Complicação cirúrgica e re-intervenção em cão com subluxação atlantoaxial tratada por estabilização cirúrgica ventral
Authors: Peres Cabreira Adan , Dias da Silva Murilo Henrique , Bregalioli Thales , Covino Diamante Gabriel Antonio 
Published: December 2024

Background: The atlantoaxial subluxation condition presents neurological alterations due to joint instability, vertebral misalignment, and subsequent compression and injury to the spinal cord parenchyma. It occurs more frequently in young dogs of toy breeds, but it can also happen in large breed dogs and cats. The present study aims to report a case of atlantoaxial instability in a canine, a 7-year-old female Yorkshire Terrier, through surgical treatment using a modified ventral (parasagittal) approach.
Case: A 7-year-old, 4.5 kg female Yorkshire Terrier, spayed, was brought to OrthoSupport Pet with a complaint of vocalization suggestive of pain when jumping off the sofa. During the clinical/neurological examination, the animal exhibited signs consistent with a cervical syndrome. The diagnosis was made through a computed tomography scan, which revealed dorsal displacement of the axis in relation to the atlas. As a result, surgical treatment was initiated using the modified ventral stabilization technique (parasagittal) with screws and polymethylmethacrylate. However, the patient experienced a recurrence of the neurological symptoms seven days after the surgical procedure, attributed to implant failure. A second surgical intervention was performed, resulting in therapeutic success.
Discussion: The patient exhibited non-ambulatory tetraparesis after jumping off the sofa. The animal's caregiver reported that similar episodes had occurred in the past during the pet's life. It's worth noting that although most animals display clinical signs before the age of 6 months, older patients can also develop atlantoaxial subluxation due to joint instability, as described in this case report. Animals affected by atlantoaxial subluxation can manifest a range of symptoms, from cervical pain to tetraplegia, and, in severe cases, even respiratory failure leading to death. The presentation of signs after a jump, coupled with the subsequent improvement in clinical signs, suggests a distinctive feature where there is intermittent misalignment and realignment of the atlantoaxial joint, resulting in intermittent spinal cord compression. The parasagittal approach is a modification of the ventral approach that requires less dissection, reduces tissue recovery time, involves less manipulation, and minimizes the displacement of structures like the trachea. Initially, ventral stabilization with screws and polymethylmethacrylate was performed as per the routine, but the implant failed. Subsequently, a second intervention was conducted, involving the addition of transarticular pins and a screw at C3, resulting in a successful therapeutic outcome. The parasagittal approach offers advantages as an alternative to the conventional ventral approach. Although the presentation of the disease in animals over two years of age is relatively uncommon, it should still be considered as a differential diagnosis when the clinical signs are compatible.