The benefit of image guidance for the contralateral interhemispheric approach to the lateral ventricle

Image-guided surgery for meningioma

Image-guided surgery (IGS-neuronavigation) has revolutionized the field of neurosurgery over the past few decades. Although commonly used for the diagnosis and resection of intracranial gliomas and metastases, IGS is also useful for meningioma surgery, particularly for accessing deep tumors, creating an optimal craniotomy for superficial lesions, and for showing the location of critical neurovascular structures deep to the tumor in skull base surgery. An additional bonus in meningioma surgery is that so-called brain shift is minimal or nonexistent, allowing for ongoing accurate navigation during the surgical procedure.

Quantitative anatomical comparison of the ipsilateral and contralateral interhemispheric transcallosal approaches to the lateral ventricle

OBJECTIVE The best approach to deep-seated lateral and third ventricle lesions is a function of lesion characteristics, location, and relationship to the ventricles. The authors sought to examine and compare angles of attack and surgical freedom of anterior ipsilateral and contralateral interhemispheric transcallosal approaches to the frontal horn of the lateral ventricle using human cadaveric head dissections. Illustrative clinical experiences with a contralateral interhemispheric transcallosal approach and an anterior interhemispheric transcallosal transchoroidal approach are also related. METHODS Five formalin-fixed human cadaveric heads (10 sides) were examined microsurgically. CT and MRI scans obtained before dissection were uploaded and fused into the navigation system. The authors performed contralateral and ipsilateral transcallosal approaches to the lateral ventricle. Using the navigation system, they measured areas of exposure, surgical freedom, angles of attack, and angle of view to the surgical surface. Two clinical cases are described. RESULTS The exposed areas of the ipsilateral (mean [± SD] 313.8 ± 85.0 mm²) and contralateral (344 ± 87.73 mm²) interhemispheric approaches were not significantly different (p = 0.12). Surgical freedom and vertical angles of attack were significantly larger for the contralateral approach to the most midsuperior reachable point (p = 0.02 and p = 0.01, respectively) and to the posterosuperior (p = 0.02 and p = 0.04) and central (p = 0.04 and p = 0.02) regions of the lateral wall of the lateral ventricle. Surgical freedom and vertical angles of attack to central and anterior points on the floor of the lateral ventricle did not differ significantly with approach. The angle to the surface of the caudate head region was less steep for the contralateral (135.6° ± 15.6°) than for the ipsilateral (152.0° ± 13.6°) approach (p = 0.02). CONCLUSIONS The anterior contralateral interhemispheric transcallosal approach provided a more expansive exposure to the lower two-thirds of the lateral ventricle and striothalamocapsular region. In normal-sized ventricles, the foramen of Monro and the choroidal fissure were better visualized through the lateral ventricle ipsilateral to the craniotomy than through the contralateral approach.

Contralateral posterior interhemispheric approach to deep medial parietooccipital vascular malformations: surgical technique and results

OBJECTIVE Deep medial parietooccipital arteriovenous malformations (AVMs) and cerebral cavernous malformations (CCMs) are traditionally resected through an ipsilateral posterior interhemispheric approach (IPIA), which creates a deep, perpendicular perspective with limited access to the lateral margins of the lesion. The contralateral posterior interhemispheric approach (CPIA) flips the positioning, with the midline positioned horizontally for retraction due to gravity, but with the AVM on the upper side and the approach from the contralateral, lower side. The aim of this paper was to analyze whether the perpendicular angle of attack that is used in IPIA would convert to a parallel angle of attack with the CPIA, with less retraction, improved working angles, and no significant increase in risk. METHODS A retrospective review of pre- and postoperative clinical and radiographic data was performed in 8 patients who underwent a CPIA. RESULTS Three AVMs and 5 CCMs were resected using the CPIA, with an average nidus size of 2.3 cm and CCM diameter of 1.7 cm. All lesions were resected completely, as confirmed on postoperative catheter angiography or MRI. All patients had good neurological outcomes, with either stable or improved modified Rankin Scale scores at last follow-up. CONCLUSIONS The CPIA is a safe alternative approach to the IPIA for deep medial parietooccipital vascular malformations that extend 2 cm or more off the midline. Contralaterality and retraction due to gravity optimize the interhemispheric corridor, the surgical trajectory to the lesion, and the visualization of the lateral margin, without resection or retraction of adjacent normal cortex. Although the falx is a physical barrier to accessing the lesion, it stabilizes the ipsilateral hemisphere while gravity delivers the dissected lesion through the transfalcine window. Patient positioning, CSF drainage, venous preservation, and meticulous dissection of the deep margins are critical to the safety of this approach.

Intracranial Meningiomas: A 30-Year Experience and Literature Review

Intracranial meningiomas are tumors arising from the covering cells of the arachnoid layer of the dura mater or from the intraventricular choroid plexus. While mostly benign tumors, they still represent a major challenge to neurosurgeons and other medical disciplines involved in their diagnostic and therapeutic management. Although this review intends to give some state-of-the-art information from the literature, it is mainly based on personal experiences since more than 30 years caring for more than 1500 meningioma patients and point to a few new strategies to further improve on patient outcome.Diagnostics are based on magnetic resonance imaging which shows the relationship between tumor and surrounding intracranial structures, particularly the brain but also the vasculature and to some extent the cranial nerves. Furthermore, it may suggest the grading of the tumor and is very helpful in the postoperative diagnosis of complications and later follow-up course.Surgery still is the main treatment with the aim to completely remove the tumor; also in cases of recurrence, other additional options include radiotherapy and radiosurgery for incompletely removed or recurrent meningiomas. Postoperative chemotherapy has not been shown to provide substantial benefit to the patient especially in highly malignant meningiomas.All therapy options should be intended to provide the patient with the best possible functional outcome. Patients' perspective is not always equivalent to surgeons' perspectives. Neuropsychological evaluation and additional guidance of patients harboring meningiomas have proven to be important in modern neurosurgical intracranial tumor treatment. Their help beyond neurosurgical care facilitates the patients to lead an independent postoperative life.

Contralateral Interhemispheric Approach to Deep-Seated Cavernous Malformations

BACKGROUND:

Deep-seated periventricular cavernous malformations of the basal ganglia or thalamus can be approached via an interhemispheric craniotomy.

OBJECTIVE:

To determine surgical efficacy and clinical outcomes of the contralateral interhemispheric approach.

METHODS:

Retrospective chart review was performed on patients undergoing an interhemispheric approach for the resection of deep-seated cavernous malformation by the senior author (R.F.S.) between 2005 and 2013. Demographic data and clinical outcomes were reviewed. Pre- and postoperative imaging were analyzed for lesion location, size, associated venous anomaly, proximity to ventricle, and presence of residual.

RESULTS:

Twenty-one patients underwent a contralateral interhemispheric-transventricular approach, 7 patients had a contralateral interhemispheric-transcingulate approach and 3 patients had a contralateral interhemispheric-transchoroidal approach. Mean age was 40.1 years, and the majority were female (58.1%). Mean maximum cavernoma diameter was 1.97 cm, and 43.8% reached the surface of the ventricle. Average follow-up was 8.9 months, with complete resection achieved in 96.8% of patients. At last follow-up, 61.3% of patients remained stable and 29.0% had improved. Of the patients, 6.5% experienced transient weakness that resolved at last follow-up, and 1 patient (3.2%) had short-term memory problems. There were no surgical mortalities.

CONCLUSION:

The contralateral interhemispheric approach is a safe, clinically well tolerated, and surgically efficacious approach to deep-seated cavernomas.

Stand-alone 3D-ultrasound navigation after failure of conventional image guidance for deep-seated lesions

Image guidance has proven to be an important tool in surgery for deep-seated or eloquently located cavernomas. However, neuronavigation depending on preoperative images can fail. Thus, the displayed anatomy might be distorted already during the approach. This report demonstrates the use of three-dimensional intraoperative ultrasound (3D-US) as a rescue tool, when conventional navigation is erroneous. Two patients with symptomatic cavernomas, the one located subcortically in the right peritrigonum, the other in the left thalamus, were operated in our clinic via an image-guided approach. An integrated ultrasound-navigation system was used for neuronavigation. In both cases, navigation based on preoperative MRI failed after the craniotomy because patient-to-image registration was lost. In both cases, a simple registration of the patient's orientation was performed. Then a 3D-US volume was acquired and navigation was performed using the 3D-US data set. This is accurate as image acquisition and navigation are done in the same system. The cavernoma was visualized without difficulties in both cases. It could be reached directly via the ultrasound-guided approach. Patients' symptoms improved postoperatively and a complete resection could be documented. Two cavernomas were successfully resected using 3D-US guidance. In our experience, stand-alone 3D-US navigation is an effective option if conventional MRI-based navigation fails.

Neuroimaging and functional navigation as potential tools to reduce the incidence of surgical complications of lateral ventricular meningiomas

OBJECTIVE

Post-operative complications are common following treatment for meningiomas in the lateral ventricles because it is unavoidable to disrupt the integrity of the brain during surgery. This study discusses our experience with strategies for reducing these complications.

METHOD

Twenty-seven cases of lateral ventricular meningiomas treated surgically were summarized. The surgical corridors of 11 patients were selected according to the traditional anatomical markers. Navigation technologies including neuronavigation, ultrasonography, neuro-endoscopy, fMRI and intraoperative brain mapping were used in the other 16 patients. The post-operative Karnofsky Performance Status (KPS) of patients with or without navigation were compared at 1 week and 3, 6 and 12 months.

RESULTS

Except for one patient who died from postoperative intracerebral hemorrhage, most of the preoperative disorders improved after surgery. Although only 4 out of 27 cases suffered from permanent complications of visual field defect or epilepsy, novel postoperative complications were found in 8 of 11 patients without navigation but in only 5 of 16 patients with navigation. The post-operative KPS of patients with navigation were better than those without navigation at 1 week and 3 months after surgery.

CONCLUSION

The use of neuroimaging and functional navigation technologies may effectively lower the incidence of postoperative complications.