Craniocervical junction abnormalities with atlantoaxial subluxation caused by ventral subluxation of C2 in a dog

Itoh, Harumichi; Itamoto, Kazuhito; Eto, Shotaro; Haraguchi, Tomoya; Nishikawa, Shimpei; Tani, Kenji; Itoh, Yoshiki; Hiyama, Masato; Iseri, Toshie; Nakaichi, Munekazu; Taura, Yasuho

doi:10.4314/ovj.v7i1.10

Cited by 2 publications

(1 citation statement)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In both veterinary and human medicine, traumatic events are the primary cause of AOD, resulting in significant dynamic instability between the atlanto-occipital (AO) joint. However, in humans, it can also emerge in conjunction with conditions such as rheumatoid arthritis, Down syndrome, congenital cervical vertebral fusion, and neoplasia [1,3,[8][9][10]. The paucity of reported cases is potentially due to the rapid progression towards mortality and diagnostic challenges within the veterinary field [11,12].…”

Section: Introductionmentioning

confidence: 99%

C1 Facetectomy and Ventral Fixation of Occipitoatlantoaxial Complex for Concurrent Congenital Atlanto-Occipital Dislocation and Atlantoaxial Instability in a Toy Poodle

Kim,

Jeong,

Jeon

et al. 2024

Animals

View full text Add to dashboard Cite

An 8-month-old, 3.4 kg, castrated male Toy Poodle was referred for progressive tetraparesis and respiratory disorder without a history of trauma. Repeated computed tomography (CT) and magnetic resonance imaging (MRI) with different positions of the neck revealed concurrent atlanto-occipital dislocation (AOD) and atlantoaxial instability (AAI) with spinal cord compression. This case was unique due to its congenital nature and the absence of trauma. The surgical treatment involved precise removal of the C1 vertebra’s ventral articular facet, which was compressing on the spinal cord, attributed to its fixed and malaligned position within the atlantooccipital joint. Following facetectomy, the stabilization of the occipital bone to the C2 vertebra was achieved by screws, wire, and polymethyl methacrylate. Two days after surgery, the dog recovered ambulation and showed gradual improvement in gait, despite mild residual ataxia. Postoperative CT and radiographs showed successful decompression of the spinal cord. The screw loosening was confirmed at 114 days, which was managed successfully by extracting the affected screws. Through the 21-month monitoring period, the dog showed a normal gait with a wide-based stance of the pelvic limbs when standing and experienced no pain. This case represents the first report of concurrent congenital AOD and AAI treated with a ventral surgical approach, contributing new insights to the understanding and management of such complex cranio-cervical junction disorders in veterinary neurosurgery.

show abstract

Section: Introductionmentioning

confidence: 99%

C1 Facetectomy and Ventral Fixation of Occipitoatlantoaxial Complex for Concurrent Congenital Atlanto-Occipital Dislocation and Atlantoaxial Instability in a Toy Poodle

Kim,

Jeong,

Jeon

et al. 2024

Animals

View full text Add to dashboard Cite

show abstract

Multiple Malformations of the Craniocervical Junction in German Spitz Adult Dog

Siqueira,

Machado,

Santos

et al. 2024

Acta Scientiae Vet.

View full text Add to dashboard Cite

Background: Craniocervical junction abnormalities (CJA) are described as complex congenital malformations affecting the caudal occipital region and 1st cervical vertebrae. These abnormalities often include Chiari malformations, atlanto-occipital overlapping, cervical canal stenosis, and atlantoaxial instability. There are few descriptions of these conditions in veterinary literature, despite their relevance. This report’s aim is to describe a case of complex craniocervical malformation in a dog, presenting the clinical findings, diagnostic methods, surgical treatment, and post-operative evolution, thus improving the understanding and management of such cases in veterinary practice. Case: A 4-year-old German Spitz dog, weighing 4.6 kg, was presented to a Veterinary Hospital in São Paulo State with a history of cervical hyperesthesia and non-ambulatory tetraparesis. Neurological examination revealed an absence of conscious proprioception in both thoracic and pelvic limbs, along with segmental hyperreflexia, pointing the neurolocalization of the lesion to the C1-C5 spinal segment. The dog's clinical evolution indicated further involvement of the brainstem, thalamic, and cerebellar regions. Cervical radiographs showed changes suggestive of craniocervical and vertebral malformations at C1-C2. Magnetic resonance imaging (MRI) further elucidated these findings, revealing a complex malformation causing significant compression of the medulla oblongata, atlanto-occipital overlapping, dysplasia/hypoplasia of the occipital bone, and mild cerebellar herniation, leading to partial obstruction of cerebrospinal fluid (CSF) flow. CSF cytology did not show significant abnormalities. Due to the unfavorable evolution of the patient, it was necessary to intervene surgically. The dog underwent foramen magnum decompression (FMD) with suboccipital craniectomy associated to cranioplasty using titanium mesh. Additionally, C1 laminoplasty and C1-C2 laminectomy were performed to maintain the stability of the atlanto-occipital joint and provide access to the dura mater. The dog presented a gradual and complete recovery of its motor function in the post-operative period, indicating a successful surgical treatment. Discussion: This case highlights the importance of advanced diagnostic imaging, such as MRI, in accurately identifying and assessing craniocervical junction abnormalities in dogs beyond what radiographs are able to identify. The successful surgical outcome obtained in this case shows the effectiveness of combining different surgical approaches for the management of such malformations. The foramen magnum decompression with cranioplasty, C1 laminoplasty, and C1-C2 laminectomy are great examples of fruitful combined techniques. Conservative therapies, such as pain management and the use of carbonic anhydrase inhibitors, may be satisfactory treatment options but could be insufficient for severe cases. Surgical intervention, as demonstrated, can significantly improve prognosis and quality of life by relieving compressive forces on the medulla oblongata and restoring normal CSF flow. The use of cranioplasty is particularly beneficial in reducing complications associated with scar tissue formation. This report adds valuable data to the limited veterinary literature on CJA, emphasizing the need for precise diagnosis and the advantages of the association of surgical approaches. This knowledge will ultimately improve treatment outcomes and the quality of life for animals with such abnormalities. Keywords: laminectomy, malformation, magnetic resonance, small animals, surgery.

show abstract

Craniocervical junction abnormalities with atlantoaxial subluxation caused by ventral subluxation of C2 in a dog

Cited by 2 publications

References 13 publications

C1 Facetectomy and Ventral Fixation of Occipitoatlantoaxial Complex for Concurrent Congenital Atlanto-Occipital Dislocation and Atlantoaxial Instability in a Toy Poodle

C1 Facetectomy and Ventral Fixation of Occipitoatlantoaxial Complex for Concurrent Congenital Atlanto-Occipital Dislocation and Atlantoaxial Instability in a Toy Poodle

Multiple Malformations of the Craniocervical Junction in German Spitz Adult Dog

Contact Info

Product

Resources

About