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What is Laryngitis and explain in detail?
Laryngitis is inflammation of the larynx (voice box). Symptoms often include a hoarse voice and may include fever, cough, pain in the front of the neck, and trouble swallowing. Typically, these last under two weeks.Laryngitis is categorised as acute if it lasts less than three weeks and chronic if symptoms last more than three weeks. Acute cases usually occur as part of a viral upper respiratory tract infection, other infections and trauma such as from coughing are other causes. Chronic cases may occur due to smoking, tuberculosis, allergies, acid reflux, rheumatoid arthritis, or sarcoidosis. The underlying mechanism involves irritation of the vocal cords.Concerning signs that may require further investigation include stridor, history of radiation therapy to the neck, trouble swallowing, duration of more than three weeks, and a history of smoking. If concerning signs are present the vocal cords should be examined via laryngoscopy. Other conditions that can produce similar symptoms include epiglottitis, croup, inhaling a foreign body, and laryngeal cancer.The acute form generally resolves without specific treatment. Resting the voice and sufficient fluids may help. Antibiotics generally do not appear to be useful in the acute form. The acute form is common while the chronic form is not. The chronic form occurs most often in middle age and is more common in men than women.

Signs and symptoms
The primary symptom of laryngitis is a hoarse voice.: 108  Because laryngitis can have various causes, other signs and symptoms may vary. They can include

Dry or sore throat
Coughing (both a causal factor and a symptom of laryngitis)
Frequent throat clearing
Increased saliva production
Dysphagia (difficulty swallowing)
Sensation of swelling in the area of the larynx (discomfort in the front of the neck)
Globus pharyngeus (feeling like there is a lump in the throat)
Cold or flu-like symptoms (which, like a cough, may also be a causal factor for laryngitis)
Swollen lymph nodes in the throat, chest, or face
Fever
General muscle pain (myalgia)
Shortness of breath, predominantly in children

Voice quality
Aside from a hoarse-sounding voice, changes to pitch and volume may occur with laryngitis. Speakers may experience a lower or higher pitch than normal, depending on whether their vocal folds are swollen or stiff. They may also have breathier voices, as more air flows through the space between the vocal folds (the glottis), quieter volume and a reduced range.

Causes
Laryngitis can be infectious as well as noninfectious in origin. The resulting inflammation of the vocal folds results in a distortion of the sound produced there. It normally develops in response to either an infection, trauma to the vocal folds, or allergies. Chronic laryngitis may also be caused by more severe problems, such as nerve damage, sores, polyps, or hard and thick lumps (nodules) on the vocal cords.[4]

Acute
Viral
Most acute cases of laryngitis are caused by viral infections, the most common of which tend to be rhinovirus, influenza virus, parainfluenza virus, adenovirus, coronavirus, and RSV. In patients who have a compromised immune system, other viruses such as herpes, HIV may also be potential causes.

Bacterial
This is another major cause of acute laryngitis, and may develop in conjunction with or due to a viral infection. Common bacterial strains are group A streptococcus, Streptococcus pneumoniae, C. diphtheriae, M. catarrhalis, Haemophilus influenzae, Bordetella pertussis, Bacillus anthracis, and M. tuberculosis. In developing countries, more unusual bacterial causes may occur, such as mycobacterial and syphilitic, though these may occur in developed nations as well.

Fungal
Laryngitis caused by fungal infection is common but not frequently diagnosed according to a review by BMJ and can account for up to 10% of acute laryngitis cases. Patients with both functioning and impaired immune systems can develop fungal laryngitis, which may develop as a result of recent antibiotic or inhaled corticosteroids use. Certain strains of fungi that may cause laryngitis include; Histoplasma, Blastomyces, Candida (especially in immunocompromised persons), and Cryptococcus and Coccidioides.

Trauma
Often due to excessive use of the vocal folds such as excessive yelling, screaming, or singing. Though this often results in damage to the outer layers of the vocal folds, the subsequent healing may lead to changes in the physiology of the folds. Another potential cause of inflammation may be overuse of the vocal cords.[5] [6] [7] [8] [9] Laryngeal trauma, including iatrogenic (caused by endotracheal intubation), can also result in inflammation of the vocal cords.

Chronic
Allergies
Findings are unclear as to whether asthma may cause symptoms commonly associated with laryngitis. Some researchers have posited that allergic causes of laryngitis are often misdiagnosed as being the result of acid reflux.

Reflux
One possible explanation of chronic laryngitis is that inflammation is caused by gastro-oesophageal reflux, which causes subsequent irritation of the vocal folds.

Autoimmune disorders
Approximately between 30 and 75% of persons with rheumatoid arthritis report symptoms of laryngitis.
Symptoms of laryngitis are present in only 0.5–5% of people that have sarcoidosis. According to a meta-analysis by Silva et al. (2007), this disease is often an uncommon cause of laryngeal symptoms and is frequently misdiagnosed as another voice disorder.

Diagnosis
Diagnosis of different forms of acute laryngitis

Laryngitis following trauma: This form of laryngitis is usually identified by obtaining a case history providing information on previous phono traumatic experiences, internal trauma caused by recent procedures as well as any previous neck injuries.
Acute viral laryngitis: This form of laryngitis is characterized by lower vocal pitch as well as hoarseness. The symptoms in this form of laryngitis are usually present for less than one week, however they can persist for 3–4 weeks. This form of laryngitis might also be accompanied by upper respiratory tract symptoms such as: sore throat, odynophagia, rhinorrhea, dyspnea, postnasal discharge, and congestion.
Fungal laryngitis: A biopsy and culture of abnormal lesion may help confirm fungal laryngitis.

Visual diagnosis
The larynx itself will often show erythema (reddening) and edema (swelling). This can be seen with laryngoscopy or stroboscopy (method depends on the type of laryngitis).: 108  Stroboscopy may be relatively normal or may reveal asymmetry, aperiodicity, and reduced mucosal wave patterns.Other features of the laryngeal tissues may include
Redness of the laryngeal tissues (acute)
Dilated blood vessels (acute)
Thick, yet dry laryngal tissue (chronic)
Stiff vocal folds
Sticky secretions between the vocal folds and nearby structures (the interarytenoid region)

Referral
Some signs and symptoms indicate the need for early referral. These include

Difficulty swallowing
Vocal stridor
Ear pain
Recent weight loss
History of smoking
Current or recent radiotherapy treatment (in the neck region)
Recent neck surgery or surgery involving endotracheal tubing
Person is a professional voice user (teacher, singer, actor, call center worker, and so on)

Differential diagnosis
Acute epiglottitis: This is more likely in those with stridor, drooling, and painful or trouble swallowing.
Spasmodic dysphonia
Reflux laryngitis
Chronic allergic laryngitis
Neoplasm
Croup: This presents with a barking cough, hoarseness of voice, and inspiratory stridor.

Treatment
Treatment is often supportive in nature, and depends on the severity and type of laryngitis (acute or chronic). General measures to relieve symptoms of laryngitis include behaviour modification, hydration and humidification.Vocal hygiene (care of the voice) is very important to relieve symptoms of laryngitis. Vocal hygiene involves measures such as: resting the voice, drinking sufficient water, reducing caffeine and alcohol intake, stopping smoking and limiting throat clearing.

Acute laryngitis
In general, acute laryngitis treatment involves vocal hygiene, painkillers (analgesics), humidification, and antibiotics.

Viral
The suggested treatment for viral laryngitis involves vocal rest, pain medication, and mucolytics for frequent coughing. Home remedies such as tea and honey may also be helpful. Antibiotics are not used for treatment of viral laryngitis.

Bacterial
Antibiotics may be prescribed for bacterial laryngitis, especially when symptoms of upper respiratory infection are present. However, the use of antibiotics is highly debated for acute laryngitis.  This relates to issues of effectiveness, side effects, cost, and possibility of antibiotic resistance patterns. Overall, antibiotics do not appear to be very effective in the treatment of acute laryngitis.In severe cases of bacterial laryngitis, such as supraglottitis or epiglottitis, there is a higher risk of the airway becoming blocked. An urgent referral should be made to manage the airway. Treatment may involve humidification, corticosteroids, intravenous antibiotics, and nebulised adrenaline.

Fungal
Fungal laryngitis can be treated with oral antifungal tablets and antifungal solutions. These are typically used for up to three weeks and treatment may need to be repeated if the fungal infection returns.

Trauma
Laryngitis caused by excessive use or misuse of the voice can be managed though vocal hygiene measures.

Chronic laryngitis
Reflux
Laryngopharyngeal reflux treatment primarily involves behavioural management and medication. Behavioural management involves aspects such as

Wearing loose clothing
Eating smaller, more frequent meals
Avoiding certain foods (e.g. caffeine, alcohol, spicy foods)Anti-reflux medications may be prescribed for patients with signs of chronic laryngitis and hoarse voice. If anti-reflux treatment does not result in a decrease of symptoms, other possible causes should be examined. Over-the-counter medications for neutralizing acids (antacids) and acid suppressants (H-2 blockers) may be used. Antacids are often short-acting and may not be sufficient for treatment. Proton pump inhibitors are an effective type of medication. These should only be prescribed for a set period of time, after which the symptoms should be reviewed. Proton pump inhibitors do not work for everyone