Efficacy of electrotactile vestibular substitution in patients with peripheral and central vestibular loss

Abstract

Vestibular dysfunction of either central or peripheral origin can significantly affect balance, posture, and gait. We conducted a pilot study to test the effectiveness of training with the BrainPort balance device in subjects with a balance dysfunction due to peripheral or central vestibular loss. The BrainPort balance device transmits information about the patient's head position via electrotactile stimulation of the tongue. Head position data is sensed by an accelerometer and displayed on the tongue as a pattern of stimulation. This pattern of stimulation moves forward, backward, and laterally on the tongue in direct response to head movements. Users of the device were trained to use this stimulation to adjust their position in order to maintain their balance. Twenty-eight subjects with peripheral or central vestibular loss were trained with the BrainPort balance device and tested using the following standardized quantitative measurements of the treatment effects: Computerized Dynamic Posturography (CDP) using the Sensory Organization Test (SOT), Dynamic Gait Index (DGI), Activities-specific Balance Confidence Scale (ABC), and Dizziness Handicap Inventory (DHI). All subjects had chronic balance problems and all but one had previously participated in vestibular rehabilitation therapy. The scores on the clinical tests upon entry into the study were compared to their scores following training with the BrainPort balance device. Our results exhibit consistent positive and statistically significant improvements in balance, posture and gait. These results exceed what could normally be achieved in three to five days of traditional balance training alone. Since this was not a controlled study, we are unable to distinguish the degree to which these improvements are attributable to training with the BrainPort balance device versus the balance exercises performed by all subjects as a part of the BrainPort training sessions. Nonetheless, after training with the BrainPort balance device, all subjects demonstrated significant improvements in performance beyond what might be expected from conventional vestibular rehabilitation therapy.

Figures

Fig. 1.

The BrainPort Balance Device. Electrode Array.

Fig. 2.

Diagram of the electrotactile stimulation waveform for one quadrant (25-electrodes) on the 100-point Tongue Display. Active electrodes in all 4 quadrants are pulsed identically.

Fig. 3.

Relationship between head tilt position and location of tactile stimulus on the tongue. 1: Right roll; 2: Neutral; 3: Left roll; 4: Upward pitch; 5: Downward pitch.

Fig. 4.

Composite SOT scores by Age. The distribution plot of SOT composite score, before (open bars) and after (grey bars) BrainPort device therapy, by subject age (grouped in 10-year intervals). Inserts show number of subjects in each age decade (bin width) and percent of total 28 tested subjects. Age of subjects varied from 34 to 88 years, mean value was 59.1 yrs. ± 13.7 (standard deviation). Mean values of SOT composite score before (open circles) and after (solid squares) BrainPort therapy. Boxes correspond to standard error, whiskers correspond to standard deviation value (pooled variance). Note: SOT composite score improvement (distance between broken and solid lines) after standard training procedure is similar across all ages. Solid and dotted lines are fitting curves, represented by quadratic polynomial fitting function.