Inspired by Kim et al and Zhai et al 2022.[1,2]
DTI – diffusion tensor imagingkey to acronyms
MRI – magnetic resonance imaging
FA – fractional anisotropy
EA – electroacupuncture
TCSS – Toronto clinical scoring system
I am sitting on a hotel room balcony in Bologna following an international medical acupuncture conference and contemplating the subject for this week’s blog. I met a host of colleagues from South Korea at the conference, and then this novel paper from South Korea popped up on my PubMed search today. It is also linked by DTI to an older paper from earlier this year that I have kept in my ‘recent’ folder on Zotero, so I will highlight them both here. Both are firsts as far as I can tell, so they deserve a mention on the blog.
I came across DTI for the first time thanks to a study run by Vitali Napadow, and discussed on this blog under the rather compelling title ‘Rewiring the brain with acupuncture.’
DTI is a method of quantifying diffusion of protons (the H’s in H2O) in a specific location using a method closely related to MRI. If the tissues have a very ordered structure, such as tracts of neurones all running in the same direction, then the water molecules can only diffuse freely along those tracts. This results in a high measure of fractional anisotropy (FA), and thus this technique can be used to assess changes in these neural structures during recovery from stroke or used to monitor improvements with treatments for neuropathy.
In the first paper, 35 patients with subacute stroke (within 3 months of either ischaemic or haemorrhagic stroke) were randomised to usual rehabilitation or usual rehabilitation plus EA. EA was performed daily, 5 days a week for 4 weeks. The details of EA in the paper are limited, and the text refers to other papers. So, I had to follow those references, and it looks as though the EA would have been applied to the hemiparetic limbs – 6 points in the arm and 6 in the leg. They mention using 30Hz frequency and stimulation within the individual patient’s tolerance.
The outcomes were measured using standard functional scales (Fugl-Meyer assessment and modified Barthel index) as well as with DTI. The DTI was applied to the corticospinal tracts and referred to a tractography.
It is not surprising that there were no differences in the functional outcome scales between the groups in this relatively small study, since both groups would have had relatively intense physical rehabilitation. There were, however, significant differences measured by DTI in the corticospinal tracts of patients who received 20 sessions of EA.
Previous research has suggested that improvements in FA in corticospinal tracts and other brain areas are associated with improvements in motor recovery.
The second paper also used DTI as an outcome, but this time applied to peripheral nerves (tibial and common peroneal) in patients with diabetic peripheral neuropathy. 40 patients were randomised to receive daily injections of mecobalamin (methylcobalamin) either in the hip or bilaterally at ST36 for 2 weeks.
The group receiving bilateral injections at ST36 had significantly greater improvement in in both clinical score (TCSS) and FA measurements after 14 days.
1 Kim MS, Moon BS, Ahn J-Y, et al. Elucidating the mechanisms of post-stroke motor recovery mediated by electroacupuncture using diffusion tensor tractography. Front Neurol 2022;13:888165. doi:10.3389/fneur.2022.888165
2 Zhai Y, Yu W, Shen W. Diffusion Tensor Imaging Evaluates Effects of Acupoint Injection at Zusanli (ST36) for Type 2 Diabetic Peripheral Neuropathy. Med Sci Monit Int Med J Exp Clin Res 2022;28:e935979. doi:10.12659/MSM.935979
3 Wen H, Alshikho MJ, Wang Y, et al. Correlation of Fractional Anisotropy With Motor Recovery in Patients With Stroke After Postacute Rehabilitation. Arch Phys Med Rehabil 2016;97:1487–95. doi:10.1016/j.apmr.2016.04.010
4 Bril V, Perkins BA. Validation of the Toronto Clinical Scoring System for diabetic polyneuropathy. Diabetes Care 2002;25:2048–52. doi:10.2337/diacare.25.11.2048