Target-oriented recommendations for rehabilitation by correlative analyses of morphofunctional, intramuscular, electrophysiological and MR-based properties of back muscles in patients after spondylodesis and traumatic brain injury

Status:

completed 05/2015

Aims:

In the previous project FR 0122 (see further informations) in patients after spondylodesis coordination disturbances and degradation effects of paraspinal muscles could be verified.

Following spondylodesis of the spine, instabilities occur again and again during follow-up treatment. To date, their etiology is still only insufficiently understood. The current research project addressed the question of the influences that could have a pathogenetic effect to this finding for designing future therapy and rehabilitation more effectively.

Activities/Methods:

Therefore, the influences of different surgical techniques (open/percutaneous) were evaluated as were the performed stabilization itself independent of the applied surgical technique, the location of the primary injury, potential interactions induced by central nervous motoric disorders as well as further factors with a view to their impact on the active, stability mediating function of the back muscles. To this end, the partners in this cooperative project applied surface electromyography (SEMG) and MR spectroscopy and performed biomechanical simulations as well as histological analyses.

Patients with spinal injuries and patients with traumatic brain injury were examined at multiple times of investigation with a follow-up time of up to one year after the injury and underwent both static and dynamic load situations. With respect to the electrophysiological measurements during static load, patients were subjected to several different, well defined partial loads of their own upper body weight. In addition, MR spectroscopy was performed in a subpopulation of the patients during which they also performed a static endurance exercise. The dynamic load included gait analyses on a treadmill with SEMG data being again acquired. Furthermore, model-based biomechanical simulations of different static load situations were performed.

Results:

Compared to a healthy control group, all patients revealed reduced SEMG amplitudes six weeks after injury, with the exception of the conservatively treated patient group that showed higher amplitude values. All operated patients had a modified spatial SEMG amplitude distribution pattern of their back muscles when compared to healthy controls that was independent from load level. This finding was supported by the biomechanical simulations, which revealed a considerably greater effect of the stabilization of the spine segment itself and its location in comparison to the actually applied surgical technique. In accordance with this, the spatial activation characteristics of the back muscles converged during follow-up only for the patient group with traumatic brain injury to that of the healthy controls. Following an intermediate improvement of the electrophysiological findings of patients with spine lesions with an approach to the corresponding values of the control group, the results became distinctly worse after one year. These electrophysiological results are supported by MR spectroscopic findings, which revealed a tendency of increased fatigability of the back muscles. In line with these results, the histological preparation of the available muscle biopsies showed a decline of type II fibers with an increased connective tissue fraction. With respect to the dynamic load examination, all patient groups had distinctly changed muscle activities with reduced amplitudes during heel strike covering the whole paravertebral region but with dramatically increased amplitude maxima during the swing phase in the lumbar and thoracolumbar region.

In summary, none of the two compared surgical techniques turned out to be superior to the other; rather the effect of the stabilization itself and its location are functionally important. The worsening of the functional findings one year after injury underlines the importance of long-term rehabilitation programs for patients with spine injuries.

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