Epidemiological and morphological characteristics of incomplete ossification of the dorsal neural arch of the atlas in dogs with atlantoaxial instability

Takahashi, Fumitaka; Hakozaki, Takaharu; Kouno, Shigenori; Suzuki, Shuji; Sato, Aya; Kanno, Nobuo; Harada, Yasuji; Yamaguchi, Shinya; Hara, Yasushi

doi:10.2460/ajvr.79.10.1079

Cited by 9 publications

(21 citation statements)

References 21 publications

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“…The conformation of the atlas of our patient could be consistent with incomplete ossification of the left ventral and the dorsal ossification center. These findings are in line with human literature regarding incomplete ossification of the atlas and in humans these paramedian sutures are recognized as being an anatomical variant 11–12 . This anomaly of the atlas secondary to incomplete ossification is encountered in combination with atlantoaxial instability or without any other abnormalities 13–15 .…”

Section: Discussionsupporting

confidence: 90%

Contrast‐enhanced CT findings in a dog with a wood foreign body in the vertebral canal

Bosma¹,

R²,

Visser

et al. 2021

Vet Radiology Ultrasound

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An 8‐year‐old Border collie was presented with progressive tetraparesis, 6 days after oropharyngeal trauma with a wooden stick. Contrast‐enhanced CT of the head and the cervical spine showed heterogeneous enhancement of the soft tissues surrounding the C1 through C3 region, with extension into the ventral vertebral canal at this level. Two separate, small, foreign bodies were visible; one of which was located within the vertebral canal. Surgical exploration confirmed the presence of wooden foreign bodies within the para‐vertebral soft tissues and within the vertebral canal. The dog was clinically normal 6 months postoperatively.

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Section: Discussionsupporting

confidence: 90%

Contrast‐enhanced CT findings in a dog with a wood foreign body in the vertebral canal

Bosma¹,

R²,

Visser

et al. 2021

Vet Radiology Ultrasound

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“…Only 30.7% of the affected cases in our study had observable dens abnormalities, which is less than previously reported . Incomplete ossification of the dorsal neural arch of the atlas as described by Takahashi et al, in additional to ligamentous failure, may help explain why most of our affected dogs had normal appearing dens according to radiographic evidence but suffered from AAI.…”

Section: Discussioncontrasting

confidence: 68%

Flexed radiographic angles for determination of atlantoaxial instability in dogs

et al. 2019

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Objective To determine a flexed position for radiographic diagnosis of atlantoaxial instability (AAI) and to identify radiographic measurement cutoffs to differentiate affected dogs from neurologically healthy toy breeds. Study design Retrospective case series and prospective case controls. Animals Thirty‐nine client‐owned toy breed dogs in which AAI had been diagnosed and 20 neurologically healthy client‐owned toy breed dogs. Methods Medical records from three institutions were retrospectively reviewed to identify dogs affected with AAI. Flexed lateral images were reviewed, and measurements were obtained by using anatomic landmarks. Radiography was performed with control dogs to obtain the same measurements. Results Flexed lateral radiographs of thirty dogs affected with AAI were found to be positioned at a mean of 51° flexion. When flexed lateral radiographs were evaluated with a cutoff value for atlas to axis angle (AAA) >10°, evaluation of all breeds represented revealed a 90% sensitivity and 90% specificity. When this cutoff was evaluated in Yorkshire terriers, Chihuahuas, and mixes of these breeds, the sensitivity was 92%, and the specificity was 92%. When the control sample was positioned at 51° ± 10°, only two of the dogs were within the AAA cutoff value of >10°. There was no difference between the measurements obtained by using the flexed lateral view (mean = 50.9°) and the exaggerated flexed lateral view (mean = 38.9°) in the control sample. Conclusion This study established objective measurements for the positioning and diagnosis of AAI on flexed lateral radiographs in toy breed dogs. Clinical significance Atlantoaxial instability can be objectively diagnosed in sedated or anesthetized toy breed dogs when applying 51° flexion to cervical radiographs.

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“…Odontoid process malformation (aplasia or hypoplasia) is the most frequently reported cause of AAI in dogs [ 4 ]. Other associated atlantoaxial congenital anomalies include incomplete ossification of the atlas (C1), separation of the dens from the axis (C2), and insufficient ligamentous support [ 5 , 6 , 7 , 8 ]. These malformations are more commonly encountered in young toy breed dogs [ 4 , 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a Novel Dorsal-Cemented Technique for Atlantoaxial Stabilisation in 12 Dogs

Tabanez

Gutierrez‐Quintana

Kaczmarska

et al. 2021

Life

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Dorsal atlantoaxial stabilisation (DAAS) has mostly been described to treat atlantoaxial instability using low stiffness constructs in dogs. The aim of this study was to assess the feasibility and surgical outcome of a rigid cemented DAAS technique using bone corridors that have not previously been reported. The medical records of 12 consecutive dogs treated with DAAS were retrospectively reviewed. The method involved bi-cortical screws placed in at least four of eight available bone corridors, embedded in polymethylmethacrylate. Screw placement was graded according to their position and the degree of the breach from the intended bone corridor. All DAAS procedures were completed successfully. A total of 72 atlantoaxial screws were placed: of those, 51 (70.8%) were optimal, 17 (23.6%) were suboptimal, and 4 (5.6%) were graded as hazardous (including 2 minor breaches of the vertebral canal). Surgical outcome was assessed via a review of client questionnaires, neurological examination, and postoperative CT images. The clinical outcome was considered good to excellent in all but one case that displayed episodic discomfort despite the appropriate atlantoaxial reduction. A single construct failure was identified despite a positive clinical outcome. This study suggests the proposed DAAS is a viable alternative to ventral techniques. Prospective studies are required to accurately compare the complication and success rate of both approaches.

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Epidemiological and morphological characteristics of incomplete ossification of the dorsal neural arch of the atlas in dogs with atlantoaxial instability

Cited by 9 publications

References 21 publications

Contrast‐enhanced CT findings in a dog with a wood foreign body in the vertebral canal

Contrast‐enhanced CT findings in a dog with a wood foreign body in the vertebral canal

Flexed radiographic angles for determination of atlantoaxial instability in dogs

Evaluation of a Novel Dorsal-Cemented Technique for Atlantoaxial Stabilisation in 12 Dogs

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