Open Surgical Approaches for Meningiomas

Meningiomas are the most common intracranial extra-axial primary tumor. Although most are low grade and slow growing, resection can be technically challenging, particularly when located at the skull base. Appropriate craniotomy and approach selection are of paramount importance to minimize brain retraction, optimize exposure, and achieve complete resection. This article summarizes various craniotomies and their approaches to meningiomas, and illustrates some nuances in performing these techniques with cadaveric dissection and operative videos.

Polymorphous low-grade neuroepithelial tumor of the young: Rare tumor and review of the literature

Polymorphous low-grade neuroepithelial tumor of the young (PLNTY) is a recently described low-grade neuroepithelial tumor with an infiltrative growth pattern and oligodendrocyte-like cells that are CD34 immunopositive. Correlating histology and results from molecular testing is critical to correctly diagnosing PLNTY, as its histologic appearance is similar to oligodendrogliomas and shares genetic abnormalities common to other low-grade epilepsy associated tumors (LEATs). In this case report, we describe a 31-year-old female with intractable epilepsy found to have a temporal mass and diagnosed with PLNTY after histopathologic and molecular testing. We describe the radiographic, histologic, and genetic features in relation to the epileptic and oncologic outcomes for this patient. Then, we compare these features and outcomes to other cases of PLNTY described in the literature.

Vidian Canal as a Transcranial Landmark: Anatomy, Technique, and Illustrative Cases

Objective The vidian nerve can be accessed in transcranial approaches in carefully selected patients to ensure its preservation and to serve as a landmark for sphenoid sinus entry. This report is to review a technique, evaluate it in laboratory settings, and present two illustrative cases.

Design The study involves cadaveric dissection and illustrative cases.

Setting The study conducted in a cadaveric dissection laboratory.

Participants The object of the study is one cadaveric head and two illustrative clinical cases.

Main Outcome Measures Two cases using this approach were illustrated, and a cadaver dissection was performed in a step-by-step fashion.

Results: The vidian canal can be accessed by drilling the anterolateral triangle. Two illustrated cases were presented; in one, the vidian nerve was used as part of a corridor to access the sphenoid sinus for tumor delivery, and in the other, the technique was used to find and preserve the vidian nerve during transcranial resection.

Conclusion Careful identification of the vidian canal in transcranial surgery is a beneficial technique in carefully selected cases which allows identification of the nerve both for its preservation in selected cases and to create the vidian–maxillary corridor for tumor resection. Knowing the anatomy and pneumatization variants is important in the surgical approach.

Anatomy and White Matter Connections of the Superior Parietal Lobule

BACKGROUND

The superior parietal lobule (SPL) is involved in somatosensory and visuospatial integration with additional roles in attention, written language, and working memory. A detailed understanding of the exact location and nature of associated white matter tracts could improve surgical decisions and subsequent postoperative morbidity related to surgery in and around this gyrus.

OBJECTIVE

To characterize the fiber tracts of the SPL based on relationships to other well-known neuroanatomic structures through diffusion spectrum imaging (DSI)-based fiber tracking validated by gross anatomical dissection as ground truth.

METHODS

Neuroimaging data of 10 healthy, adult control subjects was obtained from a publicly accessible database published in Human Connectome Project for subsequent tractographic analyses. White matter tracts were mapped between both cerebral hemispheres, and a lateralization index was calculated based on resultant tract volumes. Post-mortem dissections of 10 cadavers identified the location of major tracts and validated our tractography results based on qualitative visual agreement.

RESULTS

We identified 9 major connections of the SPL: U-fiber, superior longitudinal fasciculus, inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, middle longitudinal fasciculus, extreme capsule, vertical occipital fasciculus, cingulum, and corpus callosum. There was no significant fiber lateralization detected.

CONCLUSION

The SPL is an important region implicated in a variety of tasks involving visuomotor and visuospatial integration. Improved understanding of the fiber bundle anatomy elucidated in this study can provide invaluable information for surgical treatment decisions related to this region.

Anatomy and White Matter Connections of the Lingual Gyrus and Cuneus

BACKGROUND

The medial occipital lobe, composed of the lingual gyrus and cuneus, is necessary for both basic and higher level visual processing. It is also known to facilitate cross-modal, nonvisual functions, such as linguistic processing and verbal memory, after the loss of the visual senses. A detailed cortical model elucidating the white matter connectivity associated with this area could improve our understanding of the interacting brain networks that underlie complex human processes and postoperative outcomes related to vision and language.

METHODS

Generalized q-sampling imaging tractography, validated by gross anatomic dissection for qualitative visual agreement, was performed on 10 healthy adult controls obtained from the Human Connectome Project.

RESULTS

Major white matter connections were identified by tractography and validated by gross dissection, which connected the medial occipital lobe with itself and the adjacent cortices, especially the temporal lobe. The short- and long-range connections identified consisted mainly of U-shaped association fibers, intracuneal fibers, and inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, middle longitudinal fasciculus, and lingual-fusiform connections.

CONCLUSIONS

The medial occipital lobe is an extremely interconnected system, supporting its ability to perform coordinated basic visual processing, but also serves as a center for many long-range association fibers, supporting its importance in nonvisual functions, such as language and memory. The presented data represent clinically actionable anatomic information that can be used in multimodal navigation of white matter lesions in the medial occipital lobe to prevent neurologic deficits and improve patients' quality of life after cerebral surgery.

Anatomy and White Matter Connections of the Middle Frontal Gyrus

BACKGROUND

The middle frontal gyrus (MFG) is involved in attention, working memory, and language-related processing. A detailed understanding of the subcortical white matter tracts connected within the MFG can facilitate improved navigation of white matter lesions in and around this gyrus and explain the postoperative morbidity after surgery. We aimed to characterize the fiber tracts within the MFG according to their connection to neuroanatomic structures through the use of diffusion spectrum imaging-based fiber tractography and validate the findings by gross anatomic dissection for qualitative visual agreement.

METHODS

Tractography analysis was completed using diffusion imaging data from 10 healthy, adult subjects enrolled in the Human Connectome Project. We assessed the MFG as a whole component according to its fiber connectivity with other neural regions. Mapping was completed on all tracts within both hemispheres, with the resultant tract volumes used to calculate a lateralization index. A modified Klingler technique was used on 10 postmortem dissections to demonstrate the location and orientation of the major tracts.

RESULTS

Two major connections of the MFG were identified: the superior longitudinal fasciculus, which connects the MFG to parts of the inferior parietal lobule, posterior temporal lobe, and lateral occipital cortex; and the inferior fronto-occipital fasciculus, which connected the MFG to the lingual gyrus and cuneus. Intra- and intergyral short association, U-shaped fibers were also identified.

CONCLUSIONS

Subcortical white matter pathways integrated within the MFG include the superior longitudinal fasciculus and inferior fronto-occipital fasciculus. The MFG is implicated in a variety of tasks involving attention and memory, making it an important cortical region. The postoperative neurologic outcomes related to surgery in and around the MFG could be clarified in the context of the anatomy of the fiber bundles highlighted in the present study.

Laser Interstitial Thermal Therapy Case Series: Choosing the Correct Number of Fibers Depending on Lesion Size

BACKGROUND

Laser interstitial thermal therapy (LITT) is being used for the treatment of recurrent glioblastoma multiforme (GBM). Lesions can be treated using 1 or multiple LITT fibers depending on the preference of surgeons. Usually, more fibers are needed for coverage of larger tumors.

OBJECTIVE

To investigate and analyze how tumor size affected the number of LITT fibers used.

METHODS

This is a retrospective review of patients undergoing treatment of recurrent GBM. Patients were treated with up to 4 LITT fibers for adequate tumor coverage. Patient demographics, tumor characteristics, length of stay, complications, and biopsy results were recorded.

RESULTS

A total of 43 cases were treated using LITT, and of these cases, 31 consisted of contiguous lesions. We used more fibers to treat larger tumor volumes. On average, for each 5 cc of tumor volume, a fiber was added for proper coverage (P = .554). Complications and length of stay were similar across the groups (P = .378, P = .941).

CONCLUSION

LITT can be used for the treatment of recurrent GBM. For each 5 cc of tumor volume, a LITT fiber can be added to the treatment plan.

Laser Interstitial Thermal Therapy for Metastatic Melanoma After Failed Radiation Therapy: A Case Series

BACKGROUND

Laser interstitial thermal therapy (LITT) is a growing technology to treat a variety of brain lesions. It offers an alternative to treatment options, such as open craniotomy and stereotactic radiosurgery.

OBJECTIVE

To analyze our experience using LITT for metastatic melanoma.

METHODS

This is a retrospective chart review of the patients from our institution. Our case series involves 5 patients who had previously failed radiation treatment.

RESULTS

Our patients have low complication rates and short hospital stays. Both are considerably lower when compared to the literature for metastatic melanoma.

CONCLUSION

LITT is a safe therapy, with few complications and short hospital stays.

Diffusion Tensor Imaging Tractography for Fornix Identification in Intraventricular Tumor Surgery: A Case Series

BACKGROUND

The proximity of intraventricular or periventricular tumors to critical white matter structures, such as the fornix, poses an operative challenge. In order to avoid significant neurological morbidity, deliberate selection of surgical approach is necessary when planning resection of tumors in this region. We report our initial experience with fornix modeling as an adjunct to standard navigational techniques across multiple pathologies.

OBJECTIVE

To report the feasibility of using diffusion tensor imaging (DTI) fornix modeling as an adjunct to standard navigational techniques for surgical treatment of intraventricular and periventricular tumors involving the fornix.

METHODS

Between July 2018 and August 2019, DTI tractography was performed on 12 patients with intraventricular or periventricular tumors involving the fornix. DTI fornix modeling was performed and included as part of the intraoperative navigation in all cases.

RESULTS

The patient group was composed of 6 males and 6 females. The fornix model was delineated in all cases using DTI tractography as described. The mean patient age was 45.7 yr. The 2 most-common tumor pathologies represented in our patient cohort included meningioma and cranipharyngioma, both found in 2 patients. A glioneuronal tumor, low-grade glioma, ependymoma, subependymoma, mixed germ-cell tumor, pituitary adenoma, and renal cell carcinoma metastasis were found in 1 patient each. Case examples of fornix modeling that may be incorporated into standard neuronavigation are presented. No patient experienced new or worsening post-operative memory deficits.

CONCLUSION

DTI tractography for fornix identification is a useful adjunct to standard navigational techniques employed in surgical resection of forniceal involving tumors.

Surgical Treatment of Tethered Cord Syndrome in Adults: A Systematic Review and Meta-Analysis

OBJECTIVE

In the healthy spine, the spinal cord moves unimpeded with spinal fluid pulsation in the rostral and caudal directions. When a portion of the spinal cord becomes attached to lesions within the spinal column, excess strain can cause signs and symptoms such as pain, motor deficits, sensory deficits, bladder dysfunction, and bowel dysfunction. This condition is termed tethered cord syndrome. There are no clear guidelines for offering surgical intervention, although there is a general consensus that worsening signs and symptoms increase the likelihood that patients will need surgery.

METHODS

In this article, we conduct a systematic review and meta-analysis for all available literature within the Ovid (MEDLINE), PubMed, and Google Scholar databases to evaluate common symptoms among patients with tethered cord and to examine how surgery affects symptoms.

RESULTS

Within the cohort of 730 patients, 708 (97%) were treated surgically by a detethering procedure. The most common preoperative sign or symptom was pain (81%), followed by motor deficits (63%), sensory deficits (61%), bladder dysfunction (56%), and bowel dysfunction (15%). One percent of patients had no deficit or symptom. Pain was the symptom that was most responsive to surgery, with 81% of patients reporting that their pain improved after detethering.

CONCLUSIONS

Tethered cord syndrome should be included in the differential diagnosis in patients presenting with back or leg pain, somatosensory symptoms of the lower extremities, muscular weakness, urodynamic dysfunction, or bowel dysfunction. After a definitive diagnosis is made, patients should be counseled about surgical detethering as an option.

Anterior cervical discectomy and fusion requiring resection of the superior horn of thyroid cartilage: case report

Anterior cervical discectomy and fusion (ACDF) is the most common surgical procedure utilized for degenerative diseases of the cervical spine. The authors present the case of a 64-year-old man who underwent an ACDF for degenerative changes causing cervical stenosis with myelopathy. The patient's symptoms consisted of pain and weakness of the bilateral upper extremities that slowly progressed over 1.5 years. During the procedure, the superior horn of the thyroid cartilage impeded proper retraction, preventing adequate visualization due to its prominent size. At this point, otorhinolaryngology was consulted, which allowed for safe resection of this portion of the thyroid cartilage while preserving nearby critical structures. With the frequent usage of this surgical approach for various etiologies, the importance of proper recognition and consultation is paramount. Encountering prominent thyroid cartilage resulting in surgical obstruction has not been described in the literature and this report represents a paradigm for the proper course of action.

Neurochemical supplementation in patients with depressed levels of participation after brain tumor surgery: Rationale and preliminary results

A unique challenge in some brain tumor patients is the fact that tumors arising in certain areas of the brain involve the neural structures of consciousness or alertness, limiting the patient's ability to participate in rehabilitation following surgery. A critical question is whether neurostimulant therapy can help patients participate in rehabilitation efforts. We performed a retrospective review of all patients undergoing brain tumor surgery by the senior author from 2012 to 2018. We limited this study to patients with tumors occupying critical structures related to consciousness, alertness, and motor initiation. A combination of methylphenidate and levodopa/carbidopa was used to monitor the progress of patients through neurorehabilitation efforts. We identified 101 patients who experienced an inability to participate in rehabilitation (ITPR) in the post-operative period. Of these, 86 patients (85%) were treated with methylphenidate and levodopa/carbidopa. Cases of ITPR were related to dysfunction of the brainstem (12/86 cases, 14%), thalamus (17/86 cases, 20%), hypothalamus (14/86 cases, 16%), basal ganglia (13/86 cases, 15%), and medial frontal lobe (30/86 cases, 35%). Of the 86 individuals treated, 47/86 patients (55%) showed early improvement in their ability to participate with rehabilitation. At three month follow-up, 58/86 patients (67%) had returned to living independently or were at least interactive and cooperative during follow-up examination. This feasibility report suggests that combined therapy with methylphenidate and levodopa/carbidopa may help patients participate in neurorehabilitation efforts in the immediate post-operative period following brain tumor surgery. Randomized, controlled clinical trials are needed to explore this concept more thoroughly.

Factors Associated with Treatment Failure and Radiosurgery-Related Edema in WHO Grade 1 and 2 Meningioma Patients Receiving Gamma Knife Radiosurgery

BACKGROUND

Before the advent of radiosurgery, neurosurgical treatment of meningiomas typically involved gross total resection of the mass whenever surgery was deemed possible. Over the past 4 decades, though, Gamma Knife radiosurgery (GKRS) has proved to be an effective, minimally invasive means to control the growth of these tumors. However, the variables associated with treatment failure (regrowth or clinical progression) after GKRS and GKRS-related complications, such as cerebral edema, are less well understood.

METHODS

We retrospectively collected data between 2009 and 2018 for patients who underwent GKRS for meningiomas. After data collection, we performed univariate and multivariable modeling of the factors that predict treatment failure and cerebral edema after GKRS. Hazard ratios (HR) and P values were determined for these variables.

RESULTS

Fifty-two patients were included our analysis. The majority of patients were female (38/52,73%), and nearly all patients presented with a suspected or confirmed World Health Organization grade 1 meningioma (48/52, 92%). The median tumor volume was 3.49 cc (range, 0.22-20.11 cc). Evidence of meningioma progression after treatment developed in 5 patients (10%), with a median time to continued tumor growth of 5.9 months (range, 2.7-18.3 months). In multivariable analysis, patients in whom treatment failed were more likely to be male (HR = 8.42, P = 0.045) and to present with larger tumor volumes (HR = 1.27, P = 0.011). In addition, 5 patients (10%) experienced treatment-related cerebral edema. On univariate analysis, patients who experienced cerebral edema were more likely present with larger tumors (HR = 1.16, P = 0.028).

CONCLUSIONS

Increasing meningioma size and male gender predispose to meningioma progression after treatment with GKRS. Increasing tumor size also predicts the development of postradiosurgery cerebral edema.

Use of Pterional Craniotomy for Removal of Penetrating Object: Case Report and Surgical Video

BACKGROUND

Penetrating injuries are dangerous because they can damage intracranial structures. Removal of the object carries this same risk of injury, so neurosurgeons often visualize the injury via craniotomy during removal.

CASE DESCRIPTION

This report illustrates the case of a 41-year-old man who had a penetrating injury with a knife that started in the left nasal passage and extended to the parasellar region. Computed tomography angiography revealed an associated sphenoid fracture and showed the tip of the knife within the parasellar space with preservation of the internal carotid artery, ophthalmic artery, optic nerve, and pituitary gland. The patient was taken to the operating room for a right pterional craniotomy and the knife was removed in the operating room in a combined effort between neurosurgery and otorhinolaryngology.

CONCLUSIONS

The patient progressed well without complications postoperatively and was discharged 5 days later. We provide a report with video showing our surgical approach for removal of a penetrating object through the tuberculum sellae.

The Artery of Aphasia, A Uniquely Sensitive Posterior Temporal Middle Cerebral Artery Branch that Supplies Language Areas in the Brain: Anatomy and Report of Four Cases

BACKGROUND

Arterial disruption during brain surgery can cause devastating injuries to wide expanses of white and gray matter beyond the tumor resection cavity. Such damage may occur as a result of disrupting blood flow through en passage arteries. Identification of these arteries is critical to prevent unforeseen neurologic sequelae during brain tumor resection. In this study, we discuss one such artery, termed the artery of aphasia (AoA), which when disrupted can lead to receptive and expressive language deficits.

METHODS

We performed a retrospective review of all patients undergoing an awake craniotomy for resection of a glioma by the senior author from 2012 to 2018. Patients were included if they experienced language deficits secondary to postoperative infarction in the left posterior temporal lobe in the distribution of the AoA. The gross anatomy of the AoA was then compared with activation likelihood estimations of the auditory and semantic language networks using coordinate-based meta-analytic techniques.

RESULTS

We identified 4 patients with left-sided posterior temporal artery infarctions in the distribution of the AoA on diffusion-weighted magnetic resonance imaging. All 4 patients developed substantial expressive and receptive language deficits after surgery. Functional language improvement occurred in only 2/4 patients. Activation likelihood estimations localized parts of the auditory and semantic language networks in the distribution of the AoA.

CONCLUSIONS

The AoA is prone to blood flow disruption despite benign manipulation. Patients seem to have limited capacity for speech recovery after intraoperative ischemia in the distribution of this artery, which supplies parts of the auditory and semantic language networks.

The safety of post-operative elevation of mean arterial blood pressure following brain tumor resection

We demonstrate the safety of artificially elevating the mean arterial blood pressure (MAP) greater than 85 mmHg or 10% above the mean MAP in patients with underlying hypertension during the acute post-operative period in patients undergoing surgery for resection of brain tumors. A retrospective review was undertaken of all patients undergoing surgery by the senior author between 2013 and 2018. Patients who underwent MAP therapy were analyzed for hemorrhagic and cardiac complications. A total of 1162 of 2270 post-operative brain tumor patients underwent MAP therapy after surgery for a minimum of 24 h post-operatively. Of these, 7/1162 (0.6%) patients experienced intra-cavitary hemorrhage within 5 days of surgery. Two of 7 (29%) patients were diagnosed with venous infarction. One of 7 (14%) patients experienced post-operative, intra-cavitary hemorrhage prior to the initiation of MAP therapy. The remaining 4/1162 (0.35%) patients experienced intra-cavitary hemorrhage post-operatively without clear etiology. In assessing cardiac outcomes, 2/1162 patients (0.2%) experienced elevated troponin levels. No patient demonstrated significant cardiac related morbidity or mortality within this cohort. Post-operative MAP therapy with a goal of maintaining MAP greater than 85 mmHg or 10% above the mean MAP in patients with underlying hypertension appears to be a safe intervention in brain tumor patients for at least 24 h in the post-operative period.

Co-occurrence of astrocytoma and astroblastoma: Case report and literature review

A 41-year-old man presented to us with left arm and leg weakness and mild word finding difficulties. His preoperative magnetic resonance imaging (MRI) demonstrated abnormal T1 and T2 signal changes in the right temporal lobe and basal ganglia, indicative of possible glioma. An awake craniotomy for right temporal lobectomy was performed and the tumor was resected. Full pathologic workup later revealed the patient had two distinct tumors occurring simultaneously, anaplastic astrocytoma and astroblastoma. We review the literature regarding the treatment of anaplastic astrocytoma and astroblastoma and discuss their co-occurrence.

Hemisacrectomy with preservation of the contralateral sacral nerve roots and sacroiliac joint for pelvic neurofibrosarcoma in a 7-year-old child: case report with 2-year follow-up

Neurofibrosarcoma is rare in the pediatric age group. A malignant tumor of the sacrum presents significant challenges, especially if the goals are to resect with wide and clean surgical margins and to achieve acceptable functional outcomes. The authors report a case of this rare tumor affecting the sacrum and sacral nerve roots of a 7-year-old girl and review the role of total hemisacrectomy sparing the contralateral sacral nerve roots and lumbopelvic reconstruction in the treatment of this disease. This patient is, to the best of the authors' knowledge, the youngest to be treated in this manner.

Biocompatibility of reduced graphene oxide nanoscaffolds following acute spinal cord injury in rats

Background:

Graphene has unique electrical, physical, and chemical properties that may have great potential as a bioscaffold for neuronal regeneration after spinal cord injury. These nanoscaffolds have previously been shown to be biocompatible in vitro; in the present study, we wished to evaluate its biocompatibility in an in vivo spinal cord injury model.

Methods:

Graphene nanoscaffolds were prepared by the mild chemical reduction of graphene oxide. Twenty Wistar rats (19 male and 1 female) underwent hemispinal cord transection at approximately the T2 level. To bridge the lesion, graphene nanoscaffolds with a hydrogel were implanted immediately after spinal cord transection. Control animals were treated with hydrogel matrix alone. Histologic evaluation was performed 3 months after the spinal cord transection to assess in vivo biocompatibility of graphene and to measure the ingrowth of tissue elements adjacent to the graphene nanoscaffold.

Results:

The graphene nanoscaffolds adhered well to the spinal cord tissue. There was no area of pseudocyst around the scaffolds suggestive of cytotoxicity. Instead, histological evaluation showed an ingrowth of connective tissue elements, blood vessels, neurofilaments, and Schwann cells around the graphene nanoscaffolds.

Conclusions:

Graphene is a nanomaterial that is biocompatible with neurons and may have significant biomedical application. It may provide a scaffold for the ingrowth of regenerating axons after spinal cord injury.