Ultrasonographic Appearance of the Craniocervical Junction in Normal Brachycephalic Dogs and Dogs With Caudal Occipital (Chiari‐like) Malformation

Abstract

Ultrasonographic evaluation of the spine, especially of the spinal cord, has been rarely reported in dogs. The atlanto-occipital junction provides a small acoustic window through which examination of the craniocervical transition can be performed. Normal sonographic findings of this region in 10 normal brachycephalic dogs are presented and compared with sonographic findings from 25 Cavalier King Charles Spaniels with the caudal occipital malformation syndrome. Sonographic findings were compared with magnetic resonance imaging findings to determine the extent of cerebellar herniation and syringohydromyelia. Cerebellar displacement into the foramen magnum was clearly identified sonographically; however, syringohydromyelia was not discernable due to bone overlay.

Imaging Diagnosis-Cerebellar Displacement and Spina Bifida in a Calf

“…In this calf, using the craniocervical junction as an acoustic window, displacement of the cerebellum, caudal part of the brain stem and part of an occipital lobe into the cervical vertebral canal, and low‐grade hydrocephalus, was detected. The ultrasonographic appearances were similar to descriptions of caudal occipital malformations in dogs 3 . The brain malformation was also accompanied by congenital hydrocephalus, spina bifida with myelomeningocele, and incomplete closure of the dorsal vertebral laminae.…”

“…In puppies, the bregmatic fontanel can be used as an acoustic window to the brain up to approximately 1 month of age 1,2 . In adult dogs, the caudal structures of the brain and the cervical spinal cord can be partially visualized through the craniocervical junction when the neck is fully flexed 3 . At the level of the craniocervical junction, the cervical spinal cord is normally characterized, in transverse images, as an ellipsoid hypoechoic structure surrounded by a bright line representing the dura mater and arachnoid together, whereas the central canal appears as a central hyperechoic dot 3,4 .…”

“…In adult dogs, the caudal structures of the brain and the cervical spinal cord can be partially visualized through the craniocervical junction when the neck is fully flexed 3 . At the level of the craniocervical junction, the cervical spinal cord is normally characterized, in transverse images, as an ellipsoid hypoechoic structure surrounded by a bright line representing the dura mater and arachnoid together, whereas the central canal appears as a central hyperechoic dot 3,4 . In this calf, using the craniocervical junction as an acoustic window, displacement of the cerebellum, caudal part of the brain stem and part of an occipital lobe into the cervical vertebral canal, and low‐grade hydrocephalus, was detected.…”

Longitudinal Study of the Relationship among Craniocervical Morphology, Clinical Progression, and Syringomyelia in a Cohort of Cavalier King Charles Spaniels

“…C raniocervical junction anomalies frequently are diagnosed in small and toy breed dogs, particularly the Cavalier King Charles spaniel (CKCS) breed. [1][2][3][4][5][6] These can include Chiari-like malformations (CM), 3,[5][6][7] medullary elevation and herniation at the CCJ, 1,3,4,[8][9][10] dorsal atlantoaxial bands, 2,3,8,[11][12][13] atlantooccipital overlapping (AOO), 7,8,14 and secondary syringomyelia. 2,4,7,[15][16][17] Magnetic resonance imaging (MRI) of the brain and cervical spinal cord allows the diagnosis of each of these, whereas objective measurements are used to evaluate their severity (eg, cerebellar compression index, dorsal compression and medullary kinking indices, and obex position measurements).…”

Ultrasonographic identification of the dorsal atlantoaxial ligament in dogs

“…By contrast, ultrasonography is a fast, safe, and relatively inexpensive technique. Ultrasonography has been used to assess the craniocervical junction in animals with Chiari-like malformation and syngomyelia 5,16,17 and intracranial arachnoid cysts. 18 This modality has also been used to evaluate the musculoskeletal anatomy of the dorsal cervical spine.…”