[Management of bone-invasive en-plaque petrosal meningiomas. Removal using tailored petrosectomy]

The invasion of bone responsible for hyperostosis is a typical phenomenon associated with en-plaque meningiomas. Although the sphenoid wing and spheno-orbital region are most frequently affected, petrosal involvement is rare and its surgical treatment difficult. Hyperostosis is caused by bone invasion, is responsible for the clinical signs, and prompts the surgeon to use an à la carte drilling that has to be evaluated preoperatively and carried out depending on tumor extension and the treatment goals.

We report two cases of invasive and evolving en-plaque petrosal meningiomas. Hyperostosis, bony modifications, and intracranial portion of the lesion were responsible for cophosis, facial palsy, trigeminal neuralgia, dysphonia, and laryngeal palsy in one case, and were responsible for hearing loss and facial palsy in the other case.

In both cases, the à la carte petrosectomy allowed us to achieve total removal of the lesion. In one case, we used a trans- and infralabyrinthine transjugular approach (to control the extension of the lesion in the jugular foramen, within the sinusojugular axis, and in the internal auditory canal), associated with an anterior petrosectomy (to control the invaded petrous apex, Meckel's cave, and a middle cranial fossa extension). In the other case, we used a retro- and infralabyrinthine transsigmoid transtentorial approach to control the venous axis, the posterior fossa dura, and the tentorium. Total removal of the tumor including bone invasion was achieved in both cases. Neurological deficits improved or remain unchanged. Transient postoperative facial palsy recovered in two months.

An à la carte petrosectomy performed by a surgical team with great expertise in the field of petrous bone anatomy and segmentation should lead to total removal including exposure of the dural tail and intracranial portion of the tumor, while preserving all cranial nerve functions.