Hypervascular Lesions of the Cerebellopontine Angle: The Relevance of Angiography as a Diagnostic and Therapeutic Tool and the Role of Stereotactic Radiosurgery in Management. A Comprehensive Review

Usefulness of posterior transpetrosal approach for the large solid cerebellopontine angle hemangioblastoma fed from multiple blood supplies: A technical case report

Background

Extra-axial cerebellopontine angle (CPA) hemangioblastomas are rare clinical entity and surgical treatment is challenging due to the anatomical difficulties and multi-directional blood supplies. On the other hand, the risk of endovascular treatment for this disease has also been reported. Herein, we successfully applied a posterior transpetrosal approach to remove a large solid CPA hemangioblastoma without preoperative feeder embolization.

Case Description

A 65-year-old man presented with a complaint of diplopia during downward gaze. Magnetic resonance imaging revealed a solid tumor with homogeneous enhancement measuring about 35 mm at the left CPA, and the tumor compressed a left trochlear nerve. Cerebral angiography disclosed tumor-staining fed by both left superior cerebellar and left tentorial arteries. After the operation, the patient's trochlear nerve palsy improved dramatically.

Conclusion

This approach offers more optimal surgical working angle to the anteromedial part compared to the lateral suboccipital approach. In addition, the devascularization from the cerebellar parenchyma can be performed more reliably than the anterior transpetrosal approach. After all, this approach can be particularly useful when vascular-rich tumors receive blood supplies from multiple directions.

Successful preoperative embolization of a cystic-solid variant of cerebellopontine angle hemangioblastoma

Tumors of the cerebellopontine angle (CPA) represent an heterogeneous group which can arise extradural, intradural-extraaxial or intraaxial compartment. Hemangioblastomas of the cerebellopontine angle (CPA) are extremely rare. Computed tomography (CT) and magnetic resonance imaging (MRI) are often the gold-standard radiological imaging modalities used in characterizing the lesion's features, and its relationship with the surrounding structures. They are vascular lesions and may cause profuse bleeding intraoperatively, that is why angiography remains a crucial diagnostic and therapeutic tool, by reducing both the presurgical differential diagnosis, as well as the intraoperative bleeding by providing capability of embolization of this vascular tumor. We present the case of a 65 year old patient with a cystic-solid variety of HMB at the right CPA, which was successfully treated by a combination of an endovascular preoperative embolization and surgery without major complications or neurological deficits.

Treatment of Residual, Recurrent, or Metastatic Intracranial Hemangiopericytomas With Stereotactic Radiotherapy Using CyberKnife

Purpose

Hemangiopericytomas are aggressive tumors known for their recurrence. The purpose of this study was to evaluate the management of residual, recurrent, and metastatic intracranial hemangiopericytomas using CyberKnife (CK) stereotactic radiotherapy (SRT).

Materials and Methods

Data were collected from 15 patients (28 tumors; eight men and seven women; 32–58 years) with residual, recurrent, or metastatic intracranial hemangiopericytomas, who were treated with stereotactic radiotherapy using CyberKnife between January 2014 and August 2019. All patients had previously been treated with surgical resection. Initial tumor volumes ranged from 0.84 to 67.2 cm³, with a mean volume of 13.06 cm³. The mean marginal and maximum radiosurgical doses to the tumors were 21.1 and 28.76 Gy, respectively. The mean follow-up time for tumors was 34.5 months, ranging from 13 to 77 months.

Results

15 patients were alive after treatment; the mean post-diagnosis survival at censoring was 45.6 months (range 13–77 months). The volumes of the 28 tumors in the 15 followed patients were calculated after treatment. Postoperative magnetic resonance imaging revealed a mean tumor volume of 6.72 cm³ and a range of 0–67.2 cm³, with the volumes being significantly lower than pretreatment values. Follow-up imaging studies demonstrated tumor disappearance in seven (25%) of 28 tumors, reduction in 14 (50%), stability in one (3.57%), and recurrence in six (21.4%). Total tumor control was achieved in 22 (78.5%) of 28 tumors. The tumor grade and fraction time were not significantly associated with progression-free survival. Intracranial metastasis occurred in three patients, and extraneural metastasis in one patient.

Conclusions

On the basis of the current results, stereotactic radiotherapy using CyberKnife is an effective and safe option for residual, recurrent, and metastatic intracranial hemangiopericytomas. Long-term close clinical and imaging follow-up is also necessary.

Diagnostic challenges of posterior fossa hemangioblastomas: Refining current radiological classification scheme

Hemangioblastomas (HBMs) are known to exhibit very typical radiological features and thus classified by well-established radiological classification scheme. We reviewed our series of posterior fossa HBMs in order not only to evaluate the relevance of current classification scheme, but also to possibly refine it. Also, we added descriptions on several cases with unusual radiological magnetic resonance imaging (MRI) findings in which differential diagnosis was challenging. We retrospectively reviewed preoperative MRI of 118 patients with pathologically diagnosed posterior fossa HBMs at our institution between 2002 and 2015. Total 128 tumors were included to this study and classified into four categories based on the presence and nature of cystic components: extratumoral cystic (Type Ce, classical cystic with a mural nodule), intratumoral cystic (Type Ci), mixed cystic (Type Cm), and solid (Type S). The association with von Hippel-Lindau (VHL) disease was also investigated. In 118 patients (65 male and 53 female), 79 (66.9%) had solitary HBMs and 39 (33.1%) were diagnosed with VHL disease. Type Ce with typical radiological findings was the most prevalent type of HBM (63.3%), followed by Type S (21.1%). HBMs with intratumoral cysts were uncommon (Type Ci, 11.7%) and mixed extratumoral and intratumoral cysts (Type Cm) accounted for only 3.9%. No intergroup differences were observed in the proportions of each subtype between the solitary and VHL disease-associated HBMs. The blood loss was much lower in Type Ce than in other subtypes. In Type Cm, radical resection was often challenging as the differentiation between intratumoral and extratumoral cysts was difficult resulting in incomplete resection. Refined radiological classification scheme is more practical because it does not only help surgeons determine whether the cystic wall should be removed or not, but also covers cases with atypical radiological presentations. For solid and extraparenchymal HBMs, differential diagnosis is more difficult as well as very critical as surgical removal is often very challenging.

Hemangioblastoma of the Cerebellopontine Angle Evaluated with Pseudocontinuous Arterial Spin Labeling

Hemangioblastomas of the cerebellopontine angle (CPA) that emerge extra-axially from the peripheral nervous system are extremely rare. We report a case of hemangioblastoma of the CPA evaluated by pseudocontinuous arterial spin labeling (pCASL). The high rate of tumor blood flow determined using pCASL provided additional useful information for the differential diagnosis of the CPA tumors in this patient.

Nervous System Hemangiopericytoma

The management of patients harboring central nervous system (CNS) hemangiopericytomas (HPCs) is a partially answered challenge. These are rare locally aggressive lesions, with potential for local recurrence, distal neural metastasis (DNM), and extraneural metastasis (ENM). Resection, when feasible, remains the initial treatment option, providing histological diagnosis and immediate relief of tumor-related mass effect. Patients receiving surgery alone or surgery and external beam radiotherapy (EBRT) show improved overall survival (OS) and progression-free survival as compared to those undergoing a biopsy alone (p = 0.01 and p = 0.02, respectively). Yet, in many instances, patient and tumor-related parameters preclude complete resection. EBRT or stereotactic radiosurgery (SRS) shares a significant role in achieving local tumor control, not shown to impact OS in HPC patients. The benefits of SRS/EBRT are clearly limited to improved local tumor volume control and neurologic function, not affecting DNM or ENM development. SRS provides acceptable rates of local tumor volume control coupled with treatment safety and a patient-friendly apparatus and procedure. Single-session SRS is most effective for lesions measuring <2 cm in their largest diameter (10 cm3 volume), with prescription doses of at >15 Gy. Systemic HPC disease is managed with various chemotherapeutic, immunotherapeutic, and anti-angiographic agents, with limited success. We present a short discussion on CNS HPCs, focusing our discussion on available evidence regarding the role of microsurgical resection, EBRT, SRS, chemotherapy, and immunotherapy for upfront, part of adoptive hybrid surgery approach or for recurrent HPCs.

Staged multi-modality treatment approaches for giant cerebellopontine angle hemangioblastomas

Giant hemangioblastomas (HBs) located in the cerebellopontine angle (CPA) present rare, high risk neurosurgical challenges. En bloc resection has been traditionally recommended for HBs, however this approach may pose unacceptable risk with giant tumors. Alternative treatment strategies have not been well described and the relevant literature is scant. This case review includes an illustrative patient with a giant, symptomatic CPA HB. It was felt that the neurovascular and tumor attributes were favorable for a multi-modality treatment strategy rather than circumferential dissection to remove this formidable tumor. A staged approach consisting of preoperative HB devascularization, debulking and piecemeal resection followed by radiosurgery for a small residuum produced an excellent clinical outcome. Variations of this unconventional multi-modality strategy may reduce the perioperative morbidity of carefully selected patients with giant CPA HBs. A thorough literature review is provided.

Unusual case of hemangioblastoma of the cerebellopontine angle

Background:

Hemangioblastomas are the most common primary tumor of the posterior fossa. There are few cases of hemangioblastoma of the cerebellopontine angle (CPA). When present in this location, hemangioblastoma presents a diagnostic challenge as its imaging findings closely resemble those of vestibular schwannoma (VS), which is much more common in the CPA.

Case Description:

We report the case of a 42-year-old man presenting with vertigo and diplopia found to have a CPA tumor with imaging resembling VS. He underwent retrosigmoidal resection of his tumor, which was found to be a hemangioblastoma.

Conclusion:

Hemangioblastoma, though rare in the CPA, should be considered in the differential diagnosis of CPA tumors.