Repetitive task practice is an important component of physical therapy intervention for many patients/clients with neurologic diagnoses, including those with tetraplegia. A high level of practice intensity in the form of increased numbers of repetitions has been shown to maximize therapeutic benefit in many clinical populations. However, the current clinical environment is often at odds with this principle. Decreased levels of reimbursement and low numbers of available therapy visits limits the availability of resources to provide intense interventions. With the pressure to achieve ever better functional outcomes for our clients, physical therapists need novel techniques that augment repetitive task practice and maximize the benefit of every repetition in clinically feasible time frames.
The study by Gomes-Osman and Field-Fote1 in the current issue provides important insight into one possible tool for augmenting repetitive task practice, noninvasive brain stimulation. Noninvasive brain stimulation refers to an external, transcranial stimulus that can be used to excite or inhibit motor cortex activity. A growing body of research suggests that excitatory brain stimulation combined with the practice of skilled, goal-directed tasks can increase training effects over task practice alone in adults without disabilities.2 Gomes-Osman and Field-Fote1 aimed to determine whether this beneficial effect would also be found in individuals with chronic tetraplegia who had persistent upper extremity impairment. Using a double-blind, cross-over design, they showed that 3 days of repetitive task practice of an upper extremity task improved arm and hand function. However, the benefit of repetitive task practice was enhanced with the addition of repetitive transcranial magnetic stimulation (rTMS), a form of noninvasive brain stimulation.
While preliminary, the findings reported in this study are promising. Moderate to large effect sizes were found when repetitive transcranial magnetic stimulation (rTMS) was combined with training, even though the training dose provided in this study was modest (approximately 10 total training minutes per day for 3 days). Such a protocol could feasibly be provided within the time frame of a physical therapy visit. Additional research is needed to determine whether this type of intervention, provided in a larger dose, produces long-term benefits to arm function in individuals recovering from spinal cord injury.
An interesting and important finding of this study was the transfer effect found in the untrained hand. That is, improvement in hand function was found in the hand that did not physically perform the practice task during training. In addition, the improvement in the untrained hand was greater when the training of the contralateral hand was performed in combination with rTMS. Such an effect may have great importance in individuals with tetraplegia who often present with bilateral upper extremity deficits. The positive transfer effects found by Gomes-Osman and Field-Fote1 suggest that clinicians may be able to target practice on the more impaired arm after tetraplegia but expect improvements in both arms. While additional research is needed in a larger sample, this finding provides preliminary support for another avenue to maximize each practice repetition within the time constraints of the clinic environment.
While the use of noninvasive brain stimulation as an adjunct to repetitive task practice is in need of further research, this study suggests that this type of protocol may be a promising tool to improve arm and hand function after spinal cord injury. The noninvasive cortical stimulation approach used by Gomes-Osman and Field-Fote1 is not currently approved for clinical use. However, continued research like that outlined in this study is needed to determine the optimal use of brain stimulation in varied patient populations in anticipation of its arrival in the clinic in the future. The data presented in this study support the development and implementation of a larger trial with a longer training duration and a follow-up assessment in individuals with incomplete tetraplegia. Future research will answer several important questions on the use of brain stimulation after tetraplegia: What are the best brain stimulation parameters to optimize motor improvement? What is the optimal dose of brain stimulation when paired with repetitive task practice? Which individuals with tetraplegia will benefit most from brain stimulation combined with repetitive task practice?
While clinicians wait for further evidence on the benefit of adding noninvasive brain stimulation to task practice, several clinically relevant points can be taken from the current study. Incorporate repetitive task practice of skilled, upper extremity tasks into treatment for individuals with tetraplegia; there is potential for physical therapists to have a positive effect on arm function. Be sure to measure for possible effects in both the trained and untrained arm; practice in one arm may benefit both. Consider utilizing other modalities to augment repetitive task practice that are currently clinically available, such as peripheral nerve electrical stimulation.3 And keep an eye out for exciting new ways to augment our interventions to maximize each practice repetition in the future.
1. Gomes-Osman J, Field-Fote EC. Improvement in hand function in adults with chronic tetraplegia following a multi-day 10 Hz rTMS intervention combined with repetitive task practice. J Neurol Phys Ther. 2015; 39:23–30.
2. Reis J, Robertson EM, Krakauer JW, et al. Consensus: Can transcranial direct current stimulation and transcranial magnetic stimulation enhance motor learning and memory formation? Brain Stimul. 2008;1:363–369.
3. Hoffman L, Field-Fote E. Effects of practice combined with somatosensory or motor stimulation on hand function in persons with spinal cord injury. Top Spinal Cord Inj Rehabil. 2013;19(4):288–299.