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148 Section III: Spinal Procedures

Postoperative Management 7 Shires PK. Atlantoaxial instability. In: Slatter D (ed.) Textbook of Small Animal
Immediate postoperative management is directly related to possible Surgery, 3rd edn. Philadelphia, PA: WB Saunders, 2003: 1173–1180.
complications associated with iatrogenic cervical myelopathic 8 Cerda‐Gonzalez S. Congenital diseases of the craniocervical junction in the dog.
Vet Clin North Am Small Anim Pract 2009;20:121–141.
injury or the soft tissue approach itself. Capnography or blood gas 9 Denny HR, Gibbs C, Waterman A. Atlanto‐axial subluxation in the dog: a review of
monitoring is recommended up until extubation to ensure the ani- thirty cases and an evaluation of treatment by lag screw fixation. J Small Anim Pract
mal can ventilate appropriately. As a neuropraxia associated with 1988;29:37–47.
the recurrent laryngeal nerve can occur, the author prefers to hold 10 Platt SR, Chambers JN, Cross A. A modified ventral fixation for surgical manage-
ment of atlantoaxial subluxation in 19 dogs. Vet Surg 2004;33:349–354.
food postoperatively for 12 hours. This is not always feasible as 11 Kent M, Eagleson JS, Neravanda D, Schatzberg SJ, Gruenenfelder FI, Platt SR.
these small patients may not be able to maintain normoglycemia. Intraaxial spinal cord hemorrhage secondary to atlantoaxial subluxation in a dog.
Because of the anatomical configuration of C1–C2 in young toy J Am Anim Hosp Assoc 2010;46:132–137.
breeds, any form of fixation is initially considered marginal. Regardless 12 Owen MC, Davis SH, Worth AJ. Imaging diagnosis: traumatic myelopathy in a dog
of whether a dorsal or ventral approach is used, the neck is supported with incomplete ossification of the dorsal lamina of the atlas. Vet Radiol Ultrasound
2008;49:570–572.
with a neck brace, and strict cage confinement should be enforced 13 Parry AT, Upjohn MM, Schlegl K, Kneissl S, Lamb CR. Computed tomography
until radiographic evidence of union (see Figure 15.5). When applied, variations in morphology of the canine atlas in dogs with and without atlantoaxial
the goal of external coaptation is to prevent ventroflexion and is less subluxation. Vet Radiol Ultrasound 2010;51:596–600.
concerned with rotation or dorso‐extensive movement. As such, the 14 Middleton G, Hillmann DJ, Trichel J, Bragulla HH, Gaschen L. Magnetic resonance
brace is often contoured to allow for such movements. imaging of the ligamentous structures of the occipitoatlantoaxial region in the dog.
Vet Radiol Ultrasound 2012;53:545–551.
15 Marino DJ, Loughin CA, Dewey CW et al. Morphometric features of the craniocer-
vical junction region in dogs with suspected Chiari‐like malformation determined
Surgical Prognosis by combined use of magnetic resonance imaging and computed tomography. Am J
Factors associated with a more favorable outcome following surgi- Vet Res 2012;73:105–111.
cal stabilization include dogs less than 2 years of age at onset of 16 Havig ME, Cornell KK, Hawthorne JC, McDonnell JJ, Selcer BA. Evaluation of
clinical signs, clinical signs for less than 10 months prior to the pro- nonsurgical treatment of atlantoaxial subluxation in dogs: 19 cases (1992–2001).
J Am Vet Med Assoc 2005;227:257–262.
cedure, a duration of clinical signs greater than 30 days, and an 17 Kishigami M. Application of an atlantoaxial retractor for atlantoaxial subluxation
ambulatory preoperative status [10,34]. in the cat and dog. J Am Anim Hosp Assoc 1984;20:413–419.
Though the procedure is often associated with high rates of success, 18 LeCouteur, RA, McKeown D, Johnson J, Eger CE. Stabilization of atlantoaxial sub-
neck pain persists in 10% of cases and clinical ataxia in 20% of luxation in the dog, using the nuchal ligament. J Am Vet Med Assoc 1980;177:
1011–1017.
cases. Should a second surgery be warranted, the literature suggests 19 Chambers JN, Betts CW, Oliver JE. The use of nonmetallic suture material for
that these cases are amenable to repeat procedures with a relatively stabilization of atlantoaxial subluxation. J Am Anim Hosp Assoc 1977;13:602–604.
high rate of success [34]. 20 van Ee RT, Pechman R, van Ee RM. Failure of the atlantoaxial tension band in two
dogs. J Am Anim Hosp Assoc 1989;25:707–712.
21 Pujol E, Bouvy B, Omaña M, Fortuny M, Riera L, Pujol P. Use of the Kishigami
Summary atlantoaxial tension band in eight toy breed dogs with atlantoaxial subluxation. Vet
Surg 2010;39:35–42.
Cases of AAS present the neurosurgeon with a unique challenge 22 Jeffery ND. Dorsal cross pinning of the atlantoaxial joint: new surgical technique
with regard to proper approach, adequate reduction, and durable for atlantoaxial subluxation. J Small Anim Pract 1996;37:26–29.
stabilization in small patients with delicate anatomy. Diagnostic 23 Piermattei DL, Johnson KA. An Atlas of Surgical Approaches to the Bones and Joints
imaging is essential in the planning of these procedures. As these of the Dog and Cat, 4th edn. Philadelphia, PA: Elsevier Health, 2004: 48–51.
cases present sporadically in clinical practice, acquiring adequate 24 Shores A, Tepper LC, A modified ventral approach to the atlantoaxial junction in
the dog. Vet Surg 2007;36:765–770.
experience to be proficient in the techniques may pose a challenge. 25 Forterre, F, Vizcaino‐Revés, N, Stahl C, Gendron K, Spreng D. An indirect reduc-
The current body of evidence would suggest that the ventral tion technique for ventral stabilization of atlantoaxial instability in miniature breed
approach with rigid stabilization by transarticular screws or multi- dogs. Vet Comp Orthop Traumatol 2012;25:332–336.
ple implants yields the most positive outcomes. 26 Pike FS, Kumar MS, Boudrieau RJ. Reduction and fixation of cranial cervical
fracture/luxations using screws and polymethylmethacrylate (PMMA) cement: a
distraction technique applied to the base of the skull in thirteen dogs. Vet Surg
2012;41:235–247.
Video clips to accompany this book can be found on 27 Schulz KS, Waldron DR, Fahie M. Application of ventral pins and polymethylmeth-
the companion website at: acrylate for the management of atlantoaxial instability: results in nine dogs. Vet
Surg 1997;26:317–325.
www.wiley.com/go/shores/neurosurgery 28 Sorjonen DC, Shires PK. Atlantoaxial instability: a ventral surgical technique for
decompression, fixation, and fusion. Vet Surg 1981;10:22–29.
29 Blass CE, Waldron DR, van Ee RT. Cervical stabilization in three dogs using
Steinmann pins and methylmethacrylate. J Am Anim Hosp Assoc 1988;24:61–68.
30 Renegar WR, Stoll SG. The use of methylmethacrylate bone cement in the repair of
References atlantoaxial subluxation stabilization failures: case report and discussion. J Am
1 Thomas WB, Sorjonen DC, Simpson ST. Surgical management of atlantoaxial sub- Anim Hosp Assoc 1979;15:313–318.
luxation in 23 dogs. Vet Surg 1991;20:409–412. 31 Sanders SG, Bagley RS, Silver GM, Moore M, Tucker RL. Outcomes and complica-
2 Seim III HB. Atlantoaxial instability. In: Fossum TW (ed.) Small Animal Surgery, tions associated with ventral screws, pins, and polymethylmethacrylate for atlanto-
2nd edn. St Louis, MO: Mosby, 2002: 1250–1255. axial instability in 12 dogs. J Am Anim Hosp Assoc 2004;40:204–210.
3 Rochat MC, Shores A. Fixation of an atlantoaxial subluxation by use of cannulated 32 Dickomeit M, Alves L, Pekarkova M et al. Use of a 1.5 mm butterfly locking plate for
screws. Vet Comp Orthop Traumatol 1999;12:43–46. stabilization of atlantoaxial pathology in three toy breed dogs. Vet Comp Orthop
4 Watson AG, Evans HE, de Lahunta A. Ossification of the atlas–axis complex in the Traumatol 2011;24:246–251.
dog. Anat Histol Embryol 1986;15:122–138. 33 Parker AJ, Park RD, Cusick PK. Abnormal odontoid proess. Vet Rec 1973;93:
5 Watson AG, de Lahunta A, Evans HE. Prenatal development of the composite occip- 559–561.
ito‐atlanto‐axial synovial joint cavity in the dog. Anat Rec 1986;216:423–433. 34 Beaver DP, Ellison GW, Lewis DD, Goring RL, Kubilis PS, Barchard C. Risk factors
6 Dyce KM, Sack WO, Wensing CJG. Textbook of Veterinary Anatomy, 4th edn. St affecting the outcome of surgery for atlantoaxial subluxation in dogs: 46 cases
Louis, MO: Saunders Elsevier, 2010: 409–410. (1978–1998). J Am Vet Med Assoc 2000;216:1104–1109.