Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_4407_Библиотеки_им_академика_М_И_Перельмана
.pdf
Page left intentionally blank
https://t.me/med1917
Chapter 60
https://t.me/med1917
Laryngeal Paralysis
NERVE SUPPLY OF LARYNX
Motor. All the muscles which move the vocal cord (abductors, adductors or tensors) are supplied by the recurrent laryngeal nerve except the cricothyroid muscle. The
latter receives its innervation from the external laryngeal
nerve—a branch of superior laryngeal nerve.
Sensory. Above the vocal cords, larynx is supplied by
internal laryngeal nerve—a branch of superior laryngeal,
and below the vocal cords by recurrent laryngeal nerve.
Recurrent laryngeal nerve. Right recurrent laryngeal
nerve arises from the vagus at the level of subclavian artery, hooks around it, and then ascends between the trachea and oesophagus. The left recurrent laryngeal nerve
arises from the vagus in the mediastinum at the level of
arch of aorta, loops around it, and then ascends into the
neck in the tracheo-oesophageal groove. Thus, left recurrent laryngeal nerve has a much longer course which
makes it more prone to paralysis compared to the right
one (Figure 60.1 ).
Superior laryngeal nerve. It arises from inferior ganglion of the vagus, descends behind internal carotid artery and, at the level of greater cornua of hyoid bone,
divides into external and internal branches. The external
branch supplies cricothyroid muscle while the internal
branch pierces the thyrohyoid membrane and supplies
sensory innervation to the larynx and hypopharynx.
3. High vagal lesions. Vagus nerve may be involved
intracranially, at the exit from the jugular foramen or
in the parapharyngeal space (Table 60.1).
4. Low vagal or recurrent laryngeal nerve (Table 60.2).
5. Systemic causes. Diabetes, syphilis, diphtheria, typhoid,
streptococcal or viral infections, lead poisoning.
6. Idiopathic. In about 30% of cases, cause remains
obscure.
RECURRENT LARYNGEAL NERVE
PARALYSIS
A. UNILATERAL
Unilateral injury to recurrent laryngeal nerve results in
ipsilateral paralysis of all the intrinsic muscles except
the cricothyroid. The vocal cord thus assumes a median
or paramedian position and does not move laterally on
deep inspiration (Table 60.2). There are many theories to
explain the median or paramedian position of the cord.
One is Semon’s law which states that, in all the progressive
CLASSIFICATION OF LARYNGEAL
PARALYSIS
Laryngeal paralysis may be unilateral or bilateral, and
may involve:
1. Recurrent laryngeal nerve.
2. Superior laryngeal nerve.
3. Both recurrent and superior laryngeal nerves (combined or complete paralysis).
CAUSES OF LARYNGEAL PARALYSIS
In topographical manner, the causes are:
1. Supranuclear. Rare.
2. Nuclear. There is involvement of nucleus ambiguus in
the medulla. The causes are vascular, neoplastic, motor
neurone disease, polio and syringobulbia. In nuclear
lesions, there would be associated paralysis of other
cranial nerves and neural pathways.
Figure 60.1. Recurrent and superior laryngeal nerves.
Scan to play Laryngeal Paralysis.
337
338
https://t.me/med1917
SECTION V — Diseases of Larynx and Trachea
organic lesions, abductor fibres of the nerve, which are
phylogenetically newer, are more susceptible and thus
the first to be paralyzed compared to adductor fibres.
The other explanation is Wagner and Grossman hypoth-
esis which states that cricothyroid muscle which receives
innervation from superior laryngeal nerve keeps the cord
in paramedian position due to its adductor function.
The aetiology of recurrent laryngeal nerve paralysis is
given in Table 60.3. Bronchogenic carcinoma is an impor-
tant cause of left recurrent paralysis and should always be
excluded by X-ray chest, bronchoscopy and biopsy unless
the other cause is obvious.
Clinical Features
Unilateral recurrent laryngeal paralysis may pass undetected as about one-third of the patients are asymptomatic. Others have some change in voice but no problems of
TABLE 60.1 CAUSES OF COMBINED PARALYSIS
(HIGH VAGAL LESIONS)
Intracranial • Tumoursofposteriorfossa
• Basalmeningitis(tubercular)
Skull base • Fractures
• Nasopharyngealcancer
• Glomustumour
Neck • Penetratinginjury
• Parapharyngealtumours
• Metastaticnodes
• Lymphoma
aspiration or airway obstruction. The voice in unilateral
paralysis gradually improves due to compensation by the
healthy cord which crosses the midline to meet the paralyzed one.
Treatment
1. Generally no treatment is required as compensation
occurs due to opposite healthy cord. Temporary paralysis recovers in 6–12 months and it is advisable to
wait. However injection of gelfoam or fat can be used
to improve the voice in the waiting period.
2. Laryngoplasty type I can be used if compensation does
not take place.
3. Laryngoplasty type I with arytenoid adduction is done
if posterior glottis is also incompetent.
4. Teflon injection has been used in the past to medialize
the cord permanently but is not favoured these days.
B. BILATERAL (BILATERAL ABDUCTOR
PARALYSIS)
Aetiology
Neuritis or surgical trauma (thyroidectomy) are the most
important causes. The condition is often acute.
Position of Cords
As all the intrinsic muscles of larynx are paralyzed, the
vocal cords lie in median or paramedian position due to
unopposed action of cricothyroid muscles (Figure 60.2).
TABLE 60.2 POSITION OF THE VOCAL CORD IN HEALTH AND DISEASE
Situation in
Position of the cord Location of the cord from midline Health Disease
Median Midline Phonation RLN paralysis
Paramedian 1.5 mm Strong whisper RLN paralysis
Intermediate (cadaveric) 3.5 mm. This is neutral position of cricoarytenoid
joint. Abduction and adduction take place from
this position
Gentle abduction 7 mm Quiet respiration Paralysis of adductors
Full abduction 9.5 mm Deep inspiration —
— Paralysis of both recurrent and
superior laryngeal nerves
TABLE 60.3 CAUSES OF RECURRENT LARYNGEAL NERVE PARALYSIS (LOW VAGAL TRUNK OR RECURRENT
LARYNGEAL NERVE)
Right Left Both
• Necktrauma I. Neck
• Benignormalignantthyroiddisease • Accidentaltrauma
• Thyroidsurgery • Thyroiddisease(benignormalignant) • Thyroidsurgery
• Carcinomacervicaloesophagus • Thyroidsurgery • Carcinomathyroid
• Cervicallymphadenopathy • Carcinomacervicaloesophagus • Cancercervicaloesophagus
• Cervicallymphadenopathy • Cervicallymphadenopathy
II. Mediastinum
• Aneurysmofsubclavianartery • Bronchogeniccancer
• Carcinomaapexrightlung • Carcinomathoracicoesophagus
• Tuberculosisofcervicalpleura • Aorticaneurysm
• Idiopathic • Mediastinallymphadenopathy
• Enlargedleftauricle
• Intrathoracicsurgery
• Idiopathic
Figure 60.2. Position of vocal cords.
https://t.me/med1917
Clinical Features
As both the cords lie in median or paramedian position,
the airway is inadequate causing dyspnoea and stridor but
the voice is good. Dyspnoea and stridor become worse on
exertion or during an attack of acute laryngitis.
Treatment
Tracheostomy. Many cases of bilateral abductor paralysis require tracheostomy as an emergency procedure or
when they develop upper respiratory tract infection.
In long-standing cases, the choice is between a permanent tracheostomy with a speaking valve or a surgical
procedure to lateralize the cord. The former relieves stridor, preserves good voice but has the disadvantage of a
tracheostomy hole in the neck. The latter relieves airway
obstruction but at the expense of a good voice; however,
there is no tracheostomy hole in the neck.
Widening the respiratory airway without a permanent tracheostomy (endoscopic or through external
cervical approach). Aim is to widen the respiratory air-
way through larynx. This can be achieved by (i) arytenoidectomy with suture, (ii) arytenoidopexy (fixing the
arytenoid in lateral position), (iii) lateralization of vocal
cord and (iv) laser cordectomy (removal of one cord).
These operations have now been replaced by less invasive
techniques such as:
1. Transverse cordotomy (Kashima operation). Soft tissue
at the junction of membranous cord and vocal pro-
cess of arytenoid is excised laterally with laser. This
provides good airway. In case airway is still insuf-
ficient more tissue can be removed at subsequent
operation.
2. Partial arytenoidectomy. Medial part of arytenoid is ex-
cised with laser. Sometimes only the vocal process of
arytenoid is ablated.
3. Reinnervation procedures. These have been used to in-
nervate paralyzed posterior cricoarytenoid muscle
Chapter 60 — Laryngeal Paralysis
by implanting a nerve–muscle pedicle of sternohyoid or omohyoid muscle with its nerve supply from
ansa hypoglossi. These procedures have not been very
successful.
4. Thyroplasty type II. It creates lateral expansion of larynx
and is similar to vocal cord lateralization. Quality of
voice may not be good.
339
PARALYSIS OF SUPERIOR
LARYNGEAL NERVE
A. UNILATERAL
Isolated lesions of this nerve are rare; usually, it is a part of
combined paralysis. Paralysis of superior laryngeal nerve
causes paralysis of cricothyroid muscle and ipsilateral
anaesthesia of the larynx above the vocal cord. Paralysis
of cricothyroid can also occur when external laryngeal
nerve is involved in thyroid surgery, tumours, neuritis or
diphtheria.
Clinical Features
Voice is weak and pitch cannot be raised with decreased
ability to sing. Anaesthesia of the larynx on one side may
pass unnoticed or cause occasional aspiration. Laryngeal
findings include:
1. Askew position of glottis as anterior commissure is rotated to the healthy side.
2. Shortening of cord with loss of tension. The paralyzed
cord appears wavy due to lack of tension.
3. Flapping of the paralyzed cord. As tension of the cord
is lost, it sags down during inspiration and bulges up
during expiration.
4. Electromyography of the cricothyroid muscle helps to
diagnose the condition.
B. BILATERAL
This is an uncommon condition. Both the cricothyroid
muscles are paralyzed along with anaesthesia of upper
larynx.
Aetiology
Important causes include surgical or accidental trauma,
neuritis (mostly diphtheritic), pressure by cervical nodes
or involvement in a neoplastic process.
Clinical Features
Presence of both paralysis and bilateral anaesthesia causes
inhalation of food and pharyngeal secretions giving rise
to cough and choking fits. Voice is weak and husky.
Treatment
It depends on the cause. Cases due to neuritis may recover spontaneously. Patients with repeated aspiration may
require tracheostomy with a cuffed tube and an oesophageal feeding tube.
Epiglottopexy is an operation to close the laryngeal in-
let to protect the lungs from repeated aspiration. It is a
reversible procedure.
340
https://t.me/med1917
SECTION V — Diseases of Larynx and Trachea
COMBINED (COMPLETE) PARALYSIS
(RECURRENT AND SUPERIOR LARYNGEAL
NERVE PARALYSIS)
A. UNILATERAL
This causes paralysis of all the muscles of larynx on one
side except the interarytenoid which also receives innervation from the opposite side.
Aetiology
Thyroid surgery is the most common cause when both
recurrent and external laryngeal nerves of one side may
be involved.
It may also occur in lesions of nucleus ambiguus or
that of the vagus nerve proximal to the origin of superior
laryngeal nerve. Thus, lesion may lie in the medulla, posterior cranial fossa, jugular foramen or parapharyngeal
space (Table 60.1).
Clinical Features
As all the muscles of larynx on one side are paralyzed,
vocal cord will lie in the cadaveric position, i.e. 3.5 mm
from the midline (Table 60.2). The healthy cord is unable
to approximate the paralyzed cord, thus causing glottic
incompetence. This results in hoarseness of voice and aspiration of liquids through the glottis. Cough is ineffective due to air waste.
Treatment
1. Speech therapy. With proper speech therapy, the
healthy cord may compensate the loss of function of
paralyzed vocal cord by moving across the midline.
2. Procedures to medialize the cord. In uncompensat-
ed cases, aim is to bring the paralyzed cord towards
the midline so that healthy cord can meet it. This is
achieved by:
(a) Injection of teflon paste lateral to the paralyzed cord.
This is done by direct laryngoscopy under local
anaesthesia. Now thyroplasty is the preferred
procedure.
(b) Thyroplasty type I. Vocal cord is medialized towards
midline for opposite cord to meet. This can be
combined with arytenoids adduction procedure.
Thyroplasty is done by creating a window in the
thyroid cartilage and placing a silicon or other
prosthesis to medialize the cord. Operation can be
done under local anaesthesia.
B. BILATERAL
Both recurrent and superior laryngeal nerves on both
sides are paralyzed. This is a rare condition. As all the
laryngeal muscles are paralyzed, both cords lie in cadaveric position. There is also total anaesthesia of the
larynx.
Clinical Features
1. Aphonia. As cords do not meet at all.
2. Aspiration. This is due to incompetent glottis and la-
ryngeal anaesthesia.
3. Inability to cough. This is due to inability of the cords
to meet. This results in retention of secretions in the
chest.
4. Bronchopneumonia. This is due to repeated aspirations and retention of secretions.
Treatment
1. Tracheostomy. Essential to remove pulmonary secre-
tions and inhaled material.
2. Gastrostomy. It will prevent aspiration and maintain
nutrition.
3. Epiglottopexy. It is an operation in which epiglottis
is folded backwards and fixed to the arytenoids so as
to prevent aspiration into the lungs. It is a reversible
procedure.
4. Vocal cord plication. Larynx is opened by laryngofis-
sure. Mucosa of the true and false cords is removed and
then they are approximated with sutures. This procedure helps to prevent aspiration and can be reversed
when required.
5. Total laryngectomy. May be needed in those where
cause is progressive and irreversible and speech is unserviceable. Laryngectomy will prevent repeated aspiration and lung infections.
6. Diversion procedures. Trachea is separated at third or
fourth rings and its upper segment (laryngotracheal)
is anastomosed to oesophagus while the lower end is
brought out as tracheostome for breathing. Aspirated
material now finds its way to oesophagus. This operation is done in intractable aspiration.
CONGENITAL VOCAL CORD PARALYSIS
It may be unilateral or bilateral. Unilateral paralysis is
more common. The cause may be birth trauma or congenital anomaly of a great vessel or heart. Bilateral paralysis may be due to hydrocephalus or Arnold–Chiari
malformation, intracerebral haemorrhage during birth,
meningocele, or cerebral or nucleus ambiguus agenesis.
The patient of bilateral paralysis presents with features
of bilateral abductor paralysis and respiratory obstruction
necessitating tracheostomy.
PHONOSURGERY
Several surgical procedures have been designed to improve the quality of voice. They include:
1. Excision of benign or malignant lesions by microlaryngeal surgery or laser.
2. Injection of vocal cord with teflon paste or gelfoam to
augment and medialize the paralyzed cord so that the
opposite healthy cord can easily approximate.
3. Thyroplasty. Isshiki divided thyroplasty procedures
into four categories to produce functional alteration of
vocal cords.
achieved in teflon paste injection.
(b) Type II. It is lateral displacement of vocal cord and
is used to improve the airway.
Chapter 60 — Laryngeal Paralysis
https://t.me/med1917
341
(c) Type III. It is used to shorten (relax) the vocal cord.
Relaxation of vocal cord lowers the pitch. This procedure is done in mutational falsetto or in those
who have undergone gender transformation from
female to male.
(d) Type IV. This procedure is used to lengthen (tighten)
the vocal cord and elevate the pitch. It converts
male character of voice to female and has been
used in gender transformation. It is also used when
vocal cord is lax and bowing due to aging process
or trauma.
4. Laryngeal reinnervation procedures. In this, a segment
of anterior belly of omohyoid muscle, carrying its
nerve (ansa hypoglossi) and vessels, is implanted into
the thyroarytenoid muscle after making a window in
thyroid cartilage. It is supposed to innervate the paralyzed thyroarytenoid muscle.
Page left intentionally blank
https://t.me/med1917
Chapter 61
https://t.me/med1917
Benign Tumours of Larynx
Benign tumours of the larynx are not as common as the
malignant ones. They are divided into: (i) non-neoplastic
and (ii) neoplastic (Table 61.1 ).
NON-NEOPLASTIC TUMOURS
They are not true neoplasms but are tumour-like masses
which form as a result of infection, trauma or degeneration. They are seen more frequently than true benign
neoplasms. They are further divided into solid and cystic.
A. SOLID NON-NEOPLASTIC LESIONS
1. Vocal nodules (Singer’s or Screamer’s nodes)
They appear symmetrically on the free edge of vocal cord,
at the junction of anterior one-third, with the posterior
two-thirds, as this is the area of maximum vibration of the
cord and thus subject to maximum trauma (Figures 61.1
and 61.2). Their size varies from that of pin-head to half
a pea. They are the result of vocal trauma when person
speaks in unnatural low tones for prolonged periods or at
high intensities. They mostly affect teachers, actors, vendors or pop singers. They are also seen in school going
children who are too assertive and talkative.
Pathologically, trauma to the vocal cord in the form of
vocal abuse or misuse causes oedema and haemorrhage in
the submucosal space. This undergoes hyalinization and
fibrosis. The overlying epithelium also undergoes hyperplasia forming a nodule. In the early stages, the nodules
appear soft, reddish and oedematous swellings but later
they become greyish or white in colour.
Patients with vocal nodules complain of hoarseness.
Vocal fatigue and pain in the neck on prolonged phonation are other common symptoms.
Early cases of vocal nodules can be treated conservatively by educating the patient in proper use of voice.
With this treatment, many nodules in children disappear completely. Surgery is required for large nodules or
nodules of long standing in adults. They are excised with
precision under operating microscope either with cold instruments or laser avoiding any trauma to the underlying
vocal ligament (Figure 61.3).
Speech therapy and re-education in voice production
are essential to prevent their recurrence.
2. Vocal polyp
It is also the result of vocal abuse or misuse. Other contributing factors are allergy and smoking. Mostly, it affects men in the age group of 30–50 years. Typically, a
vocal polyp is unilateral arising from the same position
Figure 61.1. Vocal nodules. Typically, they form at the junction of
anterior one-third with posterior two-thirds of vocal cord.
TABLE 61.1 BENIGN TUMOURS OF LARYNX
Non-neoplastic Neoplastic
Solid
• Vocal nodules
• Vocal polyp
• Reinke’s oedema
• Contact ulcer/granuloma
• Intubation granuloma
• Leukoplakia
• Amyloid tumours
Cystic
• Ductal cysts
• Saccular cysts
• Laryngocele
Scan to play Benign Tumours of Larynx.
Squamous papilloma
• Juvenile type
• Adult-onset type
Chondroma
Haemangioma
Granular cell tumours
Glandular tumours, e.g.
• Pleomorphic adenoma
• Oncocytoma
Neurilemmoma
Rhabdomyoma
Lipoma
Fibroma
Figure 61.2. Vocal nodules.
343
344
https://t.me/med1917
SECTION V — Diseases of Larynx and Trachea
Figure 61.3. Note the set up for microlaryngeal surgery.
4. Contact ulcer or granuloma
This is again due to faulty voice production in which vocal processes of arytenoids hammer against each other
resulting in ulceration and granuloma formation. Some
cases are due to gastric reflux. Chief complaints are hoarse
voice, a constant desire to clear the throat and pain in
the throat which is worse on phonation. Examination reveals unilateral or bilateral ulcers on the vocal processes
of arytenoids with mucosal congestion over the arytenoid
cartilages. There may be granuloma formation.
Management consists of
(a) Antireflux therapy.
(b) Speech therapy to stop throat clearing and correct the
pitch of voice.
(c) Inhaled steroids or intralesional injection of steroid
to correct inflammation and size of granuloma.
Microlaryngeal surgery may be needed to remove
granuloma.
5. Intubation granuloma
It results from injury to vocal processes of arytenoids due
to rough intubation, use of large tube or prolonged presence of tube between the cords. Mucosal ulceration is
followed by granuloma formation over the exposed cartilage. Usually, they are bilateral involving posterior thirds
of true cords. They present with hoarseness and if large,
dyspnoea as well. Treatment is voice rest and endoscopic
removal of the granuloma.
Figure 61.4. Sessile vocal polyp on the left cord.
as vocal nodule (Figure 61.4). It is soft, smooth and often
pedunculated. It may flop up and down the glottis during
respiration or phonation. Hoarseness is a common symptom. Large polyp may cause dyspnoea, stridor or intermittent choking. Some patients complain of diplophonia
(double voice) due to different vibratory frequencies of
the two vocal cords.
Vocal polyp is caused by sudden shouting resulting in
haemorrhage in the vocal cord and subsequent submucosal oedema. Treatment is surgical excision under operating microscope followed by speech therapy.
3. Reinke’s oedema (bilateral
diffuse polyposis)
This is due to collection of oedema fluid in the subepithelial space of Reinke. Usual cause is vocal abuse and smoking.
Both vocal cords show diffuse symmetrical swellings.
Treatment is longitudinal incision in the cord and removal
of gelatinous fluid. Re-education in voice production and
cessation of smoking are essential to prevent recurrence.
6. Leukoplakia or keratosis
This is also a localized form of epithelial hyperplasia
involving upper surface of one or both vocal cords. It
appears as a white plaque or warty growth on the cord
without affecting its mobility. It is regarded as a precancerous condition because “carcinoma in situ” frequently
supervenes. Hoarseness is the common presenting symptom. Treatment is stripping of vocal cords and subjecting the tissues to histology for any malignant change.
Chronic laryngeal irritants as the aetiological factors
should be sought and eliminated.
7. Amyloid tumour
It mostly affects men in the age group of 50–70 years.
Amyloid deposits involve vocal cord, ventricular band,
subglottic area or trachea. It presents as a submucosal
mass. Presenting symptoms are hoarseness or breathing
difficulty. Systemic disease like multiple myeloma should
be excluded. Diagnosis is made on biopsy and special
staining. Treatment of localized deposits is by surgical removal. Prognosis is good.
B. CYSTIC LESIONS
They are of three types:
1. Ductal cysts. Most often they are retention cysts
due to blockage of ducts of seromucinous glands of laryngeal mucosa. They are seen in the vallecula, aryepiglottic fold, false cords, ventricles and pyriform fossa. They
may remain asymptomatic if small, or cause hoarseness,
cough, throat pain and dyspnoea, if large (Figure 61.5).
Sometimes, an intracordal cyst may occur on the true
cord. It is similar to an epidermoid inclusion cyst.
Figure 61.5. (A) Aryepiglottic cyst. It caused intermittent laryngeal
https://t.me/med1917
obstruction. (B) Cyst after removal.
2. Saccular cysts. Obstruction to the orifice of saccule
causes retention of secretion and distension of saccule
which presents as a cyst in laryngeal ventricle. Anterior
saccular cysts present in the anterior part of ventricle and
obscure part of vocal cord. Lateral saccular cysts, which are
larger, extend into the false cord, aryepiglottic fold and
may even appear in the neck through thyrohyoid membrane just as laryngoceles do.
3. Laryngocele. It is an air-filled cystic swelling due
to dilatation of the saccule (Figure 61.6). A laryngocele
may be:
(a) Internal which is confined within the larynx and pre-
sents as distension of false cord and aryepiglottic fold.
(b) External in which distended saccule herniates through
the thyroid membrane and presents in neck.
(c) Combined or mixed in which both internal and exter-
nal components are seen.
Figure 61.6. Laryngocele mixed type with internal and external
components.
Chapter 61 — Benign Tumours of Larynx
Figure 61.7. Laryngocele left side as seen on Valsalva (arrow).
A laryngocele is supposed to arise from raised transglottic air pressure as in trumpet players, glass-blowers or
weight lifters.
A laryngocele presents with hoarseness, cough and
if large, obstruction to the airway. An external laryngocele presents as a reducible swelling in the neck which
increases in size on coughing or performing Valsalva
(Figure 61.7).
Diagnosis can be made by indirect laryngoscopy, and
soft tissue AP and lateral views of neck with Valsalva. CT
scan helps to find the extent of lesion.
Treatment is surgical excision through an external
neck incision. Marsupialization of an internal laryngocele
can be done by laryngoscopy but there are chances of recurrence.
A laryngocele in an adult may be associated with carcinoma which causes obstruction of saccule.
345
NEOPLASTIC
Except for laryngeal papillomas which constitute about
80% of the total occurrence of neoplasms of the larynx,
others are uncommon.
A. SQUAMOUS PAPILLOMAS
They can be divided into (i) juvenile and (ii) adult-onset
types.
1. Juvenile papillomatosis (Syn. respiratory
papillomatosis)
Juvenile papillomatosis is the most common benign neoplasm of the larynx in children. It is viral in origin and is
caused by human papilloma DNA virus type 6 and 11. It
is presumed that affected children got the disease at birth
from their mothers who had vaginal human papilloma
virus disease.
Papillomas mostly affect supraglottic and glottic regions of larynx but can also involve subglottis, trachea
and bronchi (Figure 61.8). Children who had tracheostomy for respiratory distress due to laryngeal papillomas
have higher incidence of tracheal and stomal involvement due to seeding. DNA virus particles have been
found in the cells of basement membrane of respiratory
mucosa and may account for widespread involvement
and recurrence.
Соседние файлы в папке Библиотека им академика М.И. Перельмана