eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Laryngology

Acute Laryngitis

Author: Rahul K Shah, MD, FACS, FAAP, Assistant Professor of Otolaryngology and Pediatrics, George Washington University School of Medicine and Health Sciences; Attending Physician, Department of Otolaryngology, Children's National Medical Center
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Updated: Sep 25, 2009

Introduction

Background

Laryngitis is one of the most common conditions identified in the larynx. Laryngitis, an inflammation of the larynx, manifests in both acute and chronic forms.

Acute laryngitis has an abrupt onset and is usually self-limited. If a patient has symptoms of laryngitis for more than 3 weeks, the condition is classified as chronic laryngitis. The etiology of acute laryngitis includes vocal misuse, exposure to noxious agents, or infectious agents leading to upper respiratory tract infections. The infectious agents are most often viral but sometimes bacterial.

Chronic laryngitis, as the name implies, involves a longer duration of symptoms; it also takes longer to develop. Chronic laryngitis may be caused by environmental factors such as inhalation of cigarette smoke or polluted air (eg, gaseous chemicals), irritation from asthma inhalers, vocal misuse (eg, prolonged vocal use at abnormal loudness or pitch), or gastrointestinal esophageal reflux. Vocal misuse results in an increased adducting force of the vocal folds with subsequent increased contact and friction between the contacting folds. The area of contact between the folds becomes swollen. Vocal therapy has the greatest benefit in the patient with chronic laryngitis.

Although acute laryngitis is usually not a result of vocal abuse, vocal abuse is often a result of acute laryngitis. The underlying infection or inflammation results in a hoarse voice. Typically, the patient exacerbates the dysphonia by misuse of the voice in an attempt to maintain premorbid phonating ability.

Pathophysiology

Acute laryngitis is an inflammation of the vocal fold mucosa and larynx that lasts less than 3 weeks. When the etiology of acute laryngitis is infectious, white blood cells remove microorganisms during the healing process. The vocal folds then become more edematous, and vibration is adversely affected. The phonation threshold pressure may increase to a degree that generating adequate phonation pressures in a normal fashion becomes difficult, thus eliciting hoarseness. Frank aphonia results when a patient cannot overcome the phonation threshold pressure required to set the vocal folds in motion.

The membranous covering of the vocal folds is usually red and swollen. The lowered pitch in laryngitic patients is a result of this irregular thickening along the entire length of the vocal fold. Some authors believe that the vocal fold stiffens rather than thickens. Conservative treatment measures, as outlined below, are usually enough to overcome the laryngeal inflammation and to restore the vocal folds to their normal vibratory activity.

Frequency

United States

The exact prevalence of acute laryngitis is not reported because many patients often use conservative measures to treat their inflammation rather than seek medical consultation. Symptoms of an upper respiratory tract infection often accompany the disease; thus, patients are accustomed to managing their own treatment. Nevertheless, laryngitis is one of the most common laryngeal pathologies.

Mortality/Morbidity

Because acute laryngitis is usually self-limited and treated with conservative measures, significant morbidity and mortality are not encountered. Patients who develop acute laryngitis from an infectious etiology rather than vocal trauma may ultimately injure their vocal folds. The deficient voice production in patients with acute laryngitis may result in application of a greater adduction force or tension to compensate for the incomplete glottic closure during an acute laryngitic episode. This tension further strains the vocal folds and decreases voice production, ultimately delaying return of normal phonation.

• In 1997, Ng conducted a study of the aerodynamic and acoustic characteristics of acute laryngitis.¹ His study demonstrated that across the 5 vowels, the fundamental frequency values were lower in patients with acute laryngitis than in patients with a normal voice. The authors concluded that acute laryngitis changes the vocal fold mass, resulting in a reduction of the fundamental frequency; other authors have anecdotally corroborated this finding.²
• Patients with acute laryngitis have an increased open quotient value. This indicates that the patient's vocal folds are open longer, and less time is spent in the closed position, which contributes to the hoarseness and breathiness of the voice.

Age

Studies have demonstrated that, usually, acute laryngitis affects individuals aged 18-40 years. Children, a category not included in the above study, are clinically observed with acute laryngitis when aged 3 years and older.

Clinical

History

In addition to symptoms of an upper respiratory tract infection (ie, fever, cough, rhinitis), the patient also experiences dysphonia or a hoarse voice. A hoarse voice is defined as one that has the components of breathiness and tension.¹ These symptoms are consistent with laryngitis and are not specific for acute or chronic laryngitis. Patients with laryngitis may also experience odynophonia, dysphagia, odynophagia, dyspnea, rhinorrhea, postnasal discharge, sore throat, congestion, fatigue, and malaise.³ The patient's vocal symptoms usually last 7-10 days. If symptoms persist longer than 3 weeks, a workup for chronic laryngitis should be performed.

Physical

As Postma indicates, the diagnosis of acute laryngitis may be made solely based on the history and symptoms; thus, visual examination of the larynx is not always imperative. Certainly, if seen by an otolaryngologist, the patient would have a thorough examination of the head and neck, involving visual inspection of the larynx. Delay in referral to an otolaryngologist for 3 weeks may be acceptable for a primary care physician. However, an otolaryngologist who does not perform laryngoscopy in a patient with hoarseness may miss other pathologies, such as cancer, vocal nodules, or papillomas. Delaying examination of the larynx is unacceptable for an otolaryngologist.

• Other than findings of a common upper respiratory tract infection, the patient may appear healthy.
• Indirect examination of the airway with a mirror or direct examination with a flexible nasolaryngoscope reveals erythema and edema of the vocal folds, secretions, and irregularities of the surface contour of the vocal folds. Note the presence of normal vocal fold mobility and the absence of airway obstruction.

Causes

Any of the following etiologies may cause acute laryngitis:

• Infection (usually viral upper respiratory tract infection)³
  • Rhinoviruses
  • Parainfluenza viruses
  • Respiratory syncytial virus
  • Adenoviruses
  • Influenza viruses
  • Measles virus
  • Mumps virus
  • Bordetella pertussis
  • Varicella-zoster virus
• Gastroesophageal reflux disease
• Environmental insults (pollution)
• Vocal trauma
• Use of asthma inhalers

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