Effects of robot-driven gait orthosis treadmill training on the autonomic response in rehabilitation-responsive stroke and cervical spondylotic myelopathy patients
Introduction
In the last decade, a new therapeutic strategy based on body weight supported (BWS) treadmill training (BWSTT) assisted with a robotic-driven gait orthosis has been proposed as a clinical tool helpful during rehabilitation in gait-impaired individuals [1], [2], [3].
Robotic-assisted locomotion is adjustable in force, BWS and speed so that even patients with severe loss of sensory-motor function can exercise in an environment delivering as much challenge as can be handled. Improvements after robotic-assisted BWSTT include a greater weight-bearing capacity, an increase in walking speed and endurance, an improved gait pattern during BWSTT [4] and, in some cases, an increased ability to walk over ground [5]. While the effect on the motor skills have been deeply assessed, no studies have explored the effects of a rehabilitation protocol based on robotic-assisted BWSTT on the autonomic nervous system (ANS) response in subjects with lost motor skills such as stroke (ST) and cervical spondylotic myelopathy (CSM) patients. In both these populations ANS is impaired. Indeed, it was reported a reduced vagal modulation in ST patients [6], [7] and a decreased sympathetic activity in CSM patients [8]. The assessment of the effects of a rehabilitation protocol not only in terms of an improvement of motor skills but also in terms of recovery of the cardiovascular regulation might permit a more complete evaluation of the rehabilitative process.
In a previous study [9] we showed that a traditional robotic-assisted BWSTT rehabilitation session including standing, walking at different speeds and recovery induces a light but significant cardiovascular response that can be typified using short-term analysis of heart rate variability (HRV). In addition, in [9] we demonstrated that symbolic analysis outperforms spectral analysis in assessing the ANS response to a robotic-assisted BWSTT rehabilitation session.
The aims of this study are: (1) to evaluate the ANS response during robotic-assisted BWSTT protocol in ST and CSM populations; (2) to study the effects of a 6-week daily repetition of a robotic-assisted BWSTT rehabilitation session on the ANS regulation in the same groups of patients. Our study was carried out over ST and CSM patients who exhibited an improvement of their motor skills after robotic-assisted BWSTT rehabilitation therapy (i.e. rehabilitation-responsive subjects) to test the hypothesis of the additional improvement of the cardiovascular regulation. The assessment of the ANS response was carried out by applying symbolic analysis to short-term HRV [9].
Section snippets
Population
The following patients were included in our study: (i) ST patients with hemiparesis as a result of a first cerebral ischemia or hemorrhage according to the definition of the World Health Organization (N = 5, mean age 61 ± 10.5 years, 4 men); (ii) patients suffering from CSM (N = 6, mean age 64.5 ± 5.2 years, 5 men).
Table 1 summarizes the main characteristics of our populations. Only patients with post-injury time interval larger than 12 months were enrolled. Additional inclusion criteria for ST
Results
Fig. 1 shows the result of the motor skills indexes during PRE and POST conditions. A significant increase of FIM (limited to the assessment of walking items) and Barthel indexes (both p ≤ 0.05) after the rehabilitation period was found in both groups, while the trunk control test and the JOA index showed a tendency to increase in ST and CSM patients respectively. Motricity index did not vary in ST patients.
Fig. 2 shows an example of RR series during PRE (left panels) and POST (right panels)
Discussion
The major findings of the study are: (1) individual ANS responses to the first BWSTT rehabilitation session were variable and scattered in ST patients; (2) ANS responses of ST patients after 30 daily BWSTT rehabilitation sessions were characterized by a reduction in the inter-subject variability and by the presence of trends more similar to those observed in healthy subjects [9]; (3) individual responses to the first BWSTT rehabilitation session were variable and scattered in CSM patients
Conclusions
Using as a reference the typical response of healthy subjects to a robotic-driven BWSTT rehabilitation session reported in [9], we conclude that our robotic-driven BWSTT rehabilitation therapy is helpful in restoring cardiovascular control in rehabilitation-responsive ST patients and limiting excessive vagal responses in rehabilitation-responsive CSM patients. Since our robotic-driven BWSTT therapy induces mainly passive movements, the improvement observed in the cardiovascular response cannot
Conflict of interest
No conflict of interest.
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