Cavernous malformations isolated from cranial nerves: Unexpected diagnosis?

•CMs should be considered in the differential diagnosis of extra-axial space-occupying lesions along the courses of the cranial nerves.•Their clinical characteristics should prompt a high level of preoperative suspicion due to bleeding.•The radiological characteristics of these lesions are suggestive but often non-diagnostic particularly when small lesions without evident haemorrhages are present.•The risk of progression to CN dysfunction and the tendency for recurrence following subtotal excision are the reasons that radical surgery represents the standard recommended treatment for CN CMs.

ObjectivesCranial 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 methodsA 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.ResultsAll patients experienced symptom improvement after surgery. On MR follow-up, recurrence was excluded in all patients.ConclusionsCN 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.