Intern Ultrasound of the Month: Peritonsillar Abscess
The Case
A previously healthy male in his mid 20s presented for sore throat x 5 days. He had been evaluated in the ED about 36 hrs earlier, where he was noted to have posterior pharyngeal erythema. He tested positive for strep and was discharged on oral antibiotics. After going home he developed worsening throat pain/odynophagia and was not really tolerating PO as a result. He also reported predominantly left-sided neck pain, subjective fever, and chills, and felt like his voice sounded different.
Vitals were within normal limits. Exam revealed an uncomfortable-appearing male in no acute distress. He had a slightly muffled voice and dysphonia but easily speaking in full sentences, no respiratory distress and handling secretions. Oropharyngeal exam was significant for mild trismus, left tonsillar swelling, bilateral exudates; uvula was midline. He also had tender left anterior cervical lymphadenopathy and some difficulty extending his neck due to pain.
Point-of-care ultrasound, using a submandibular approach (probe marker toward pt earlobe), was performed and showed the following:
Fanning the probe superiorly, we found a well-circumscribed hypoechoic, somewhat heterogenous, fluid collection with septation, ~2cm. Carotid artery visualized on far left.
Color doppler showing lack of flow.
The opposite/unaffected side was also evaluated for comparison and was normal-appearing. The circular structure seen in the middle of the image is the carotid (color flow not shown here).
We then moved more caudally near the level of the cords and fanned slightly cephalad.
*For this view we kept the probe marker in “standard” orientation on both sides with the probe marker pointing toward patient right
A somewhat poorly defined, heterogenous hypoechoic area was visualized posterolateral to the hypopharynx
Again, we compared it to the right side where anatomy was more clearly defined.
The patient was given IV Unasyn and steroids. A CT neck with contrast was obtained to better evaluate for deeper neck space infection and was consistent with POCUS findings — a left PTA measuring just under 2cm (with septation) and nonspecific inflammatory changes in the left hypopharyngeal region, likely phlegmon, starting to extend to the retropharyngeal space
ENT was consulted. They considered taking the patient to the OR given the parapharyngeal findings but opted for conservative management since it was a phlegmon rather than abscess at that point. Bedside I&D of the PTA was performed and the patient was admitted for close airway monitoring and IV antibiotics. Aspirate cultures grew group A strep. He did well and was discharged home on antibiotics the next day.
Deep Neck Space Infections
Peritonsillar Abscess (PTA)
Considered a deep neck space infection and is the most common type
What is it? — a collection of pus between the palatine tonsil & pharyngeal muscles
Epidemiology: 30 cases per 100,000 people per year
Primarily affects older children & young adults
Most commonly associated with tonsillitis
Clinical features commonly include:
Severe sore throat, often unilateral
Fever
Muffled voice
Trismus (seen in majority of cases)
Unilateral tonsillar enlargement with fluctuance, leading to cause uvula deviation
If untreated can spread to parapharyngeal/retropharyngeal spaces
Diagnosis: often clinical; CT & ultrasound useful adjuncts
Treatment: I&D vs needle aspiration — source control is most important, antibiotics/supportive care
Parapharyngeal & Retropharyngeal Infections
High morbidity/mortality due to proximity to the airway & major vasculature and contiguity with the “danger space” which communicates with the mediastinum
Most commonly associated with dental and tonsillar infections
Far less common than PTA, rare in older children & adults (especially RPA)
Clinical features may be vague (especially very young children), may mimic pharyngitis/tonsillitis and/or may include:
Dysphonia, stridor
Submandibular swelling
Neck stiffness or pain with movement
Systemic toxicity
Diagnosis: xray, CT most common
Treatment: ABCs, parenteral antibiotics, +/- surgical intervention for drainage
POCUS for PTA
Ultrasound is a valuable diagnostic tool for PTA
Transoral approach using the endocavitary probe is the more well-known technique
Sensitivity of 90% (compared to physical exam alone - sens 78%, spec 50%) (Scott)
Associated with less ENT consultation & CT utilization; also achieves better aspiration of purulent material when compared to a landmark approach (Constantino et al)
Submandibular approach with the linear (or curvilinear) probe is a great alternative
Technique:
Linear probe placed just under and parallel to the mandible, probe marker pointing toward the patient’s ear
Fan through the area, use color flow to differentiate from vasculature
Look for fluid collection near the tonsil
Compare to the unaffected side (as demonstrated above)
Limited data but has demonstrated relatively high sensitivity/specificity (Araujo Filho et al; Halm et al, Rehrer et al)
Advantages over transoral: less discomfort to the patient, more easily implementable (linear probes more readily available than endocavitary), can be utilized in cases of severe trismus
For both approaches, US can also aid in aspiration success (ultrasound-guidance)
Why use POCUS?
Relatively high sensitivity/specificity for PTA
Can helps confirm clinical diagnosis & expedite time to treatment
Less time-consuming, less costly, no radiation exposure compared to CT
Helps distinguish abscess from cellulitis
Higher success rate with aspiration of PTA compared to blind landmark approach
**POCUS for parapharyngeal/retropharyngeal infections also not well-studied but may have some utility as demonstrated in this case
Key Learning Points:
Consider POCUS as adjunct for physical exam when concerned for PTA (you don’t often need CT)
Transcutaneous submandibular technique is a great, readily available option
Fan the probe, apply color doppler
Compare to the opposite (hopefully normal) side
Can also evaluate the deeper neck spaces for abnormal fluid/inflammatory changes
Here’s a video demonstrating the submandibular technique: MGH - Submandibular approach for PTA
POST BY: DR. EMILY CRAFT, PGY1
FACULTY EDITING BY: DR. LAUREN MCCAFFERTY
References
Araujo Filho BC, Sakae FA, Sennes LU, Imamura R, de Menezes MR. Intraoral and transcutaneous cervical ultrasound in the differential diagnosis of peritonsillar cellulitis and abscesses. Braz J Otorhinolaryngol. 2006;72(3):377–81.
Buckley J, Harris AS, Addams-Williams J. Ten years of deep neck space abscesses. J Laryngol Otol.2019;133(4):324-328.
Costantino TG, Satz WA, Dehnkamp W, Goett H. Randomized trial comparing Intraoral ultrasound to landmark-based needle aspiration in patients with suspected peritonsillar abscess. Acad Emerg Med. 2012Jun;19(6):626-31.
Halm BM, Ng C, Larrabee YC. Diagnosis of a Peritonsillar Abscess by Transcutaneous Point-of-Care Ultrasound in the Pediatric Emergency Department. Pediatr Emerg Care. 2016;32(7):489-492.
Herzon FS, Harris P. Mosher Award thesis. Peritonsillar abscess: incidence, current management practices, and a proposal for treatment guidelines. Laryngoscope. 1995;105:1-17.
Rehrer M, Mantuani D, Nagdev A. Identification of peritonsillar abscess by transcutaneous cervical ultrasound. Am J Emerg Med. 2013;31(1):267.e1-267.e3.
Scott PM. Diagnosis of peritonsillar infections: a prospective study of ultrasound, computerized tomography and clinical diagnosis. J Laryngol Otol. 1999;113(3):229-32.
Secko M, Sivitz A. Think ultrasound first for peritonsillar swelling. Am J Emerg Med. 2015;33:569-572.
Simard RD, Socransky S, Chenkin J. Transoral point-of-care ultrasound in the diagnosis of parapharyngeal space abscess. J Emerg Med. 2019;56(1):70-73.
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