Endoscopic endonasal transclival approach for a ventral brainstem epidermoid cyst: illustrative case

Blake M. Hauser Department of Neurosurgery, Brigham and Women’s Hospital, Boston, Massachusetts; and

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Saksham Gupta Department of Neurosurgery, Brigham and Women’s Hospital, Boston, Massachusetts; and

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Tejas S. Athni Department of Neurosurgery, Brigham and Women’s Hospital, Boston, Massachusetts; and

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David J. Segar Department of Neurosurgery, Brigham and Women’s Hospital, Boston, Massachusetts; and

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Ravindra Uppaluri Department of Surgery, Division of Otolaryngology–Head and Neck Surgery, Brigham and Women’s Hospital, Dana Farber Cancer Center, Boston, Massachusetts

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Omar Arnaout Department of Neurosurgery, Brigham and Women’s Hospital, Boston, Massachusetts; and

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BACKGROUND

Intracranial epidermoid cysts are benign, slow-growing malformations that most commonly arise at the skull base. Maximizing resection of the cyst contents and the capsule reduces long-term recurrence but can be made difficult by cyst wall adherence to critical neurovascular structures. Expanded endonasal approaches (EEAs) offer an alternative to traditional open transcranial approaches for accessible epidermoid cysts. In this case report, the authors demonstrate a transclival EEA for a large, ventral brainstem epidermoid cyst.

OBSERVATIONS

A 41-year-old woman who presented with progressive headaches, diplopia, malaise, and fatigue was found to have a 4.7-cm midline, ventral brainstem epidermoid cyst. She underwent an expanded endonasal transclival approach that exposed the brainstem from the level of the dorsum sella to the tip of the basion. A near-total resection was completed with removal of all cyst contents and most of the capsular wall. Reconstruction was completed with Duragen, an autologous fat graft, and a nasoseptal flap. Postoperatively, she had a partial left cranial nerve VI palsy that remained stable 8 weeks after surgery.

LESSONS

The expanded endoscopic transclival approach can facilitate effective resection of midline, ventral epidermoid cysts.

ABBREVIATIONS

CSF = cerebrospinal fluid; EEA = expanded endonasal approach; MRI = magnetic resonance imaging

BACKGROUND

Intracranial epidermoid cysts are benign, slow-growing malformations that most commonly arise at the skull base. Maximizing resection of the cyst contents and the capsule reduces long-term recurrence but can be made difficult by cyst wall adherence to critical neurovascular structures. Expanded endonasal approaches (EEAs) offer an alternative to traditional open transcranial approaches for accessible epidermoid cysts. In this case report, the authors demonstrate a transclival EEA for a large, ventral brainstem epidermoid cyst.

OBSERVATIONS

A 41-year-old woman who presented with progressive headaches, diplopia, malaise, and fatigue was found to have a 4.7-cm midline, ventral brainstem epidermoid cyst. She underwent an expanded endonasal transclival approach that exposed the brainstem from the level of the dorsum sella to the tip of the basion. A near-total resection was completed with removal of all cyst contents and most of the capsular wall. Reconstruction was completed with Duragen, an autologous fat graft, and a nasoseptal flap. Postoperatively, she had a partial left cranial nerve VI palsy that remained stable 8 weeks after surgery.

LESSONS

The expanded endoscopic transclival approach can facilitate effective resection of midline, ventral epidermoid cysts.

ABBREVIATIONS

CSF = cerebrospinal fluid; EEA = expanded endonasal approach; MRI = magnetic resonance imaging

Intracranial epidermoid cysts arise from aberrant inclusions of remnant ectodermal tissue during development and are usually found in the cerebellopontine angle, fourth ventricle, and parasellar region.1,2 They are usually found off-midline.3,4 They may present with symptoms of mass effect or aseptic meningitis when they rupture. The location of the cyst and affected neurovascular structure dictates the approach, but regardless, achieving maximal resection of the cyst contents and capsule reduces long-term recurrence.5,6 Expanded endonasal approaches (EEAs) include the transclival approach to the ventral brainstem for pathologies, including cysts.7 This EEA may reduce approach-related morbidity, although it carries a high rate of postoperative cerebrospinal fluid (CSF) leak.8

Illustrative Case

A 41-year-old healthy woman presented with progressive morning tussive headaches, diplopia, malaise, and fatigue. She had an unremarkable neurological examination and was found to have a 4.7-cm T1-hypointense and nonenhancing T2-hyperintense and diffusion-restricting cyst on magnetic resonance imaging (MRI) concerning for a ventral brainstem epidermoid cyst (Fig. 1). Surgery was favored for her progressive symptoms. Given the midline nature of this cyst, an EEA through the transclival route was favored.

FIG. 1.
FIG. 1.

Preoperative MRI demonstrates a T1-hypointense and nonenhancing midline prepontine mass that displaces the basilar artery posteriorly (A). The mass is T2-hyperintense (B) and restricts diffusion on diffusion-weighted imaging (C) and the corresponding apparent diffusion coefficient sequence (D).

She underwent an EEA through the transclival corridor with neuro-monitoring of motor and somatosensory evoked potentials (Video 1). A left-sided nasoseptal flap was harvested and stored in the maxillary sinus, and the sphenoid sinus was opened widely, allowing exposure of the bilateral cavernous sinuses, planum sphenoidale, and clivus. The face of the sella was unroofed, and the inferior sellar wall and dorsum sellae were drilled. The thin upper clivus was drilled until dura was identified, and the remainder of the clivectomy was performed. The dura was incised and opened in an “I” shape, and the cyst contents were removed using bimanual dissection with a combination of multiple suctions and ring curette. The basilar artery, brainstem, and bilateral abducens nerves were identified. Then, a combination of blunt and sharp dissection was used to dissect and remove the cyst capsule off the brainstem. At the end of the resection, an angled endoscope was brought in to inspect the resection cavity up to the level of the basilar apex and down to the hypoglossal canals. Skull base reconstruction was completed with a dural matrix inlay, autologous fat graft, and nasoseptal flap. The flap was packed in place with NasoPore, Stryker. No lumbar drain was placed as it was felt that there was adequate coverage of the large skull base defect. The patient was found to have a partial unilateral abducens nerve palsy postoperatively but was otherwise neurologically intact. Postoperative MRI demonstrated near-total resection of the cyst (Fig. 2). She was monitored in the intensive care unit until postoperative day 3 and discharged home on postoperative day 5.

VIDEO 1. Clip showing a transclival EEA for a ventral brainstem epidermoid cyst. Key points include harvesting and preservation of the nasoseptal flap, a wide clival exposure, the use of blunt and sharp dissection of the cyst and its capsule wall off the brainstem and cranial nerves, and the reconstruction. Click here to view.

FIG. 2.
FIG. 2.

Postoperative MRI demonstrates near-total resection of the cyst, the presence of a T1-hyperintense fat graft (A), and a thin remnant of diffusion-restricting material (B). Postoperative computed tomography shows a wide corridor drilled through the clivus (C) from the dorsum sella to the tip of the basion (D).

She was seen in the clinic for outpatient follow-up on postoperative day 13. At that time, she had an improving partial cranial nerve VI palsy. She reported subjective relief of her preoperative symptoms and denied any ongoing headaches. Rigid nasal endoscopy showed a healing flap with expected crusting and no evidence of CSF leak. She remains clinically stable with a partial cranial nerve VI palsy 2 months postoperatively.

Discussion

Observations

Brainstem epidermoid cysts can be associated with significant symptoms of brainstem compression, and maximal safe removal of cyst contents and capsule wall is the mainstay of treatment. Brainstem epidermoid cysts may be treated with open approaches, including a transmastoid retrosigmoid approach, posterior petrosectomy with presigmoid approach, or combined petrosectomy with a presigmoid and middle fossa approach. These open approaches carry a high risk of associated morbidity and are still unlikely to yield entire cyst wall resection given the possibility of adherence to cranial nerves.6,9,10

In this case of a large midline ventral brainstem cyst, open approaches would require a long working corridor to the contralateral cyst components. Using a middle fossa, anterior petrosectomy approach does not allow access below Dorello’s canal and affords limited contralateral exposure. A transmastoid retrosigmoid approach likewise provides limited access to the contralateral side. A combined anterior and posterior petrosectomy would provide access to the contralateral cyst components and allow for bimanual dissection under a microscope, but this approach carries risk to the vestibulocochlear apparatus and the facial nerve, so was favored as a secondary approach option in case of recurrence. By contrast, the midline EEA offers the benefit of not needing to cross the plane of the cranial nerves to access the tumor, facilitating a maximal resection with reduced morbidity.6,9,10 There was no lumbar drain placed given what was felt to be an adequate skull base defect closure.

The EEA through the transclival corridor permits considerable visibility along the entirety of the ventral brainstem surface, ranging from the interpeduncular cistern to the foramen magnum.11 The transsphenoidal approach alone only allows access to the middle clival region. Unlocking the superior clivus requires drilling of the sellar floor and dorsum sellae, which facilitates pituitary transposition to maximize superior reach. Accessing the inferior clival region requires a dissection through the basopharyngeal fascia to drill inferiorly to the basion. Although not pursued in this case, skeletonization of the carotid arteries can improve lateral reach and also identify the abducens nerve by following the carotid sympathetic chain prior to cyst resection. The epidermoid cyst extended laterally to both abducens nerves, and dissection around and traction to this nerve may have contributed to the patient’s cranial nerve palsy.

Skull base reconstruction should be carefully considered prior to undertaking an EEA. A multilayered reconstruction, including an inlay and vascularized flap, is necessary to minimize risk of postoperative CSF leak.9 Further, a fat graft can reconstitute the clival defect and prevent pontine encephaloceles.12 It can be stored in the pharynx during the procedure, but as in this case, it can be stored in the maxillary sinus through a medial maxillary antrostomy to allow the inferior clivectomy.

The patient has not had any clinical evidence of CSF leak at 2 months since surgery, and she continues to experience significant relief from her presenting symptoms.

Lessons

Brainstem epidermoid cysts constitute a considerable operative challenge among skull base lesions. Utilizing an endoscopic endonasal approach to access the transclival corridor can provide sufficient operative exposure for a complete resection with limited associated morbidity, and concomitant use of multilayered skull base reconstruction including with vascularized tissue can help reduce the risk of postoperative CSF leak.

Acknowledgments

This work was funded by the National Institute of General Medical Sciences, National Institutes of Health, US Department of Health and Human Services (grant no. T32 GM144273, B.M.H., T.S.A).

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Arnaout, Hauser, Gupta, Segar. Acquisition of data: Arnaout, Gupta, Segar, Uppaluri. Analysis and interpretation of data: Arnaout, Hauser, Gupta, Athni, Uppaluri. Drafting of the article: Hauser, Gupta, Athni. Critically revising the article: all authors. Reviewed submitted version of the manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Arnaout. Statistical analysis: Hauser. Study supervision: Segar.

Supplemental Information

Videos

Video 1. https://vimeo.com/792261403.

References

  • 1

    Law EK, Lee RK, Ng AW, Siu DY, Ng HK. Atypical intracranial epidermoid cysts: rare anomalies with unique radiological features. Case Rep Radiol. 2015;2015:528632.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Kurosaki K, Hayashi N, Hamada H, Hori E, Kurimoto M, Endo S. Multiple epidermoid cysts located in the pineal and extracranial regions treated by neuroendoscopy. Neurol Med Chir (Tokyo). 2005;45(4):216219.

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  • 3

    Cambruzzi E, Presa K, Silveira LC, Perondi GE. Epidermoid cyst of the posterior fossa: a case report. J Bras Patol Med Lab. 2011;47(1):7982.

  • 4

    Patibandla MR, Yerramneni VK, Mudumba VS, Manisha N, Addagada GC. Brainstem epidermoid cyst: an update. Asian J Neurosurg. 2016;11(3):194200.

  • 5

    Aboud E, Abolfotoh M, Pravdenkova S, Gokoglu A, Gokden M, Al-Mefty O. Giant intracranial epidermoids: is total removal feasible? J Neurosurg. 2015;122(4):743756.

    • PubMed
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    • Export Citation
  • 6

    Fraser JF, Nyquist GG, Moore N, Anand VK, Schwartz TH. Endoscopic endonasal minimal access approach to the clivus: case series and technical nuances. Neurosurgery. 2010;67(3 Suppl):150158.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 7

    Prevedello DM, Fernandez-Miranda JC, Gardner P, et al. The transclival endoscopic endonasal approach (EEA) for prepontine neuroenteric cysts: report of two cases. Acta Neurochir (Wien). 2010;152(7):12231229.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Kamat A, Lee JY, Goldstein GH, et al. Reconstructive challenges in the extended endoscopic transclival approach. J Laryngol Otol. 2015;129(5):468472.

  • 9

    Forbes JA, Banu M, Lehner K, et al. Endoscopic endonasal resection of epidermoid cysts involving the ventral cranial base. J Neurosurg. 2019;130(5):15991608.

  • 10

    Vaz-Guimaraes F, Koutourousiou M, de Almeida JR, et al. Endoscopic endonasal surgery for epidermoid and dermoid cysts: a 10-year experience. J Neurosurg. 2019;130(2):368378.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    de Divitiis E, Esposito F, Cappabianca P, Cavallo LM, de Divitiis O. Extended endoscopic endonasal Transsphenoidal Approach to Supra-parasellar Tumors. Dolenc VV, Rogers L, eds. Cavernous Sinus: Developments and Future Perspectives. Springer Vienna; 2009:7586.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Koutourousiou M, Filho FV, Costacou T, et al. Pontine encephalocele and abnormalities of the posterior fossa following transclival endoscopic endonasal surgery. J Neurosurg. 2014;121(2):359366.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • Collapse
  • Expand
  • FIG. 1.

    Preoperative MRI demonstrates a T1-hypointense and nonenhancing midline prepontine mass that displaces the basilar artery posteriorly (A). The mass is T2-hyperintense (B) and restricts diffusion on diffusion-weighted imaging (C) and the corresponding apparent diffusion coefficient sequence (D).

  • FIG. 2.

    Postoperative MRI demonstrates near-total resection of the cyst, the presence of a T1-hyperintense fat graft (A), and a thin remnant of diffusion-restricting material (B). Postoperative computed tomography shows a wide corridor drilled through the clivus (C) from the dorsum sella to the tip of the basion (D).

  • 1

    Law EK, Lee RK, Ng AW, Siu DY, Ng HK. Atypical intracranial epidermoid cysts: rare anomalies with unique radiological features. Case Rep Radiol. 2015;2015:528632.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 2

    Kurosaki K, Hayashi N, Hamada H, Hori E, Kurimoto M, Endo S. Multiple epidermoid cysts located in the pineal and extracranial regions treated by neuroendoscopy. Neurol Med Chir (Tokyo). 2005;45(4):216219.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 3

    Cambruzzi E, Presa K, Silveira LC, Perondi GE. Epidermoid cyst of the posterior fossa: a case report. J Bras Patol Med Lab. 2011;47(1):7982.

  • 4

    Patibandla MR, Yerramneni VK, Mudumba VS, Manisha N, Addagada GC. Brainstem epidermoid cyst: an update. Asian J Neurosurg. 2016;11(3):194200.

  • 5

    Aboud E, Abolfotoh M, Pravdenkova S, Gokoglu A, Gokden M, Al-Mefty O. Giant intracranial epidermoids: is total removal feasible? J Neurosurg. 2015;122(4):743756.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Fraser JF, Nyquist GG, Moore N, Anand VK, Schwartz TH. Endoscopic endonasal minimal access approach to the clivus: case series and technical nuances. Neurosurgery. 2010;67(3 Suppl):150158.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 7

    Prevedello DM, Fernandez-Miranda JC, Gardner P, et al. The transclival endoscopic endonasal approach (EEA) for prepontine neuroenteric cysts: report of two cases. Acta Neurochir (Wien). 2010;152(7):12231229.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Kamat A, Lee JY, Goldstein GH, et al. Reconstructive challenges in the extended endoscopic transclival approach. J Laryngol Otol. 2015;129(5):468472.

  • 9

    Forbes JA, Banu M, Lehner K, et al. Endoscopic endonasal resection of epidermoid cysts involving the ventral cranial base. J Neurosurg. 2019;130(5):15991608.

  • 10

    Vaz-Guimaraes F, Koutourousiou M, de Almeida JR, et al. Endoscopic endonasal surgery for epidermoid and dermoid cysts: a 10-year experience. J Neurosurg. 2019;130(2):368378.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    de Divitiis E, Esposito F, Cappabianca P, Cavallo LM, de Divitiis O. Extended endoscopic endonasal Transsphenoidal Approach to Supra-parasellar Tumors. Dolenc VV, Rogers L, eds. Cavernous Sinus: Developments and Future Perspectives. Springer Vienna; 2009:7586.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Koutourousiou M, Filho FV, Costacou T, et al. Pontine encephalocele and abnormalities of the posterior fossa following transclival endoscopic endonasal surgery. J Neurosurg. 2014;121(2):359366.

    • PubMed
    • Search Google Scholar
    • Export Citation

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