The spinal cord is extremely vulnerable to injury, however, unlike other parts of the body this extension of the brain does not have the ability to repair itself when damaged. A spinal cord injury (SCI) occurs when there is damage either from trauma, loss of blood supply, or pressure due to a tumor or infection. The main goal of rehabilitation in humans with SCI is to strengthen transmission in spared neural networks. Although neuromodulation has the ability to target many different sites within the central nervous system to restore motor function following SCI, the role of cortical targets remains poorly understood.  Now, a study from researchers at the University of Miami uses a non-invasive cortical target in the brain to enhance hand motor function in patients with SCI.  The team states their study provides the first evidence that cortical targets in the frontal lobe could represent a novel therapeutic site for improving motor function in humans paralyzed by SCI.  The study is published in the journal Brain.

Previous studies show in movement disorders neuromodulation targets brain structures, such as cranial nerves, the spinal cord, and the peripheral nervous system via electrical or neurochemical stimulation.  Usually, electrical epidural spinal cord stimulation is used to alleviate various disorders of the motor system in patients with SCI.  It has been hypothesized neurostimulation may lead to the development of new nerve pathways or reawaken pre-existing connections between the brain and limbs.  The current study provides the first evidence that cortical targets could represent a novel therapeutic site for improving motor function following SCI.

The current study utilizes noninvasive transcranial magnetic stimulation over the primary motor cortex, one of the principal brain areas involved in motor function housing corticospinal neurons.  Results show the activity of corticospinal projections to intrinsic finger muscles increased in SCI patients and uninjured participants for 30 to 60 minutes after the stimulation. Data findings show individuals with SCI were able to exert more force and electromyographic activity with finger muscles after the stimulation showing an enhanced ability to grasp small objects with their hands.

The lab states their study provides several pieces of important information regarding the development of strategies to improve function following SCI. They go on to add contrary to years of dogma, their study demonstrated positive functional plasticity potential persists within the sensorimotor system for years after an SCI.

The team surmises their study provides a novel long-term cortical target to repair hand motor output in humans with SCI.  For the future, the researchers state they are now testing the effect of this intervention when given on consecutive days in patients exhibiting more severe muscle paralysis.

Source: University of Miami

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