Table of Contents
- Structure and Functions of the Muscles of the Larynx
- A Clinical Approach to Larynx
- Inflammations of Larynx
- Congenital Lesions of the Larynx
- Non-Neoplastic Lesions
- Neoplastic Lesions
- Laryngeal Carcinoma
- Diagnosing the Cancer
- Treatment Options for Laryngeal Carcinoma
- Vocal Rehabilitation after Treatment
- Vocal Cord Paresis
- Popular Exam Questions on the Larynx
Structure and Functions of the Muscles of the Larynx
In infants, larynx is a conical space with soft and compressible cartilages situated a bit higher against C3 or C4 vertebrae and reaches C1 or C2 while swallowing.
Normal Functions of Larynx:
- Protection of the lower airways (preventing large foreign body to pass into lungs)
- Production of voice with assistance of the lips, tongue, palate and pharynx
- Respiration / Breathing (controlling the air column and amount of the air passing through it)
- Fixation of the chest while climbing, pulling and digging
A Clinical Approach to Larynx
The larynx forms the inlet of the airways and is exposed to bacteria and viruses leading to various infections. Even trauma can lead to disturbance of laryngotracheal anatomy and physiology.
Road traffic accidents, direct blow to the neck, strangulation, penetrating injuries, and gunshot wounds can lead to trauma to the larynx.
Laryngo-tracheal trauma can be suspected if the following signs and symptoms are present after a trauma episode:
- Hoarseness of voice
- Painful or difficulty in swallowing with aspiration of food particles
- Dyspnea with or without stridor
- Bruises on the neck skin with or without tenderness on palpation
- Displacement of cartilages due to fracture with or without bony crepitus
Laryngeal edema, hematoma or mucosal tear with asymmetry of the glottis or laryngeal inlet revealed on the laryngoscopy confirms the trauma.
Management: Patient in emergency with respiratory distress should be evaluated and managed according to the severity of the disturbance. Humidification and nebulization with steroids and bronchodilators improves the edema and swelling along with the respiratory distress.
If respiratory distress is not improved, the airway is secured, but not by endotracheal intubation as it may be difficult and hazardous, rather tracheostomy is done. Later when patient becomes stable in 3-4 days, open reduction of the fractures is done and mucosal tears are repaired by catgut. Normal anatomy is restored by repositioning of structures using various techniques by the ENT surgeon.
Broad spectrum antibiotics with good upper respiratory tract cover, like clarithromycin, amoxicillin or cephalosporin, are given to prevent perichondritis and cartilage necrosis.
Inflammations of Larynx
Acute inflammation of larynx can be infectious or non-infectious. Infection is usually viral initially, but soon, bacterial invasion occurs. Inflammation occurs producing fever, hoarseness, pain, or irritating cough, which is increased at night along with dry throat and malaise. Common bacteria are S. penumoiae, H. influenza, S. aureus and streptococci.
On laryngoscopy, initially, vocal cords show erythema and edema even in the epiglottis. Later, swelling becomes worse and redness increases, increasing the severity of the symptoms. Laryngitis secondary to diphtheria or tonsillitis is called acute membranous laryngitis.
Management: Nebulization with steam and steroids improves the edema. Voice rest and avoiding irritants like smoke along with cough suppressants and pain killers improves discomfort. If productive cough starts along with fever, antibiotic cover is given.
After recurrent infections of the larynx, vocal cords and surrounding structures become constantly inflamed. Repeated infections of the pharynx, exposure to dust, fumes, smoke, or vocal abuse can predispose to chronic inflammation. Patient usually complaints of hoarseness, dry cough, constant hawking and pain in throat. Local examination shows dull red, rounded vocal cords with viscid mucous around it.
Management: Avoiding irritants, voice rest, speech therapy, steam inhalation and expectorants are given to relieve the symptoms. Antibiotic cover is given for 7-10 days against the infection.
In smokers, usually in response to smoke exposure. It can lead to laryngitis.
Acute inflammation of the epiglottis and surrounding structures in the supraglottic space is more serious and sudden in onset than laryngitis, mostly affecting children of 2 – 7 years. H. influenza is the culprit in children. Patients present with dysphagia and sore throat along with dyspnea with or without stridor.
Examination of the oral cavity and laryngoscopy reveals edema and congestion of supraglottic structures. Physical examination is usually avoided as it may precipitate obstruction of the airway. It can be done in an ICU setup. Thumb sign on a neck x-ray (lateral view) confirms the diagnosis. Culture of the throat swab and blood culture can also be helpful.
Management: Hospitalization can be considered according to the severity of the disease. Antibiotics like ampicillin or third generation cephalosporin are effective against H. influenza. Dexamethasone or hydrocortisone is given to relieve edema and inflammation. Oxygen inhalation and nebulization along with increased hydration is recommended.
CROUP: Acute Laryngo-Tracheo-Bronchitis
Inflammation of the larynx, trachea and bronchi is mostly viral (Parainfluenza virus) affecting children up to 3 years. Patients complaint of flu-like symptoms and a characteristic barking cough with stridor.
Presence of the steeple sign supports a diagnosis of croup.
Management: Patient comes to emergency with barking cough. Nebulization with adrenaline, normal saline and bronchodilator is done to relieve the distress. After hospitalization, steroids like hydrocortisone are given along with antibiotics. Tracheostomy is considered if respiratory distress worsens.
Formation of pseudomembranes over the larynx, pharynx and tonsils is caused by infection of the C. diphtheriae. Its exotoxins can also cause myocarditis. Patient presents with sore throat, malaise, low grade fever, croupy cough, dyspnea and stridor. On examination, whitish membranes are observed over the throat and larynx. Lymphadenopathy leading to bull neck is characteristic of this disease.
Management: Complete bed rest with antibiotic cover and antitoxin treats the disease in 2-4 weeks. Benzyl penicillin is the antibiotic of choice. Diphtheria antitoxin 20,000 to 100,000 units I.V in normal saline drip for 5 days is recommended.
Other infections of the larynx secondary to diseases:
Larynx is infected in other disease states like tuberculosis, lupus erythmatosus, syphilis, leprosy and scleroderma.
Congenital Lesions of the Larynx
Excessive flaccidity of the supraglottic larynx which leads to sucked in position during inspiration thus producing stridor. This condition manifests at birth and disappears after 2 years of age. Laryngoscopy confirms the diagnosis.
Incomplete recanalization of the larynx produces congenital weak cry and airway obstruction. Thin webs can be cut through knife or CO2 laser. Thick webs need excision and placement of dilators.
This is the dilatation of the laryngeal saccule. It may be internal, external or combined. Treatment is excision through endoscopy.
Local Changes in the Larynx
Trauma to the vocal cords after vocal abuse or misuse leads to the formation of pin head to half pea sized nodules symmetrically on both cords. Edema and hemorrhage in the sub mucosal space become nodular after fibrosis.
These singer’s/screamer’s nodules can be managed conservatively by voice rest, speech therapy and education of the patients. Otherwise excision can be done under operating microscopy. Professional singers and people who have a lot of vocal demands are often affected by nodules.
Finger-like projections called polyps are often formed after vocal abuse or misuse mostly in adult and old age. It can also occur after some allergic response or smoking.
Patient presents with hoarseness; if the polyp is large, it can even lead to stridor or intermittent choking. It is managed by surgical excision followed by speech therapy.
Vocal misuse in which laryngeal cartilages rub against each other leads to ulceration and granuloma formation. Patients usually complain of hoarseness and discomfort in the throat. Ulcer is visible on the examination.
Granulomas are produced after prolonged endotracheal intubation or after injury to the vocal processes during intubation. Mucosal ulceration initially produced is followed by granuloma formation and produces hoarseness and even dyspnea. Voice rest and endoscopic removal is recommended.
Juvenile papillomas mostly occur in infants and children. These are usually viral in origin and multiple in number producing hoarseness and stridor. Local examination shows glistening white irregular growths, which may be pedunculated or sessile and bleed easily.
Management: Complete excision, cryotherapy, microelectrocautery, or CO2 laser are various treatment options.
Chondroma: Tumor of the Cartilages
Mostly cricoid cartilage is affected in chondroma producing dyspnea or even dysphagia.
Capillary type hemangiomas occur in infants, while cavernous types are common in adults.
Granular Cell Tumor
Mostly, it is submucosal and arises from the Schwann cells. It can differentiate into malignant tumor.
Laryngeal cancer is more common in males. Its incidence is increasing day by day due to the various risk factors. This malignant disease is seen in adult males after 40 years.
Various risk factors are:
- Alcohol use
- Air pollution
- Carcinogens exposure
- Radiation exposure
- Exposure to asbestos, mustard gas, petroleum products
Usually, a silent invasion occurs in the surrounding structures. Early metastasis occurs into the lymph nodes, more often into the upper and middle jugular lymph nodes.
Patient presents with throat pain, dysphagia, tender enlarged lymph nodes, and weight loss. Hoarseness is a late symptom.
Vocal cords become fixed due to tumor formation and hoarseness is produced, hence diagnosing the disease process earlier relative to other laryngeal cancers. Stridor may be produced after development of edema.
Usually rare, but it involves the structures below the glottis, even the trachea. Hoarseness is a late symptom. Metastasis occurs to the prelaryngeal, pretracheal and paratracheal lymph nodes.
Grade of Cancer
The grade of a cancer tells you how much the cancer cells look like normal cells under a microscope. There are 3 grades of laryngeal cancer:
- Grade 1 (low grade) – well differentiated
- Grade 2 (intermediate grade) – moderately differentiated
- Grade 3 (high grade) – poorly differentiated
TNM Stages of Cancer of the Larynx
TNM stands for Tumor, Node, and Metastasis. The system describes:
- The size of a primary tumor (T)
- Whether the lymph nodes have cancer cells in them (N)
- Whether the cancer has spread to a different part of the body (M)
American Joint Committee on Cancer gave the TNM classification of the laryngeal carcinoma:
T in TNM classification
- Tx – Primary tumor which cannot be assessed
- To – No evidence of primary tumor
- Tis – Carcinoma in situ
- T1 – Tumor less than or equal to 2 cm in greatest dimension
- T2 – Tumor greater than 2 cm in greatest dimension but < 4 cm
- T3 – Tumor greater than 4 cm in greatest dimension
- T4a – Moderatly advanced local disease
- T4b – Very advanced local disease
N stages of laryngeal cancer
There are 4 main lymph node stages in cancer of the larynx. N2 is divided into N2a, N2b and N2c. The important point here is presence or absence of cancer in any of the nodes, and in case of the former, the size and site of the involved lymph node.
- N0 – no lymph nodes containing cancer cells
- N1 – one lymph node involved on the same side of the neck with less than 3 cm size
- N2a – one lymph node on the same side of the neck, 3 cm – 6 cm size
- N2b – more than one lymph node, but none are more than 6 cm in greatest dimension; all the nodes must be on the same side of the neck as the cancer
- N2c – lymph nodes on the other side of the neck from the tumor or in nodes on both sides of the neck, but none is more than 6 cm
- N3 – at least one lymph node containing cancer larger than 6 cm size
M stages of laryngeal cancer
There are two stages to describe whether cancer of the larynx has spread:
- M0 – there is no cancer spread
- M1 – the cancer has spread to other parts of the body, such as the lungs
Diagnosing the Cancer
Hoarseness of 3 weeks and not improving is an important point in the history of the disease. Examination of the neck is important to find palpable lymph nodes. Following investigations need to be done:
Appearance of the lesion can be ulcerative (infrahyoid epiglottic involvement), exophytic (suprahyoid epiglottic involvement), or nodular (glottis).
Vocal cords may be fixed showing invasion or involvement of the recurrent laryngeal nerve.
- Chest x-ray to look for any associated lung disease and mediastinal lymph nodes
- CT scan or MRI for soft tissue lateral view of the neck
- Contrast laryngograms to confirm and measure the surface extent of the tumor
Treatment Options for Laryngeal Carcinoma
Radiotherapy is effective 70-90 % cure rate if…
- …cords are not fixed.
- …no subglottic extension.
- …cartilage is not involved.
- …no lymph node is involved.
- …no signs of invasion.
- Conservative surgery includes
- Cordectomy through a laryngofissure
- Partial frontolateral laryngectomy
- Partial horizontal laryngectomy (excision of supraglottis)
- Total laryngectomy: Block dissection is done along with laryngectomy.
It is done if:
- Fixed cords with a T3 stage tumor
- All T4 lesions
- Cartilages are involved
- Failure to cure the disease by radiotherapy or conservative surgery
- Tranglottic cancers which involves supraglottic and glottis
3. Combined Therapy
Combining the surgery with radiotherapy is also very effective. Radiation treatment before and after the surgery can decrease incidence of recurrence.
Vocal Rehabilitation after Treatment
Patients are taught to swallow air and keep it in the upper esophagus and slowly ejecting it. Rough voice is produced but patient can speak 6-10 words.
Electrolarynx is a device used to produce voice. Another device is called transoral pneumatic device which uses expired air from the tacheostome to vibrate the diaphragm and produce sound.
Vocal Cord Paresis
Paralysis of the vocal cords can be unilateral or bilateral due to the involvement of the nerves supplying the larynx, i.e recurrent laryngeal nerve, superficial laryngeal nerve.
1. Lesions in the nuclei of the nerves: Nucleus Ambigus in the medulla
Vascular disturbance or tumor compressing the medulla may also be a cause. Polio and syringomyelia can also involve larynx.
2. Higher lesions of the vagus nerve: in the skull or parapharyngeal space
Like tubercular meningitis, nasopharyngeal cancer, glomus tumor, metastatic lymph nodes, lymphoma.
3. Low vagal injury, i.e recurrent laryngeal nerve injury
4. Systemic causes, like syphilis, diabetes, diphtheria, viral infections
5. Idiopathic (30 % of the cases)
Causes of recurrent laryngeal nerve paralysis:
- Trauma to the neck
- Thyroid surgery
- Thyroid disease
- Thyroid cancer
- Cervical and mediastinal lymphadenopathy
- Esophageal cancer
- Enlarged left auricle
- Aortic aneurysm
Wagner and Grossman theory
It states that in complete paralysis of recurrent laryngeal nerve, the vocal cord lies in the paramedian position because the intact cricothyroid muscle adducts the cord (due to an intact superior laryngeal nerve). If the superior laryngeal nerve is also paralysed, the cord will assume an intermediate position because of the loss of adductive force.
Unilateral paralysis is usually asymptomatic; some patients may have voice problems, but issues regarding aspiration or airway obstruction are rare.
In bilateral paralysis, cords are in median or paramedian position. Airway is inadequate and dyspnea with or without stridor develops. Condition becomes worse on exertion.
Unilateral paralysis needs no treatment.
Patients with bilateral paralysis present in emergency and often need a tracheostomy. Later, either a permanent tracheostomy is done with a speaking valve, or surgery is done.
Surgical treatment: lateralization of the cord
- Thyroplasty type II
- Cordectomy with CO2 laser via encdoscopy
- Nerve muscle implant
Complete (combined) paralysis of the larynx:
If both the nerves supplying the cords are involved, complete paralysis of the cords occurs. Thyroid surgery is the most common cause. Patients presents with hoarseness of voice and aspiration of liquids.
Treatment includes speech therapy and surgically medialization of the cords through injection of Teflon paste or thyroplasty type I or anthrodesis of cricoarytenoid joint.
Popular Exam Questions on the Larynx
Solutions can be found below the references.
1. A child, 4 years old, presented to the emergency with an acute attack of severe cough and respiratory distress. While he was in the hospital, he also developed stridor. He has a history of sore throat for the last 2 days. On examination, supraglottic structures were edematous and congested. Which of the following most common causative agents in this disease is the child suffering from?
2. A child came to the family physician with hoarseness and respiratory difficulty along with flu-like symptoms. He was referred to an ENT surgeon who investigated the disease and did laryngeal endoscopy. Figure shows the larynx of the child. Child has history of chronic cough and noisy breathing.
- Chronic bronchitis
- Vocal cyst
- Squamous papilloma of larynx
Clinically Oriented Anatomy, 5th- by Keith L. Moore and Arthur F. Dalley
Diseases of ear, nose and throat, 5th edition by PL Dhingra, Shruti Dhingra
Robin and Cotran, Pathologic Basis of diseases 8th edition by Kumar and Abbas
Croup Treatment via NHS Choices
Resident Manual of Trauma to the Face, Head, and Neck via American Academy of Otolaryngology
Post-Laryngectomy Voice Rehabilitation via University of Missouri
Correct Answers: 1C, 2D