Clinical communication — Kliniese mededeling

Nuchal crest avulsion fracture in 2 : a cause of headshaking

A Voigta, M N Sauleza* and C M Donnellana

ally to the 1st larger opacity. The nuchal ABSTRACT crest appeared irregular and was sus- The medical records of 2 horses that developed headshaking after blunt pected to be the corresponding fracture trauma to the occipital region are reviewed. The history, signalment, clinical signs, diagnostic bed. methods, diagnosis and treatment were recorded in each case. Both horses displayed head- Ultrasonographic examination was shaking, while one repeatedly lifted its upper lip and pawed excessively at the performed of the nuchal ligament with a ground. In both horses, diagnostic imaging of the occipital region revealed avulsion fragments 7.5 MHz T-Piece linear array multi- of the nuchal crest and a nuchal desmitis in association with hyperfibrinogenaemia. The frequency transducer. The right nuchal presence of an avulsion fragment of the nuchal crest with associated nuchal desmitis ligament had a 23 × 8.4 mm, diagonally should be considered in horses presenting with headshaking and may respond favourably up to 18 mm, hyperechoic line which cast to conservative therapy. a clean acoustic shadow 28 mm caudally Keywords: equine, headshaking, nuchal crest desmitis, trauma. to the nuchal crest. An additional 2.7 mm Voigt A, Saulez M N, Donnellan C M Nuchal crest avulsion fracture in 2 horses: a cause smaller structure could be seen 8 mm of headshaking. Journal of the South African Veterinary Association (2009) 80(2): 111–113 (En.). cranially to the large one. The right Department of Companion Animal Clinical Studies, Equine Internal Medicine, Faculty of nuchal ligament measured 1.07 cm2 vs Veterinary Science, Private Bag X04, Onderstepoort, 0110 South Africa. 0.69 cm2 on the left. The nuchal ligament on the right lost its homogenous appear- ance and the ligament fibres appeared to INTRODUCTION racehorse developed acute onset be hypoechoic. Although headshaking is a widely of spontaneous and repetitive vertical, Following interpretation of diagnostic recognised disorder, a precise aetiology horizontal and rotary movement of his imaging results, avulsion fragments of the is seldom found and treatment is often head and neck of 3-week duration. The nuchal crest, with an associated nuchal unrewarding. The purpose of this case headshaking varied in intensity through- desmitis caused by suspected blunt report is to review the clinical records of 2 out the day and occurred both at rest and trauma to the occipital region constituted horses that developed headshaking after during exercise. A lateral radiograph the most significant finding. Serum bio- blunt trauma to the occipital region with (Fig. 1) of the occipital region revealed chemical analysis revealed hyperfibrino- resultant nuchal crest avulsion fracture a 22 × 15 mm mushroom-shaped trabe- genaemia (7 g/ , reference range <4 g/ ) and associated nuchal desmitis. The sig- culated mineral opacity visible 30 mm which may have been due to inflamma- nificance of the abnormalities was con- caudal to the nuchal crest with an addi- tion of the nuchal ligament. firmed by the infiltration of a local tional 6 mm opacity located 10 mm crani- The gelding was managed with anaesthetic agent and an anti-inflamma- tory substance. This report further explores the heterogeneity of this syn- drome by discussing the causes, clinical signs, diagnostic procedures and treat- ments that may be considered in horses with headshaking.

MATERIALS AND METHODS The clinical records of 2 horses admitted between October 2007 and June 2008 to the Equine Clinic of the Onderstepoort Veterinary Academic Hospital (OVAH) that had a primary complaint of head- shaking are reviewed. The history, signal- ment, clinical signs, diagnostic methods, diagnosis and treatment were recorded in each case.

CASE HISTORY Case 1 A 12-year-old, retired Thoroughbred aDepartment of Companion Animal Clinical Studies, Equine Internal Medicine, Faculty of Veterinary Science, Private Bag X04, Onderstepoort, 0110 South Africa. Fig. 1: Lateral view of the occipital region of a 12-year-old Thoroughbred racehorse, show- *Author for correspondence. ing a 22 × 15 mm mushroom-shaped trabeculated mineral opacity located caudal to the E-mail: [email protected] nuchal crest (arrow) anda6mmopacity located cranial to the 1st larger opacity (arrow- Received: March 2009. Accepted: May 2009. head) (Horse 1).

0038-2809 Jl S.Afr.vet.Ass. (2009) 80(2): 111–113 111 phenylbutazone (Phenylbutazone BP, Kyron Laboratories Pty Ltd) (2.2 mg/kg, q12h, PO), dexamethazone (Kortico, Bayer Ltd.) (0.1 mg/kg, q24h, PO) and trimethoprim-sulfamethoxazole (Purbac®, Aspen Pharmacare) (25 mg/kg, q12h, PO) to reduce swelling caused by the suspected trauma to the poll. Local infiltration con- sisting of 45 mg methylprednisolone acetate (DepoMedrol™, Pfizer), 100 mg lignocaine hydrochloride (Lignocaine Injection 2 %, Bayer Ltd.) and Sarapin® (High Chemical Company) was adminis- tered in the nuchal ligament in the region of the nuchal fragment. No further head- shaking episodes occurred following treatment and the gelding was discharged from the clinic. Follow-up consultation 12 weeks after discharge indicated that no headshaking behaviour had been noticed.

Case 2 Fig. 2: Lateral oblique radiographic view of the occipital region of a 5-year-old Thorough- A 5-year-old, retired Thoroughbred race- bred racehorse, showing mineral opacities ranging from 5 to 10 mm (arrow) adjacent to the horse gelding developed signs of head- nuchal crest external occipital protruberance (Horse 2). shaking at rest and during exercise of 6-month duration. Clinical symptoms nuchal ligament in the region of the bony tion on the occiput2. This may be seen as included lifting of the upper lip, pawing fragment. After performing the infiltra- an incidental finding, but affected horses excessively and resting his head on the tion, the gelding was lunged and no head- tend to resist the reins, find difficulty in ground. Physical examination revealed shaking behaviour was noticed. Follow- flexion at the poll and may rear or shake hypertrophy of the ventral neck muscles. up consultation 1 year after discharge the head2,4. A radiograph (Fig. 2) of the occipital region indicated that the gelding’s headshaking Horses with insertional desmitis of the showed mineral opacities ranging from 5 behaviour had decreased by 90 %. nuchal ligament or injury to the tendon to 10 mm adjacent to the nuchal crest of insertion of semispinalis may have a external occipital protruberance which DISCUSSION tendency to shake their heads4. These appeared irregular and was suspected to In a retrospective study of 100 horses injuries usually occur due to trauma to be the corresponding fracture bed. These with headshaking, a specific aetiology the region or an excessive amount of mineral opacities had a rounded appear- could not be identified in 90 % of the cases lunging exercise while restricted with side ance and were considered to be due to and in only 2 horses could it be shown or draw reins4. In a report of insertional trauma to the poll region which occurred that correction of the disorder led to desmopathy of the nuchal ligament, several months previously. elimination of clinical signs6. Several 12 horses presented with various clinical Ultrasonographic examination of the underlying diseases can present with signs such as reluctance to bend the head, nuchal ligament was performed as de- headshaking signs, but the majority of stiffness of the neck, excessive head turn- scribed above. An 11 mm hyperechoic cases are idiopathic7,8,17,18. Irritation by ing and headshaking when exercised1. line could be seen casting an acoustic insects, dental disease, guttural pouch Diagnostic procedures performed on the shadow 10 mm to the right of the midline mycosis and empyema, otitis media and 12 horses indicated exostosis of the and 11 mm caudoventral to the nuchal interna, cranial nerve disorders, ocular protuberantia occipitalis, calcification of crest. Additional smaller concave hyper- disease, subepiglottal cyst, premaxillary the ligamentum nuchae or insertion echoic lines up to 5 mm on the right and bone cyst, ethmoid haematoma, fracture desmopathy1. 3 mm on the left of the midline were of the frontal bone, maxillary osteoma, As found in this report, horses with observed. The nuchal ligament on the protozoal myeloencephalitis and Trom- headshaking commonly show uncontrol- right lost its homogenous appearance bicula autumnalis larval infestation are all lable shaking of the head in a vertical, hor- and the ligament fibres appeared to be considered possible causes5,6,9,14,16,20. izontal or rotary direction without any hypoechoic with associated loss of fibre Nuchal crest avulsion fractures with apparent physical stimulus7,18. Other alignment. The right nuchal ligament corresponding nuchal ligament desmitis signs include nose rubbing, striking at the measured 1.9 cm2 vs 0.85 cm2 on the left. was the most significant finding in the 2 nose with the forelegs, head pressing and Following interpretation of diagnostic cases in this report. Furthermore, the head- active avoidance of light, warmth or wind imaging results, an avulsion fragment of shaking behaviour decreased in both on the face. Worsening of clinical signs with the nuchal crest, with an associated after the nuchal ligament was infiltrated exposure to light are common features of nuchal desmitis was the most significant with local anaesthetic and corticosteroid. photic headshaking7,8,14 and seasonality is finding. Serum biochemistry revealed Various published reports on equines demonstrated in half to three quarters of hyperfibrinogenaemia (5 g/ ). describe cervical injuries and bony horses which developed clinical signs of Local infiltration consisting of 18 mg changes to the skull and spine which may headshaking in the spring and early triamcinolone acetonide (Vetalog®, Fort cause clinical signs of headshaking6. New summer that ceased in late summer or au- Dodge) and 150 mg ropivacaine hydro- bone formation may occur in the region of tumn7,18. In some cases horses only chloride (Naropin®, AstraZeneca Phar- insertion of the nuchal ligament as well as showed headshaking when exercised7 maceuticals) was administered into the dorsal and ventral to the site of the inser- while others only showed it at rest14,18.

112 0038-2809 Tydskr.S.Afr.vet.Ver. (2009) 80(2): 111–113 Horses with headshaking at rest can be control, chiropractic manipulation, mela- Sottrum, Germany, 22–24 February 2002: regarded as having a particularly severe tonin administration and acupuncture 11–12 form of the disorder as noticed in both also had limited success7. can be 2. Butler J A, Colles C M, Dyson S J, Kold S E, Poulos P W 2000 The head. Clinical Radiol- cases reviewed in this report. managed medically with variable success, ogy of the Horse (2nd edn). Blackwell Science A thorough appraisal of the case history using topical and systemic treatment Limited, London: 327–402 and the observation of the type of head- including corticosteroids, , 3. Cook W R 1980 Headshaking in horses shaking may give an indication of the sodium cromoglycate, anticholinergics or Part 3: Diagnostic tests. Equine Practice 2: underlying aetiology11,14. Intolerance of sympathomimetics13. 31–40 4. Dyson S J 2003 The cervical spine and soft the bit or problems with the tack are Desmopathy of the nuchal ligament tissue of the neck. In Dyson S J, Ross M W frequently blamed as a cause of head- causing headshaking may be treated with (eds) Diagnosis and management of lameness shaking and should be eliminated before repeated infiltration of corticosteroids and in the horse (1st edn). Saunders, Missouri: further diagnostic procedures are per- local anaesthetic solution and modification 522–531 formed. Typically performed diagnostics of the training programme. The combina- 5. Kold S E, Østblom L C, Philipsen H P 1982 Headshaking caused by a maxillary osteoma may include radiography of the head and tion of drugs used to infiltrate the nuchal in a horse. Equine Veterinary Journal 14: neck including specific views of the ligament may differ due to availability, 167–169 paranasal sinuses and pharyngeal region. cost and previous experience. In this re- 6. Lane J G, Mair T S 1987 Observations on As changes to the protuberantia ossis port, an anaesthetic agent was used to headshaking in the horse. Equine Veterinary occipitalis may be an incidental finding provide local anaesthesia and for acute Journal 19: 331–336 7. Madigan J E, Bell S A 2001 Owner survey and not exclusively the cause of head- pain management in both horses. Sarapin of headshaking in horses. Journal of the shaking behaviour, ultrasonography of (a pitcher plant extract) is thought to American Veterinary Medical Association 219: the nuchal ligament or insertion of the affect nerves involved in pain sensation 334–337 semispinalis tendon is indicated to deter- while corticosteroids may be indicated in 8. Madigan J E, Kortz G, Murphy C, Rodger L mine the extent of desmopathy. Other inflammatory conditions. 1995 Photic headshaking in the horse: 7 cases. Equine Veterinary Journal 27: 306–311 diagnostics include nasopharyngeal en- The use of acupuncture or magnetic 9. Mair T S 1994 Headshaking associated with doscopy including guttural pouches field therapy, ultrasound or shock wave Trombicula autumnalis larval infestation in and the trachea up to the level of the therapy may help some horses4,12. A study two horses. Equine Veterinary Journal 26: carina, percussion of the paranasal sinuses, exploring the success of extracorporal 244–245 tracheal lavage cytology, nasal lavage, shock wave therapy included 12 horses 10. Mair T S 1999 Assessment of bilateral infra-orbital nerve blockage and bilateral skin testing for atopy, pinch mucosal presenting with various clinical signs infra-orbital neurectomy in the investiga- biopsies for histopathological examination such as headshaking and stiffness of the tion and treatment of idiopathic head- for evidence of allergic or inflammatory neck1. These signs were attributable to shaking. Equine Veterinary Journal 31: disease, aural endoscopy, otoscopy, dental changes of the protuberantia ossis 262–264 examination, neurological examination, occipitalis or the ligamentum nuchae as 11. Mair T,Lane G 1990 Headshaking in horses. In Practice 12: 183–186 local infiltration of local anaesthetic solu- indicated by radiographic imaging. The 12. McClure S, Weinberger T 2003 Extra- tion of the trigeminal nerve, complete shock wave treatment showed positive corporeal shock wave therapy: clinical blood count, serum chemistry profile and results as demonstrated by the fact that applications and regulation. Clinical virus isolation for equine herpes virus 1 84 % of the horses showed improvement Techniques in Equine Practice 2: 358–367 and 43,8,11,13,17,18. after 3 treatments with a treatment inter- 13. McGorum B C, Dixon P M 1990 Vasomotor rhinitis with headshaking in a pony. Equine Depending on the cause of the head- val of 4–18 days. The extracorporal shock Veterinary Journal 22: 220–222 shaking, therapy differs substantially and wave therapy is furthermore a non-inva- 14. Mills D S, Cook S, Taylor K, Jones B 2002 is often unrewarding especially when a sive method, causes no additional trauma Analysis of the variations in clinical signs specific aetiology could not be identified. to the area treated and has favourable shown by 254 cases of equine headshaking. Idiopathic headshaking may be treated cosmetic results1. Veterinary Record 150: 236–240 using and In conclusion, a specific aetiology in 15. Mills D S, Taylor K 2003 Field study of the 18 efficacy of three types of nose net for the with a reported success rate of >80% , horses with headshaking is seldom treatment of headshaking in horses. Veteri- cyproheptadine alone with a reported confirmed and even if an abnormality is nary Record 152: 41–44 success rate of >70%7,8 tracheostomy, detected, its significance may be uncer- 16. Moore L A, Johnson P J, Messer N T, Kline perineural anaesthesia/neurectomy of tain. In this report, avulsion fractures of K L, Crump L M, Knibb J R 1997 Manage- ment of headshaking in three horses by the posterior ethmoid branches of the the nuchal crest with associated nuchal treatment for protozoal myeloencephalitis. trigeminal nerve, nasal cavity flushing, desmitis was suspected to be the pri- Veterinary Record 141: 264–267 contact lenses, and occlusive nasal mary cause of the headshaking in both 17. Newton S A 2005 Idiopathic headshaking masks15,18. Bilateral infraorbital analgesia Thoroughbred racehorses and respon- in horses. Equine Veterinary Education 17: has demonstrated variable success in ded favourably to conservative therapy. 108–118 decreasing the signs of headshaking18 and 18. Newton S A, Knottenbelt D C, Eldridge P R 2000 Headshaking in horses: possible is associated with nasal irritation and ACKNOWLEDGEMENTS aetiopathogenesis suggested by the results 10 neuroma formation . Caudal compres- The authors would like to thank Drs of diagnostic tests and several treatment sion19 of the infraorbital nerve has also Edward Evans and David Evezard for the regimes used in 20 cases. Equine Veterinary been described in the treatment of idio- referral of these interesting cases to the Journal 32: 208–216 pathic headshaking and limits input from Onderstepoort Veterinary Animal Hospi- 19. Roberts V L H, McKane S A, Williams A, Knottenbelt D C 2009 Caudal compression the trigeminal nerve at a more caudal tal, University of Pretoria, South Africa. of the infraorbital nerve: a novel surgical 10 location than infraorbital neurectomy . technique for treatment of idiopathic head- The treatment of photic headshaking REFERENCES shaking and assessment of its efficacy in 24 with antihistamines, corticosteroids, non- 1. Brems R, Weiss D 2002 Extracorporal shock horses. Equine Veterinary Journal 41: 165–170 wave therapy at the insertion desmopathy 20. Stephenson R 2005 An unusual case of steriodal anti-inflammatory agents and of the nuchal ligament in horses. Sympo- headshaking caused by a premaxillary hyposensitivity therapy has been unrewar- sium of Extracorporal Shock Wave Users in bone cyst. Equine Veterinary Education 17: ding8. Antimicrobials, external parasite Veterinary Medicine, Pferdeklinik Barkhof, 102–107

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