messner.

The child's breathing sounds may be biphasic--mostly inspiratory, but possibly with an expiratory component.

Vocal cord paralysis should be high on the differential diagnosis list in any stridulous child with a significant medical history in the newborn period, because prolonged intubation is a risk factor, as is cardiac surgery, particularly patent ductus arteriosus ligation and aortic reconstruction, which can stretch or damage the recurrent laryngeal nerve.

Sometimes, vocal cord paralysis results from birth trauma, even in a healthy infant, or is idiopathic, said Dr. Messner.

If the paralysis is unilateral, pediatric patients are generally followed by observation, with careful attention to proper weight gain and possible consultation with an occupational therapist if feeding or choking problems raise a concern about aspiration.

"Those kids actually do quite well. They might have a little bit of weak voice," she said, noting that the vocal cord may heal or the other vocal cord may compensate over time. "I tell the parents, they're not going to be an opera singer, but maybe a country western singer."

On the other hand, bilateral vocal cord paralysis resulting from underlying nerve dysfunction, or vocal cord fixation resulting from joint immobility, may cause airway obstruction, often requiring a tracheotomy.

Although the procedure is frightening to parents, Dr. Messner noted that "kids with tracheotomies can do absolutely everything kids without trachs can do, except they can't swim which of course they all want to do--and they can't be in the care of someone who doesn't know anything about trachs."

The major dangers associated with tracheotomies are plugs of mucus, which must be suctioned by a trained individual, or decannulation by "'an inquisitive toddler."

Either way, a catastrophe can be avoided if someone is immediately able to clear or replace the tracheotomy tube.

"You've got to do it quick, otherwise that baby will die," she warned.

Dr. Messner said she knows of six children who have died because of tracheotomy complications, which is in line with the U.S. mortality rate of 3%-5%.

"For us to send a kid home with a trach is a big deal," she said. Families need to understand the absolute necessity of 24-hour observation.

Surgical options also are available to correct bilateral vocal cord paralysis/fixation, but the success rates are variable.

"There are tons of ways to fix this ... which means none of them are that good," she said.


Los Angeles Bureau
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Title Annotation:Clinical Rounds
Author:Bates, Betsy
Publication:Pediatric News
Geographic Code:1USA
Date:Dec 1, 2007
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