Device shows promise to treat cerebral palsy type

* Medtronic device helped in hard-to-treat condition

* Eight out of 13 patients benefited

* More study needed

By Julie Steenhuysen

CHICAGO, July 1 (Reuters) - Zapping the brain with a mild electrical current appears to help patients with a difficult-to-treat form of cerebral palsy, French researchers said on Wednesday.

Patients in the study were implanted with pacemaker-like devices known as deep-brain stimulators made by Medtronic Inc (MDT.N), which helped fund the study.

A team lead by Marie Vidailhet of Salpetriere University Hospital in Paris implanted the devices in 13 people who had cerebral palsy with dystonia-choreoathetosis, a common and progressively disabling movement disorder.

About 10 percent of patients with cerebral palsy have this condition, which is a secondary cause of dystonia, a movement disorder marked by involuntary muscle contractions.

There are no effective treatments.