Application of electromagnetic technology to neuronavigation: A revolution in image-guided neurosurgery: Technical note
ABSTRACT The authors investigated the practicality of electromagnetic neuronavigation in routine clinical use, and determined the applications for which it is at the advantage compared with other systems.
A magnetic field is generated encompassing the surgical volume. Devices containing miniaturized coils can be located within the field. The authors report on their experience in 150 cases performed with this technology.
Electromagnetic neuronavigation was performed in 44 endoscopies, 42 ventriculoperitoneal shunt insertions for slit ventricles, 21 routine shunt insertions, 6 complex shunt insertions, 14 external ventricular drain placements for traumatic brain injury, 5 awake craniotomies, 5 Ommaya reservoir placements, and for 13 other indications. Satisfactory positioning of ventricular catheters was achieved in all cases. No particular changes to the operating theater set-up were required, and no significant interference from ferromagnetic instruments was experienced. Neurophysiological monitoring was not affected, nor did it affect electromagnetic guidance.
Neuronavigation enables safe, accurate surgery, and may ultimately reduce complications and improve outcome. Electromagnetic technology allows frameless, pinless, image-guided surgery, and can be used in all procedures for which neuronavigation is appropriate. This technology was found to be particularly advantageous compared with other technologies in cases in which freedom of head movement was helpful. Electromagnetic neuronavigation was therefore well suited to CSF diversion procedures, awake craniotomies, and cases in which rigid head fixation was undesirable, such as in neonates. This technology extends the application of neuronavigation to routine shunt placement and ventricular catheter placement in patients with traumatic brain injury.
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ABSTRACT: External ventricular drain (EVD) placement is standard of care in the management of aneurysmal subarachnoid haemorrhage-associated hydrocephalus (aSAH). However, there are no guidelines for EVD placement and management after aSAH. Optimal EVD insertion conditions, techniques to reduce the risk of EVD-associated infection and aneurysmal rebleeding, and methods of EVD removal are critical, yet incompletely answered management variables. The present literature consists primarily of small studies with heterogeneous populations and variable outcome measures, and suggests the following: EVDs may increase the risk of rebleeding; EVDs are increasingly placed by non-neurosurgeons with unclear results; intraparenchymal ICP monitors may be safely considered (with or without spinal drainage) in the setting of difficult EVD placement; the optimal timing and manner of EVD removal has yet to be defined; and the efficacy of prophylactic systemic antibiotics and antibiotic-coated EVDs needs further investigation. Nevertheless, there are no definitive practice guidelines for EVD placement and management techniques in aSAH patients. Large prospective randomised trials are needed to definitively address important gaps in our understanding of EVD management principles in the neurocritical care setting.British Journal of Neurosurgery 12/2010; 24(6):625-32. DOI:10.3109/02688697.2010.505989 · 0.95 Impact Factor
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ABSTRACT: As many as 40% of shunts fail in the first year, mainly due to proximal obstruction. The role of catheter position on failure rates has not been clearly demonstrated. The authors conducted a prospective cohort study of navigated shunt placement compared with standard blind shunt placement at 3 European centers to assess the effect on shunt failure rates. All adult and pediatric patients undergoing de novo ventriculoperitoneal shunt placement were included (patients with slit ventricles were excluded). The first cohort underwent standard shunt placement using anatomical landmarks. All centers subsequently adopted electromagnetic (EM) navigation for routine shunt placements, forming the second cohort. Catheter position was graded on postoperative CT in both groups using a 3-point scale developed for this study: (1) optimal position free-floating in CSF; (2) touching choroid or ventricular wall; or (3) intraparenchymal. Episodes and type of shunt revision were recorded. Early shunt failure was defined as that occurring within 30 days of surgery. Patients with shunts were followed-up for 12 months in the standard group, for a median of 6 months in the EM-navigated group, or until shunt failure. A total of 75 patients were included in the study, 41 with standard shunts and 34 with EM-navigated shunts. Seventy-four percent of navigated shunts were Grade 1 compared with 37% of the standard shunts (p=0.001, chi-square test). There were no Grade 3 placements in the navigated group, but 8 in the standard group, and 75% of these failed. Early shunt failure occurred in 9 patients in the standard group and in 2 in the navigated group, reducing the early revision rate from 22 to 5.9% (p=0.048, Fisher exact test). Early shunt failures were due to proximal obstruction in 78% of standard shunts (7 of 9) and in 50% of EM-navigated shunts (1 of 2). Noninvasive EM image guidance in shunt surgery reduces poor shunt placement, resulting in a significant decrease in the early shunt revision rate.Journal of Neurosurgery 12/2010; 113(6):1273-8. DOI:10.3171/2010.3.JNS091237 · 3.15 Impact Factor
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ABSTRACT: Catastrophic epileptic encephalopathies in children comprise devastating conditions that features cerebral dysfunction in association with refractory epileptic seizures. The diagnosis is based on the clinical findings, on magnetic resonance imaging (MRI) of the brain and on electroencephalographic findings. For these conditions, surgery remains essential for attaining seizure control. We report two cases of 5-year-old girls. The first one had a diagnosis of Rasmussens syndrome. The second one had a large porencephalic cyst secondary to perinatal cerebral ischemia. Despite trials of anticonvulsants, both patients deteriorated, and a functional hemispherectomy guided by neuronavigation was indicated and performed, with low morbidity and excellent seizure control. The neuronavigation proved to be a valuable guidance tool in performing the functional hemispherectomy, making the disconnections more accurate, and thus decreasing the surgical time and blood loss.Journal of Epilepsy and Clinical Neurophysiology 12/2010; 17(3):93-99. DOI:10.1590/S1676-26492011000300004