Rehabilitation for Postural Deformities in Parkinson�s Disease: An Update and Novel Findings

Various treatments, such as antiparkinson drugs [2-4], deep brain stimulation [5-9], lidocaine injection [10,11], botulinum toxin injection [12-15], spinal magnetic stimulation [16], orthosis and physiotherapy [16] were administered to improve postural deformities, but there is insufficient evidence concerning the effectiveness of these treatments. Possible mechanisms involved in postural deformities in PD patients are dystonia, rigidity, drugs, myopathy, degenerative spinal changes, soft tissue changes, and proprioceptive disintegration [1]. Among these, soft tissue changes and proprioceptive disintegration seem to be improved by rehabilitation.

Soft tissue changes such as decreased flexibility of joints and muscles, muscle weakness, and decreased muscle endurance has been assumed to affect postural deformities in PD patients and interventions for soft tissue changes are usually adopted to PD patients with postural deformities. Trunk-specific training such as stretching and strengthening exercise in a functional context decrease trunk flexion angle and lateral trunk flexion angle while standing in PD patients with mild to severe lateral trunk flexion [17]. Physical rehabilitation including stretching and strengthening exercise of trunk and lower limb may reduce painful abdominal muscle contractions and improved lateral trunk flexion angle in PD patients with severe lateral trunk flexion [18].

Santamato et al. [13] reported that botulinum toxin injections into the paraspinal muscles and rehabilitation program consisting of stretching and agility exercise improve lateral trunk flexion angle in a PD patients with pisa syndrome. Furusawa et al. [10] reported that repeated lidocaine injections into external oblique muscle improved trunk flexion angle and was maintained for 90 days by additional subsequent daily rehabilitation program that emphasized trunk extension in PD patients with upper camptocormia. Combined treatment with rehabilitation and injections such as botulinum toxin and lidocaine could be a useful treatment strategy for PD patients with severe postural deformities such as pisa syndrome and camptocormia with abnormal activity of truncal muscles.

Proprioceptive disintegration could affect impaired vertical perception in PD patients with postural deformities, especially lateral trunk flexion. Lateral trunk flexion increased when PD patients with lateral trunk flexion closed their eyes [19]. This phenomenon supports the notion concerning the relationship between the proprioceptive disintegration and lateral trunk flexion in PD patients. Prolonged body tilt to one side induces a bias in the perception of body verticality, even in the healthy subjects [20]. Because PD patients with lateral trunk flexion that develops in the chronic fashion is tilted to one side for a long time, the perception of body verticality is assumed to be biased additionally.

Postural reeducation could improve trunk posture both in the frontal and sagittal planes to some extent [21]. Postural reeducation exercise aims to promote proper postural realignment in sagittal and frontal plane. Combination of postural reeducation exercise with intervention for proprioceptive discrimination exercise at the patients’ back might additionally enhance their awareness of trunk position and promote adjustment. If PD patients could hardly correct postural abnormalities, physiotherapist might adopt compensatory devices such as truncal orthosis [22], high frame walker and backpack for camptocormia [23] and crutches for pisa syndrome. It is also important for physiotherapists to know these compensatory devices.
 

The characteristics of soft tissue changes have not been clarified, although the Interventions for soft tissue changes described above have been adopted in PD patients with postural deformities. In future studies, it should be that characteristics of soft tissue changes in PD patients with postural deformities are clarified and the interventions for soft tissue changes are selected in each PD patients with postural deformities. Moreover, the characteristics of the impairments of vertical perception remained to be clarified. Scocco et al. reported that both PD patients with and without pisa syndrome showed the deviations of vertical perception discussed these deviations cannot explain the lateral deviation of the posture in PD patients with pisa syndrome [24]. However, their study design was cross sectional, and the relationship between deviations of the vertical perception and pisa syndrome was inconclusive. Further, there has been no study investigating the vertical perception in the sagittal plane in PD patients with camptocormia. The perception of body verticality is important to generate motor program for the frontal and sagittal postural control. On the basis of understanding of the characteristics of vertical perception in PD patients with postural deformities, effective postural reeducation programs should be investigated in the future research.
 

It was reported that PD patients with lateral bending posture have vestibular dysfunction which was ipsilateral to the leaning side [25]. The vestibular system detects angular and linear acceleration in the sagittal, frontal, and horizontal planes, and we hypothesized that vestibular function is bilaterally impaired in PD patients with anterior bending posture. Galvanic vestibular stimulation (GVS) is a method that stimulates vestibular system. Electrodes are attached to the mastoids behind the subject’s ears to stimulate the vestibular system by low direct current. GVS has been used in neurophysiological experiments and otological tests [26]. Recently, there have been some reports in which GVS was used as an intervention strategy in PD patients and stroke patients with unilateral spatial neglect or pushing symptoms [27-30]. In our previous study we reported that binaural monopolar GVS, which stimulates with the cathode electrode of each pair over the mastoid process and the anode electrode over the trapezius muscle on the same side and likely activates both sides of vestibular system, improved the anterior bending angle in a PD patient with camptocormia [28]. Because this study was a single case study and did not compare with sham stimulation, the effects of GVS on camptocormia were not clarified.

Binaural bipolar GVS, which stimulates with the cathode over one side of the mastoid process and the anode over the other side of the mastoid process and activate vestibular system on the cathode side, shifts vertical perception of healthy subjects to the anode side during stimulation, but the shift was reversed toward the cathode side after the stimulation [31]. To improve lateral bending posture, binaural bipolar GVS might be better than binaural monopolar GVS. There is some possibility that GVS will be a novel intervention in PD patients with postural deformities. After the tendency of the bias of the vertical perception in PD patients with anterior bending posture and those with lateral bending posture are clarified, the effectiveness and of both types of GVS on these postural deformities and the appropriate stimulation method for each postural deformities should be investigated in the future study.

Visual feedback tools such as mirror, picture and video are applied in postural reeducation exercise described above, since the performance of postural orientation task is improved by using of the visual information in PD patients [32,33]. Augmented feedback is considered to be important for motor learning in the postural control task in PD patients [34]. Accordingly, we developed the system providing patients with augmented feedback in the form of the present anterior and lateral bending angles during training [35] (Figure 1). Test-retest reliability, concurrent validity, and accuracy of the system in measurement of anterior and lateral bending angle during standing were confirmed [36,37]. The system uses the Kinect sensor and detects posture without attaching sensors to user’s body. Lower frequency of visual feedback about the knowledge of results is generally better to promote motor learning [38]. Conradsson et al. reported that highly challenging and progressive training for postural control was feasible in mild to moderate PD patients [39]. It might be better that the frequency of the visual feedback in our developed system is adjusted to motor learning process. The appropriate frequency of the visual feedback in the motor learning process needed to be investigated. By combining the system and information and communication technology, it becomes possible that patients perform visual feedback training to improve posture by themselves at home, and that healthcare professionals remotely check the implementation status and the results of visual feedback training and provide patients with advice or feedback about the results.

Additionally, our developed system enables healthcare professionals to evaluate patients’ anterior and lateral bending angles during standing at home. To date, healthcare professionals could not evaluate patient’ posture at home after the discharge from the hospital or after the outpatient care, and patients could not convey the information about how their posture is at home. The system potentially solves these issues and provides novel forms of in-home rehabilitation and patient centered outcome that healthcare professionals really want to evaluate.