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Thread: Unilateral Recurrent Laryngeal Nerve Injury

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    Arrow Unilateral Recurrent Laryngeal Nerve Injury

    Unilateral Recurrent Laryngeal Nerve Injury

    Etiology
    This syndrome results from an injury to the recurrent laryngeal nerve. It may affect all, one or several of the intrinsic laryngeal muscles (thyroarytenoid, lateral cricoarytenoid, posterior cricoarytenoid, interarytenoid) except the cricothyroid. There may be varying degrees of paresis since the injury may be incomplete, reinnervation may occur or reinnervation with synkinesis may occur. This disordered reinnervation may cause isotonic contraction rather than functional contraction and movement.
    Diagnosis
    History

    Typical complaints

    • onset
    o abrupt laryngitis if problem started after surgery or viral illness
     thyroid surgery
     carotid artery or vascular
     Anterior cervical fusion or other neck surgery approached from the front.
     chest or heart surgery may in particular injure the left side
    o gradual laryngitis if problem starts from tumor involving the path of the recurrent laryngeal nerve
     skull base
     neck
     thyroid
     lung
    • weak voice
    • Endurance is diminished (the patient may report a voice that functions for them for two to eight hours rather than a full day. They are using the cricothyroids to provide a some tension on the paralysed fold such that it will vibrate at a speaking pitch and this causes fatigue.)
    • cannot compete with background noise
    • trouble swallowing or choking on liquids
    • unable to sing
    • speaking pitch too high
    • Subtleties
    o This tends to be a disorder that is often just subclinical in its symptoms. The injured person gets along, but certain things suddenly tip the scale. The paralyzed cord is just barely compensating and a respiratory infection (cold) results in weeks of laryngitis instead of days. Loud talking makes the voice give out so the person habitually avoids background noise and talking loudly and never has trouble, then one day overuses the voice and is hoarse for a prolonged period afterwards. The thin or weak cord has been nursed along by the patient's vocal behaviour and then a straw “breaks the camels back”.
    o Occasionally after a surgery, the intubation or the surgery may injury the nerve to the vocal cords and I suspect that many times patients are told, “Just wait, it will get better.” which in some sense is the truth. The voice improves, but then... the problem hovers along in a subclinical fashion, appearing at some later time as a seemingly mysterious vocal weakness.
    o And because the vocal cord may be moving normally (in terms of abduction and adduction) or nearly normally, the patient will even give the history that they have seen an ENT doctor (otolaryngologist) and were told that the vocal cords were functioning normally.
    Character of a patient with Unilateral Recurrent Laryngeal Nerve Injury


    • weak voice
    • high pitched voice
    • air wasting voice
    • frustrated
    • Talkativeness scale: whole range
    o at times the patient will rate their current ability to talk rather than their innate degree of talkativeness and give a low rating
    Vocal capabilities
    • Speaking voice
    o air wasting
    • Yelling voice
    o soft edged shout
    o luffing sound (asynchronous vibration like a sail flapping in the wind) on loud phonation at low pitch
    • Maximum phonation time
    o markedly reduced at anchor pitch (often less than 10 seconds)
    • Pitch range
    o obligate falsetto (physical inability to phonate in other than falsetto register) This is the opposite of a superior laryngeal nerve injury where the TA and LCA provide tension at low pitch but the cricothyroid is unable to provide additional tension to raise the pitch
    o diplophonia - less noticeable at higher pitch as cricothyroids begin to tense the atrophic vocal fold.
    • Vegetative sounds - cough
    o nonpercussive cough
    Laryngeal Exam

    • rigid laryngoscope
    o may be in paramedian or lateralized position
    o complete immobility
    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 that is taking place
    o bowing
    • flexible laryngoscope
    o same motion findings should be present
    o Unilateral atrophy or noodle like vocal fold
    o Capacious ventricle on the affected side
    o Conus may also show some tissue loss
    o abnormal configuration of posterior glottis even if vocal processes oppose each other
    Treatment

    Medical• none


    Behavioral
    Voice building exercises
    • In its simplest form, this could amount to 10 minutes three times a day reading aloud as if projecting the voice to an audience.
    • With this amount of dedication, there should be some improvement within three weeks
    • This would be most useful if there is evidence of reinnervation or incomplete paralysis where the thyroarytenoid muscle is not atrophied.
    Surgical

    • Medialization laryngoplasty
    o Medialization laryngoplasty with implant material (also known as a Type I or Isshiki thyroplasty)
     Gore-tex thyroplasty products (look halfway down their page).
     Carved silicon or silastic block
     Preformed implants
     VoCoM by Smith & Nephew. They include an instruction page
     Montgomery Thyroplasty implant system
     cartilage - may reabsorb with time
     Patient information on implants
    o Medialization with an in office injection
     Collagen
     Bovine collagen Zyplast by Mcghan Pharmaceuticals
     Human collagen Cymetra by LifeCell Corporation
     Coapt voice gel
     Patient information on injections
     Gelfoam - indicated for about 1 months of relief when the possibility of spontaneous neurologic recovery exists but off market because of a recall on the product 4/2001.
     Teflon
     permanent
     has long term risk of granuloma formation

    • Reinnervation
    o This procedure typically supplies bulk but not mobility to the intrinsic larynx of the larynx
    o It effectively provides the same benefit as a medialization procedure.
    o It takes 6 to 12 months to have an effect.
    o It does avoid the use of an implant.
    o Some other nerve may have to be used and sacrificed if a stump from the original nerve is unavailable.
     Cranial nerve XII - Would you give up the use of a portion of your tongue (which is used for articulation) to have a stonger voice when an artifical implant would do the same thing?
     Ansa cervicalis - I have not heard of any significant morbidity to sacrificing this nerve
    .
    Last edited by trimurtulu; 01-07-2009 at 07:12 PM.

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