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Evidence for a central nervous system component of the distal axonopathy associated with equine laryngeal hemiplegia was found in this survey of 33 horses (control, 15; subclinical, 8; clinical, 10). Significantly higher numbers of axonal spheroids were present in sections of the lateral cuneate nuclei in layngeal hemiplegic horses than in those unaffected by the disease.
AIMS: This study was undertaken in order to determine whether wild Burchell's Zebra (Equus burchelli) are affected by Idiopathic Laryngeal Hemiplegia (ILH). ILH has a high prevalence in the domestic horse and a negative control population has not been identified. METHODS: The work was conducted in two phases on two large farms in central Kenya during routine culls. The larynges of 42 zebra were removed and the left and right intrinsic laryngeal adductor and abductor muscles and recurrent laryngeal nerves were isolated. The muscles were weighed and biopsy samples of left and right recurrent laryngeal nerve and cricoarytenoideus lateralis muscles from 16 animals were taken for histological examination. RESULTS: Left adductor muscles were observed to be significantly lighter than right adductor muscles (p = 0.001). There was no significant difference between the weights of left and right laryngeal abductors (p = 0.260). There was no light microscopic evidence of pathological changes consistent with ILH in any of the muscle or nerve samples. CONCLUSIONS: Zebra do not appear to suffer from ILH and equids unaffected by ILH can have significantly lighter muscles on the left of the larynx. CLINICAL RELEVANCE: Mild asymmetries of the larynx on palpation may not be a reliable indicator of ILH. Zebra may be a potentially useful negative control animal for observational ILH studies.
Various competing hypotheses have been put forth to explain how it is possible for patients to be unaware of their own profound weakness. We investigated whether patients' retrospections after resolution of their anosognosia along with their clinical features are consonant with these hypotheses. Three well-educated and articulate men were interviewed about their stroke and their subsequent awareness of weakness. Psychological denial, general cognitive impairment, a faulty superordinate awareness system, lack of knowledge of stroke symptoms, and minimal curiosity as a personality trait were not satisfactory explanations for their anosognosia. Their self-observations and clinical presentations suggest that: (1) anosognosia for hemiplegia can be exquisitely domain-specific; (2) weakness, rather than being perceived automatically, must be discovered; (3) discovery of weakness is impeded by a feedforward intentional deficit which probably interacts with notions of ''body schema'' in complex ways; and (4) awareness of deficit emerges in a graded fashion.
We report three cases of survivors of chronic stroke who were treated with active repetitive movement training of the paretic finger extensors mediated by intramuscular electromyographically controlled neuromuscular electrical stimulation for the purpose of motor relearning. These case reports demonstrate the feasibility of using intramuscular electromyographically controlled neuromuscular electrical stimulation for facilitating the upper limb motor recovery of chronic stroke survivors with mild to moderate hemiplegia.
A study has been made of the pathological changes in the recurrent laryngeal nerves from horses with clinical and sub-clinical idiopathic laryngeal hemiplegia. Qualitative and quantitative studies showed in clinical cases there was a progressive distal loss of large myelinated fibres in the left recurrent nerve. Regenerating clusters and onion bulbs were frequently seen in affected nerves both at proximal and distal levels. Degenerating axons were characterized by collections of organelles, and denervated bands of Bungner were common. Similar but less severe changes were seen in the left recurrent nerve of sub-clinical cases, and in both the clinical and sub-clinical cases the distal right recurrent nerve was also affected. Teased fibre studies showed evidence of chronic demyelination and remyelination. The aetiology of this chronic neuropathy remains uncertain but the possibility of nerve compression is discussed.
OBJECTIVE: The purpose of this study was to examine the influence of laryngoplasty on racing performance and to determine if any of the following variables had a significant effect on outcome: breed (Thoroughbred v Standardbred), endoscopic grade of laryngeal function, ventriculectomy versus no ventriculectomy, type of prosthetic suture used, and number of prostheses placed. STUDY DESIGN: Retrospective study of laryngoplasty with or without ventriculectomy for treatment of left laryngeal hemiplegia in racehorses between 1986 and 1993. ANIMALS OR SAMPLE POPULATION: 230 horses (174 Thoroughbreds, 56 Standardbreds). METHODS: The medical records of racehorses or horses intended for racing were reviewed. Signalment, admitting complaints, physical examination findings, resting endoscopic grade of laryngeal function, type of prosthetic suture material used, number of prosthetic sutures placed, presence or absence of ventriculectomy, and postoperative complications were recorded. RESULTS: Upper respiratory tract noise and exercise intolerance were the most common presenting complaints. Two horses had a laryngeal grade of 2, 109 horses a laryngeal grade of 3, and 119 horses a laryngeal grade of 4. Two double-strand braided polyester sutures were used in 147 horses, a single double-strand polyester suture was used in 49 horses, and a single double-strand nylon suture was used in 34 horses. Ventriculectomy was performed on 186 horses. The most common complication recognized during hospitalization was coughing in 50 horses. Telephone follow-up was obtained for 176 horses. For 168 horses, respiratory noise after surgery was decreased in 126 horses, the same in 28, and increased in 14. After hospital discharge, coughing occurred in 43 of 166 horses, and a nasal discharge occurred in 26 horses. Postoperative racing performance for 167 horses was subjectively evaluated by respondents as being improved in 69% of the horses. Overall owner satisfaction with the outcome after surgery was 81%. Of 230 horses, 178 raced at least one time after surgery. Overall, 117 horses raced three or more times before and after surgery, and 65 of these horses had improved performance index scores. None of the variables of surgical interest affected performance index scores. CONCLUSIONS AND CLINICAL RELEVANCE: Laryngoplasty with or without ventriculectomy allowed 77% of the horses to race at least one time after surgery, improved racing performance in 56% of the horses that completed three races before and after surgery, and improved subjectively evaluated racing performance in 69% of the horses.
OBJECTIVE: To report the effect of unilateral laser vocal cordectomy on respiratory noise and airway function in horses with experimentally induced laryngeal hemiplegia (LH). STUDY DESIGN: Experimental study. ANIMALS: Six Standardbred horses without upper airway abnormalities at rest or during high-speed treadmill exercise. METHODS: Respiratory sounds and inspiratory trans-upper airway pressure (P(Ui)) were measured before (baseline) and 14 days after induction of LH by left recurrent laryngeal neurectomy, and again 30, 60, 90, and 120 days after endoscopically assisted laser cordectomy of the left vocal cord. Data were collected with the horses exercising on a treadmill at a speed producing maximum heart rate (HR(max)). RESULTS: In horses exercising at HR(max), induction of LH caused a significant increase in P(Ui), sound level (SL), and the sound intensity of formant 2 (F(2)) and 3 (F(3)). The sound intensity of formant 1 (F(1)) was unaffected by induction of LH. Laser vocal cordectomy had no effect on SL, or on the sound intensity of F(1) and F(3). At 30, 60, 90, and 120 days after surgery, P(Ui) and the sound intensity of F(2) were significantly reduced, but these variables remained significantly different from baseline values. CONCLUSIONS: Unilateral laser vocal cordectomy did not effectively improve upper airway noise in horses with LH. The procedure decreased upper airway obstruction to the same degree as bilateral ventriculocordectomy. CLINICAL RELEVANCE: Currently, laser vocal cordectomy cannot be recommended for the treatment of upper airway noise in horses with LH.
The medical records of 80 horses treated for left laryngeal hemiplegia by prosthetic laryngoplasty, ventriculectomy and vocal cordectomy were examined, first to compare the subjective and objective success rates for groups of horses of different ages and used for different purposes, and secondly, to compare the efficacy of including vocal cordectomy in the surgical protocol with published success rates for laryngoplasty and ventriculectomy alone. Subjectively, 70 per cent of the horses were said to have had a successful surgical outcome. The success rate for thoroughbred racehorses (66 per cent) was lower than for other breeds (90 per cent) on the basis of a subjective assessment by owners and trainers. Thoroughbreds two years old or younger had a success rate of 69 per cent, but older thoroughbreds had a success rate of 61 per cent. Of the 17 horses for which an objective performance index could be calculated, 10 (59 per cent) had an improved performance postoperatively. There was a nearly significant association between the objective and subjective assessments (P=0.078). Six of 69 horses (8.7 per cent) continued to make a respiratory noise after surgery. The subjective assessment of success did not appear to correlate with the objective measure of success used in this study and age had no apparent association with a successful surgical outcome. Inclusion of a vocal cordectomy in the surgical protocol may be more important in the eradication of postoperative respiratory noise than in improving clinical success rates.
Laryngeal hemiplegia (LH) is the most common disorder of laryngeal motility. It is deemed not to cause obstruction of the upper airway; in fact, the main symptoms are dysphonia and breathiness, and respiratory impairment is not commonly reported. The aim of this study was to objectively assess upper airway patency in 41 patients affected by LH (mean age, 54.4 +/- 15.2 years; 27 female) and 30 controls (mean age, 50.0 +/- 16.1 years; 19 female) by means of flow-volume loop spirometry and body plethysmography to measure specific airway resistance (sRaw) at increasing respiratory frequencies. The causes of LH were cervical surgery (28), tumor infiltration (5), and unexplained (8). None of the patients or controls was affected by lower airway disease. Spirometry showed that the patients had inspiratory flows (PIF, FIF50) significantly lower than those of the controls (p < .0001), whereas the expiratory flows (FEV1, FEF50) were normal, with the exception of peak expiratory flow (PEF), which was reduced, especially in female patients. The mean FEF50/FIF50 ratio (about unity in the normal subjects) was >1, as is typical of variable extrathoracic obstruction. Plethysmography showed that the values of sRaw of the LH group were not statistically different from those of the controls at 30 +/- 5 breaths per minute, but they progressively and significantly increased at 60 +/- 5 (p < .01) and 90 +/- 5 breaths per minute (p < .002), whereas no significant sRaw change was observed in the controls. These results show that LH causes obstruction of the upper airway that can be assessed and quantified by means of spirometry and body plethysmography. A dynamic narrowing due to inspiratory medialization of the paralytic vocal fold and flow turbulence during hyperventilation seem to be the causes of patency impairment. The flow-volume loop is an excellent, inexpensive, and easily available means of functionally evaluating upper airway obstruction, but some patients have difficulty in performing an inspiratory test that requires maximal effort, and the flow reduction during forced ventilation may be partially due to the effort dependency of the tests themselves. Plethysmographic assessment of airway resistance may be a valid alternative or complement, as it reveals an increase in sRaw at increasing respiratory frequencies.
For equinus deformity in spastic hemiplegia, correction by the White slide technique has been studied in a group of 35 patients followed up for 14 to 20 years. It is a simple, effective method of lengthening the calcaneal tendon, and is free from significant complications with an acceptable rate of recurrent deformity. The majority of patients achieved a heel-toe gait.
Videoendoscopy of the larynx during treadmill exercise was used to determine the surgical treatment of upper airway obstruction in a Standardbred colt. Surgical correction of right-sided laryngeal hemiplegia, first by laryngoplasty, then subtotal arytenoidectomy, was ineffective. Videoendoscopy indicated, and upper airway flow mechanics confirmed, that the laryngeal opening was adequate at rest, but obstruction occurred during exercise. On the basis of the appearance of the larynx during high airflow rates on slow-motion playback of the videorecording, total arytenoidectomy was performed, which permitted the horse to race successfully. Videoendoscopy of the upper airway during exercise accurately predicted airflow impedance and permitted salvage of this racehorse, indicating that this is a practical, useful technique that will improve evaluation of upper airway obstructions in the horse.
Left laryngeal hemiplegia was induced by resection of the left recurrent laryngeal nerve in 12 dogs. A neuromuscular pedicle graft formed from the first cervical nerve and sternothyroideus muscle was transplanted after 1 week to the denervated cricoarytenoideus dorsalis muscle in 8 dogs. The remaining 4 dogs served as controls. Left arytenoid abduction was blindly evaluated by laryngoscopy with video photography at time 0, at 1 week, and at 19 weeks in all dogs. At 19 weeks, biopsy specimens of the left cricoarytenoideus dorsalis muscle and the neuromuscular pedicle were taken from 4 of the treatment dogs, and biopsy specimens of the left cricoarytenoideus dorsalis muscle were taken from the 4 control dogs. All biopsy specimens were blindly evaluated by histologic and histochemical examination. At 36 to 44 weeks, the remaining 4 treatment dogs, from which biopsy specimens had not been taken, were reevaluated by use of laryngoscopy with video photography. Complications and difficulties encountered during surgery included hemorrhage in the area of the cricoarytenoideus dorsalis muscle, location of a branch of the first cervical nerve that was long enough to prevent tension at the graft site, orientation of the muscle pedicle in the cricoarytenoideus dorsalis muscle without the use of an operating microscope, and preservation of the terminal portion of the first cervical nerve while forming the neuromuscular pedicle. Results of the arytenoid movement evaluations revealed improvement in arytenoid abductor function in the treatment group, compared with that in the control group at 19 weeks. Arytenoid abduction in the treatment group at this time, however, was still significantly decreased (P less than 0.05), compared with presurgical movement evaluations.(ABSTRACT TRUNCATED AT 250 WORDS)
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.
Arterial blood samples were collected during maximal exercise over 1.6 km in a thoroughbred horse with left laryngeal hemiplegia. Acid-base and blood gas measurements were performed on each sample and compared to the results from samples which were similarly collected 48 hours after laryngoplasty surgery was performed. Before surgery, the PaO2 was 53.2 mm Hg and the PaCO2 was 58.1 mm Hg after 1.6 km. After surgery, the corresponding results were 83.6 mm Hg (PaO2) and 39.0 mm Hg (PaCO2). There was no significant difference in the times taken for each gallop. The exercise intolerance associated with laryngeal paralysis may be caused by an increase in the oxygen cost of breathing.
Medical records of 70 horses diagnosed with left laryngeal hemiplegia that were treated by use of prosthetic laryngoplasty combined with bilateral ventriculectomy were examined. Degree of arytenoid cartilage abduction that had resulted from the prosthesis had been graded before the horse was discharged from the hospital. Follow-up information through owner/trainer questioning was acquired for 55 horses. Information concerning the type and frequency of complications, if any, was recorded, along with a determination of owner/trainer satisfaction regarding surgical results. Race records were acquired for 42 horses and were used to aid in evaluation of postoperative performance. After surgery, Thoroughbred racehorses had a much lower success rate (48%; 19 of 40 horses), determined from owner/trainer questioning, than did all breeds in the study that were not intended for racing (93%; 14 of 15 horses). Younger Thoroughbred race-horses had a better success rate (70%; 14/20) than did those > or = 3 years old (25%; 5/20). Degree of arytenoid abduction had little effect on outcome, except that horses with maximal abduction (grade 5) of the arytenoid cartilage had a higher prevalence of complications and poor correction. The 2 most prevalent complications were exercise intolerance (42%; 23 of 55 horses) and continuing noise when exercising (47%; 26 of 55 horses).
Laryngoscopic examination during sedation was performed on 24 stallions and on their offspring (240 foals and 474 adult horses). Additionally the dams (n = 308) of 35 foals and 216 horses were examined. With the bilateral comparison of the arytaenoid movements the function of the abductory and adductory laryngeal muscles were evaluated and the left abductory dysfunction (idiopathic laryngeal hemiplegia, ILH) was divided into six degrees. The incidence and degree of ILH depended on age and the occurrence of the same dysfunction in the parents. Foals suffered in significantly lower number (24.7 per cent) than adult horses (49.7 per cent). The progeny of unaffected parents suffered significantly less from ILH (8.9 per cent of the foals, 39.6 per cent of the adult offspring) than did comparable progeny of affected parents (41 per cent of the foals, 60.9 per cent of the adult offspring). There was no correlation between the occurrence of ILH and sex. 120 horses were examined laryngoscopically and during work to get an information about the correlation between a visible ILH and the appearance of a typical inspiratory noise. 54.3 per cent of the horses with ILH had a typical inspiratory noise. 80.9 per cent of the horse with a typical inspiratory noise showed ILH.
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