At the European Congress of Neurorehabilitation (ECNR), recently held in Vienna, new findings from rehabilitation research were presented.
As most recently at the American Academy of Neurology (AAN) in Washington in 2015, the focus of the scientific lectures was on the technique of NIBS (non-invasive brain stimulation). Yet the technology applied has been known for more than 100 years. As early as 1886, in his “Handbook of Electrotherapy”, Wilhelm Heinrich Erb described the principle of direct-current electrical stimulation. In his self-experiment performed in 2005, Michael Nitsche took on this old technique (Fig. 2). Since then, a large number of studies have been published; the evidence of this treatment method is currently still low (Cochrane Collaboration, transkranielle Galvanisation zur Wiederherstellung der Aktivitäten des täglichen Lebens nach Schlaganfall [Cochrane Collaboration, transcranial galvanization for restoration of daily living activities after a stroke (Elsner et al., Syst. Rev. 2013)].
NIBS comprises transcranial direct-current stimulation (tDCS and TMS – transcranial magnetic stimulation and immediate transcranial direct-current stimulation). These techniques make it possible to facilitate brain structures or inhibit their activity in order to control neuroplasticity. With the two methods mentioned above, neurorehabilitation can address a wide range of indications: Stroke, craniocerebral trauma, focal dystonia, neuropathic pain, and spinal cord injury. Unlike earlier therapeutic approaches, NIBS is now being applied during rehabilitative measures as well. At the AAN, the Working Group of the University Hospital San Raffaele in Milan presented an interesting study on this subject. This study used TMS and simultaneous Motomed training – a form of cycling with motor-driven movement training devices – to improve dorsiflexion of the ankle. This was based on the evidence that walking ability is reduced after strokes, accompanied by decreased force of dorsiflexion in the affected foot. The Milanese team studied the effects of TMS with simultaneous Motomed training on the patients’ ability to walk. In this study, the effect of bilateral repetitive transcranial magnetic stimulation (rTMS) using an H-coil in combination with Motomed training was studied in terms of the function of the exercises in chronic stroke patients more than six months post-stroke. A randomized, double-blind, placebo-controlled crossover study was conducted. With this study design, 63 % responders were found in the active treatment group, and 9 % responders in the sham stimulation group. Overall, improvement of the functions of the affected lower extremity could be achieved. Another interesting result was a decrease in spasticity according to the modified Ashworth scale. However, no changes in walking speed could be achieved. Perhaps this can be explained by the cycling training itself, where there was obviously no carry-over effect in terms of walking speed. The measured effects were, however, still evident even after a month.
Forms of neuroplasticity
Upon application of TMS, short-term and long-term changes occur in the brain. Long-term effects are synaptic plasticity (LTP, LTD), production of neurotrophic factors, and expression of genes. In principle, neuroplasticity takes place in the primary motor cortex and the dorsal pre-motor cortex ipsi- and contralaterally to the lesion. Two forms of neuroplasticity can be distinguished:
- Lesion-induced neuroplasticity: Enlargement of the cortical representation of muscles proximal to the lesion (= optimum utilization of intact structures, a direct reaction to cell death)
- Training-induced neuroplasticity: Increased use of a limb leads to enlargement of the cortical representation (Sterr 2004). Furthermore, non-use leads to a decrease of cortical representation. In the context of neurorehabilitation, the two types of neuroplasticity intertwine. Loss of nerve cells leads to increased excitability in the area of the lesion, but also contralaterally. In chronic stroke, mainly training-induced neuroplasticity comes to fruition.
For stroke prognosis, it was found that the greatest functional improvement takes place during the first few weeks to months; thus, early initiation of rehabilitation is mandatory. However, prognosis appears very variable, depending inter alia on the size and location of the lesion. Prognostic neurophysiology / imaging: Motor-evoked potentials: with measurably better prognosis for motor functions (Stinear et al. 2007, Brain 130, 170–180). EBM (evidence-based medicine) rehabilitation: In principle, it should be noted that according to the Cochrane Stroke Rehab “Review of Reviews” 2014, a therapeutic intensity of more than 20 hours of therapy is required. Furthermore, in Neurology, 2014, Pandian could demonstrate the effectiveness of mirror therapy in the treatment of neglect. Overall, the differences between the active therapies are only moderate. In pareses of upper extremities, bilateral arm training or mirror therapy was likewise found superior (Kupar et al. 2010). EBM / lower extremity / walking ability: High training intensity necessary: To learn how to walk again, one must walk (Quotation: Hesse, Berlin). Moreover, context-specific walking even outside the treatment rooms proves an important therapeutic content. Treadmill training to restore the ability to walk has been established for a long time; early use of aids for walking is expedient (Chakar et al. 2010). In addition to gait training, functional strength training of the lower limb seems to be an important further treatment content. Regarding the ability to walk, there is no functional difference between a peroneal splint and functional electrical stimulation (van Swigchem et al., 2011). In ambulatory patients, no superiority of robotic versus conventional physiotherapy was found (Hidler 2009). For non-ambulatory patients, early mobilization while still in the stroke unit is critical. In the study by Cumming in 2011, it was shown that patients who were mobilized within 24 hours after the stroke could be re-enabled to walk twice as quickly.
Pharmacotherapy in neurorehabilitation
On the part of pharmacotherapy, there are currently no new developments in the market. The FLAME study conducted in 2011 by Chollet et al. still seems to effect significant improvement of the function of the upper extremity in the first three months. It is unclear whether this effect is persistent as well. The L-dopa study by Scheidtmann 2001 concerning improvement of walking ability and the function of the upper extremity yielded negative results in subsequent studies. Currently no recommendation can be given for L-dopa therapy after stroke. Depending on stimulation pattern, frequency, and intensity, changes occur in the stimulated brain area. In principle, at a stimulation frequency of ≤ 5 Hz, increased excitability can be detected in the stimulated area; on the contrary, low-frequency stimulation – for example, 3 Hz – results in decreased excitability in the stimulation area. As early as 2005, Hummel et al. described the potential therapeutic effects for the treatment of post-stroke deficiencies. It is important to note that NIBS and motor training show synergistic effects in terms of neuroplasticity (Hsu 2012). This example clearly shows where neurorehabilitation is heading. In the future, NIBS techniques should increasingly be combined with motor training. The combination of stimulation of central and peripheral structures opens up new perspectives for neurorehabilitation (Fig. 1). The advantages of tDCS are primarily in the relatively low purchase price; a further advantage of this method is the high flexibility and portability of the therapeutic device. Both therapies have already been found safe with few contraindications – for example epilepsy.
Summary for practice
Early start on the acute neurological ward is necessary. Furthermore, evidence-based therapies should be applied; there is no clinical superiority of individual therapeutic schools. As before, there are no standard programs in neurorehabilitation; therapy must be planned for each patient in syndrome-oriented fashion. For interdisciplinary communication and definition of the therapeutic goals, the concept of ICF appears expedient in daily routine. Furthermore, new technical methods should be incorporated into neurorehabilitation (tDCS, TMS, robotics, FES etc.). Especially in depressed patients, pharmacotherapy should not be neglected.
Neurological rehabilitation is well organized in Austria. Overall, there were 2000 beds approved in 2014. Over the next few years, due to the demographic development a disproportionately high increase in neurorehabilitation is to be expected. Overall, however, more funding is required for neurorehabilitation research. In patients in the chronic stage of stroke, inclusion of neurophysiological studies for patient selection would have to be considered for resumption. Tele-rehabilitation methods are likewise already making their way into clinical practice in neurological rehabilitation. However, it remains to be decided who shall ultimately control these therapy units and take corrective action, and how tele-rehabilitation measures are going to be funded in the future.
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