Some Neurological Disorders of Larynx for 3rd Year Medical Students

1. Sudeep Regmi
Vikash Sahani
14’ MBBS’’KUSMS
12th Feb, 2018

2. Nerve Supply of Larynx
Motor Supply
All intrinsic muscle : Recurrent Laryngeal Nerve
Except,
The Cricothyroid Muscle : External Laryngeal Nerve – the branch of
Superior Laryngeal nerve
Sensory Supply
Above the vocal cords: Internal Laryngeal Nerve – the branch of
Superior Laryngeal Nerve
Below the vocal cords: Recurrent Laryngeal Nerve
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3. Neurological Disorders of Larynx
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4. Recurrent Laryngeal Nerve
Right
 Arises from the Vagus, at the level of Subclavian
artery
 Hooks around it and
 Ascends between the trachea and oesophagus
Left
 Arises from Vagus in mediastinum
 At the level of arch of aorta
 Loops around it
 Then ascends into the neck in the trachea-
oesophageal groove.
Thus, Left recurrent laryngeal nerve has a much longer
course which make it more prone to paralysis
compared to the right one. ( About 75%)
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5. Superior Laryngeal Nerve
 Arises from inferior ganglion of the
Vagus
 Descends behind the internal carotid
artery
 At the level of greater cornua of hyoid
bone, divides into external and
internal branches
External Motor branch: Cricothyroid
muscle
Internal Sensory branch: Pierces
thyrohyoid membrane and supplies
sensory innervation to larynx and
hypopharynx.
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6. Classification of Laryngeal Paralysis
A. Incomplete paralysis
1. Recurrent laryngeal nerve palsy
 Left (75% )
 Right (15%)
 Bilateral (10%)
2. Superior laryngeal nerve palsy
B. Combined paralysis / complete paralysis
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7. Causes of Laryngeal Paralysis
 Supra-nuclear : rare
 Nuclear: Nucleus ambiguus in the medulla. vascular, neoplastic, motor,
neuron diseases, polio, syringobulbia.
 High vagal lesions: Combined palsy. Vagus involvement in the skull, at the
exit from juglar foramen, or in parapharyngeal space.
 Low vagal lesions: Recurrent laryngeal nerve palsy
 Systemic causes
 Idiopathic
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8. Recurrent
Laryngeal Nerve
Paralysis
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9. Etiology
Malignancy (25%): lung (>50%), thyroid, esophageal,
nasopharyngeal, metastatic neck node
Surgical trauma (20%): during surgeries of lung, heart, thyroid, esophagus,
mediastinum
Inflammatory (13%): tuberculosis, syphilis
Idiopathic (13%): viral neuritis
Non-surgical trauma (11%): accidental neck trauma,
left atrial enlargement, aortic aneurysm
Neurological (7%): CVA, head injury, Parkinsonism, multiple sclerosis,
alcoholic / diabetic neuropathy
Others (11%): rheumatoid arthritis, haemolytic anemia
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10. Unilateral RLN Palsy
Unilateral injury to recurrent laryngeal nerve results in ipsilateral paralysis
of all the intrinsic muscles except cricothyroid.
Causes of Right RLN Palsy
 Neck trauma
 Benign or malignant thyroid diseases
 Thyroid surgery
 Carcinoma of cervical oesophagus
 Cervical lymphadenopathy
 Aneurysm of subclavian artery
 Carcinoma apex of right lung
 Tuberculosis of cervical pleura
 Idiopathic
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Common
Recurrent
laryngeal nerve
palsy = Left
Common
Recurrent
Laryngeal Nerve
Palsy during
Tyroidoectomy =
Right

11. Causes of Left RLN Palsy
Neck
 Accidental trauma
 Thyroid diseases ( Benign or
Malignant)
 Thyroid surgeries
 Carcinoma cervical esophagus
 Cervical lymphadenopathy
Mediastinum
 Bronchogenic cancer (Most
Common)
 Carcinoma thoracic esophagus
 Aortic aneurysm
 Mediastinal lymphadenopathy
 Enlarged left auricle
 Intrathoracic surgeries
 idiopathic
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Bronchogenic carcinoma is an important cause of left recurrent paralysis and should
always be excluded by X-ray chest, bronchoscopy and biopsy unless the other causes
is obvious.

12. Incase of unilateral paralysis, the vocal cords assumes a median or paramedian
position and does not move laterally on deep inspiration.
There are many theories to explain the median or paramedian position of cord..
Semon’s Law
Rosenbach (1880) & Semon (1881)
“In all progressive organic lesions,
abductor fibres of recurrent laryngeal
nerve, which are phylogenetically
newer, are more susceptible and thus
first to be paralyzed compared to
adductor fibres.”
Wagner and Grossman hypothesis
In isolated paralysis of recurrent
laryngeal nerve, cricothyroid muscle
(which receives innervation from
superior laryngeal nerve) keeps vocal
cord in paramedian position due to
adductor function
In superior laryngeal nerve palsy, cord lies
in intermediate (cadaveric) position
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13. Position of
vocal cord
Distance from
center
Healthy Diseased
Median Midline Phonation RLN paralysis
Paramedian 1.5 mm Strong
whisper
RLN paralysis
Intermediate
(Cadaveric)
3.5 mm Neutral
position
Paralysis of both
RLN & SLN
Gentle
abduction
7 mm Quiet
respiration
Paralysis of
adductors
Full
abduction
9.5 mm Deep
inspiration
--
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Position of Vocal cord in Health and diseases

14. Clinical Features
 May pass undetected, as about one-third of patients are asymptomatic.
 Some changes in voice,
 But, no problems of aspiration or airways obstruction.
The voice in unilateral paralysis gradually improves due to compensation
by the healthy cord which cross the midline to meet the paralyzed one.
Treatment
 Generally, no treatment is required as compensation occurs. Temporary
paralysis recovers in 6 – 12 months.
 Injection of gelfoam or fat can be used to improve the voice in waiting
period.
 Laryngoplasty type I, if compensation does not take place
 Laryngoplasty type I with arytenoid adduction, if posterior glottis is
also incompetent
 Teflon injection, not preferred nowadays due to respiratory problems.
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15. Bilateral ( Bilateral Abductor Palsy)
Aetiology
Neuritis or surgical trauma ( thyroidectomy) are the important causes.
Position of cords
As all the intrinsic muscle of the larynx are paralyzed, the vocal cords
lie in median or paramedian position due to unopposed action of
cricothyroid muscle.
Clinical features
 Dyspnoea and stridor : as both the cords lie in median or paramedian
position, the airway is inadequate; worse on exertion or during an
attack of acute laryngitis.
 But, voice is not affected.
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16. Treatment
Tracheostomy
Many cases of bilateral abductor paralysis requires tracheostomy as an
emergency procedure, or when they develop upper respiratory tract
infections.
In long standing cases, the choice is between a permanent tracheostomy
with speaking vales or a surgical procedure to lateralize the cord.
The former relieves stridor, preserves good voice, but has the
disadvantage of tracheostomy hole in the neck;
While the latter relives airway obstruction but at the expenses of good
voice.
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17. Widening the respiratory airway without a permanent trachesotomy
( Endoscopic or through external cervical approach)
The aim is to widen the respiratory airway through larynx.
This can be achieved by
 Arytenoidectomy with suture
 Arytenoidopexy ( fixing the arytenoid in lateral position)
 Lateralization of vocal cords
And,
 Laser cordectomy ( removal of one cord)
However, these operations have now been replaced by less invasive
techniques, such as:
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18. 1. Transverse Cordotomy ( Kashima Operation)
Soft tissue at the junction of membranous cord and vocal process
of arytenoid is excised laterally with laser, which provides good airway.
2. Partial arytenoidectomy
Medial part of arytenoid is excised with laser. Sometimes only the
vocal process of arytenoid is ablated.
3. Reinnervation procedures
These have been used to innervate paralyzed posterior
cricoarytenoid muscle by implanting a nerve-muscle pedicle of sternohyoid
or omohyoid muscle with nerve supply from ansa hypoglossi.
4. Thyroplasty Type II
It creates lateral expansion of larynx and is similar to vocal cord
lateralization.
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19. Paralysis of Superior
Laryngeal Nerve
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20. Unilateral
Isolated lesions are rare, usually a part of combined paralysis.
Causes paralysis of cricothyroid muscle and ipsilateral anesthesia of the larynx
above the vocal cord.
Paralysis of cricothyroid can also occur when external laryngeal nerve is
involved in thyroid surgery, tumors, neuritis or diphtheria.
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During ligation of Superior thyroid vessels in thyroid surgeries, the
dissection should stay close to the thyroid to avoid nerve damage.
External branch of superior laryngeal nerve lies posteromedial to
the thyroid vessels and should be identified and preserved.

21. Clinical Features
Voice is weak and pitch cannot be raised.
Anaesthesia is unnoticed and occasional aspiration can occur.
Laryngeal findings include:
1. Askew position of glottis as anterior commissure is rotated to healthy side
2. Shorthening of cord with loss of tension
3. Flapping of paralysed cord
Cord sags down during inspiration and bulges up during expiration
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Electromyography of the cricoithyroid muscle helps to diagnose the
condition.

22. Bilateral
Uncommon condition
Both cricothyroid muscle paralysed along with anaesthesia of upper larynx
AETIOLGY
 Surgical or accidental trauma
 Neuritis(mostly diphtheritic)
 Pressure by cervical nodes
 Involvement in a neoplastic process
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23. Clinical Features
Inhalation of food and pharyngeal secretions giving rise to cough and chocking
fits.
Voice is weak and husky.
TREATMENT
Depends on cause
Neuritis may recover spontaneously
Tracheostomy with a cuffed tube for repeated aspiration and an oesophageal
feeding tube
Epiglottopexy is an operation to close the laryngeal inlet to protect lungs from
repeated aspiration. It is a reversible procedure.
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24. Combined(Complete)Paralysis
(Recurrent and Superior Laryngeal
Nerve Paralysis)
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25. Causes of Combined Paralysis(High Vagal)
 Intracranial Tumors of posterior fossa
Basal meningitis(tubercular)
 Skull base Fractures
Nasopharyngeal cancer
Glomus tumour
 Neck Penetrating injury
Parapharyngeal tumours
Metastatic nodes
Lymphoma
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26. Unilateral
Causes paralysis of all the muscles of larynx on one side except the
interarytenoid which also receives innervation from opposite side.
AETIOLOGY
 Thyroid surgery is the most common cause.
 Lesions of nucleus ambiguous or that of vagus proximal to origin of superior
laryngeal nerve
Lesion may lie in medulla, posterior cranial fossa, jugular foramen or
parapharyngeal space.
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27. Clinical Features
 Vocal cord lies in cadaveric position i.e. 3.5mm from the midline
 Glottic incompetence resulting in hoarseness of voice and aspiration of
liquids through the glottis
 Cough is ineffective due to air waste
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28. Treatment
1. Speech therapy
2. Procedures to medialize the cord
a) Injection of Teflon paste to paralyzed cord by direct laryngoscopy under
local anesthesia
b) Thyroplasty Type I It is done by creating a window in the thyroid cartilage
and placing a silicon or other prosthesis to medialize the cord.
c) Muscle or cartilage implant
d) Arthrodesis of cricoarytenoid joint
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29. Bilateral
Rare condition
Both cords lies in cadaveric position
Total anesthesia of the larynx
Clinical Features
1. Aphonia
2. Aspiration
3. Inability to cough
4. Bronchopneumonia
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30. Treatment
 Tracheostomy
 Epiglottopexy
 Vocal cord plication
Larynx is opened by laryngofissure. Mucosa of the true and false cord is
removed and approximated with sutures.
 Total laryngectomy
 Diversion procedures
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31. Congenital Vocal Cord
Paralysis
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32. Unilateral or bilateral condition
Though unilateral paralysis more common
Cause may be birth tauma or congenital anomaly of a great vessel or heart
Bilateral paralysis may be due
 Hydrocephalus
 Arnold-Chiari malformation
 Intracerebral haemorrhage during birth
 Meningocele
 Cerebral or nucleus ambiguus agenesis
Presents with features of bilateral abductor paralysis and respiratory
obstruction necessitating tracheostomy.
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33. Phonosurgery
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34. 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 paralysed cord so that opposite healthy cord easily
approximate.
3. Laryngeal reinnervation procedures
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 paralysed thyroarytenoid muscle
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35. Thyroplasty
Isshiki divided thyroplasty into 4 categories to produce functional alteration
of vocal cord.
a) Type I : medial displacement of vocal cord by Teflon paste injection
b) Type II : lateral displacement of vocal cord
c) Type III : shorten(relax) the vocal cord
It lowers pitch of voice, done in mutational falsetto or in those who have
gone gender transformation from female to male.
d) Type IV : lengthen(tighten) the vocal cord and elevate the pitch. It converts
male character of voice to female.
It is also used when vocal cord is lax and bowing due to aging process
on trauma.
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36. Neurological Disorders of Larynx
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Laryngismus stridulus ( Spasmodic
Laryngitis)
Also known as Pseudocroup/ Crowing inspiration/
Spasmodic croup
Spasmodic closure of glottis that lasts for few
seconds with cyanosis and inhalation accompanied
by crowing sound, usually seen in children at
night.

37. References
 Dhingra PL. Diseases of Ear, Nose and Throat & Head and Neck Surgery. 6th
Ed, 2014. Laryngeal Paralysis, 298 – 302.
 Hartl D M, Travagli JP, Leboulleux S, Baudin E, Schlumberger M. The Journal
of Clinical Endocrinology & Metabolism, Vol 90. Issue 5. Current Concept in
the Management of Unilateral Recurrent Laryngeal Nerve Paralysis after
Thyroid Surgery. Pages 3084 – 3088.
 www.wikipedia.com
 www.tbalu.com
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