Thumb sign

Thumb sign is a medical term used in radiology to describe the appearance of the epiglottis and surrounding tissues on a lateral neck radiograph in patients with acute epiglottitis. The thumb sign is indicative of an enlarged epiglottis, which can be a life-threatening condition requiring immediate medical attention.

Definition

The thumb sign is named for its resemblance to a thumbprint on a lateral neck radiograph. It is caused by the swelling of the epiglottis, a flap of tissue located at the base of the tongue that prevents food and liquid from entering the windpipe during swallowing. In cases of acute epiglottitis, the epiglottis can swell to several times its normal size, leading to the thumb sign on radiographs.

Causes

The most common cause of the thumb sign is acute epiglottitis, an inflammation of the epiglottis usually caused by bacterial infection. The most common bacteria responsible for epiglottitis is Haemophilus influenzae type b (Hib), although other bacteria and viruses can also cause the condition. Other causes of the thumb sign can include trauma to the throat, allergic reactions, and certain systemic diseases.

Diagnosis

The thumb sign is diagnosed through a lateral neck radiograph, which is a type of X-ray that provides a side view of the neck. The radiograph can reveal the enlarged epiglottis characteristic of the thumb sign. Other diagnostic methods can include a physical examination of the throat and laboratory tests to identify the cause of the inflammation.

Treatment

Treatment for the thumb sign involves addressing the underlying cause of the epiglottis swelling. This usually involves antibiotics to treat bacterial infections, although other treatments may be necessary depending on the cause. In severe cases, a procedure known as a tracheostomy may be necessary to prevent airway obstruction.

See also

• Epiglottitis
• Haemophilus influenzae
• Tracheostomy