Sensorimotor postural rearrangement after unilateral vestibular deafferentation in patients with acoustic neuroma

Preoperative balance control compensation in patients with a vestibular schwannoma: Does tumor size matter?

“…This result complements previous postoperative studies that demonstrated better postural performances at middle and long-term time-points after surgical VS removal, compared to pre-surgery measurements (Parietti-Winkler et al, 2006. Taken together, these results suggest that neural adaptive mechanisms implemented to compensate for vestibular dysfunction related to tumor growth lead to lower balance performances than after uVD.…”

“…This demonstrated that patients benefited from the redundancy of sensory inputs in balance control situations, allowing them to engage in a sensory reweighting that compensated for the disturbance in their vestibular function. This type of sensory reweighting has been previously observed soon after uVD (Lacour et al, 1997;Borel et al, 2002;Parietti-Winkler et al, 2006). Consequently, one can hypothesize that preoperative adaptive mechanisms might share similar processes with those implemented after surgery, but either these preoperative mechanisms are less efficient, or they partly differ from the postoperative adaptive ones.…”

“…The composite equilibrium score (C ES ) was a weighted average of the patient's overall performance during all of the trials for the six conditions. To identify the significance of each sensory system's influence on postural control, a sensory ratio were calculated (Parietti-Winkler et al, 2006): the R SOM , R VIS , and R VEST ratios represent the somatosensory, visual, and vestibular contribution to postural control, respectively. The ability to rely on vision, even if inadequate (R PREF ), and the ability to manage altered proprioceptive inputs (R PMAN ) were also evaluated (Nashner and Peters, 1990;Black et al, 1995).…”

“…This decompensation explains why most patients report severe vertigo immediately after surgery and present an impairment in postural performances (Parietti-Winkler et al, 2006). The variations in the postural performances follow a well-described time-course, characterized by degradation just after surgery and then recovery and improvement over the pre-surgery condition at longer time points after the surgery.…”

“…The variations in the postural performances follow a well-described time-course, characterized by degradation just after surgery and then recovery and improvement over the pre-surgery condition at longer time points after the surgery. This recovery is related to the implementation of central adaptive mechanisms, which entails substitution by other sensory afferences, efference copy/reafference copy reconciliation, and new behavioral strategies (Parietti-Winkler et al, 2006.…”