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Keywords:

  • horse;
  • anaesthesia;
  • facial nerve paralysis;
  • electrostimulation

Summary

  1. Top of page
  2. Summary
  3. Introduction
  4. Case history
  5. Clinical findings and diagnosis
  6. Treatment
  7. Outcome
  8. Discussion
  9. Conclusions
  10. Authors' declaration of interests
  11. References

This Case Report describes a 5-year-old Standardbred gelding that was referred to the Equine Hospital of ONIRIS Veterinary School of Nantes, France for a surgical procedure under general anaesthesia. Anaesthesia was induced and maintained intravenously and the horse was placed in left lateral recumbency with a padded halter. On post operative Day 1, a post anaesthetic distal facial nerve branch paresis was diagnosed based on clinical signs. The horse was discharged on post operative Day 2 with medical treatment based on anti-inflammatory drug administration locally and systemically. The horse was re-examined 2 weeks after the surgery; the left partial facial paralysis was still present and associated with amyotrophy of the muscles supplied by the buccal branches of the facial nerve. In accordance with the owner, the horse was hospitalised to start an electrostimulation treatment. The horse was treated every day for the first 4 days, then every 2 or 3 days during the following 3 weeks, for a total of 11 sessions. At the end of the second week of treatment, the horse was able to normally prehend the food and atrophy seemed reduced. The horse was discharged from hospitalisation at the end of the third week of treatment with specific recommendations. One month after discharge from the hospital just a slight asymmetry could be noticed at rest. Six months later, the training season began and the horse was able to perform. Facial paralysis due to nerve compression is a well-known complication of anaesthesia. Gradual recovery of function over the weeks of treatment suggests that electroacupuncture may promote recovery and may hasten time of recovery.


Introduction

  1. Top of page
  2. Summary
  3. Introduction
  4. Case history
  5. Clinical findings and diagnosis
  6. Treatment
  7. Outcome
  8. Discussion
  9. Conclusions
  10. Authors' declaration of interests
  11. References

Facial nerve paralysis has been identified in several domestic species (DeLahunta and Glass 2009). The most common cause in horses is a facial nerve traumatic injury, which can be a consequence of direct trauma to the nerve or a result of local inflammatory changes involving the nerve (Sumano et al. 1997; Rose and Hodgson 2000). It may improve over days, weeks or months without treatment, but can also persist for months to years and lead to inability to perform (Jeong et al. 2001; Smith and George 2009). In man, there is some evidence to support acupuncture as a treatment for facial paralysis (Dong and Xie 2002; Mayor 2007). Electroacupuncture has been regarded as a therapeutic option for various muscular and neurological conditions and may also be able to facilitate the treatment of facial paralysis in horses (Sumano et al. 1997; Fleming 2001; Kim and Xie 2009). Electroacupuncture elevates neurotrophic factors such as neurotrophine 3 (NT-3) and level of cyclic adenosine monophosphate in injured spinal cord tissue (Ding et al. 2009). Neurotrophine 3 plays an important role in nervous system development, neuronal survival and differentiation, and neural repair. Elevated NT-3 expression can improve the microenvironment of injured spinal cord (Yan et al. 2011). In addition, a previous study reported that electroacupuncture treatment can prevent the formation of a glial scar after spinal cord injury (Yang et al. 2005). More interestingly, regarding functional peripheral nerve regeneration it has been shown that electroacupuncture exerts a positive influence on motor recovery and reduced pain related behaviour in mice after sciatic nerve crush injury (Hoang et al. 2012). This clinical case reports the use of electrostimulation in the treatment of traumatic partial facial nerve palsy following a surgery under general anaesthesia in a horse.

Case history

  1. Top of page
  2. Summary
  3. Introduction
  4. Case history
  5. Clinical findings and diagnosis
  6. Treatment
  7. Outcome
  8. Discussion
  9. Conclusions
  10. Authors' declaration of interests
  11. References

A 5-year-old Standardbred gelding was referred for surgical release of an epiglottic fold entrapment to the Equine Hospital of ONIRIS Veterinary School of Nantes, France. The surgery was performed under general anaesthesia with the horse placed in left lateral recumbency in a padded recovery box. Anaesthesia was induced intravenously with diazepam (Valium)1 at 0.05 mg/kg bwt and ketamine (Imalgene)2 at 2.2 mg/kg bwt after a romifidine premedication (Sedivet)3, at 0.08 mg/kg bwt and maintained by administration of a triple drip (guaifenesin 5%, ketamine 1 g/l, romifidine 0.05 g/l). The surgical site was accessed by the oral cavity and the procedure was performed under endoscopic guidance. No intraoperative complications were encountered. The procedure lasted 18 min and the total recumbency duration lasted 60 min. During the procedure, a padded halter was kept on the horse in order to mobilise the head easily and was left during recovery.

Clinical findings and diagnosis

  1. Top of page
  2. Summary
  3. Introduction
  4. Case history
  5. Clinical findings and diagnosis
  6. Treatment
  7. Outcome
  8. Discussion
  9. Conclusions
  10. Authors' declaration of interests
  11. References

On post operative Day 1, the horse presented a marked muzzle deviation towards the right side, the left nostril was collapsed and sagging inwards during inspiration. The lower lip on the left side hung loosely from its attachment and the horse had difficulty prehending food. The left eyelid and the left ear did not show any weakness. Additionally, swelling was present on the left lateral aspect of the masseter at the level of the facial nerve buccal branches. A traumatic distal facial nerve branch paresis was diagnosed based on clinical signs (Fig1). The initial treatment was comprised of a single i.v. administration of dexamethasone (Dexadreson)4 at 0.1 mg/kg bwt and local application twice a day of a topical gel containing dimethyl sulfoxide and prednisolone. The horse was discharged on post operative Day 2. The owner was instructed to administer a 5-day course of phenylbutazone (Equipalazone)4 at 2.2 mg/kg bwt per os s.i.d., to rest the horse for 2 weeks (1 week of box rest and 1 week in the paddock), and to return for follow-up.

figure

Figure 1a) and b). The horse with distal facial nerve palsy associated with a marked muzzle deviation towards the right side and the lower lip on the left side hung loosely.

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The horse was re-examined 2 weeks after the surgery for a post operative evaluation of the upper airway and the facial paralysis. The left partial facial paralysis was still present and a discrete amyotrophy of the muscles supplied by the buccal branches of the facial nerve (levator nasolabialis, orbicularis oris, levator labii superioris, caninus, depressor labii inferioris, buccinator, zygomaticus) was noted by comparative palpation of the muscles on both sides of the face (Fig2). Food impaction in the left cheek and drooling on the left side of the lips had worsened. Cranial nerve testing did not reveal any additional abnormalities apart from the left distal facial nerve. Muscle tone and movements of the left eyelid and the left ear were deemed normal. Endoscopic examination of the upper airway including the left guttural pouch did not show any abnormality and confirmed the resolution of the epiglottic entrapment with normal healing at the surgical site.

figure

Figure 2. Superficial structures of the head; the course of the facial nerve and muscles supplied by its buccal branches.

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Treatment

  1. Top of page
  2. Summary
  3. Introduction
  4. Case history
  5. Clinical findings and diagnosis
  6. Treatment
  7. Outcome
  8. Discussion
  9. Conclusions
  10. Authors' declaration of interests
  11. References

Due to a lack of spontaneous recovery of the paresis and the identification of muscle atrophy, the horse was hospitalised to start an electrostimulation treatment.

The acupuncture points were selected in accordance to veterinary literature and adapted to the course of the facial nerve on this horse (Fleming 2001; Jeong et al. 2001; Mayor 2007). The electroacupuncture unit used was an IC-1107+5 (Fig3) that has 3 output channels device, an adjustable frequency 0–500 Hz, an asymmetric biphasic pulse shape with a phase duration of 100 μs on low voltage (0–10 V) and a low current amplitude (0–20 mA). Needles (Serein 0.25 × 40 mm)6 used were single-use, sterile, silicon coated individually packaged acupuncture needles. They were inserted just under the skin or directly into the muscle. Needles were attached by lead clip to the electroacupuncture unit. The thinness of the skin facilitated the palpation of the buccal branches. For the first 3 sessions, the acupoints TH17, ST4, 6 and 7 were used bilaterally (Table1). Extra needles were inserted subcutaneously along the dorsal and the ventral buccal branches on the left side and intramuscular needles were inserted in the levator labii superioris, the caninus and the depressor labii inferioris muscles (Fig4). In the following sessions, TH17 and ST7 were treated bilaterally. Two or 3 points along each buccal branch were selected on only the left side. Three leads were used for the electrostimulation (ITO ES-130): one lead on each facial buccal branch and one lead in the muscle (alternating every 5 min between the caninus, orbicularis, levator labii superioris and depressor labii inferioris muscles), for the first 3 treatments. Once nerve conduction had fully returned (Treatment 4), stimulation of each buccal branch was used to elicit muscle contractions of the nostril, upper and lower lips (Fig4). Electrostimulation lasted 20 min with alternating frequencies every 5 min between 5 and 200 Hz with a low current intensity. A frequency of 1.5 Hz was used for repeated muscle contractions for periods of 2–3 min 3 times during the treatment. Each treatment from the fourth session onward included a few short provoked tetanic contractions (1–2 s, <10 in a row) of the nostril-upper lip and the lower lip by stimulation of each branch. Needle insertion was always very well tolerated as well as low intensity electrostimulation. Induced tetanic contractions elicited a large head movement during the first applications but slowly increasing the intensity of stimulation resolved the initially observed discomfort. The horse was treated every day for the first 4 days, then every 2 or 3 days during the following 3 weeks, for a total of 11 sessions. During the second week, physical therapy was used in conjunction with the acupuncture therapy; presenting hay to the left side of the mouth at least 3 times a day to stimulate active mobilisation of the left side of the lips for 10 min and daily grazing in the paddock facilitated mobilisation of the affected muscle (Table2).

figure

Figure 3. The electroacupuncture unit, IC-1107+.

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figure

Figure 4. Electroacupuncture treatment of a horse with left distal facial paralysis and localisation of the acupuncture points used in the treatment.

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Table 1. Description of acupuncture points used
Point, Chinese nameMeridianLocation area
ST4, Di CangStomach meridianCaudal to the corner of the mouth, at the ‘V’ junction of the levator nasolabialis m. and zygomaticus m., on the outer margin of the orbicularis muscle.
ST6, JiacheStomach meridianIn the centre of the masseter muscle belly, just dorsal to the ventrolateral aspect of the jaw. Located in a depression when the jaw is opened (where the ring halter is).
ST7, Xia GuanStomach meridianAt the temporo-mandibular joint, ventral to the zygomatic arch, caudodorsal to the lateral canthus, in the masseter m.
TH17, Yi FengTriple heaterPosterior to the ear in depression between the mandible and mastoid process.
Table 2. Therapeutic table
Type of treatmentDay after surgeryDetailed description
Medical

D1

D1–D5

  • Dexamethasone (Dexadreson, i.v.)4 at 0.1 mg/kg bwt, s.i.d.
  • Topical gel (dimethyl sulfoxide, prednisolone), b.i.d.
  • Phenylbutazone (Equipalazone)4 2.2 mg/kg bwt per os, s.i.d.

Acupuncture

First week

D16, D17, D18AcupointsExtra needlesLeadsMode and frequency
BilaterallyLeft sideLeft sideTreatment duration: 20 min
TH17, ST4, ST6, ST7

Subcutaneously

Along the dorsal and the ventral buccal branches

Intramuscular needles

(Levator labii superioris, caninus, depressor labii inferioris)

One lead on needles placed along left dorsal branch

One lead on needles placed along left ventral branch

One lead on intramuscular needles (levator labii superioris, caninus)

  • Alternating every 5 min
    • (5–200 Hz)
Second and third weekD19, D21, D23, D25, D28, D31, D34, D37TH17 and ST7
  • Along the dorsal and the ventral buccal branches with the proximal needle just caudally to the origin of the branches and the distal needle proximal to the rostral border of the masseter

One lead on needles placed along left dorsal branch

One lead on needles placed along left ventral branch

  • Alternating every 5 min
    • (5–200 Hz)
  • Low current intensity
  • 1.5 Hz for repeated muscle contractions for periods of 2–3 min, 3 times during the treatment
Physical therapyD23 to the endHay presentation by hand of the left side to stimulate mobilisation of the affected muscles for 10 min, t.i.d. and all day grazing.

Outcome

  1. Top of page
  2. Summary
  3. Introduction
  4. Case history
  5. Clinical findings and diagnosis
  6. Treatment
  7. Outcome
  8. Discussion
  9. Conclusions
  10. Authors' declaration of interests
  11. References

After the 4 first treatments, the horse exhibited an improved ability to drink and feed with less cheek impaction and reduced drooling at the left commissure. Weak spontaneous movements of the upper lip were noticed at the end of the first week and facial asymmetry diminished progressively over the 3-week course of treatment. At the end of the second week of treatment, the horse was able to normally prehend the food with his left side of the lips. Atrophy seemed reduced and the food impaction had disappeared. The horse was discharged from hospitalisation at the end of the third week with instruction to keep promoting food prehension on the left side of his lips twice daily for one month. One month after discharge from the hospital, a slight asymmetry could be noticed at rest but disappeared while the horse was mobilising his lips. The horse's training season began 6 months after the treatment and no exercise intolerance was observed. Furthermore, the left nostril appeared to dilate normally at exercise.

Discussion

  1. Top of page
  2. Summary
  3. Introduction
  4. Case history
  5. Clinical findings and diagnosis
  6. Treatment
  7. Outcome
  8. Discussion
  9. Conclusions
  10. Authors' declaration of interests
  11. References

In horses, traumatic facial paralysis is a well-known complication of abnormal pressure applied to the face over the track of the facial nerve. Predisposing factors include anatomic features in the horse, such as the nerve passing over prominent facial bony structures (rim of the ramus mandibulae, supraorbital ridge) and nerve location in thin subcutaneous tissue as well as prolonged periods of complete lateral recumbency on hard surfaces or wearing a halter with large buckles and thick leather or fabric (DeLahunta and Glass 2009; Smith and George 2009). Despite padding precautions and a short duration of recumbency, facial paralysis developed in this horse and was probably a result of keeping a large, thick and insufficiently padded halter on the head.

The World Health Organisation has included Bell's palsy in its list of diseases for which acupuncture therapy is indicated and a wide variety of human facial paralyses are commonly treated by acupuncture and electroacupuncture (Dong and Xie 2002; Mayor 2007). Point selection based on traditional acupoints has been shown to be more effective when it is adapted to the anatomical distribution of the facial nerve branches and anatomical location of muscles targeted for stimulation (Fleming 2001; Jeong et al. 2001; Mayor 2007). In the treatment of various problems including paralysis, electroacupuncture, as compared to simple needling, has been shown to allow for more rapid, more intense and longer lasting results (Mayor 2007). While experimental data have supported the benefit of electrical nerve stimulation for axonal regeneration following nerve trauma (Shi et al. 2000), direct stimulation of denervated muscles has been a subject of controversy. Excessive stimulation and movement of muscles with reduced circulation is thought to increase fibrosis and delay nerve regrowth and reconnection to muscles (Mayor 2007). However, electrical stimulation by its beneficial effects on microcirculation and inflammation can improve tissue nourishment and healing as well as delay atrophy and fibrosis. Selection of electrical parameters based on intrinsic firing characteristics of motor units themselves like in trophic electrical stimulation (low frequencies and amplitudes) appears to be less fatiguing and more able to maintain muscle tone by altering metabolism rather than muscle fibre training (Mayor 2007). Low frequency and low intensity stimulation for short periods of time were therefore initially used to obtain weak contractions of atrophied muscle in this horse. Once nerve conduction had been regained, alternating high and low frequency stimulation at low amplitude was used as it has been shown to be more efficacious than a continuous stimulation at a set frequency (Mayor 2007). This constitutes a difference with the stimulation mode used by Sumano in his 12 clinical cases.

When the injury is mild, clinical signs often disappear in a few days/weeks and it is thought that no nerve degeneration occurs, only interruption of nerve conduction (neuropraxia). The myelin sheath is temporarily damaged causing a focal demyelination and a partial denervation of the muscles, which can still be excited by stimulation of the motor nerve (Mayor 2007). If the lesion is more severe (neurotmesis), a complete denervation leads to muscle degeneration and fibrosis starting within 1–2 weeks of the nerve injury and is completed in about 3 years. In this sort of clinical case, the muscle fibres need to be directly stimulated to contract. The severity of the lesion was not clearly established; however, absence of spontaneous recovery and muscle atrophy seems to be in favour of neurotmesis. Rapid recovery of nerve conduction as identified by muscle contraction elicited by stimulation of the nerve on the third treatment probably indicates a less severe lesion than initially assessed. Electroacupuncture treatment is believed to have been beneficial in this case as observed by the recovery and improvement of clinical signs over time. No improvement was seen during the first 2 weeks with the initial medical treatment and facial muscle atrophy had begun. Gradual recovery of function over the 3-week electroacupuncture course suggests that it is a favourable treatment. Sumano et al. (1997) reported successful outcomes with a similar treatment course: first stimulation within the 10 days (2 weeks for this case) following paralysis onset with a mean of 13 (7–17) treatments done every other day over a course of 3–4 weeks (11 sessions over 3 weeks for the present case). Progressive improvements were seen over the course of the treatment and very visible after the first or second treatment as in the present case. Although the factors involved in the decision of treatment termination are not clearly stated, owner satisfaction seemed to have played an important role. Follow-up at 6 months showed no recurrence of clinical signs in both case reports. Rehabilitation exercises were added to the electroacupuncture for the present case during the second week of treatment and likely also played a role in recovery. Human and experimental data show that there are advantages in combining electrotherapy and physiotherapy (Angelov et al. 2007; Mayor 2007).

Conclusions

  1. Top of page
  2. Summary
  3. Introduction
  4. Case history
  5. Clinical findings and diagnosis
  6. Treatment
  7. Outcome
  8. Discussion
  9. Conclusions
  10. Authors' declaration of interests
  11. References

Distal facial paralysis in the horse as described in the present case affects food prehension ability and nostril dilation. It can result in dysphagia and inability to perform. Spontaneous recovery can be long and incomplete, jeopardising an athletic career. The use of electrotherapy seems advantageous in promoting recovery and may hasten time of recovery. However, as the amount of nerve injury was not assessed before treatment and a multimodal therapeutic approach was used, it is not possible to determine which part of the treatment was the most efficacious, although the treatment success was assumed to be due to the combined therapy (electroacupuncture and physical therapy) after initial medical treatment failed. Finally, it is important to keep in mind that facial paralysis might occur even after a short lateral recumbency and halters should be always removed when possible. Discussion about appropriate positioning and padding to avoid nerve lesion is the primary way to avoid facial paralysis in horses undergoing general anaesthesia.

Manufacturers' addresses
  1. 1

    Roche, Boulogne-Billancourt, France.

  2. 2

    Merial, Lyon, France.

  3. 3

    Boehringer Ingelheim, Paris, France.

  4. 4

    MSD, Courbevoie, France.

  5. 5

    ITO, Tokyo, Japan.

  6. 6

    Seirin Corporation, Shizuoka, Japan.

References

  1. Top of page
  2. Summary
  3. Introduction
  4. Case history
  5. Clinical findings and diagnosis
  6. Treatment
  7. Outcome
  8. Discussion
  9. Conclusions
  10. Authors' declaration of interests
  11. References
  • Angelov, D.N., Ceynowa, M., Guntinas-Lichius, O., Streppel, M., Grosheva, M., Kiryakova, S.I., Skouras, E., Maegele, M., Irintchev, A., Neiss, W.F., Sinis, N., Alvanou, A. and Dunlop, S. (2007) Mechanical stimulation of paralyzed vibrissal muscles following facial nerve injury in adult rat promotes full recovery of whisking. Neurobiol. Dis. 26, 229-242.
  • Delahunta, A. and Glass, E. (2009) Lower motor neuron: general somatic efferent, cranial nerve. In: Veterinary Neuroanatomy and Clinical Neurology, Eds: A. Delahunta , E. Glass and M. Kent , W.B. Saunders, St Louis. pp 134-167.
  • Ding, Y., Yan, Q., Ruan, J.W., Zhang, Y.Q., Li, W.J., Zhang, Y.J., Li, Y., Dong, H. and Zeng, Y.S. (2009) Electro-acupuncture promotes survival, differentiation of the bone marrow mesenchymal stem cells as well as functional recovery in the spinal cord-transected rats. BMC Neurosci. 10, 1-13.
  • Dong, H.G. and Xie, Z.F. (2002) Acupuncture: review and analysis of reports on controlled clinical trials. World Health Organisation, Geneva.
  • Fleming, P. (2001) Acupuncture for musculoskeletal and neurologic conditions in the horse. In: Veterinary Acupuncture: Ancient Art to Modern Medicine, Ed: A.M. Schoen , Mosby, St Louis. pp 443-465.
  • Hoang, N.S., Sar, C., Valmier, J., Sieso, V. and Scamps, F. (2012) Electro-acupuncture on functional peripheral nerve regeneration in mice: a behavioural study. BMC Complement. Altern. Med. 12, 1-9.
  • Jeong, S.M., Kim, H.-Y., Lee, C.-H., Kweon, O.K. and Tam, T.C. (2001) Use of acupuncture for the treatment of idiopathic facial nerve paralysis in a dog. Vet. Rec. 148, 632-633.
  • Kim, M.S. and Xie, H. (2009) Use of electroacupuncture to treat laryngeal hemiplegia in horses. Vet. Rec. 165, 602-603.
  • Mayor, D.F. (2007) Electroacupuncture: an introduction and its use for peripheral facial paralysis. J. Chin. Med. 84, 1-19.
  • Rose, R.J. and Hodgson, D.R. (2000) Neurology. In: Manual of Equine Practice, 2nd edn., W.B. Saunders Company, An Imprint of Elsevier, Philadelphia. pp 503-576.
  • Shi, X., Yu, G. and He, D. (2000) An experimental study on physiotherapy for traumatic facial nerve injury. Zhonghua Kou Qiang Yi Xue Za Zhi 35, 450-452.
  • Smith, M.O. and George, L.W. (2009) Diseases of the nervous system. In: Large Animal Internal Medicine, 4th edn., Ed: B.P. Smith , Mosby, St Louis. pp 972-1111.
  • Sumano, H., Mateos, G. and Hoyos, L. (1997) The use of electroacupuncture for the management of unilateral traumatic facial paralysis in the horse: preliminary report. Am. J. Acupunct. 25, 169-174.
  • Yan, Q., Ruan, J.W., Ding, Y., Li, W.J., Li, Y. and Zeng, Y.S. (2011) Electro-acupuncture promotes differentiation of mesenchymal stem cells, regeneration of nerve fibers and partial functional recovery after spinal cord injury. Exp. Toxicol. Pathol. 63, 151-156.
  • Yang, C., Li, B., Liu, T.S., Zhao, D.M. and Hu, F.A. (2005) Effect of electroacupuncture on proliferation of astrocytes after spinal cord injury. Zhongguo Zhen Jiu 25, 569-572.