What is laryngitis?
Laryngitis is the medical term for inflammation of the larynx (voice box). This is the part of the respiratory tract that connects the pharynx (throat) to the trachea (wind pipe) and contains the vocal apparatus to produce sound. The most common causes of laryngitis are an infection and trauma (chemical and mechanical injury including vocal strain).
Most cases of laryngitis are acute, meaning that it last for a short period of time, anywhere from a few days (usually 7 to 10 days) to 2 to 3 weeks. Chronic laryngitis is inflammation of the larynx that lasts for more than 3 weeks and may sometimes be due to serious and even life threatening illnesses.
How does laryngitis occur?
Any injury or infection may result in inflammation of the lining of the larynx as well as the vocal cords. The results in increased blood flow (redness ~ erythema) to the area and swelling (edema). The vocal cord may become thicker or possibly even stiffer and this affects the pitch of the voice. Phonation, which is the ability to produce sound, is impaired (dysphonia) and if it is painful, a person may be unable to vibrate the vocal cords sufficiently to produce any sound (aphonia).
Often the inflammation is not isolated to the larynx. An infection may affect the neighboring structures like the pharynx and trachea and this causes a range of additional symptoms. One example is croup. This is the inflammation of the larynx as well as the trachea coupled with bronchitis and is known as laryngotracheobronchitis. It is a viral infection that is common in children and is most noticeable by a hoarse, bark-like cough as well as abnormal breathing sounds.
Symptoms of Laryngitis
The most common symptoms of laryngitis are a hoarse voice or gruff, low volume voice similar to a whisper. This is known as dysphonia. However, laryngitis is not the only cause of hoarseness of the voice. Refer to Hoarse Voice for a list of possible causes in babies, children and adults. Less frequently, laryngitis may lead to a complete loss of voice (aphonia).
Other symptoms may include a sore throat, cough and a fever in infectious cases. Difficulty swallowing (dysphagia) or discomfort and even pain upon swallowing (odynophagia) may also be present. Pain when talking, especially if speaking loudly, is known as odynophonia, and may also be present in laryngitis.
If dysphonia or aphonia is accompanied by any significant difficulty in breathing, abnormal breathing sounds like a stridor, pallor (pale skin) or cyanosis (bluish discoloration of the skin), then this may be due to a laryngeal obstruction or bilateral paralysis (vocal cords) and needs immediate medical attention.
Acute Infectious Laryngitis
Usually community-acquired upper and lower respiratory tract viral infections are the main causes of acute infectious laryngitis. It is often transmitted through droplet spread (sneezing, coughing, contaminated objects) and most are contagious. This may involve a wide range of viruses that cause the following conditions :
- Seasonal flu (influenza)
- Swine flu (H1N1)
- Common cold with/without fever
- Ear infections (otitis)
In addition, respiratory syncytial viruses (RSV) which cause respiratory tract infections in children are another common cause of acute infectious laryngitis. These viruses are easily spread from child to child in the school or daycare setting.
Whooping cough (pertussis), which is caused by the bacteria Bordetella pertussis, is another cause of laryngitis. It is more common in children and infants. Furthermore, childhood diseases like mumps, measles, and chickenpox may also cause laryngitis.
Chronic Infectious Laryngitis
Most of the infections mentioned above account for acute cases of laryngitis, however, certain microorganisms may be responsible for chronic laryngitis. These infections are not usually contagious but person-to-person transmission is possible. This includes :
- These infections may arise secondary to case of viral laryngitis. Bacteria that me be responsible include :
- Staphylococcus aureus
- Haemophilus influenzae
- Mycobacterium tuberculosis (TB)
- Mycobacterium leprae (leprosy)
- Treponema pallidum (syphilis)
- Fungal laryngitis is rare but may occur in immunocompromised states (like in HIV/AIDS), use of certain drugs or following radiation therapy. Fungi that may be responsible include :
- Candida spp (candidal laryngitis)
- Other fungal infections are rare but may include blastomycosis, histoplasmosis, coccidiosis and aspergillosis.