Approach to stridor in a Approach to stridor in a 6 year old child6 year old child

Jacques le Roux24/08/2012

APPROACH TO STRIDOR IN 6 YEAR OLD CHILD

• Anatomy (upper airways)

• General reminders

• Etiology

• Approach- Imaging options- Imaging findings

ANATOMY

1. Supraglottic Region – above vocal cords•Epiglottis with•Aryepiglottic folds (runs laterally and convex-INF)

2. Glottic •Level of true vocal cords (triangular space)•Level of thyroid cartilage

3. Subglottic •Trachea starts here•Level of cricoid cartilage

Trachea on:- frontal X-Ray, convex shoulders- axial imaging, round (if not pathology)

•Thoracic inlet: Line through sternal angle / T4

- Above is upper airway- Below starts lower airway

•Retrophareng. (prevert soft tissue)- From C1 – C4 : normal ¾ of vertebral body- Lat must be taken in extension (flexion makes it wider)

GENERAL REMINDERS (CAUSES OF AIRWAY OBSTRUCTION IN A CHILD)

CLASSICAL

• < 3 years - croup (subglottic laringo-tracheo bronchitis) - not life-threatenig (self limited disease)

• Life-threatening- Infant – choanal atresia- 3-6 years – epiglottitis- Any age - foreign bodies (also in esoph)

- 80% radiolucent- Angioneurotic edema

• ± 6 years - other causes - think: upper or lower airways and intrinsic or extrinsic causes

ETIOLOGYUPPER AIRWAYS- Above thoracic inlet-Inspiratory stridor-Usually acute (infective)

ACUTE1. Foreign bodies2. Retropharengeal - Cellulitis - Abscess (gas)3. Quinsy (tonsils)4. Lymphadenitis

- BACT- TB (scrofula)

5. Exudative tracheitis6. Angioedema

CHRONIC1. Enlarged tonsils (adenoid, palatine, lingual)2. Large tongue (Down)

LOWER AIRWAYS- Below thoracic inlet-Inspiratory stridor and expiratory wheeze (some also call it stridor)-More chronic-Some asymptomatic

-Intrinsic/Extrinsic

INTRINSIC1. Foreign bodies2. Post intubation stricture /granuloma3. Hemangioma (most common mass in trachea)

- Subglottic (Ass with facial hemangiomas)

LOWER AIRWAY OBSTRUCTIONEXTRINSIC – think ant. and middle mediastinumA. ANT – the 4 T’s

Normal thymus - large until 6 years - never compresses airways / vessels - ABN one does – look for Ca⁺⁺

1. Lymphoma (“terrible”) - most common ant. mass (older child) - look for other nodes

2. Thymic masses (cyst – AIDS, thymomas – rare)3. Teratoma - Ca⁺ and fat4. Thyroid tumors – rare

B. MIDDLE1. Nodes (lymphoma, TB, METS) – most common mass2. Duplication cysts

(a) bronchogenic, ass with carina(b) enteric – ass with GIT

3. Vascular – rings - encircle esoph. and trachea Pulmon. sling – between trachea and esoph.4. ↑ L Atrium

C. POST - Rare cause Neurogenic tumors

•Ganglioneuroblastoma and ganglioneuroma (6 years)•Neuroblastoma (classic < 2 years)

IMAGING OPTIONS

A. CHOICEFrontal and lat. neck and CXR

B. BACK-UP -Δ various intrins and extrins lesions

1. CT (better than MRI) • faster, seldom sedation• Risk - radiation, CT (10mSv)

MDCT (20-30mSv) - contrast reactions• options - multiplanar, 3D volume rendered

- vascular rings, sling - abscess : cellulitis - metallic for. bodies

2. Upper GI series - vascular rings, sling

3. Sonar : Ant. mediast. - ABN thymus (heterog Ca⁺⁺, fat) - biopsy + local is choice - if trachea > 50% narrow and with general – expect problems

FOREIGN BODIES and IMAGING

• 80% RADIOLUCENT (look for indirect signs)

1. Fluoroscopy (Dynamic)• Mediast. shifts away from obstruc. with expiration (airtrapping)

2. Lat. Decubitus• Normal: Dependent side hypo-aerated

with FB stays hyper-aerated 3. EXP CXR - airtrapping (radiolucent) - flat diaph. (normal inspiration R 6 rib – L 2cm lower) • 20% RADIO OPAQUE eg coin – lateral XR

• In airways - perpendicular (round) to projection• In esoph. - parallel (slim-like, pancake)

• Bronchoscopy Δ and treatment

IMAGING FINDINGSUPPER AIRWAYS – ACUTE/CHRONIC

TWO REMINDERS - < 6 Years

Normal – subglottic airway shows rounded shoulders

1. Croup• Loss of shoulders• Steeple sign

Subgottic narrowing

Epiglottis normal

2. EPIGLOTTITIS• Thick epiglottis• Thumb sign

Thick epiglottis and aryepiglottic fold

EXUDATIVE TRACHEITIS - 6 – 10 Years - Staph

• Trachea walls irregular• Normal epiglottis

RETROPHARENGEAL CELLULITISA.• Retrofar. soft tissue swelling• More than vertebral body

B and C : CT with contrast• Low att. Mass• No rim enhancement

• Difficult to do Δ Δ from abscess – clue is gas [ cellulitis no gas ]

RETROPHARENGEAL ABSCESS

A. Retrophareng – thick soft tissue B. CT with contrast

- Low att. mass- Rim enhancement

PSEUDORETROPHARENGEAL SOFT TISSUE THICKENING

A. Lat - thick retrophar soft tissue - image in flexion

B. Lat - no thickening - image in extension ( is the way)

TB (SCROFULA) – TB glands

CT WITH CONTRAST• Bilat. necrotic lymph adenopathy• Usually no pulm TB

TONSILS

Adenoid and palatine enlarged tonsils

T2 with fat saturation

Enlarged lingual tonsisls- T2 high

[Normal signalTonsils same as muscles of tongue]

ADENOID TONSILS

A. Enlarged

T₂ Gradient echo (cine)

B. Expiration• Airway open

C. Inspiration• Collapse of airway

Adenoid tonsils (T₂ with fat saturation – tonsil ↑ signal)• removed gives a V shaped appearance• absent at birth• Reach max size 2 – 10 years• After removal – commonly grows back

Ass with collapse of laringopharynx (stridor) with inspiration, because sup. obstruction cause negative pressure in laringopharynx

Bilat. palatine tonsils enlarged

- kissing tonsils- obstruction of airway

PERITONSILLAR ABSCESS

CT WITH CONTRAST• ↓ Att• Rim enhance

ANGIOEDEMA

• Diffuse edema around trachea (↓Att)• Pat. was on ACE-inhibitor for high BP

GLOSSOPTOSIS – eg Down

Obstruction of airway

LOWER AIRWAYS

EXTRINSIC

NORMAL THYMUS

Infant – passed away - prominent size

Normal “sail” sign

CT• Quadrilat. in shape• Homogeneous att.• No compression of trachea or SVC

BRONCHOGENIC CYST - COMPRESSING LEFT MAIN BRONCHUS

- 50% of intrathoracic cysts- Most asymptomatic- Location - Carina (most common) - Paratracheal (usually right) - Hila

B. - Low att. Mass - Adjacent to carina - compressing L main bronchus

A. LLL - Retrocardiac density - Asim. aeration of lungs

LYMPHOMA – MOST COMMON ANT. MEDIAST. MASS IN CHILD

A - Wide mediast.

B and C - Trachea post displaced and compressed

C and D - SVC encased and compressed

VASCULAR RINGS/SLING

• Some not found in 6 years• Some will not compress airways

NORMAL ANATOMYLevel T₃ 9 : Trachea10 : Esophagus6,7 : R, L CCA5,8 : R, L SCA

Innominate art.(Br. ceph. truncus) - from right - passes just in front of trachea just inf. to level of thoracic inlet

Level T₄

4 : SVC3 : normal L aortic arch.

VASCULAR ABNORM. ( RINGS AND PULM. SLING)DIAGRAMS COMPARED WITH LAT. CXR / FLUOROSCOPY

1. Double aortic arch

• Most common• Δ after birth• Both trachea and esoph. compressed• Both join desc. Aorta - additional compression in midline

2. Pulm. Sling• Only vasc abn that passes between esoph and trachea• L PA comes from R PA• Compress both (tracea/esoph)

3. Innominate art compression syndrome• Origin more to left and with large thymus, cause compression just below thoracic inlet• Highest vasc. abn

4. R Arch with aberrant L SCA

Meg of airway compression• Kommerell diverticulum - dilation of aorta where L SCA starts• Lig. arteriosum completes ring as well• More midline desc. aorta

5. L Arch with aberrant R SCA

DOUBLE AORTIC ARCH

Ba ⁺⁺ study: (Reverse S-shaped esoph.)• Bilateral extrinsic compressions on the esoph.

CT• Compress trachea ant.

R AORTIC ARCH WITH ABERRANT L SCA

Ba⁺⁺ study: post compression of esoph.

A. CXR (AP) – clue of R arch - no knob L seen - trachea to leftB. CXR (Lat) – trachea ant. and compressedC. CT – R aortic arch with aberrant L SCAD. Midline desc. Aorta causes compression

PULM. SLING

CT• L PA comes from R PA instead of MPA• Only vasc. abn that passes between esoph. and trachea

CXR • Above named cause compression of trachea and R main Bronchus – reason that aeration is less in R lung

INNOMINATE ART. COMPRESSION SYNDROME

• Compresses the trachea – if trachea not round there is extrins. compression

FOREIGN BODIESMore common in R main bronchus than upper airways

NON OPAQUE (80%)

INDIRECT SIGNSCXR PA – expiratory• L lung hyperlucent due to airtrapping • Normal dependent side will hypoaerate

Lat. decubitus• L lung will stay aerated

RADIO-OPAQUE (20%)• Button in subglottic area (round)• Bronchoscopy for removal

RADIO-OPAQUE FB IN ESOPHAGUS vs TRACHEA

CXR LAT

• In esoph. – foreign body present - appears slim (like a pancake)

• In trachea – perpendicular (round)

POST INTUBATION STRICTURE AND GRANULOMA

SUMMARY

ETIOLOGY : STRIDOR IN 6 YEAR OLD

UPPER AIRWAYS LOWER AIRWAYS

Foreign bodiesInfections

ACUTE

CHRONICEnlarged tonsils

INTRINSICForeign bodies

EXTRINSIC – think ant. and middle mediastinumA. ANT – the T’sLymphoma (“terrible”) - most common ant. mass (older child)B. MIDDLENodes (lymphoma, TB, METS) – most common massC. POST – Neurogenic tumors Rare cause

It has been said that one of the differentiating features between a pediatric and a general radiologist is that a pediatric radiologist remembers to look at the airway.

Problems with the airway are much more common in children than in adults.

References

1. Yedururi S, Multimodality Imaging Of Tracheo Bronchial Disorders In Children Radiographics May 2008.2. Berrocal T, Cong. Anomalies Of Tracheobronchal Tree And Mediatinum: Radiology And Pathology Radiographics Nov. 2003.3. Ludwig B, Diagnostic Imaging In Nontraumatic Pediatric Head And Neck Emergencies, Radiographic 2010; 30: 781-799.4. Capps E, Emergency Imaging Assessment Of Acute Non Traumatic Conditions Of The Head And Neck Radiographics 2010; 30: 1335-1352.5. Gooding CA, Essentials Of Pediatric Radiology Cambridge 2010, 40-74.