Trochlear Schwannoma Research Articles

Trochlear nerve schwannoma with concomitant osimertinib-responsive stage IV lung adenocarcinoma: illustrative case.

The prognosis for cancer patients has been improved because of the development of molecularly targeted drugs. Treatment of intracranial tumors must be personalized while prioritizing the treatment of comorbid cancers. A 38-year-old man presented with bloody sputum, bilateral multiple nodules, and a mass in the lower lobe of his right lung. Bronchoscopy revealed stage IV lung adenocarcinoma with an epidermal growth factor receptor (EGFR) mutation. Screening head magnetic resonance imaging revealed a 38-mm-diameter mass in the left petroclival area. Because the patient was neurologically intact, the treatment of lung adenocarcinoma was prioritized, and the third-generation EGFR-tyrosine kinase inhibitor osimertinib was used. Although nodules in the lung began to shrink, the intracranial lesion expanded and caused hydrocephalus, necessitating a ventriculoperitoneal shunt. The tumor also caused diplopia, dysarthria, and gait abnormalities. A left anterior transpetrosal approach was used to remove the tumor derived from the trochlear nerve. The pathological examination revealed schwannoma. Neurological symptoms improved following surgery. Osimertinib was continued during the perioperative period. Osimertinib was effective for lung adenocarcinoma but not for trochlear nerve schwannoma, which required surgical intervention. It is necessary to tailor the treatment of benign brain tumors in patients with concurrent malignant cancers. https://thejns.org/doi/10.3171/CASE24144.

Isolated Superior Oblique Palsies Secondary to Trochlear Schwannomas in the Absence of Systemic Neurofibromatosis (P5-10.005)

Isolated Superior Oblique Palsies Secondary to Trochlear Schwannomas in the Absence of Systemic Neurofibromatosis (P5-10.005)

Brain Stem and Para-Brain Stem Lesions

Surgeries for brainstem lesions and adjacent areas needs meticulous manipulation in the profoundly deep surgical field. Moreover, it is associated with a high risk of complications pertinent to resection. The opportunity for a surgeon to amass extensive surgical experience in these lesions is limited. Additionally, the reduced tissue mobility in the brainstem, compared to other lesions, makes selecting the optimal surgical approach critical. Preoperative simulation is pivotal in surmounting these challenges. However, the limitations of preoperative simulations should be recognized in accurately depicting diminutive vessels and cranial nerves around the brainstem. Incorporating intraoperative anatomical observations and data from intraoperative monitoring into a surgical strategy is imperative. Here, we present three cases in which we believe preoperative simulation was effective; a cavernous hemangioma of the brainstem, trochlear schwannoma, and diffuse midline glioma in the pons.

Letter to the Editor Regarding “Surgical Treatment of Trochlear Nerve Schwannomas: Case Series and Systematic Review”

Letter to the Editor Regarding “Surgical Treatment of Trochlear Nerve Schwannomas: Case Series and Systematic Review”

Surgical Treatment of Trochlear Nerve Schwannomas: Case Series and Systematic Review

Cranial nerve schwannomas almost always arise from sensory or mixed nerves. Motor cranial nerves, such as the trochlear nerve, are rarely associated with schwannomas. No consensus has yet been made for surgical intervention because of the low number of reported cases of trochlear nerve schwannomas. This study comprises a systematic review of the literature and our experience for surgically treated trochlear nerve schwannomas. Three databases (Web of Science, PubMed, and Cochrane Library) were searched without date restrictions. Studies were included if they were published in the English literature and presented patients of any age who underwent surgical treatment for trochlear schwannoma. Data extracted from the included studies were combined with our experience. Forty-one studies, presenting 43 patients, met the inclusion criteria. The total number of patients was 45 after our experience was added. The most common symptoms were diplopia (62.2%), headache (46.7%), and motor weakness (37.8%). Mean age during the diagnosis was 45.1 years. Although the subtemporal transtentorial approach (n= 14) is the most preferred method, its application has decreased in recent years. In the last decade, the lateral suboccipital approach (n= 11) has gained popularity. Residual postoperative trochlear nerve deficit was detected in 81% of patients. The probability of neurologic deficit was not statistically associated with tumor volume (P= 0.914), location (P= 0.669), or resection rate (P= 0.554). Although trochlear schwannomas are rare and their treatment involves challenges, total resection with the proper approach provides the most desirable results.

A Trochlear Nerve Schwannoma with Spindle Cells detected by Cerebrospinal Fluid Cytology following Severe Hydrocephalus : A Case Report and Literature Review

急速に進行する視力障害で発症した37歳男性. CTおよびMRIにて重度の水頭症と脳底槽左側に境界明瞭な腫瘍性病変を認めた. 入院後, 緊急脳室ドレナージを行い, 後日, 脳室-腹腔シャント留置術と開頭腫瘍摘出術を施行した. 腫瘍は左滑車神経より発生しており, 病理組織診断より神経鞘腫と診断された. 術前の髄液検査ではタンパク濃度の上昇を認め, さらに髄液細胞診にて腫瘍の一部と考えられるspindle cellが多数検出された. 神経鞘腫に水頭症が併発する原因として, これらが関与していた可能性がある.

Vertical Comitance of Hypertropia in Congenital and Acquired Superior Oblique Palsy.

Ivanir and Trobe have claimed that hypertropia (HT) that is greater in upgaze than downgaze, or equal to it, is characteristic of decompensated congenital superior oblique (SO) palsy and never present in ischemic, traumatic, or tumorous SO palsy. The reliability of this claim was tested in patients with SO palsy confirmed by MRI demonstration of subnormal ipsilesional SO size. Quasi-coronal, surface coil MRI was performed in target-controlled central gaze to identify patients with a unilateral reduction in SO cross section indicative of palsy. Nine patients gave an unequivocal history or had markedly increased vertical fusional amplitudes indicative of congenital onset (mean age 38 ± 16 years, SD). Seven patients had unequivocal acquired onset (age 47 ± 14 years and symptom duration 5.4 ± 4.8 years), including 2 with demonstrated trochlear Schwannoma and 5 with onset after severe head trauma. Fifteen patients had gradually progressive onset unequivocally not congenital yet not associated with any identifiable precipitating event (age 52 ± 20 years and symptom duration 13 ± 14 years). Maximum SO cross section averaged 8.6 ± 3.9 mm2 in congenital palsy, not significantly different from 11.3 ± 3.5 mm2 in acquired palsy (P = 0.08) either unequivocally or progressively acquired, but significantly less than about 19 mm2 contralesionally in SO palsy (P < 10-4). Although mean central gaze HT was greater at 20.6 ± 8.0Δ in 9 cases of congenital than that in 22 acquired cases at 11.4 ± 6.8Δ (P = 0.002), HT was 8.4 ± 16.3Δ less in upgaze than downgaze in congenital SO palsy and 3.7 ± 11.2Δ less in acquired SO palsy. In congenital palsy, 33% of patients had HT greater in upgaze than downgaze while in 67% HT was greater in downgaze (by up to 42Δ). In acquired SO palsy, HT was greater in upgaze than downgaze or equal to it in 8 cases (36%, P = 0.87, X2). In acquired SO palsy, HT was greater in upgaze than downgaze in 37% and greater in downgaze than upgaze in 59% of cases. The HT was equal in upgaze and centralgaze in no congenital and 3 acquired cases of SO palsy. Trends were similar in unequivocal acquired and progressive acquired (noncongenital) SO palsy (P > 0.4). Hypertropia is not characteristically greater in upgaze than downgaze in congenital SO palsy proven by SO atrophy on MRI. In fact, average HT is greater in downgaze than upgaze in both acquired and congenital palsy, sometimes strikingly so in the latter. The finding of HT greater in upgaze than downgaze, or equal to it, does not reliably indicate that SO palsy is congenital, nor does maximum SO cross section.

In Reply to the Letter to the Editor Regarding “Two-Dimensional Video of Surgery on Trochlear Schwannoma”

In Reply to the Letter to the Editor Regarding “Two-Dimensional Video of Surgery on Trochlear Schwannoma”

Letter to the Editor Regarding “Two-Dimensional Video of Surgery on Trochlear Schwannoma”

Letter to the Editor Regarding “Two-Dimensional Video of Surgery on Trochlear Schwannoma”

Teaching NeuroImages: Trochlear nerve schwannoma

A 54-year-old woman presented for evaluation of binocular vertical diplopia worse in downgaze. She had limited infraduction of the right eye in adduction and a right hypertropia worse in left gaze and right head tilt, consistent with a right trochlear nerve palsy. MRI brain revealed enlargement and enhancement of the right trochlear nerve in the subarachnoid space (figure). Laboratory testing and CSF analysis were normal. The imaging findings were stable over several years, suggesting the diagnosis of a trochlear nerve schwannoma.

Trochlear Schwannoma Presenting as Trigeminal Neuralgia

Trochlear Schwannoma Presenting as Trigeminal Neuralgia

Trochlear Nerve Schwannoma With Repeated Intratumoral Hemorrhage

Trochlear nerve schwannoma is extremely rare, with only 35 pathologically confirmed patients being reported in the literature. Here, the authors report a patient of trochlear nerve schwannoma in the prepontine cistern manifesting as facial pain and double vision and presenting the image characteristics of repeated intratumoral hemorrhage, which has never been reported in the literature. Total tumor along with a portion of the trochlear nerve was removed by using a retrosigmoid approach. Facial pain disappeared after operation, and the diplopia remained. Follow-up studies have shown no tumor recurrence for 2 years and the simultaneous alleviation of diplopia. Information regarding the clinical presentation, radiological features and surgical outcomes of trochlear nerve schwannoma are discussed and reviewed in the paper.

Isolated schwannoma involving extraocular muscles

Progressive strabismus initially considered idiopathic may be caused by isolated schwannomas of motor nerves to extraocular muscles, detectable only on careful imaging. This study reviewed clinical experience of a referral practice in identifying schwannomas on magnetic resonance imaging (MRI). We reviewed 647 cases imaged for strabismus to identify presumed cranial nerve schwannomas, identified by gadodiamide-enhanced, high-resolution surface coil orbital MRI and thin-section cranial MRI. Clinical features and management were correlated with MRI. Schwannomas were identified as fusiform intraneural enlargements in 8 cases: 1 affecting the trochlear nerve; 2, the abducens nerve; and 5 the oculomotor nerve. Involved muscles were atrophic. Both abducens schwannomas, 1 superior oblique, and 1 oculomotor schwannoma were subarachnoid; 3 were intraorbital, and bilateral oculomotor lesions of 1 case extended from cavernous sinus to orbit. Associated strabismus progressed for 3-17years. Abducens schwannoma caused esotropia; trochlear schwannoma caused hypertropia and cyclotropia. Intracranial oculomotor schwannoma caused mydriasis and exotropia. Intraorbital schwannoma caused exotropia with or without hypertropia. Since lesion diameters were 3-9mm, 6 had been previously missed on routine MRI. Progressive, acquired strabismus may be caused by isolated cranial nerve schwannomas, representing about 1% of strabismus cases in this study, involving the oculomotor more than abducens nerve. Because most schwannomas are small and deep in the orbit, findings could be readily missed by routine imaging, leading to a possible diagnosis of idiopathic strabismus. Schwannomas should be suspected when extraocular muscles are atrophic, but the causative lesions themselves are identifiable only using targeted, high resolution MRI.

An unusual cause of trochlear nerve palsy and brainstem compression

Schwannoma originates from the Schwann cells at the Obersteiner-Redlich zone, which marks the junction of central and peripheral myelin of the cranial nerves. Most frequently affected are the vestibular, trigeminal, and facial nerves followed by the lower cranial nerves. Trochlear schwannoma in the absence of neurofibromatosis is a rare entity. The purpose of this report is to serve as a reminder to consider trochlear nerve schwannoma in the list of differential diagnosis of such tumors as the outcome is far better than the intraaxial tumor in that location.

A Case of Trochlear Nerve Schwannoma Presenting with Binocular Diplopia

A Case of Trochlear Nerve Schwannoma Presenting with Binocular Diplopia

Isolated trochlear nerve schwannoma presenting with diplopia: A case report and literature review

Abstract Background Trochlear nerve schwannoma is a very rare tumor encountered especially in patients without type 2 neurofibromatosis (NF2). Most of the time, this tumor is diagnosed intraoperatively. We describe a rare case of trochlear nerve schwannoma. Clinical Presentation A 63-year-old male presented with generalized headache from 8 months earlier, without nausea and vomiting. The headache had worsened during the last months. Clinically, he suffered from transient diplopia. Magnetic resonance imaging (MRI) demonstrated a mass in the left ambient and interpeduncular cisterns that was compressing the midbrain and upper pons. The preoperative impression was of trigeminal schwannoma. However, intraoperatively, the tumor originated in the trochlear nerve. The mass was removed entirely via left suboccipital retrosigmoid approach. The histopathology diagnosis confirmed schwannoma. The patient's diplopia did not improve postoperatively. Conclusion Trochlear nerve schwannoma is a rare type of schwannoma and in almost all of the cases is diagnosed intraoperatively. There are three types of trochlear nerve schwannoma according to the classification proposed for trigeminal schwannoma: cisternal type—confined to the precavernous segment of the trochlear nerve; cistocavernous type—invading the cavernous sinus and the retroclival and retropetrosal cistern; cavernous type—located in the middle cranial fossa on the cavernous or paracavernous segment of the fourth cranial nerves, with or without cavernous sinus invasion. The cisternal type was the most common type encountered in previous studies. The clinical signs and symptoms of trochlear nerve schwannoma are similar to the trigeminal schwannoma and should be considered in the differential diagnosis of trigeminal schwannoma.

Intracranial nonvestibular neurinomas: Young neurosurgeons’ experience

ABSTRACT Background and Objectives: Neurinoma arising from other than nonvestibular cranial nerves is less prevalent. Here we present our experiences regarding the clinical profile, investigations, microneurosurgical management, and the outcome of nonvestibular cranial nerve neurinomas. Materials and Methods: From January 2005 to December 2011, the recorded documents of operated nonvestibular intracranial neurinomas were retrospectively studied for clinical profile, investigations, microneurosurgical management, complications, follow-up, and outcomes. Results: The average follow-up was 24.5 months. Total number of cases was 30, with age ranging from 9 to 60 years. Sixteen cases were males and 14 were females. Nonvestibular cranial nerve schwannomas most commonly originated from trigeminal nerve followed by glossopharyngeal+/vagus nerve. There were three abducent nerve schwannomas that are very rare. There was no trochlear nerve schwannoma. Two glossopharyngeal+/vagus nerve schwannomas extended into the neck through jugular foramen and one extended into the upper cervical spinal canal. Involved nerve dysfunction was a common clinical feature except in trigeminal neurinomas where facial pain was a common feature. Aiming for no new neurodeficit, total resection of the tumor was done in 24 cases, and near-total resection or gross total resection or subtotal resection was done in 6 cases. Preoperative symptoms improved or disappeared in 25 cases. New persistent deficit occurred in 3 cases. Two patients died postoperatively. There was no recurrence of tumor till the last follow-up. Conclusion: Nonvestibular schwannomas are far less common, but curable benign lesions. Surgical approach to the skull base and craniovertebral junction is a often complex and lengthy procedure associated with chances of significant morbidity. But early diagnosis, proper investigations, and evaluation, along with appropriate decision making and surgical planning with microsurgical techniques are the essential factors that can result in optimum outcome.

Intracranial nonvestibular neurinomas: Young neurosurgeons' experience.

Background and Objectives:Neurinoma arising from other than nonvestibular cranial nerves is less prevalent. Here we present our experiences regarding the clinical profile, investigations, microneurosurgical management, and the outcome of nonvestibular cranial nerve neurinomas.Materials and Methods:From January 2005 to December 2011, the recorded documents of operated nonvestibular intracranial neurinomas were retrospectively studied for clinical profile, investigations, microneurosurgical management, complications, follow-up, and outcomes.Results:The average follow-up was 24.5 months. Total number of cases was 30, with age ranging from 9 to 60 years. Sixteen cases were males and 14 were females. Nonvestibular cranial nerve schwannomas most commonly originated from trigeminal nerve followed by glossopharyngeal+/vagus nerve. There were three abducent nerve schwannomas that are very rare. There was no trochlear nerve schwannoma. Two glossopharyngeal+/vagus nerve schwannomas extended into the neck through jugular foramen and one extended into the upper cervical spinal canal. Involved nerve dysfunction was a common clinical feature except in trigeminal neurinomas where facial pain was a common feature. Aiming for no new neurodeficit, total resection of the tumor was done in 24 cases, and near-total resection or gross total resection or subtotal resection was done in 6 cases. Preoperative symptoms improved or disappeared in 25 cases. New persistent deficit occurred in 3 cases. Two patients died postoperatively. There was no recurrence of tumor till the last follow-up.Conclusion:Nonvestibular schwannomas are far less common, but curable benign lesions. Surgical approach to the skull base and craniovertebral junction is a often complex and lengthy procedure associated with chances of significant morbidity. But early diagnosis, proper investigations, and evaluation, along with appropriate decision making and surgical planning with microsurgical techniques are the essential factors that can result in optimum outcome.

The Middle Fossa Approach for the Removal of a Trochlear Schwannoma

Objectives. Schwannomas originating from the trochlear nerve are extremely rare; only 30 cases have been reported in the literature. Many operative approaches have been utilized for lesion resection, but the advantages of the anterior transpetrosal approach are numerous and include excellent exposure, minimal extradural retraction of the temporal lobe, and minimal cerebrospinal fluid leaks. We report the second case of a trochlear schwannoma resected via the anterior transpetrosal approach. Setting. A 64-year-old male presented with 3-month history of diplopia and headaches. On physical examination, he was found to have a right fourth nerve palsy. Brain magnetic resonance imaging revealed a mass within the right ambient cistern compressing the adjacent midbrain. A right-sided anterior transpetrosal approach was used—which confirmed that the trochlear nerve entered the mass—to achieve gross total resection. Pathological examination confirmed diagnosis of schwannoma. The patient was discharged on postoperative day 3. He experienced a persistent fourth nerve palsy postoperatively with an otherwise normal neurological examination. Follow-up imaging confirmed complete removal of the tumor. Conclusion. The anterior transpetrosal approach is an excellent approach for removal of trochlear schwannomas involving the cisternal course of the trochlear nerve. It affords complete visualization of this anatomical region while introducing minimal morbidity.

Posterior Cavernous Anterior Transpetrosal Posteromedial Rhomboid (Dolenc-Kawase Rhomboid) Approach to Posterior Cavernous and Petroclival Lesions

The anterior transpetrosal approach involves extradural exposure of the posteromedial (Kawase) triangle, which is bounded by the arcuate eminence, the greater superficial petrosal nerve (GSPN), and the petrous ridge. It allows exposure of the tentorium and the middle fossa and the posterior fossa up to the internal auditory meatus. Despite permitting a key access point, the exposure is conical and crowded; it does not allow proper exposure to the Vth nerve. Exiting is from the tentorium, the VIth nerve in the Dorello canal, and the undersurface of the attachment of the tentorium to the posterior clinoid process. Dissection of the posterior cavernous sinus wall over the V2, V3, and gasserian ganglion permits access to a posteromedial rhomboid bounded by the arcuate eminence (posterior), GSPN (lateral), the petrous ridge (medial) and V3, and the gasserian ganglion (anterior). Ligation and division of the superior petrosal sinus close to the posterior clinoid process and gentle elevation of the Vth nerve root permit an enlarged view of the previous inaccessible areas. A posterior cavernous anterior transpetrosal posteromedial rhomboid (Dolenc-Kawase rhomboid) approach with or without zygomatic osteotomy was used in the treatment of petroclival meningiomas (32); giant dumbell trigeminal schwannoma (11); clival chordoma (6); clival chondrosarcoma (4); trochlear schwannoma (1); giant posterior fossa craniopharyngioma (4); middle + posterior fossa epidermoid (2); hypothalamic hamartoma (1); giant low basilar bifurcation aneurysm (2); petroclival hemangiopericytoma (1); and bilateral petroclival, cavernous, and tentorial histiocytosis (Rosai-Dorfman).