Answer for CoW 18 Feb 2018
Craniovertebral junction anomaly
Findings
Tonsillar herniation noted below the level of foramen magnum • Bilateral lateral and third ventricles grossly dilated. • Os odontoideum • Atlanto-axial subluxation causing severe spinal canal narrowing at level of dens • Cervical cord compression,cord thinning and intramedullary hyperintensity at C1 -C2 levels- myelomalacia
Discussion
Craniovertebral junction (CVJ) is a collective term that refers to the occiput (posterior skull base), atlas, axis, and supporting ligaments. It encloses the soft tissue structures of the cervicomedullary junction medulla, spinal cord, and lower cranial nerves). Signs and Symptoms of CVJ Abnormalities • Motor myelopathy - quadriparesis, tniparesis, paraparesis, hemiparesis, or monoparesis • Sensory abnormalities- Posterior column dysfunction,Hypalgesia ,bladder dysfunctionract dysfunction)Bladder dysfunction ( • Brain stem dysfunction- nystagmus,ataxia • Lower cranial nerve dysfunction- difficulty in hearing, dysphagia, tongue atrophy • Vascular compromise-Syncope,Vertigo MALFORMATION OF AXIS AND ODONTOID PROCESS • Atlanto-axial fusion • Persistent ossiculum terminale • Os odontoideum • Odontoid dysplasia OS ODONTOIDEUM The term “os odontoideum,” first introduced by Giacomini in 1886, refers to an independent osseous structure lying cephalad to the axis body in the location of the odontoid process The anterior arch of the atlas may appear rounded and hypertrophic, In the presence of an os odontoideum, • the axis body has a well-corticated convex upper margin, and the anterior atlas arch appears rounded and hypertrophic. (partially lies above the axis body) • Lateral plain radiograph reveals absence of the odontoid process • the Wackenheim clivus baseline falls tangent to the anterior aspect of the os. In contrast, type 2 odontoid fracture is typically associated • flattened, sharp, uncorticated margin to the upper axis body and • a normal, halfmoon-shaped appearance to the anterior atlas arch , Because the gap between the os odontoideum and the axis body usually extends above the level of the superior articular facet of the axis, cruciate ligament incompetence and atlantoaxial instability are common When present, instability may lead to substantial narrowing of the spinal canal and cord compression at the level of C- 1 . The degree of instability must be assessed by comparison of flexion and extension studies with plain radiography, polytomography, or MR imaging.
References Craniovertebral Junction: Normal Anatomy, Craniometry,and Congenital anomalies Wendy R. K Smoker ( RadioGraphics 1994)
Findings
Tonsillar herniation noted below the level of foramen magnum • Bilateral lateral and third ventricles grossly dilated. • Os odontoideum • Atlanto-axial subluxation causing severe spinal canal narrowing at level of dens • Cervical cord compression,cord thinning and intramedullary hyperintensity at C1 -C2 levels- myelomalacia
Discussion
Craniovertebral junction (CVJ) is a collective term that refers to the occiput (posterior skull base), atlas, axis, and supporting ligaments. It encloses the soft tissue structures of the cervicomedullary junction medulla, spinal cord, and lower cranial nerves). Signs and Symptoms of CVJ Abnormalities • Motor myelopathy - quadriparesis, tniparesis, paraparesis, hemiparesis, or monoparesis • Sensory abnormalities- Posterior column dysfunction,Hypalgesia ,bladder dysfunctionract dysfunction)Bladder dysfunction ( • Brain stem dysfunction- nystagmus,ataxia • Lower cranial nerve dysfunction- difficulty in hearing, dysphagia, tongue atrophy • Vascular compromise-Syncope,Vertigo MALFORMATION OF AXIS AND ODONTOID PROCESS • Atlanto-axial fusion • Persistent ossiculum terminale • Os odontoideum • Odontoid dysplasia OS ODONTOIDEUM The term “os odontoideum,” first introduced by Giacomini in 1886, refers to an independent osseous structure lying cephalad to the axis body in the location of the odontoid process The anterior arch of the atlas may appear rounded and hypertrophic, In the presence of an os odontoideum, • the axis body has a well-corticated convex upper margin, and the anterior atlas arch appears rounded and hypertrophic. (partially lies above the axis body) • Lateral plain radiograph reveals absence of the odontoid process • the Wackenheim clivus baseline falls tangent to the anterior aspect of the os. In contrast, type 2 odontoid fracture is typically associated • flattened, sharp, uncorticated margin to the upper axis body and • a normal, halfmoon-shaped appearance to the anterior atlas arch , Because the gap between the os odontoideum and the axis body usually extends above the level of the superior articular facet of the axis, cruciate ligament incompetence and atlantoaxial instability are common When present, instability may lead to substantial narrowing of the spinal canal and cord compression at the level of C- 1 . The degree of instability must be assessed by comparison of flexion and extension studies with plain radiography, polytomography, or MR imaging.
References Craniovertebral Junction: Normal Anatomy, Craniometry,and Congenital anomalies Wendy R. K Smoker ( RadioGraphics 1994)
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!