ABSTRACT
BACKGROUND: Non-invasive current stimulation can induce neuroplastic changes in the normal brain, including visual system structures. Because it is not known if such plasticity is of clinical value, we wished to learn if vision restoration can be induced after optic nerve damage. METHODS: In an open-label, clinical observational study 446 patients with optic nerve lesions were treated with non-invasive repetitive transorbital alternating current stimulation (rtACS). Current bursts (<1000 µA, 5-20 Hz) were applied to induce phosphenes for one or two 10-day stimulation periods. Efficacy was assessed by monocular measurements of visual acuity and visual field (VF) size. EEG recordings at rest (n = 68) were made before and after treatment and global power spectra changes were analyzed. RESULTS: rtACS improved VF size in the right and left eye by 7.1% and 9.3% (p < 0.001), respectively. VF enlargements were present in 40.4% of right and 49.5% of left eyes. Visual acuity (VA) significantly increased in both eyes (right = 0.02, left = 0.015; p < 0.001). A second 10-day course was conducted 6 months in a subset of 62 patients and resulted in additional significant improvements of VA. Analysis of EEG power spectra revealed that VA and VF improvements were associated with increased alpha power. Increased theta power was observed in patients that had only VF enlargements but no VA change. In contrast, non-responders had increased delta power spectra in frontal and occipital areas. CONCLUSIONS: rtACS leads to long-lasting improvements in VA and VF size and after-effects in EEG power spectra. Because physiological and clinical parameters are correlated we hypothesize that rtACS enhances plasticity by inducing synchronization in different cortical regions, but the precise mechanisms needs further clarification. These encouraging results require confirmation by controlled clinical trials.
Subject(s)
Electric Stimulation Therapy/methods , Optic Nerve Diseases/physiopathology , Optic Nerve Diseases/therapy , Orbit/physiology , Visual Fields/physiology , Adult , Aged , Electroencephalography , Female , Humans , Male , Middle Aged , Observation , Optic Nerve Diseases/etiology , Orbit/radiation effects , Retrospective Studies , Treatment Outcome , Visual Field Tests , Visual Fields/radiation effects , Young AdultSubject(s)
Adaptation, Physiological , Cerebrospinal Fluid , Optic Atrophies, Hereditary/physiopathology , Optic Atrophy/physiopathology , Vision Disorders/physiopathology , Adolescent , Adult , Child , Chronic Disease , Electroencephalography , Evoked Potentials, Visual/physiology , Female , Humans , Male , Middle Aged , Neurotransmitter Agents/cerebrospinal fluid , Optic Atrophies, Hereditary/complications , Optic Atrophies, Hereditary/diagnosis , Optic Atrophies, Hereditary/rehabilitation , Optic Atrophy/complications , Optic Atrophy/diagnosis , Optic Atrophy/rehabilitation , Transplantation/methods , Vision Disorders/diagnosis , Vision Disorders/etiology , Vision Disorders/rehabilitationABSTRACT
The results of the clinical electroencephalographic examination of 222 adult epileptics show that the cerebral temporal lobes are fairly frequently involved in the pathological process. A specific state of irritation of the left temporal lobe alone is observed in different periods of pathological process compensation: after the epilepsy, in the clinical remission and in the interictal period. Stereotaxic destruction of the amygdaloid complex in the right temporal lobe may substantially diminish the manifestations of epileptic generalization. The data obtained indicate a functional specialization of the cerebral hemispheres in epileptic patients.
