Small vestibular schwannomas can cause gait instability

To confirm whether detailed gait analysis can detect gait instability in patients with small vestibular schwannoma (VS) with an apparently normal gait.

Twenty-two patients (7 males, 15 females; 40-64 years old) with small VS and nine healthy age- and weight-matched controls were enrolled. Small VS was defined as the longest diameter less than 20mm from the porus acusticus internus on MRI with no brainstem compression. Each subject was asked to walk straight for a distance of 8m with tactile sensors attached to both feet, and repeat two trials with eyes open and closed. Gait variables of stance, swing, double support, stability, and average length of the trajectories of the center of force (TCOF) during stance were recorded and analyzed.

No significant differences in the stability of the TCOF were found during gaits with eyes open and closed between the two groups. No obvious changes in gait variables were recognized with eyes open between the two groups. However, under gait with eyes closed, the values of the coefficient of variation (CV) of the gait phase were significantly greater in stance and swing in the VS group than in the normal group. In addition, patients with canal paresis (CP) showed greater CV values in gait phase related parameters than those who without CP during gait with eyes closed.

Patients with small VS may have an apparently normal gait, but their vestibular deficit could be detected by proper use of gait analysis, especially with visual deprivation.