Posted by freedom2001 on September 19, 2003, at 10:56:27
CAN A TREATMENT FOR PARKINSON’S DISEASE HELP ALLEVIATE OCD?
HONOLULU— —High-frequency subthalamic stimulation has proven efficacy in treating patients with Parkinson’s disease, and now a report suggests that the technique may also be effective in treating patients who have obsessive-compulsive disorder (OCD). French investigators discovered this possibility after evaluating the outcomes of two patients with a history of severe OCD who subsequently developed Parkinson’s disease. Bilateral stimulation of the subthalamic nucleus immediately improved parkinsonian disability in both patients. Two weeks after the procedure, compulsions also completely disappeared in both patients, and obsessive symptoms improved by 58% and 64% in the two subjects.“These results indicate that bilateral chronic high-frequency stimulation of the subthalamic nucleus can improve OCD,” stated Luc Mallet, MD, PhD. Dr. Mallet presented his team’s findings at the 55th Annual Meeting of the American Academy of Neurology. Dr. Mallet is affiliated with the CNRS UMR 7593 and Psychiatirc Department, Pavillon Clérambault, GH Pitié-Salpêtrière, Hôpital de la Salpêtrière, Assistance Publique-Hôpital de Paris.
Dr. Mallet and colleagues implanted subthalamic electrodes to alleviate parkinsonian symptoms in two patients. In the first patient, the right therapeutic electrode was placed between the anteromedial part of the subthalamic nucleus and the zona incerta, and the left electrode was placed in the anterior part of the zona incerta. In the second patient, the right and left therapeutic electrodes were placed within the anteromedial part of the subthalamic nucleus and between the anteromedial part of the subthalamic nucleus and zona incerta. Clinical evaluations were performed one month before and six months after neurosurgery.
The first patient was a 51-year-old woman with a five-year history of Parkinson’s disease who had severe levodopa-induced motor complications despite optimized treatment. She had a history of OCD from age 18. Her symptoms included cleaning all rooms in her home three times and repeatedly arranging perfume bottles on the bathroom shelf; in addition, she was afraid of being found dead in a dirty house. Those symptoms were unaffected by the long-term administration of levodopa. Two weeks after the operation, the patient claimed that she was more pleased about the disappearance of her OCD symptoms than by the moderate improvement in Parkinsonian disability.
The second patient was a 50-year-old man with a 16-year history of Parkinson’s disease who suffered severe dyskinesias and motor fluctuations. His OCD began at age 10. One example of his compulsions was repeatedly checking locks as many as 10 times in succession, a habit that tended to decline in adulthood but became exacerbated with the onset of Parkinson’s disease. Two weeks after neurosurgery, the compulsions disappeared, and obsessions had markedly diminished.
Anxiety and depression were improved in both patients with no apparent change in cognition. “It may be assumed that inhibition of limbic striato-pallido-subthalamic-pallido-thalamo-cortical neuronal systems was responsible for the improvement of OCD,” stated Dr. Mallet. “This hypothesis is in agreement with the current pathophysiologic model of OCD, suggesting a dysfunction of a cortico-striato-pallido-thalamo-cortical circuitry.”
The research team originally published their findings in the October 26, 2002, Lancet. In that article, they pointed out that because the electrodes were implanted medially to the lateral hypothalamus, which is known to regulate emotions, they cannot exclude the possibility that stimulation of the lateral hypothalamus contributed to the change in the patients’ behaviors. They noted that although the intensity of stimulation was moderate and not applied directly to the lateral hypothalamus, they believed that the improvement of obsessive-compulsive symptoms in the patients was probably mediated by the subthalamic nucleus.
“Despite the partial efficacy of medical treatment, the management of patients with severe OCD remains a challenge,” the researchers reported in Lancet. “The recovery from OCD that we report in two patients with Parkinson’s disease raises the possibility that high-frequency stimulation could improve the functions of subcortical limbic circuitry in patients with severe OCD.”
—Colby Stong
Suggested Reading
Mallet L, Mesnage V, Houeto J-L, et al. Compulsions, Parkinson’s disease, and stimulation. Lancet. 2002;360:1302-1304.
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