Arnold’s Neuralgia Complicating Rheumatoid Arthritis: About a Case Report and Literature Review

Introduction: Described in 1834, Arnold’s neuralgia is a headache of cervical origin secondary to irritation or compression of the large posterior occipital nerve and/or the small occipital nerve. Headaches are unilateral, and evolve in paroxysms. The etiologies of NA are many and varied. They may be vascular, neurological, arthropathic or systemic, including rheumatoid arthritis. We report a Senegalese case of NA in a patient treated for RA, and then establish the current state of this association in the African region. Observation: This 47-year-old patient had been treated for 17 years for sequelae of rheumatoid arthritis (RA), and was seropositive for both rheumatoid factor and anti-citrullinated peptide antibodies. The levels of these autoantibodies were 103 IU/ml and 4000 IU/ml respectively. Polyarthritis was predominantly acromelic, characterized by ankylosing deformities. Since diagnosis, she had been treated with methotrexate (15 mg, then 20 mg per week), folic acid at a dose equivalent to methotrexate, and hydroxychloroquine (400 mg per day). Prednisone 10 mg corticosteroid therapy was administered on admission and gradually discontinued after two years’ follow-up. Recent symptomatology was marked by a polyarticular, poly synovial flare-up over the past 6 months. In addition, the patient reported paroxysmal cervical pain. It was lateralized to the right, with tension and electric discharges. The rheumatological examination, in addition to the aforementioned joint disorders, revealed pain provoked by palpation and mobilization of the cervico-occipital hinge. Cervical mobilization was limited, particularly to flexion and extension movements. Biological tests revealed an inflammatory syndrome, with a sedimentation rate of 76 mm, a C-reactive protein (CRP) of 87 mg/l, and a microcytic hypochromic anemia with a hemoglobin level of 8.6 g/dl. Cervical computed tomography revealed fusion of the atloido-axoid joint, with geodes and erosions on the edges of the anterior arch of C1, with no atloido-axoid dislocation detected. The electro-neuro-myogram (ENMG) showed a neurogenic pattern. This cervical symptomatology was compatible with Arnold’s neuralgia. However, because of the ankylosis, the neurosurgeons did not recommend surgical decompression. Medical treatment was therefore reinforced by the addition of pregabalin (150 mg daily) and physiotherapy sessions. The short-term outcome was favorable, with partial pain regression. Conclusion: The originality of our case lies in the rarity of cervical spinal involvement in Africa. On the other hand, the fact that Arnold’s neuralgia was discovered remains exceptional, whatever the population studied.