Gamma knife radiosurgery for cerebellopontine angle epidermoid tumors

Role of stereotactic radiosurgery for intracranial epidermoid tumors: a systematic review to assess its safety, efficacy, and complication profile

BACKGROUND

Even a gross total resection of a benign epidermoid tumor (ET) carries a high risk of recurrence. The management strategy mostly involves redo surgical excision but at a significant cost of morbidity and mortality. The role of adjuvant radiation therapies in this scenario is still undefined.

OBJECTIVE

To evaluate the feasibility, safety, efficacy, and complication profile of radiosurgery as a standalone or adjuvant therapy for intracranial epidermoid in the published literature.

METHODOLOGY

Following PRISMA guidelines, a comprehensive search of the databases PubMed, Embase, Scopus, and Web of Science in published English language was conducted. We included studies with radiosurgery for benign ET and in patients with malignant transformation of ET (MTET). All studies were evaluated for tumor characteristics, pattern of treatment, dosimetric profile, outcome, and complications. We included all studies with at least one outcome of interest i.e. local control (LC); progression-free survival (PFS); symptomatic toxicity; disease progression; retreatment; and overall survival (OS); and cause-specific mortality.

RESULTS

The search revealed 403 articles, of which 6 and 8 studies with patients of benign ET and MTET respectively were included. 25 (65.7%) patients received primary SRS. 27 patients presented with hyperactive cranial nerve syndromes; 77.7% gained complete improvement. The overall median age was 46.7 years (22-67) and the median tumor volume ranged from 0.38 to 6.2cc in benign ET. Volumetric reduction was seen in 6 cases; progression was seen in 2 cases while ET remained stable in the rest. Mean follow-up duration ranged from 33.7 to 60 months, and no recurrence was reported at the latest follow-up in any case of benign ET. 9.5% of patients suffered from transient cranial nerve deficits with no prolonged adverse radiation effect. OS in the MTET group was 6 to 60 months following GKRS with 50% of patients alive at the latest follow-up.

CONCLUSION

SRS may be a promising treatment option for a conventionally benign and radioresistant ET making a meaningful change in the natural history of the disease. It is a valuable adjuvant technique in patients with MTET.

Optimizing Surgical Outcomes for Intracranial Epidermoid Tumors: A Retrospective Analysis of Clinical Predictors, Surgical Decisions, and Patient Clustering

BACKGROUND/OBJECTIVE

Intracranial epidermoid tumors (ETs) are rare, benign lesions that present significant challenges in neurosurgical management due to their propensity to encase vital neurovascular structures. We aimed to evaluate the impact of clinical, demographic, and tumor-specific factors on surgical decisions (gross total resection [GTR] vs. subtotal resection [STR]) and outcomes and identify patient clusters with distinct profiles and outcomes post-resection.

METHODS

We retrospectively analyzed 72 patients with ET treated from 1998 to 2022, employing multivariable logistic regression for GTR versus STR predictors and Kaplan-Meier curves for progression-free survival (PFS). K-prototype clustering classified patients based on clinical data.

RESULTS

The mean age of our cohort was 39.8 ± 20.1 years. About 13.9% of patients had a recurrence, with a median PFS of 108 months (interquartile range: 57 -206). Seizures significantly predicted GTR (P < 0.05), whereas adherence to critical structures reduced GTR likelihood (P < 0.05). Initial surgeries more often achieved GTR, correlating with longer PFS (P < 0.0001) and reduced recurrence (P < 0.01) versus re-operations. Cluster analysis identified three distinct groups, with the initial GTR cluster showing superior PFS and the lowest recurrence (P < 0.0001 and P < 0.01, respectively). Statistically significant predictors of PFS included age and preoperative seizure presence, with older age favoring longer PFS (P < 0.01) and seizures associated with reduced PFS (P < 0.01). In addition, patients with previous surgeries showed a trend toward shorter PFS (P < 0.05).

CONCLUSIONS

This study emphasizes the importance of tailored surgical strategies in managing intracranial ETs, advocating for GTR to optimize long-term outcomes where possible. Future prospective studies are essential to further refine treatment approaches, enhancing survival for ET patients.

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.

Gamma knife radiosurgery of epidermoid tumors: an analysis of treatment results of eight patients

Background

Epidermoid tumors (ETs) of the central nervous system (CNS) are rare tumors that typically occur in the 4^th decade. They typically grow around vital neurovascular structures which makes surgical treatment difficult. The objective of this paper is to report on the effectiveness and safety in the management of epidermoid tumors with gamma knife surgery (GKS).

Materials and methods

This is a retrospective study of the medical records of 8 patients treated with GKS for epidermoid tumors between July 2010 to June 2019. The median prescription dose was 11 Gy, ranging from 10 to 12 Gy, 5 patients received the total dose target to the 50% line and 3 to the 55% isodose line. The mean tumor volume was 12.4 cc ranging from 4.4 to 24.8cc. The median follow-up time was 33.7 months and ranged from 0.9 to 58.8 months. At follow-up, patients were evaluated for neurological signs and symptoms and radiographic evidence of progression of disease. Two patients were treated after failure of linac stereotactic radiosurgery. One patient underwent stereotactic radiosurgery prior to GKS, and the other had failed surgical resection prior to GKS.

Results

The median age was 33 years old. There were two males and six females. The most common presenting manifestation was headaches followed by vision and hearing problems. Symptoms were resolved in all cases, except for one who had partial control of trigeminal neuralgia. All patients were locally controlled by imaging and neurological examination at first follow-up.

Conclusion

Gamma knife surgery is a safe and effective alternative treatment in patients with CNS epidermoid tumors and should be included in the initial recommendation.

Analysis of Giant Intraventricular and Extraventricular Epidermoids, Defining Risk Factors for Recurrence, an Institutional Experience

Background:

Multicompartmental intraventricular epidermoids behave differently from multicompartmental extraventricular lesions and localized lesions during its management. Few studies are available which have analyzed risk factors separately in these groups of cases for recurrence of these lesions and time to recur.

Materials and Methods:

In this retrospective observational study, 72 cases of intracranial epidermoid were treated over a span of 7 years. Cases were categorized into three groups. Group 1 comprised 15% (11/72) of cases with intraventricular multicompartmental, Group 2 with 22% (16/72) extraventricular giant tumors with multicompartmental involvement and size >4.5 cm, and Group 3 comprised 63% (45/72) of patients with lesions <4.5 cm and localized. Data pertaining to demography, clinical and radiological features, surgery performed, postoperative complication, histology, and follow-up were obtained from medical records available in the institute.

Results:

The average duration to treat was 1.86 ± 0.52 (standard deviation [SD]) years, with headache as a major complaint in all the groups. Combined endoscope-assisted microsurgery was performed in 38.8% (28/72), microsurgery in 54.1% (39/72), and endoscopic excision in 6.9% (5/72) of cases. Tumor calcification was found in 23.6% (17/72) and preoperative capsular enhancement was seen in 19.4% (14/72) which persisted in 79% (11/14) of cases postoperatively on subsequent follow-up suggesting recurrence. On stepwise logistic regression analysis, preoperative capsular enhancement was a strong predictor of recurrence of tumor (P = 0.001). The average follow-up was 46 ± 14.92 (SD) months in Group 1, 52.34 ± 11.45 (SD) months in Group 2, and 63.36 ± 18.42 (SD) months in Group 3.

Conclusion:

Although the intracranial epidermoid is known to recur after long interval, tumor with specific characteristics can recur in short span of 5–6 years. Tumor characteristics such as preoperative capsular enhancement, multicompartmental distribution in vertebrobasilar territory, large size, and presence of calcification are strong predictors for recurrence. Performing endoscope-assisted microsurgery can decrease the postoperative morbidities but does not reduce the recurrence risk.

CT cisternography to visualize epidermoid tumors for stereotactic radiosurgery treatment planning

The visualization of intracranial epidermoid tumors is often limited by difficulties associated with distinguishing the tumor from the surrounding cerebrospinal fluid using traditional computed tomography (CT) or magnetic resonance imaging (MRI) modalities. This report describes our experience using CT cisternography to visualize intracranial epidermoid tumors in three illustrative cases. CT cisternography of the epidermoid tumor provides more clarity and precision compared to traditional neuroimaging modalities. We demonstrate the feasibility of using CT cisternography to produce high-resolution images with well-defined tumor margins that can be used effectively for precise SRS treatment planning.

Radiosurgery for Epidermoid Tumors: Dramatic Pain Relief from Trigeminal Neuralgia

Purpose 

The purpose of this study is to discuss the long-term effects of radiosurgery for epidermoid tumors, including the symptoms of trigeminal neuralgia and/or facial spasm, which we have originally reported before.

Background

Intracranial epidermoids are slow-growing tumors that can become symptomatic once they develop into large tumors. The mainstay of the treatment is surgery. However, eradicating the whole tumor is often difficult and some tumors may recur. In addition to their mass effects on the brain, these tumors are often associated with hyperactive nerve dysfunction syndromes such as trigeminal neuralgia, glossopharyngeal neuralgia, and/or facial spasm.

Cases and methods 

We report 13 cases of epidermoid tumors, 12 of which were located in the cerebellopontine angle (CPA), which were treated using 14 radiosurgery procedures. The inclusion criteria for radiosurgery were the presence of well-localized small tumors and/or severe associated neuralgia or facial spasms. The mean target volume ranged from 0.17 to 9.5 cm³ with a mean of 2.85 cm³. The lesions were treated with a mean maximum and a marginal dose of 28.2 Gy and 14.2 Gy, respectively.

Results

Among the 14 gamma knife procedures that were performed in 13 patients, dose planning to ensure total and partial coverage for relief from hyperactive cranial nerve dysfunction (HCND) was performed. Six cases were totally and another eight were partially covered at the dose planning. The irradiated tumors showed a minor decrease or no remarkable changes during a mean follow-up period of 86.1 months. Tumor progression requiring a second surgery was seen in two cases. The trigeminal neuralgias either improved or disappeared soon after the procedure, enabling the discontinuation of the medication.

Conclusion 

Radiosurgery led to a dramatic improvement in HCND. In fact, the immediate cure of neuralgia after the radiosurgery was observed in several cases, even after partial coverage with radiosurgery. The interface between the tumor and the nerve was the main target. The definite mechanisms for this favorable outcome have not been verified yet, but the functional modulation by the radiosurgery could be one. Electrophysiological alteration at the interface between the tumor and nerve has been considered. When the tumors were totally covered with radiosurgery, persistent tumor control was expected. Sufficient tumor control is possible if the tumor can be covered entirely with radiosurgery. Functional modulation of trigeminal neuralgia and facial spasms can also be attained even by partial dose planning for the nerve-tumor interface.