InertiaLocoGraphy as a Biomarker of Immunoglobulin Therapy Efficacy in Chronic Inflammatory Demyelinating Polyradiculoneuropathy

Chronic inflammatory demyelinating polyradiculoneuropathy is a diffuse multifocal autoimmune disorder of the peripheral neuron, affecting 1 to 9 in 100,000 people. Its course is difficult to predict, and may be characterized by continuous progression, multiple relapses, or recovery after a few months. treatment. The predominantly motor form with 4 limbs represents the typical form, but the disease can take on other clinical forms (pure sensory impairment, ataxia, etc.).

In addition to induction therapy, patients most often require long-term maintenance therapy. First-line therapies, with the same efficacy according to a 2013 Cochrane study, are glucocorticoid therapy, plasma exchanges and intravenous immunoglobulin injections. Glucocorticoids have a grade C recommendation level while a grade A has been assigned to intravenous immunoglobulins and plasma exchange. However, the latter have less tolerance and have a rebound effect which limits their long-term interest. Intravenous immunoglobulins are therefore the preferred treatment today. The effect of intravenous immunoglobulins, delivered as a bolus over a few days, lasts two to six weeks, with the number of people being cured of three to improve a person. A more recent study has also shown their advantage in reducing the relapse rate at 6 months.

However, the response to intravenous immunoglobulins fluctuates in different patients and, for any given patient, changes over the course of the disease. The 2010 recommendations therefore recommend an adaptation of the doses and duration of intercourse (0.4 to 1.2 g / kg every 2 to 6 weeks) according to individual monitoring of the response to treatment. In order to embrace the diversity of symptoms of chronic inflammatory demyelinating polyradiculoneuropathy, several scores and scales are usually combined to ensure this follow-up in a cohort. Three clinical data are currently favored: the Inflammatory Rasch-built Overall Disability Scale (I-RODS), the INCAT Overall Neuropathy Limitations Scale (ONLS), the score of the Medical Research Council (MRC). However, none of them assess walking objectively.

However, patients with chronic inflammatory demyelinating polyradiculoneuropathy sometimes report significant walking disturbances, which may result from both sensory disturbances or motor disturbances present in varying degrees depending on the patient. The alterations concerned, according to the studies, the walking speed, the temporal pattern of the step, with an impairment of the durations of the different phases (support and oscillation) or the angle and the angular speed of roll at the level of the trunk. Alterations in speed and phase duration of the step improve during treatment with intravenous immunoglobulin cures, with greater sensitivity compared to the ONLS and MRC scales. The power of the propulsive moment at the ankle during the last moments of the stance phase - the push-off - is another promising gait parameter that has made it possible to distinguish diabetic patients with polyneuropathy from those without diabetes. polyneuropathy and the intensity of the deficit is linked to the severity of the attack. Gait speed, as a reflection of the subject's gait performance, and the quality of gait including the timing of gait, trunk rotation movements and push-off, therefore seem to be potential response markers. for monitoring patients treated with intravenous immunoglobulins.

InertiaLocoGraphy, quantification of gait by inertial measurement sensors, has proven its value in the evaluation of various pathologies in neurological practice, including chronic inflammatory demyelinating polyradiculoneuropathy. It gives access to the walking speed as well as to various walking quality criteria (vigor of the step, rhythmicity, regularity, symmetry, stability, fluidity, synchronization) including the times of the different walking phases and the rotational movements of the trunk, and a push-off substitute.

InertiaLocoGraphie, non-invasive, easy and quick to set up, reflecting the patient's function, therefore potentially provides biomarkers of choice for monitoring the response to intravenous immunoglobulin cures in patients with chronic inflammatory polyradiculoneuropathy demyelinating. Its association with the traditional monitoring tools such as the ONLS score, the I-ROS, and the CRM therefore appears to be of key interest for this monitoring.