Publications by authors named "Jonathan Rychen"

Objective: Despite its potential advantages, robotic surgery has yet to be applied to skull base procedures. Complex anatomy and restricted access have limited the development of robotic skull base surgery. The authors' aim was to conduct a feasibility study of robotic surgery for posterior fossa skull base lesions.

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Objective: The inferior hypophyseal arteries (IHAs) are intimately related to pituitary and cavernous sinus (CS) lesions. There is still no anatomical study specifically analyzing the IHAs. The aim of this study was to investigate the surgical anatomy and variations of the IHA, and to translate this knowledge into surgical practice.

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Background/objectives: Detailed morphometric analysis of an aneurysm and the related vascular bifurcation are critical factors when determining rupture risk and planning treatment for unruptured intracranial aneurysms (UIAs). The standard visualization of digital subtraction angiography (DSA) and its 3D reconstruction on a 2D monitor provide precise measurements but are subject to variability based on the rater. Visualization using virtual (VR) and augmented reality platforms can overcome those limitations.

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Objective: Mastery of the posterior clinoidectomy technique is of utmost importance for neurosurgeons who specialize in endoscopic endonasal approaches, because the posterior clinoid process (PCP) is commonly involved in chondroid tumor resection. Three main techniques for posterior clinoidectomy have been developed: intradural, extradural, and transcavernous interdural. The authors introduce here a novel technical variant in which the transcavernous approach is extended to the dorsal clinoidal space after transection of the caroticoclinoid ligament, and they elaborate on its clinical application on the basis of anatomical dissections and radiological studies.

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Objective: Recurrent cerebrospinal fluid (CSF) rhinorrhea caused by sequential, anatomically separated skull base defects is rarely reported in the literature. Neither management nor etiology has been sufficiently investigated. We present an illustrative case and a systematic review of the literature regarding etiology, diagnostics, and management of this rare phenomenon.

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Thyroid-stimulating hormone-secreting adenomas (TSH-oma) are exceptionally rare.1 The primary treatment is surgical resection with radiation and pharmacotherapy postoperatively if subtotal resection, especially with cavernous sinus invasion.2 We present the case of a 29-year-old man with TSH-oma with cavernous sinus medial wall invasion.

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Objective: The mainstay of treatment for skull base chordoma (SBC) is maximal safe resection followed by radiotherapy. However, even after gross-total resection (GTR), the recurrence rate is high due to microscopic disease in the resection margins. Therefore, supramarginal resection (SMR) could be beneficial, as has been shown for sacral chordoma.

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Objective: Tumors located in the retrochiasmatic region with extension to the third ventricle might be difficult to access when the pituitary-chiasmatic corridor is narrow. Similarly, tumor extension into the interpeduncular and retrosellar space poses a major surgical challenge. Pituitary transposition techniques have been developed to gain additional access.

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Background: H3 K27-altered diffuse midline gliomas (DMGs) are rare tumors, which are, regardless of their histological appearance, classified as World Health Organization grade 4 tumors. They are characterized by a diffuse growth pattern, midline anatomical location, and poor prognosis. Although DMGs occur predominantly in childhood, these tumors can also be found in young adults.

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Objective: The modern management of patients with Koos grade IV vestibular schwannomas (VSs) aims at functional preservation and long-term tumor control. Gross-total resection (GTR) leads to optimal tumor control but frequently also results in permanent facial nerve (FN) palsy. Subtotal resection (STR) or near-total resection (NTR) followed by a wait-and-scan protocol and second-line radiation therapy (RT) in case of progressive residuals yields excellent tumor control rates with less permanent morbidity.

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Objective: Discontinuation of antithrombotics (AT) prior to elective cranial procedures is common practice, despite the higher risk of thromboembolic complications in these patients. The aim of this study was to investigate the risks and benefits of a new perioperative management protocol of continuation or ultra-early AT resumption in elective cranial procedures.

Methods: This study was an analysis of a prospectively collected cohort of patients undergoing elective cranial surgery with (AT group) and without (control group) AT.

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Background: Cerebellar contusion, swelling and herniation is frequently encoutered upon durotomy in patients undergoing retrosigmoid craniotomy for cerebellopontine angle (CPA) tumors, despite using standard methods to obtain adequate cerebellar relaxation.

Objective: The aim of this study is to report an alternative cerebrospinal fluid (CSF)-diversion method using image-guided ipsilateral trigonal ventriculostomy.

Methods: Single-center retro- and prospective cohort study of  = 62 patients undergoing above-mentioned technique.

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Background:  The literature concerning the management of antiplatelet (AP) and anticoagulation (AC) medication in the perioperative phase of craniotomy remains scarce. The aim of this international survey was to investigate the current practice among neurosurgeons regarding their perioperative management of AP and AC medication.

Methods:  We distributed an online survey to neurosurgeons worldwide with questions concerning their perioperative practice with AP and AC medication in patients undergoing craniotomy.

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Background: The etiologies of parkinsonism are diverse. A possible and rare cause of hemiparkinsonism is mechanical compression of the basal ganglia and its connecting white matter tracts. The authors present a case of hemiparkinsonism caused by a lateral sphenoid wing meningioma, discuss the underlying pathophysiology based on tractography, and systematically review the existing literature.

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Background: The minipterional (MPT) craniotomy is a workhorse approach for clipping of middle cerebral artery (MCA) aneurysms. Because it aims to reach the skull base, traction on the temporal muscle is required. As a result, patients may suffer from transient postoperative temporal muscle discomfort.

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Article Synopsis
  • * It finds that vsACoA shows a higher in-hospital bleeding rate compared to aneurysms in other locations, particularly during endovascular treatment, but does not lead to increased morbidity or mortality at discharge.
  • * Overall, while vsACoA has a greater rebleeding risk, the size of the aneurysm (5 to 25 mm) poses a more significant risk factor for neurological deficits than the location of the aneurysm itself.
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Background/aim: Discontinuation of aspirin (ASA) prior to elective craniotomies is common practice. However, patients treated with ASA for secondary prevention bear a higher risk for thromboembolic complications. Aim of this systematic review is to investigate the risks and benefits of perioperative continuation and discontinuation of ASA in elective craniotomies.

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Growing evidence links COVID-19 with acute and long-term neurological dysfunction. However, the pathophysiological mechanisms resulting in central nervous system involvement remain unclear, posing both diagnostic and therapeutic challenges. Here we show outcomes of a cross-sectional clinical study (NCT04472013) including clinical and imaging data and corresponding multidimensional characterization of immune mediators in the cerebrospinal fluid (CSF) and plasma of patients belonging to different Neuro-COVID severity classes.

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Objective: Postoperative internal carotid artery (ICA) intimal flap (IF) is a potential complication after carotid endarterectomy (CEA) for carotid artery stenosis. There are no clear recommendations in the current literature on the management of this condition due to sparse evidence. Some authors advocate carotid stent placement or reoperation, while others suggest watchful waiting.

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Article Synopsis
  • * A study analyzed 274 aSAH patients and found that those receiving early CSF diversion (within 14 days) showcased better consciousness levels and fewer catheter infections compared to those who underwent the procedure later.
  • * However, there were no significant differences in complications related to cerebrospinal fluid diversion obstructiveness or outcomes related to symptomatic delayed cerebral vasospasm and ischemia between the early and late groups, suggesting further research in larger studies is needed to
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Background: Current prognostic tools in aneurysmal subarachnoid hemorrhage (aSAH) are constrained by being primarily based on patient and disease characteristics on admission.

Objective: To develop and validate a complication- and treatment-aware outcome prediction tool in aSAH.

Methods: This cohort study included data from an ongoing prospective nationwide multicenter registry on all aSAH patients in Switzerland (Swiss SOS [Swiss Study on aSAH]; 2009-2015).

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Introduction: Management of spontaneous intracerebral hemorrhage (ICH) remains controversial despite efforts to produce high level evidence in the past few years. We systematically examined the pooled literature data on the natural history and surgical management of ICH.

Evidence Acquisition: A systematic review was performed using the PubMed and Embase databases, encompassing English, full-text articles, reporting treatment outcomes for the conservative and surgical management of ICH.

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: There is a relative lack of literature on long-term aneurysm recurrence and de novo aneurysm formation following surgical treatment of unruptured intracranial aneurysms. This retrospective single-center cohort study, therefore, analyzes the incidence of aneurysm recurrence, and the incidence of de novo aneurysms formation in patients with at least 10yrs of radiological follow-up. The data are put into the context of a systematic review of the literature.

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Background: The supraorbital craniotomy (SOC) is classically performed through a skin incision in the patient's eyebrow. A variant with a skin incision in the patient's eyelid has become increasingly popular in recent years.

Objective: To compare the transpalpebral and the transciliary variants of the SOC with regard to their potential role in aneurysm surgery.

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