A 35-year-old Thai woman with Juvenile Idiopathic Arthritis (JIA), RF positive polyarthritis subtype, presented with chronic neck pain radiating to occiput for 6 mo. Plain film and CT scan of neck were evaluated. 

Question: 

What is the provisional diagnosis? 

โดย น.ท.หญิง อินทิรา  อุไรเลิศ อาจารย์หน่วยอายุรศาสตร์โรคข้อและรูมาติสซั่ม กองอายุรกรรม โรงพยาบาลภูมิพลอดุลยเดช พอ.

ANSWERs

The provisional diagnosis:  C1-2 subluxation (Basilar invagination) 

• Normally, dens of C2 is attached to the anterior facet of C1.
• Atlanto-axial (C1-2) subluxation is when there is dislocation or subluxation of anterior facet of C1 and dens of C2, due to long-standing and usually active disease of JIA and rheumatoid arthritis (RA). 
• Types of C1-2 subluxation:  anteroposterior, rotatory, vertical, and lateral subluxation
• A study was done in 35 patients with JIA in Charles Nicolle Hospital, Tunisia. Mean duration of JIA was 27 years and 43.5% of the patients were RF positive polyarthritis subtype. The result revealed that cervical spine involvement occurred on average at 7 years after JIA onset. MRI of C-spine was performed in 9 patients and showed that 4 of them had basilar invagination. 
• Basilar Invagination is when odontoid process abnormally protudes into the foramen magnum.
  • Diagnosis:  apex of the odontoid process of C2 at more than 4.5 mm above the McGregor’s line
  • May induce cervicomedullary compression => which can lead to devastating neurologic manifestations (neck pain, weakness, numbness, ataxia and quadriparesis) 

References: 

Bouden S, Ben Chekaya N, Ben Tekaya A, et al. CERVICAL SPINE INVOLVEMENT IN PATIENTS WITH JUVENILE IDIOPATHIC ARTHRITIS. Annals of the Rheumatic Diseases 2021;80:1396.

Prof. Dr. Pedro Fernandes. Review on Basilar Invagination of Rheumatoid Arthritis. DEPARTMENT OF ORTHOPAEDIC SURGERY, University of Lisbon, Protugal. July 2022

McGregor, M. (1948). The significance of certain measurements of the skull in the diagnosis of basilar impression. The British journal of radiology, 171–181.

Sharif, K. S. (2018). Rheumatoid arthritis in review: Clinical, anatomical, cellular and molecular points of view. Clinical anatomy, 216–223.

Smith, J. S., Shaffrey, C. I., Abel, M. F., & Menezes, A. H. (2010). Basilar invagination. Neurosurgery, 39-47.

Mostafa Elfeky. Atlanto-axial subluxation. www.radiopaedia.org. Jul 2023.

โดย น.ท.หญิง อินทิรา  อุไรเลิศ อาจารย์หน่วยอายุรศาสตร์โรคข้อและรูมาติสซั่ม กองอายุรกรรม โรงพยาบาลภูมิพลอดุลยเดช พอ.