Sensory information treatment during disturbed standing posture in chronic acquired demyelinating polyneuropathies (CADP).

OBJECTIVE: As proposed after stroke, the study of reactions to a sensory stimulation allows to a better understanding of postural strategies. Below, we provide the analysis in chronic acquired demyelinating polyneuropathies (CADP).

MATERIAL/PATIENTS AND METHODS: Prospective study of 25 healthy subjects (57±12years, 8M, 17F) and 25 CADP (66±14years, 20M, 5F) on stabilometric platform (Techno-Concept(®), France). Proprioception was disturbed by tendon vibration on Triceps Surae (TS) and Tibialis Anterior (TA). Vision was disturbed by optokinetic flow in 4 directions (upward, downward, rightward and leftward). Groups were compared using a composite score (mean of the center of pressure's displacement [mm] recorded in the anterior, posterior, right and left directions during the stimulation [35s]).

RESULTS: Composite score was significantly higher in CADP for optokinetic stimulation in each direction, upward (8.4/4.7mm, P=0.008), downward (9.8/5mm, P=0.0002), rightward (7/4.8mm, P=0.02) and leftward (8.4/4.5mm, P=0.001). Moreover, the higher is the sensory impairment (low score), the more important is the value of the optokinetic composite score (P=0.045, r=-0.55). Despite our expectation, CADP remained sensitive to proprioceptive stimulations: no differences were observed in healthy subjects for the TS stimulation and a more important reaction during TA vibration (7.3/5.5mm, P=0.01). Furthermore, falls were more frequent in PDCA, explaining the loss of 26% versus 2.7% of the records; P<0.0001, essentially in visual condition.

DISCUSSION-CONCLUSION: As expected, CADP are more sensitive to visual perturbation, but remained sensitive to proprioceptive perturbations despite sensory impairment. This encourages a rehabilitation aimed at promoting the recovery of proprioceptive information rather than the compensation by visual information.