Laryngeal Hemiplegia: What the Research Says

Evidence from 40 peer-reviewed studies

3 RCT

1 Cohort Study

19 Case Report

17 Expert Opinion

What Professionals Should Know

•Modified laryngoplasty with cricoarytenoid joint ankylosis provides superior long-term maintenance of arytenoid abduction compared to standard laryngoplasty, reducing the need for revision surgery in horses with laryngeal hemiplegia
•The procedure achieves mechanical stability through joint fusion rather than relying on suture tension alone, offering more durable results for performance horses
•Consider this modified approach for horses requiring laryngoplasty, particularly those with high performance demands where loss of abduction would be career-limiting
•For sport horses working at typical intensities (sub-maximal), both LPVC and MPA are functionally equivalent—procedure choice can be based on surgeon preference, cost, or horse anatomy rather than expected outcome differences.
•Understand that neither procedure fully restores normal airway function at peak exertion; horses may have residual performance limitations at maximal effort despite successful surgery.
•Both procedures increase aspiration risk by compromising laryngeal protection during exercise, so monitor for respiratory signs post-operatively and manage exercise resumption carefully.
•Do not use laser vocal cordectomy as a treatment for roaring in laryngeal hemiplegia cases, as it fails to reduce respiratory noise despite some pressure reduction
•Bilateral ventriculocordectomy remains a more effective surgical option if noise reduction is the clinical goal in affected horses
•Understand that reducing upper airway pressure alone does not translate to clinically meaningful noise reduction in this condition
•If a horse continues to make respiratory noise after laryngoplasty, perform exercising video-endoscopy to identify concurrent airway problems rather than assuming surgery failure
•Ensure ventriculectomy is performed concurrently with laryngoplasty to reduce postoperative respiratory noise complications
•Owner satisfaction with laryngoplasty does not correlate with objective airway function; objective examination is essential for detecting ongoing pathology
•When selecting suture material for prosthetic laryngoplasty, expect polyester to elongate more overall but show less knot slippage than UHMWPE alternatives—trade-offs exist between construct stability and knot security
•Consider applying cyanoacrylate to polyester knots as a simple intraoperative step to reduce knot elongation by ~1 mm and help preserve long-term arytenoid abduction
•UHMWPE tape appears most resistant to total construct elongation and may better maintain surgical correction over time, though knot stability requires further investigation
•Preserve the C1 nerve during prosthetic laryngoplasty procedures to maintain thyrohyoideus function and avoid iatrogenic denervation
•Consider C1 nerve anatomy and variable branching patterns when planning cervical nerve grafts for laryngeal hemiplegia treatment
•Recognition of C1 innervation of TH muscle may inform development of new surgical approaches for dorsal displacement of the soft palate management
•If a horse develops persistent coughing or swallowing difficulties after laryngoplasty, prosthesis removal is a viable treatment option with good success rates (66-75%)
•Arytenoid abduction grade does not predict which horses will respond positively to prosthesis removal, so clinical response rather than endoscopic findings should guide management decisions
•Expect about 1 in 30 laryngoplasty cases to require prosthesis removal, so counsel clients appropriately about potential post-operative complications
•Standing laryngeal surgery is now feasible using cervical plexus blocks, eliminating general anesthesia risks in horses with poor prognosis for recovery
•This technique provides an alternative for horses where recumbency poses safety concerns or where rapid return to function is critical
•Practitioners should consider referral for standing prosthetic laryngoplasty in suitable candidates to improve surgical outcomes and reduce perioperative complications
•Tracheal resection and anastomosis is a viable surgical option for managing traumatic tracheal stenosis, even when complications occur
•Post-operative mucosal web formation may occur and can be managed with transendoscopic laser surgery if it causes clinical signs
•Careful surgical technique and nerve identification are critical during tracheal anastomosis to minimize recurrent laryngeal nerve damage; if damage occurs, laryngoplasty can still achieve functional recovery
•Monitor horses post-laryngoplasty for signs of DDSP including respiratory noise and poor performance, as this complication can occur despite successful laryngeal surgery
•Be aware that palatal dysfunction following laryngoplasty may require additional diagnostic investigation and potentially further intervention to resolve performance issues
•Include DDSP in the differential diagnosis for horses with persistent respiratory noise or poor performance following laryngoplasty
•Week 6 postoperative endoscopic assessment is more predictive of long-term laryngoplasty outcome than week 1 assessment; use week 6 findings for prognostication rather than early postoperative grades
•Resting arytenoid abduction grade does not reliably predict stability during exercise, so horses with adequate resting abduction may still develop dynamic collapse during work
•Approximately 1 in 5 laryngoplasty cases will show cartilage instability during exercise despite adequate resting abduction; consider this when setting post-operative expectations with owners
•Adding ventriculocordectomy to laryngoplasty may improve rima glottidis opening and reduce suture-related complications by requiring less tension on the prosthetic suture
•This combined surgical approach could potentially improve airway caliber in horses with laryngeal hemiplegia, though clinical outcomes require in vivo confirmation
•The mechanical advantage gained may be particularly beneficial in cases where maximum airway opening is desired or where suture-related complications (nerve damage, dehiscence) are a concern
•Perform pre-operative radiographic examination of the larynx before prosthetic laryngoplasty to identify areas of increased radiodensity that may indicate cartilage induration and complicate needle passage
•Be prepared for difficult needle penetration through the cricoid cartilage in older horses; consider using surgical techniques that minimize or avoid direct needle passage through hardened cartilage
•Understand that radiographic findings of increased density may reflect proteoglycan loss and cartilage stiffening rather than true mineralization, affecting surgical planning
•If a horse has no visible arytenoid abduction at rest after laryngoplasty, expect dynamic collapse during exercise; however, grade 3-4 resting abduction does not guarantee normal upper airway function during work.
•Exercise endoscopy is necessary to fully assess post-laryngoplasty patients with ongoing poor performance, as resting exams miss critical dynamic obstructions involving multiple structures.
•Respiratory noise alone cannot diagnose the cause of upper airway dysfunction—look for concurrent vocal fold billowing, soft palate displacement, and pharyngeal involvement to explain poor performance.
•Laryngoplasty sutures are subject to dynamic stress during normal swallowing and coughing; suture selection and surgical technique must account for these high-load functional demands.
•Understanding the biomechanical forces on laryngoplasty implants can inform decisions about suture material strength and attachment methods to improve long-term durability.
•Recurrent laryngeal nerve involvement significantly affects the forces transmitted to laryngoplasty hardware, which may have implications for surgical planning and post-operative management.
•Branchial remnant cysts should be considered in the differential diagnosis for mature horses presenting with throat latch masses, dysphagia, or retropharyngeal swelling—not just in foals as previously reported
•Ultrasonography is a useful diagnostic tool showing characteristic thick-walled cysts with fluid and clots; definitive diagnosis requires squamous epithelium identification via cytology or histopathology
•Surgeons should counsel owners that right laryngeal hemiplegia is a frequent complication of BRC excision due to proximity to the recurrent laryngeal nerve, with potential impacts on athletic performance
•Surgeons should not be discouraged by moderate (grade 3) long-term laryngeal abduction after laryngoplasty, as it does not predict poor racing performance in National Hunt horses
•Horses with excellent immediate postoperative abduction (grade 1) paradoxically lose more abduction over time; moderate initial abduction (grade 3) appears more stable
•Abduction grade alone should not be used as a prognostic indicator for postoperative racing success in racehorses
•This minimally invasive approach offers an alternative to traditional general anaesthesia surgical techniques, potentially reducing perioperative risks and recovery time
•Standing sedated procedure may improve client convenience and reduce costs associated with general anaesthesia and hospitalization
•Technique targets both noise reduction and functional airway improvement in horses with laryngeal hemiplegia
•About 6-8 in 10 racehorses will return to racing after partial arytenoidectomy without closure, but expect lower performance levels overall
•Previously raced horses have slightly better return-to-racing rates than those racing for the first time postoperatively
•This technique saves surgical time and may avoid mucosal closure complications, making it a practical middle-ground option when addressing laryngeal hemiplegia or arytenoid chondropathy
•Laryngoplasty effectively reduces respiratory noise in horses with laryngeal hemiplegia, providing objective evidence to support surgical intervention
•Quantitative noise measurements can now be used to assess surgical success and guide treatment decisions
•This procedure should remain the standard treatment approach for laryngeal hemiplegia when noise reduction or airway improvement is the clinical goal
•For show and performance horses presenting with laryngeal hemiplegia, ventriculocordectomy can significantly reduce respiratory noise, which is often the primary client complaint
•Surgical intervention should be considered when noise is the limiting factor rather than performance capacity
•This procedure provides a quantifiable surgical option where previously only subjective assessments were available
•Thyroidectomy can effectively resolve clinical signs of tracheal compression from thyroid masses, but recurrent laryngeal nerve injury is a significant risk—obtain pre- and post-operative laryngoscopic examinations to document this complication
•Careful surgical dissection and isolation of the recurrent laryngeal nerve is essential to minimize laryngeal hemiplegia risk; consider this outcome when discussing surgery with owners
•Use ultrasound to localize and measure thyroid masses for surgical planning, but do not rely on imaging to determine tumor type—histopathology will be needed post-operatively
•Cordopexy alone is insufficient for treating laryngeal hemiplegia and should not be used as a standalone procedure; combining it with laryngoplasty provides the benefit of dual stabilization
•Combined cordopexy with modified laryngoplasty is biomechanically equivalent to standard laryngoplasty in restoring airway patency, offering surgeons an alternative technique with potentially different surgical applications
•These in vitro results suggest vocal cord fixation paired with arytenoid abduction provides superior airway mechanics; clinical validation is needed before widespread adoption in practice
•Suture anchor implants may be advantageous if minimizing initial abduction force is clinically desirable, though long-term stability data is needed
•Tie-bolt implants offer superior mechanical durability and resistance to cyclic loading degradation, potentially providing longer-lasting surgical outcomes
•Choice between implant types should consider both surgical ease (suture anchor advantage) and long-term mechanical stability (tie-bolt advantage) based on individual case requirements
•The titanium corkscrew anchoring technique offers biomechanical advantages over traditional Jamshidi needle methods, requiring less force and causing less tissue disruption during laryngoplasty
•Corkscrew implantation may enable more physiologic muscle function by minimizing CAD muscle indentation and laryngeal rotation, potentially improving long-term surgical outcomes
•This technique opens possibilities for combined nerve graft procedures in recurrent laryngeal neuropathy cases, which could improve functional recovery beyond current single-procedure approaches
•CFD modeling offers a non-invasive tool to predict and compare outcomes of different RLN surgical procedures before clinical application
•This computational approach may help surgeons optimize technique selection and refinement for individual cases of laryngeal hemiplegia
•Future development of CFD analysis could reduce trial-and-error in surgical planning for obstructive airway disorders
•Polyblend tape suture with a cannula at the muscular process provides superior biomechanical stability during cyclic loading, suggesting better long-term holding strength in clinical use
•Standard polyester sutures (Ethibond) show greater tissue migration and creep, which may compromise surgical outcomes; consider upgrading to polyblend tape constructs for laryngoplasty procedures
•The cannula reinforcement technique is worth adopting regardless of suture type, as it reduces construct failure risk—this is a simple modification that improves performance
•Laryngeal specimens preserved through multiple freeze-thaw cycles retain adequate cartilage integrity for experimental testing of laryngoplasty techniques, allowing for better utilization of cadaveric research material
•Surgeons can be confident that repeated freezing and thawing of laryngeal tissues does not compromise the biomechanical properties relevant to laryngoplasty surgical outcomes
•A dynamic laryngoplasty system shows promise for improving airway patency in laryngeal hemiplegia by reducing resistance during airflow, potentially offering better performance than static suture procedures alone
•The system appears to reach optimal efficacy at moderate pressure levels (25 psi), suggesting clinical protocols should target this range rather than maximum pressurization
•These in vitro findings warrant progression to in vivo and clinical trials to determine real-world applicability and whether dynamic systems outperform conventional static laryngoplasty techniques
•Understanding the precise anatomical boundaries of the vestibulum esophagi is critical for surgeons performing laryngoplasty—awareness alone reduced complication rates from 72% to 9%
•When placing sutures through the arytenoid muscular process during laryngoplasty, stay rostral and avoid deep penetration to prevent entering the esophageal lumen or adventitia
•This anatomical knowledge should be emphasised in surgical training and case planning before performing prosthetic laryngoplasty procedures
•A dynamic system could potentially provide additional arytenoid abduction beyond what fixed laryngoplasty alone achieves, though clinical benefit remains to be proven
•This is early-stage technology development; results are from dissected larynges and do not yet demonstrate effects on actual airway function or patient outcomes
•Further research is needed to determine if this system would reduce post-operative stridor or improve exercise tolerance compared to conventional laryngoplasty
•FASTak II anchors may improve surgical outcomes in laryngoplasty by requiring less suture tension to achieve adequate arytenoid abduction, potentially reducing postoperative loss of function
•Consider FASTak II technique as preferred attachment method over traditional suture patterns for horses undergoing laryngoplasty
•Lower load requirements with FASTak II may translate to improved long-term durability of the surgical repair
•Metallic button reinforcement of cricoid sutures may reduce loss of arytenoid abduction and improve long-term stability of laryngoplasty, potentially reducing recurrence of clinical signs.
•Standard single-pass suture techniques show greater suture migration under cyclic loading; consider reinforcement strategies in cases at high risk of recurrence.
•These ex vivo findings suggest metallic button constructs warrant in vivo clinical trials, but until then, standard techniques remain the clinical reference.
•Laryngoplasty repairs lose significant abduction under physiologic-level forces simulating early postoperative swallowing and coughing—postoperative management restricting these activities may be critical
•Using a clamp to pre-abduct the arytenoid before knot tying does not improve long-term maintenance of abduction, so this surgical refinement may not be worth the additional operative time
•Consider modified postoperative protocols or alternative surgical techniques if mechanical failure occurs in nearly 7% of cases within the first few hundred cycles
•The ALPS system may offer improved durability and reduced motion at the surgical site compared to traditional single-suture laryngoplasty, potentially reducing recurrence of clinical signs
•Reduced distraction with ALPS could translate to better long-term arytenoid positioning and functional outcomes in RLN cases
•In vitro findings are promising but clinical trials are needed to confirm whether improved mechanical properties translate to better surgical success rates in living horses
•Use Ethibond suture material for laryngoplasty procedures as it provides superior mechanical strength and durability in laboratory testing, potentially reducing risk of abduction loss
•Be aware that arytenoid attachment points are mechanistically weaker than cricoid attachment with certain suture materials, which may influence surgical technique selection
•While this is cadaveric work, Ethibond's lower displacement under cyclic loading suggests better long-term stability and reduced risk of progressive loss of arytenoid abduction post-operatively
•PMMA augmentation of laryngoplasty may reduce early post-operative abduction loss by mechanically stabilizing the cricoarytenoid joint against physiological airflow forces
•This technique could improve long-term outcomes in horses undergoing laryngoplasty for recurrent laryngeal neuropathy by reducing suture strain
•Further in vivo studies are needed before clinical adoption, but the biomechanical evidence supports investigation as an adjunctive surgical technique
•When performing laryngoplasty for laryngeal hemiplegia, aim for maximal arytenoid abduction rather than partial abduction to prevent airway collapse during high-intensity exercise
•Partial abduction (88% of maximal area) may represent an acceptable surgical compromise, but anything less risks compromising airway patency in working racehorses
•Even modest reductions in arytenoid abduction force the horse's respiratory system to work harder during exercise, reducing efficiency and performance
•IOS offers significantly improved sensitivity over conventional testing for diagnosing partial upper airway obstructions in resting horses, enabling earlier intervention
•The ability to differentiate upper versus lower airway disease patterns with IOS could refine treatment protocols and prognosis discussions with clients
•IOS provides objective, quantifiable assessment of bronchodilator response and identifies persistent dysfunction post-treatment, supporting treatment efficacy evaluation and clinical decision-making
•Laryngoplasty with ventriculectomy/ventriculocordectomy is an effective treatment for laryngeal hemiplegia in draft horses, with ~90% improving performance and 72% eliminating respiratory noise entirely
•Anesthetic complications in draft horses are higher than in light horses (11% total), so informed consent and careful anesthetic management are essential
•Maximizing postoperative abduction angle (≥70% of maximum) appears important for achieving normal performance without respiratory noise

Key Research Findings

Modified laryngoplasty resulted in fibrous ankylosis of the cricoarytenoid joint, confirmed histologically in all treated horses

Parente Eric J, 2011

Loss of arytenoid abduction at 3 months was significantly greater in control laryngoplasty (n=3) versus modified procedure (n=5)

Parente Eric J, 2011

Translaryngeal impedance was significantly lower in the modified laryngoplasty group compared to control, indicating better airway patency

Parente Eric J, 2011

Intact sutures maintained lower impedance compared to cut sutures, demonstrating the stabilizing effect of the surgical modification

Parente Eric J, 2011

Both laryngoplasty/vocal cordectomy (LPVC) and modified partial arytenoidectomy (MPA) restored airway mechanics and blood gases to near-normal at 80% maximal heart rate, with only minor differences between procedures.

Radcliffe Catherine H, 2006

At 100% maximal heart rate, both procedures improved all variables but failed to fully restore minute ventilation, arterial pH, and PaCO₂ compared to control.

Radcliffe Catherine H, 2006

Both LPVC and MPA resulted in equivalent tracheal contamination post-exercise, indicating similar compromise of laryngeal protective mechanisms.

Radcliffe Catherine H, 2006

Sub-maximal exercise ventilation is normalized by either procedure, but maximal exercise performance remains compromised with slight superiority of LPVC over MPA.

Radcliffe Catherine H, 2006

Laser vocal cordectomy failed to reduce sound level or formant 1 and 3 intensity in horses with laryngeal hemiplegia during maximal exercise

Brown Jennifer A, 2005

The procedure reduced upper airway pressure and formant 2 intensity but these remained significantly elevated compared to baseline

Brown Jennifer A, 2005

Unilateral laser cordectomy provided equivalent obstruction relief to bilateral ventriculocordectomy but without noise reduction benefits

Brown Jennifer A, 2005

78% of horses showed some form of upper airway collapse at exercise despite 93% of owners reporting surgery as beneficial

Barnett T P, 2013

Horses with poor arytenoid abduction (grades 4-5/5) were 6 times more likely to make respiratory noise than those with good abduction (grades 2-3/5)

Barnett T P, 2013

Horses without concurrent ventriculectomy were 4.9 times more likely to produce respiratory noise postoperatively

Barnett T P, 2013

Palatal dysfunction prevalence increased from 24% at rest to 56% at exercise, with significant association between resting and exercising diagnosis

Barnett T P, 2013

Evidence Base

A modified laryngoplasty approach promoting ankylosis of the cricoarytenoid joint.

Parente Eric J, Birks Eric K, Habecker Perry (2011) — Veterinary surgery : VS

RCT

A comparison of laryngoplasty and modified partial arytenoidectomy as treatments for laryngeal hemiplegia in exercising horses.

Radcliffe Catherine H, Woodie J Brett, Hackett Richard P et al. (2006) — Veterinary surgery : VS

RCT

Laser vocal cordectomy fails to effectively reduce respiratory noise in horses with laryngeal hemiplegia.

Brown Jennifer A, Derksen Frederik J, Stick John A et al. (2005) — Veterinary surgery : VS

RCT

Long-term exercising video-endoscopic examination of the upper airway following laryngoplasty surgery: a prospective cross-sectional study of 41 horses.

Barnett T P, O'Leary J M, Parkin T D H et al. (2013) — Equine veterinary journal

Cohort Study

The effect of cyanoacrylate on knot elongation in three sutures used for prosthetic laryngoplasty in the horse.

Watkins Amanda R, Ford Matt, van Eps Andrew W et al. (2023) — Veterinary surgery : VS

Laryngeal Hemiplegia: What the Research Says

What Professionals Should Know

Key Research Findings

Evidence Base

A modified laryngoplasty approach promoting ankylosis of the cricoarytenoid joint.

A comparison of laryngoplasty and modified partial arytenoidectomy as treatments for laryngeal hemiplegia in exercising horses.

Laser vocal cordectomy fails to effectively reduce respiratory noise in horses with laryngeal hemiplegia.

Long-term exercising video-endoscopic examination of the upper airway following laryngoplasty surgery: a prospective cross-sectional study of 41 horses.

The effect of cyanoacrylate on knot elongation in three sutures used for prosthetic laryngoplasty in the horse.

Thyrohyoideus muscle innervation in the horse.

Outcomes of horses treated with removal of a laryngoplasty prosthesis.

Unilateral cervical plexus block for prosthetic laryngoplasty in the standing horse.

Tracheal resection and anastomosis after traumatic tracheal stenosis in a horse.

Characterisation of palatal dysfunction after laryngoplasty.

Long-term maintenance of arytenoid cartilage abduction and stability during exercise after laryngoplasty in 33 horses.

In vitro effect of ventriculocordectomy before laryngoplasty on abduction of the equine arytenoid cartilage.

Induration of the cricoid cartilage complicates prosthetic laryngoplasty in a horse.

Exercising videoendoscopic evaluation of 45 horses with respiratory noise and/or poor performance after laryngoplasty.

Equine laryngoplasty sutures undergo increased loading during coughing and swallowing.

Branchial remnant cysts of mature and juvenile horses.

Postoperative race performance is not correlated with degree of surgical abduction after laryngoplasty in National Hunt Thoroughbred racehorses.

Effects of unilateral laser-assisted ventriculocordectomy in horses with laryngeal hemiplegia.

Performance after partial arytenoidectomy without mucosal closure in 27 Thoroughbred racehorses.

Effect of laryngoplasty on respiratory noise reduction in horses with laryngeal hemiplegia.

Ventriculocordectomy reduces respiratory noise in horses with laryngeal hemiplegia.

Unilateral thyroidectomy in 6 horses.

An in vitro comparison of cordopexy, cordopexy and laryngoplasty, and laryngoplasty for treatment of equine laryngeal hemiplegia.

Biomechanical testing of three constructs for prosthetic laryngoplasty in horses demonstrates advantages of differing metallic implants in the arytenoid cartilage.

Equine laryngoplasty: Effects of three anchoring techniques in the muscular process and three positions for suture implantation in the cricoid cartilage.

Comparison of treatments for equine laryngeal hemiplegia using computational fluid dynamic analysis in an equine head model.

Ex vivo biomechanical evaluation of polyester and polyblend suture techniques to perform equine laryngoplasty.

The effect of repeated freezing and thawing on the suture pull-out strength in equine arytenoid and cricoid cartilages.

Evaluation of a prototype dynamic laryngoplasty system in vitro with an equine vacuum airflow system.

Anatomy of the vestibulum esophagi and surgical implications during prosthetic laryngoplasty in horses.

In vitro evaluation of the effect of a prototype dynamic laryngoplasty system on arytenoid abduction.

In vitro comparison of 3 techniques of prosthesis attachment to the muscular process of the equine arytenoid cartilage.

Ex vivo biomechanical stability of 5 cricoid-suture constructs for equine laryngoplasty.

An ex vivo model to evaluate the effect of cyclical adductory forces on maintenance of arytenoid abduction after prosthetic laryngoplasty performed with and without mechanical arytenoid abduction.

In vitro mechanical testing of an alternate laryngoplasty system (ALPS) for horses.

Mechanical evaluation of the equine laryngoplasty.

Intra-articular stabilisation of the equine cricoarytenoid joint.

Implications of different degrees of arytenoid cartilage abduction on equine upper airway characteristics.

Qualitative and quantitative evaluation of equine respiratory mechanics by impulse oscillometry.

Laryngoplasty with ventriculectomy or ventriculocordectomy in 104 draft horses (1992-2000).