Pushing the limits of the Leksell stereotactic frame for

0 downloads 0 Views 1MB Size Report
DOI 10.1007/s00701-016-2878-1. Pushing the limits of the Leksell stereotactic frame for spinal lesions up to C3: fixation at the maxilla. Manjul Tripathi, Narendra ...
Pushing the limits of the Leksell stereotactic frame for spinal lesions up to C3: fixation at the maxilla Manjul Tripathi, Narendra Kumar & Kanchan Kumar Mukherjee

Acta Neurochirurgica The European Journal of Neurosurgery ISSN 0001-6268 Acta Neurochir DOI 10.1007/s00701-016-2878-1

1 23

Your article is protected by copyright and all rights are held exclusively by SpringerVerlag Wien. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self-archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”.

1 23

Author's personal copy Acta Neurochir DOI 10.1007/s00701-016-2878-1

TECHNICAL NOTE - FUNCTIONAL

Pushing the limits of the Leksell stereotactic frame for spinal lesions up to C3: fixation at the maxilla Manjul Tripathi 1 & Narendra Kumar 2 & Kanchan Kumar Mukherjee 1

Received: 29 March 2016 / Accepted: 14 June 2016 # Springer-Verlag Wien 2016

Abstract Background Spinal radiosurgery is not considered in the domain of traditional Gamma Knife radiosurgery (GKRS) setup. The major obstacles in GKRS for upper cervical spine lesions remain in difficulty of frame fixation, avoiding collision and maintaining the integrity of the relative position of the lesion from image acquisition to treatment. Methodology The supraorbital margin remains the standard lowest fixation point for Leksell stereotactic frame. We describe fixation at the maxilla to target and treat upper cervical spine lesions (up to C3 vertebra) with measures to ensure cervical immobilisation and precision of the GKRS treatment. Results We have treated two patients at the upper cervical spine up to C3 vertebra by fixing anterior pillars of the Leksell stereotactic frame at the maxilla. To ensure cervical immobilisation and precision of treatment, the neck was immobilised with

Presentation at a conference Not presented anywhere Clinical trial registration number Not required * Kanchan Kumar Mukherjee [email protected] Manjul Tripathi [email protected] Narendra Kumar [email protected] 1

2

a Philadelphia collar. The relative position between the head and sternum with the couch from image acquisition to the radiation delivery was kept constant. Docking angle was kept neutral (90 degrees) throughout the treatment (from image acquisition to actual treatment). Conclusions The maxilla is a potential alternative for stereotactic frame fixation. Measures to ensure cervical immobilisation with lower-down frame position permits treatment of lesions as low as C3 vertebra. Keywords Gamma Knife . Radiosurgery . Maxilla . Cervical lesion . Intradural . Extramedullary

Introduction Conventionally, the foramen magnum is considered the lower limit for target location for Gamma Knife radiosurgery (GKRS) [1–3]. A few centres have shared their experience in treating upper cervical spine lesions (up to C3 level) using the Hamilton-Lulu frame, which cannot be used for GKRS in the current format [4, 5]. Absolute immobilisation is an integral component of GKRS, which directly influences the accuracy of the treatment. Since, a stereotactic frame is usually fixed above the supraorbital margin, it is not possible to target lesions beyond the C2 vertebra [2, 6]. We describe our experience with stereotactic frame fixation on the maxilla to target lesions up to the C3 vertebra with a protocol to maintain immobilisation of the upper cervical spine.

Department of Neurosurgery, Post Graduate Institute of Medical Education and Research, Neurosurgery Office, Nehru Hospital, 5th Floor, Chandigarh 160012, India

Materials and methods

Department of Radiotherapy, Post Graduate Institute of Medical Education and Research, Nehru Hospital, Ground Floor, Chandigarh 160012, India

We have treated two patients at the upper cervical spine with residual intradural extramedullary (IDEM) lesions with GKRS

Author's personal copy Acta Neurochir Fig. 1 Gamma Knife treatment for patients with cervical IDEM: first patient (a axial, b sagittal and c coronal images) and second patient (d axial, e sagittal and f coronal images)

using the Leksell Perfexion model (Elekta Instruments, Norcross, GA, USA) with Gamma Plan version 10. The first patient was a 48-year-old man, with residual C2-3 neurofibroma extending through intervertebral foramina (volume 4.13 cc). The second patient was a 32-year-old woman, with residual meningothelial meningioma extending from lower margin of C1 to the upper border of the C3 vertebra at left lateral border of the spinal cord (volume 2.75 cc) (Fig. 1) (Table 1). For cervical immobilisation, a Philadelphia collar (PC) was used. A Leksell stereotactic frame was fixed anteriorly in the outer table of the zygomatic process of the maxilla and posteriorly to the occipital bone (Fig. 2). During application of the frame, the skullcap, MR indicator frame, skull measurement frame and automated positioning system (APS) adapter were fixed to the frame to rule out any incompatibility or collision (Fig. 3). Radiological images were obtained with magnetic resonance imaging (MRI) with the head in neutral position. To minimise movement in the upper cervical spine, we measured the height of the skull (from glabella) and sternum (mid inspiration) to ground surface (in lying down on a flat couch). The difference between the glabellar-floor and sternal-floor distance was calculated. The difference was kept constant from image acquisition to GKRS treatment. The patient positioning system (PPS) was maintained at the abovementioned difference throughout the procedure. To avoid discomfort due to constant posture, intermittent breaks were given, along with 5 mg diazepam and 5 mg morphine before the start of the treatment. Both patients tolerated the procedure

well. In both the cases, the target was achieved with frame fixation at the maxilla. At 6 months of follow-up, there has not been any acute complication. However, this short-term result does not testify the accuracy and success of this approach in itself.

Discussion The fundamental argument against spinal radiosurgery is lack of immobilisation of the target. As a solution, there have been several attempts in the past including invasive spinal immobilisation by fixing a frame to the spinous processes of a patient in the prone position. Hamilton and co-workers [4, 7] reported a target accuracy of 2 mm in the transverse plane and