This provides real time physiological confirmation of the target and is felt to be a very useful adjunct to current advanced brain imaging techniques and target localisation by many workers. 3, 7 Using microelectrodes, electrophysiological recording of the STN can be obtained during the operation. However, as this method does not take into account individual variations in STN location, direct visualisation of the STN on special MRI sequences is a suitable method for accurate localisation. This can be defined using stereotactic ventriculography or three dimensional magnetic resonance imaging (MRI).

10 The coordinates thus obtained are referenced to a line drawn from the anterior commissure (AC) to the posterior commissure (PC). One of the methods involves using an atlas of brain structures and pre-existing data obtained by workers with considerable experience in the field of STN stimulation. 7вЂ“ 9 Various methods have been used to localise the STN. The degree of clinical improvement achieved by deep brain stimulation (DBS) is largely dependent on the accuracy of lead placement. 3вЂ“ 5 The STN gained popularity as a potential target for treatment of ParkinsonвЂ™s disease in 1990 when Bergman et al 6 proved experimentally that a lesion in the motor part of the STN in a non-human primate model reversed the symptoms of ParkinsonвЂ™s disease. Since the pioneering work of Benabid et al 1 and Pollak et al 2 in 1993вЂ“1994, chronic high frequency stimulation of the subthalamic nucleus (STN) has become the preferred surgical treatment for medically refractory ParkinsonвЂ™s disease.

Our current stereotactic method of electrode placement is relatively accurate. Fewer tracks were required to define STN activity on the side operated first.

Individual variations exist in the location of the STN target. No postoperative MRI related complication was observed.Д¬onclusion: Both direct visualisation of the STN on MRI and intraoperative electrophysiological recording are important in defining the best target. The distance from the centre of the electrode artefact to the final target used after electrophysiological recording on the fused images was 0.48 mm, 0.69 mm, and 2.9 mm in the x, y, and z axes, respectively. The mean of the final target after electrophysiological correction was 11.7 mm lateral, 2.1 mm posterior, and 3.8 mm inferior to the mid-point. Fifty good electrophysiological recordings of the STN (average length 4.65 mm) were achieved and target point adjusted in 90% of lead placements. Results: Based on coordinate calculation and MRI localisation, the mean of the target was 11.5 mm lateral, 2.5 mm posterior and 4.1 mm inferior to the mid-point of the ACвЂ“PC line. We adjusted electrode positions for placement in the centre of the STN electrical activity and verified this on postoperative MRI in 16 cases, which were fused to the preoperative images to measure actual error in electrode placement in the three axes. Intraoperative microelectrode recording was used. Target planning was done by coordinate guidelines and visualising the STN on MRI and defined in relation to the mid-point of the ACвЂ“PC line. Patients and methods: We implanted 54 electrodes into the STN in 27 patients. Photek products support specialist applications in: Physics (high energy, particle, nuclear), defense industries (threat warning), physical chemistry, bioluminescence, space science, material and biological inspection.Objectives: To define the role of magnetic resonance imaging (MRI) and intraoperative electrophysiological recording in targeting the subthalamic nucleus (STN) in ParkinsonвЂ™s disease and to determine accuracy of electrode placement. Photek has particular expertise in the design and manufacture of large area image intensifiers, ultra-fast photomultiplier tubes (PMTs), UV detectors and advanced photon counting camera systems. We have a comprehensive range of products for most photon detection applications and work with our customers to design bespoke solutions where these are required. We manufacture Image Intensifiers, Solar Blind Detectors, Photomultipliers, Streak Tubes, Neutron Detection and Imaging Systems and a range of associated electronics and Camera Systems. Photek is a specialist manufacturer and global supplier of vacuum based tubes and camera systems for charged particle detection and imaging (photon, electron, and neutron).

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