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Open access

“Open-window” craniectomy for the removal of frontal sinus mucosa to prevent a delayed mucocele: illustrative case

W. Caleb Rutledge, 1 2 MS, Ahmad Ozair, Javier E. Villanueva-Meyer, Brian Niehaus, and Michael W. McDermott

BACKGROUND

Frontal craniotomies for a medial subfrontal approach necessitate crossing the frontal sinus. Large superior extensions of the frontal sinus into frontal bone can result in mucosal retention in a free craniotomy bone flap, leading to a delayed mucocele with significant associated morbidity. The authors describe an “open-window” craniectomy technique that permits mucosal removal under direct vision and maintains the inner table on the bone flap’s inferior side, helping to seal off the sinus opening with a pericranial flap.

OBSERVATIONS

An illustrative case involving a medial right frontal craniotomy for a third ventricle mass in a patient with a large superior extension of the frontal sinus into frontal bone is presented. After creating a free frontal bone flap, the inner table was drilled out to the margins of the frontal sinus cavity and any remaining mucosa was cleared. A portion of the inner table above the bone flap’s inferior margin was left in place, resembling an open window when viewed from the inner table side. The remaining anterior and posterior wall of the flap inferiorly provided a matched surface for the opening into the remaining frontal sinus, which was covered by pericranium. Long-term follow-up indicated no major complications or delayed mucocele.

LESSONS

The open-window craniectomy technique can be considered for frontal sinus violations in patients with large superior frontal bone extension.

Open access

Brainstem anesthesia during awake craniotomy: illustrative case

Yun Chen, Mei Sun, Hongmin Bai, Ruixin Yang, and Huan He

BACKGROUND

Awake craniotomy (AC) is performed to remove the lesions near or in eloquent areas, during which the patients are alert and without any airway instrument. Apnea is a severe complication in AC. Here, the authors describe a case of sudden apnea induced by unexpected local anesthesia of the brainstem during AC.

OBSERVATIONS

A 42-year-old male underwent AC for a large, recurrent, bilateral frontal lobe mass and experienced transient apnea and loss of brainstem reflexes during the surgery. The patient recovered spontaneous breath rhythm just a few minutes after the removal of a lidocaine cotton pledget, which was found near the patient’s midbrain. Then the patient awoke and cooperated to finish the surgery.

LESSONS

The administration of a local anesthetic subdurally in AC is common but risky. The scouring action of cerebral spinal fluid can spread those agents and cause unexpected brainstem anesthesia. A lower concentration of the anesthetic and keeping away from the cistern can make it safer.

Open access

BRAF-mutated suprasellar glioblastoma mimicking craniopharyngioma: illustrative case

Bryan Zheng, Belinda Shao, Jennifer Mingrino, Jonathan Poggi, Richard S Dowd, Douglas C Anthony, John E Donahue, and Curtis E Doberstein

BACKGROUND

Suprasellar masses commonly include craniopharyngiomas and pituitary adenomas. Suprasellar glioblastoma is exceedingly rare with only a few prior case reports in the literature. Suprasellar glioblastoma can mimic craniopharyngioma or other more common suprasellar etiologies preoperatively.

OBSERVATIONS

A 65-year-old male with no significant history presented to the emergency department with a subacute decline in mental status. Work-up revealed a large suprasellar mass with extension to the right inferior medial frontal lobe and right lateral ventricle, associated with significant vasogenic edema. The patient underwent an interhemispheric transcallosal approach subtotal resection of the interventricular portion of the mass. Pathological analysis revealed glioblastoma, MGMT partially methylated, with a BRAF V600E mutation.

LESSONS

Malignant glioblastomas can mimic benign suprasellar masses and should remain on the differential for a diverse set of brain masses with a broad range of radiological and clinical features. For complex cases accessible from the ventricle where the pituitary complex cannot be confidently preserved via a transsphenoidal approach, an interhemispheric approach is also a practical initial surgical option. In addition to providing diagnostic value, molecular profiling may also reveal therapeutically significant gene alterations such as BRAF mutations.

Open access

The infundibulochiasmatic angle and the favorability of an endoscopic endonasal approach in type IV craniopharyngioma: illustrative case

Guilherme Finger, Maria Jose C Ruiz, Eman H Salem, Matthew D Marquardt, Kyle C Wu, Lucas P Carlstrom, Ricardo L Carrau, Luciano M Prevedello, and Daniel M Prevedello

BACKGROUND

Lesions located in the floor of the third ventricle are among the most difficult to access in neurosurgery. The neurovascular structures can limit transcranial exposure, whereas tumor extension into the third ventricle can limit visualization and access. The midline transsphenoidal route is an alternative approach to tumor invading the third ventricle if the tumor is localized at its anterior half and a working space between the optic apparatus and the pituitary infundibulum exists. The authors introduce the “infundibulochiasmatic angle,” a valuable measurement supporting the feasibility of the translamina terminalis endoscopic endonasal approach (EEA) for resection of type IV craniopharyngiomas.

OBSERVATIONS

Due to a favorable infundibulochiasmatic angle measurement on preoperative magnetic resonance imaging (MRI), an endoscopic endonasal transsellar transtubercular approach was performed to resect a type IV craniopharyngioma. At 2-month follow-up, the patient’s neurological exam was unremarkable, with improvement in bitemporal hemianopsia. Postoperative MRI confirmed gross-total tumor resection.

LESSONS

The infundibulochiasmatic angle is a radiological tool for evaluating the feasibility of EEA when resecting tumors in the anterior half of the third ventricle. Advantages include reduced brain retraction and excellent rates of resection, with minimal postoperative risks of cerebrospinal fluid leakage and permanent pituitary dysfunction.

Open access

Introducing next-generation transcranial surgery with the head-mounted 3D View Vision display in extracorporeal microsurgery: illustrative cases

Young Ju Kim, Hidehito Kimura, Hiroto Kajimoto, Tatsuya Mori, Masahiro Maeyama, Kazuhiro Tanaka, and Takashi Sasayama

BACKGROUND

Exoscopy in neurosurgery offers various advantages, including increased freedom of the viewing axis while the surgeon maintains a comfortable upright position. However, the optimal monitor positioning to avoid interference with surgical manipulation remains unresolved. Herein, the authors describe two cases in which a three-dimensional head-mounted display (3D-HMD) was introduced into a transcranial neurosurgical procedure using an exoscope.

OBSERVATIONS

Case 1 was a 50-year-old man who presented with recurrent epistaxis and was diagnosed with an olfactory neuroblastoma that extended from the nasal cavity to the anterior cranial base and infiltrated the right anterior cranial fossa. Case 2 was a 65-year-old man who presented with epistaxis and was diagnosed with a left-sided olfactory neuroblastoma. In both cases, en bloc tumor resection was successfully performed via a simultaneous exoscopic transcranial approach using a 3D-HMD and an endoscopic endonasal approach, eliminating the need to watch a large monitor beside the patient.

LESSONS

This is the first report of using a 3D-HMD in transcranial surgery. The 3D-HMD effectively addressed issues with the field of vision and concentration while preserving the effectiveness of traditional microscopic and exoscopic procedures when observed on a 3D monitor. Combining the 3D-HMD with an exoscope holds the potential to become a next-generation surgical approach.

Open access

Extra-axial cavernous malformations of the foramen magnum: illustrative cases

Bo-Han Yao, Da Li, Liang Wang, and Zhen Wu

BACKGROUND

Extra-axial cavernous malformations involving the foramen magnum are rare, and preoperative diagnosis becomes difficult when they mimic meningiomas.

OBSERVATIONS

The authors present 2 cases of extra-axial cavernous malformations involving the foramen magnum. Surgical removal of the lesions was performed via far lateral craniotomy. The authors investigate the disease and elaborate the differential diagnosis.

LESSONS

The authors recommend that extra-axial cavernous malformations should be considered in the differential diagnosis of lesions in the foramen magnum region. Intraoperative frozen sections are helpful to the diagnosis, and resection warranted a favorable long-term outcome.

Open access

Surgical management of metastatic Hürthle cell carcinoma to the skull base, cortex, and spine: illustrative case

N. U. Farrukh Hameed, Meagan M Hoppe, Ahmed Habib, Jeffrey Head, Regan Shanahan, Bradley A Gross, Sandra Narayanan, Georgios Zenonos, and Pascal Zinn

BACKGROUND

Hürthle cell carcinoma (HCC) is an unusual and aggressive variant of the follicular type of differentiated thyroid cancer (DTC), accounting for less than 3% of DTCs but posing the highest risk of metastasis. Brain metastases are uncommonly reported in the literature but pose a poor prognosis. The low rate of brain metastases from HCC coupled with ambiguous treatment protocols for the extracranial disease complicate successful disease management and definitive treatment strategy. The authors present the case of a patient with HCC metastasis to the skull base, cortex, and spine with recent tibial metastasis.

OBSERVATIONS

Despite the presence of metastasis to the cortex, skull base, and spine, the patient responded very well to radiation therapy, sellar mass resection, and cervical spine decompression and fixation and has made a remarkable recovery.

LESSONS

The authors’ multidisciplinary approach to the patient’s care, including a diverse team of specialists from oncology, neurosurgery, orthopedic surgery, radiology, endocrinology, and collaboration with clinical trial researchers, was fundamental to her successful outcome, demonstrating the utility of intersecting specialties in successful outcomes in neuro-oncological patient care.

Open access

Management of a challenging dura-embedded anterior inferior cerebellar artery loop during a retrosigmoid hearing-preserving vestibular schwannoma resection: microsurgical technique and operative video. Illustrative case

Jaime L. Martínez Santos, Robert C. Sterner, and Mustafa K. Başkaya

BACKGROUND

Anatomical variants of the anterior inferior cerebellar artery (AICA), such as an anomalous “AICA loop” embedded in the dura and bone of the subarcuate fossa, increase the complexity and risk of vestibular schwannoma resections. Classically, osseous penetrating AICA loops are the most challenging to mobilize, as the dura must be dissected and the surrounding petrous bone must be drilled to mobilize the AICA away from the surgical corridor and out of harm.

OBSERVATIONS

The authors present a rare case of a dura-embedded, osseous-penetrating AICA loop encountered during a hearing-preserving retrosigmoid approach in which they demonstrate safe and efficient microdissection and mobilization of the AICA loop without having to drill the surrounding bone.

LESSONS

Although preoperative recognition of potentially dangerous AICA loops has been challenging, thin-sliced petrous bone computed tomography scanning and high-quality magnetic resonance imaging can be useful in preoperative diagnosis. Furthermore, this report suggests that a retrosigmoid approach is superior, as it allows early intradural recognition and proximal vascular control and facilitates more versatile mobilization of AICA loops.

Open access

Rare clival localization of an eosinophilic granuloma: illustrative case

Martin E. Weidemeier, Steffen Fleck, Werner Hosemann, Silke Vogelgesang, Karoline Ehlert, Holger N. Lode, and Henry W. S. Schroeder

BACKGROUND

Eosinophilic granuloma (EG) belongs to the family of Langerhans cell histiocytosis (LCH) and is considered to be a benign disease typically found in children younger than 15 years of age. Here, the authors describe an EG of unusual localization and clinical presentation.

OBSERVATIONS

The authors report a 9-year-old girl with an EG presenting as an osteolytic lesion of the clivus. After transsphenoidal resection and histological confirmation, adjuvant chemotherapy was initiated. Presenting signs and symptoms were weight loss, episodic grimacing, and moderate ballism-like movements. After a follow-up-period of 32 months, the patient presented with a total resolution of initial symptoms and no further tumor growth.

LESSONS

Although these lesions are rare, one should consider EG as a differential diagnosis when confronted with osteolytic lesions of the clivus.

Open access

A silent corticotroph adenoma: making the case for a pars intermedia origin. Illustrative case

Mohammad Bilal Alsavaf, Kyle C. Wu, Guilherme Finger, Eman H. Salem, Maria Jose Castello Ruiz, Saniya S. Godil, Luma Ghalib, Ricardo L. Carrau, and Daniel M. Prevedello

BACKGROUND

Silent corticotroph adenomas (SCAs) are the only pituitary adenomas thought to originate from the pars intermedia. This case report presents the rare finding of a multimicrocystic corticotroph macroadenoma displacing the anterior and posterior lobes of the pituitary gland on magnetic resonance imaging (MRI). This finding supports the hypothesis that silent corticotroph adenomas may originate from the pars intermedia and should be considered in the differential for tumors arising from this location.

OBSERVATIONS

A 55-year-old man presented with an episode of confusion and blurred vision. MRI demonstrated separation of the anterior and posterior glands by a solid-cystic lesion located within the pars intermedia that superiorly displaced the optic chiasm. Endocrinologic evaluation was unremarkable. The differential diagnosis included pituitary adenoma, Rathke cleft cyst, and craniopharyngioma. The tumor was confirmed to be an SCA on pathology and was completely removed through the endoscopic endonasal transsphenoidal approach.

LESSONS

The case highlights the importance of preoperative screening for subclinical hypercortisolism for tumors arising from this location. Knowledge of a patient’s preoperative functional status is critical and dictates their postoperative biochemical assessment to determine remission. The case also illustrates surgical strategies for resecting pars intermedia lesions without injuring the gland.