We proposed a workflow  for interpretating non traumatic head and neck emergencies which commonly present in the paediatric population, using examples for our institution. Fig. 1

Fig. 1: Proposed workflow for dealing with paediatric non traumatic head and neck emergencies

Ocular Abnormalities:

Periorbital cellulitis is distinguished from orbital cellulitis by their location in respect to the orbital septum Fig. 2 . The orbital septum is a fibrous sheet which is continuous with the orbital rim periosteum and blends with the tendon of the levator palebrae superioris superiorly and inserts inferiorly into the tarsal plate. This anatomical landmark allows accurate diagnosis and aggressive management in the setting of orbital cellulitis.

Fig. 2: Blue line demonstrates the expected course of the orbital septum.

Periorbital Cellulitis:

Periorbital/Preseptal cellulitis involves preseptal soft tissues anterior to orbital septum and usually occurs secondary to facial or odontogenic infection.

Fig. 3: Periorbital cellulitis in a 6 year old boy with eyelid swelling. Axial contrast enhanced CT image demonstrates preseptal soft tissue swelling overlying the right eye.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Clinical Presentation

• Eyelid swelling
• Eyelid erythema and chemosis
• NO PROPTOSIS

Imaging Findings:

• Usually contrast enhanced CT due to availability in emergency setting but similar findings on MRI.
• Inflammation and induration of soft tissues anterior to orbital septum.

Orbital Cellulitis:

Orbital Cellulitis involves the postseptal soft tissues which include intraconal space (space within the extraocular muscles); extraconal space (space outside extraocular muscles between orbital bone) and subperiosteal tissues. Orbital cellulitis commonly occurs secondary to sinusitis.

Clinical Presentation

• Eyelid swelling
• Eyelid erythema and chemosis
• Eye movement and pupil abnormalities
• +/- PROPTOSIS

Imaging Findings:

• Usually contrast enhanced CT due to availability in emergancy setting but similar findings on MRI.
• Retrobulbar stranding
• Sinus opacification
• Extraconal/subperiosteal abscesses with mass effect on extraocular muscles

**Early abscesses may not demonstrate peripheral enhancement**

Complications:

• Cavernous sinus and superior ophthalmic vein thrombosis
• Meningitis
• Intraconal abscess
• Intracranial abscesses

Fig. 4: Orbital cellulitis with subperiosteal abscess in a 11 year old girl with eyelid swelling and ophthalmoplegia. (a) Axial contrast-enhanced CT image shows a peripherally enhancing abscess within the left superior extraconal/subperiosteal space, better seen on corresponding saggital image (b). Corresponding ethmoid and maxillary opacification noted.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Fig. 5: Complications of left orbital cellulitis in a 8 year old boy. (a) Axial contrast-enhanced CT image demonstrates large indistinct superior ophthalmic vein (arrow) consistent with thrombosis. (b) Coronal MR venogram shows low signal in both cavernous sinuses consistent with thrombus.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Fig. 6: Complications of orbital cellulitis (a) Axial contrast-enhanced CT image depicts enhancing extraaxial collection overlying the inferior aspect of the left frontal lobe. (b) Corresponding axial MR diffusion imaging demonstrating restriction and (c) axial post gadolinium MRI brain demonstrating enhancing lesion. Imaging features consistent with subdural collection.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Mimics

• Orbital pseudotumour
• Langerhans Cell Histiocytosis
• Intra/extraorbital neoplasms: Neuroblastoma metastatic lesion, Acute myeloid leukaemia, rhabdomyosarcoma.

Fig. 7: Axial contrast enhanced CT orbits demonstrating orbital mimics. (a) Metastatic lesion from neuroblastoma (b) Acute myeloid leukaemia (c) Langerhans Cell Histiocytosis (d) Well circumscribed lesion within the medial canthus, confirmed on histology as rhadomyosarcoma
References: Department of Radiology, OLCHC, Dublin/IE 2016

Dacryocystitis:

Inflammation and dilatation of the lacrimal sac (medial canthus), which occurs secondary to obstruction of the nasolacrimal duct.

Fig. 8: Dacrocystitis in a 7 month old with right eye swelling. Axial contrast enhanced CT image demonstrating preseptal swelling of the right eye with peripherally enhancing, hypodense collection at the level of the lacrimal sac.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Clinical Presentation

• Medial canthus swelling
• Lid swelling
• Conjunctivitis

Mimics Fig. 7:

• Inflammatory conditions: Sarcoid
• Mucocoele
• Epidermoid cyst
• Malignancy: lymphoma/squamous cell carcinoma/rhabdomyosarcoma.

Paranasal Sinus Abnormalities:

The maxillary sinuses are the first sinuses to pneumatise occuring approximately 70 days post birth, followed by ethmoid, sphenoid and frontal sinuses. Pneumatisation is usually complete by 5-7 years.

Acute sinusitis:

Acute sinusitis is a clinical diagnosis with patients presenting with cold symptoms and purulent nasal discharge. CT/MRI findings of mucosal thickening and sinus opacification are non specific, often seen incidentally on imaging and imaging features do not correlate well with disease severity. Thus imaging is not recommended in acute uncomplicated sinusitis.

The main role of imaging is to identify sinus related complications.

Complications:

• Orbital cellulitis
• Osteomyelitis
• Potts Puffy Tumour
• Extraaxial empyema
• Intracranial abscess
• Meningitis

Potts Puffy Tumour:

Potts Puffy Tumour occurs from frontal sinusitis which leads to thrombophlebitis within valveless emissary veins leading to

• Frontal subperiosteal abcess
• Necrosis of the inner and outer table of frontal bone

Fig. 9: Potts puffy tumour in a 15 year old boy with headache and frontal swelling. (a) Axial contrast enhanced CT brain show a peripherally enhancing subgalaeal collection overlying the left frontal lobe with peripherally enhancing extraaxial collection (arrow). (b) Axial CT brain on bone windows demonstrates associated necrosis of the inner and outer table of the frontal bone.

Complications:

• Cavernous sinus thrombosis
• Venous infarction
• Extraaxial abscess
• Intracranial abscess

Temporal Bone Abnormalities:

Acute otitis media, middle ear inflammation, is predominantly a clinical diagnosis with the role of imaging in diagnosis of complications, most notably acute mastoiditis. CT temporal bones is crucial for accurate diagnosis.

Fig. 10: 16 year old girl with clinically bilateral otitis media. Axial contrast enhanced image of temporal bones demonstrates bilateral otitis externa and media with opacification and enhancement of the mastoid air cells compatible with acute bilateral mastoiditis.

Complications of mastoiditis:

• Petrous apicitis: Spread of infection into pneumatised petrous apices
• Labyrinthitis
• Facial nerve palsies
• Meningitis
• Epidural abscess*
• Dural sinus venous thrombosis

* Intracranial complications occur more commonly in coalescent mastoiditis, mastoiditis with erosion of mastoid septa/cortex with periosteal reaction*

Fig. 11: Complications of acute mastoiditis. (a) Axial contrast enhanced CT brain shows ring enhancing lesion within the left parietal lobe with associated mass effect. Prior craniotomy noted. (b)Axial contrast enhanced CT brain shows extraaxial collection overlying the right temporal lobe (c) Axial contrast enhanced CT brain shows right temporal intracranial abscess.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Fig. 12: Complications of acute mastoiditis. (a) Axial contrast enhanced CT brain shows peripheral enhancing collection superior to right mastoid air cells, consistent with abscess with small extraaxial collection also demostrated. (b) Coronal MR venogram in the same patient demonstrates a filling defect within the right transverse sinus (arrow) consistent with thrombosis.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Mimics of Mastoid Pathology:

• Langerhans cell histiocytosis
• Rhabdomyosarcoma
• Metastatic disease, typically neuroblastoma

Mimics usually have bony destruction with cranial nerve pathology more commonly occuring in malignant processes.

Airway Abnormalities:

Apiration or ingestion of Foreign Bodies commonly occurs in children aged 1-3 years old.

1. Aspiration

• Small items such as seeds or beans.
• Lodged in right main bronchus, less commonly in upper airway.
• Paroxysmal cough +/- respiratory distress
• If clinically stable: AP and lateral neck radiograph, frontal chest radiograph BUT 80% foreign bodies are radiolucuent
• Secondary signs of ingested foreign body: hyperinflation indicative of air trapping

Fig. 13: 3 year with paroxysmal cough and history of ingested foreign body. Frontal chest radiograph shows hyperinflation of the left lung indicative of air trapping, a secondary sign of foreign body inhalation.
References: Department of Radiology, OLCHC, Dublin/IE 2016

      2. Ingestion

• Coins, toys, food.
• Lodged in the oesophagus, commonly at cricopharyngeal muscles/level of the aortic arch/lower oesophagheal sphincter/underlying abnormality e.g. vascular ring or stricture.
• AP and lateral neck radiograph and frontal chest radiograph.

Fig. 14: Ingested Foreign Body: Frontal chest radiograph and lateral neck radiograph show ingested coin at the thoracic inlet.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Tonsillar disease:

Acute tonsillitis is a common childhood illness with diagnosis made on clinical history and examination.

Clinical presentation:

• Fever
• Sore throat
• Dysphasia
• +/- Trismus

The role of imaging is to differentiate complication of peritonsillar abscess from tonsillitis.

Imaging findings of peritonsillar abscess on Contrast enhanced CT:

• Diffuse enlargement and enhancement of tonsil
• Associated fluid collection with peripheral enhancement
• +/- mass effect on oropharynx

Fig. 15: Peritonsillar abscess. (a) Axial contrast enhanced CT neck shows peripherally enhancing collection in the left peritonsillar region. (b)xial contrast enhanced CT neck shows peripherally enhancing collection in the left peritonsillar region with mass effect on the oropharynx and associated bilateral tonsillar enlargement.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Mimics:

• Necrotic retropharyngeal lymph node
• Lymphoid hyperplasia

Epiglottis:

• Aged 1-5 years old
• Clinical diagnosis: Fever, sore throat, drooling, posturing
• Haemophilius influenzae: RARE Vaccination programmes have reduced rates from past, however incidence increasing last number of years.
• High risk of airway compromise.
• Imaging not recommended: Lateral radiograph of neck: Thumb sign Fig. 16
  

Laryngotracheobronchititis: Fig. 17

• Croup
• Aged 6months- 3years old
• Viral: parainfluenzae
• Clinical presentation: Viral prodrome, fever, inspiratory stridor
• Role of imaging: Identify other causes of inspiratory stridor, e.g. foreign body

Neck Abnormalities:

Cervical Lymphadenopathy:
Enlarged lymph nodes is a common presentation of a neck mass and can occur due infectious, inflammatory, neoplastic or idiopathic processes.

Imaging findings:

• Enlargement: >10mm short axis
• Rim enhancement of contrast enhanced CT: supporative nodes

Congenital Cystic lesions such as thyroglossal duct cysts and branchial cleft cysts can often present to emergency department with complication such as superinfection.

Thyroglossal duct cyst:

• Failure of involution of the thyroglossal duct
• Can occur anywhere between foramen caecum at base of tongue to thryoid; within 2cm of midline; deep to strap muscles.
• Midline neck mass which moves downwards on swallowing.
• Ultrasound can easily identify cyst (contrast enhanced CT/MRI can also be used)
• Superinfection on ultrasound: thickened irregular wall with increased doppler flow.

Fig. 18: Hypoglossal cyst: Midline swelling in a 7 year old girl which moves on swallowing. Single doppler ultrasound images demonstrates a predominantly hypoechoiec well circumscribed lesion within the middle without internal vascularity.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Fig. 19: Hypoglossal cyst. Saggital contrast enhanced CT neck shows midline cystic lesion with peripheral enhancement, located adjacent to hyoid bone, compatible with hypoglossal cyst.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Mimics:

• Epidermoid/Dermoid cysts
• Lymph node
• Abscess

However these lesions are typically superfical to strap muscles.

Branchial Cleft Cysts:

Branchial cleft cysts can be seen on ultrasound or CT but are best assessed on MRI.  Anatomical location is key for diagnosis.

1. Second branchial cleft cyst:

• Most common
• Location: angle of mandible
• 10-40 years old
• Superinfection

2. First branchial cleft cyst:

• Related to parotid gland and can extend into external auditory canal.
• Uncommon in children

3. Third and fourth branchial cleft cysts:

• Rare
• Typically left sided, associated with fistulous tract to pyriform sinus (can be seen on barium study)
• Consider if cervical or thyroid abscess

Fig. 21: Third/Fourth branchial cleft cyst. Neonate with left fluctuant neck swelling (a)Axial contrast enhanced CT neck demonstrates peripheral enhancing fluid collection within left cervical region with stranding in surrounding soft tissues suggestive of infected fourth/fifth branchial cleft cyst.(b)Axial post contrast T1 image on same child performed two week later, demonstrates interval decrease in size of peripherally enhancing cystic lesion. Overall felt to infected fourth/fifth branchial cyst.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Retropharyngeal Abscess:

Retropharyngeal/Prevertebral abscesses occur from spread of infection from retropharyngeal lymph nodes and most commonly occur in children less than 6 months.

Other causes include trauma from foreign body ingestion or iatrogenic.

Fig. 22: Retropharyngeal Abscess. Lateral neck radiograph demonstrates marked prevertebral soft tissue swelling. Pseudothickening: Caution in paediatric imaging as neck flexion or incomplete inspiration can mimic prevertebral swelling.

Fig. 23: Retropharyngeal abscess: (a)Axial contrast enhanced CT neck shows peripherally enhancing collection in the right retropharyngeal region. (b)Corresponding saggital image.
References: Department of Radiology, OLCHC, Dublin/IE 2016

Imaging findings:

• Lateral neck radiograph: Preveretebral soft tissue swelling +/- gas
• Contrast enhanced CT/MRI: Fluid within the retropharyngeal space, peripheral rim enhancement (not seen in cellulitis)

Complications:

• Mediastinitis
• Necrotising cervical infection
• Internal jugular vein thrombosis
• Carotid artery involvement

Prompt identification of retropharyngeal abscesses due to risk of airway compromise or spread to mediastinum.

Fig. 24: Danger space. (a) Saggital and (b) axial contrast enhanced CT neck which demonstrates the danger space, a potential space located behind the true retropharyngeal space, which is only seen when distended with pus/fluid and thus allows extension of retropharyngeal abscess into the mediastinum.
References: Department of Radiology, OLCHC, Dublin/IE 2016