Changes

There are two causes for the instability – trauma and developmental malformations.   

There are two causes for the instability – trauma and developmental malformations.   

:'''Traumatic instability''' occurs after forceful flexion of the head, causing either fracture of the dens or another part of the axis, and/or tearing of the fibrous attachments. This can occur in any breed, at any age.

:'''Traumatic instability''' occurs after forceful flexion of the head, causing either fracture of the dens or another part of the axis, and/or tearing of the fibrous attachments. This can occur in any breed, at any age.

:'''Developmental malformations''' can predispose the instability to occur with vary small amounts of trauma. Abnormalities include: a '''missing or malformed dens''', lack of normal attachment between the two vertebrae. This occurs most frequently in '''small breed dogs''' such as the Yorkshire Terrier, Chihuahua, Poodle, Pomeranian and Pekinese during their '''first year of life'''.  

:'''Developmental malformations''' can predispose the instability to occur with very small amounts of trauma. Abnormalities include: a '''missing or malformed dens''', lack of normal attachment between the two vertebrae. This occurs most frequently in '''small breed dogs''' such as the Yorkshire Terrier, Chihuahua, Poodle, Pomeranian and Pekinese during their '''first year of life'''.  

==Clinical Signs==

==Clinical Signs==

Problems include: '''continued instability''', deterioration of clinical signs, bandage sores from the neck brace.

Problems include: '''continued instability''', deterioration of clinical signs, bandage sores from the neck brace.

'''Surgical management is the treatment of choice''' due to the possibility of recurrence and further spinal cord damage with conservative management.

'''Surgical management is the treatment of choice''' due to the possibility of recurrence and further spinal cord damage with conservative management. Goals of surgery are to relieve pressure on the spinal cord and stabilise the joint permanently. If the dens is fractured or malformed, it may have to be removed at surgery.

 

Goals of surgery are to relieve pressure on the spinal cord and stabilise the joint permanently.  

 

If the dens is fractured or malformed, it may have to be removed at surgery.

Dorsal and ventral approaches exist, but the '''ventral approach''' is preferred as it enables arthrodesis of the atlantoaxial joint to be performed. A cancellous bone graft is placed in the joint and '''pins or screws are placed across the joints'''.  

Dorsal and ventral approaches exist, but the '''ventral approach''' is preferred as it enables arthrodesis of the atlantoaxial joint to be performed. A cancellous bone graft is placed in the joint and '''pins or screws are placed across the joints'''.  

Greater success is seen in younger dogs and dogs with more acute problems.

Greater success is seen in younger dogs and dogs with more acute problems.

==References==

==References==

Lister, S. (2009) '''Atlantoaxial instability''' ''ACVS Publication''

Lister, S. (2009) '''Atlantoaxial instability''' ''ACVS Publication''

[[Category:To Do - Helen]]

 

[[Category:To Do - Review]]

[[Category:Neurological Diseases - Dog]]

[[Category:Expert Review - Small Animal]]

[[Category:Joints - Degenerative Pathology]]

[[Category:Joints - Degenerative Pathology]]