Long-term neurophysiological and clinical response in patients with chronic inflammatory demyelinating polyradiculoneuropathy treated with subcutaneous immunoglobulin.

ABSTRACT

OBJECTIVE: To assess the long-term effects of subcutaneous immunoglobulin (SCIg) on neurophysiological and clinical parameters in patients affected by chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). METHODS: 16 drug-naïve CIDP patients, fulfilling the clinical and neurophysiological criteria for typical CIDP, were treated with one cycle of intravenous immunoglobulin (IVIg) (0.4 g/kg/day for 5 consecutive days) and then shifted to the subcutaneous treatment (SCIg) (0.4 g/kg/week) after 4 weeks. Patients were evaluated (i) at the diagnosis (t0), (ii) after 4 weeks since the last IVIg infusion (t1), and (iii) after long-term treatment with SCIg (t2 = 12 months; t3 = 24 months) by (1) neurophysiological parameters of nerve conduction studies and (2) clinical assessment scales for evaluation of (a) strength, by medical research council (MRC) sum score, (b) sensory functions, by inflammatory neuropathy care and treatment (INCAT) sensory sum score and (c) disability, by overall disability sum score (ODSS). RESULTS: Long-term SCIg treatment induced a significant improvement of neurophysiological parameters, in particular primary demyelinating features of nerve conduction, and clinical variables. Correlation analysis showed (1) a direct positive correlation between the MRC sum score and the amplitude of the distal compound muscle action potential (dCMAP) amplitude, (2) an inverse correlation between dCMAP amplitude and ODSS score, and (3) an inverse correlation between sensory nerve action potential (SNAP) amplitude and the INCAT sensory sum score. CONCLUSIONS: Our findings revealed a significant long-term effect of the SCIg treatment on the neurophysiological parameters, associated with improvement of global strength, sensory deficits and overall disability in patients with CIDP. SIGNIFICANCE: Early start of the SCIg treatment after IVIg infusions induced a significant and long-term improvement of clinical and neurophysiological parameters in CIDP patients.