Endoscopic endonasal approach for resection of odontoid process, decompression of the cervicomedullary junction spinal cord, and resection of pannus.

Odontoid pannus is an abnormal collection of degenerative or inflammatory tissue on the C1-dens joint that can result in severe spinal cord compression myelopathy. Treatment options vary depending on severity and etiology. In cases of severe cord compression, surgical management could be either through a purely posterior approach or in combination with an anterior decompression via endoscopic endonasal approach (EEA). This case presents a 77-year-old female who underwent posterior cervical fixation for odontoid pannus causing dramatic cervical myelopathy who failed to improve over a 6-month period and required anterior transodontoid pannus resection and decompression via EEA. The video can be found here: https://stream.cadmore.media/r10.3171/2024.1.FOCVID23176.

Exoscope-based supracerebellar infratentorial approach for a pineal meningioma in the prone position.

The supracerebellar infratentorial (SCIT) approach is a well-described corridor to lesions in the quadrigeminal cistern, pineal gland, and dorsal midbrain. It can be performed in the prone or sitting position. The sitting position offers the benefit of gravity retraction of the cerebellum but comes at the expense of nonergonomic hand positioning and the potential risk of air embolism. The 3D exoscope is an alternative to the operating microscope and permits the SCIT approach in the prone position with excellent visualization. This video demonstrates exoscope-based SCIT approach for resection of a pineal meningioma in the prone position. The video can be found here: https://stream.cadmore.media/r10.3171/2023.10.FOCVID23155.

The endoscopic anterior transmaxillary temporal pole approach for mesial temporal lobe epilepsies: a feasibility study.

OBJECTIVE: In mesial temporal lobe epilepsy (MTLE), the ideal surgical approach to achieve seizure freedom and minimize morbidity is an unsolved question. Selective approaches to mesial temporal structures often result in suboptimal seizure outcomes. The authors report the results of a pilot study intended to evaluate the clinical feasibility of using an endoscopic anterior transmaxillary (eATM) approach for minimally invasive management of MTLEs. METHODS: The study is a prospectively collected case series of four consecutive patients who underwent the eATM approach for the treatment of MTLE and were followed for a minimum of 12 months. All participants underwent an epilepsy workup and surgical care at a tertiary referral comprehensive epilepsy center and had medically refractory epilepsy. The noninvasive evaluations and intracranial recordings of these patients confirmed the presence of anatomically restricted epileptogenic zones located in the mesial temporal structures. Data on seizure freedom at 1 year, neuropsychological outcomes, diffusion tractography, and adverse events were collected and analyzed. RESULTS: By applying the eATM technique and approaching the far anterior temporal lobe regions, mesial-basal resections of the temporal polar areas and mesial temporal structures were successfully achieved in all patients (2 with left-sided approaches, 2 with right-sided approaches). No neurological complications or neuropsychological declines were observed. All 4 patients achieved Engel class Ia outcome up to the end of the follow-up period (19, 15, 14, and 12 months). One patient developed hypoesthesia in the left V2 distribution but there were no other adverse events. The low degree of white matter injury from the eATM approach was analyzed using high-definition fiber tractography in 1 patient as a putative mechanism for preserving neuropsychological function. CONCLUSIONS: The described series demonstrates the feasibility and potential safety profile of a novel approach for medically refractory MTLE. The study affirms the feasibility of performing efficacious mesial temporal lobe resections through an eATM approach.

Differential tractography as a dynamic imaging biomarker: A methodological pilot study for Huntington's disease.

Huntington's disease (HD) is a neurodegenerative disorder characterized by motor, psychiatric, and cognitive symptoms. Due to its diverse manifestations, the scientific community has long recognized the need for sensitive, objective, individualized, and dynamic disease assessment tools. We examined the feasibility of Differential Tractography as a biomarker to evaluate correlation of symptom severity and of HD progression at the individual level. Differential tractography is a novel tractography modality that maps pathways with axonal injury characterized by a decrease of anisotropic diffusion pattern. We recruited sixteen patients scanned at 0-, 6-, and 12-month intervals by diffusion MRI scans for differential tractography assessment and correlated its volumetric findings with the Unified Huntington's Disease Rating Scale (UHDRS). Deterministic fiber tracking algorithm was applied. Longitudinal data was modeled using the generalized estimating equation (GEE) model and correlated with UHDRS scores, in addition to Spearman correlation for cross-sectional data. Our results show that volumes of affected pathways revealed by differential tractography significantly correlated with UHDRS scores in longitudinal data (p-value < 0.001), and chronological changes in differential tractography also correlated with the changes in UHDRS (p-value < 0.001). This technique opens new clinical avenues as a clinical translational tool to evaluate presymptomatic and symptomatic gene positive individuals. Our results provide support that differential tractography has the potential to be used as a dynamic imaging biomarker to assess at the individual level in a non-invasive manner, disease progression in HD. Critically important, differential tractography proves to be a quantitative tool for following degeneration in presymptomatic patients, with potential applications in clinical trials.

Reduction of giant parietooccipital fibrous dysplasia using dynamic mirror image guidance: a case report and review of the literature.

BACKGROUND: Craniofacial fibrous dysplasia (CFD) typically occurs in the facial bones and anterior cranial vault and can produce both disfigurement and functional limitations for patients disfigurement. Treatment consists of reducing the abnormal bone. Bone contouring can become challenging when the exposure does not extend to the corresponding normal contralateral structures for comparison or when normal landmarks are not available, which may compromise the overall aesthetic outcome. We describe a technique using dynamic mirroring to accurately contour the involved part of the cranium in a case of giant CFD. OBSERVATIONS: A 49-year-old male presented with a giant deforming fibrous dysplasia of the right mastoid and parieto-temporo-occiput that was causing functional limitations due to the size of the bony mass. This was managed with multidisciplinary bony reduction. Several neurovascular structures were in proximity to the areas of planned drilling of the expansile lesion, and dynamic mirroring of the uninvolved left skull was utilized to maximize safety and symmetry of reduction. High-speed drilling of the right occipital bone was performed until the navigation system alerted the surgeon that symmetric depth had been achieved. There were no complications from the procedure and this technique maximized the limits of symmetric reduction without significantly increasing surgical complexity or duration. LESSONS: Dynamic mirroring of bony structures in the posterior cranium is not commonly employed in neurosurgical practice. This technique may help improve the aesthetic outcomes of bony reduction in craniofacial dysplasia and a variety of similarly managed bony lesions, contour cranioplasties, and in unilateral craniosynostosis surgery.

Coronavirus Disease 2019 (COVID-19) and Neurosurgery Residency Action Plan: An Institutional Experience from the United States.

BACKGROUND: The current pandemic crisis, caused by a novel human coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), has forced a dramatic change in our society. A key portion of the medical work force on the frontline is composed of resident physicians. Thus, it becomes imperative to create an adequate and effective action plan to restructure this valuable human resource amid the SARS-CoV2 pandemic. We sought to describe a comprehensive approach taken by a Neurosurgery Department in quaternary care academic institution in the United States of America amid the SARS-CoV2 pandemic focused in resident training and support. OBJECTIVE: To describe a comprehensive approach taken by a Neurosurgery Department in quaternary care academic institution in the United States of America amid the SARS-CoV2 pandemic focused on resident training and support. RESULTS: A restructuring of the Neurosurgery Department at our academic institution was performed focused on decreasing their risk of infection/exposure and transmission to others, while minimizing negative consequences in the training experience. An online academic platform was built for resident education, guidance, and support, as well as continue channel for pandemic update by the department leadership. CONCLUSIONS: The SARS-CoV2 pandemic constitutes a global health emergency full of uncertainty. Treatment, scope, duration, and economic burden forced a major restructuring of our medical practice. In this regard, academic institutions must direct efforts to diminish further negative impact in the training and education of the upcoming generation of physicians, including those currently in medical school. Perhaps the only silver lining in this terrible disruption will be greater appreciation of the role of current health care providers and educators, whose contributions to our society are often neglected or unrecognized.

Endoscopic Endonasal Petrosectomy: Anatomical Investigation, Limitations, and Surgical Relevance.

BACKGROUND: The endoscopic endonasal approach (EEA) was recently added to the neurosurgical armamentarium as an alternative approach to the petrous apex (PA) region. However, the maximal extension, anatomical landmarks, and indications of this procedure remain to be established. OBJECTIVE: To investigate the limitations and suggest a classification of PA lesions for endoscopic petrosectomy. METHODS: Five anatomical specimens were dissected with EEA to the PA. Anatomical landmarks for the surgical steps and maximal limits were noted. Pre- and postprocedural computed tomographic scan and image-guidance were used. Relevant surgical cases were reviewed and presented. RESULTS: We defined 3 types of petrosectomy: medial, inferior, and inferomedial. Medial petrosectomy was limited within the paraclival internal carotid artery (ICA) anteriorly, lacerum ICA inferiorly, abducens nerve superiorly, and petrous ICA laterally. Among those, abducens nerve and petrous ICA are surgical limits. Full skeletonization of the paraclival ICA and removal of the lingual process are essential for better access to the medial aspect of PA. Inferior petrosectomy was defined by the lacerum foramen synchondrosis anteriorly, jugular foramen inferiorly, internal acoustic canal posteriorly, and PA superolaterally. Those are surgical limits except for the foramen lacerum synchondrosis. The connective tissue at the pterygosphenoidal fissure was a key landmark for the sublacerum approach. Clinical cases in 3 types of PA lesions were presented. CONCLUSION: The EEA provides access to the medial and inferior aspects of the PA. Several technical maneuvers, including paraclival and lacerum ICA skeletonization, sublacerum approach, and lingual process removal, are key to maximize PA drilling.

Subtemporal transtentorial approach for resection of a pontomesencephalic cavernous malformation.

In this 3D video we review the case of a pontomesencephalic cavernous malformation in a 27-year-old woman who presented with hemiparesis and diplopia. The cavernous malformation was completely resected through a subtemporal transtentorial approach and an epitrigeminal brainstem entry zone, with a significant improvement in the patient's hemiparesis. The relevant anatomy is reviewed in detail through multiple anatomical brainstem dissection specimens, as well as high-definition fiber tractography images. The rationale for the approach is analyzed relative to other possible options, and a number of technical pearls are provided. The video can be found here: https://youtu.be/8EoIWL7XqAc.

Far lateral approach for resection of lower pontine cavernous malformation.

In this 3D video we review the case of a lower pontine cavernous malformation in a 31-year-old man who presented with hemiparesis and an abducens palsy. The cavernous malformation was completely resected through a far lateral approach and a peritrigeminal brainstem entry zone, with a significant improvement in the patient's hemiparesis. The relevant anatomy is reviewed in detail through multiple anatomical brainstem dissection specimens, as well as high-definition fiber tractography images. The rationale for the approach is analyzed relative to other possible options, and a number of technical pearls are provided. The video can be found here: https://youtu.be/fH2Q7RjlBKQ.

Left Sylvian Fissure Epidermoid Cyst Presenting with Progressive Aphasia.

INTRODUCTION: Epidermoid cysts within the sylvian fissure are extremely rare. Expressive aphasia and neurocognitive dysfunction because of mass effect have never been reported previously. CASE PRESENTATION: We discuss the case of a 53-year-old male who presented with an acute episode of expressive aphasia and vision changes along with progressive headaches and cognitive slowing over the 2.5 years prior to presentation. A detailed neurologic examination revealed subtle conductive aphasia, as well as mild short-term memory dysfunction. Magnetic resonance imaging revealed a cystic mass consistent with epidermoid cyst within the left sylvian fissure. High-definition fiber tractography showed that the arcuate fasciculus was stretched by the tumor. A left frontotemporal craniotomy allowed for near-total excision of the cyst and led to rapid and complete resolution of symptoms. CONCLUSION: Although rare, epidermoid cysts of the dominant sylvian fissure can present with progressive aphasia due to mass effect on the arcuate fasciculus. Despite the long-standing symptoms, surgical resection can lead to their complete resolution.

Endoscopic Endonasal Transclival Approach for Resection of a Pontine Glioma: Surgical Planning, Surgical Anatomy, and Technique.

BACKGROUND: The endoscopic endonasal approach (EEA) has been proposed as a potential alternative for ventral brainstem lesions. The surgical anatomy, feasibility, and limitations of the EEA for intrinsic brainstem lesions are still poorly understood. OBJECTIVE: To describe the surgical planning, anatomy, and technique of an intrinsic pontine glioma operated via EEA. METHODS: Six-human brainstems were prepared for white matter microdissection. Ten healthy subjects were studied with high-definition fiber tractography (HDFT). A 56-yr-old female with right-hemiparesis underwent EEA for an exophytic pontine glioma. Pre- and postoperative HDFTs were implemented. RESULTS: The corticospinal tracts (CSTs) are the most eloquent fibers in the ventral brainstem. At the pons, CSTs run between the pontine nuclei and the middle cerebellar peduncle (MCP). At the lower medulla, the pyramidal decussation leaves no room for safe ventral access. In our illustrative case, preoperative HDFT showed left-CST displaced posteromedially and partially disrupted, right-CST posteriorly displaced, and MCP severely disrupted. A transclival exposure was performed achieving a complete resection of the exophytic component with residual intra-axial tumor. Immediately postop, patient developed new left-side abducens nerve palsy and worse right-hemiparesis. Ten days postop, her strength returned to baseline. HDFT showed preservation and trajectory restoration of the CSTs. CONCLUSION: The EEA provides direct access to the ventral brainstem, overcoming the limitations of lateral approaches. For intrinsic pathology, HDFT helps choosing the most appropriate surgical route/boundaries for safer resection. Further experience is needed to determine the indications and limitations of this approach that should be performed by neurosurgeons with high-level expertise in EEA.

Minimally Invasive Approaches for Anterior Skull Base Meningiomas: Supraorbital Eyebrow, Endoscopic Endonasal, or a Combination of Both? Anatomic Study, Limitations, and Surgical Application.

BACKGROUND: Minimally invasive accesses to the anterior skull base include the endoscopic endonasal approach (EEA) and the supraorbital eyebrow approach. These 2 are often seen as competing approaches, not alternative or combinatory approaches. In this study, we evaluated the anatomic limitations of each approach and the combined approach for accessing the anterior skull base. METHODS: Ten neurovascular injected cadaver heads were used for the study. The supraorbital approach to the anterior skull base was performed on 5 heads, and EEA was done on the other 5 heads. Then, the supraorbital approach was added to the 5 heads receiving EEA. Visualization and surgical limitations were recorded by the ability to perform resection of the crista galli, anterior clinoid, cribriform plate, and planum sellae. RESULTS: The maximal lateral extension of EEA for anterior skull base was the midorbit line anteriorly but narrowing down toward the orbital apex. The limitation of the supraorbital approach was found mostly medial and anterior. Drilling of anterior skull base was impossible medially between the sphenoethmoidal suture and the posterior aspect of the crista galli. The combined approach showed complementary areas of visualization and surgical maneuverability. Three clinical cases were presented to illustrate the indications for the stand-alone supraorbital approach, EEA, and combined approach. CONCLUSION: The limitations of the EEA when dealing with lateral extension of anterior skull base meningiomas, and the limitations of the supraorbital eyebrow approach for medial skull base drilling and reconstruction, can be overcome by a judicious, anatomically based combination of both approaches.

Generalized q-sampling imaging fiber tractography reveals displacement and infiltration of fiber tracts in low-grade gliomas.

PURPOSE: Low-grade gliomas (LGGs) are slow growing brain tumors that often cause displacement and/or infiltration of the surrounding white matter pathways. Differentiation between infiltration and displacement of fiber tracts remains a challenge. Currently, there is no reliable noninvasive imaging method capable of revealing such white matter alteration patterns. We employed quantitative anisotropy (QA) derived from generalized q-sampling imaging (GQI) to identify patterns of fiber tract alterations by LGGs. METHODS: Sixteen patients with a neuropathological diagnosis of LGG (WHO grade II) were enrolled. Peritumoral fiber tracts underwent qualitative and quantitative evaluation. Contralateral hemisphere counterparts were used for comparison. Tracts were qualitatively classified as unaffected, displaced, infiltrated or displaced, and infiltrated at once. The average QA of whole tract (W), peritumoral tract segment (S), and their ratio (S/W) were obtained and compared to the healthy side for quantitative evaluation. RESULTS: Qualitative analysis revealed 9 (13.8%) unaffected, 24 (36.9%) displaced, 13 (20%) infiltrated, and 19 (29.2%) tracts with a combination of displacement and infiltration. There were no disrupted tracts. There was a significant increase in S/W ratio among displaced tracts in the pre-operative scans in comparison with the contralateral side. QA values of peritumoral tract segments (S) were significantly lower in infiltrated tracts. CONCLUSION: WHO grade II LGGs might displace, infiltrate, or cause a combination of displacement and infiltration of WM tracts. QA derived from GQI provides valuable information that helps to differentiate infiltration from displacement. Anisotropy changes correlate with qualitative alterations, which may serve as a potential biomarker of fiber tract integrity.

Iatrogenic seeding of skull base chordoma following endoscopic endonasal surgery.

OBJECTIVE: Iatrogenic tumor seeding after open surgery for chordoma has been well described in the literature. The incidence and particularities related to endoscopic endonasal surgery (EES) have not been defined. METHODS: The authors retrospectively reviewed their experience with EES for clival chordoma, focusing on cases with iatrogenic seeding. The clinical, radiographic, pathological, and molecular characterization data were reviewed. RESULTS: Among 173 EESs performed for clival chordomas at the authors' institution between April 2003 and May 2016, 2 cases complicated by iatrogenic seeding (incidence 1.15%) were identified. The first case was a 10-year-old boy, who presented 21 months after an EES for a multiply recurrent clival chordoma with a recurrence along the left inferior turbinate, distinct from a right petrous apex recurrence. Both appeared as a T2-hypertintense, T1-isointense, and heterogeneously enhancing lesion on MRI. Resection of the inferior turbinate recurrence and debulking of the petrous recurrence were both performed via a purely endoscopic endonasal approach. Unfortunately, the child died 2 years later due progression of disease at the primary site, but with no sign of progression at the seeded site. The second patient was a 79-year-old man with an MRI-incompatible pacemaker who presented 19 months after EES for his clival chordoma with a mass involving the floor of the left nasal cavity that was causing an oro-antral fistula. On CT imaging, this appeared as a homogeneously contrast-enhancing mass eroding the hard palate inferiorly, the nasal septum superiorly, and the nasal process of the maxilla, with extension into the subcutaneous tissue. This was also treated endoscopically (combined transnasal-transoral approach) with resection of the mass, and repair of the fistula by using a palatal and left lateral wall rotational flap. Adjuvant hypofractionated stereotactic CyberKnife radiotherapy was administered using 35 Gy in 5 fractions. No recurrence was appreciated endoscopically or on imaging at the patient's last follow-up, 12 months after this last procedure. In both cases, pathological investigation of the original tumors revealed a fairly aggressive biology with 1p36 deletions, and high Ki-67 levels (10%-15%, and > 20%, respectively). The procedures were performed by a team of right-handed surgeons (otolaryngology and neurosurgery), using a 4-handed technique (in which the endoscope and suction are typically passed through the right nostril, and other instruments are passed through the left nostril without visualization). CONCLUSIONS: Although uncommon, iatrogenic seeding occurs during EES for clival chordomas, probably because of decreased visualization during tumor removal combined with mucosal trauma and exposure of subepithelial elements (either inadvertently or because of mucosal flaps). In addition, tumors with more aggressive biology (1p36 deletions, elevated Ki-67, or both) are probably at a higher risk and require increased vigilance on surveillance imaging and endoscopy. Further prospective studies are warranted to evaluate the authors' proposed strategies for decreasing the incidence of iatrogenic seeding after EES for chordomas.

Surgical Management of Vertex Epidural Hematoma: Technical Case Report and Literature Review.

BACKGROUND: Vertex epidural hematoma (VEH) is an uncommon presentation of extra-axial hematomas. It can represent a surgical dilemma regarding when and how to operate, particularly considering the potential implication of the superior sagittal sinus (SSS). OBJECTIVE: Here, we illustrate the surgical technique for VEH as well as a review of the existing literature. METHODS: A 60-year-old man sustained a ground-level fall resulting in complete diastasis of the sagittal suture with underlying large VEH causing significant mass effect on the SSS and bihemispheric convexities. Twenty-four hours later, the patient deteriorated, with decreased level of alertness and worsening asymmetric paresis on his lower extremities. He subsequently underwent surgical evacuation of the hematoma, decompression of the SSS, and fracture repair. A modified bicoronal approach, with bilateral parasagittal craniotomies, was performed. A central island of bone was left intact to spare the diastatic fracture from the craniotomies. This was done to ensure a stable anchor point for tacking-up the underlying displaced dura and SSS. The central bone prevents extensive bleeding from the diastatic fracture and eliminates the risk of further blood reaccumulation and tearing of a possible injured sinus during bone flap elevation. RESULTS: The technique performed allowed us to evacuate completely the hematoma while preserving the SSS and repairing the sagittal suture to avoid further bleeding. Complete neurologic recovery of the patient occurred after VEH evacuation. CONCLUSIONS: Because of its rare nature, VEH represents a surgical challenge. Because neurosurgeons encounter this condition relatively infrequently, literature regarding the medical and surgical management of this entity is warranted.

High-Definition Fiber Tractography in the Evaluation and Surgical Planning of Lhermitte-Duclos Disease: A Case Report.

BACKGROUND: Preoperative delineation of normal tissue displacement patterns in Lhermitte-Duclos disease has not been feasible with conventional imaging means. Surgical resection of this type of lesion remains challenging, because the boundaries of the lesion are indistinguishable during surgery. CASE DESCRIPTION: The clinical presentation, preoperative and postoperative magnetic resonance imaging (MRI) findings, high-definition fiber tractography (HDFT) and histopathological studies, are presented in a 46-year-old male subject with symptomatic Lhermitte-Duclos disease. HDFT was performed using a quantitative anisotropy-based generalized deterministic tracking algorithm to define fiber tracts. Displacement of the cerebellar and brainstem tracts on the affected side was performed using the unaffected contralateral side as a comparison. The displacement of the normal tissues was not apparent on preoperative MRI but was immediately evident on the preoperative HDFT. Of note, there was a relative paucity of fiber tracts within the lesion. By tailoring our operative boundaries based on the HDFT findings, we were able to spare the displaced fiber tracts when debulking the tumor. Restoration of normal fiber tract anatomy on postoperative HDFT imaging was correlated with clinical resolution of preoperative symptoms. CONCLUSIONS: This case report suggests that HDFT may be a powerful surgical planning tool in cases of Lhermitte-Duclos disease, in which the pattern of normal tissue displacement is not evident with conventional imaging, allowing maximal lesion resection without damage to the unaffected tracts. Therefore, this report contributes to solving the greatest challenge when operating on this type of lesion, which has not been resolved in any previous report in our review of the English literature.