Cavernous Malformation From Cranial Nerves: A Systematic Review With a Novel Classification and Patient-Level Analysis

BACKGROUND AND OBJECTIVES

Cavernous malformations (CMs) occurring in the cranial nerve (CN) are extremely rare, and there is currently no comprehensive review on CN CMs, leading to a lack of sufficient understanding of CN CMs. We aimed to systematically review all published CN CM cases; summarize the epidemiology, clinical manifestations, treatment, and prognosis of CN CMs; and identify factors influencing the prognosis of CN CMs.

METHODS

This systematic review identified all cases potentially diagnosed with CN CM through a systematic search of PubMed, SCOPUS, Web of Science, and Cochrane databases. This represents the most comprehensive systematic review to date. We classified CN CMs based on their anatomic origins. Patient characteristics, disease manifestations, treatment approaches, and prognosis were summarized descriptively. Further analysis was conducted to identify factors influencing the prognosis of CN CMs.

RESULTS

The final analysis included 108 articles (127 individual patient cases). The optic nerve (49/128, 38.3%) is the most commonly affected nerve. Notably, CN CMs can be categorized into 3 types: Intraneural, Perineural, and Extraneural. Preoperative nerve function status and novel classification were associated with the prognosis of CN CMs (P = .001; P < .001). The postoperative neurological deterioration rate for the Intraneural type was 19/37 (51.4%); for the Extraneural type, it was 13/69 (18.8%); and for the Perineural type, it was 1/22 (4.5%) (P < .001).

CONCLUSION

We reviewed all the published CN CMs to date, offering a comprehensive description of CN CMs for the first time and identifying prognostic factors. The classification of CN CMs proposed in this study could serve as guidance for the selection of intraoperative treatment regimens. The findings of this systematic review are expected to provide a foundation for clinical decision-making in this crucial rare disease and lay the groundwork for developing relevant clinical guidelines.

Cystic Cerebral Cavernous Malformations: Report of Five Cases and a Review of Literature

Introduction  Cerebral cavernous malformations (CCMs) account for about 5 to 13% of intracranial vascular malformations. Cystic cerebral cavernous malformations (cCCMs) are a rare morphological variant and can cause diagnostic and therapeutic dilemmas. We describe our five such cases and review the existing literature on this entity. Methods  A search of the PubMed database for cCCMs was done, and all articles in English emphasizing the reporting of cCCMs were selected. A total of 42 publications describing 52 cases of cCCMs were selected for analysis. Epidemiological data, clinical presentation, imaging features, the extent of resection, and outcome were analyzed. Radiation-induced cCCMs were excluded. We have also described five of our cases of cCCMs and reported our experience. Results  The median age at presentation was 29.5 years. Twenty-nine patients had supratentorial lesions, 21 had infratentorial lesions, and 2 had lesions in both compartments. Among our four patients, three had infratentorial lesions, whereas one had a supratentorial lesion. Multiple lesions were seen in four patients. A majority (39) had symptoms of mass effect (75%), and 34 (65.38%) had raised intracranial pressure (ICP), whereas only 11 (21.15%) had seizures. Among our four operated patients, all of them had symptoms of mass effect, and two of them also had features of raised ICP. The extent of resection was gross total in 36 (69.23%), subtotal in 2 (3.85%), and not reported in 14 (26.93%). All four of our operated patients underwent gross total resection, but two of them underwent a second surgery. Of the 48 patients in whom the surgical outcome was reported, 38 improved (73.08%). One showed a transient worsening followed by improvement, one developed a worsening of the pre-existing focal neurological deficit (FND), two developed a new FND, and 5 had no improvement in their FNDs. Death occurred in one patient. All four of our operated patients improved after surgery, although three of them showed a transient worsening of FNDs. One patient is under observation. Conclusion  cCCMs are rare morphological variants and can cause considerable diagnostic and therapeutic dilemmas. They should be considered in the differential diagnosis of any atypical cystic intracranial mass lesion. Complete excision is curative, and the outcome is generally favorable; although transient deficits may be seen.

The effect of morphological variability of Dorello's canal on surgical procedures - a review

Dorello's canal is an arched structure of bone-fibrous character located in the petroclival venous confluence atop the petrosal bone in the petroclival region. It is bordered by the petrosphenoidal ligament, the petrous part of the temporal bone and the lateral border of the upper part of clivus. Its content in the vast majority of variants comprises the abducens nerve, the inferior petrosal sinus, the venous drainage and the dorsal meningeal artery or its medial branch. With the development of microsurgical techniques, this area has gained huge clinical importance, mainly concerning the order in which the above-mentioned elements (especially the position of the abducens nerve) are arranged in relation to each other. These structures appear in different variant forms and necessitate an individual clinical approach. The main purpose of this review is to present condensed information about possible intercorrelations among them and to indicate, on the basis of the available literature and research, possible surgical approaches and the need to consider the variability when treatments in this region are planned.

An isolated cavernous malformation of the sixth cranial nerve: A case report and review of literature

Background

Isolated cavernous malformation (CM) of the abducens nerve has not been reported in the literature. Herein, the authors address the clinical importance of these lesions and review the reported cases of CM from 2014 to 2020.

Case Description

A 21-year-old man presented with binocular diplopia and headache from 2 months before his admission. The neurological examination revealed right-sided abducens nerve palsy. The brain MRI revealed an extra-axial pontomedullary lesion suggestive of a CM. The lesion was surgically removed. During the operation, the abducens nerve was resected considering the lesion could not be separated from the nerve and an anastomosis was performed using an interposition nerve graft and fibrin glue. Pathological examination of the resected lesion revealed that it was originated from within the nerve. The patient's condition improved in postoperative follow-ups.

Conclusion

Surgical resection of the cranial nerves CMs is appropriate when progressive neurological deficits are present. If the lesion is originated from within the nerve, we suggest resection of the involved nerve and performing anastomosis. Novel MRI sequences might help surgeons to be prepared for such cases and fibrin glue can serve as an appropriate tool to perform anastomosis when end-to-end sutures are impossible to perform.

Functional outcome after surgical treatment of cavernous malformation involving ocular motor cranial nerves: A systematic review

Cavernous malformations (CMs) of cranial nerves (CN) III, IV, and VI are extremely rare, and limited studies have assessed functional outcomes after treatment. This systematic review investigated the clinical features of CMs in ocular motor CNs, including the treatment results, and compared different surgical methods for functional preservation of ocular motor CNs. 'PubMed', 'SCOPUS', 'Web of Science', and 'Google Scholar' databases were searched to identify case reports and studies published between January 1980 and December 2018. This systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Twenty-seven patients were identified (median age, 46 years; range, 3 months-71 years). CN III was involved in 17 patients (63.0%), CN IV in 8 (29.6%), and CN VI in 2 (7.4%). Treatments included gross total resection (GTR) and nerve transection in 6 patients (22.2%), GTR and nerve continuity preservation in 7 (25.9%), subtotal resection (STR) and nerve continuity preservation in 4 (14.8%), GTR and end-to-end anastomosis in 5 (18.5%), and conservative care in 3 (11.1%), while the treatment method for 2 (7.4%) patients has not been described in the literature. In 22 patients who underwent surgical treatment, functional changes included improvement in 9 patients (40.9%), no change in 10 (45.5%), and worsening symptoms in 3 (13.6%). Functional preservation was achieved in 12 (54.5%) of the 22 patients; the nerve continuity preservation method conferred a significant advantage for functional preservation compared with other surgical methods (p = 0.004). Functional preservation of ocular motor CNs can be achieved by nerve continuity preservation.

Supernumerary Abducens Nerves: A Comprehensive Review

BACKGROUND

Branching and/or replication of the abducens nerve is not an uncommon occurrence. Although numerous variations have been documented, the rarest forms are duplicated or triplicated nerves, where multiple nerve roots originate from the brainstem, travel intracranially, and attach to the lateral rectus as separate entities.

METHODS

We conducted a systematic literature search on the topic of supernumerary abducens nerve, using PubMed and Google Scholar.

RESULTS

After screening, 16 studies were included: 11 cadaveric studies and 6 case reports.

CONCLUSIONS

In this paper, we review the literature on variations found, discuss current hypotheses and clinical relevance, and propose future studies. Neurosurgeons should be aware of such nerve variants when viewing imaging or operating in the regions traversed by the abducens nerve.

Angiographically occult vascular malformation of the intracranial accessory nerve: case report

Angiographically occult cerebral vascular malformations (AOVMs) are usually found in the supratentorial brain parenchyma. Uncommonly, AOVMs can be found within the cavernous sinus or basal cisterns and can be associated with cranial nerves. AOVMs involving the intracranial segment of the spinal accessory nerve have not been described. A 46-year-old female patient presented with a history of episodic frontal headaches and episodes of nausea and dizziness, as well as gait instability progressing over 6 months prior to evaluation. Imaging revealed a well-circumscribed 3-cm extraaxial T1-weighted isointense and T2-weighted hyperintense contrast-enhancing mass centered in the region of the right lateral cerebellomedullary cistern. The patient underwent resection of the lesion. Although the intraoperative appearance was suggestive of a cavernous malformation, some histological findings were atypical, leading to the final diagnosis of vascular malformation, not otherwise specified. The patient's postoperative course was uneventful with complete resolution of symptoms. To the authors' knowledge, this is the first report of an AOVM involving the intracranial portion of the accessory nerve. For any AOVM located within the cerebellomedullary cistern or one suspected of involving a cranial nerve, the authors recommend including immunohistochemistry with primary antibody to neurofilament in the histopathology workup.

Bilateral duplication of the abducens nerves: an incidental finding on magnetic resonance imaging

Although anomaly of the abducens nerve, including duplication, has been reported in anatomical papers, no radiological report exists regarding a duplicated abducens nerve observed on magnetic resonance (MR) imaging. We encountered a case of bilateral duplication of the abducens nerves, which was found incidentally on MR scans from an 11-year-old boy. He did not have any symptoms of eye movement related to abducens nerve abnormality; thus, the duplication was considered to be a normal variant in this patient. Radiologists should be aware that duplication of the abducens nerve may occur and can be diagnosed on MR, particularly when diagnosing symptomatic patients or as a preoperative assessment for microsurgery of the nerve.

Cavernous malformations isolated from cranial nerves: Unexpected diagnosis?

OBJECTIVES

Cranial nerves (CN) cavernous malformations (CMs) are lesions that are isolated from the CNs. The authors present three cases of CN CMs, for which MR was demonstrated to be critical for management, and surgical resection produced good outcomes for the patients. Surgical removal is the recommended course of action to restore or preserve neurological function and to eliminate the risk of future haemorrhage. However, the anatomical location and the complexity of nearby neural structures can make these lesions difficult to access and remove. In this study, the authors review the literature of reported cases of CN CMs to analyse the clinical and radiographic presentations, surgical approaches and neurological outcomes.

PATIENTS AND METHODS

A MEDLINE/Pub Med search was performed and revealed 86 cases of CN CMs. The authors report three additional cases in this study for a total of 89 cases. CMs affecting the optic nerve (CN II), oculomotor nerve (CN III), facial/vestibule-cochlear nerves (CN VII, CN VIII) have been described. The records of three patients were reviewed with respect to the lesion locations, symptoms, surgical approaches and therapeutic considerations. Clinical and radiological follow-up results are reported. Three patients (2 females, 1 male; age range 21-37 year) presented with three CN lesions. One lesion involved CN III, one lesion involved CN VII-CN VIII, and one involved CN II. The patient with the CN III lesion had a one-month history of mild right ptosis and diplopia. The patient with the CN VII-CN VIII lesion exhibited acute hearing loss and on the left and left facial paresis. The patient with the opticchiasmatic lesion presented with acute visual deterioration on the right and a left temporal field deficit in the left eye. Pterional and orbitozygomatic craniotomies were performed for the CN III lesion and the CN II lesion, and retrosigmoid craniotomy was performed for the cerebello-pontine angle lesion.

RESULTS

All patients experienced symptom improvement after surgery. On MR follow-up, recurrence was excluded in all patients.

CONCLUSIONS

CN CMs present with specific symptoms and require complex surgical techniques for resection. These lesions are frequently symptomatic, because of the complexity of the origin tissue. Symptomatic CN CMs should be resected microsurgically and completely when possible to prevent further losses of nerve function, improve function, avoid recurrence, and to eliminate the risk of future haemorrhages. The authors discuss the therapeutic options and the radiological features of these infrequent localisation of CMs. Specifically, the authors focus on the role of magnetic resonance imaging in the identification of these rare lesions.

A rare case of an extra-axial cavernous angioma in the cerebellopontine angle

Intracranial extra-axial cavernous angiomas are rare lesions. We report a rare case of extra-axial cavernous angioma in the cerebellopontine angle (CPA) in a 50-year-old male, who presented with lower cranial nerve palsy and gait ataxia. Computed tomography (CT) scan of the brain showed a hyperdense lesion in the left cerebellopontine angle. The lesion was totally excised by the retrosigmoid approach and a pathological examination confirmed the lesion to be a cavernous angioma. Following surgery, the lower cranial nerve palsy recovered significantly.

Cranial nerve cavernous malformations causing trigeminal neuralgia and chiasmal apoplexy: Report of 2 cases and review of the literature

BACKGROUND

Cavernous malformations (CMs) confined to the cranial nerves (CN) are extremely rare lesions.

CASE DESCRIPTION

The authors report 2 cases of CMs, one involving the trigeminal nerve presenting with a 3 years history of a refractory right trigeminal neuralgia that was microsurgically resected by a retromastoid approach with resolution of the neuralgia; and another CM involving the chiasma with an abrupt onset of vision loss with acute intralesional bleeding that was removed through a right pterional approach with vision improvement.

CONCLUSION

Surgical resection is recommended in the context of progressive significant neurological deficit, emergency decompression as a result of recent hemorrhage for symptomatic relief or increase in size on serial magnetic resonance imaging (MRI).