Histology of the craniocervical junction in chronic rheumatoid arthritis: a clinicopathologic analysis of 33 operative cases.
METHODS
A histologic review of surgical specimens with clinical and radiographic correlations.


OBJECTIVE
To analyze the histopathology at the craniocervical junction in chronic rheumatoid arthritis (RA).


BACKGROUND
It has been assumed that the tissue identified on radiography at the craniocervical junction causing anterior spinal cord compression in patients with chronic RA is hypertrophic rheumatoid synovium. To date, no study has positively identified the histology of this tissue.


METHODS
Transoral resection of the dens and spinal cord decompression were performed in 33 myelopathic rheumatoid patients with craniocervical instability. The resected specimens were examined histologically.


RESULTS
Two unique histologic patterns were identified. Type I synovium has a recognizable synovial structure but without a hyperplastic synovial layer, significant inflammatory cell population, or lymphocytic infiltration typical of early active rheumatoid synovium. Type II synovium is a bland, fibrous, hypercellular tissue that is hypovascular, with little synovium and few inflammatory cells. Clinically and radiologically the two groups are distinct. Patients with Type II synovium are older ( = 0.008) and present with more advanced neurologic involvement caused by spinal cord compression ( = 0.0001). The mean difference in the spinal cord area between the two groups was 20.6 mm (95% confidence interval, 10.0-31.2 mm; = 0.004).


CONCLUSIONS
The histologic specimens suggest that ligamentous destruction is followed by replacement of the rheumatoid synovium with fibrous tissue, whereas the osseous structures reveal severe destruction secondary to mechanical instability, rather than to an acute inflammatory process. Early, preemptive surgical intervention may prevent the development of spinal cord injury caused by instability.
O'Brien
Michael F
MF
Woodridge Orthopedic Clinic and Spine Center, Wheat Ridge, Colorado, USA.
Casey
Adrian T H
AT
Crockard
Alan
A
Pringle
Jean
J
Stevens
John M
JM
D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications / Q000473:pathology* / Q000601:surgery; D001268:Atlanto-Axial Joint / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D002574:Cervical Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D002908:Chronic Disease; D015331:Cohort Studies; D019299:Decompression, Surgical; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013117:Spinal Cord Compression / Q000209:etiology / Q000473:pathology / Q000601:surgery; D000074402:Synovectomy; D013583:Synovial Membrane / Q000473:pathology*