Levodopa and neuropathy risk in patients with Parkinson disease: Effect of COMT inhibition.

OBJECTIVE: Our purpose was to determine whether the use of catechol-O-methyltransferase-inhibitors (ICOMT) can reduce the risk of developing levodopa (LD)-induced neuropathy in Parkinson's disease (PD) patients. METHODS: A multicentre study of 197 PD patients was performed. 144 were exposed to LD for more than three years (LELD group); 53 simultaneously assumed Entacapone for at least eighteen months (LELD_ICOMT group). RESULTS: The prevalence of neuropathy in LELD patients was 19.4% whereas it was 5.7% in LELD_ICOMT group with a significant difference (p = 0.025). In LELD_ICOMT cohort the daily LD dose and serum VB12 levels were significantly higher (p < 0.0001), the serum Hcy levels were significantly lower (p = 0.001) compared to LELD group. CONCLUSION: Our results suggest that ICOMT could have a protective effect on the development of LD-induced neuropathy. Their action probably occurs through the metabolic rebalancing of the one-carbon-pathway cycle and is independent of the PD duration and severity and the duration of LD intake.

Neuropathy and levodopa in Parkinson's disease: evidence from a multicenter study.

The objectives of this study were to evaluate the risk of neuropathy in patients with Parkinson's disease (PD) and to evaluate the role of levodopa exposure as a potential risk factor. A multicenter study of 330 patients with PD and 137 healthy controls with a comparable age distribution was performed. With respect to levodopa exposure, 144 patients had long exposure (≥ 3 years) to levodopa (LELD), 103 patients had short exposure (<3 years) to levodopa (SELD), and 83 patients had no exposure to levodopa (NOLD). Nerve function was evaluated using the reduced total neuropathy score. Right sural sensory antidromic and peroneal motor nerve conduction studies were performed by neurophysiologists who were blinded to the existence of neuropathy clinical features or PD treatment. Overall, 19.40% of patients in the LELD group, 6.80% in the SELD group, 4.82% in the NOLD group, and 8.76% in the control group were diagnosed with neuropathy (axonal, predominantly sensory). Multivariate logistic analysis indicated that the risk of neuropathy was not influenced by disease duration, severity, or sex. The risk of neuropathy increased by approximately 8% for each year of age (P < 0.001; odds ratio [OR], 1.08; 95% confidence interval [CI], 1.037-1.128). The risk of neuropathy was 2.38 higher in the LELD group than in the control group (P = 0.022; OR, 2.38; 95% CI, 1.130-5.014). In a comparison between patients with and without neuropathy (Student's t test), the levodopa dose was higher (P < 0.0001), serum vitamin B12 levels were lower (P = 0.0102), and homocysteine levels were higher (P < 0.001) in the patients with neuropathy. Our results demonstrate that the duration of exposure to levodopa, along with age, is the main risk factor for the development of neuropathy. Screening for homocysteine and vitamin B12 levels and clinical-neurophysiological monitoring for neuropathy may be advisable in patients with PD who are receiving treatment with levodopa.

Efficacy and safety of quetiapine treatment for delusional parasitosis: experience in an elderly patient.

Delusional parasitosis is an unusual psychiatric disorder characterized by the false and persistent belief of being infested by parasites. Treatments include haloperidol, pimozide, and at present, olanzapine and risperidone. We report a case of delusional parasitosis in an elderly man, in which the treatment with low doses of quetiapine induced the complete remission of the syndrome, without any considerable side effects. No such report has been described before.