Chronic implantation of newly developed suprachoroidal-transretinal stimulation prosthesis in dogs.

PURPOSE: To investigate the feasibility of implanting a newly developed suprachoroidal-transretinal stimulation (STS) prosthesis in dogs and to determine its biocompatibility and stability over a 3-month period. METHODS: The STS prosthesis system consisted of an array of 49 electrodes (nine were active), an intravitreal return electrode, and an extraocular microstimulator. The 49-electrode array was implanted into a scleral pocket of each of three healthy beagle dogs. Color fundus photography, fluorescein angiography, electroretinography, and functional testing of the STS system were performed postoperatively. The dogs were euthanatized 3 months after the implantation, and the retinas were evaluated histologically. RESULTS: All the prostheses were successfully implanted without complications, and no serious complications occurred during the 3-month postoperative period. The fixation of the implant was stable throughout the experimental period. Fluorescein angiography showed that the entire retina, including the area on the electrode array, remained well perfused without intraocular inflammation. Electroretinograms recorded from the eyes with the prosthesis did not differ significantly from those recorded from control eyes. Functional testing of the STS system showed that this system performed well for the 3-month experimental period. Histologic evaluations showed good preservation of the retina over the electrode array. CONCLUSIONS: Implantation of a newly developed STS retinal prosthesis into a scleral pocket of beagle dogs is surgically feasible and can be performed without significant damage to the retina or the animal. The biocompatibility and stability of the system were good for the 3-month observation period.

Long-term suppression of tremor by deep brain stimulation of the ventral intermediate nucleus of the thalamus combined with pallidotomy in hemiparkinsonian patients.

Deep brain stimulation (DBS) of the ventral intermediate nucleus of the thalamus (VIM) is a powerful surgical option in the treatment of tremor-predominant Parkinson's disease. However, its therapeutic efficacy depends on the tremor distribution. DBS is highly efficient in relief of distal appendicular tremor but not other types of tremor. Also, it is generally thought that DBS of the VIM has no significant beneficial effects on other motor symptoms of Parkinson's disease. We report two hemiparkinsonian patients, in whom unilateral VIM DBS combined with posteroventral pallidotomy produced long-lasting suppression of not only hand tremor, but also leg or jaw tremor and other motor symptoms.