Cerebellum Stimulation Improves Gait and Balance After Stroke

November 30, 2018

Use of transcranial magnetic stimulation to the cerebellum promoted gait and balance recovery in stroke patients in a new study.

"We showed a clear increase in walking ability and balance with this treatment aimed at a novel target in the brain — the cerebellum," lead author Giacomo Koch, MD, Santa Lucia Foundation, Rome, Italy, told Medscape Medical News. "Our work opens up the cerebellum as a new area of the brain of interest in recovery of stroke patients."

Koch noted that previous studies of stimulation of the area of the brain affected by the stroke have not produced satisfactory results.

"So we tried a different approach," he said. "Although the cerebellum is not normally directly affected by a stroke, studies in heathy controls have suggested that stimulation of the cerebellum can lead to increased activity across the whole neural network."

Stroke patients often have to relearn very simple motor functions, he noted, "and the cerebellum is a key structure in recovery after a stroke — it is very important for learning motor skills, so we focused on trying to increase activity in the cerebellum to promote reorganization of the neural network."

The study was published online November 26 in JAMA Neurology.

In the article, the researchers note that gait and balance impairment due to limb deficit after stroke is one of the main factors associated with poorer functional recovery. Because gait is a critical determinant of independent living, improvement of walking function is one of the major goals of stroke rehabilitation.

Balance dysfunctions have substantial impact on functional independence and overall recovery, they write. However, there are no well-defined protocols for the rehabilitation of gait in patients who have experienced stroke.

The investigators point out that the cerebellum is strongly involved in functional reorganization of the motor network during recovery after stroke. In animal models of stroke, the stimulation of cerebellar cortical networks was found to improve functional recovery, and fMRI studies have shown that activity in the contralesional cerebellum positively correlates with gait recovery in patients with stroke.

"Patients often have to relearn simple motor strategies, a mechanism that is controlled by the cerebellum," Koch added.

The randomized, double-blind, sham-controlled phase 2a study included 36 patients who had had an ischemic stroke at least 6 months previously in the contralateral middle cerebral artery with hemiparesis.

They were randomly assigned to receive either treatment with a novel form of repetitive transcranial magnetic stimulation known as intermittent θ-burst stimulation or sham stimulation applied over the cerebellar hemisphere ipsilateral to the affected body side immediately before physiotherapy for about 15 minutes daily for 3 weeks.

Results showed that patients treated with active stimulation experienced an improvement of gait and balance functions. In addition, there was a pronounced increase in mean Berg Balance Scale (BBS) score, which was the study's primary outcome.

The mean BBS score increased from 34.5 at baseline to 43.4 after 3 weeks of treatment. It continued to increase — to 47.5 — up to 3 weeks after the end of treatment. In contrast, there was no significant change in score for the group that received sham stimulation.

The analysis of effectiveness showed that BBS scores improved by 23.1% in the active stimulation group and by 10.3% in the sham group.

The researchers say the BBS increased "from a level in which patients need assistance for walking to a level of independent walking."

It also indicates "a significant reduction of the risk of falling, passing from a medium fall risk to a low fall risk," they add.

"These are very promising results," Koch said. "We saw an improvement at the end of the 3-week treatment period which was still there another 3 weeks later. Patients went from quite a high risk of falling to a low risk of falling. This is an important clinical gain."

Walking disability after stroke is difficult to treat, he added. "After this treatment, they could walk relatively independently, which will have a major effect on their quality of life — it means they can go out on their own, go to the shops, etc," he said.

The researchers note that "walking functions tend to decline more at 6 months from stroke onset after a transient initial improvement, and such deficit is associated with long-term disability and reduced quality of life."

They add that improvement with this cerebellar stimulation was achieved in a relatively short period of training, which shows that this approach "can be useful to design fast, low-cost, and effective protocols for gait rehabilitation."

No significant overall treatment-associated differences were noted in two secondary endpoints — the Fugl-Meyer Assessment, which assesses fine motor function in the hand, and the Barthel Index, which measures activities of daily living.

Patients treated with active stimulation, but not sham stimulation, also showed a reduction of step width at the gait analysis (from 16.8 cm to 14.3 cm) and an increase of neural activity over the posterior parietal cortex, as measured on electroencephalography. The posterior parietal cortex is important for gait and balance.

The authors explain that a lack of gait stability after stroke can lead to a larger step width as the patient compensates for the greater sway of the body in the frontal plane. "Therefore, the reduction of step width should be considered a clear sign of the improvement of gait stability."

Koch added that the current research raises the possibility of exploring other methods of stimulating the cerebellum.

"One approach could be to investigate the use of direct current stimulation — this produces a weaker stimulation, as it does not use magnetic fields, but it is much cheaper and would therefore be more accessible," he suggested.

The study was funded by grants from the Italian Ministry of Health. Dr Koch has disclosed no relevant financial relationships.

JAMA Neurol. Published online November 26, 2018. Full text

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