Objectives: To define the role of magnetic resonance imaging (MRI) and intraoperative electrophysiological recording in targeting the subthalamic nucleus (STN) in Parkinson's disease and to determine accuracy of electrode placement. Patients and methods: We implanted 54 electrodes into the STN in 27 patients. Target planning was done by coordinate guidelines and visualising the STN on MRI and defined in relation to the mid-point of the AC-PC line. Intraoperative microelectrode recording was used. 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.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 AC-PC line. Fifty good electrophysiological recordings of the STN (average length 4.65 mm) were achieved and target point adjusted in 90% of lead placements. 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. 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. No postoperative MRI related complication was observed. Conclusion: Both direct visualisation of the STN on MRI and intraoperative electrophysiological recording are important in defining the best target. Individual variations exist in the location of the STN target. Fewer tracks were required to define STN activity on the side operated first. Our current stereotactic method of electrode placement is relatively accurate.
Intradural disc herniation is a well-recognized entity in the lumbar region, where over 90% of all intradural herniations are seen.1 By contrast, fewer than 5% occur in either the cervical or thoracic regions.1 We describe a case of a sudden onset neurological deficit caused by an intradural thoracic disc herniation at the T11-T12 level, the intradural nature of which was not diagnosed on preoperative MRI. To the best of our knowledge this is the first description of an intradural disc herniation at this level.
We present a case of multiple malignant melanoma metastases in the brain who is leading a normal life 16 years after the brain secondaries were managed by surgical resection, stereotactic radiation and chemotherapy. The primary lesion in the left upper arm was excised 4 years prior to the brain metastases. His most recent MRI shows him to be disease free. To the best of our knowledge, this is longest survival reported of any patient with multiple brain metastases from malignant melanoma.
A 43 year male patient presented with neck pain, upper limb paraesthesia and right foot weakness. A MRI scan revealed a bone cyst involving C4 spinous process, lamina, pedicles and the posterior part of the vertebral body causing focal spinal stenosis. A C4 laminectomy and C3-C5 lateral mass screw fixation was done. Intra-operatively the cyst was found to contain CSF with an associated dural defect. A CSF cervical vertebral cyst has not been previously reported in the literature. The clinical presentation, radiological features and management of this CSF vertebral cyst is discussed.
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