Largest and Longest Follow-up Study of Parkinson's Patients
Shows Substantial Benefits of Brain Surgery Maintained

Toronto researchers have found that the benefits of a surgical procedure for Parkinson's patients in which dysfunctional brain cells are destroyed by an electrical current are maintained two years following surgery.

The study, the largest and longest of its kind of late-stage Parkinson's patients undergoing pallidotomy, is published today (October 9, 1997) in the New England Journal of Medicine.

Pallidotomy, a procedure initially performed in the 1960s, was discontinued with the introduction of levadopa (l-dopa), a medication to treat Parkinson's disease. L-dopa initially proved to be an effective treatment. However over time, it has resulted in severe side effects causing uncontrollable movements known as dyskinesias and variable control in the symptoms of Parkinson's. The Toronto Hospital decided to revisit and re-evaluate this surgical procedure four years ago as a viable treatment for Parkinson's disease. Contributing to this decision was the advancement of state-of-the-art diagnostic technology such as magnetic resonance imaging (MRI), increased understanding of brain physiology and the severe side effects associated with l-dopa.

The patients in the two-year study were evaluated while they were both on and off their Parkinson's medication (l-dopa) before and after surgery. The study found that while patients were off their medications there was:

• a 28 per cent reduction in motor scores i.e. reduction in stiffness, tremors and slowness of movement
• a 29 per cent increase in the ability to perform activities of daily living such as feeding and dressing
• up to 50 per cent decrease in levels of dependency on others in various tasks
  

While on their medications, the study found:

• an 82 per cent reduction in dyskinesias on the side opposite of surgery
  (because the right side of the brain controls the left side of the body and vice versa patients are operated on the side of the brain controlling the side of the body suffering the most severe symptoms)
• a 44 per cent improvement in dyskinesias on the same side of surgery
• a 30 per cent improvement in activities of daily living
• minimal change in motor scores, i.e. other Parkinson's symptoms
  such as stiffness and tremor which had generally continued to respond to l-dopa
  
  

"We found a substantial improvement in motor skills and activities of daily living following the two-year follow up," says principle investigator Dr. Anthony Lang, Director of the Movement Disorders Centre at The Toronto Hospital and Professor, Department of Medicine, University of Toronto.

"The benefits seen during the off-medication state as well as the reduction in dyskinesias on the side of the body opposite to surgery were sustained for a minimum of two years," Dr. Lang says. "And the improvement in the activities of daily living while patients were on their medication was probably due to the most striking effect of pallidotomy which is the improvement of dyskinesias."

Not all the benefits, however, were long-lived, Dr. Lang says. Improvements to walking and stability on the feet only lasted six months while the reduction in dyskinesias on the same side of surgery were lost between one and two years of follow up.

"This information will help doctors decide who will benefit the most from this procedure," Dr. Lang says. "For instance, a patient with asymmetrical symptoms (one side of the body affected more than the other) will benefit greatly. While the patient who has exclusive walking problems and minimal l-dopa-induced dyskinesia would be a poor candidate for pallidotomy."

Thirty-nine patients were enrolled in the study and followed for six months. Of these, 27 were followed for one year; of this group, an additional 11 were followed for two years.

Parkinson's disease is a chronic, slowly progressive disease of the nervous system. Its causes are unknown, however, its major symptoms may include tremor, muscle rigidity, slowness of movement and difficulty with balance and walking.

For more information, contact Josey Panetta, Senior Media Relations Officer, The Toronto Hospital, 416-340-3303.

Return to The Toronto Hospital