Discrete changes in brain volume after deep brain stimulation in patients with Parkinson's disease.

OBJECTIVES: Deep brain stimulation (DBS), targeting the subthalamic nucleus (STN) and globus pallidus interna, is a surgical therapy with class 1 evidence for Parkinson's disease (PD). Bilateral DBS electrodes may be implanted within a single operation or in separate staged surgeries with an interval of time that varies patient by patient. In this study, we used the variation in the timing of implantation from the first to the second implantation allowing for examination of potential volumetric changes of the basal ganglia in patients with PD who underwent staged STN DBS. METHODS: Thirty-two patients with a mean time interval between implantations of 141.8 (±209.1; range: 7-700) days and mean duration of unilateral stimulation of 244.7 (±227.7; range: 20-672) days were included in this study. Using volumetric analysis of whole hemisphere and subcortical structures, we observed whether implantation or stimulation affected structural volume. RESULTS: We observed that DBS implantation, but not the duration of stimulation, induced a significant reduction of volume in the caudate, pallidum, putamen and thalamus ipsilateral to the implanted hemisphere. These findings were not dependent on the trajectory of the implanted electrode nor on first surgery pneumocephalus (0.07%: %Δ for intracranial volume between first and second surgery). In addition, unique regional atrophy differences were evident in each of the structures. CONCLUSION: Our results demonstrate that DBS implantation surgery may affect hemisphere volume at the level of subcortical structures connected to the surgical target.

A new extension to the Taste Strips test.

OBJECTIVE: Assessment of gustatory function in human subjects using the 'taste strips' test is an easy and validated procedure. The aim of this study was to extend this test in order to detect subjects with superior gustatory sensitivity. METHODS: The investigation included 134 subjects (29.5±12.6 years, range 18-84 years) with normal gustatory function. Four concentrations of sweet, sour, salty, and bitter were augmented with additional low concentrations (sweet: 25/12.5 mg/ml sucrose; sour: 27/15 mg/ml citric acid; salty: 6.4/2.6 mg/ml sodium chloride, bitter: 0.15/0.06 mg/ml quinine hydrochloride), resulting in a maximum extended taste score (ETS) of 24. RESULTS: The mean ETS was 14.5 ± 3.2. Specifically, it was 4.5 ± 1.2 for sweet, 2.8 ± 1.0 for sour, 4.0 ± 1.3 for salty, and 3.2 ± 1.2 for bitter. In contrast to the original version of the taste strips test, no ceiling effect was observed. Cluster analysis separated three groups of subjects by ETS, whereas test scores derived from the original four concentrations were insufficient to discriminate the subgroup with higher gustatory sensitivity. CONCLUSIONS: The extended taste strips test seems to be a useful tool for the detection of patients with low gustatory thresholds for sweet, sour, salty, or bitter taste.