Case Reports

Indian Pediatrics 1999;36: 1163-1166

Atlanto-Axial Subluxation in JRA

From the Department of Pediatrics, Government Medical College and Hospital, Sector 32, Chandigarh, India.
Reprint requests: Dr. Sudeshna Mitra, Senior Lecturer, Department of Pediatrics, Government Medical College and Hospital, Sector-32, Chandigarh, India.
Manuscript Received: April 6, 1999;
Initial review completed: May 24, 1999;
Revision Accepted: July 7, 1999

The apophyseal joints of the cervical spine are affected at the onset of disease in only 2% of children with juvenile rheumatoid arthritis (JRA)(1). Subluxation may occur in any joint but this kind of instability at the atlanto-axial joint may lead to impingement of the odontoid on the cord and hence cervical compressive myelopathy. Both surgical(2) and conserva-tive(3) management have been tried for rheuma-toid atlanto-axial subluxation (AAS). Here we  report a child with JRA who had AAS at presentation. He recovered with non-steroidal anti-inflammatory drug and cervical collar.

Case Report

A six-year-old boy was admitted with history of unexplained high grade intermittent fever for one month. Along with fever he developed pain in the lower limbs and in the nape of the neck. Fifteen days after onset of fever an erythematous rash had been noticed on the chest which was evanescent and which got aggravated in the peak of fever. There was no history of joint swelling.

On examination at admission, he was febrile and had cervical and right axillary lymph-adenopathy. All movements of neck were painful especially lateral rotation and extension. There was no neurodeficit. Rest of the examina-tion including ocular findings were normal. During hospital stay he continued to have high grade fever and developed a discrete erythe-matous macular rash on his face and chest. The rash was pruritic, migratory and envanescent, lasting for a few hours and became more pronounced during fewer spikes. Linear rash developed on scratching the skin (Koebner's phenomenon).

Investigations showed hemoglobin of 9.9 g/dl, total leukocyte count of 13000/mm³ with a  differential count of P 93% and L7%. ESR fell 50 mm in the first hour. Peripheral blood film suggested hypochromic microcytic anemia and platelet count was normal. FNAC from axillary lymph node showed reactive hyperplasia. Anti-nuclear antibodies, rheumatoid factor and LE cell phenomenon were all negative. Chest X-ray and echocardiogram were normal. Lateral X-ray craniovertebral junction in flexion (Fig. 1) and extension showed mobile AAS atlanto-adontoid distance measuring 2 mm and 8 mm, respectively.

Fig. 1. Lateral X-ray craniovertebral junction in flexion showing AAS.

In view of prolonged high grade fever, neck pain with documented AAS, a typical rash and anemia with raised ESR, a diagnosis of systemic-onset JRA was established. He was put on a cervical collar and started on naproxen 15mg/kg/day. Fever responded completely after 4 weeks of starting treatment but he continued to have rash intermittently. Three months later. X-ray of cranio-vertebral junction showed correction of AAS (Fig. 2). Neck movements were better. He was continued on the same management till CT scan after 3 months (Fig. 3) confirmed resolution of AAS. ESR had reduced to 18 mm/1st hour then. Cervical collar was removed and at 1 year follow-up, the child is doing well while on naproxen.

Discussion

The upper limit of the distance between the posterior rim of the anterior arch of the atlas and the anterior margin of the dens is 4 mm in children on a lateral X-ray in flexion(4). In the index case this was 6 mm conforming to a radiologic diagnosis of AAS.

AAS is rare as a presenting feature of JRA(1). The probable pathogenesis of rheuma-toid AAS is the spread of inflammation from the atlantoaxial joint to the surrounding ligaments thereby weakening them. The weight of the head strains these already weakened ligaments specially during flexion. If the transverse ligament is thus involved, the atlas glides forward during flexion resulting in AAS.

Destruction of the dens by rheumatoid granulomatous inflammation may also produce AAS. AAS has been related in the literature to seropositivity, a longer duration of disease(5,6), high joint score index and severity of systemic disease(7). It was odd, therefore, that our patient developed AAS without having any of the high risk factors.

While it is clear from prior studies in adults that surgery is mandatory for rheumatoid patients with myelopathy(8), there are differ-ences of opinion on the management of a single horizontal or vertical spinal dislocation without neurologic complications(9). Our patient had both clinical and radiologic recovery on conservative treatment. Good results have been seen with the use of a stiff collar both in adults(10) and in children(11). Although neurologic complications from AAS are said to be rare in JRA(11) as compared to adults, it would still be worthwhile diagnosing the rare case considering its serious implications.  Moreover, such abnormalities may occur even in asymptomatic patients(9,12). Hence routine radiology of the cervical spine should be done in patients of suspected JRA. Also, a detailed neurologic examination should be done so as not to miss subtle signs of early cord compression.

References

1. Ansell BM. Joint manifestations in children with juvenile chronic polyarthritis. Arthritis Rheum 1977; 20 (Suppl): 204-208.

2. Sumi M, Kataoka O, Ikeda M, Sawamura S, Uno K, Siba R. Atlanto-axial dislocation. A follow-up study of surgical results. Spine 1997; 22: 759-763.

3. Kauppi M, Leppanen L, Heikkila S, Lahtinen T, Kautiainen H. Active conservative treatment of atlanto-axial subluxation in rheumatoid arthritis. Br J Rheumatol 1998; 37: 417-420.

4. Cassidy JT, Petty RE. Juvenile rheumatoid arthritis. In: Textbook of Pediatric Rheumato-logy, 3rd edn. Philadelphia, W.B. Saunders, 1995; pp 133-223.

5. Halla JT, Hardin JG, Vitek J, Alarcon GS. Involvement of the cervical spine in rheumatoid arthritis, Arthritis Rheum 1989; 32: 65-652-659.

6. Aggarwal A, Kulshreshtha A, Chaturvedi V,  Misra R. Cervical spine involvement in rheuma-toid arthritis: Prevalence and relationship with overall disease severity. J Assoc Phys India 1996; 44: 468-471.

7. Kauppi M, Kontinnen YT, Honkanen V, Sakaguchi M, Hamalainen M, Santavirta S. A multivariate analysis of risk factors for anterior atlantoaxial subluxation and an evaluation of the effect of glucocorticoid treatment on the upper rheumatoid cervical spine. Clin Rheumatol 1991; 10: 413-418.

8. Sunahara N, Matsunaga S, Mori T, Ijiri K, Sakou T. Clinical course of conservatively managed rheumatoid arthritis patients with myelopathy. Spine 1997; 22: 2603-2607.

9. Cats A. Rheumatoid arthritis. Practical Problems. In: Practical Rheumatology. Eds. Klippel JH, Dieppe PA. London, C.V. Mosby, 1995; pp 169-210.

10. Kauppi M, Anttila P. A stiff collar for the treatment of rheumatoid atlanto-axial sub-luxation. Br J Rheumatol 1996; 35: 771-774.

11. Fried JA, Athreya B, Gregg JR, Das M, Doughty R. The cervical spine in juvenile rheumatoid arthritis. Clin Orthop 1983; 179: 102-106.

12. Oren B, Oren H, Osma E, Cevik N. Juvenile rheumatoid arthritis: Cervical spine involvement and MRI in early diagnosis. Turk J Pediatr 1996; 38: 189-194.