Robot-assisted transcerebellar stereotactic approach to the posterior fossa in pediatric patients: a technical note

PURPOSE

During the last decade, there has been renewed interest in stereotactic approaches to diffuse intrinsic pontine gliomas (DIPGs) in children, due to the development of new concepts in molecular biology and management, and subsequent need for tissue sampling. Stereotactic frame-based and robot-assisted techniques are associated with reduced target error and have been incorporated into standard practice at our institution.

METHODS

Four children (age 2-7 years) underwent a robot-assisted frame-based transcerebellar approach using the Leksell G frame coupled with Renishaw's neuromate® stereotactic robot. The procedures included 3 biopsies (two brainstem tumors and one cerebellar hemispheric lesion) and 1 depth electrode implantation into a low-grade tumor remnant (ganglioglioma) of the middle cerebellar peduncle causing drug-resistant epilepsy in a young girl. Targeting was based on MRI, and in one case, 18F-FET-PET was coregistered to MRI to improve sampling accuracy. The frame was applied 180° rotated compared to standard orientation, and patients were positioned prone during surgery and stereotactic preoperative CT scan. Postoperative CT scan ruled out complications and was coregistered to preoperative MRI to check the target accuracy.

RESULTS

No complications occurred, and targeting was accurate in all cases. All tissue samplings provided proper histology; depth electrode EEG exploration was diagnostic and led subsequent resective surgery.

CONCLUSIONS

According to our experience, the transcerebellar frame-based robotic stereotactic approach to the cerebellum and the brainstem is feasible, safe, and effective even in young children.

The stereotactic suboccipitaltranscerebellar approach to lesions of the brainstem and the cerebellum

OBJECTIVE

The stereotactic suboccipital-transcerebellar approach is widely regarded as technically demanding requiring substantial modifications of the standard stereotactic methods thus often making a transfrontal approach preferable. In this comprehensive series we aim to present our experience with the stereotactic suboccipital-transcerebellar approach to lesions of the brainstem or cerebellum using two standard stereotactic systems.

PATIENTS AND METHODS

In the period of 2000-2015 overall 80 patients (mean age 43.95 ± 23.76 years) with lesions of the brainstem or cerebellum underwent stereotactic surgery for diagnostic or therapeutic purposes via a suboccipital approach. In 59 patients stereotactic surgery was performed using the Riechert-Mundinger Stereotactic Frame, the Leksell Stereotactic Frame was used in 21 patients. For both frames standard systems were used without modification. Retrospective analysis of intraoperative stereotactic technique, achievement of the predefined surgical objectives and perioperative complications was carried out.

RESULTS

In this series, the stereotactic suboccipital-transcerebellar approach proved to be feasible with two standard stereotactic systems. Using either frame the predefined surgical objective was achieved in 90.0%. A verified neuropathological diagnosis was obtained in 89.6%. Minor transient perioperative complications occurred in 8.75%. There was no surgery-related permanent morbidity or mortality.

CONCLUSION

In this comprehensive series the stereotactic suboccipital-transcerebellar approach using a standard stereotactic system proved to be a favorable stereotactic approach with a high diagnostic success rate and no surgery-related permanent morbidity.

Novel Use of the Leksell Gamma Frame for Stereotactic Biopsy of Posterior Fossa Lesions

BACKGROUND

Stereotactic transcerebellar biopsies of brainstem tumors have often been reported. The Leksell frame or Cosman-Roberts-Wells frame is often used in transcerebellar approaches. However, to access lesions via the cerebellum, these frames should be secured as inferiorly on the cranium as possible, which can require exaggerated neck flexion and limit the flexible trajectory to the target. To overcome these disadvantages, we have devised a new way to use the Leksell frame for transcerebellar approaches.

METHODS

The frame was fixed to the upper part of the head and arc support by attaching the frame upside down, which gives surgeons a wide operative field and permits flexible trajectory planning.

RESULTS

Under local anesthesia, the surgery was performed in a sitting position. Air was observed in the target site on postoperative computed tomography and magnetic resonance imaging, which confirmed that a specimen had been successfully sampled from the site as planned.

CONCLUSIONS

Our devised transcerebellar approach provided a generous operative field and a flexible trajectory, which enabled minimally invasive biopsy of a posterior fossa lesions to be performed in a short amount of time with the patient under local anesthesia.