Craniofacial Muscles

11 Laryngeal Muscle Response to Neuromuscular Diseases and Speci fi c Pathologies
195
procedure to re-establish adequate airway patency, often through a tracheostomy.
Surgical manipulation of one arytenoid cartilage also will create a suf fi cient airway
by either removing the arytenoid entirely or suturing it laterally (Gardner and
Benninger 2006 ; Lawson et al. 1996 ; Feehery et al. 2003 ) . If an arytenoid lateralization
is performed, voice quality will be permanently weakened and aphonic. If
bilateral paralysis of the folds results in a paramedian or laterally abducted position,
ventilation is no longer a concern but airway protection becomes a much
larger threat because of the inability of the vocal folds to adequately close to prevent
aspiration. With bilateral adductor paralysis in the paramedian con fi guration,
neither voice production nor airway protection can be achieved, with patients
often requiring gastrostomy tube feedings because of poor airway protection.
Augmentative communication aids such as speech ampli fi ers and electrolarynx
devices have been used before to augment the “whispered” voice. In some cases,
vocal fold contracture and fi brosis may arise several months after injury. These
conditions result in a drawing of the folds closer to midline, allowing for harsh
and breathy phonation quality to emerge and improvements to airway management
during swallowing (Stemple et al. 2009 ) .
11.9 Superior Laryngeal Nerve Paralysis: Unilateral
or Bilateral
The external branch of the SLN innervates the CT while internal branches provide
for sensation to the inner lumen of the larynx. Unlike RLN trauma, SLN injury is
not readily observable and dif fi cult to ascertain, especially in unilateral cases
(Dursum et al. 1996 ; Robinson et al. 2005 ) . In a recent study, Roy et al. ( 2009 )
demonstrated a tilting of the epiglottal petiole toward the side of paralysis during
the production of a high-pitched/eee/sound. In addition, unilateral SLN paralysis
may also result in an oblique positioning or an overlap of the folds because of the
unequal rocking of the cricothyroid joint. The overlap creates a gap between the
folds that limits the midline closure pattern during vocal fold vibration and decreases
the ability to build subglottic air pressure, thus limiting vocal intensity. Often these
voice disturbances are not noticeable during connected speech production, but the
laxness of the affected fold creates an imbalance that reduces the pitch. Most patients
with unilateral SLN paralysis complain of vocal fatigue and the inability to sing
(Dursum et al. 1996 ; Robinson et al. 2005 ) . Bilateral paralysis of the cricothyroid
muscles is rare and must be con fi rmed through the use of LEMG studies (Heman-
Ackah and Barr 2006 ; Sataloff et al. 2004 ) . If paralysis should occur, the vocal folds
will lack their normal tone and will not lengthen suf fi ciently during attempts to
increase pitch. Voice quality is limited in frequency, intensity range, and stability.
Although there is no medical treatment for SLN paralysis, behavioral voice therapy
may help maximize vocal potential.