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Neuroradiology Case of the Week
Case 410
May 2009
Gurshawn Singh, MS2, Rajiv Mangla, MD, David Tuttle, MD,
and
P-L Westesson, MD, PhD, DDS
Clinical
Presentation: Patient is a 75-year-old female with sore throat.
Imaging Findings: On a sagittal CT scan, the epiglottis is inflamed and shows the classic “thumb sign”. Axial CT images show thickening of epiglottis and median glossoepiglottic fold.
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Figure 1: Classical "thumb sign" of epiglottis on lateral neck radiograph.
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Figure 2: Axial CT showing thickening of epiglottis.
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Diagnosis: Acute epiglottitis
Discussion: The epiglottis is a flap of tissue that covers the airway so food does not enter the trachea when swallowing. This tissue along with its surrounding tissues can get infected in progressive bacterial infiltration or Haemophilus influenzae type B. Before the influenza vaccine era, there was a large occurrence of the disease (100 per 100,000), and since the disease significantly dropped in occurrence (0.3 per 100,000). There are few other microbes like H. parainfluenzae, streptococcus pneumoniae, staph aureus, Group A beta hemolytic streptococcus and type A and F strain of H. influenza which also can cause epiglottitis occasionally.
Patients usually presents acutely with fever, sore throat, dysphagia, and drooling. Airway obstruction and stridor are also very prevalent by the nature of the pathology. The epiglottis gets inflamed and will therefore obstruct the airway. The risk of death is very high because of the obstructed airway and the inability to intubate patients. Adult patients present with milder symptoms than pediatric patients due to a larger airway. The condition is usually misdiagnosed in adults because of the common symptoms. Intubation can be mistakenly attempted and may result in death.
Diagnosis of epiglottitis must be first considered clinically. Since the disease is life-threatening, it is essential an early diagnosis is made. There can be other conditions like laryngotrachetis, spasmodic croup, bacterial tracheitis, uvulitis peritonsillar abscess and congenital anomalies of the airway which mimic epiglottis. Lateral radiographs images of the neck can be useful in confirming the diagnosis. The epiglottis is usually 3-5 mm in thickness but when the epiglottis has reached 7 mm, the diagnosis is epiglottitis can be suggested. A swollen epiglottis is referred to as the “thumb sign” since the epiglottis looks like a thumb rather than a flap. This condition is usually milder in adults and sometimes can not be appreciated on lateral radiograph leading to high false negative rates for diagnosis of epiglottis in adults. CT can be used in order to confirm and evaluate the other differential diagnosis of this condition. The term supraglottitis has also been used to describe this entity in adults as it is accompanied with inflammation of aryepiglottic folds, uvula and vallecula.
References:
- Nemzek WR, Katzberg RW, Van Slyke MA, Bickley LS. A reappraisal of the radiologic findings of acute inflammation of the epiglottis and supraglottic structures in adults. AJNR Am J Neuroradiol. 1995 Mar;16(3):495-502. [PubMed]
- Bowman JG. Epiglottitis, adult. eMedicine. April 10, 2009. http://emedicine.medscape.com/article/763612-overview
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