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Oral palatopharyngoplasty
Abstract
This study was an attempt to assess the validity of Oral-Palatopharyngo-plastic surgery 1 as a means of treating horses which presented with Acquired Pharyngeal Dysfunction (APD)2.Both clinical, and to some degree performance parameters, were investigated on a pre and post operative basis. A comparison of raced versus unraced horses presented for surgery, was also undertaken.The results, using the assessment facilities available to the author, seemed to indicate a useful prognosis from both a clinical and performance viewpoint.
... The Oral Palatopharyngoplasty (OPP) or Ahern Procedure first published in 1992 [1] like many other surgical procedures continued to evolve with continued modification to deal with inherent issues such as inadequate tension resulting in lesser rates of clinical improvement and conversely over tensing with resultant suture dehiscence and poor outcomes. ...
... If only mild tension increases were evident then TRI's were not utilised. An OPP procedure also involved stripping of mobile subepiglottic mucosa as previously described [1]. This mucosa could be palpated and elevated manually and resected via a laryngotomy with the horse in lateral recumbency. ...
... This was at odds with the author's experiences. He had previously stated that the prognosis would seem to be poor with second intention healing [1]. ...
An oral palatopharyngoplasty, was a surgical procedure developed in the 1980’s and first published in 1992. The purpose of the procedure was to reduce the incidence of palatal instability (PI) and subsequent dorsal displacement of the soft palate (DDSP). In the years following the first publication, the procedure underwent numerous modifications to improve the likelihood of obtaining useful increases in tension in the tissues supporting the palatine aponeurosis and at the same time reducing the incidence of wound breakdown. These changes have led to the present technique now referred to as a Modified Oral Palatopharyngoplasty or Modified Ahern Procedure.
... The upper airways procedure referred to as an oral palatopharyngoplasty (OPP) [1] had been used since the late 1980's to treat horses that presented with disruption of the oropharyngeal seal (OPS) [2,3]. This disruption was more recently referred to as palatal instability (PI) [3][4][5], which in some cases progressed to dorsal displacement of the soft palate (DDSP) [4,6]. ...
... The decision to perform an oral palatopharyngoplasty [1] was taken. The aim of the surgery was to reduce the incidence of PI and potentially any altered behaviours that may have been associated with this condition. ...
... The aim of the surgery was to reduce the incidence of PI and potentially any altered behaviours that may have been associated with this condition. Post operatively the horse was rested for 8 weeks [1]. ...
... In the absence of any other etiological avenues, the possibility that PI [9] or pharyngeal instability [12] with resultant UAO may have been impacting negatively on the horse's ability to experience sufficient paradoxical sleep was discussed with the owner. It was then agreed that the horse would undergo an oral palatopharyngoplasty (OPP) [13] procedure in an attempt to reduce the incidence of this instability. Following surgery the horse was rested for eight weeks prior to resuming training. ...
... In the absence of environmental or social changes [4] that could precipitate sleep deprivation and thence sleep attacks, and given the extensive history, it was decided that an upper airways examination was appropriate. Palatal instability (PI) were diagnosed and an oral palatopharyngoplasty (OPP) [13] was performed. Initial weight loss coincided with a rationed fibre only diet in the two weeks following surgery. ...
A six year old thoroughbred gelding presented with a two year history of somnolence and altered behavior of two years duration. In the three months immediately preceding presentation episodes of sleep attacks and accompanying sleep terrors were observed. There had been no evidence of recumbent or paradoxical sleep during this period. An examination of the upper airways revealed evidence of palatal instability (PI). An oral palatopharyngoplasty (OPP) was performed to reduce this instability (PI). Clinical observations in the eight months following surgery suggested a possible link between PI, upper airways obstruction (UAO) and a horse’s ability to achieve adequate paradoxical sleep.
... strap muscle resection) aimed at preventing caudal retraction of the larynx, intrinsic procedures (e.g. staphylectomy, epiglottic augmentation, rostral palatoplasty, thermal or surgical, and caudal palatoplasty) aimed at stiffening the palate and/or the epiglottic cartilage, or combinations of these intrinsic and extrinsic procedures (Quinlan et al. 1949; Cook 1981; Peloso et al. 1992; Ahern 1993; Carter et al. 1993; Anderson et al. 1995; Llewellyn and Petrowitz 1997; Tulleners et al. 1997; Ordidge 2001; Hogan et al. 2002; Parente et al. 2002). Intrinsic approaches, such as rostral palatoplasty (Ahern 1993), thermal palatoplasty (Ordidge 2001), and staphylectomy (Anderson et al. 1995) have reported success rates of 75, 66.5 and 60%, respectively. ...
... staphylectomy, epiglottic augmentation, rostral palatoplasty, thermal or surgical, and caudal palatoplasty) aimed at stiffening the palate and/or the epiglottic cartilage, or combinations of these intrinsic and extrinsic procedures (Quinlan et al. 1949; Cook 1981; Peloso et al. 1992; Ahern 1993; Carter et al. 1993; Anderson et al. 1995; Llewellyn and Petrowitz 1997; Tulleners et al. 1997; Ordidge 2001; Hogan et al. 2002; Parente et al. 2002). Intrinsic approaches, such as rostral palatoplasty (Ahern 1993), thermal palatoplasty (Ordidge 2001), and staphylectomy (Anderson et al. 1995) have reported success rates of 75, 66.5 and 60%, respectively. Strap muscle resection techniques reported are associated with success rates ranging from 58 to 73% (Harrison and Raker 1988; Anderson et al. 1995; Duncan 1997; Llewellyn and Petrowitz 1997; Parente et al. 2002). ...
Correct placement of sutures ('laryngeal tie-forward') in experimentally created dorsal displacement of the soft palate (DDSP) has been observed to replace the function of the thyrohyoideus muscles and prevent DDSP.
The 'laryngeal tie-forward' procedure would prevent or delay the occurrence of DDSP during exercise in horses with naturally occurring DDSP and therefore improve performance.
A clinical population (n = 116), mainly of racehorses was presented for treatment of naturally occurring exercise-induced DDSP. All horses underwent the 'laryngeal tie-forward' procedure. The relative position of the thyroid and cricoid cartilage in relation to the caudal aspect of the basihyoid bone was recorded; follow-up was obtained by telephone communication with trainers, owners and/or referring veterinarians. In addition, a performance index and earnings were determined using race records.
Preoperatively, the median distance between the caudal aspect of the basihyoid bone and rostral aspect of the thyroid cartilage was 3.5 cm. Post operatively, the thyroid cartilage was moved a median distance of 4 cm rostrally and the larynx was shown to be in a position more rostral and dorsal than in preoperative radiographs. Of 98 horses for which follow-up was available, the performance of 87% was classified as improved, 12% as unchanged and 2% as worse. In 20 horses in which the diagnosis had been confirmed by treadmill videoendoscopy, 80% had a significantly increased performance index and earnings (P = 0.007). For the entire population, there was a significant improvement in performance index and earnings after surgery (82%) (P = 0.0001).
Placing the larynx in a more rostral and dorsal position may have improved the performance in 80-82% of the horses affected with naturally-occurring DDSP.
'Laryngeal tie-forward' is a surgical technique that has a measurable effect on the position of the larynx and offers an alternative therapy for treating horses affected with DDSP. More experience may be needed with this technique prior to its widespread use in horses with a clinical diagnosis of DDSP.
... Subepiglottic resection performed in conjunction with any tension palatoplasty procedure was classified as variation in technique. This was described as part of the original technique (Ahern 1993a) but has subsequently been omitted by some surgeons. Furthermore, where studies combined the results from horses undergoing tension palatoplasty with and without subepiglottic resection, statistical analysis was performed prior to grouping and showed no significant difference in success rates ). ...
There are numerous treatments for correction of dorsal displacement of the soft palate (DDSP). However, the efficacy of these treatments is controversial and there is little consensus on how best to treat this condition. The aims of this study were to systematically review the literature and to assess the evidence on the clinical effects of interventions for dynamic intermittent DDSP. A secondary objective was to assess whether factors relating to study quality affected reported success rates. Twenty-three studies were included, covering a wide number of interventions but also differing widely is terms of study design, sample size, method of diagnosis, outcome measure and the number lost to follow-up. The assessment of adverse effects was severely limited because of lack of reporting. The way in which success is measured appears to have a great effect on the reported results. Research synthesis has been severely limited because of the heterogeneity in the included studies. The low level of evidence makes it difficult to draw firm conclusions as to the efficacy of procedures for DDSP. Hence it is currently not possible to determine which procedure is the most appropriate. This systematic review highlights the difficulties of studying palatal dysfunction and suggests areas where improvements can be made in future studies.
... Intermittent dorsal displacement of the soft palate (DDSP) results in an expiratory upper-airway obstruction that is often associated with an expiratory sound (Haynes 1983; Hackett et al. 1 9 9 9 ; Holcombe and Ducharme 1999). The cause of DDSP is still larg e l y conjectural, as evidenced by the large variety of surgical treatments ranging from resection of the caudal portion of the soft palate, increasing the stiffness of the epiglottis, resections of a section of various muscles caudal to the basihyoid bone (omohyoid, sternohyoid) and extrinsic laryngeal muscles (sternothyroid), referred to as strap-muscle resection, soft palate-imbrication techniques and combinations of these procedures (Heffron and Baker 1979; Cook 1981; Zertuche et al. 1990; Tulleners and Hamir 1991; Carter et al. 1993; Ahern 1993; Anderson et al. 1 9 9 5 ; Llewellyn 1997). The alleged approximately 60% surgical success rate regardless of the surgical treatment is evidence of our lack of understanding of the aetiology and appropriate treatment (Ducharme and Hackett 1995). ...
Contributes to the understanding of the pathogenesis of dorsal displacement of the soft palate during exercise so that management of this condition could be enhanced.
That the thyrohyoid muscles play an important role in the stability of the laryngo-palatal relationship and that dysfunction of these muscles leads to dorsal displacement of the soft palate (DDSP) during exercise.
Ten horses were exercised on a high-speed treadmill under 4 different treatment conditions: control conditions (n = 10), after resection of thyrohyoid muscles (TH, n = 10), after sham-treatment (n = 5), or after restoration of function of the thyrohyoid muscles with surgical sutures (prosthesis-treatment, n = 6). During trials, the following determinations were made: videoendoscopy of the upper airway, gait frequency and pharyngeal and tracheal static pressures.
None of the 10 horses developed DDSP during 2 separate treadmill-exercise trials under the control conditions. Seven of the 10 horses developed DDSP after resection of the TH muscles, 4 of 5 of these horses still experienced DDSP after sham-treatment, but 5 of 6 horses no longer experienced DDSP at exercise after the prosthesis-treatment. There were significant anomalies in airway pressures, respiratory frequency, and occurrence of DDSP in both the TH resection and sham-treatment conditions compared to control conditions. In contrast, no statistical differences were noted in any of the parameters measured between the prosthesis-treatment and control conditions.
That the function of the TH muscles is important to the stability of the laryngo-palatal relationship and plays a role in the pathophysiology of exercise-induced DDSP.
Management of horses with DDSP could be enhanced by restoring the function of the TH muscles.
Background
Palatal dysfunction is a common cause of poor performance in racehorses. Although conservative management resolves just over 60% of cases, there is a requirement for further intervention in the residual 40% of cases that do not respond. It is proposed that a palatal stiffening technique that is simple to perform, safe, minimally invasive and enables a rapid return to exercise would be an acceptable first intervention. Genipin is a self‐polymerising molecule that bonds to collagen matrices increasing tissue strength, stiffness and resilience. A previous study demonstrated that implanted genipin increased palatal strength and its resistance to deformation and potentially was effective in decreasing likelihood of palatal dysfunction in horses.
Objectives
The objective of the study was to appraise the safety and feasibility of implanting genipin oligomers into the equine soft palate and to report on racehorse trainers' subjective assessment of its usefulness in management of palatal dysfunction.
Study design
Prospective, non‐randomised, pilot study.
Methods
Fifty Thoroughbred racehorses diagnosed with palatal dysfunction were implanted transendoscopically with genipin. The horses were monitored for adverse reactions during hospitalisation. A standard questionnaire provided to the horses' trainers was used to record additional adverse reactions and satisfaction with the animals' subsequent performance. Post‐treatment dynamic endoscopy was performed in a subgroup of animals.
Results
One horse developed adverse clinical signs of pyrexia and reduced appetite, which responded to treatment. Post‐procedural endoscopic examination revealed mild palatal abnormalities in 6 of 50 horses that showed no clinical signs. One horse had mild generalised oedema, four with mild focal swelling and one with a superficial mucosal ulceration at a single site of implantation of the soft palate. Following treatment, 76% of horses were reported to show clinical improvement by their trainers with 24% reported not to show improvement.
Main limitations
The study was not controlled, and outcome measures were mainly subjective.
Conclusions
The procedure was well tolerated, safe, minimally invasive and enabled a rapid return to exercise. Trainer reported improvement was comparable to previously reported palatoplasty procedures.
Tongue‐ties (TTs) are used to aid control and aim to conservatively treat upper airway disorders in racehorses. However, welfare concerns have led to their use being banned in other equestrian disciplines. In the United Kingdom, TTs have been reported to be used in approximately 5% of starts. The frequency of their use elsewhere is unknown. The objectives of this retrospective single cohort study were to estimate the frequency of TT use within the Australian Thoroughbred (TB) racing industry, and to describe usage patterns. Data of all Australian TB horse races from 2010 to 2013 calendar years were collected by accessing the Racing Information Services Australia database. Frequency of TT use was calculated, and usage patterns were explored at the start, horse and trainer levels. Between 2010 and 2013, there were a total of 728,678 starts from 62,377 horses prepared by 4927 trainers and that raced on 1453 race dates across 402 venues. Tongue‐ties were used in 21.4% of starts; however, frequency varied according to location, race, trainer and horse. At the horse level, 32.2% wore a TT at least once and 7.6% wore it at every race on record. At the trainer level, 71.3% used TTs in at least one of their horses but only 1.4% used them systematically. The present study concludes that TT use in Australian TB racehorses, during the period 2010–2013, was common and considerably higher than previously reported in the United Kingdom. Most Australian trainers use the device and appear to adapt its usage according to individual horse and race factors.
This case report describes the endoscopic findings and outcome in 6 horses diagnosed with dynamic epiglottic retroversion (ER) during exercise. Horses included 2 showjumpers, one eventer, one pleasure riding horse and 2 Thoroughbred racehorses. All were adults (age range: 4–10 years). Dorsal angulation of the epiglottis was identified at rest in one horse. However, resting endoscopy was unremarkable in the remaining 5 horses. Exercising endoscopy was performed during high‐speed treadmill exercise in 3 horses and during ridden exercise in the other 3. Intermittent ER occurred during inspiration in all horses and the frequency increased with increasing speed. In 2 horses the epiglottis retroverted beyond the rima glottidis. All horses made an abnormal respiratory noise described as a ‘grunt’ when retroversion of the epiglottis occurred. Poll flexion was found to be an exacerbating factor in the nonracehorses. Two horses continued in work but abnormal inspiratory noise persisted. Surgical treatment, in the form of subepiglottic resection, was attempted in one horse. However, it never raced again after the procedure. Of the remaining horses, 2 were retired and the third was subjected to euthanasia.
Pharyngeal dysfunction in the horse during exercise has been poorly understood. Endoscopic examinations of these animals as they exercised on high-speed treadmills has allowed direct observation of many of these dysfunctions. There is still considerable variation in the interpretation of these findings. The existence and function of the oropharyngeal seal (OPS) is discussed as are several etiological bases for inappropriate pharyngeal function.
A two-year-old Thoroughbred gelding presented eighty-one days after a left-sided prosthetic laryngoplasty (PL). The horse had a continual bilateral foamy ingesta stained nasal discharge as a consequence of dysphagia. An endoscopic examination revealed permanent dorsal displacement of the soft palate (DDSP), which appeared to be associated with a degree of laryngo-pharyngeal mucosal desensitization. The left arytenoid was fixed in a neutral position. It was postulated that the desensitization and thence pharyngeal dysfunction had resulted from surgical trauma to the cranial laryngeal nerve (CLN).
Palatal dysfunction is very common in performance horses. At present, relatively little is known about its aetiology and pathogenesis, although several theories have been proposed. As a result, a multitude of treatments, both conservative and surgical, have been advocated for dorsal displacement of the soft palate (DDSP). This tutorial article aims to provide a comprehensive review of the disorder, discussing aetiopathogenesis, diagnosis and management in turn.
Epiglottic entrapment EE occurred in three forms. Permanent EE and intermittent EE which were diagnosed endoscopically at rest, and more recently intermittent EE diagnosed endoscopically at high speed only. The inclusion of the latter had suggested a greater statistical involvement of EE in cases of respiratory poor performance than had previously been reported. The entrapping mucosas were found to be a varied conglomerate of subepiglottic tissues, and thus the epiglottis was said to be entrapped by subepiglottic mucosas. The shorter, spatulate epiglottis was thought to be more commonly associated with the permanent form of entrapment, while flaccidity of the epiglottis was not associated with EE. The actual process of entrapment was seen to be secondary to the disruption of the airtight seal at the ostium intrapharyngeum. The subepi-glottal mucosas were then exposed to inspiratory negative pressures. A palpable reduction in the retractability of entrapping mucosas may have resulted from chronic intermittent exposure to these inspiratory negative pressures. A number of surgical techniques were available to correct epiglottic entrapment. A particular technique could be selected after considering the factors for and against each procedure. In addition to this, the type of entrapment and available surgical skills were important considerations.
To determine the effects of diode laser palatoplasty on the soft palate in horses.
6 clinically normal horses and 6 euthanized horses from another study.
6 horses underwent diode laser palatoplasty (treated horses); 3 received low-dose laser treatment (1,209 to 1,224 J), and 3 received high-dose treatment (2,302 to 2,420 J). Six other horses received no treatment (control horses). The upper respiratory tracts of all treated horses were evaluated immediately following surgery (day 0) and on days 2, 7, 14, 21, 30, and 45. Horses were euthanized on day 45, and magnetic resonance imaging (MRI) of the head was performed. The soft palate was removed from treated and control horses, evaluated grossly, and scored for edema, inflammation, and scarring. Soft palates from all horses were sectioned for histologic and biomechanical evaluations.
Endoscopic examination revealed a significant increase in soft palate scarring and decrease in edema and inflammation in treated horses by day 7. Gross postmortem findings corresponded with MRI findings. Gross and histologic examination revealed a significant increase in scarring, edema, and inflammation at day 45. Histologic evaluation of palatal tissue from high-dose-treated horses revealed full-thickness injury of skeletal muscle, with atrophy of muscle fibers; findings in low-dose-treated horses indicated superficial injury to skeletal muscle. After surgery, treated horses had a significant decrease in soft palate elastic modulus, compared with control horses.
Laser palatoplasty resulted in soft palate fibrosis and skeletal muscle loss; however, the fibrosis did not result in an increase in soft palate elastic modulus.
To evaluate the occurrence of dorsal displacement of the soft palate (DDSP) during high-speed treadmill (HSTM) exercise in racehorses, and determine treatment efficacy relative to the endoscopic findings observed during resting and HSTM endoscopic examination.
Retrospective study. Animals-Ninety-two racehorses (74 Thoroughbreds, 18 Standardbreds).
The signalment, history (clinical and race), treatments, and video recordings made during resting and HSTM endoscopy were reviewed in 92 racehorses that developed DDSP during HSTM exercise. Only horses that completed 3 starts before and after HSTM examination were included in performance-outcome analysis. Statistical associations were made between the independent variables (the historical findings and the resting and HSTM endoscopic findings) and performance outcome.
Forty-five horses (49%) displaced their palate in an uncomplicated manner, whereas the other horses either had another upper-respiratory abnormality in association with DDSP (35) or displaced after swallowing (12). Although respiratory noise was not recorded during HSTM exercise, only 57 horses (62%) that developed DDSP during HSTM examination had a history of abnormal upper-respiratory noise. For the 45 horses that met the criteria for performance outcome analysis, there were no independent variables recorded during resting or HSTM endoscopy that had a significant association with performance outcome. Treatment for DDSP varied by clinician. Overall, 29 horses (64%) had improved average earnings per start after diagnosis and treatment.
Thirty-five horses (38%) that had DDSP during HSTM endoscopy had no previous history of abnormal upper-respiratory noise, and 74 (80%) had no structural abnormalities noted on resting endoscopic examination.
HSTM examination is an excellent tool for diagnosis of DDSP and the manner in which it occurs. DDSP did not occur similarly in all horses, and was often associated with another upper-respiratory abnormality. Thus, it is unlikely that a single treatment can be applied effectively for all horses that experience DDSP. Both surgical and medical treatments can be beneficial in improving a horse's performance after a diagnosis of DDSP is made. Neither resting nor HSTM endoscopic findings were clearly prognostic.
There has been no objectively assessed case-control study of the efficacy of surgery to correct dorsal displacement of the soft palate (DDSP) previously reported.
Composite surgery has a beneficial result on racing performance in horses affected with DDSP as compared to a matched control population.
Race records were obtained for 53 racing Thoroughbreds which underwent composite staphylectomy, sternothyrohyoideus myectomy and ventriculectomy for correction of idiopathic DDSP at the University of Bristol between 1990 and 1996. Each surgical case was matched for age, sex and training yard with 2 control horses. The racing performance, based on prize money won, of surgical cases and control horses were compared for 3 races run before and after the date of surgery.
Ninety-two percent of the surgical cases returned to racing after surgery. There was a significant increase in earnings of the surgical group before and after surgery (P = 0.011), but there was no significant difference in earnings of the control group before and after the date of surgery (P = 0335). Sixty percent of the surgical group had higher earnings after surgery than before, compared to 40% of controls. When horses which underwent surgery were ranked relative to their 2 matched controls, surgical cases did not significantly change in rank (P = 033), whereas control horses significantly decreased in rank (P = 0.012). Additionally, horses within the surgical group were more likely (P < 0.01) to start in 3 post operative races than those in the control group.
Composite surgery had a beneficial effect on racing performance of horses afflicted with idiopathic DDSP, and further studies to evaluate objectively the usefulness of other surgical techniques are warranted.
To compare racing performance before and after sternothyroideus myotomy, staphylectomy, and oral caudal soft palate photothermoplasty in Thoroughbred racehorses with intermittent dorsal displacement of the soft palate (DDSP).
Retrospective study.
Thoroughbred racehorses (n=102) with DDSP.
Retrieved data included signalment, primary complaint, and upper respiratory tract endoscopic finding. Lifetime race records were compared for earnings per start before and after surgery, days to 1st start, and races won postoperatively.
Comparing mean earnings per start for 3 races before (2792 dollars) and after (3806 dollars) surgery, racing performance improved significantly after surgery in 63% (46/73) of horses that competed in at least 1 race before and after surgery (P=.02). Mean and median days to 1st start after surgery were 109 and 69 days, respectively. Of horses that raced postoperatively 65% (60/92) won at least 1 race, and 77% (71/92) raced in >5 races after surgery.
Sternothyroideus myotomy, staphylectomy, and oral caudal soft palate photothermoplasty significantly improved racing performance in experienced Thoroughbred racehorses with performance limiting DDSP, and overall had a similar outcome to other reported surgical techniques for treatment of DDSP. Clinical Relevance-Sternothyroideus myotomy, staphylectomy, and oral caudal soft palate photothermoplasty should be considered as a surgical approach to correction of DDSP in Thoroughbred racehorses; however, it is possible that staphylectomy may not be necessary to achieve a desirable outcome.
There have been no reports of the efficacy of thermocautery of the soft palate (TSP) assessed objectively as a treatment of intermittent dorsal displacement of the soft palate (DDSP).
To compare: racing performance of horses that underwent thermocautery of the soft palate with matched controls; and 'Racing Post ratings' (RPR) with prize money won (RE) and a performance index (PI) for each of the horses in the study.
Thermocautery of the soft palate has no beneficial effect on racing performance and the 3 measures of performance are significantly related.
The inclusion criteria were fulfilled by 110 horses and each was matched with 2 controls. Changes in performance were compared statistically. RPR, RE and PI were analysed using a regression model.
The percentage of horses that improved in performance following the procedure was 28-51% for the 3 measures of performance, compared to 21-53% for the matched controls. There was no significant effect of the procedure on the changes in RPR or RE. There was a significant effect of the procedure on the change in PI (P=0.015) with more treated horses achieving an improved PI and fewer acquiring a worse PI than matched control horses. The measures of performance showed significant correlation.
Thermocautery of the soft palate alone may not be the most efficacious treatment of DDSP.
Production of a reliable measure of racehorse performance may be possible.
The investigation of a respiratory syndrome herein described as APD, began early in 1983. Between 1983 and 1991,347 horses were examined for poor performance. The study was carried out in conjunction with a variety of surgical techniques, aimed at reducing the incidence of APD. This resulted in a diagnostic protocol which is now used to further explain many cases of respiratory poor performance.
Oral palatopharyngoplasty (OP) is a surgical procedure which was developed to reduce the incidence of DDSP and respiratory poor performance associated with Acquired Pharyngeal Dysfunction (APD).1 Palatine surgery is designed to reduce dorsal billowing of the soft palate, thereby improving nasopharyngeal airway, and thus reducing negative or suction pressures. G. E. mucosal stripping is carried out to improve the stability of ventral positioning of the caudal border of the soft palate. In combination, the two should decrease leakage of oropharyngeal matter passed the isthmus faucium, and reduce the incidence of DDSE Improvements in both respiratory function and performance were encouraging. Post-operative monitoring and management was essential to achieve optimum results. The surgery itself did not interfere with any inherent anatomical function, and hence was void of any debilitating side effects. The state of good health and well-being exhibited by these animals post operatively, became a widely accepted hallmark of the procedure.
Thesis (M.S.)--Michigan State University. Dept. of Large Animal Clinical Sciences, 1987. Includes bibliographical references (leaves 49-57).
Upper airway pressure was measured during maximal exercise in 10 Thoroughbred racehorses with naturally occurring upper airway obstruction. Left laryngeal hemiplegia and arytenoid chondropathy resulted in substantial increases (30-40 cm H2O) in inspiratory upper airway pressure (Pl), whereas complicated aryepiglottic entrapment and subepiglottic cysts produced only modest increases (15 cm H2O) in Pl. Uncomplicated aryepiglottic entrapment and grade IV pharyngeal lymphoid hyperplasia produced only slight increases (3-5 cm H2O). In general, surgical procedures restored airway pressures to within normal limits. Subtotal arytenoidectomy improved but did not normalize airway pressures in horses with arytenoid chondropathy. Pharyngeal lymphoid hyperplasia appeared to have little effect on upper airway function.
Upper airway pressure was measured with a nasotracheal catheter system and a portable pressure transducer in 10 normal horses during maximal exercise before and after left recurrent laryngeal neurectomy. Measurements were repeated 16 weeks after prosthetic laryngoplasty (5 horses) or subtotal arytenoidectomy (5 horses). During maximal exertion, prosthetic laryngoplasty was more effective than subtotal arytenoidectomy in reversing the increases in upper airway pressure that followed left recurrent laryngeal neurectomy.
Fifty-seven Standardbred and 44 Thoroughbred racehorses and 1 Thoroughbred polo mare with primary clinical signs of exercise intolerance or respiratory tract noise or combined exercise intolerance and respiratory tract noise were referred for laser correction of epiglottic entrapment. Significantly (P < 0.001) more Standardbred than Thoroughbred racehorses were affected, compared with the observed hospital population during the same period. At referral, 14 horses did not have evident epiglottic entrapment and were returned to exercise without development of entrapment after treatment, which consisted of 1 week of rest and administration of anti-inflammatory medication.
In 88 standing horses under sedation and topical anesthesia, epiglottic entrapment was corrected transendoscopically by use of a contact neodymium:yttrium aluminum garnet laser. In these 88 horses, 98% of entrapments were persistent, 92% were thick, 97% were wide, and 45% were ulcerated. Thirty-one percent of the horses had endoscopic evidence of epiglottic hypoplasia, and 8% had deviated epiglottic axis.
Complete correction was achieved in 97% of the horses, Persistent dorsal displacement of the soft palate in 1 horse and severe epiglottic hypoplasia with thick, chronic entrapping membranes in 2 horses precluded successful transendoscopic correction with the horses in standing position. Most horses were treated onan outpatient basis, and all were able to be returned to exercise after 7 to 14 days of rest and treatment with anti-inflammatory medication.
Entrapment recurred in 4 horses (5%), 3 of which had hypoplastic epiglottis. Dorsal displacement of the soft palate developed after surgery in 9 horses (10%) and continued in 4 horses (5%) that had displaced soft palate before surgery. All these horses had epiglottic hypoplasia.
Laser correction of epiglottic entrapment in standing horses was safe, well tolerated, and effective. Laser surgery was an alternative to conventional surgery, and eliminated the need for general anesthesia and laryngotomy. It also reduced convalescence and postoperative complications.
Effects of ventriculectomy and prosthetic laryngoplasty on upper airway flow mechanics and blood gas tensions in exercising horses with induced left laryngeal hemiplegia were assessed. Five adult horses were trained to stand, trot (4.5 m/s), and gallop (7.2 m/s) on a treadmill (6.38 degrees incline). Inspiratory and expiratory airflows (VImax, VEmax, respectively) were measured using a 15.2-cm diameter pneumotachograph in a face mask. Inspiratory and expiratory transupper airway pressures (PuI, PuE, respectively) were determined as pressure differences between barometric pressure and lateral tracheal pressure. Blood collected from exteriorized carotid arteries was analyzed for PaO2, PaCO2, pH, hemoglobin (Hb) content, and HCO3- values. Heart rate (HR) was determined with an HR monitor. Measurements were made with horses standing, trotting, and galloping before left recurrent laryngeal neurectomy (LRLN; base line), 14 days after LRLN, 30 days after ventriculectomy (44 days after LRLN), and 14 days after prosthetic laryngoplasty (58 days after LRLN). Before LRLN (base line), increasing treadmill speed for horses from standing to the trot and gallop progressively increased HR, respiratory frequency, VImax, VEmax, PuI, PuE, Hb, and PaCO2 values and decreased PaO2, pH, and HCO3- values; inspiratory and expiratory impedances were unchanged. After LRLN, inspiratory impedance and PuI were significantly (P less than 0.05) increased in horses at the trot and gallop, and PaCO2 was significantly increased in horses at the gallop. The VImax and respiratory frequency were significantly (P less than 0.05) decreased in horses at the gallop. Left recurrent laryngeal neurectomy had no effect on PuE, VEmax, HR, PaO2, pH, Hb, or expiratory impedance values.(ABSTRACT TRUNCATED AT 250 WORDS)
The effect of left laryngeal hemiplegia on airway flow mechanics in 5 exercising horses was examined, and the efficacy of surgical repair by prosthetic laryngoplasty was evaluated. Measurements of the upper airway flow mechanics were made with horses on a treadmill (incline 6.38 degrees) while standing (period A); walking at 1.3 m/s (period B); trotting at 2.6 m/s (period C); trotting at 4.3 m/s (period D); and standing after exercise (period E). Experiments were done on healthy horses before any surgical manipulation (control), at 10 days after left recurrent laryngeal neurectomy, and at least 14 days after prosthetic larynogoplasty. Increasing treadmill speed from period A to period D progressively increased heart rate, respiratory frequency, peak inspiratory flow, and peak expiratory flow, but inspiratory resistance and expiratory resistance remained unchanged. Neither left recurrent laryngeal neutrectomy nor prosthetic laryngoplasty affected heart rate, respiratory frequency, peak expiratory flow, or expiratory resistance when compared with those values at the control measurement periods. Left recurrent laryngeal neurectomy resulted in inspiratory flow limitation at peak inspiratory flow of approximately 25 L/s, and increased inspiratory resistance at periods D and E. Subsequent prosthetic laryngoplasty alleviated the flow limitation and reduced inspiratory resistance at measurement periods D and E.
Laryngeal muscles and nerves were obtained from 42 horses, 3 of which suffered from laryngeal hemiplegia. Of the remaining 39 clinically normal horses, 30% (12) demonstrated pathological changes in the laryngeal musculature.
These changes were indicative of neurogenic atrophy and varied from fibre type grouping only, to marked fascicular atrophy. The muscles affected were those on the left side of the larynx and were supplied by the recurrent laryngeal nerve. Early changes were, however, seen in the muscles on the right side in one case. The main feature of the neural lesion was a distally progressive loss of myelinated nerve fibres, but evidence of segmental demyelination and remyelination was seen in teased nerve fibre preparations. The pattern of the muscle lesion and the possible aetiology of the neuropathy are discussed.
During the years 1971-1979, 127 horses with left laryngeal hemiplegia were studied. The physical characteristics and clinical signs observed in this study were recorded in Part I and Part II of ths series of papers. Of these 127 horses, 81 were treated by the laryngoplasty procedure. Complications of surgery are described and the effects of the operation on respiratory noise and performance are evaluated. In 54.8% of horses the chronic respiratory noise observed during exercise was apparently diminished or eliminated post-operatively. The performance of 44% of horses was apparently improved after surgery. Post-operative racing success occurred in 38% of horses treated. Satisfactory arytenoid adduction as assessed endoscopically within 9 days of surgery was achieved in 77% of cases. Surgical failure appeared to be related to cutting of the laryngeal cartilages by the prosthesis and techniques to minimise this are discussed.
In discussion following, M Laryngoplasty-an evaluation of three abductor muscle prosthetics
- Cosgrove