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.

Deep brain stimulators can improve movement problems in people with primary dystonia.

They are implanted either near the collar bone or the abdomen and connected by a wire to electrodes placed in the brain. A tiny generator sends electrical pulses to the brain to control movement.

In this study, Vidailhet attached the leads to the globus pallidus internus area of the brain, the same brain region targeted in dystonia patients.

After a year, eight out of the 13 people had improvements in motor symptoms, Vidailhet reported in Lancet Neurology.

The average improvement on a movement rating scale was 24.4 percent, but responses ranged from 21 percent to 55 percent in eight patients.

Two patients had little benefit and three had no benefit or symptoms worsened slightly.

The treatment also reduced disability and pain, and generally patients felt better and had fewer symptoms of depression and other mental health problems. However, five patients needed treatment with anti-anxiety drugs.

While the results may offer promise for some patients, the team said the study was small and the findings should be interpreted with caution.

They called for further studies to evaluate the effect of deep brain stimulation on more complex and more common types of cerebral palsy, particularly in children.

Medtronic's deep brain stimulation devices are already approved to treat Parkinson's disease, tremors, dystonia and for certain patients with severe obsessive-compulsive disorder.

The company is also studying the devices in patients disabled by stroke. (Editing by Maggie Fox and Vicki Allen)