PD: No Neuroprotection from DBS; Dry Eye Common in PD

Subject: PD: No Neuroprotection from DBS; Dry Eye Common in PD

Date: 12/6/2005

1. Disease progression continues in patients with advanced Parkinson’s disease and effective subthalamic nucleus stimulation
R Hilker, AT Portman, J Voges, NJ Staal, L Burghaus, T van Laar, A Koulousakis, RP Maguire, J Pruim, BM de Jong, K Herholz, V Sturm, WD Heiss, KL Leenders
J Neurol Neurosurg Psychiatry 2005;76:1217-1221

Deep brain stimulation of the subthalamic nucleus does not slow progression of PD, according to this study. These findings do not support the hypothesis that suppression of glutamate excitoxicity by STN DBS might reduce nigral cell death.

Thirty patients with advanced PD received bilateral STN DBS electrode implantation. At follow-up 6 months after surgery, there was a 52% improvement in the off-med UPDRS motor score, and the daily levodopa intake had been reduced by 28% compared to pre-operative values. The UPDRS improvement was maintained largely unchanged at 16 months follow-up. PET scans obtained 4 weeks before surgery and 16 months after indicated an annual decline of radiotracer signal of 9.5%-12.9%, depending on the data analysis method.

The authors state, “Our data are in good agreement with disease progression rates reported in previous studies on medically treated PD patients,” although they note that most previous studies have examined patients earlier in the disease course. “Our PET data suggest that DBS masks rather than prevents clinical PD progression,” they conclude.

A Commentary by PC Warnke accompanies the report.

2. Tear film tests in Parkinson’s disease patients
C Tamer, IM Melek, T Duman, H Oksuz
Ophthalmology 2005;112:1795-1800

PD patients are likely to have dysfunction in tear production and symptoms of dry eye, according to this study.

Tear function tests were performed and blink rate determined in 56 consecutive PD patients, and 36 age-matched controls. Abnormal test results were more common in PD patients vs. controls for all tests (dry eye symptoms, meibomian gland disease, tear meniscus height, tear breakup time, fluorescein stain, rose Bengal stain, phenol red test, and Schirmer’s test). Dry eye was present in 87% of patients and 21% of controls, and blockage of the meibomian glands was observed in 46% of patients and 12% of controls. Mean blink rate of patients was significantly less than that of controls. The severity of abnormal results was correlated with Hoehn and Yahr score.

The authors note that the combination of low blink rate and decreased meibomian gland secretion makes PD patients especially prone to dry eye, and “PD patients should be considered at increased risk for having dry eye problems.”