Role of the Visual Afferent Stream in Recovery of the Postural Control in Different Periods after Craniocerebral Injury

Abstract

A comprehensive posturographic (PG), electroencephalographic, and clinical examination was performed during rehabilitation in 17 patients (mean age 27.5 ± 7.4 years) who had suffered a severe craniocerebral injury (SCCI). Of these, nine were examined soon after the SCCI and eight, in the period of remote consequences of the SCCI. The patients were compared to a control group of 18 healthy subjects (mean age 27.8 ± 12.2). The PG studies showed that, in the healthy subjects, the amplitude of sway of the common center of pressure (ACCP) in the absence of the visual control was higher than with the eyes open. The ACCP was higher in the sagittal than in the frontal plane and decreased during optokinetic stimulation. In the control group, rhythmic photostimulation produced a local increase in interhemispheric EEG coherence in symmetrical occipital and parietal cortical areas. In the patients examined early after the SCCI with the eyes open, the ACCP was higher than in the healthy subjects, especially in the frontal plane. The ACCP did not decrease in the Romberg posture and increased during optokinetic stimulation. In these patients, rhythmic photostimulation was accompanied by a generalized increase in mean interhemispheric EEG coherence as compared to the resting level. In the remote period after the SCCI, the PG and EEG responses to a decrease or an increase in the visual afferent stream proved to be inverted: the patients stood better with the eyes closed than with them open and photostimulation produced a decrease in EEG coherence in the occipitoparietal areas of the cortex. The results confirmed a greater efficiency of rehabilitation in the early period after the SCCI. Thus, specific PG and EEG reactions were observed in the SCCI patients at different stages of recovery. The generalized reactivity and “infantile” features of the EEG and PG rearrangements characteristic of the early period after the SCCI were considered to be a favorable prognostic sign for the recovery of the integrative brain activity and postural control of a patient. The inversion of the reactions in the remote period after the SCCI testified to limited possibilities of the recovery of the impaired functions and was indicative of a pathological type of compensatory rearrangements.