Gamma knife radiosurgery for trigeminal schwannomas: A systematic review and meta-analysis.

BACKGROUND: Gamma knife radiosurgery (GKRS) has been deemed as the gold standard stereotactic radiosurgery (SRS) mode for the treatment of intracranial tumors, cerebrovascular diseases and brain functional diseases. Our study was aimed to systematically evaluate the efficacy, safety, and complications of gamma knife radiosurgery for trigeminal schwannomas. METHOD: We performed a systematic review and meta-analysis to analyze the clinical outcomes of patients with trigeminal schwannomas treated primarily or adjunctly with GKRS. We searched two databases, Pubmed and Embase, for studies published before January 1, 2021, using GKRS for trigeminal schwannomas. Studies reporting treatment of other schwannomas, or other forms of SRS such as linear accelerator and Cyberknife were excluded to reduce its heterogeneity. RESULTS: Our search achieved 351 studies, of which 35 were assessed for full-text eligibility. 19 studies were included in the meta-analysis. 456 of 504 patients (0.94, 95% CI 0.91-0.96, I2 = 3.02%, p < 0.01) from 18 studies had local control, and 278 of 489 patients (0.63, 95%CI 0.48-0.78, I2 = 88.75%, p < 0.01) from 16 studies experienced tumor regression or disappearance. 231 of 499 patients (0.50, 95% CI 0.37-0.62; I2 = 83.89%, P < 0.01) from 17 studies had clinical symptoms improved. There was no significant difference in tumor control between those treated with GKRS as either primary treatment or adjuvant to surgery(p = 0.390). CONCLUSION: GKRS is an efficacious primary and adjuvant method of treating trigeminal schwannomas, with reliable tumor control rates. Randomized controlled trials are needed to further and comprehensively evaluate the benefit-to-risk ratio of gamma knife radiosurgery.

Multiple cranial nerve schwannomas and meningiomas as a hallmark sign of neurofibromatosis type 2 in a child.

Halefoglu AM. Multiple cranial nerve schwannomas and meningiomas as a hallmark sign of neurofibromatosis type 2 in a child. Turk J Pediatr 2018; 60: 107-110. Neurofibromatosis type 2 is a rarely encountered autosomal dominant disorder manifesting with typical radiological findings. These patients have a predilection for development of benign tumors in the central nervous system. Although the presenting symptom is most commonly hearing loss due to acoustic schwannomas, symptoms emanating from other cranial tumors are not uncommon. Herein, we described a 16-year-old male patient presented with multiple meningiomas and cranial nerve schwannomas revealed by magnetic resonance imaging. He fulfilled the diagnostic criteria of neurofibromatosis type 2 and underwent treatment. We emphasized the role of radiology in the early diagnosis of this inherited disorder in order to provide a better prognosis.

Combined isolated trigeminal and facial neuropathies from perineural invasion by squamous cell carcinoma: A case series and review of the literature.

Perineural invasion is a targeted cellular proliferation guided by neurotrophins, rather than a simple diffusion of tumor in a path of least resistance. Invasion of cranial nerves by squamous cell carcinoma can represent an important diagnostic dilemma. It commonly presents as a distinct clinical neurological syndrome of combined isolated trigeminal and facial neuropathies. The focal cancer source may have been overlooked or remain occult. This case series illustrates diverse clinical presentations and neuroimaging challenges in four patients with squamous cell carcinoma of the cranial nerves. Anatomical pathways linking the trigeminal and facial nerves are reviewed, with emphasis on the auriculotemporal and pterygopalatine nerves. A successful neuroimaging strategy requires a targeted multimodality analysis of specific anatomical loci at the base of the skull. Attention must be directed to subtle radiological findings, such as obliteration of fat planes and linear enhancement along nerve branches, rather than bulky tumor tissue or bony invasion. Despite advances in microsurgical dissection and targeted radiotherapy, recovery of established neuropathic deficits is not expected. The prognosis remains poor in cases of advanced disease, emphasizing the importance early diagnosis by clinical acumen and focused neuroimaging.

Rare case of radiation-induced trigeminal schwannoma occurring in a long-term glioblastoma multiforme survivor.

Glioblastoma multiforme (GBM) is a high-grade primary brain tumour with a notably poor prognosis. Research demonstrates a median survival of just over 1 year following aggressive treatment. Long-term survival is notably rare. Cranial radiotherapy and postexcisional prophylactic treatment is associated with the development of second, histologically distinct tumours in rare cases. Radiation-induced intracranial schwannomas are uncommon, with only a small number of cranial nerve schwannoma cases reported in recent decades. To our knowledge, this is the first reported case of a radiation-induced benign trigeminal schwannoma occurring following long-term survival from glioblastoma. Here we present (1) a rare case of 14-year survival following treatment of a right parietal glioblastoma and the development of a radiation-induced benign trigeminal schwannoma in a 35-year-old man, and (2) a review of radiation-induced schwannoma cases reported in the existing literature.

Malignant peripheral nerve sheath tumors of the eighth cranial nerve arising without prior irradiation.

OBJECTIVE Malignant peripheral nerve sheath tumors (MPNSTs) of the eighth cranial nerve (CN) are exceedingly rare. To date the literature has focused on MPNSTs occurring after radiation therapy for presumed benign vestibular schwannomas (VSs), while MPNSTs arising without prior irradiation have received little attention. The objectives of the current study are to characterize the epidemiology, clinical presentation, disease course, and outcome using a large national cancer registry database and a systematic review of the English literature. Additionally, a previously unreported case is presented. METHODS The authors conducted an analysis of the Surveillance, Epidemiology, and End Results (SEER) database, a systematic review of the literature, and present a case report. Data from all patients identified in the SEER database with a diagnosis of MPNST involving the eighth CN, without a history of prior radiation, were analyzed. Additionally, all cases reported in the English literature between January 1980 and March 2015 were reviewed. Finally, 1 previously unreported case is presented. RESULTS The SEER registries identified 30 cases between 1992 and 2012. The average incidence was 0.017 per 1 million persons per year (range 0.000-0.0687 per year). The median age at diagnosis was 55 years, and 16 (53%) were women. Thirteen cases were diagnosed upon autopsy. Of the 17 cases diagnosed while alive, the median follow-up was 118 days, with 3 deaths (18%) observed. When compared with the incidence of benign VS, 1041 VSs present for every 1 MPNST arising from the eighth CN. Including a previously unreported case from the authors' center, a systematic review of the English literature yielded 24 reports. The median age at diagnosis was 44 years, 50% were women, and the median tumor size at diagnosis was 3 cm. Eleven patients (46%) reported isolated audiovestibular complaints typical for VS while 13 (54%) exhibited facial paresis or other signs of a more aggressive process. Treatment included microsurgery alone, microsurgery with adjuvant radiation, or microsurgery with chemoradiation. Sixty-one percent of patients receiving treatment experienced recurrence, 22% of which were diagnosed with drop metastases to the spine. Ultimately, 13 patients (54%) died of progressive disease at a median of 3 months following diagnosis. The ability to achieve gross-total resection was the only feature that was associated with improved disease-specific survival. CONCLUSIONS MPNSTs of the eighth CN are extremely rare and portend a poor prognosis. Nearly half of patients initially present with findings consistent with a benign VS, often making an early diagnosis challenging. In light of these data, early radiological and clinical follow-up should be considered in those who elect nonoperative treatment, particularly in patients with a short duration of symptoms or atypical presentation. These data also provide a baseline rate of malignancy that should be considered when estimating the risk of malignant transformation following stereotactic radiosurgery for VS.

Effect of local application of an antibody against brain-derived neurotrophic factor on neuroma formation after transection of the inferior alveolar nerve in the rat.

This study aimed to examine the contributions of brain-derived neurotrophic factor (BDNF) at the injury site toward neuroma formation and nerve regeneration after inferior alveolar nerve transection. Histological analysis confirmed neuroma formation at 2 weeks after complete transection of the inferior alveolar nerve. A local administration of an antibody to BDNF inhibited connective tissue proliferation at the injury site and promoted nerve fiber integrity. Fluorogold labeling showed a significantly higher number of labeled cells in the trigeminal ganglion in the anti-BDNF-treated group compared with the vehicle control group. In-situ hybridization histochemistry showed intense signals for tropomyosin receptor kinase B mRNA in the area of the injury site containing fibrous or granular tissue in the anti-BDNF-treated group. In contrast, these signals were close to the detection limit in the area of the perineurium in intact nerve trunks, indicating that the signals were expressed by fibroblasts within the connective tissue. These findings suggest that antagonization of endogenous BDNF induced by nerve injury reduces neuroma formation, without inhibiting damaged axon regeneration.

Intratemporal traumatic neuromas of the facial nerve: evidence for multiple etiologies.

OBJECTIVE: To describe 2 patients with traumatic neuromas of the intratemporal facial nerve in the absence of trauma. STUDY DESIGN: Retrospective case review. SETTING: Tertiary care referral center. PATIENTS: Patients included underwent resection of an intratemporal facial nerve mass. Upon pathologic evaluation, the patients were found to have traumatic neuromas of the facial nerve. INTERVENTION(S): Patients underwent resection of an intratemporal facial traumatic neuroma. Histopathologic evaluation was performed including an immunohistochemistry evaluation. RESULTS: Two patients were identified with intratemporal facial nerve traumatic neuromas. The patients had no significant history of trauma or chronic inflammatory process. Pathologic evaluations, including immunohistochemistry, of the excised masses were consistent with traumatic neuromas. All tumors were noted to have a disorganized collection of axons and were not consistent with the expected diagnosis of schwannoma. Tumors involved the tympanic and vertical segments of the facial nerve. A cavernous angioma was found within one mass and is thought to be the etiology of neuroma formation. CONCLUSION: Traumatic neuromas are possible in the intratemporal facial nerve in the absence of trauma. A cavernous angioma of the facial nerve is a newly described possible cause of traumatic neuroma formation.

Treatment of recurrent lingual nerve end-neuroma: A case report.

A neuroma is a collection of disorganized nerve sprouts emanating from an interruption of axonal continuity, forming within a collagen scar as the nerve attempts to regenerate. Lingual neuroma formation secondary to iatrogenic trauma to the tongue is likely not uncommon; however, we could not find a report in the literature of treatment of a distal tongue end-neuroma treated by resection and implantation into muscle. Here we describe a patient who experienced debilitating chronic tongue pain after excision of a benign mass. After failing conservative management, the patient was taken to the operating room where an end-neuroma of the lingual nerve was identified and successfully treated by excision and burying of the free proximal stump in the mylohyoid muscle. At 17 months postoperatively, she remains pain free without dysesthesias.

Solitary giant neurofibroma of the mental nerve: a trauma-related lesion?

Neurofibroma is a benign neoplasm derived from peripheral nerves whose etiology is still unclear. It may present as a solitary lesion or be associated with other diseases such as neurofibromatosis type I and II syndrome. This paper aims to report an extremely rare case of a solitary giant neurofibroma of the mental nerve whose etiology was related to a local trauma. A 14-year-old female patient presented an extensive left facial mass with a size of 7 × 5 × 4 cm, located between the teeth 33 and 37 in the mandible region. It has begun to grow 3 months after a local trauma. Imaging studies were suggestive of a soft-tissue lesion, with minimal bone changes and maintaining the integrity of the mandibular canal and mental foramen. Histopathological tests showed spindle cells with undulated and hyperchromatic nuclei, and sparse cytoplasm in a stroma composed of dense fibrous connective tissue. Immunohistochemistry revealed positive expression for the proteins S-100 and vimentin, confirming the diagnosis of neurofibroma. The patient underwent surgical removal of the lesion by intraoral approach and evolved with an excellent cosmetic result and no signs of recurrence after 2 years of follow up. We report a rare case of solitary giant neurofibroma whose etiology was related to a local trauma. To our knowledge, this is the first report of a mental nerve neurofibroma. Although the etiology remains unclear, we suggest the investigation of local trauma as a possible etiologic factor for solitary neurofibromas of the jaw.

Assessment of antiangiogenic effect of imatinib mesylate on vestibular schwannoma tumors using in vivo corneal angiogenesis assay.

OBJECT: Angiogenesis and the platelet-derived growth factor (PDGF) pathway are active in the pathogenesis of vestibular schwannomas (VSs). The purpose of this study was to test whether imatinib mesylate (Gleevec), a PDGF receptor (PDGFR) blocker, reduces angiogenic capacity in sporadic VS and in VS associated with neurofibromatosis Type 2 (NF2) using a corneal angiogenesis assay. METHODS: From 121 VS tissue samples stored in the tumor bank at the Marmara University Institute of Neurological Sciences, 10 samples (6 from sporadic cases, 4 from NF2-associated cases) were selected at random for use in this study. Expression of PDGF-A and PDGF-B and their receptors was evaluated in sporadic and NF2-associated VS as well as in glioblastoma (GBM) and normal brain tissue by means of immunohistochemistry and Western blot analysis. Corneal angiogenesis assay was then used to evaluate the angiogenic capacity of tissue specimens from sporadic and NF2-associated VS with and without imatinib treatment as well as positive and negative controls (GBM and normal brain tissue). RESULTS: The angiogenic potential of the sporadic and NF2-associated VS tumor tissue differed significantly from that of the positive and negative control tissues (p <0.05). Furthermore, NF2-associated VS showed significantly lower angiogenic potential than sporadic VS (p <0.05). Imatinib treatment significantly reduced the angiogenic potential in both the sporadic VS and the NF2-associated VS groups. The level of PDGF-A and PDGFR-α as well as PDGF-B and PDGFR-ß expression in sporadic VS and NF2-associated VS also differed significantly (p <0.05) from the levels in controls. Additionally the level of PDGFR-ß was significantly higher in sporadic VS than in NF2-associated VS (p <0.05). CONCLUSIONS: The findings of this study indicate that NF2-associated VS has significantly more angiogenic potential than sporadic VS and normal brain tissue. Additionally, imatinib reduces the angiogenic activity of both sporadic and NF2-associated VS. The authors conclude that imatinib may be a potential treatment for VS, especially for NF2-associated lesions that cannot be cured with resection or radiosurgery.

Dermoid cyst in the facial nerve--a unique diagnosis.

Facial nerve paralysis in children may occur as a complication of infections, trauma, or rarely from benign or malignant tumors of the facial nerve. We present the first reported case of a dermoid tumor in the facial nerve causing facial paralysis in a child. Case report at a tertiary Children's Hospital. A 9-month-old was referred to our institution for evaluation of persistent, complete right sided facial paralysis three months after receiving a diagnosis of Bell's palsy. A workup at our institution including MRI and CT revealed marked widening of the facial canal in the mastoid segment consistent with facial nerve schwannoma or hemangioma. Surgical exploration via mastoidectomy and facial nerve decompression revealed keratinous material containing hair that had fully eroded the facial nerve, disrupting it completely. The entire tumor was removed along with the involved segment of facial nerve, and the missing facial nerve segment was cable grafted. Histological examination of the tumor confirmed a ruptured dermoid cyst in the facial nerve. Facial nerve tumors are rare causes of facial paralysis in children, accounting for fewer than 10% of cases of facial paralysis in the pediatric population. Dermoid cyst can occur throughout the head and neck region in children, but a dermoid tumor in the facial nerve has not been described in the literature prior to this report. This represents a new and uncommon diagnostic entity in the evaluation of facial nerve paralysis in children. Appropriate imaging studies and pathology slides will be reviewed.

["An Italian Court recognizes the occupational origin of a trigeminal neuroma in a mobile telephone user: a case-study of the complex relationships between science and laws"]. / Una Corte italiana riconosce l'origine professionale di un neurinoma del trigemino in un utilizzatore di telefoni mobili: un esempio concreto dei complessi rapporti tra scienza e diritto.

BACKGROUND: Scientific knowledge is essential for the resolution of disputes in law and administrative applications (such as toxic tort litigation and workers' compensation) and provides essential input for public policy decisions. There are no socially agreed-upon rules for the application of this knowledge except in the law. On a practical level, the legal system lacks the ability to assess the validity of scientific knowledge that can be used as evidence and therefore relies heavily on expert opinion. A key issue is how to ensure that professionals in any field provide judges with sound advice, based on relevant and reliable scientific evidence. The search for solutions to this problem seems particularly urgent in Italy, a country where a number of unprecedented verdicts of guilt have been pronounced in trials involving personal injuries from exposure to electromagnetic fields. OBJECTIVES AND METHODS: An Italian Court has recently recognized the occupational origin of a trigeminal neuroma in a mobile telephone user, and ordered the Italian Workers' Compensation Authority (INAIL) to award the applicant compensation for a high degree (80%) of permanent disability. We describe and discuss the salient aspects of this sentence as a case-study in the framework of the use (and misuse) of scientific evidence in toxic-tort litigations. RESULTS: Based on the motivations of the verdict, it appears that the judge relied on seriously flawed expert testimonies. The "experts" who served in this particular trial were clearly inexperienced in forensic epidemiology in general, as well as in the topic at hand. Selective overviews of scientific evidence concerning cancer risks from mobile phone use were provided, along with misleading interpretations of findings from relevant epidemiologic studies (including the dismissal of the Interphone study results on the grounds of purported bias resulting from industry funding). The necessary requirements to proceed to causal inferences at individual level were not taken into account and inappropriate methods to derive estimates of personal risk were used. CONCLUSIONS: A comprehensive strategy to improve the quality of expert witness testimonies in legal proceedings and promote just and equitable verdicts is urgently needed in Italy. Contrary to other countries, such as the United States or the United Kingdom, legal standards for expert testimony, such as preliminary assessment of scientific evidence admissibility and qualification requirements for professionals acting as experts in the courtroom, are lacking in our country. In this and similar contexts, recommendations issued by professional associations (including EBEA and BEMS) could play a role of paramount importance. As examples, we refer to the guidelines recently endorsed by the UK General Medical Council and the American Academy of Pediatrics.

Long-term health experience of jet engine manufacturing workers: IV. A comparison of central nervous system cancer ascertainment using mortality and incidence data.

PURPOSE: To compare ascertainment of central nervous system (CNS) neoplasms with the use of mortality and incidence data as part of an occupational epidemiology study. METHODS: Deaths were identified by matching the cohort of 223,894 jet engine manufacturing employees to the U.S. Social Security Administration death files and the National Death Index. Incident cancer cases were identified by matching the cohort to 19 state cancer registries. RESULTS: We identified 718 cases overall: 59% by the use of both mortality and cancer incidence tracing; 24% by the use of only mortality tracing, and 17% by the use of only cancer incidence tracing. Compared with state cancer registries, death certificates missed 38% of the malignant, more than six times the benign and nearly 1.5 times the unspecified CNS cases. The positive predictive value of death certificates, with cancer registry as gold standard, was 6% for unspecified, 35% for benign, and 86% for malignant histologies. CONCLUSIONS: Death certificates seriously underascertained benign and unspecified CNS tumors; analyses determined with mortality data would not accurately capture the true extent of disease among the cohort. Most state cancer registries have only collected nonmalignant CNS tumor information since 2004, which currently limits the usefulness of state cancer registries as a source of nonmalignant CNS tumor identification. Underascertainment of CNS deaths could seriously affect interpretation of results, more so if examining nonmalignant CNS.

Traumatic facial nerve neuroma with facial palsy presenting in infancy.

OBJECTIVE: To describe the management of traumatic neuroma of the facial nerve in a child and literature review. PATIENT: Sixteen-month-old male subject. INTERVENTION: Radiological imaging and surgery. MAIN OUTCOME MEASURES: Facial nerve function. RESULTS: The patient presented at 16 months with a right facial palsy and was found to have a right facial nerve traumatic neuroma. A transmastoid, middle fossa resection of the right facial nerve lesion was undertaken with a successful facial nerve-to-hypoglossal nerve anastomosis. The facial palsy improved postoperatively. CONCLUSION: A traumatic neuroma should be considered in an infant who presents with facial palsy, even in the absence of an obvious history of trauma. The treatment of such lesion is complex in any age group but especially in young children. Symptoms, age, lesion size, growth rate, and facial nerve function determine the appropriate management.