Cerebellopontine Angle Lesions Research Articles

Applying the Full Endoscopic Keyhole Technique to CPA Lesions: A Single-Center Study.

In recent years, endoscopy has become an increasingly common tool used during neurosurgical procedures. However, its application in treating cerebellopontine angle (CPA) lesions has not progressed as rapidly. In this study, the authors present their initial experience with surgically treating CPA lesions using a fully endoscopic keyhole retrosigmoid approach. They conducted a retrospective analysis of clinical data from patients who underwent endoscopic keyhole CPA surgery at their center between May 2017 and April 2022. They provide a comprehensive explanation of this method and an overview of the strategies that have been developed to achieve better clinical outcomes. The study included 107 patients, consisting of 10 cases of vestibular schwannoma, 21 cases of epidermoid cyst, 32 cases of trigeminal neuralgia, and 44 cases of hemifacial spasm. The authors analyzed the clinicodemographic details of the patients. Among the 31 tumor cases, gross total resection was achieved in 25 patients (80.6%), while near-total resection was performed in 6 patients (19.4%). In patients with trigeminal neuralgia, facial pain resolved in 31 out of 32 patients (96.9%). Similarly, facial convulsions disappeared or were relieved in all 44 patients (100%) with hemifacial spasms after the operation. Postoperative complications included facial nerve paresis (n=9, 8.4%), with improvement observed in 6 cases during follow-up, transient facial hypoesthesia (n=3, 2.8%), cerebrospinal fluid rhinorrhea (n=3, 2.8%), transient abducens paresis (n=1, 0.9%), and postoperative hemorrhage (n=1, 0.9%). Endoscopy provides improved deep illumination and, combined with close-up observation, enhances the visualization of structures within the CPA region. The fully endoscopic keyhole technique is a safe and effective method for managing CPA lesions.

Case Report: Marfan’s Syndrome with Neurofibromatosis Type-2

Background Marfan’s syndrome (MFS) and neurofibromatosis type-2 (NF-2) are rare autosomal dominant diseases caused due to mutations in chromosome number 15 and 22, respectively. The chance of both the diseases occurring in the same patient is extremely rare. Case presentation In this report a rare case of a 16-year-old boy having a coexistence of both MFS and NF-2 is reported. The clinical findings consisted of musculoskeletal abnormalities consisting of laxity of joints, positive Steinberg thumb sign test, positive Walker-Murdoch wrist test, dolichostenomelia, and arachnodactyly. Anthropometric abnormalities reported an increase in lower segment height than the upper segment. Diagnostic assessment revealed pectus carinatum, multiple meningioma, and heterogeneous lesions in bilateral cerebellopontine angle that were ruled out as bilateral schwannoma confirming the diagnosis of MFS and NF-2. However, both must be regarded as novel mutations, and as the position of the two genes is unrelated, it is most probable that two different mutations have occurred. β-blocker was recommended as a prophylactic measure to minimize aortic root stiffness and control aortic root dilatation. Furthermore, surgery and radiation therapy were planned for the management of NF-2; however, the patient expressed skepticism regarding the course of treatment and follow-ups; as a result, this data was reported at the time of discharge with non-specified duration of follow-ups. Conclusions This case report demonstrates a rare case of MFS which is caused due to mutation in chromosome number 15 along with NF-2 which is caused due to mutation in chromosome number 22. Since the positions of the two genes are unrelated, it is concluded that two distinct mutations have occurred. As a result, this report highlights a rare coexistence of both mutations, which will benefit the medical profession in enhancing future studies.

Fully endoscopic microvascular decompression for hemifacial spasm: a clinical study and analysis

Fully endoscopic microvascular decompression (MVD) of the facial nerve is the main surgical treatment for hemifacial spasm. However, the technique presents distinct surgical challenges. We retrospectively analyzed prior cases to consolidate surgical insights and assess clinical outcomes. Clinical data from 16 patients with facial nerve spasms treated at the Department of Neurosurgery in the First Affiliated Hospital of Bengbu Medical College, between August 2020 and July 2023, were retrospectively examined. Preoperatively, all patients underwent magnetic resonance angiography to detect any offending blood vessels; ascertain the relationship between offending vessels, facial nerves, and the brainstem; and detect any cerebellopontine angle lesions. Surgery involved endoscopic MVD of the facial nerve using a mini Sigmoid sinus posterior approach. Various operative nuances were summarized and analyzed, and clinical efficacy, including postoperative complications and the extent of relief from facial paralysis, was evaluated. Fully endoscopic MVD was completed in all patients, with the offending vessels identified and adequately padded during surgery. The offending vessels were anterior inferior cerebellar artery in 12 cases (75%), vertebral artery in 3 cases (18.75%), and posterior inferior cerebellar artery in 1 case (6.25%). Intraoperative electrophysiological monitoring revealed that the lateral spread response of the facial nerve vanished in 15 cases and remained unchanged in 1 case. Postoperative facial spasms were promptly alleviated in 15 cases (93.75%) and delayed in 1 case (6.25%). Two cases of postoperative complications were recorded—one intracranial infection and one case of tinnitus—both were resolved or mitigated with treatment. All patients were subject to follow-up, with no instances of recurrence or mortality. Fully endoscopic MVD of the facial nerve is safe and effective. Proficiency in endoscopy and surgical skills are vital for performing this procedure.

Outcomes of Extended Middle Fossa Approach for Petroclival Tumors in the Elderly

Abstract Objective The aims of the study are (1) to evaluate the extended middle fossa approach (eMCF) for resection of tumors in the petroclivus and anterior cerebellopontine angle (CPA) and (2) to compare surgical outcomes between elderly (≥65 years) and nonelderly patients. Design Retrospective cohort. Setting Tertiary referral center. Participants Adults with petroclival, anterior CPA, or posterior fossa lesions who underwent an eMCF approach from 2012 to 2021 were included in the study. Main Outcome Measure Demographics, symptoms, cranial nerve (CN) function, and postoperative outcomes. Results Twenty-nine patients (mean age of 55 years, 59% females) were identified. Eleven (38%) were ≥65 years (65–79 years). The most common pathology was meningioma (n = 13, 45%), followed by vestibular schwannoma (n = 4, 14%) and squamous cell carcinoma (n = 3, 10%). Nineteen tumors (65.5%) were located in the petroclivus, 7 (24%) involved the cavernous sinus, and 10 (34%) were located in the posterior fossa. The mean tumor maximal diameter was 3.4 cm (range: 1.3–7.9 cm). Gross total tumor resection was accomplished in 15 (52%) patients. Most patients (n = 23, 79%) did not develop new CN deficits postoperatively. Of the 13 patients who had complete pre- and postoperative audiometric data, 69% (n = 9) maintained their hearing. Comparing the elderly versus nonelderly patients, there were no significant differences in the development of new CN palsies (p = 0.14), length of stay (p = 0.91), or incidence of postoperative complications (p = 0.30). Conclusions The eMCF approach provides exposure to the petroclival region, anterior CPA cistern, and posterior fossa for a variety of pathologies. It has a favorable safety profile in the elderly (≥65 years) population with low morbidity.

893 Posterior Location of the Facial Nerve in Vestibular Schwannoma: Report of a Rare Case and a Brief Literature Review

Abstract Background The commonest location of the facial nerve on the surface of a vestibular schwannoma (VS) is ventral. The posterior location of the facial nerve on the surface of a VS is extremely rare and is reported to be between 0.6-3.8%. In this illustrative case report, we present a case of a large VS with posterior location of the facial nerve on its surface. The surgical strategy in this situation to preserve the facial nerve both anatomically and physiologically is discussed. Ours is the first illustrative case of the posterior location of the seventh nerve on these tumours. Case Description An elderly man presented with right cerebellopontine (CP) angle syndrome. MRI showed a partly cystic and partly solid right CP angle lesion extending to the internal auditory meatus. Electrophysiological stimulation of the tumour showed that the facial nerve was located on the posterior surface of the tumour. Under the microscope, the facial nerve was identified on the posterior surface of the tumour. Partial excision of the tumour was done with preservation of the facial nerve both anatomically and physiologically. Conclusions This case reiterates the fact that even though rare, surgeons should anticipate the posterior location of the facial nerve on the surface of VS. Electrophysiological stimulation of the posterior surface of the tumour should be done before tumour resection in all cases to look for the posterior location of the facial nerve. Careful microsurgical dissection should be done to achieve maximal cytoreduction of the tumour, preserving the facial nerve.

Intraoperative Mapping of the Sensory Root of the Trigeminal Nerve in Patients with Pontocerebellar Angle Pathology

The aim of the present study was to determine the position of the 3 sensory branches of the trigeminal nerve in the preganglionic tract using intraoperative neurophysiological mapping. We included consecutive adult patients who underwent neurosurgical treatment of cerebellopontine angle lesions. The trigeminal nerve was antidromically stimulated at 3 sites along its circumference with different stimulus intensities at a distance of ≤1 cm from the brainstem. The sensory nerve action potentials (SNAPs) were recorded from each main trigeminal branch (V1 [ophthalmic branch], V2 [maxillary branch], and V3 [mandibular branch]). We analyzed 13 patients. The stimulation points at which we obtained the greatest number of congruous and exclusive SNAPs (SNAPs only on the stimulated branch) was the stimulation point for V3 (20.7%). The stimulation intensity at which we obtained the highest number of congruent and exclusive SNAPs with the stimulated branch was 0.5 mA. Using our recording conditions, trigeminal stimulation is a reliable technique for mapping the V3 and V1 branches using an intensity not exceeding 0.5. However, reliable identification of the fibers of V2 is more difficult. Stimulation of the trigeminal nerve can be a reliable technique to identify the V3 and V1 branches if rhizotomy of these branches is necessary.

Primary pilocytic astrocytoma of cerebello-pontine angle in the pediatric age group: literature review and case report

BackgroundPrimary pilocytic astrocytoma of the CPA (Cerebello-pontine angle), in the pediatric age group is an extremely rare entity, with just three cases reported so far. It mostly arises from the root entry zone of the cranial nerves found in this cistern.Case presentationA 11-year boy presented with headache, hearing impairment in right ear. Pure tone audiogram and BAER (Brainstem auditory evoked response) suggested retro-cochlear sensori-neural hearing loss. MRI revealed a heterogeneously enhancing extra-axial lesion in the right CPA. Tumor was approached through right retromastoid suboccipital craniotomy. Intraoperatively it seemed to arise from the REZ (root entry zone) of CN VIII and histopathology confirmed it to be pilocytic astrocytoma. We have reported this as only the fourth case and reviewed the already existing literature. In the previous case reports an extensive immunohistochemical analysis was not done and the final diagnosis was not as per the Harlem consensus guidelines.ConclusionIn this case, we have tried to report the final histopathology in accordance with the 5th edition of WHO classification of CNS tumors. In the current era of molecular diagnosis and layered structural format of reporting a histopathology, this case is the first of its kind and emphasizes the need to consider PA as one of the differentials for lesions in CPA.

Lymphoma of the cerebellopontine angle mimicking metastasis lesion: A case report

Primary lymphoma of the cerebellopontine angle (CPA) is rare and uncommon in the central nervous system, accounting for approximately 0.2-2% of all brain tumors. To our knowledge, there have only been 32 cases reported worldwide so far. Here, we report a rare case of B-cell lymphoma in a 56-year-old woman who presented with seizure, dysphagia, and dizziness and showed a lesion involving the left CPA, right frontal horn and septum pellucidum on magnetic resonance imaging (MRI). The primary diagnosis was metastatic tumor; however, Stereotactic biopsy on left CPA lesion was done, and the histological features confirmed the diagnosis of B-cell malignant lymphoma. The patient was treated with chemotherapy, with complete resolution of symptoms after the first chemotherapy session.

Suprafloccular transhorizontal fissure approach to the cerebellopontine angle: an anatomical study with case series.

The suprafloccular transhorizontal fissure approach is a modified variant of the classical retrosigmoid approach option to be chosen for cerebellopontine angle lesions. In this study, we aimed to demonstrate a previously described but not widely used method, the suprafloccular transhorizontal fissure approach with anatomical dissection on the cadaver, accompanied by a case presentation with the largest clinical series in the literature. Klingler's protocol was used to prepare 8 silicone injected and 8 non-silicone injected human hemispheres. A total of 210 patients who underwent surgery in the cerebellopontine angle between 2019 and 2022 were evaluated in our clinic. Of these, the suprafloccular transhorizontal fissure approach was applied in 33 patient, and it was successful in 26 patient, but this approach could not be achieved in 7 patients. The transhorizontal fissure is a fissure in the cerebellum located between the superior semilunar lobule and the inferior semilunar lobule. In the 26 patients we operated with the suprafloccular transhorizontal fissure approach, there was no need for retraction and no complications developed. However, in 7 patients, this fissure could not be dissected due to adhesions. Suprafloccular approach is an alternative to the classical retrosigmoid approach in tumours smaller than 2 cm, medially localised with little cerebellar oedema and neurovascular compression syndrome. Because in this approach, no cerebellum retraction is required, vascular structures are better preserved and the surgical time is shortened. This approach can be applied in smaller tumours than 2 cm when the sulcal anatomy is appropriate.

Case report: Efficacy of lutetium-177 oxodotreotide for neuroendocrine tumor with central nervous system metastases

Neuroendocrine tumors (NETs) rarely metastasize to the brain. However, when they occur, NET brain metastases are associated with a poor prognosis. Due to their low incidence, NET brain metastases are poorly studied, with few data to guide a consensus for management. Prior reports have documented treatment with chemotherapy, resection, whole brain radiation therapy, and stereotactic radiosurgery, all with low rates of survival. We present a case of a patient with type 3 well-differentiated gastric NET with widespread metastatic disease, including central nervous system lesions in the pineal gland and left cerebellopontine angle (CPA), which were avid on 68Ga-dotatate positron emission tomography. The patient received four doses of 200 mCi (7.4 GBq) lutetium-177 oxodotreotide (177Lu-dotatate) administered every 8 weeks over the course of 6 months. The treatments provided local control of the pineal and CPA lesions for 23 months until the development of diffuse leptomeningeal progression that necessitated further therapies. 177Lu-dotatate may be a viable treatment for local control of NET brain metastases. More studies are needed to validate its efficacy in this clinical scenario.

Labyrinthitis With Negative MRI As a Precursor to Rapidly Developing Primary CNS Lymphoma of the Cerebellopontine Angle.

Few case reports have described primary central nervous system lymphoma (PCNSL) presenting as a cerebellopontine angle (CPA) lesion in HIV-positive patients. We describe a rare presentation of rapidly progressing PCNSL of the CPA/internal auditory canal (IAC) as labyrinthitis with initial negative MRI in an HIV-positive patient. A 58-year-old male with well-controlled HIV presented with sudden left sensorineural hearing loss, tinnitus, and imbalance. Vestibular testing suggested an uncompensated left peripheral vestibular weakness. MRI demonstrated facial and cochleovestibular nerve enhancement within the CPA and IAC. The presumptive diagnosis of labyrinthitis was made. Two months later, he presented to his infectious disease provider with left facial weakness and disequilibrium and was treated for presumed Bell's palsy. One month later, he presented with left corneal reflex dysfunction, decreased visual acuity, diplopia, and worsening ataxia. Repeat MRI demonstrated a new 3.6 cm lesion of the left CPA/IAC with vasogenic edema. Despite location, the mass lacked the brainstem compression characteristic of other extra-axial CPA masses such as vestibular schwannoma. Flow cytometry and cytology from cerebrospinal fluid was consistent with primary central nervous system large B-cell lymphoma. We present a unique case of rapidly progressing PCNSL of the CPA/IAC in an HIV-positive patient, presenting initially as labyrinthitis with negative MRI followed by development of multiple cranial neuropathies and 3-month repeat MRI demonstrating a large CPA mass. In HIV-positive patients with a similar initial presentation, PCNSL should considered early in the diagnostic evaluation with close clinical monitoring and a low threshold for repeat imaging.

Post-operative Status of Facial Nerve in Cerebello-Pontine Angle Lesion via Retro-Sigmoid Approach; Complications and Outcome


 Objective: To assess the post-operative status of Facial Nerve in cerebellopontine angle (CPA) lesion via retro-sigmoid approach and also its complications and outcome.
 Materials & Methods: This prospective study was conducted at the Department of Neurosurgery, JPMC Karachi from a period of 10-12-2021 to 10-06-2022.The sample size of our study was 37 patients. All the patients were operated for CPA lesions and followed for three months to assess the outcome efficacy.
 Results: Our study showed that the mean age was 37 years, with a range of 27 to 65 years, in which the males were 18 (48.6%) and the females were 19 (51.4%). Out of 37 patients, 28 (75.7%) were diagnosed with vestibular schwannoma, while 6 (16.2%) were meningiomas, and 3 (8.1%) were epidermoid cysts. Gross total resection was performed in 14 (37.8%) patients, while subtotal resection (STR) in 23 (62.2%). Facial nerve function in terms of House-Brackmann at 3 months was found to be grade I in 26 (70.3%), grade II in 9 (24.3%), grade III in 1 (2.7%), and grade IV in 1 (2.7%).
 Conclusion: The CPA is a small corridor through which important neurovascular structures pass. Identification of CN VII is important in large CPA tumours to preserve facial motor nerve function. For all kinds of CPA lesions, gross total excision should be the aim of surgery.

Pilocytic astrocytoma of the cerebellopontine angle: a rare case

BackgroundPilocytic astrocytomas are the most common primary brain tumors in children. Most of the lesions occur in or near the midline. They are rare in extra-axial locations.Case presentationWe report a 23-year-old lady who was found to have progressive right-sided sensorineural hearing loss and features of raised intracranial pressure due to a pilocytic astrocytoma of the right cerebellopontine angle. After an extensive Medline search, we could find only three cases of primary extra-axial pilocytic astrocytoma of the cerebellopontine angle (CPA) reported till now.ConclusionEven a rare occurrence, primary pilocytic astrocytoma, and in general gliomas, should be kept in mind in the differential diagnosis of CPA lesions.

Application of Surface Landmarks Combined with Image-Guided Sinus Location in the Retrosigmoid Approach and Their Clinic-Image Relationship Analysis.

Objectives During craniotomy for cerebellopontine angle (CPA) lesions, the exact exposure of the margin of the venous sinuses complex remains an essential but risky part of the procedure. Here, we revealed the exact position of the asterion and sinus complex by combining preoperative image information and intraoperative cranial landmarks, and analyzed their clinic-image relationship. Methods Ninety-four patients who underwent removal of vestibular schwannoma (VS) through retrosigmoid craniotomies were enrolled in the series. To determine the exact location of the sigmoid sinus and the transverse sinus and sigmoid sinus junction (TSSJ), we used preoperative images, such as computed tomography (CT) and/or magnetic resonance imaging (MRI) combined with intraoperative anatomical landmarks. The distance between the asterion and the sigmoid sinus was measured using MRI T1 sequences with gadolinium and/or the CT bone window. Results In 94 cases of retrosigmoid craniotomies, the asterion lay an average of 12.71 mm on the posterior to the body surface projection to the TSSJ. Intraoperative cranial surface landmarks were used in combination with preoperative image information to identify the distance from the asterion to the sigmoid sinus at the transverse sinus level, allowing for an appropriate initial burr hole (the margin of the TSSJ). Conclusion By combining intraoperative anatomical landmarks and preoperative image information, the margin of the TSSJ, in particular, the inferior margin of the transverse sinus, can be well and thoroughly identified in the retrosigmoid approach.

Case Report: Extensive Temporal Bone Invasion in a Giant Vestibular Schwannoma

BackgroundRare giant vestibular schwannomas (GVSs) invade the temporal bone extensively, which carries unique risks for surgery owing to their complicated relationship with adjacent structures, difficult dissection of the temporal bone, and high risk of complications. The underlying mechanism of this invasive behavior remains unknown.Case descriptionWe report on a 28-year-old woman who presented with typical hearing loss and facial paralysis (House-Brackmann II). Magnetic resonance imaging exhibited a giant mass (∼5.0 cm) in the right cerebellopontine angle (CPA), petrous apex, and middle cranial fossa. Her primary diagnosis was GVS with petrous apex invasion. With the aid of presurgical imaging reconstruction and intraoperative facial nerve monitoring, we adopted a sequential therapeutic strategy, which included microsurgery for the CPA lesion followed by gamma knife radiosurgery (GKRS) for the petrous mass. During follow-up, stable tumor control was achieved with functional preservation of the facial nerve and no other complications. The postoperative immunohistochemical examination demonstrated dramatic intratumoral inflammation, which suggested its potential role in bony erosion. We reviewed the literature of large vestibular schwannoma with a petrous invasion and further discussed its treatment.ConclusionMicrosurgery remains the top therapeutic strategy for GVS. However, gross total resection with functional preservation of cranial nerves is challenging to achieve once the temporal bone is involved. In this case, we applied a planned and sequential approach of microsurgery and GKRS with a promising outcome, which highlighted this combinational strategy in this rare situation. In addition, pathological examination suggested that intratumoral inflammation might play a role in the bony erosion of GVS. Longer observation and more cases are needed to further investigate its molecular mechanism and treatment plan.

Hemorrhagic vestibular schwannoma: a case example of vestibular apoplexy syndrome. Illustrative case.

BACKGROUNDAcute intratumoral hemorrhage within a vestibular schwannoma, or vestibular apoplexy, is a rare condition. Unlike the typical insidious vestibulopathy typically caused by vestibular schwannoma growth, patients with vestibular apoplexy have an acute and severe presentation with nausea and emesis in addition to severe vertigo and hearing loss. Here, the authors present an illustrative case demonstrating this rare clinical condition and an operative video detailing the surgical management.OBSERVATIONSA 76-year-old man presented to the emergency department with acute-onset dizziness, left-ear fullness, double vision, gait ataxia, emesis, and facial numbness. Imaging revealed a 2.8-cm hemorrhagic left cerebellopontine angle lesion extending into the left internal auditory canal, consistent with hemorrhagic vestibular schwannoma. The patient subsequently underwent a retrosigmoid craniotomy for resection of the hemorrhagic mass, and by 1 month after surgery, all his presenting symptoms had resolved, allowing his return to daily activities.LESSONSVestibular schwannomas typically present with decreased hearing and chronic vestibulopathy. Acute presentation should raise the suspicion for an apoplectic event, and surgical debulking may lead to improvement in most vestibular symptoms.

Microsurgical Resection of Cerebellopontine Angle Medulloblastoma, Case Report and Review of Literature

Cerebellopontine angle (CPA) medulloblastomas (MB) are rare lesions with few cases previously described in the literature. We report one more case of CPA MB. The patient was a (36)-year-old female with a mass developing in the CPA. The preoperative radiological diagnosis was (hemangioblastoma) in the case. The patient was operated in Tripoli university hospital September 2020 neurosurgical department. Operated through a (retrosigmoid) approach. The intraoperative findings revealed an extra-axial tumor and the histological diagnosis was classic type of MB in the case. We review the literature and discuss pathological, radiological features and clinical follow up of CPA MB, underlining the necessity to consider MB in the differential diagnosis of CPA lesions.

The Strategy of Facial Nerve Preservation in Acoustic Neuroma Surgery via Suboccipital Retrosigmoid Approach

Acoustic neuroma is a common intracranial tumor, with a prevalence of 80~90% in the lesions of cerebellopontine angle. Microsurgical removal remains its main therapy, and the retrosigmoid approach continues to be the most widely employed strategy for the surgical resection of acoustic neuromas, with preservation of facial nerve to be the important goal. In order to preserve the facial nerve, the facial nerve's function should be evaluated accurately before and after the operation. The course of the facial nerve and its variation in cerebellopontine cistern and internal auditory canal should be well understood. Adequate drilling of the posterior wall of the internal auditory canal is necessary. Sufficient decompression of intracranial pressure and the tumor is imperative. The principle of subperineural and bidirectionary dissection should be followed. The use of bipolar coagulation should decrease to the greatest extent, and facial nerve monitoring should be used throughout exposing and removal of the acoustic neuroma.

Clinical comparison of single-shot EPI, readout-segmented EPI and TGSE-BLADE for diffusion-weighted imaging of cerebellopontine angle tumors on 3 tesla

ObjectiveThe complex anatomical structures of cerebellopontine angle (CPA) pose a unique challenge to diffusion weighted imaging (DWI). This study aimed to compare the clinical utility of the prototypic 2D turbo gradient- and spin echo-BLADE-DWI (TGSE-BLADE-DWI) with that of readout-segmented echo-planar DWI (RESOLVE-DWI) and single-shot echo-planar DWI (SS-EPI-DWI) to visualize CPA anatomic structures and identify CPA tumors. MethodsA total of 8 volunteers and 36 patients with pathological CPA tumors were enrolled to perform the three DWI sequences at 3 T. Scan time of TGSE-BLADE-DWI, RESOLVE-DWI and SS-EPI-DWI was 5 min 51 s, 5 min 15 s and 1 min 22 s, respectively. Subjective analysis, including visualization of anatomical structures, geometric distortion, ghosting artifacts, lesion conspicuity, diagnostic confidence, and overall image quality of the three DWI sequences were scored and assessed. Signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and apparent diffusion coefficient (ADC) of CPA tumors were measured and compared. ResultsA total of 39 lesions were identified, TGSE-BLADE-DWI detected all of them, RESOLVE-DWI 36 and SS-EPI-DWI 27. Significant differences were found in all the subjective parameters among the three DWI sequences (all p < 0.001). TGSE-BLADE-DWI was significantly better than RESOLVE-DWI in visualization of CPA anatomical structures, geometric distortion, ghosting artifacts, lesion conspicuity, diagnostic confidence, and overall image quality (all p < 0.01), and RESOLVE-DWI showed significantly superior performance than SS-EPI-DWI in all parameters (all p < 0.001). CNRs and ADCs were not significantly different among the three DWI sequences (p = 0.355, p = 0.590, respectively). No significant differences were detected between TGSE-BLADE-DWI SNR and RESOLVE-DWI SNR (p = 0.058), or TGSE-BLADE-DWI SNR and SS-EPI-DWI SNR (p = 0.155). ConclusionCompared with RESOLVE-DWI and SS-EPI-DWI, TGSE-BLADE-DWI minimized geometric distortions and ghosting artifacts and demonstrated an improved ability for depicting CPA tumors with better lesion conspicuity. SummaryGeometric distortions and ghosting artifacts are found at bone-air interfaces using conventional diffusion-weighted imaging (DWI), which is a challenge for imaging cerebellopontine angle (CPA) tumors. Our study validated that geometric distortions and ghosting artifacts were not present on 2D turbo gradient- and spin-echo-BLADE-DWI scans, making this technique useful for visualizing CPA anatomic structures and diagnosing CPA tumors.

Schwannoma of the Intermediate Nerve: A Rare Type of Cerebellopontine Angle Tumor

Abstract&#x0D; Background: Schwannoma of the Intermediate Nerve is rare. The most majority of Cerebellopontine angle (CPA) lesions are Vestibular Schwannomas.&#x0D; Case description: A 50-year-old woman presented with ear pain, facial palsy and hypoacusis. MRI revealed a CPA tumor. A left retrosigmoid approach and microsurgery was performed and the tumor origin was from the intermediate nerve. intraoperative neurophysiologic monitoring (MNIO) was used during the surgery. Conclusion: Schwannomas of the intermediate nerve is indistinguishable from vestibular schwannomas on preoperatory image, however it’s possible to identify tumor origin during microsurgery dissection with aid of MNIO and origin from intermediate nerve is a reality.