February 20, 2023

expert reaction to electrical stimulation of the spinal cord for upper limb recovery after stroke in 2 patients

A study published in Nature Medicine looks at the use of epidural stimulation of the spinal cord for post-stroke upper-limb paresis.

Prof Nick Ward, Professor of Clinical Neurology and Neurorehabilitation at UCL Queen Square Institute of Neurology, said:

“This is a nice study which is using an approach used in promoting walking in spinal cord injury, novel in chronic stroke upper limb recovery. It does however only look at two patients, but is an exciting proof of concept.

“The idea here is to increase the excitability of the spinal cord motoneurons (start of the nerves that travel to the muscles from spinal cord). This means that any signals coming from the brain/brain stem that have been weakened by the stroke will have a better chance of activating the nerve and so the muscle, achieving new movement or better control over existing weak movement when the device is on. This creates a window during which practice could lead to more longer lasting improvements that will remain when device turned off. If there are no signals arriving at the motoneurons after stroke, then this approach will not work – so some work needs to be done to understand who it will work for and how we make those assessments (i.e. stratification based on likelihood of response – important for designing future clinical trials).

“Other approaches have involved changing excitability of cells in the cortex (non-invasive brain stimulation, vagal nerve stimulation, drugs e.g. fluoxetine) under the banner of ‘plasticity modification’ but have not translated into useful clinical approaches so far. One approach has tried to increase excitability in brain stem neurons (reticulospinal pathways), but there is just one small proof of concept study.

“So the overall approach is to increase excitability of parts of pathway that sends signals from brain to muscles affected by stroke. Most approaches have tried to change cortex, one has tried to change brain stem , this is trying to do it at the level of spinal cord. To be clear, none work on their own. All will need to be combined with ‘training’.”

‘Epidural stimulation of the cervical spinal cord for post-stroke upper-limb paresis’ by Marc P. Powell et al. was published in Nature Medicine at 16:00 UK time on Monday 20^th February.

DOI:10.1038/s41591-022-02202-6

Declared interests

Prof Nick Ward: “My background is running the upper limb rehab programme at Queen Square as an academic neurologist.”