Role of Ultrasound in Laryngeal Lesions

The larynx contains the vocal cords and serves as the opening to the tracheobronchial tree. Laryngeal lesions include: benign laryngeal tumors, contact ulcers, laryngitis, laryngeoceles, malignant laryngeal tumors, spasmodic dysphonia, vocal cord paralysis, vocal cord polyps, nodules and granulomas.

Laryngeal cancers account for about one quarter of all head and neck cancers, most of which affect the true vocal cords. Black men are affected more commonly than white men. The male to female incidence ratio is about 4:1.

Laryngeal cancer is the 19th most common cause of cancer death worldwide, with around 83,400 deaths from laryngeal cancer in 2012 (1% of total cancer deaths). Cancer of larynx is one of the most common malignancies in Europe, with about 52,000 new cases per year. The yearly incidence rate in Europe is about 8 per 100,000.

Different methods were used successfully for the diagnosis of many laryngeal diseases. Rigid endoscope was used for laryngeal evaluation with the advantage that the image is large, bright and clear which allows early diagnosis of the lesion (Shao et al, 2002).

Unfortunately, not all patients can tolerate the laryngoscope especially those with a sensitive gag reflex, patients with limit of jaw or neck mobility or patients suffering from stridor. It is also difficult in most infants and children .

Even during laryngoscopy the exact extension of laryngeal tumor, its infiltration and invasion of the laryngeal skeleton can sometimes be hard to assess. Thus, laryngoscopy alone may not be sufficient in some cases to judge the extent of infiltrative processes or measure the exact infiltration of a tumor. For this reason computed tomography (C.T) as well as magnetic resonance imaging (MRI) is often used to supplement laryngoscope as an additional imaging tool in the estimation of tumor extension and size.

Ultrasonography is a non-invasive modality, available at almost all institutions, not expensive, easily reproducible method of examining the larynx in infants and children, can be used safely during pregnancy in contrast to scan, portable and can be easily transferred to patients with difficult mobilization.

Ultrasound became a very important, widely used diagnostic tool for head and neck diseases; however, it was rarely used in the diagnosis of laryngeal diseases. This was because of the problem in visualization of laryngeal structures and thus in performing a complete laryngeal sonographic examination due to the acoustic extinction of the ultrasound by the ossified laryngeal cartilages .

Researchers have recently used color Doppler imaging to study the surface mucosal waves of the vocal folds. During the last several years high-frequency ultrasound became an effective diagnostic tool with small, flexible ultrasound transducers .