Bilateral Recurrent Laryngeal Nerve Injury
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Etiology
This syndrome results from an injury to both recurrent laryngeal nerves. It affects all of the intrinsic laryngeal muscles (thyroarytenoid, lateral cricoarytenoid, posterior cricoarytenoid, interarytenoid) except the cricothyroid. There may be varying degrees of paralysis (which is used in the sense of "motion impairment") since the injury may be (and almost always is) incomplete. Reinnervation usually occurs as reinnervation with synkinesis. This disordered reinnervation usually causes isotonic contraction rather than functional contraction and movement. In my experience, reinnervation with synkinesis is common.

Diagnosis
History
Typical complaints
• onset
o abrupt initial loss of voice after surgery is the most typical presentation
 total thyroidectomy
 parathyroidectomy
o This weak voice is usually associated with choking on liquids
• weak voice for several months initially
• Later, the voice becomes “Mickey Mouse” like for a few weeks.
• Then the voice improves becoming nearly normal
• Or the voice may become somewhat unpredictable with unusual sounds coming out at strange times.
• Breathing difficulty: Variable in onset, but typically 3 to 4 months post injury, breathing becomes tight with any exercise
• laryngospasms - Episodes where one cannot breath easily, high pitched sounds while trying to breath.
o perfumes, odors or drinking may trigger episodes
• Frequently very noisy breathers at night. Increased snoring.
Character of a patient with Bilateral Recurrent Laryngeal Nerve Injury
• poor voice early in illness
• often accepting of the surgeons recommendation to just wait and see for six months to a year
• often excellent voice late in recovery phase
• or a voice that is good but fades with use
• Talkativeness scale: whole range
Vocal capabilities
These findings will depend a great deal on when in the time course of the illness the patient presents for an exam.
• Speaking voice
o Early: whisper
o Late: clear but some sounds seem out of direct control of the patient
• Yelling voice
o Early: luffing sound (asynchronous vibration like a sail flapping in the wind) on loud phonation at low pitch early
o Late: good shout later in recovery
• Maximum phonation time
o Early: markedly reduced at anchor pitch (often less than 1 to 3 seconds)
o Late: normal
• Pitch range
o obligate falsetto (physical inability to phonate in other than falsetto register) This is the “Mickey Mouse” phase. This is the opposite of a superior laryngeal nerve injury where the thyroarytenoid (TA) and lateral cricoarytenoid (LCA) muscles provide tension at low pitch but the cricothyroid is unable to provide additional tension to raise the pitch. Here the cricothryoid is the main muscle helping to approximate the vocal folds.
• Vegetative sounds - cough
o Early: nonpercussive cough
o Late: may sound like a sick dog or barking seal later as the vocal cords fail to relax after initial closure
Laryngeal Exam
• rigid laryngoscope
o may be in paramedian or lateralized position early
o complete immobility early
o decreased range of motion also possible
 because Interarytenoid may actively pull the affected side somewhat
 injury may be incomplete involving only a portion of the posterior or anterior branches of the recurrent laryngeal nerve
 reinnervation may be taking place
o almost essential to use video recording to slow down and analyze the motion of the arytenoids that is taking place
o bowing
• flexible laryngoscope
o motion may range from scant to obvious attempts at closure
o after about a month there may be bilateral atrophy or noodle like vocal folds
o Capacious ventricle on the both sides
o Conus may also show some tissue loss
o abnormal configuration of posterior glottis even if vocal processes oppose each other
o some movement may make it difficult to separate out fixation form paralysis visually
o if the patients are followed over time:
 If severely injured, the vocal processes will gradually assume a resting position 1 to 3 mm apart. The less injured they are, the further will be their range of ABduction.
 They may actively ADduct during sniffing (synkinesis).
 with deep or rapid inspiration, the membranous portion of the vocal cords may pull medially because of their proximity and Bernoulli's effect.
• Laryngeal EMG (electromyogram) can be used to assess which muscles are denervated and whether synkinesis is present though it is a bit of a tedious and uncomfortable exam and requires a lot of interpretation.
• One of the most important issues for the diagnostician is to differentiate between fixation of the vocal cords from scarring versus vocal paresis and paralysis.
Treatment

This will depend on where in the time course of the injury and recovery the patient is.
Medical
• Botox injections
o botulinum toxin injections can be useful in two different ways
 injecting the TA or the LCA muscles can lead to opening of the airway and better breathing
 the same injection can be used diagnostically as the amount of opening or ABduction that you get with a Botox injection into both sides can be used to compare which side has the largest potential range of motion
o On the downside, since there are typically fewer motor units after an injury, the patient may be very sensitive to small changes in dosage having larger ranges of effect.
Behavioral
• Early, just using the voice is appropriate as this provides some stimulation to any of the muscles that have residual innervation
• tipping the chin down or to the side can improve the swallowing of liquids during the early phase when the vocal cords are far apart
Surgical
• Medialization (temporary) with an in office injection early in the injury.
o Collagen
 Human collagen Cymetra by LifeCell Corporation
 Bovine collagen Zyplast by Mcghan Pharmaceuticals
 Patient information on injections
o Radiesse - possibly useful, though it may be too long lasting. One might consider Radiesse gel.
o Gelfoam - I haven't used this for years because of its short duration and difficulty mixing and injecting
• Late in the injury when both vocal folds are together
o multiple options, each with varying degrees of compromise between quality of voice and volume of air. The most important thing for the physician is to view the ADduction and ABduction of the vocal cords closely and see which one moves the most appropriately and through the greatest range of motion and then if using a destructive procedure, work on the one that is most fixated
 Tracheotomy - this can be done alone and is "curative" in that there is an adequate airway via the tracheotomy, and there is excellent voice via the vocal cords with the tracheotomy plugged. However, there is a device and hole in the neck that needs to be maintained for a lifetime and swimming is no longer an option with a hole in the neck
 Laser arytenoidectomy
 Laser cordotomy
 Often a temporary tracheostomy is done with the above procedures while waiting for post-surgical swelling to resolve.
 Arytenoid lateralization via suture with accompanying medialization of the membranous portion of the vocal cord to improve airway while maintaining some voice.
 Selective denervation of the anterior branch of the recurrent laryngeal nerve
o None of these options are perfect, though with care, many times a good balance can be reached between vocal volume and ease of breathing. I use different combinations of the above procedures depending on the patient's needs, the degree of weakness, the degree of synkinesis and how long it has been since the injury.
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RECURRENT LARYNGEAL NERVE INJURY: AN EXPERIENCE WITH 310 THYROIDECTOMIES
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http://www.ayubmed.edu.pk/JAMC/PAST/...aq%20Ahmed.pdf

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