A Comparative Study Between Traditional Microscopic Surgeries and Endoscopic Endonasal Surgery for Skull Base Chordomas.

BACKGROUND: Skull base chordomas (SBCs) are rare clinically aggressive neoplasms, developing local recurrences after surgical resection. Although SBCs have traditionally been resected by craniotomy or microscopic transsphenoidal surgery (TSS), the recent development of the endoscopic endonasal approach (EEA) has revolutionized treatment strategies through minimally invasive techniques. This study aimed to evaluate clinical outcomes after traditional microsurgeries or EEAs for SBCs. METHODS: The present retrospective study investigated 66 patients with primary SBCs who underwent surgery between 1977 and 2019. Resection was performed via EEA in 17 cases, craniotomy in 23, transoral approach in 8, TSS in 12, staged surgery in 4, and others in 2. The median follow-up period for progression-free survival (PFS) was 19.5 months. RESULTS: There were no significant differences in preoperative tumor volume or resection rate among these approaches. The incidence of postoperative cranial nerve palsy was significantly lower in EEA than that in craniotomy (P < 0.05). Although total resection was observed in 4 cases of EEA expanding into the superior and inferior part of the clivus, no cases of transoral approach or TSS achieved total resection for both parts. No significant difference in PFS was found among these approaches. Multivariate analysis showed that being female and the absence of radiotherapy were significantly associated with shorter PFS (P < 0.05 and P < 0.001, respectively). The resection rate was not associated with PFS. CONCLUSIONS: EEA is a less invasive surgical approach for SBCs. The development of surgical instruments and postoperative radiotherapy will further improve patients' outcomes.

Crowned Dens Syndrome Occurred in a Patient after Simple Drainage for Chronic Subdural Hematoma: A Case Report.

Crowned dens syndrome (CDS) is a rare disease which presents with neck pain and rigidity. A 74-year-old man with right chronic subdural hematoma (CSDH) underwent hematoma drainage. After the operation, he complained of neck pain and laboratory test revealed elevation of C-reactive protein (CRP) and white blood cell (WBC). Suspecting localized infection, wound irrigation was performed. Neck pain relieved after irrigation, but we could not find the source of infection. CDS was diagnosed by computed tomography (CT). CDS is frequently misdiagnosed as meningitis and localized infection. CT is useful for diagnosis. Neurosurgeons need to be aware of CDS after operation.

Leukoencephalopathy, cerebral calcifications, and cysts: A clinical case involving a long-term follow-up and literature review.

BACKGROUND: Leukoencephalopathy, cerebral calcifications, and cysts (LCC) is a rare disease that was first reported by Labrune in 1996. A case of adult-onset LCC was successfully followed up for a long period. CASE PRESENTATION: A 30-year-old female presented with visual field disturbance and seizure on several occasions. Radiographic images revealed multiple supratentorial cysts and calcifications in the bilateral nucleus basalis and cerebella. Aspiration, Ommaya reservoir placement, and nodule removal were performed for the responsible cysts, and the patient had a good postoperative course. DISCUSSION: A tiny, strongly enhanced nodule was identified before cyst formation on her radiographic images. Thus, cyst growth may be related to nodule microbleeding. According to our review, if the responsible cyst is located on the noneloquent area, surgical removal of the cyst should be considered. However, if the responsible cyst is located on the eloquent area, the nodule should be first removed because nodules can bleed and enlarge cysts. CONCLUSION: Careful follow-up is needed, especially for cysts with a strongly enhanced nodule.

Improvement of long-term blindness caused by compression from inner-third sphenoid wing meningioma after optic canal decompression: An extremely rare case report.

BACKGROUND: There has been no previous case report of a patient whose visual acuity improved after long-term blindness caused by tumor invasion into the optic canal. CASE DESCRIPTION: A 65-year-old Asian woman presented with a 6-month history of blindness caused by a meningioma located on the inner third of the sphenoid ridge. An operation was performed to prevent further tumor invasion into the cavernous sinus and contralateral optic nerve. During surgery, optic canal decompression was performed using an epidural approach. Subtotal removal of the tumor was achieved. Two days after the surgery, her left visual acuity recovered from blindness. CONCLUSION: Normally, long-term blindness caused by optic nerve compression by a brain tumor is regarded as irreversible, and even a surgical excision of the optic nerve is performed in some cases. However, because we experienced a case in which the patient recovered from long-term blindness after optic canal decompression, we believe that this surgical procedure should definitely be considered as an option.

Visualization of the electric field evoked by transcranial electric stimulation during a craniotomy using the finite element method.

BACKGROUND: Transcranial MEP (tMEP) monitoring is more readily performed than cortical MEP (cMEP), however, tMEP is considered as less accurate than cMEP. The craniotomy procedure and changes in CSF levels must affect current spread. These changes can impair the accuracy. The aim of this study was to investigate the influence of skull deformation and cerebrospinal fluid (CSF) decrease on tMEP monitoring during frontotemporal craniotomy. METHODS: We used the finite element method to visualize the electric field in the brain, which was generated by transcranial electric stimulation, using realistic 3-dimensional head models developed from T1-weighted images. Surfaces of 5 layers of the head were separated as accurately as possible. We created 3 brain types and 5 craniotomy models. RESULTS: The electric field in the brain radiates out from the cortex just below the electrodes. When the CSF layer is thick, a decrease in CSF volume and depression of CSF surface level during the craniotomy has a major impact on the electric field. When the CSF layer is thin and the distance between the skull and brain is short, the craniotomy has a larger effect on the electric field than the CSF decrease. COMPARISON WITH EXISTING METHOD: So far no report in the literature the electric field during intraoperative tMEP using a 3-dimensional realistic head model. CONCLUSION: Our main finding was that the intensity of the electric field in the brain is most affected by changes in the thickness and volume of the CSF layer.

Usefulness of facial nerve monitoring for confirmation of greater superficial petrosal nerve in anterior transpetrosal approach.

INTRODUCTION: The greater superficial petrosal nerve (GSPN) is especially important in anterior transpetrosal approach (ATPA) as the most reliable superficial landmark of Kawase's triangle. The GSPN can be considered as the superficial lateral border of anterior petrosectomy on the middle fossa to avoid internal carotid artery (ICA) injury. Although experienced operators can find the GSPN, its confirmation is not always easy to achieve. METHODS: We introduce our recent GSPN confirmation methods using facial nerve monitoring. In 10 recent cases, antidromic GSPN stimulation and free-running facial muscle electromyography (EMG) monitoring were performed. RESULTS: Facial nerve evoked-EMG by antidromic GSPN stimulation confirmed the location of the GSPN course with precision in all cases. Free-running facial muscle EMG informed the mechanical stress of facial nerves through the GSPN. There was no postoperative facial palsy or dry eye in these cases. CONCLUSIONS: GSPN confirmation and preservation are not always easy to achieve. These monitoring methods are useful for the confirmation of the GSPN, which is a landmark for safe extradural anterior petrosectomy, and for the preservation of the GSPN itself.