Other Nerve Sheath Tumors of Brain and Spinal Cord.

The three main types of nerve sheath tumors are schwannomas, neurofibromas and perineuriomas. Multiple neurofibromas throughout the body are the hallmark of Neurofibromatosis type 1 (NF1). Spinal nerve sheath tumors are classified in the group of intradural extramedullary spinal cord tumors, in which they are the most common type (25-30%). Their incidence is 3-4 per 1 million people. Spinal schwannomas are encountered sporadically or in the context of Neurofibromatosis type 2, while neurofibromas are typical for patients with Neurofibromatosis type 1. Neurofibromas are composed predominantly of Schwann cells and fibroblasts, alongside which are also found axons, perineurial cells, mast cells and extracellular matrix. Most of the neurofibromas are asymptomatic. Any increase in the size of a neurofibroma or the presence of pain is an indicator of a possible malignant degeneration. Neurofibromas are treated surgically. Neurofibromas involve the whole nerve and cause its fusiform enlargement which makes it impossible to preserve the nerve's functions if complete tumor removal is performed. Hence, such tumors are initially observed. In case of progressive growth, the options are either resection of the tumor and immediate reconstruction with a peripheral nerve graft (e.g., nerve suralis interposition graft) or subtotal removal and follow-up. Malignant peripheral nerve sheath tumors (MPNST) are very rare tumors with incidence of around 1 per 1,000,000 people. MPNST account for 3-10% of all soft-tissue sarcomas. The most common initial symptom of MPNST is a painless mass. Any rapid increase in a subcutaneous mass or rapid onset of symptoms should raise the suspicion of a malignant tumor. In patients with diagnosed NF1, the recent rapid increase in a known lesion should raise the suspicion of malignant degeneration of the lesion and opt for active treatment. In the case of MPNST a wide surgical excision is advocated. The resectability depends greatly on the location of the tumors and varies from around 20% in paraspinal MPNST and reaches 95% in MPNST localized in the extremities. MPNST are a rare disease and should be managed by a multidisciplinary team of neurosurgeons, radiologists and oncologists.

Schwannomas of Brain and Spinal Cord.

Schwannomas are benign tumors originating from the Schwann cells of cranial or spinal nerves. The most common cranial schwannomas originate from the eight cranial nervevestibular schwannomas (VS). VS account for 6-8% of all intracranial tumors, 25-33% of the tumors localized in the posterior cranial fossa, and 80-94% of the tumors in the cerebellopontine angle (CPA). Schwannomas of other cranial nerves/trigeminal, facial, and schwannomas of the lower cranial nerves/are much less frequent. According to the World Health Organization (WHO), intracranial and intraspinal schwannomas are classified as Grade I. Some VS are found incidentally, but most present with hearing loss (95%), tinnitus (63%), disequilibrium (61%), or headache (32%). The neurological symptoms of VSs are mainly due to compression on the surrounding structures, such as the cranial nerves and vessels, or the brainstem. The gold standard for the imaging diagnosis of VS is MRI scan. The optimal management of VSs remains controversial. There are three main management options-conservative treatment or "watch-and-wait" policy, surgical treatment, and radiotherapy in all its variations. Currently, surgery of VS is not merely a life-saving procedure. The functional outcome of surgery and the quality of life become issues of major importance. The most appropriate surgical approach for each patient should be considered according to some criteria including indications, risk-benefit ratio, and prognosis of each patient. The approaches to the CPA and VS removal are generally divided in posterior and lateral. The retrosigmoid suboccipital approach is a safe and simple approach, and it is favored for VS surgery in most neurosurgical centers. Radiosurgery is becoming more and more available nowadays and is established as one of the main treatment modalities in VS management. Radiosurgery (SRS) is performed with either Gamma knife, Cyber knife, or linear accelerator. Larger tumors are being increasingly frequently managed with combined surgery and radiosurgery. The main goal of VS management is preservation of neurological function - facial nerve function, hearing, etc. The reported recurrence rate after microsurgical tumor removal is 0.5-5%. Postoperative follow-up imaging is essential to diagnose any recurrence.

Global Impact of the COVID-19 Pandemic on Cerebral Venous Thrombosis and Mortality.

BACKGROUND AND PURPOSE: Recent studies suggested an increased incidence of cerebral venous thrombosis (CVT) during the coronavirus disease 2019 (COVID-19) pandemic. We evaluated the volume of CVT hospitalization and in-hospital mortality during the 1st year of the COVID-19 pandemic compared to the preceding year. METHODS: We conducted a cross-sectional retrospective study of 171 stroke centers from 49 countries. We recorded COVID-19 admission volumes, CVT hospitalization, and CVT in-hospital mortality from January 1, 2019, to May 31, 2021. CVT diagnoses were identified by International Classification of Disease-10 (ICD-10) codes or stroke databases. We additionally sought to compare the same metrics in the first 5 months of 2021 compared to the corresponding months in 2019 and 2020 (ClinicalTrials.gov Identifier: NCT04934020). RESULTS: There were 2,313 CVT admissions across the 1-year pre-pandemic (2019) and pandemic year (2020); no differences in CVT volume or CVT mortality were observed. During the first 5 months of 2021, there was an increase in CVT volumes compared to 2019 (27.5%; 95% confidence interval [CI], 24.2 to 32.0; P<0.0001) and 2020 (41.4%; 95% CI, 37.0 to 46.0; P<0.0001). A COVID-19 diagnosis was present in 7.6% (132/1,738) of CVT hospitalizations. CVT was present in 0.04% (103/292,080) of COVID-19 hospitalizations. During the first pandemic year, CVT mortality was higher in patients who were COVID positive compared to COVID negative patients (8/53 [15.0%] vs. 41/910 [4.5%], P=0.004). There was an increase in CVT mortality during the first 5 months of pandemic years 2020 and 2021 compared to the first 5 months of the pre-pandemic year 2019 (2019 vs. 2020: 2.26% vs. 4.74%, P=0.05; 2019 vs. 2021: 2.26% vs. 4.99%, P=0.03). In the first 5 months of 2021, there were 26 cases of vaccine-induced immune thrombotic thrombocytopenia (VITT), resulting in six deaths. CONCLUSIONS: During the 1st year of the COVID-19 pandemic, CVT hospitalization volume and CVT in-hospital mortality did not change compared to the prior year. COVID-19 diagnosis was associated with higher CVT in-hospital mortality. During the first 5 months of 2021, there was an increase in CVT hospitalization volume and increase in CVT-related mortality, partially attributable to VITT.