Treatment of refractory chronic inflammatory demyelinating polyneuropathy with interferon β1B

Abstract

Sirs: Chronic inflammatory demyelinating polyneuropathy (CIDP) is an immune-mediated neuropathy [13] characterized by symmetrical sensory and/or motor symptoms persisting for more than 8 weeks. The disease course may be progressive or relapsing [13]. On the basis of randomized trials, high dose intravenous immunoglobulin (IVIg), corticosteroids and plasma exchange have been established as effective treatments for CIDP. The main limitations of these approaches are lack of long term efficacy, difficulties in their use and high costs; thus, alternative immunosuppressive treatments have been proposed (azathioprine, cyclosporine and cyclophosphamide) [2, 9, 11]. The immune-mechanisms responsible for CIDP resemble those implicated in multiple sclerosis (MS) [13], thus making CIDP the peripheral counterpart of MS. In addition, similar to MS, neuropathological studies support heterogeneity of CIDP pathogenesis, with concomitant demyelination and axonal damage [13]. Some studies have recently been performed to evaluate the usefulness of Interferon (IFN) β1a in CIDP patients unresponsive to conventional therapies [1, 7, 14]. We present the case of a 43year-old woman, who in July 1997 complained of progressive weakness in both lower limbs, as well as sensory symptoms. Clinical symptoms persisted until December 1997 and a diagnosis of CIDP was made according to INCAT criteria [3]. Neurological examination revealed generalized areflexia, while an electrophysiological study showed partial conduction block for stimulation at the fibular head of peroneal nerves (–50 % amplitude on the right and –49 % on the left) and absent F wave on the left median nerve and right peroneal nerve. Cerebrospinal fluid analysis produced evidence of albuminocytological dissociation (total protein 82 mg/dL without cells) and isoelectrofocusing was within normal limit. After a first treatment schedule of IVIg with a good response, she became refractory to this treatment. She presented nine relapses throughout 27 months (treated with plasma exchange with transient and partial response) despite the specific drugs used (Figure). In July 2001 she started IFNβ-1b (Betaferon) 8MUI with subcutaneous injections every other day. No other relapses occurred. At present, she has been relapsefree for 40 months and shows marked improvement in clinical conditions (Table 1). Nerve conduction studies also showed marked improvement in motor and sensory velocities (Figure). In April 2002, serological examination showed the presence of anti-thyreoglobulin and anti-thyroid peroxidase antibodies, with an increase in free triiodothyronine and free thyroxin. Autoimmune thyreopathy was diagnosed, and the patient started treatment with an antithyroid drug. IFN beta has been proven efficient in treating MS [4, 5, 12] reducing the number of relapses. Due to clinical similarities between MS and CIDP, there is emerging interest in the use of IFN in CIDP. As far as we know, this is the first report in which IFNβ-1b has been used to treat a CIDP patient. Our patient showed good clinical and neurophysiological response to long-term IFNβ1b treatment (40 months). The stabilization observed was judged by the absence of relapses. IFN beta acts as an immunomodulatory agent, exerting its action at different levels in the inflammatory process. Two recombinant forms of IFN beta are used in clinical practice: IFNβ-1a and INFβ-1b. The use of IFNβ-1a in the treatment of CIDP is controversial, and contradictory results have been reported in different studies [1, 6, 12]. It should be noted that LETTER TO THE EDITORS