The Brainstem Cavernoma Case Series: A Formula for Surgery and Surgical Technique.

Background and Objectives: Cavernous malformations (CM) are vascular malformations with low blood flow. The removal of brainstem CMs (BS) is associated with high surgical morbidity, and there is no general consensus on when to treat deep-seated BS CMs. The aim of this study is to compare the surgical outcomes of a series of deep-seated BS CMs with the surgical outcomes of a series of superficially located BS CMs operated on at the Department of Neurosurgery, College of Tuebingen, Germany. Materials and Methods: A retrospective evaluation was performed using patient charts, surgical video recordings, and outpatient examinations. Factors were identified in which surgical intervention was performed in cases of BS CMs. Preoperative radiological examinations included MRI and diffusion tensor imaging (DTI). For deep-seated BS CMs, a voxel-based 3D neuronavigation system and electrophysiological mapping of the brainstem surface were used. Results: A total of 34 consecutive patients with primary superficial (n = 20/58.8%) and deep-seated (n = 14/41.2%) brainstem cavernomas (BS CM) were enrolled in this comparative study. Complete removal was achieved in 31 patients (91.2%). Deep-seated BS CMs: The mean diameter was 14.7 mm (range: 8.3 to 27.7 mm). All but one of these lesions were completely removed. The median follow-up time was 5.8 years. Two patients (5.9%) developed new neurologic deficits after surgery. Superficial BS CMs: The median diameter was 14.9 mm (range: 7.2 to 27.3 mm). All but two of the superficial BS CMs could be completely removed. New permanent neurologic deficits were observed in two patients (5.9%) after surgery. The median follow-up time in this group was 3.6 years. Conclusions: The treatment of BS CMs remains complex. However, the results of this study demonstrate that with less invasive posterior fossa approaches, brainstem mapping, and neuronavigation combined with the use of a blunt "spinal cord" dissection technique, deep-seated BS CMs can be completely removed in selected cases, with good functional outcomes comparable to those of superficial BS CM.

Feasibility and accuracy of a voxel-based neuronavigation system with 3D image rendering in preoperative planning and as a learning tool for young neurosurgeons, exemplified by the anatomical localization of the superior sagittal sinus.

It is essential for a neurosurgeon to know individual anatomy and the corresponding anatomical landmarks before starting a surgery. Continuous training, especially of young neurosurgeons, is crucial for understanding complex neuroanatomy. In this study, we used a neuronavigation system with 3D volumetric image rendering to determine the anatomical relationship between the sagittal suture and the superior sagittal sinus (SSS) in patients with intracranial lesions. Furthermore, we discussed the applicability of such system in preoperative planning, residency training, and research. The study included 30 adult patients (18 female/12 male) who underwent a cranial computed tomography (CT) scan combined with venous angiography, for preoperative planning. The position of the sagittal suture in relation to the SSS was assessed in 3D CT images using an image guidance system (IGS) with 3D volumetric image rendering. Measurements were performed along the course of the sagittal sinus at the bregma, lambda, and in the middle between these two points. The SSS deviated to the right side of the sagittal suture in 50% of cases at the bregma, and in 46.7% at the midpoint and lambda. The SSS was displaced to the left of the sagittal suture in 10% of cases at the bregma and lambda and in 13% at the midpoint. IGSs with 3D volumetric image rendering enable simultaneous visualization of bony surfaces, soft tissue and vascular structures and interactive modulation of tissue transparency. They can be used in preoperative planning and intraoperative guidance to validate external landmarks and to determine anatomical relationships. In addition, 3D IGSs can be utilized for training of surgical residents and for research in anatomy.

Review of first clinical experiences with a 1.5 Tesla ceiling-mounted moveable intraoperative MRI system in Europe.

High-field intraoperative MRI (iMRI) systems provide excellent imaging quality and are used for resection control and update of image guidance systems in a number of centers. A ceiling-mounted intraoperative MRI system has several advantages compared to a conventional iMRI system. In this article, we report on first clinical experience with using such a state-of-the-art, the 1.5T iMRI system, in Europe. A total of 50 consecutive patients with intracranial tumors and vascular lesions were operated in the iMRI unit. We analyzed the patients' data, surgery preparation times, intraoperative scans, surgical time, and radicality of tumor removal. Patients' mean age was 46 years (range 8 to 77 years) and the median surgical procedure time was 5 hours (range 1 to 11 hours). The lesions included 6 low-grade gliomas, 8 grade III astrocytomas, 10 glioblastomas, 7 metastases, 7 pituitary adenomas, 2 cavernomas, 2 lymphomas, 1 cortical dysplasia, 3 aneurysms, 1 arterio-venous malformation and 1 extracranial-intracranial bypass, 1 clival chordoma, and 1 Chiari malformation. In the surgical treatment of tumor lesions, intraoperative imaging depicted tumor remnant in 29.7% of the cases, which led to a change in the intraoperative strategy. The mobile 1.5T iMRI system proved to be safe and allowed an optimal workflow in the iMRI unit. Due to the fact that the MRI scanner is moved into the operating room only for imaging, the working environment is comparable to a regular operating room.

Ultrasound-guided placement of ventricular catheters in first-time pediatric VP shunt surgery.

PURPOSE: Ventriculo-peritoneal (VP) shunts are effective for treatment of hydrocephalus in all age groups; however, they are associated with complications, a common one being ventricular catheter (VC) obstruction. VC position is likely to influence VC survival; however, most VCs are positioned freehand without guidance. This paper describes the accuracy of ultrasound guidance for VC placement and the impact of tip location on VC occlusion rate. METHODS: This is a retrospective cohort study of hydrocephalic children with first-time VP shunt and ultrasound-guided VC placement. Data recorded were age, sex, cause of hydrocephalus, side (left or right) and location (frontal or occipital) of VC, and exact postoperative position within the ventricle on first postoperative imaging: middle of ventricle (optimal position), near or touching the medial or lateral ventricle wall, within the third ventricle, and at the contralateral side. RESULTS: Of the 128 screened patients, 85 had a first postoperative imaging that clearly defined the VC position and were included. The follow-up was at least 12 months. Seventy-three percent of VCs were placed on the right and 71% via a frontal burhole. Eighty-three of 85 VC tips (95%) were in the intended ventricle, 61% at optimal position. Nine of 85 VCs (10%) obstructed within the first 12 months. Seven of nine (78%) obstructed VCs were located in a nonoptimal position (p = 0.016). Two of nine (22%) obstructed VCs entered through a frontal and seven of nine (78%) through an occipital burrhole (p = 0.016). CONCLUSION: Ultrasound-guided VC placement is as precise as frameless navigated placement. The optimal VC position was associated to a significant lower VC obstruction rate. The frontal position was superior to the occipital. Intraoperative US guidance is fast with almost no extra time and no extra cost. US-guided VC placement should become standard of care in VP shunt surgery.

Evaluation of the Predictive Value of Intraoperative Changes in Motor-Evoked Potentials of Caudal Cranial Nerves for the Postoperative Functional Outcome.

OBJECTIVE: The predictive value of changes in intraoperatively acquired motor-evoked potentials (MEPs) of the lower cranial nerves (LCN) IX-X (glossopharyngeal-vagus nerve) and CN XII (hypoglossal nerve) on operative outcomes was investigated. METHODS: MEPs of CN IX-X and CN XII were recorded intraoperatively in 63 patients undergoing surgery of the posterior cranial fossa. We correlated the changes of the MEPs with postoperative nerve function. RESULTS: For CN IX-X, we found a correlation between the amplitude of the MEP ratio and uvula deviation (P = 0.028) and the amplitude duration of the MEP and gag reflex function (P = 0.027). Patients with an MEP ratio of the glossopharyngeal-vagus amplitude ≤1.47 µV had a 3.4 times increased risk of developing a uvula deviation. Patients with a final MEP duration of the CN IX-X ≤11.6 milliseconds had a 3.6 times increased risk for their gag reflex to become extinct. CONCLUSIONS: Our study greatly contributes to the current knowledge of intraoperative MEPs as a predictor for postoperative cranial nerve function. We were able to extent previous findings on MEP values of the facial nerve on postoperative nerve function to 3 additional cranial nerves. Finding reliable predictors for postoperative nerve function is of great importance to the overall quality of life for a patient undergoing surgery of the posterior cranial fossa.

Congenital left temporal large arachnoid cyst causing intraorbital optic nerve damage in the second decade of life.

AIM: Intracranial sylvian arachnoid cysts are often asymptomatic lesions. We present a 16-year-old female patient with progressive loss of vision together with an unusual visual field defect on the left eye accompanied by headache. METHOD: A left frontotemporal sylvian arachnoid cyst was known since she was 9 months old, but observed ever since in the asymptomatic patient. Now, ophthalmological examination revealed bi-upper quadrant anopia on the left eye. Magnetic resonance imaging (MRI) and computed tomography showed erosion of the lateral orbital wall associated with intraorbital compression of the optic nerve by the cyst at the entrance into the optic canal. Microsurgical cyst fenestration to the basal cisterns was performed using a temporal mini-craniotomy. RESULT: Full improvement of vision and visual field defects was observed in the follow-up. On postoperative MRI, an increase of the tissue surrounding the optic nerve in the conus and better delineation at the entrance of optic canal was noted. CONCLUSION: Long-standing asymptomatic sylvian arachnoid cysts may suddenly produce severe unilateral visual deficits if the cyst erodes the lateral orbital wall. These deficits may rapidly revert to normal if surgical action is not delayed. If surveillance MRIs of sylvian arachnoid cysts show a narrowing of the conus diameter compared to the contralateral side, a yearly ophthalmological surveillance examination seems to be warranted in else wise asymptomatic patients.