44.9.4. Eye Movement

Beginning with our first studies with rehabilitation of peripheral and central balance disorders, we noticed striking effects of CN-NINM training on the recovery of visual dysfunctions (oscillopsia, abnormal nystagmus, color perception, visual acuity, light and dark adaptation, limits of visual field). Similar and even stronger effects were observed during studies with stroke, traumatic brain injury, multiple sclerosis, and Parkinson subjects. Two examples of eye movement abnormalities and rehabilitation effects of CN-NINM therapy are presented in Figures 44.10 and 44.11.

Figure 44.10

Density plot of targeted eye fixation. Eye position were recorded during a 15 second (3,000 data points) interval. Crosses, position of the targets. Position, size, and shape of each blob reflect precision and stability of fixation point. Bright colors (more...)

Figure 44.11

Eye movement before and after CN-NINM training. Smooth (sinusoidal) pursuit test, at target speed 0.1 Hz. Tested before and after CN-NINM. Subject D (stroke), 10 weeks apart, right eye presented (both eyes had similar results). Black line, trajectory (more...)

The quantitative eye movement recording tests were performed with binocular videonystagmograph VisualEyes (Micromedical Technologies).

The first case demonstrates problematic eye stabilization during a fixation task in a subject with a sport concussive injury 7 months after the incident. The subject also reported continuous hypersensitivity to light and sound, difficulty with reading books and computer screens, and attention, concentration, and short-term memory problems.

The diagram in Figure 44.10a demonstrates binocular fixation precision (distance from the target cross) and stability (size of the color spots) in a normal, healthy subject. Each spot represents the contour map of bivariate distribution of 3,000 eye position measurements recorded during 15 seconds for each target position. In Figure 44.10b (mTBI subject) there is a striking difference in a key parameter: the deviation from target position (enlarged size of spots, elongated form, and appearance of two separate clusters). After 5 days of balance and gait training with the mTBI subject (without special eye movement exercises), we found significant improvement in muscular stabilization, evidenced by more condensed spots that are more appropriately aligned both spatially and axially (Figure 44.10c). This “shrinking” of the spots reflects increased stability of the extrinsic eye muscles.

The second example, shown in Figure 44.11, demonstrates changes in dynamic eye movement control during a smooth pursuit test performed by an 82-year-old stroke subject, 4 years after incident.

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44.10. Conclusion

CN-NINM technology is a new noninvasive brain stimulation technique with potential applications in physical medicine, cognitive, and affective neurosciences (Bach-y-Rita, 2003a,2003b; Bach, 2004, 2005). This stimulation method appears to be a promising treatment of a full spectrum of movement disorders, and probably for multiple other dysfunctions associated with TBI.

Based on CN-NINM technology, our training program is designed to noninvasively induce multitargeted neural plasticity that, with consistent progressive application, affects functional changes in physical, cognitive, and sensory domains in subjects with significant dysfunction from TBI.

Examples, presented in Section 44.8, demonstrate the efficiency of our neurorehabilitation approach when applied to very complex sensory-motor functional systems such as balance, gait, movement control, and static and dynamic eye movement control. Improvement of these functional systems demonstrates recovery of appropriate spatiotemporal activation patterns in affected neuromuscular systems, which requires optimization and exquisite synchronization of multiple movement control centers and systems to function correctly and automatically.

We believe that CN-NINM technology can help to reinforce existing methods of rehabilitation therapy and approach new areas in neurorehabilitation that many considered untreatable, especially in the domain of chronic TBI.

From a future perspective, evidence of extended brain activation and simultaneous improvement of multiple symptoms typical of TBI (as well as in multiple sclerosis, Parkinson disease, and stroke subjects; unpublished results), allow us to consider CN-NINM as a core technology that can be strengthened by integration with existing methods (such as neurofeedback technology) and potentially be a complementary component of new methods not yet developed.

Though our current aim in the field of neurorehabilitation is to demonstrate efficiency of CN-NINM technology in functional improvement of acquired brain injury symptoms, we believe that future work remains to uncover the underlying mechanisms for the remarkable phenomenon we have discovered.

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