title: Superior laryngeal nerve injury: effects, clinical findings, prognosis, and management options.
abstract: OBJECTIVE
  The superior laryngeal nerve (SLN) provides motor innervation to the cricothyroid muscle. However, the functions of this muscle and the anatomic variations of the nerve that supplies it are not fully understood. SLN paresis and paralysis (SLNp) is difficult to diagnose because of a lack of consistent laryngeal findings, and its effects on the voice likely go beyond simple pitch elevation control.
  
  
  RESULTS
  Although SLNp has traditionally been thought to lead to voice pitch limitation, recent research findings reveal multiple roles for this nerve in voice and speech. Cricothyroid muscles are the primary controls of fundamental frequency of voice. SLNp can lead to significant contraction of pitch range, vocal fold vibratory phase asymmetry, and acoustic aperiodicity, thus leading to an overall poor vocal quality. In addition, cricothyroid muscles may also play a role in pitch lowering and shifting from voiced to unvoiced sounds during speech.
  
  
  CONCLUSIONS
  Subtle signs, symptoms, and diagnostic findings associated with SLNp make this disorder difficult to characterize clinically. Lack of treatment methodologies to restore the dynamic action of the cricothyroid muscles poses difficulties in treating patients with this condition. A more thorough understanding of the effects of SLNp will improve diagnosis and treatment.
authors.affiliation: Laryngeal Physiology Laboratory, Department of Head and Neck Surgery, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Michael I
authors.initials: MI
authors.lastname: Orestes
authors.forename: Dinesh K
authors.initials: DK
authors.lastname: Chhetri
mesh_terms: D006801:Humans; D061224:Laryngeal Nerve Injuries / Q000175:diagnosis* / Q000503:physiopathology / Q000628:therapy*; D007823:Laryngeal Nerves; D011379:Prognosis