The bigger, the better? About the size of decompressive hemicraniectomies.

INTRODUCTION: Decompressive hemicraniectomy (DHC) is a treatment option in refractory ICP elevation and malignant infarction. A minimum diameter of 12 cm has been widely accepted as mandatory for effective decompression for ICP control. Complete hemispheric exposure is frequently advocated to further reduce the risk of parenchymal shear stress, hemorrhage and swelling. At the same time, superior efficacy and comparable risk profile of a more extensive decompression have yet to be established. MATERIAL AND METHODS: We reviewed 74 patients with comprehensive clinical data sets undergoing DHC from 2008 to 2013 at our institution. With a minimum threshold of 12 cm in AP diameter being observed in all cases, patients were grouped according to the absolute size of maximum AP diameter (<18 cm, ≥ 18 cm) and surface estimate (<180 cm(2), ≥ 180 cm(2)). Surgical technique, efficacy of ICP control, surgical complications and early clinical course were recorded. RESULTS: Baseline demographics were comparable in both groups. Surgery was effective in relieving or preventing intracranial hypertension in all patients, irrespective of craniectomy size. With smaller craniectomies, immediate surgical and secondary complications such as parenchymal herniation, hemorrhage, or swelling did not occur more frequently. CONCLUSION: Due to the heterogeneity of underlying disease, a conclusion as to effect of craniectomy size on long-term outcome cannot be made based on this study. However, if the obligatory lower threshold of 12 cm for DHC size and decompression to the temporal base are observed, a smaller craniectomy is equally effective in relieving intracranial hypertension. While not inadvertently associated with a more favorable surgical risk profile, it does not increase the risk for early secondary complications such as parenchymal shear stress, hemorrhage and swelling.

Virtual neuroendoscopy: MRI-based three-dimensional visualization of the cranial nerves in the posterior cranial fossa.

This article presents the advances of three-dimensional (3D) virtual neuroendoscopy of the cranial nerves (CN) in the posterior fossa. Interactive 3D visualizations were generated and the anatomical landmarks, such as the root entry/exit zones (REZ) and cisternal segments of the CN were evaluated. Twenty patients (M:F, 6:14) with trigeminal neuralgia (TN) underwent MRI constructive interference in steady state (MRI(CISS)) imaging and subsequent 3D visualization based on explicit segmentation of the MRI(CISS) data and interactive evaluation with direct volume rendering including implicit segmentation. The 3D topography of the interesting CN V-X were evaluated with interactive and virtual neuroendoscopy. The anatomical landmarks of the CN V-X could be visualized in all 20 cases (100%). The systematic application of virtual neuroendoscopy could be realized in all patients for the non-invasive observation of the CN without any technical difficulties. Interactive 3D visualization using explicit and implicit techniques for segmentation, and 3D direct volume rendering is demonstrated to successfully identify 3D neurovascular relations in patients with trigeminal neuralgia. It has the ability to provide a useful tool for surgeons in the pre- and intraoperative evaluation of such cases.

Neurovascular relationship at the trigeminal root entry zone in persistent idiopathic facial pain: findings from MRI 3D visualisation.

BACKGROUND: Patients with atypical neuralgia or atypical facial pain have been surgically treated with microvascular decompression (MVD) of the trigeminal root entry zone (TREZ). There are no data regarding the sensitivity and specificity of a vessel-TREZ relationship as a cause of pain in patients with persistent idiopathic facial pain (PIFP) according to the definition given by the International Headache Society (IHS). METHODS: The TREZ was visualised by 3D CISS MRI in 12 patients with unilateral PIFP according to the IHS criteria. RESULTS: The frequency of artery-TREZ, vein-TREZ, or vessel (artery/vein)-TREZ contacts on the symptomatic and asymptomatic sides did not differ significantly. On the symptomatic side, vessel-TREZ contact was found in 58% of patients (sensitivity). On the asymptomatic side, vessel-TREZ contact was absent in 33% of patients (specificity). CONCLUSIONS: On the basis of the low sensitivity and specificity found in the present study, PIFP cannot be attributed to a vessel-TREZ contact, and therefore, pain relief after MVD cannot be expected.