Rheumaklinik, Oskar-Alexander Strasse, 24576 Bad Bramstedt, Germany
SIR, We report the effect of etanercept therapy on mononeuritis secondary to rheumatoid vasculitis (RV). A 65-yr-old male, with a 15-yr history of refractory rheumatoid arthritis (RA), had been treated with the following disease-modifying anti-rheumatic drugs (DMARDs): hydroxychloroquine (HCQ), salazosulphapyridine (ASA), azathioprine, gold preparations, methotrexate (MTX), peroral cyclophosphamide, MTX plus ASA plus HCQ, and MTX plus cyclosporin A. Cyclophosphamide had to be stopped because of haemorrhagic cystitis and cyclosporin A because of severe hypertension. The other regimens were ineffective.
In June 1999 the patient was admitted with a highly active polyarthritis (28-joint count: 13 swollen joints) and weakness of the right foot, which had developed within the last few days. Serologically, a state of high inflammation was found: positive for rheumatoid factor (111 U/ml), Westergren erythrocyte sedimentation rate 105 mm/h and C-reactive protein 12.2 mg/dl. The actual therapy during the last 3 months had consisted of MTX 22.5 mg i.v. weekly, 3 g ASA/day, 400 mg HCQ/day and a continuous dose of prednisolone (10 mg daily). Neurological examination revealed right-sided paresis of dorsiflexion and eversion of the right foot (score 23 according to The British Medical Research Council). Tendon reflexes were normal. The patient complained of hyperpathy in the dorsum of the right foot. Electromyography (EMG) revealed axonal neuropathy with spontaneous activity (fibrillation potentials and positive sharp waves) in muscles innervated by the common peroneal nerve, and a highly rarefied interference pattern. Amplitudes of the motor unit potentials were normal (about 0.5 mV). Unsuspicious nerve conduction studies excluded compressive neuropathy of the common peroneal nerve.
Because of the high RA activity and assuming that the mononeuritis was a manifestation of RV, we initiated additive therapy with 25 mg etanercept twice weekly for 6 months. Treatment with MTX, ASA, HCQ and prednisolone 10 mg/day was continued. Clinical and serological assessments were performed before the initiation of treatment with etanercept and were repeated weekly in the first month and once a month thereafter. A neurological examination was performed before treatment began and after 3 and 6 months. X-rays of the joints (hands, feet, cervical spine) were performed before treatment began and after 6 months.
Within 4 weeks, the patient achieved an ACR 70% response, and the effect was sustained over the 6 months of additive therapy with etanercept. The combination treatment was well tolerated, without side-effects. Palsies regressed markedly, reaching a score of 4 after 3 months. EMG now did not show any spontaneous activity. Motor unit potentials became polyphasic and amplitudes increased to 5 mV. There was a slight to moderate reduction in the interference pattern. After 6 months the patient's clinical status was almost normal. EMG revealed mild signs of residual axonal neuropathy. The joint erosions showed no progress after 6 months.
The rapid improvement of RA following treatment with etanercept is well documented [1, 2]. To our knowledge, we describe the first successful application of etanercept therapy in a patient with mononeuritis secondary to RV. Peripheral nerve involvement is a common presentation in rheumatoid vasculitis [3]. The treatment of RV usually consists of high-dose prednisolone and DMARDs (e.g. azathioprine) [4] or, in severe cases, of cytotoxic immunosuppressive drugs, such as cyclophosphamide [5].
Our patient had characteristics predisposing him to the development of RV: male gender, the presence of rheumatoid factor and a severe course of RA with joint erosions. Furthermore, rapid neurological deterioration within a few days is common in vasculitis. Other relevant causes, such as diabetes mellitus, sarcoidosis, vitamin deficiency, neoplasia and alcoholism, were ruled out.
Because of the rapid progress of motor dysfunction and the high RA activity, we initiated additive treatment with etanercept instead of i.v. cyclophosphamide; the latter had not been tolerated by this patient in the past. Etanercept led to a dramatic improvement of the joints within a few weeks and to almost complete remission of the paresis within several months. Further studies are needed to determine the effectiveness of etanercept in treating RV.
Notes
Correspondence to: C. Richter.
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