Laryngitis generically refers to inflammation of the tissues of the larynx, it is one of the most common conditions identified in the larynx and it manifests in both acute and chronic presentations.
In acute presentation the onset is usually abrupt, and the course of the illness is typically self-limiting; that is, less than 3 weeks.
In chronic presentation, signs and symptoms usually develop gradually over very long periods of time when the larynx is repetitively exposed to the offending agent over a longer duration.
Laryngitis can lead to oedema of the true vocal folds. Causes may be infectious or non-infectious (e.g., vocal strain, reflux laryngitis, chronic irritative laryngitis).
Laryngitis is often clinically diagnosed, with acute disease presenting with hoarseness that generally arises over a period of <7 days, this is usually preceded by a viral upper respiratory infection and is ordinarily self-limiting.
Patients may present with airway distress due to oedema and high fever. Exudative tonsillopharyngitis with fever and anterior cervical lymphadenitis is highly suggestive of a bacterial origin.
Epidemiology
Accurate figures with regard to acute laryngitis are difficult to collect, because it is generally unreported.
Sore throat accounts for 1% to 2% of all patient visits to a primary care physician in the US. This accounts for approximately 7.3 million annual visits for children and 6.7 million for adults.
One review conducted by the Royal College of General Practitioners in the UK in 2010 reported an average incidence of 6.6 cases of laryngitis and tracheitis per 100,000 patients (all ages) per week.
In addition, the incidence of chronic laryngitis is not well established but has been estimated as 3.47 diagnoses per 1000 people per year.
Viral agents tend to have annual periods of peak prevalence, such as rhinovirus infections in autumn and spring, and influenza virus infection epidemics generally from December to April. Laryngitis may occur due to croup or epiglottitis.
The recorded incidence of epiglottitis in the US declined between 1980 and 1990. These epidemiological changes have been ascribed to the introduction of the Haemophilus influenzae type B (Hib) vaccination.
Diphtheria is encountered rarely in developed nations but can still infect children and adults who are immunocompromised or have not received vaccinations. Worldwide, diphtheria is still endemic in areas such as Africa, Latin American, Asia, the Middle East, and parts of Europe where immunization coverage with diphtheria toxoid-containing vaccines is suboptimal.
Since 2011, large outbreaks have been reported in Indonesia, Laos, Haiti, Venezuela, Yemen, and Bangladesh. In 2017, the World Health Organization reported 8819 global cases of diphtheria.
Tuberculous laryngitis is historically a sequela of pulmonary tuberculosis (TB), but can present without pulmonary involvement.
Currently, in developed countries, TB is associated with people who have emigrated from endemic areas (e.g., China and India); have a history of HIV infection, and historically, the nursing home population and health care workers. However, over 95% of cases and deaths are in developing countries.
Approximately 8 million people worldwide are co-infected with HIV and TB, the majority of whom live in sub-Saharan Africa, the Indian subcontinent, and South East Asia.
Laryngeal candidiasis is more common in immune-suppressed patients, as well as among immune-competent patients using inhaled corticosteroids or prolonged courses of antibiotics [Ref_1].
Both acute and chronic laryngeal inflammation can be caused by phonotrauma, and/or exposure to environmental irritants or noxious agents, as well as allergens.
Aetiology
Infectious laryngitis
This may be caused by viral, bacterial, or fungal infection.
Virus infection:
- Generally the most common cause of infectious laryngitis
- Rhinovirus is the most common virus that is aetiologically associated with upper respiratory infections
- Other causative viruses include parainfluenza virus, respiratory syncytial virus, influenza, and adenoviruses
- Parainfluenza viruses type 1 and type 2, as well as influenza viruses, are the most common pathogens responsible for croup.
Bacterial infection:
- Pathogens consist of Moraxella catarrhalis, Haemophilus influenzae, Streptococcus pneumoniae, Staphylococcus aureus, and Klebsiella pneumoniae
- Epiglottitis is most frequently caused by Haemophilus influenzae type B
- Diphtheria is caused by Corynebacterium diphtheriae. Occasional cases may be caused by Corynebacterium ulcerans
- Although atypical forms of acid-fast bacilli can play a role, most tuberculosis infections are caused by Mycobacterium tuberculosis
- Syphilis is a less common cause.
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| Corynebacterium diphtheriae bacteria, stained using methylene blue; specimen taken from a Pai slant culture |
Fungal infections:
Generally caused by Candida albicans, Blastomyces dermatitis, Histoplasma capsulatum, and Cryptococcus neoformans.
Non-infectious laryngitis
These include the following:
- Irritant laryngitis (e.g., due to toxic exposure)
- Allergic
- Traumatic, especially due to heavy vocal use
- Reflux laryngitis
- Autoimmune.
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Pathophysiology
In acute infectious laryngitis there is generally a viral, bacterial, or fungal insult, leading to inflammation of the endolaryngeal structures. This results in tissue oedema and erythema.
Tissue oedema decreases the pliability of the true vocal fold mucosa over the lamina propria and increases the bulk of the vocal folds.
This leads to lowered vocal pitch, more strain, and a rougher voice or even aphonia.
In bacterial infection, there is increased mucus, as well as purulence. In more pronounced cases, especially in children in whom the larynx is already small, oedema may lead to narrowing of the airway and airway compromise.
Tuberculosis infection may lead to chronic laryngitis.
Reflux laryngitis results in irritation of the laryngeal mucosa from a repetitive exposure of refluxate containing hydrochloric acid and pepsin.
This leads to an oedematous, erythematous, and chronically inflamed larynx. With patients presenting with excessive throat clearing, coughing, hoarseness, and globus pharyngeus (i.e., the sensation of a lump in the throat).
Patients with heavy vocal use such as teachers, singers, lawyers, salespeople, etc., can put a great strain on their vocal folds in terms of repeat mechanical collisions.
Vocal folds experience intense friction, thermal agitation, and activation of inflammatory markers from physical trauma. This has been described as an inertial whiplash injury [Ref_2] [Ref_3].
This phonotrauma results in oedematous vocal folds, with increased risk of scarring and vocal fold haemorrhage.
Classification
According to cause:
Infectious:
- Viral: most common causative agent is the rhinovirus. Others include influenza A, B, C, adenoviruses, croup due to the parainfluenza viruses, measles, varicella-zoster
- Bacterial: examples include epiglottitis due to Haemophilus influenzae type B, beta-haemolytic Streptococcus
- Fungal: examples include candidiasis, blastomycosis, histoplasmosis, and cryptococcosis.
- Irritative laryngitis (e.g., due to toxic exposure)
- Allergic
- Traumatic, especially due to heavy vocal use
- Reflux laryngitis
- Autoimmune.
According to Onset and duration of symptoms
- Acute: usually lasts <7 days
- Chronic: persistence of symptoms for 3 weeks or longer
- Subacute: when the clinical presentation lies between 1 and 3 weeks. TThere is little clinical utility in using this definition.
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Approach to Diagnosis
Symptoms of acute infectious laryngitis may range from very subtle features to high-grade fever with airway compromise.
Subtle features may include short-lived mild hoarseness and upper respiratory infection (URI) symptoms.
The clinical presentation of laryngitis depends on:
- Causative pathogen
- Amount of tissue oedema
- Region of larynx primarily involved
- Age and comorbidities.
Evaluation of the airway is important as an initial step. Further evaluation then follows.
Urgent considerations
Upon presentation of acute laryngitis, the first system assessed should be the airway.
If there is respiratory distress, the patient should be assessed in a controlled environment with the facility to perform safe intubation.
Emergency tracheotomy may be required if, through swelling, a normal intubation is not possible.
Children presenting with symptoms and signs of epiglottitis (e.g., high fever, sore throat, toxic appearance, drooling, tripod positioning, difficulty breathing, and irritability) should be examined in a controlled setting, such as the operating room.
Intubation is performed if there is any doubt about the airway. If the patient is an adult, flexible laryngoscopy may be performed, depending on the level of distress.
If the patient is in severe respiratory distress, or if supraglottitis is suspected, then flexible laryngoscopy may trigger laryngospasm and airway demise. In these patients, laryngeal examination should be performed only by an otolaryngologist, and preferably in the operating room where a surgical airway can be secured if needed.
Any manipulation of the supraglottic area should be avoided. If necessary, intubation can be performed during flexible laryngoscopy with direct visualization.
Another common condition that can present with respiratory distress is croup. Epiglottitis and croup will not be covered in detail in this topic.
History
Once the airway is assessed and, if necessary, secured, the remainder of the history and examination can be performed.
A thorough history should include information about voice, breathing, and swallowing patterns. Concomitant systemic problems, such as allergies, exposures, immune deficiencies, and systemic illnesses, are considered.
History of intubations, radiation exposures, and neck surgery should be taken, as should a smoking history.
Knowledge of recent travel to areas where diphtheria or tuberculosis are endemic, or of contact with people with infectious symptoms, may aid in diagnosis.
Other risk factors for acute infectious laryngitis include incomplete or absent Haemophilus influenzae type B (Hib) or diphtheria vaccination.
Laryngeal candidiasis is more common in patients using inhaled corticosteroids or prolonged courses of antibiotics, and in those who are immune compromised.
Risk factors for tuberculosis (TB) (a cause of chronic laryngitis) include residence in a nursing home, HIV or other immunocompromise, and living or travelling to an endemic area.
There is often a precedent URI with sore throat, fever, cough, and rhinitis. This is followed by odynophagia, dysphagia, and hoarseness.
Fatigue and malaise can occur. Laryngeal oedema can lead to dyspnoea.
The challenge for the clinician is to decide which patients may have bacterial infection and require specific antibiotic treatment, because presentation of viral and bacterial laryngitis may be similar.
Viral laryngitis is common, and symptoms generally arise over a period of <7 days. Diphtheria is uncommon in the US and has a prodrome of several days, with hoarseness progressing to airway compromise.
Evidence of a bacterial infection elsewhere (e.g., pneumonia, streptococcal pharyngitis) supports a bacterial aetiology.
Chronic laryngitis is defined as throat inflammation of at least 3-week duration that encompasses a broad range of inflammatory, infectious, and autoimmune conditions resulting in alteration of phonation, breathing, and swallowing.
Symptoms of Chronic laryngitis include dysphonia, throat pain, globus sensation, frequent throat clearing, cough, and dysphagia. The symptoms of chronic laryngitis due to TB are prolonged (>3 weeks) and patients typically complain of dysphonia, but may also experience odynophagia, dysphagia, coughing, and rarely dyspnoea.
Symptoms generally mimic symptoms of laryngeal malignancy, which needs to be ruled out. Patients may have symptoms of cough and weight loss, but they are usually referred to an otolaryngologist due to persistent hoarseness.
Patients with traumatic laryngitis will present with hoarseness that has been going on for a prolonged duration and generally have a history of heavy vocal use.
These patients tend to be professional voice users such as teachers, lawyers, people in sales, or singers.
The hoarseness is usually worse with increased voice use; therefore, they have more complaints towards the end of the day and are better in the morning.
If they do voice rest, they tend to have improved voice quality. If there is an acute trauma, they can present with sudden onset loss of voice, which could be a sign of a vocal fold haemorrhage.
Physical examination
Generally, an adult with acute laryngitis will not be toxic in the absence of acute epiglottitis or diphtheria.
Patients may have hyperaemia of the oropharynx and possibly enlarged tonsils. There may be post-nasal drip on oropharyngeal examination.
Exudative tonsillopharyngitis, anterior cervical lymphadenitis, and fever are highly suggestive of a bacterial origin.
A patient with diphtheria can present with a sore throat, difficulty swallowing, malaise or be in acute respiratory distress. Oropharyngeal examination can reveal white-grey exudates, which may extend to the soft palate and vallecula.
These pseudomembranes may also be found covering the laryngeal structures, leading to airway compromise. Exudates are firmly adherent to the underlying mucosa, which bleed when the exudate is removed.
There is cervical lymphadenopathy, profound malaise, and stridor. The diphtheria toxin also causes cardiomyopathy and neuropathies.
Paralysis of the vocal folds or palate can be seen. Early diagnosis is imperative. Head and neck examination is usually normal in vocal trauma.
Patients with chronic laryngitis secondary to reflux may demonstrate laryngeal oedema, pseudosulcus, hyperaemia, increased mucus, granuloma, or thickening of the posterior interarytenoid tissue.
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| Young boy presenting with acute diphtheria infection |
Diagnostic tests
Laryngitis is a diagnosis of history and examination, rather than laboratory testing.
A thorough examination includes laryngoscopy.
This is performed if the patient presents initially to an otolaryngology specialist, but most primary care physicians are not experienced in the technique and diagnose most cases of viral laryngitis clinically.
Some primary care physicians may use mirror indirect laryngoscopy, depending on experience.
Laryngoscopy shows oedema and erythema of the laryngeal structures, especially the true vocal folds. Thick, copious, white-yellow secretions are also seen in the glottis.
If indirect laryngoscopy cannot be performed, the patient may be referred to an otolaryngology specialist.
Indications for referral to an otolaryngologist include:
- Uncertain diagnosis.
- Persistent hoarseness (lasting longer than 2-3 weeks) with failed treatment. It is important to refer these patients rather than treat them with further courses of antibiotics if symptoms do not improve or resolve within 4 weeks, or earlier if a serious underlying cause is suspected.
- Ill patients with suspected airway compromise. These patients are referred to hospital for urgent management and assessment.
- Patients whose profession relies on their voice.
Videostroboscopy allows for simultaneous evaluation of voice quality, laryngeal anatomy, and vocal fold vibratory function.
Guidelines on dysphonia encourage the use of videostroboscopic examination when the voice symptoms are out of proportion to the indirect laryngoscopy. Videostroboscopy can reveal vocal fold sulcus or vibratory pathologies such as stiffness or help differentiate between benign vocal lesions.
In case of suspected bacterial origin, oropharyngeal cultures and full blood count can be obtained, as well as a rapid antigen detection test.
If diphtheria is suspected, cultures of nose and throat swabs are obtained and Loeffler or Tindale selective media used.
Definitive diagnosis can also be made by the demonstration of toxin production by immunoprecipitation, polymerase chain reaction, or immunochromatography.
The work-up for patients with chronic laryngitis suspected to be due to tuberculosis includes a purified protein derivative skin test, chest x-ray, sputum cultures, and sputum smear for the detection of acid-fast bacilli.
Indirect laryngoscopy generally reveals exophytic or nodular lesions. Most commonly, the posterior glottis is involved, but the lesions can be seen anywhere in the larynx.
Because the laryngeal lesions look similar to carcinoma of the larynx, a direct laryngoscopy should be performed, and biopsies should be obtained. This procedure is usually performed under general anaesthesia by an otolaryngologist.
In vocal strain, history and examination to exclude other causes is usually sufficient to make the diagnosis. However, other aetiologies may exist in heavy voice users (including laryngeal malignancy); therefore, any hoarseness that does not improve or resolve within 4 weeks should be evaluated by an otolaryngologist with a laryngoscopy.
If a serious underlying cause is suspected, the patient should be referred irrespective of duration.
Differential diagnosis
- Tonsillitis
- Infectious mononucleosis
- Allergic rhinitis
- Laryngeal carcinoma
- GORD