Subthalamic nucleus stimulation in Parkinson's disease : anatomical and electrophysiological localization of active contacts.

OBJECTIVES: 1 - To assess the anatomical localization of the active contacts of deep brain stimulation targeted to the subthalamic nucleus (STN) in Parkinson's disease patients. 2 - To analyze the stereotactic spatial distribution of the active contacts in relation to the dorsal and the ventral electrophysiologically-defined borders of the STN and the stereotactic theoretical target. METHODS: Twenty-eight patients underwent bilateral high-frequency stimulation of the STN (HFS-STN). An indirect anatomical method based on ventriculography coupled to electrophysiological techniques were used to localize the STN. Clinical improvement was evaluated by Unified Parkinson's Disease Rating Scale motor score (UPDRS III). The normalized stereotactic coordinates of the active contact centres, dorsal and ventral electrophysiologically-defined borders of the STN were obtained from intraoperative X-rays images. These coordinates were represented in a three-dimensional stereotactic space and in the digitalized atlas of the human basal ganglia. RESULTS: HFS-STN resulted in significant improvement of motor function (62.8%) in off-medication state and levodopa-equivalent dose reduction of 68.7% (p < 0.05). Most of the active contacts (78.6%) were situated close to (+/- 1.6 mm) the dorsal border of the STN (STN-DB), while 16% were dorsal and 5.4% were ventral to it. Similar distribution was observed in the atlas. The euclidean distance between the STN-DB distribution center and the active contacts distribution center was 0.31 mm, while the distance between the active contacts distribution center and the stereotactic theoretical target was 2.15 mm. Most of the space defined by the active contacts distribution (53%) was inside that defined by the STN-DB distribution. CONCLUSION: In our series, most of the active electrodes were situated near the STN-DB. This suggests that HFS-STN could influence not only STN but also the dorsal adjacent structures (zona incerta and/or Fields of Forel).

[Gustatory disorders during multiple sclerosis relapse]. / Les troubles du goût au cours de poussées de sclérose en plaques.

Gustatory dysfunction is a known but uncommon element in the course of multiple sclerosis. Gustatory dysfunction has been described during the chronic progressive phase and during the relapse phase. We report five patients with clinically definite multiple sclerosis who developed transient gustatory disorders during the relapse phase of their disease. Agueusia occurred as one of the first symptoms in three patients, revealing the disease. Symptoms generally improved with remission or corticosteroid administration. These disorders are due to demyelinating lesions of the gustatory pathways in the thalamus or brainstem. MRI studies were not performed during the relapse phase and no clinical neuroimaging correlations could be established. Agueusia may be accompanied by olfactory dysfunction which is due to plaque demyelinization of the olfactory pathways, particularly in the temporal and inferior frontal lobes. Taste anomalies can also be observed in other diseases, including systemic diseases such as sarcoidosis or Sjogrën's syndrome. Drug-induced gustatory disorders are also reported.