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E1784. Craniocervical Instability: Are We Missing the Diagnosis?
Authors
  1. Lynn Gufeld; Virginia Commonwealth University
  2. Armaghan Faghihimehr; Virginia Commonwealth University
  3. Mohammad Gharavi; Virginia Commonwealth University
  4. Peter Haar; Virginia Commonwealth University
  5. Mauricio Jimenez; Virginia Commonwealth University
  6. Josephina Vossen; Virginia Commonwealth University
Background
• Craniocervical ligamentous instability has been implicated as an etiology for persistent symptoms and pathology that may be missed on static imaging and standard measurement parameters. • Instability is defined as the inability to maintain the normal positioning of the vertebrae under load without damage or irritation to the spinal cord, brain stem or nerve roots. Severe pain due to spinal structural failure is an indirect marker of instability. • Current criteria for upper cervical instability is controversial, forcing a need for a reliable and standardized diagnostic system. • There is scant data in the neurosurgical and orthopedic literature regarding accepted imaging protocols and measurement parameters to identify ligamentous instability of the cervical spine barring that seen in acute trauma. • The scarcity of data is a problem for the provider caring for these patients and can result in missed and delayed diagnosis for patients living with disabling pain and profound functional deficits. • Upright / or multipositional imaging which will be referred to as “functional imaging” should be considered for patients with persistent and disabling symptoms where there is suspicion of instability but none seen on standard imaging. • An understanding of the unique measurements and of functional imaging of the upper cervical spine and their pathological significance is essential for both the radiologist and specialist provider.

Educational Goals / Teaching Points
• Describe normal anatomy and biomechanics of the cervical spine with attention to occiput - C1 and C1-C2 • Describe pathologic conditions as a result of ligamentous laxity that may be missed on standard static imaging • Describe and illustrate measurement parameters for functional imaging • Correlate pathologic symptoms with abnormal biomechanics and their specific imaging features • Describe conservative and surgical management of clinically significant cervical instability Target audience: • Radiology residents, general radiologists, MSK and neuroradiologists

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
We will review: - Anatomy of Craniocervical Junction; including Craniocervical junction (CCJ), Atlantooccipital joint (AOJ), Atlantoaxial joint (AAJ) and Craniocervical Ligaments - Imaging findings indicative of instability on static imaging - Imaging findings indicative of instability on functional imaging of the AOJ - Imaging findings indicative of instability on functional imaging of the AAJ

Conclusion
• Upright and multipositional imaging is important for the diagnosis of craniocervical ligamentous instability. • The diagnosis can be delayed / or missed unless the appropriate imaging is acquired and accurately interpreted. • Patients with a history of chronic whiplash injury and those with congenital and degenerative connective tissue disease, especially those with hypermobility generally require greater imaging and workup than the standard supine static imaging protocols. • Understanding and applying the measurements to evaluate the craniocervical junction with functional imaging can allow for a more thorough and expedient diagnosis of craniocervical ligamentous instability.