Letter to the Editor: Endoscope-assisted hemispherotomy and corpus callostomy

Free access

If the inline PDF is not rendering correctly, you can download the PDF file here.

TO THE EDITOR: We read the article by Sood et al.4 with interest (Sood S, Marupudi NI, Asano E, et al: Endoscopic corpus callosotomy and hemispherotomy. J Neurosurg Pediatr 16:681–686, December 2015).

We have are very happy to note that the concept of the technique (which has been described by us) of performing endoscopy-assisted hemispherotomy and corpus callostomy has been reproduced in this study, demonstrating its efficacy. However, we wish to point out certain things.

In Discussion, the authors state, “Since the submission of this paper, Chandra et al. have described their experience with endoscopic hemispherotomy.”4 We do not understand how the authors claim their originality on this technique when our paper was already published1 before their own paper (date of acceptance of our paper: January 4, 2015, vs date of acceptance of Sood et al.'s paper: May 11, 2015). Even the PubMed publication shows our paper to have been published April 2015, while Sood and colleagues' paper was published September 2015. We request that the authors acknowledge and correct this in the proper perspective. Following this paper, we also published a fairly large series on endoscopy-assisted corpus callosotomy with commisurotomy (n = 16) and then subsequently also a review article.2,3

The authors claim a variation of using a bimanual technique. We wish to state that, currently, we now have experience with performing more than 25 hemispherotomies using a free-hand technique. When we devised the procedure, we went through the learning curve of using a single port versus a bimanual technique and finally settled on a 2-handed technique of suction and bipolar with the endoscope held rigidly by a holder. We find this technique most suitable for all types of pathologies, including hemimegalencephaly and nonatrophic pathologies. A bimanual technique may be adequate for atrophic pathologies but becomes challenging for pathologies like hemimegalencephaly and Rasmussen's and cortical dysplasias. In our series of 25 cases, 15 cases belong to this category (Fig. 1). All of our procedures were performed using neuronavigation with the use of intraoperative MRI. Postoperative MRI in all cases confirmed a complete disconnection. We are now closely following up our cases and will publish on them after an adequate long-term follow-up. Currently, we are performing all our hemispherotomies using our described technique.

FIG. 1.
FIG. 1.

An endoscopic technique in a nonatrophic pathology. A 6-year-old boy presented with seizures that began when he was 2 years old. A and B: MR images showing evidence of large areas of cortical dysplasia in the frontal, insular, and parietal lobes with polymicrogyria on the left side. C: Magnetoencephalography (left) showed a tight cluster over the left (L) frontal lobe (red area). The child underwent an endoscope-assisted left-sided hemispherotomy. D–G: Postoperative MR images obtained on Day 6 showing the hemispheric disconnection. The track of access (D), disconnection at the level of the ventricles on axial section (E), disconnection as seen on the coronal section at the level of the temporal horn (F), and disconnection at the posterior part at the level of the thalamus (G) are shown. The MR images clearly show the efficacy of this technique where there is evidence of a clean hemispheric disconnection without any apparent damage to the surrounding area. In addition, it can be seen that the endoscopic technique has been used effectively even in a nonatrophic pathology. Figure is available in color online only.

We feel that the evolution of the endoscope-assisted hemispherotomy would be the same as that for pituitary surgery. This started with the initial use of use of endoscopy through cannulas. However over a period of time, the best method was found to be a free-hand technique, which provides much more flexibility and maneuverability. Having said this, it does depend a great deal on the surgeon's level of comfort.

Sood et al. thought that the size of the craniotomy would be larger with our described technique. The size of our craniotomy was the same as that described by them. Furthermore, we recommend that they, like us, should use the term “endoscope-assisted hemispherotomy” rather than endoscopic corpus callosotomy and hemispherotomy. “Endoscopic procedure” essentially refers to a surgical technique through a bur hole.

Finally, the authors stated that we use the sphenoid ridge and planum as landmarks. As stated in our paper in great detail, we use the junction of the genu with the caudate head as the landmark for the beginning of the anterior disconnection at the level of the anterior cerebral artery (ACA). Using this landmark, under neuronavigation, we proceed downward until we reach the posterior part of sphenoid ridge. Essentially, our internal landmark is also the ACA as later described by Sood et al.

While congratulating Sood et al. on performing the technique of endoscope-assisted hemispherotomy and corpus callosotomy, we wish to reiterate that this is not an original technique described by them, but it has helped the literature in changing the paradigms of management for this complex pathology.

References

  • 1

    Chandra PSKurwale NGarg ADwivedi RMalviya SVTripathi M: Endoscopy-assisted interhemispheric transcallosal hemispherotomy: preliminary description of a novel technique. Neurosurgery 76:4854952015

    • Search Google Scholar
    • Export Citation
  • 2

    Chandra SPKurwale NSChibber SSBanerji JDwivedi RGarg A: Endoscopic-assisted (through a mini craniotomy) corpus callosotomy combined with anterior, hippocampal, and posterior commissurotomy in Lennox-Gastaut syndrome: a pilot study to establish its safety and efficacy. Neurosurgery [epub ahead of print]2015

    • Search Google Scholar
    • Export Citation
  • 3

    Chandra SPTripathi M: Endoscopic epilepsy surgery: Emergence of a new procedure. Neurology India 63:5715822015

  • 4

    Sood SMarupudi NIAsano EHaridas AHam SD: Endoscopic corpus callosotomy and hemispherotomy. J Neurosurg Pediatr 16:6816862015

    • Search Google Scholar
    • Export Citation

Disclosures

The authors report no conflict of interest.

Keywords:

Response

We want to thank Drs. Chandra and Tripathi for their constructive comments. We would like to bring to their attention that our paper was originally submitted to Journal of Neurosurgery: Pediatrics in January 2015. We became aware of their work months after, when their paper was published online.1 Indeed, we added their paper to the reference list of our final article and stated that there were critical differences in the methodologies as highlighted in our paper and their letter. In this regard we feel we have appropriately cited and acknowledged their work. The evolution of our work was independent of theirs and is a continuation of our description of using an endoscope with mounted suction along the interhemispheric fissure for transcallosal resection of intraventricular and thalamic tumors.3

Both papers1 describe the application of an endoscope in somewhat different ways to perform a slight variation on vertical hemispherotomy originally described by Delalande et al.2 While Chandra et al. stated the use of a holder/assistant to hold and maneuver the endoscope,1 we have used a suction with the endoscope attached, which the surgeon can maneuver using his/her left hand to the required field of surgery and, at the same time, use the attached suction to bimanually perform the procedure. This is conceptually different from their method,1 which is traditionally used in transsphenoidal procedures, where the position of the endoscope does not need to be frequently changed since the field of surgery is small and is essentially the same as the field of vision through the endoscope. However, for hemispherotomy, where the field of surgery is far greater than the view through one position of the endoscope, frequent repositioning of the endoscope can be frustrating. Furthermore, it may result in crowding of instruments and necessitate a larger opening, as it appears to be on the coronal MRI submitted by Chandra et al. with their letter (Fig. 1G) and Fig. 7 of their article.1 Finally, with a fixed endoscope, reintroducing an instrument into the field is done blindly until it reaches beyond the tip of the endoscope where it can be seen. Alternatively, the endoscope has to be unmounted and remounted, which is somewhat tedious even with use of a robotic arm. We fully acknowledge that Chandra et al.1 have developed considerable experience with their technique. On the other hand, we have found the use of an endoscope with mounted suction far more convenient. In addition, the ability to follow the ACA laterally to the internal carotid artery bifurcation and middle cerebral artery, in continuity to the medially explored ACA, rather than identifying the sphenoid ridge on neuronavigation, seems more definitive and desirable to us. Over the past year, we have added another dimension to the procedure with the use of 3D Visionsense Endoscope (Visionsense Ltd.). The improved depth perception is a clear advantage over 2D and neuronavigation. Rather than using the traditional transverse incision used by Chandra et al.,1 we favor a vertical incision just lateral to the midline starting behind the hairline. The 3-cm incision allows us to perform a 2.5- to 3-cm craniotomy as seen in Figs. 1 and 4 of our article. This incision tends to be less painful and does not cause numbness from sectioning of supraorbital nerve branches as may occur in a traditional transverse incision.

Finally, the use of terms such as “minimally invasive surgery,” “endoscope-assisted surgery,” and “endoscopic surgery” as alluded to by Chandra et al. in their letter are somewhat confusing. To our knowledge, “minimally invasive surgery” does not truly describe how the surgery was done and appears most apt for spine surgery, where small incisions are used for instrumentation done under navigation guidance. The concept that “endoscopic surgery” needs to be done through a bur hole is antiquated. In our opinion, “endoscope-assisted surgery” refers to surgery primarily performed with a microscope while an endoscope is used intermittently during the procedure. Conversely, “endoscopic surgery” refers to the use of an endoscope as the major surgical tool; therefore, we prefer to refer to our procedure as such. In reality, since retractors are used during the procedure, one could also refer to it as retractor-assisted endoscopic surgery. This is really a question of semantics rather than scientific endeavor.

We would like to commend Chandra et al.1 for their effort in the development and improvement of their surgical techniques. It is heartening to see how similar ideas can develop in different institutions and how exchange of these ideas through publications further advances the field.

References

  • 1

    Chandra PSKurwale NGarg ADwivedi RMalviya SVTripathi M: Endoscopy-assisted interhemispheric transcallosal hemispherotomy: preliminary description of a novel technique. Neurosurgery 76:4854952015

    • Search Google Scholar
    • Export Citation
  • 2

    Delalande OBulteau CDellatolas GFohlen MJalin CBuret V: Vertical parasagittal hemispherotomy: surgical procedures and clinical long-term outcomes in a population of 83 children. Neurosurgery 60:2 Suppl 1ONS19ONS322007

    • Search Google Scholar
    • Export Citation
  • 3

    Sood SNundkumar NHam SD: Interhemispheric endoscopic resection of large intraventricular and thalamic tumors. J Neurosurg Pediatr 7:5965992011

    • Search Google Scholar
    • Export Citation

If the inline PDF is not rendering correctly, you can download the PDF file here.

Article Information

Contributor Notes

INCLUDE WHEN CITING Published online April 1, 2016; DOI: 10.3171/2015.12.PEDS15681.

© AANS, except where prohibited by US copyright law.

Headings
Figures
  • View in gallery

    An endoscopic technique in a nonatrophic pathology. A 6-year-old boy presented with seizures that began when he was 2 years old. A and B: MR images showing evidence of large areas of cortical dysplasia in the frontal, insular, and parietal lobes with polymicrogyria on the left side. C: Magnetoencephalography (left) showed a tight cluster over the left (L) frontal lobe (red area). The child underwent an endoscope-assisted left-sided hemispherotomy. D–G: Postoperative MR images obtained on Day 6 showing the hemispheric disconnection. The track of access (D), disconnection at the level of the ventricles on axial section (E), disconnection as seen on the coronal section at the level of the temporal horn (F), and disconnection at the posterior part at the level of the thalamus (G) are shown. The MR images clearly show the efficacy of this technique where there is evidence of a clean hemispheric disconnection without any apparent damage to the surrounding area. In addition, it can be seen that the endoscopic technique has been used effectively even in a nonatrophic pathology. Figure is available in color online only.

References
  • 1

    Chandra PSKurwale NGarg ADwivedi RMalviya SVTripathi M: Endoscopy-assisted interhemispheric transcallosal hemispherotomy: preliminary description of a novel technique. Neurosurgery 76:4854952015

    • Search Google Scholar
    • Export Citation
  • 2

    Chandra SPKurwale NSChibber SSBanerji JDwivedi RGarg A: Endoscopic-assisted (through a mini craniotomy) corpus callosotomy combined with anterior, hippocampal, and posterior commissurotomy in Lennox-Gastaut syndrome: a pilot study to establish its safety and efficacy. Neurosurgery [epub ahead of print]2015

    • Search Google Scholar
    • Export Citation
  • 3

    Chandra SPTripathi M: Endoscopic epilepsy surgery: Emergence of a new procedure. Neurology India 63:5715822015

  • 4

    Sood SMarupudi NIAsano EHaridas AHam SD: Endoscopic corpus callosotomy and hemispherotomy. J Neurosurg Pediatr 16:6816862015

    • Search Google Scholar
    • Export Citation
  • 1

    Chandra PSKurwale NGarg ADwivedi RMalviya SVTripathi M: Endoscopy-assisted interhemispheric transcallosal hemispherotomy: preliminary description of a novel technique. Neurosurgery 76:4854952015

    • Search Google Scholar
    • Export Citation
  • 2

    Delalande OBulteau CDellatolas GFohlen MJalin CBuret V: Vertical parasagittal hemispherotomy: surgical procedures and clinical long-term outcomes in a population of 83 children. Neurosurgery 60:2 Suppl 1ONS19ONS322007

    • Search Google Scholar
    • Export Citation
  • 3

    Sood SNundkumar NHam SD: Interhemispheric endoscopic resection of large intraventricular and thalamic tumors. J Neurosurg Pediatr 7:5965992011

    • Search Google Scholar
    • Export Citation
TrendMD
Cited By
Metrics

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 170 155 7
PDF Downloads 88 81 1
EPUB Downloads 0 0 0
PubMed
Google Scholar