Secondary trigeminal neuralgia in cerebellopontine angle tumors

Efficacy and safety of Dyna CT-assisted percutaneous balloon compression in the treatment of tumor-related trigeminal neuralgia: A single-center retrospective analysis

BACKGROUND

Percutaneous balloon compression (PBC) has been widely used in the treatment of trigeminal neuralgia (TN). Patients with tumor-related TN are typically treated by tumor resection. However, when craniotomy is not feasible, PBC may serve as a simple and effective method for pain relief. Currently, there is limited literature on the use of this technique in treating patients with tumor-related TN. In this study, we aim to evaluate the efficacy and safety of Dyna CT-assisted PBC in the treatment of tumor-related TN.

METHODS

From January 2018 to December 2023, a total of 19 patients with tumor-related TN underwent Dyna CT-assisted PBC at our institution. The modified Barrow Neurological Institute Pain Intensity Grading Scale and sensory reduction scores were employed to assess treatment outcomes. A retrospective analysis was conducted on the clinical characteristics, surgical efficacy, postoperative complications, and follow-up results of all patients.

RESULTS

Immediate and complete pain relief was observed in 18 patients following PBC, with one patient experiencing delayed recovery. Follow-up periods ranged from 4 to 62 months, revealing only 4 patients with pain recurrence at the last follow-up, and tumor-related TN patients with involvement of Meckel's cave were more prone to recurrence. No severe complications occurred throughout the follow-up period. Although facial numbness was reported in all 15 patients, jaw weakness in 8 patients, and postoperative headache in 7 patients, these symptoms resolved within a short period. There were no statistically significant differences in postoperative facial numbness and jaw weakness between tumor-related TN patients with or without Meckel's cave involvement. However, patients with Meckel's cave involvement were more likely to experience postoperative headaches. Patient satisfaction scores indicated a significant improvement in postoperative quality of life.

CONCLUSION

For patients with tumor-related TN, when craniotomy is not feasible, Dyna CT-assisted PBC proves to be a safe and effective alternative treatment. Additionally, we observed varying postoperative clinical outcomes based on the different sites of tumor compression on the trigeminal nerve. Patients with tumor-related TN not involving Meckel's cave exhibited more enduring clinical efficacy compared to those with Meckel's cave involvement.

Outcomes of Trigeminal Ganglion Sparing Surgical Resection of Nonacoustic Cerebellopontine Angle Tumors Causing Trigeminal Neuralgia

OBJECTIVE

Tumors may be responsible for up to 5% of trigeminal neuralgia cases. Predictors of long-term pain relief after surgical resection of various cerebellopontine angle tumor types are not well understood. Previous studies found that size and extent of resection predict long-term pain status, although resection of tumor involving the trigeminal ganglion may be associated with high morbidity. This study evaluated predictors of TN pain freedom after resection of a nonacoustic CPA tumor, with avoidance of any portion involving the TG.

METHODS

In a retrospective cohort study, we evaluated clinical outcomes and complications after surgical resection of nonacoustic CPA tumors with purposeful avoidance of the TG causing trigeminal neuralgia. The primary outcome was pain-freedom. We performed logistic regression analyses to examine the relationship between pain-freedom at last follow-up and age, side of symptoms, preoperative symptom duration, tumor diameter, tumor type, and concurrent neurovascular compression (NVC).

RESULTS

Of 18 patients with nonacoustic CPA tumors causing TN treated with surgical resection, 83.3% were pain-free at last follow-up (mean 44.6 months). Age (P = 0.12), side (P = 0.41), preoperative symptom duration (P = 0.85), tumor diameter (P = 0.29), tumor type (P = 0.37), and NVC presence (P = 0.075) were not associated with long-term pain freedom.

CONCLUSIONS

This study provides additional evidence that various tumor types causing TN may safely undergo surgical resection and decompression of the trigeminal nerve to treat TN. This study presents a cohort of patients that underwent resection of a nonacoustic CPA tumor, with purposeful avoidance of the TG to minimize complications, demonstrating high rates of long-term pain freedom.

An Atypical Presentation of Acoustic Neuroma With Facial Paresthesia: A Case Report

Acoustic neuromas are benign neoplasms of the brain composed of Schwann cells, arising most commonly from the nerve sheath of the vestibular division of the VIII cranial nerve. They usually manifest as unilateral hearing loss, tinnitus, and unsteadiness. Some patients may present atypically with symptoms like orofacial pain, hemifacial numbness, sudden onset hearing loss, or trigeminal neuralgia. Here we report an interesting case of acoustic neuroma in which the patient presented with unilateral facial numbness and tooth pain. Persistent atypical symptoms should always raise clinical suspicion of this pathology, necessitating the need for higher radiological investigations (CT or MRI) to aid in the early diagnosis and treatment.

Trigeminal neuralgia secondary to epidermoid cyst and neurovascular conflict: An illustrative case with literature review

Background

Trigeminal neuralgia (TN) is a highly disabling facial pain syndrome, historically known as the suicide disease, in which most cases can be cured with appropriate surgical treatment.

Case Description

We present the case of a 43-year-old male farmer with acute, self-limiting episodes of shock-like pain on the left side of the face that started in June of 2021. He was diagnosed with TN and was treated with carbamazepine. Magnetic resonance imaging was performed, which revealed an epidermoid cyst (EC) at the prepontine cistern with an extension to the left cerebellopontine angle. The neurosurgery department at our institution was consulted, which performed surgical tumor resection and Vth cranial nerve decompression. During the resection, a neurovascular conflict (NVC) was identified at the root entry zone. After the resection around the nerve and its whole tract was completed, a microvascular decompression (MVD) was performed.

Conclusion

TN secondary to EC in association with a NVC is a rare phenomenon, due to the growth pattern of the EC. TN may remit if an appropriate treatment is carried out. In cases of NVC, an MVD is required apart from an appropriate resection to achieve pain relief.

[Posterior petrous meningioma with secondary trigeminal neuralgia: microsurgical resection after stereotactic radiosurgery (case report and literature review)]

According to the literature, cerebellopontine angle tumors cause secondary trigeminal neuralgia and other symptoms of neurovascular compression in 1-9.9% of cases. We present a 58-year-old patient with left-sided secondary trigeminal neuralgia caused by ipsilateral posterior petrous meningioma. Stereotactic irradiation was followed by effective tumor growth control. However, residual trigeminal pain paroxysms significantly reduced the quality of life and required subsequent microsurgery. Trigeminal facial pain regressed after total resection of tumor. Considering this clinical case, we would like to discuss several issues: follow-up of meningioma requiring radiosurgery, course of secondary trigeminal neuralgia in a patient with apical petrous meningioma, characteristics of pain before and after radiosurgery, the best treatment option for these patients. Stereotactic radiosurgery seems unreasonable for CPA tumors with secondary trigeminal neuralgia. Indeed, persistent pain is possible even after tumor shrinkage. Moreover, primary stereotactic irradiation significantly complicates subsequent resection of tumor.

Comparison of the efficacy in improving trigeminal neuralgia in petroclival meningioma between microsurgery and radiosurgery: a meta-analysis

The purpose of this study was to systematically review studies in the literature to assess the superiority between microsurgery and radiosurgery regarding the efficacy in improving petroclival meningioma (PCM)-related trigeminal neuralgia (TN). PubMed, Embase, Web of Science, and Cochrane clinical trial databases were systematically searched from the inception until December 08, 2022. The overall proportion of patients with improved TN after treatment in all six included studies was 56% (95% confidence interval [CI], 35-76.9%). Higgins I2 statistics showed significant heterogeneity (I2 = 90%). Subgroup analysis showed that the proportion of improved TN was higher in the microsurgery group than that in the radiosurgery group (89%; 95% CI, 81-96.5% vs. 37%, 95% CI, 22-52.7%, respectively, p < 0.01). Subgroup analysis (for studies that documented the number of posttreatment Barrow Neurological Institute scores 1 and 2) revealed that the proportion of pain-free without medication after treatment was higher in the microsurgery group than that in the radiosurgery group (90.7%; 95% CI, 81-99.7% vs. 34.5%, 95% CI, 21.3-47.7.7%, respectively, p < 0.01). Based on the results of this meta-analysis, we concluded that microsurgery is superior to radiosurgery in controlling PCM-related TN.

Balloon compression, neuroendoscopy and electrophysiological monitoring-assisted retrosigmoid approach for resection of cholesteatoma in the cerebellopontine angle-Meckel's cave: a technical description

We report a case of cholesteatoma that caused left facial pain with facial numbness. The tumour was located in the left cerebellopontine angle (CPA) and Meckel's cave. A balloon was first placed into Meckel's cave, and then, under electrophysiological monitoring, the tumour within the CPA cistern was resected via the retrosigmoid approach. The balloon was inflated in Meckel's cave to push the tumour out of Meckel's cave, and then, the tumour was completely removed under endoscopy. The symptoms, including pain and numbness, subsided after surgery.

Open surgery vs. stereotactic radiosurgery for tumour-related trigeminal neuralgia: A systematic review

BACKGROUND

Secondary trigeminal neuralgia is a facial pain in trigeminal nerve dermatome caused by an underlying disease, such as cerebellopontine angle tumours. Treatment options to relieve the pains were surgical tumour resection and stereotactic radiosurgery of the tumour or trigeminal nerve. This study aims to review the efficacy of open surgery and stereotactic radiosurgery and recommend the treatment of choice for secondary trigeminal neuralgia due to cerebellopontine angle tumours.

METHOD

The inclusion criteria were studies covering patients with trigeminal neuralgia associated with cerebellopontine angle tumours that were treated with either open surgery or stereotactic radiosurgery and reported pain outcomes after treatment. Non-English articles or studies with a population of less than five were excluded. We systematically searched studies from PubMed, Ebscohost, and Cochrane Library from inception until December 20, 2021. Several works of literature from manual search were also added. Selected articles were appraised using a critical appraisal tool for prognostic studies.

RESULT

Included articles were 26 retrospective studies and one prospective study comprising 517 patients. Of 127 schwannomas, 226 epidermoids, 154 meningiomas, and ten other tumours, 320 cases received surgical tumour excision with or without MVD, 196 had tumour-targeted radiosurgery, and 22 underwent nerve-targeted radiosurgery. In surgical series, 92.2 % gained pain improvement, 2.8 % were unchanged, and 4.5 % had recurrence; none of the patients had worsened outcomes. In cases treated with tumour-targeted radiosurgery, the improvement rate was 79.1 %, unchanged at 14.3 %, recurrence at 26.5 %, and worse symptoms rate after the intervention was 6.6 %. Six patients with recurrent pain after tumour-targeted radiosurgery received secondary nerve-targeted radiosurgery with improved outcomes. Only one patient in our review underwent primary nerve-targeted radiosurgery, and the result was satisfactory. One study treated 15 patients with a single session of tumour-targeted and nerve-targeted radiosurgery, with an improvement rate of 93.3 % and a recurrence rate of 21.4 %.

CONCLUSION

Open surgery releasing the nerve root from compressive lesions is advocated to be the first-line treatment to gain satisfactory outcomes. Total removal surgery is recommended if possible. Nerve-targeted radiosurgery should be reserved as a secondary treatment for recurrent cases.

Trigeminal neuralgia in patients with cerebellopontine angle tumors: should we always blame the tumor? A case report and review of literature

OBJECTIVES

This report seeks to highlight a pitfall that may be encountered in the management of patients with trigeminal neuralgia with imaging showing both neurovascular conflict as well as tumors.

CASE PRESENTATION

A case of a 53 year old male with simultaneous neurovascular conflict and a vestibular schwannoma with trigeminal neuralgia is presented and the management is discussed with reference to managing this particular subset. Pain was noted to be likely generated by neurovascular conflict and not by the tumor, which is usually not the case.

CONCLUSIONS

It is suggested that in such cases, microvascular decompression should always be performed in addition to removal of the tumor.

Percutaneous balloon compression for secondary trigeminal neuralgia caused by cerebellopontine angle tumors

OBJECTIVE

The most common cause for trigeminal neuralgia (TN) is vascular compression at the nerve root, and microvascular decompression (MVD) has been proven to be an effective surgical approach for this disease. For some patients, TN is secondary to the intracranial space-occupying lesion, and tumor resection is usually recommended. However, it is not easy to determine proper treatments when craniotomy is infeasible. In this study, we aim to explore the clinical outcomes of percutaneous balloon compression (PBC) for secondary TN caused by cerebellopontine angle (CPA) tumors.

METHODS

From June 2016 to December 2019, 15 patients with TN caused by CPA tumors underwent PBC in Nanjing Drum Tower Hospital. The clinical features, surgical outcomes, and complications of these patients were analyzed retrospectively.

RESULTS

Fourteen out of the 15 patients had immediate pain relief after successful PBC, while one showed occasional pain, without needing any medication. No patients had a relapse of facial pain within a mean follow-up of 32.5 months. As for surgical complications, 14 patients experienced facial numbness, and six had masseter muscle weakness. No patients experienced serious surgical morbidities.

CONCLUSIONS

For the patients with TN caused by CPA tumors, PBC could be considered a useful technique, especially when craniotomy is infeasible.

Stereotactic radiosurgery for trigeminal neuralgia secondary to tumor: a single-institution retrospective series

OBJECTIVE

Trigeminal neuralgia (TN) secondary to tumor represents a rare and diverse entity, and treatment for secondary TN remains controversial. This report reviews a single institution’s experience in treating secondary TN with stereotactic radiosurgery (SRS) and focuses on the durability of pain relief with respect to various treatment targets, i.e., the trigeminal nerve, offending tumor, or both.

METHODS

Between the years 2009 and 2021, 21 patients with TN secondary to benign (n = 13) or malignant (n = 8) tumors underwent SRS. Barrow Neurological Institute (BNI) pain intensity scale scores were collected from patient electronic medical records at baseline, initial follow-up, and 1 and 3 years post-SRS. The interval change in BNI scale score (ΔBNI) at the various follow-up time points was also calculated to assess the durability of pain relief following SRS.

RESULTS

The median follow-up period was 24 (range 0.5–155) months. Five patients (24%) received treatment to the trigeminal nerve only, 10 (48%) received treatment to the tumor only, and 6 (29%) had treatment to both the nerve and tumor. The overall radiation dosage ranged from 14 to 60 Gy delivered in 1–5 fractions, with a median overall dose of 26 Gy. The median dose to the tumor was 22.5 (range 14–35) Gy, delivered in 1–5 fractions. Of the treatments targeting the tumor, 25% were delivered in a single fraction with doses ranging from 14 to 20 Gy, 60% were delivered in 3 fractions with doses ranging from 18 to 27 Gy, and 15% were delivered in 5 fractions with doses ranging from 25 to 35 Gy. The most common dose regimen for tumor treatment was 24 Gy in 3 fractions. The median biologically effective dose (with an assumed alpha/beta ratio of 10 [BED10]) for tumor treatments was 43.1 (range 13.3–60.0) Gy. There was a significant difference in the proportion of patients with recurrent pain (ΔBNI score ≥ 0) at the time of last follow-up across the differing SRS treatment targets: trigeminal nerve only, tumor only, or both (p = 0.04). At the time of last follow-up, the median ΔBNI score after SRS to the nerve only was −1, 0 after SRS to tumor only, and −2 after SRS to both targets.

CONCLUSIONS

SRS offers clinical symptomatic benefit to patients with TN secondary to tumor. For optimal pain relief and response durability, treatment targeting both the tumor and the trigeminal nerve appears to be most advantageous.

Drilling off the Petrosal Apex and Opening the Upper Wall of Meckel's Cave Are the Key Elements of Good Outcomes in the Treatment of Trigeminal Neuralgia Secondary to Petrous Apex Meningioma

Objective

The surgical management of trigeminal neuralgia (TN) caused by petrous apex meningioma (PAM) is still a challenge because of the lesion’s deep location and the surrounding complex structures. The authors describe the intradural anterior transpetrosal approach (ATPA) and its effect on the treatment of TN secondary to PAM.

Methods

A retrospective analysis of 15 patients with TN secondary to PAM who underwent surgery via the intradural ATPA was conducted. The key techniques, which included drilling off the petrosal apex (PA) and opening the upper wall of Meckel’s cave (MC), are described in detail.

Results

Total removal of the tumor and complete pain relief (Barrow Neurological Institute I) were achieved in all 15 patients without significant morbidity. Five patients developed new facial numbness postoperatively, which disappeared within three months after surgery. The postoperative magnetic resonance imaging showed temporal lobe swelling in three patients, but no clinical symptoms. One patient had cerebrospinal fluid leakage and was managed with bed rest and temporary lumbar drainage. One patient had an intracranial infection and was treated with antibiotics. By the last follow up, no patients had pain relapse or/and tumor recurrence. It is worth noting that the vascular compression at the root of the trigeminal nerve was found in one patient during the operation.

Conclusion

Our experience suggests that drilling off the PA and opening the upper wall of the MC are key elements for a good outcome of the treatment of TN secondary to PAM. The intradural ATPA has the advantages for both tumor resection and pain relief.

Diagnostic Value of Preoperative Electrodiagnostic Analysis in a Patient with Facial Palsy and a Large Vestibular Schwannoma: Case Report

Although radiologic methods confirm the diagnosis of patients with large vestibular schwannomas, these methods usually indicate only the size of the tumor and its possible nerve compression. Electrodiagnostic methods can reveal the functional state of the nerves, particularly the trigeminal and facial nerves, as well as providing a basis for objectively evaluating nerve injury. Due to the lack of an established objective evaluation method, electrodiagnostic methods were utilized to assess injury to the cranial nerve in a patient with a large vestibular schwannoma. A 79-year-old woman presented with a one-month history of right facial palsy, vertigo, dizziness, right postauricular pain, and right-sided hearing disturbance. Physical examination suggested injuries to the facial and vestibulocochlear nerves. Magnetic resonance imaging identified a vestibular schwannoma and showed that the tumor mass was affecting the brainstem, including the fourth ventricle, resulting in mild obstructive hydrocephalus. Preoperative electrodiagnostic evaluation identified asymptomatic trigeminal neuropathy accompanying a vestibular schwannoma. The patient underwent surgery, consisting of a suboccipital craniotomy with additional gamma knife radiosurgery. Postoperatively, she demonstrated significant recovery from right facial palsy and partial improvement of her neurologic symptoms. Large vestibular schwannomas with facial paralysis may be accompanied by additional entrapment neuropathy. Routine preoperative electrophysiological evaluation is recommended to establish a definitive diagnosis and evaluate the function of the trigeminal nerve, facial nerve, and brainstem in patients with large and compressive vestibular schwannomas.

Facial pain and sensory outcomes following resection of tumors compressing the trigeminal nerve

OBJECTIVE

Tumors compressing the trigeminal nerve can cause facial pain, numbness, or paresthesias. Limited data exist describing how these symptoms change after resection and what factors predict symptom improvement. The objective of this study was to report trigeminal pain and sensory outcomes after tumor resection and identify factors predicting postoperative symptom improvement.

METHODS

This retrospective study included patients with tumors causing facial pain, numbness, or paresthesias who underwent resection. Trigeminal schwannomas were excluded. Logistic regression, recursive partitioning, and time-to-event analyses were used to report outcomes and identify variables associated with facial sensory outcomes.

RESULTS

Eighty-six patients met inclusion criteria, and the median follow-up was 3.1 years; 63 patients (73%) had meningiomas and 23 (27%) had vestibular schwannomas (VSs). Meningioma patients presented with pain, numbness, and paresthesias in 56%, 76%, and 25% of cases, respectively, compared with 9%, 91%, and 39%, respectively, for patients with VS. Most meningioma patients had symptoms for less than 1 year (60%), whereas the majority of VS patients had symptoms for 1-5 years (59%). The median meningioma and VS diameters were 3.0 and 3.4 cm, respectively. For patients with meningiomas, gross-total resection (GTR) was achieved in 27% of patients, near-total resection (NTR) in 29%, and subtotal resection (STR) in 44%. For patients with VS, GTR was achieved in 9%, NTR in 30%, and STR in 61%. Pain improved immediately after tumor resection in 81% of patients and in 92% of patients by 6 weeks. Paresthesias improved immediately in 80% of patients, increasing to 84% by 6 weeks. Numbness improved more slowly, with 52% of patients improving immediately, increasing to 79% by 2 years. Pain recurred in 22% of patients with meningiomas and 0% of patients with VSs. After resection, the Barrow Neurological Institute (BNI) facial pain intensity score improved in 73% of patients. The tumor diameter significantly predicted improvement in BNI score (OR 0.47/cm larger, 95% CI 0.22-0.99; p = 0.047). Complete decompression of the trigeminal nerve was associated with qualitative improvement in pain (p = 0.037) and decreased pain recurrence (OR 0.08, 95% CI 0.01-0.67; p = 0.024).

CONCLUSIONS

Most patients with facial sensory symptoms caused by meningiomas or VSs experienced improvement after resection. Surgery led to immediate and sustained improvement in pain and paresthesias, whereas numbness was slower to improve. Patients with smaller tumors and complete decompression of the trigeminal nerve were more likely to experience improvement in facial pain.

Facial pain and trigeminal neuralgia secondary to metastasis: A case report

BACKGROUND AND OVERVIEW

Trigeminal neuralgia due to a metastatic lesion is a relatively rare occurrence. These cases pose a diagnostic challenge for the clinician due to a complex clinical presentation.

CASE DESCRIPTION

The authors describe the case of a 65-year-old woman with left-sided facial pain and occasional numbness. The patient also reported autonomic features associated with facial pain, facial muscular weakness, and hearing and visual impairment. The patient's history of breast cancer, for which she was receiving treatment for bone metastasis, warranted diagnostic imaging. Magnetic resonance imaging with and without contrast was performed and revealed a possible metastatic lesion.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Unusual clinical features must be identified, and prompt appropriate imaging is instrumental in making at an accurate diagnosis and management plan.

Invisible compression, anterior fossa tumor causing trigeminal neuralgia

Background:

Trigeminal neuralgia secondary to posterior and middle fossae tumors, whether ipsilateral or contralateral, has been well described. However, this disabling disease has never been reported in the context of anterior fossa neoplasms.

Case Description:

A 75-year-old female with right hemifacial pain was diagnosed with an anterior clinoid meningioma. Despite neuroimaging did not show any apparent anatomical or neurovascular conflict, a detailed MRI analysis revealed a V3 hyperintensity. Not only symptoms completely resolved after surgical resection but also this radiological sign disappeared. Nowadays, the patient remains asymptomatic and V3 hyperintensity has not reappeared during her follow-up.

Conclusion:

A surgical definitive treatment can be offered to patients suffering from trigeminal neuralgia secondary to lesions adjacent to Gasserian ganglion or trigeminal branches. In this respect, posterior and middle fossae tumors are well-reported etiologies. Nevertheless, in the absence of evident compression, other neoplasms located in the vicinity of these critical structures and considered as radiological findings may be involved in trigeminal pain. Microvascular and pressure gradient changes could be an underlying cause of these symptoms in anterior skull base lesions. Here, we report the case of a patient with uncontrollable hemifacial pain resolved after anterior clinoid meningioma removal.

Trigeminal Neuralgia Secondary to Intracranial Neoplastic Lesions: a Case Series and Comprehensive Review

It is known that intracranial tumors may trigger trigeminal neuralgia (TN) in some patients although the exact prevalence and occurrence is not completely defined yet. In the present study, we present a case series of patients with brain tumor and a clinical diagnosis of TN as the first and main manifestation of the disease. A retrospective analysis was performed involving patients diagnosed with brain tumor whose exclusive clinical feature our department focused on was TN. In addition, a review of all published cases was performed. From January 2017 to November 2018, 718 patients with brain tumor were admitted to our department, 17 of which suffered of TN, of which 8 patients presented with at least another neurologic symptom and 9 patients presented with TN alone, with typical symptoms of stubbing electric pain in 6 cases. In our series, we found that 2.3% of patients admitted for brain tumors had TN. In 0.8% of cases, TN was the main clinical symptom. The prevalence of tumor lesion in patients with facial neuropathic pain is not defined, but it is a well-known recognized initial symptom; however, early cerebral magnetic resonance imaging (MRI) is not yet strongly recommended in patients with newly diagnosed trigeminal neuralgia. The purpose of this article is, especially in unusual cases, to show that the application of such MR techniques and preoperative evaluation may contribute to diagnosis, indication, and surgery planning.

Radiosurgery vs. microsurgery for newly diagnosed, small petroclival meningiomas with trigeminal neuralgia

Trigeminal neuralgia (TN) is an excruciating pain that can occur with petroclival meningiomas (PCMs). Gamma knife radiosurgery (GKRS) is an appealing option for small PCMs, but the role of microsurgery (MS) compared to GKRS is not well defined for small PCMs with regard to TN relief. From January 2009 to September 2019, 70 consecutive patients were treated by GKRS or MS for newly diagnosed, small (< 3.5 cm) PCMs with TN. GKRS or MS were performed for 35 patients each. The surgical outcome and TN control according to Barrow Neurological Institute (BNI) score were retrospectively analyzed and compared between GKRS and MS. The predominant origin of PCMs was upper clival (49%) with trigeminal nerve compression at the medial dorsal root entry zone. Tumor control rates were equally 94% with GKRS or MS for a mean tumor size and volume of 2.3 cm and 5.3 cm³, respectively. The preoperative BNI scores were mostly II (40%) and IV (37%) with GKRS and MS, respectively. TN relief without medications (BNI scores I and II) was achieved in 13 of 35 patients (37%) with GKRS and 32 of 35 patients (91%) with MS during a mean follow-up of 50.5 months. The most common complications after GKRS and MS were dysesthesia (23%) and diplopia (9%), respectively. MS could be more effective than GKRS in providing prompt, medication-free pain relief from TN for small PCMs. The risks of MS have to be considered carefully in experienced hands, especially for small PCMs.

Surgical Treatment of Secondary Trigeminal Neuralgia Induced by Cerebellopontine Angle Tumors: A Single-Center Experience

OBJECTIVE

Secondary trigeminal neuralgia (TN) caused by cerebellopontine angle (CPA) tumors are rare, although TN may be a primary manifestation in the neurosurgery department. In this study, we aimed to retrospectively assess patients with CPA tumor-induced TN from a single center.

METHODS

Of 819 consecutive patients with TN treated at our center between 2007 and 2017, 36 with CPA tumor-induced TN were enrolled, and their medical and surgical records were analyzed.

RESULTS

The 36 patients accounted for 4.4% of all patients with TN. A comparison of patients with classic and tumor-induced TN indicated significant intergroup differences in the mean age at surgery (58.94 vs. 49.33 years, P = 0.000), the mean age at onset of TN (52.01 vs. 38.04 years), and affected side (298/485 vs. 22/14 in left/right, P = 0.006); no such difference was noted in the sex ratio (0.598 vs. 0.385, P = 0.214). The rates of excellent, good, and fair clinical outcomes were 80.56%, 13.89%, and 2.78%, respectively. The offending vessels found during surgery included the superior and anterior inferior cerebellar arteries in 3 and 4 cases, respectively. Postoperative complications included aseptic meningitis (1 case), facial numbness (2 cases), hearing disturbance (3 cases), facial palsy (4 cases), hemorrhage (1 case), and diplopia (2 cases).

CONCLUSIONS

Secondary TN caused by CPA tumors is not as frequent as classic TN. Compared with classic TN, tumor-induced TN is characterized by symptom onset and surgery at a younger age. Direct compression rather than chemical irritation is the cause of secondary TN.

Trigeminal neuralgia secondary to cerebellopontine angle tumor: A case report and brief overview

Trigeminal neuralgia (TN) is a paroxysmal shock-like pain restricted to innervations of the areas of one or more branches of the trigeminal nerve, often set off by light stimuli in a trigger zone. Pain attacks occur spontaneously and can also be triggered by a nonpainful sensory stimulus to the skin, intraoral mucosa surrounding the teeth, or tongue. The pathogenesis of TN is uncertain and typically is idiopathic, but it may be due to a structural lesion. Some pathologies include traumatic compression of the trigeminal nerve by neoplastic or vascular anomalies and intracranial tumors or demyelinating conditions such as multiple sclerosis. This case report describes an epidermoid cyst at the cerebellopontine angle in a 25-year-old young man with otherwise classical unilateral TN. The case highlights the difficulties of diagnosis and the importance of a multidisciplinary approach in making the correct diagnosis in symptomatic as well as classical TN.

Neuroanatomical Determinants of Secondary Trigeminal Neuralgia: Application of 7T Ultra-High-Field Multimodal Magnetic Resonance Imaging

BACKGROUND

Seven-Tesla (7T) magnetic resonance imaging (MRI) has demonstrated value for evaluating a variety of intracranial diseases. However, its utility in trigeminal neuralgia has received limited attention. The authors of the present study applied ultra-high field multimodal MRI to two representative patients with secondary trigeminal neuralgia due to epidermoid tumors to illustrate the possible clinical and surgical advantages of 7T compared with standard clinical strength imaging. Techniques included co-registration of multiple 7T sequences to optimize the detection of potential concurrent neurovascular and neoplasm-derived compression.

METHODS

7T MRI studies were performed using a whole body scanner. Two- and three-dimensional renderings of potential neurovascular conflict were created by co-registering time-of-flight angiography and T2-weighted turbo spin echo images in MATLAB and GE software. Detailed comparisons of the various field strength images were provided by a collaborating neuroradiologist (B.D.).

RESULTS

7T MRI clearly illustrated minute tumor-adjacent vasculature. In contrast, conventional, low-field imaging did not consistently provide adequate details to distinguish cerebrospinal fluid pulsatility from vessels. The tumor margins, although distinct from the trigeminal nerve fibers at 7T, blended with those of the surrounding structures at 3T. Two- and three-dimensional co-registration of time-of-flight angiography with T2-weighted MRI suggested that delicate, intervening vasculature may have contributed to these illustrative patients' symptomatology.

CONCLUSIONS

7T provided superior visualization of vital landmarks and subtle nerve and vessel features. Co-registration of various advanced 7T modalities may help to resolve complex disease etiologies. Future studies should explore the extent to which this dual etiology might persist across tumor types and utilize diffusion-based techniques to quantify what microstructural differences might exist between patients with trigeminal neuralgia from varying etiologies.

Stereotactic radiosurgery for trigeminal pain secondary to recurrent malignant skull base tumors

OBJECTIVE

The objective of this study was to assess outcomes after Gamma Knife radiosurgery (GKRS) re-irradiation for palliation of patients with trigeminal pain secondary to recurrent malignant skull base tumors.

METHODS

From 2009 to 2016, 26 patients who had previously undergone radiation treatment to the head and neck received GKRS for palliation of trigeminal neuropathic pain secondary to recurrence of malignant skull base tumors. Twenty-two patients received single-fraction GKRS to a median dose of 17 Gy (range 15-20 Gy) prescribed to the 50% isodose line (range 43%-55%). Four patients received fractionated Gamma Knife Extend therapy to a median dose of 24 Gy in 3 fractions (range 21-27 Gy) prescribed to the 50% isodose line (range 45%-50%). Those with at least a 3-month follow-up were assessed for symptom palliation. Self-reported pain was evaluated by the numeric rating scale (NRS) and MD Anderson Symptom Inventory-Head and Neck (MDASI-HN) pain score. Frequency of as-needed (PRN) analgesic use and opioid requirement were also assessed. Baseline opioid dose was reported as a fentanyl-equivalent dose (FED) and PRN for breakthrough pain use as oral morphine-equivalent dose (OMED). The chi-square and Student t-tests were used to determine differences before and after GKRS.

RESULTS

Seven patients (29%) were excluded due to local disease progression. Two experienced progression at the first follow-up, and 5 had local recurrence from disease outside the GKRS volume. Nineteen patients were assessed for symptom palliation with a median follow-up duration of 10.4 months (range 3.0-34.4 months). At 3 months after GKRS, the NRS scores (n = 19) decreased from 4.65 ± 3.45 to 1.47 ± 2.11 (p < 0.001); MDASI-HN pain scores (n = 13) decreased from 5.02 ± 1.68 to 2.02 ± 1.54 (p < 0.01); scheduled FED (n = 19) decreased from 62.4 ± 102.1 to 27.9 ± 45.5 mcg/hr (p < 0.01); PRN OMED (n = 19) decreased from 43.9 ± 77.5 to 10.9 ± 20.8 mg/day (p = 0.02); and frequency of any PRN analgesic use (n = 19) decreased from 0.49 ± 0.55 to 1.33 ± 0.90 per day (p = 0.08). At 6 months after GKRS, 9 (56%) of 16 patients reported being pain free (NRS score 0), with 6 (67%) of the 9 being both pain free and not requiring analgesic medications. One patient treated early in our experience developed a temporary increase in trigeminal pain 3-4 days after GKRS requiring hospitalization. All subsequently treated patients were given a single dose of intravenous steroids immediately after GKRS followed by a 2-3-week oral steroid taper. No further cases of increased or new pain after treatment were observed after this intervention.

CONCLUSIONS

GKRS for palliation of trigeminal pain secondary to recurrent malignant skull base tumors demonstrated a significant decrease in patient-reported pain and opioid requirement. Additional patients and a longer follow-up duration are needed to assess durability of symptom relief and local control.

The Tethered Effect of Vestibular Schwannoma Tumor Shrinkage Following Stereotactic Radiosurgery in Secondary Trigeminal Neuralgia

BACKGROUND

Compression of the trigeminal nerve by vessels and tumors causes trigeminal neuralgia. However, a tethering effect, provoking an abnormal root-stretching force, has been previously reported to play a role in trigeminal nerve hyperexcitability. We report 2 patients with vestibular schwannomas treated by stereotactic radiosurgery (SRS) who presented with typical manifestations of trigeminal neuralgia after tumor shrinkage. Furthermore, we discuss the mechanisms of trigeminal neuralgia.

CASE DESCRIPTION

Two patients without a history of trigeminal dysfunction, including trigeminal neuralgia, underwent SRS for vestibular schwannomas. Both patients demonstrated tumor shrinkage after transient tumor expansion following SRS. Neither patient presented with facial pain or dysesthesia at the time of peak tumor volume. However, trigeminal neuralgia occurred after tumor shrinkage. One patient underwent surgery, as the neuralgia was refractory to medical treatment; although the trigeminal nerve was adhered and tethered to the tumor, no neurovascular conflict was identified between the tumor and the nerve. We removed the tumor partially, dissecting between the nerve and the tumor, and relieved the tethered effect. Trigeminal neuralgia was relieved without medication after surgery.

CONCLUSIONS

The present cases demonstrate a tethered effect of tumor shrinkage after SRS, which was considered to play a role in trigeminal neuralgia. Surgical dissection surrounding the nerve root is effective for medically resistant neuralgia, even if the tumor shrinks. Partial tumor removal is adequate in such cases, as the tumor has been controlled by radiosurgery.

Petrous Face Meningiomas: Classification, Clinical Syndromes, and Surgical Outcomes

BACKGROUND

Petrous face meningiomas (PFMs) are challenging tumors because of their proximity to the cranial nerves, brainstem, and critical vasculature. The objective of this study is to present surgical outcomes and support an anatomic classification for PFM based on clinical presentation.

METHODS

A retrospective chart review was performed, and 51 PFMs were identified. Tumors were classified by location along the petrous face into anterior, middle, and posterior. Presentation and outcomes were analyzed with logistic regression.

RESULTS

The median follow-up was 31.6 months. Tumors were World Health Organization grade I (n = 50), with 1 World Health Organization grade II tumor. Location was anterior (22%), middle (14%), posterior (53%), and overlapping (12%). Median tumor diameter was 3.0 cm (range, 0.8-6.2 cm). Anterior location was associated with facial pain/numbness on presentation (P < 0.0001), middle location with hearing loss/vestibular dysfunction (P = 0.0035), and posterior with hydrocephalus (P = 0.0190), headache (P = 0.0039), and vertigo (P = 0.0265). Extent of resection was gross total (63%), near total (14%), and subtotal (25%). The observed radiographic recurrence rate was 15%. Mean progression-free survival after diagnosis was 9.1 years with 2-year, 5-year, and 10-year progression-free survival of 91.8%, 78.6%, and 62.9%, respectively. The complication rate was 27%. Age, location, and approach were not associated with complications.

CONCLUSIONS

PFMs present with distinct clinical syndromes based on their location along the petrous face: anterior with trigeminal symptoms, middle with auditory/vestibular symptoms, and posterior with symptoms of mass effect/hydrocephalous. Surgical resection is associated with excellent long-term survival and a low rate of recurrence, which can be managed with radiotherapy.

Trigeminal Neuralgia Secondary to Osteoid Osteoma of the Petrous Bone: Report of 4 Cases and Brief Review of Literature

OBJECTIVE

To retrospectively analyze clinical data of 4 patients with trigeminal neuralgia (TN) secondary to osteoid osteoma (OO) of the petrous bone and discuss treatment for this rare disease.

METHODS

Between January 2008 and December 2016, 4 patients in whom TN secondary to petrous bone OO was diagnosed received surgical treatment in Xuan Wu Hospital of Capital Medical University. We summarized the characteristics and treatments of this rare disease through retrospective review of the clinical information, imaging features, surgical details, and follow-up outcomes of the 4 patients.

RESULTS

Among the 4 patients, 2 were men; mean age was 39.3 ± 12.3 years (range, 26-52 years). All patients presented with symptoms of typical TN. Preoperative bone window computed tomography scan of the brain showed a regular bony lesion located at the petrous bone, contacting the trigeminal nerve. All patients experienced total relief of symptoms after surgical resection of the lesion by retrosigmoid sinus approach. During a mean follow-up of 14.2 months (range, 7-23 months), no preoperative symptoms recurred.

CONCLUSIONS

TN secondary to petrous bone OO is extremely uncommon. Surgical decompression is an effective treatment for patients with petrous bone OO and associated TN.

Microvascular Decompression for Treatment of Trigeminal Neuralgia in Patient with Facial Nerve Schwannoma

BACKGROUND

Secondary trigeminal neuralgia (TN) is uncommon. When a space-occupying lesion with mass effect is identified, the associated TN is often exclusively attributed to the tumor. This report illustrates the importance of considering coexistent actionable pathology when surgically treating secondary TN.

CASE DESCRIPTION

A 51-year-old woman presented with abrupt-onset TN of the V2 and V3 nerve divisions with hypesthesia. She denied changes in hearing, balance, or facial nerve dysfunction. Magnetic resonance imaging revealed a 1.6-cm contrast-enhancing cerebellopontine angle tumor that effaced the trigeminal nerve, consistent with a vestibular schwannoma. In addition, a branch of the superior cerebellar artery abutted the cisternal segment of the trigeminal nerve on T2-weighted thin-slice magnetic resonance imaging. Intraoperative electrical stimulation of the tumor elicited a response from the facial nerve at low threshold over the entire accessible tumor surface, indicating that the tumor was a facial nerve schwannoma. Considering the patient's lack of facial nerve deficit and that the tumor exhibited no safe entry point for intracapsular debulking, tumor resection was not performed. Working between the tumor and tentorium, a branch of the superior cerebellar artery was identified and decompressed with a Teflon pad. At last follow-up, the patient exhibited resolution of her TN. Her hearing and facial nerve function remained intact.

CONCLUSIONS

Despite obstruction from a medium-sized tumor, it is still possible to achieve microvascular decompression of the fifth cranial nerve. This emphasizes the importance of considering other actionable pathology during surgical management of presumed tumor-induced TN. Further, TN is relatively uncommon with medium-sized vestibular schwannomas and coexistent causes should be considered.

Clinical Features and Surgical Management of Cerebellopontine Angle Cholesteatoma That Presented as Trigeminal Neuralgia

BACKGROUND

It is difficult to differentiate patients with cerebellopontine angle (CPA) cholesteatoma and patients with primary trigeminal neuralgia just according to early symptoms. We aimed to explore the clinical characteristics, early diagnosis, and microneurosurgical techniques for CPA cholesteatoma that presented as trigeminal neuralgia.

METHODS

The data of 26 patients who complained trigeminal neuralgia with CPA cholesteatoma between January 2009 and December 2015 were collected and studied retrospectively, they were diagnosed by magnetic resonance imaging preoperatively and confirmed by pathology postoperatively. All the tumors were resected through a retrosigmoidal approach. In 26 cases, 14 patients who underwent cholesteatoma resection and microvascular decompression were assigned to group A and 12 patients who underwent only cholesteatoma resection were assigned to group B. The clinical features and surgical results between groups A and B were compared. The complications and surgical results were followed up, and surgical techniques were summarized.

RESULTS

All patients presented as trigeminal neuralgia at the same side of the cholesteatoma. There was no statistical difference between the 2 groups in clinical features and surgical results between groups A and B. All patients with cholesteatoma showed clear and significant imaging characteristics. The tumors were totally removed in 18 patients and subtotally removed in 8 patients. Pain relief was satisfactory in all patients. Surgical complications included transient aseptic meningitis in 2 patients, facial numbness in 2 patients, mild tinnitus in 2 patients, mild and facial weakness in 1 patient. No death, hematoma, or acute hydrocephalus were reported in this series. During the follow-up of 12-80 months, no patient experienced recurrence of pain or tumor.

CONCLUSIONS

Cholesteatoma of the cerebellopontine angle often presented as trigeminal neuralgia. Magnetic resonance imaging is helpful for early diagnosis according to its distinct signal. Surgical treatment is often the first choice, the neuralgia relief was satisfactory after operation. Microvascular decompression is recommended simultaneously if some offending vessels were founded during the surgical resection of the tumor.

Contralateral trigeminal neuralgia in a rapidly growing vestibular schwannoma: A case report

We present a rare case of vestibular schwannoma (VS) with contralateral trigeminal neuralgia. A 59 year-old woman presented with right-sided trigeminal neuralgia and a small VS in the left cerebellopontine angle (CPA) that was found via magnetic resonance imaging. The patient was administered medication; however, her symptoms gradually aggravated, and the size of the tumor increased. Two years after the initial diagnosis, the patient underwent surgical resection. After surgical resection, the patient's facial pain was improved. The trigeminal neuralgia appeared to be related to brainstem displacement caused by the contralateral VS. For VS with contralateral trigeminal neuralgia, surgical resection of the tumor should be considered as a possible treatment strategy.

Evaluating the utility of a scoring system for lipomas of the cerebellopontine angle

BACKGROUND

Cerebellopontine angle (CPA) lipomas are rare, benign, slow-growing masses. Resections are considered in symptomatic patients who are refractory to targeted medical therapies, but at those stages the lipomas have often reached considerable sizes and encompass critical neurovascular structures. The objective of this study is to develop and to evaluate the utility of a scoring system for CPA lipomas. The hypothesis is that CPA lipomas with lower scores are probably best managed with early surgery.

METHODS

The PubMed database was searched using relevant terms. Data on patient and lipoma characteristics were extracted and used to design a scoring system. CPA lipomas were stratified by scores with corresponding managements and outcomes analyzed.

RESULTS

One hundred and seventeen patients with CPA lipomas were identified and 40 CPA lipomas were scored. The remaining CPA lipomas were deficient in data and not scored. No lipomas were scored as 1. Score 2 lipomas (n = 12; 30%) most often underwent serial surveillances (n = 5; 41.6%), with the majority of symptoms remaining unimproved (n = 2; 40%). Patients with score 2 CPA lipomas treated with medical therapies (n = 3; 25%) often experienced symptom resolution (n = 2; 66.6%) (p = 0.0499). Patients with score 2 CPA lipomas undergoing surgical resections (n = 3; 25%) all experienced symptom resolution (n = 3; 100%) (p = 0.0499). Score 3 was most common (n = 16; 40%) and these lipomas were often surgically resected (n = 10; 62.5%). The majority of patients with score 3 CPA lipomas having undergone surgical resections (n = 10; 62.5%) experienced symptom improvement (n = 1; 10%) or resolution (n = 4; 40%).

CONCLUSIONS

Score 2 CPA lipomas are smaller and would be deemed non-surgical in general practice. However, our data suggest that these lipomas may benefit from either medical therapies or early surgical resections. The advantages of early surgery are maximal resection, decreased surgical morbidity, and improved symptom relief.

A Case of Bell's Palsy with an Incidental Finding of a Cerebellopontine Angle Lipoma

This case report illustrates the potential fallacy of attributing a patient's symptoms to an incidental finding. Serial imaging of small, asymptomatic cerebellopontine angle (CPA) lipomas is favored. It is imperative to accurately diagnose CPA lipoma on imaging and differentiate it from more common CPA lesions. We herein present a patient with symptoms consistent with Bell's palsy and an incidental finding of a CPA lipoma. Additionally, we performed a review of the literature for case reports of patients presenting with facial symptoms and diagnosed with a CPA lipoma.

Management of symptomatic hemifacial spasm or trigeminal neuralgia

Hemifacial spasm (HFS) or trigeminal neuralgia (TN) is a kind of hyperactivity disorder of cranial nerves caused by vascular compression. However, sometimes, the disease may arise from nerve damage produced by tumors, which was called as symptomatic HFS/TN. Until now, little is known about the exact mechanism and the necessity of microvascular decompression (MVD) regarding the tumor-induced HFS/TN, which is necessary to be retrospectively analyzed in a considerable sample. Among the 4021 patients who underwent MVD in our department between 2006 and 2014, 44 were finally diagnosed as symptomatic HFS or TN. These patients were focused in this study and their clinical features as well as intraoperative findings and postoperative outcomes were retrospectively investigated. Data analysis exhibited the symptomatic HFS/TN cases accounted for 1.1 % in the study, which were caused by epidermoid in 18 (40.9 %) and meningioma in 15 (34.1 %) followed by neuroma in 7 (15.9 %) as well as aneurysm in 2 (4.5 %) and arteriovenous malformation in 2 (4.5 %). Compared to those with idiopathic HFS/TN, younger females were more susceptible (p < 0.05). After resection of the neoplasm, the offending vessel was identified in 26 (59.1 %), which were followed by MVD process. Postoperatively, the symptoms relief rate was 88.6 %. Our study showed that surgical management of patients with symptomatic HFS/TN may lead to a satisfactory result, yet those primary lesions should be removed firstly. In some cases, a microvascular decompression process might be unnecessary afterward, but the entire nerve root should be checked to exclude any vessel in contact with.

Cerebellopontine angle epidermoid cysts: clinical presentations and surgical outcome

Epidermoid cysts constitute less than 1% of intracranial tumors with the majority of them involving cerebellopontine angle (CPA). Although several mechanisms for cranial nerve dysfunction due to these tumors have been proposed, no direct evaluation for hyper- or hypoactive dysfunction has been done. In this case series, pathophysiology of cranial nerve dysfunction in CPA epidermoid cysts was evaluated with special attention to a new mechanism of capsule strangulation caused by stratified tumor capsule. Twenty-two cases with epidermoid cysts of CPA micro-neurosurgically treated in our departments since 2005 were reviewed. Clinical status of the patients before the surgery and post-operative functional outcome were recorded. Available data from the English literature were summarized for comparison. Mass reduction of cyst contents in most cases was usually associated with prompt and marked improvement of the symptoms suggesting neuroapraxia caused by compression of the tumor content and/or mild ischemia. Among them, two cases showed strangulation of the affected nerves by the tumor capsule whose preoperative dysfunction did not improve after surgery in spite of meticulous microsurgical removal of the lesion. Involved facial and abducent nerves in these two cases showed distortion of nerve axis and nerve atrophy distal to the strangulation site. We report the first direct evidence of etiology of cranial nerve dysfunction caused by cerebellopontine angle epidermoid tumors. Young age and rapidly progressive neurological deficit might be the characteristics for strangulation of the affected nerves by the cyst capsule. Even though the number of cases might be limited, immediate decompression and release of the strangulating band might be urged in such patients to prevent irreversible deficits.

Case Report: Trigeminal Neuralgia Caused by a Minute Meningioma with Hyperostosed Suprameatal Tubercle

Cerebellopontine angle tumors might occasionally provoke trigeminal neuralgia but are usually large enough to be diagnosed radiographically. We present a case of trigeminal neuralgia caused by a very small meningioma covering the suprameatal tubercle that displayed hyperostosis at the entrance of Meckel's cave and was not obvious on routine magnetic resonance (MR) images. A 72-year-old woman with intractable trigeminal neuralgia in the left V3 territory was referred to our institution. Preoperative imaging studies revealed that the left trigeminal nerve was medially distorted at the entrance of Meckel's cave by a laterally seated bone bulge covered by a minute enhanced lesion. Trigeminal nerve decompression surgery was performed via a retrosigmoid intradural suprameatal approach. We found a small meningioma that had compressed and flattened the trigeminal nerve root at the entrance of Meckel's cave, which was grossly and totally removed by suprameatal tubercle resection. There was no vascular compression of the trigeminal nerve root. The trigeminal neuralgia ceased completely after the operation. Accurate preoperative determination of the causative pathologies is essential to achieve adequate surgical results after microvascular decompression for neurovascular compression syndrome. Because conventional MR sequences are inadequate for the precise interpretation of complex neurovascular anatomy in the cerebellopontine angle and such small tumors can be overlooked on routine MR studies, high-resolution thin-slice MR examinations and careful radiological interpretations are required for correct diagnosis and treatment.

Fully endoscopic retrosigmoid approach for posterior petrous meningioma and trigeminal microvascular decompression

BACKGROUND

Cerebellopontine angle tumor resection and cranial nerve microvascular decompression are usually performed with the aid of the surgical microscope. The endoscope is commonly used as an adjuvant.

METHOD

A retrosigmoid craniectomy is done. Upon dural opening, the endoscope is inserted into the operative field along the petrotentorial junction. Cerebrospinal fluid drainage provides a wider space for introduction of the endoscope and surgical instruments. Traditional microsurgical techniques are used during the entire procedure.

CONCLUSION

A fully endoscopic retrosigmoid approach is a safe and effective procedure for cerebellopontine angle tumor resection and cranial nerve microvascular decompression.

KEY POINTS

• Careful examination of preoperative studies is needed to identify anatomical peculiarities. • Patient positioning: the head must be gently flexed and its vertex gently tilted toward the floor. • Neurophysiologic monitoring and intraoperative navigation. • Craniectomy: partial exposure of the transverse and sigmoid sinuses. • Curvilinear dural incision reflected laterally to minimize the risk of sinus injury. • Opening the cerebellomedullary cistern for CSF drainage and cerebellar relaxation. • Dynamic endoscopy enhances depth perception and must be performed by a team with experience in endoscopic intracranial surgery. • Traditional microsurgical techniques have to be applied during the entire operation. • Multilayer reconstruction, including watertight dural closure. • Meningiomas causing brainstem shift are not suitable for endoscopic resection.

Therapeutic efficacy and safety of botulinum toxin type A in trigeminal neuralgia: a systematic review

Trigeminal neuralgia is a common disorder caused mainly by compression of the trigeminal nerve root by an overlying blood vessel. Pharmacotherapy and surgery are ineffective or unsuitable in many patients. Therefore, other therapeutic modalities have been tried, including injection of botulinum toxin type A (BTX-A). This study aims to systematically review the therapeutic efficacy and safety of BTX-A in trigeminal neuralgia. PubMed, EMBASE, Cochrane Library Clinical Trials and Web of Science from January 1966 to March 2013 were searched with the terms of “botulinum toxin” AND “trigeminal neuralgia”, and references of related articles were traced. Data on the efficacy and safety of BTX-A in this disorder were extracted and analyzed by at least 2 reviewers. Data for individual studies were reported, and pooled data were analyzed if appropriate. Five prospective studies and one double-blind, randomized, placebo-controlled study were identified. Response was achieved in approximately 70-100% of patients, and the mean pain intensity and frequency were reduced by approximately 60-100% at 4 weeks after treatment in most studies. Major adverse events were not reported. Available studies show BTX-A may be effective in treatment of trigeminal neuralgia. However, well-designed randomized, controlled, double-blinded trial is still lacking. Future BTX-A treatment studies on optimal dose, duration of the therapeutic efficacy, common AEs, and the time and indications for repeat injection would be promising.