Gray Matter Volume May Indicate Efficacy of Acupuncture for Migraine

Presence and location of gray matter (GM) in the brain may indicate whether acupuncture is an effective method of treating migraine without aura (MwoA), according to a study published in Frontiers in Neurology.

In many countries acupuncture is used as a treatment for migraine, but there is insufficient evidence to claim it is effective for all migraineurs. According to researchers, “about 50% of patients do not achieve substantial improvement after acupuncture.” However, determining which patients may benefit from acupuncture will prevent nonresponders from undergoing time-consuming and unsuccessful treatment.

The present study included 41 individuals with MwoA, divided into legitimate acupuncture and sham groups. Each participant completed 4 weeks of acupuncture treatment and kept a headache diary to record frequency, symptoms, and duration of each migraine. Magnetic resonance imaging (MRI) scans were completed before and after the intervention period, at least 3 days after each individual’s prior migraine attack. Patients who reported having at least a 50% reduction in the number of migraine days were considered acupuncture responders.

To distinguish GM differences in regions of the brain, a qualitative MRI program known as the Computational Anatomy Toolbox automatically evaluated the differences without using prior information to define anatomical borders.

A machine learning model was then used to “distinguish responders from non-responders based on pre-treatment brain (GM) volume” and determine longitudinal changes in GM predictive regions.

In total, 19 individuals (46%) reported a 50% reduction in the number of migraine days. “Based on 10-fold cross-validation for the selection of GM features, the linear support vector machine produced a classification model with 73% sensitivity, 85% specificity, and 83% accuracy,” researchers said. The area under the receiver operating characteristic curve was reported as 0.7871.

Specifically, investigators found reductions in the number of migraine days correlated with baseline GM volume in the cuneus, parietal, and frontal gyri in all patients. Responders’ left cuneus also exhibited a longitudinal increase in GM volume.

“The efficacy of acupuncture was greatest in those patients with the lowest baseline GM volume in the middle frontal/inferior gyrus and cuneus and the greatest baseline GM volume in the parietal gyrus,” they concluded.

Researchers hope pretreatment GM volume measurement can act as an objective potential biomarker for the efficacy of acupuncture treatment in patients with migraine. “With the increasing use of acupuncture therapy worldwide the ability to predict the acupuncture outcome would contribute to the development of individualized treatment and promote its wider application.”

Reference

Yang X, Liu L, Xu Z, et al. Baseline brain gray matter volume as a predictor of acupuncture outcome in treating migraine [published online March 5, 2020]. Front Neurol. doi: 10.3389/fneur.2020.00111.