Progress in neurological surgery
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Neuromodulation practitioners increasingly recognize the potential for peripheral nerve field stimulation (PNfS) to treat pain originating from the trunk. Conditions resulting in truncal pain that may respond to PNfS include cervical and lumbar postlaminectomy syndrome, inguinal neurapraxia, post-herpetic neuralgia, and post-thoracotomy pain. The focus of this chapter is to review the mechanism of action in PNfS, patient selection factors, programming strategies, and technical considerations.
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Although commonly used in clinical practice, peripheral nerve stimulation (PNS) for treatment of chronic pain is performed mainly with devices developed and marketed for spinal cord stimulation applications. This may be one of the reasons why PNS approach is marked by a very high complication rate, as the anatomy of peripheral nerves and the surrounding soft tissues is quite different from epidural spinal space for which the current devices are designed. ⋯ Based on the literature data and the analysis of the author's experience with PNS procedures it appears that although the rate of complications is relatively high, the morbidity associated with PNS approach is very minor and most problems may be resolved with simple re-operations, usually on outpatient basis. The reduction in complication rate is expected to occur when the hardware used in PNS procedures is appropriately adapted for PNS applications.
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The purpose of this study was to analyze tumor control and possible complications of gamma knife radiosurgery (GKRS) in patients with vestibular schwannomas using low marginal doses and conformal multiple shots to fit irregular tumor shapes. The authors evaluated 152 patients with more than 5 years of follow-up. Marginal doses were 9-15 Gy (median 12 Gy), with corresponding treatment volumes ranging from 0.1 to 18.7 cm3 (median 2.0 cm3). ⋯ Hydrocephalus was recognized in 5.3% of all patients, and tended to occur in cases with larger tumors (p = 0.0024). GKRS provides a safe and effective therapy for small to medium-sized tumors. However, indications for larger tumors must be carefully considered, as they are more difficult to control and liable to produce ataxia due to transient expansion.
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Gamma knife (GK) thalamotomy for functional disorders, primarily Parkinson disease and central pain, are described herein. The goal was to extend our present indications for selective thalamotomy. Our target for tremor surgery is about 45% of the thalamic length. ⋯ In most of our cases, the protocol was 130 Gy, delivered in one shot with a 4-mm collimator. The time courses of thalamic lesion changes and clinical improvement after irradiation were assessed. Thus, despite thalamic reaction changes being variable, we achieved a clinical success rate of approximately 80% with negligible complications.
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Radiosurgery is a minimally invasive technique designed to elicit a specific radiobiologic response at the target tissue using focused ionizing radiation delivered in single procedure. Radiosurgery was originally devised to treat intracranial lesions by delivering a high dose of radiation precisely at the intracranial target using stereotactic guidance. The term was coined and the field defined by Lars Leksell, a visionary leader of neurosurgery at the Karolinska Institute in Stockholm. ⋯ The long-term results of radiosurgery are now available and have established it as an effective noninvasive management strategy for many brain disorders. Radiosurgery is now considered a mainstream neurosurgical modality for treatment of vascular malformations, tumors, trigeminal neuralgia, movement disorders, and perhaps epilepsy. Its role as a tool for spine and body surgery is also under evaluation.