Mario Ammirati

Olfactory Groove Meningiomas

Olfactory groove meningiomas originate from the crista galli and adjacent lamina cribrosa near the junction between the cribriform plate and the planum sphenoidale [3]. In terms of clinical presentation and size of the tumor at the time of diagnosis little can be added to Cushing’s description. These tumors are still usually diagnosed when they are of a significant size, and the most common presenting symptoms are altered mental status followed by decreased vision [14]. Although anosmia and Foster-Kennedy syndrome (primary optic atrophy on the side of the lesion and contralateral papilledema) [10] are often mentioned as typical symptoms of olfactory groove meningiomas [1,11], they are only rarely observed [6]. Anosmia was probably the presenting complaint in only three of the 29 patients reported by Cushing [3] and in none of Bakay’s patients [2]. Foster-Kennedy syndrome was seen in only seven of Cushing’s patients [3], and this is not surprising considering that olfactory groove meningiomas are usually bilateral.

Solitary brain metastasis 13 years after removal of renal adenocarcinoma.

SummaryWe report a case of a patient who developed a single brain metastasis to the cerebellum 13 years after removal of a renal adenocarcinoma. The cerebellar metastasis was removed twice due to local recurrence one year after the first operation. The patient is alive and doing well 18 months after the second neurosurgical procedure. The metastasis was not associated with any other evidence of disease. Brain metastasis may present many years after removal of kidney adenocarcinoma and when not associated with other evidence of disease their operative treatment may carry a good prognosis.

Medial Sphenoid Wing Meningiomas

Cushing was the first to systematize sphenoid wing meningiomas, dividing them into those arising from the inner third (deep, medial, or clinoidal third meningiomas), middle third (alar meningiomas), and outer third (pterional meningiomas) [3]. This distinction is still useful and practical today, not only because the respective symptoms differ, but also because the surgical problems, strategies, and goals vary greatly from one region to another. Clinoidal sphenoidal wing meningiomas grow mainly into the middle fossa and parasellar region. They may displace but usually surround the middle cerebral artery, supracavernous internal carotid artery, and optic nerve; the cavernous sinus may be compressed or invaded by these tumors. In large tumors the frontal and temporal, lobes are compressed from below and are separated by the tumor. The symptoms associated with this type of tumor growth consist mainly of visual disturbances in the form of decreased vision homolaterally and visual field defect due to compression of the lateral chiasm and proximal optic tract; seizures may also occur [2].

Jugular Foramen Meningiomas

Jugular foramen meningiomas are extremely rare; Cushing did not mention any such isolated case [1], and there are only a few reports of meningiomas involving primarily the jugular foramen [1, 4, 7].

Meningiomas Involving the Lower Clivus and the Foramen Magnum (Craniospinal Meningiomas)

Cushing divided the meningiomas involving the craniocervical junction into craniospinal and spi-nocranial, depending on whether the tumor was reaching the foramen magnum from above or from below. Related to this he recognized a significant surgical difference in that the craniospinal tumors were located in the cisterns anterior to the brainstem pushing the cervicomedullary junction poste-rolaterally while the reverse was true in spinocranial tumors [1]. According to Cushing, Hallopeau in 1872 was the first to describe a meningioma arising from the lower clivus and extending into the foramen magnum (autoptic report) [1]. Cushing himself described the case of a patient who underwent a negative cervicothoracic laminectomy with the suspicion of syringomyelia or cord glioma; autopsy disclosed a meningioma originating from the lower clivus and extending into the foramen magnum [1].

Posterior Pyramid Meningiomas (Cerebellopontine Angle Meningiomas)

The cerebellopontine angle is the space between the cerebellum and the pons; from a surgical stand point, it corresponds to the cerebellopontine angle cistern. It is bounded posteriorly by the flocculus and the adjacent petrosal surface of the cerebellum at the junction of the superior and inferior limbs of the cerebellopontine fissure with the anterior most aspect of the horizontal fissure (petrosal fissure). These areas of the cerebellum are situated in a posterior plane with respect to the flocculus and are represented medially by the simple lobule superiorly and by the biventral lobule inferiorly, and laterally by the most anterior aspect of the superior and inferior semilunar lobules, respectively, superiorly and inferiorly [11]. Anteriorly, the medial aspect of the posterior surface of the pyramid and the lateral aspect of the clivus at the level of the petro-occipi-tal synchondrosis delimit and at the same time continue this space into the prepontine space medially and into the posterior part of the lateral incisural space rostrally [10].

Meningiomas Involving the Cavernous Sinus

Surgery of the cavernous sinus has received great impetus in the past few years [3, 9], and its indica tions are still being defined [9]. Dolenc et al. [3] have reported 63 patients who underwent neoplastic intracavernous surgery, 40 of whom for meningiomas, with an overall mortality rate of 6%, permanent cranial nerve (II-VI) morbidity of 22%, and a total tumor removal of 71% and 73% of the patients returning to their premorbid activity. Sekhar et al. [9] were able totally to remove 13 of 17 (76%) intracavernous meningiomas, and in 42 patients undergoing intracavernous operations for neoplasms there was no mortality; extraocular muscle function was worse in 12%, better in 42%, and unchanged in 69%, and most of the patients had a good performance score postoperatively. Kawase et al. [5] reported on total removal of 5/7 intracavernous meningiomas, with two patients experiencing permanent cranial nerve worsening. The majority of meningiomas reported by Dolenc et al. [3], Sekhar et al. [9] and Kawase et al. [5] were invading the cavernous sinus from surrounding areas. Lesoin et al. [7], reporting on 16 patients with purely intracavernous meningiomas stated that total removal of intracavernous meningiomas is not possible without permanently jeopardizing cranial nerve function. It is evident that removal of intracavernous meningiomas is more dangerous than removal of intracavernous neurinomas or chondromas [7, 9].

Meningiomas in Miscellaneous Locations

We have had nine patients with tumors in miscella neous locations: two coming from the lateral floor of the middle fossa; one in the temporal squama, middle and inner ear extending en plaque in-tradurally; one in the anteromedial frontal basis going into the sphenoid and frontal sinus; one in the petrous pyramid and cerebellopontine angle; one in ventricle IV and cerebellopontine angle; one en plaque in the anterior, middle, and posterior fossa; one involving the anterior and middle skull base bilaterally and the posterior fossa on one side; and one in the petrous pyramid, temporo-occipital bone, and cerebellopontine angle. The last of these is described in detail below (“Illustrative Case”). Table 17.1 details our material.

Upper and Middle Clivus Meningiomas

Under the heading of upper and middle clivus meningiomas we include those operated upon when the tumor is located exclusively or mainly in corre spondence of the upper and middle clivus. Only a few tumors fall into this group, and these represent the initial stage of tumors that with further growth would become petroclival, craniospinal, or incis-ural meningiomas. This view is supported by combined clinical and surgical observations showing that in many patients with petroclival, craniospinal, or incisural meningiomas the original symptoms were related to abducens paresis, often preceding by many years other symptoms and falsely diagnosed as strabism; moreover at surgery, in the same group of patients, many times the tumor attachment is found to be in proximity to the dural entrance or the intradural clival course of nerve VI, at the level of the middle-upper clivus. The reason why a counterpart does not exist in tumors originating from the lower clivus is the anatomical lack of a nervous structure which, like the abducens nerve, may be compressed by a still relatively small dural mass, resulting in a focal neurological deficit. The fact that these tumors are small at the time of surgery does not mean that their surgical removal is easier than that of larger meningiomas of this area (see “Surgical Considerations”).

Middle Third Sphenoid Wing Meningiomas

These tumors usually show an expansive type of growth and may be completely removed via a fron-totemporal approach, using the same technique as described in Chap. 5. Due to the fact that these tumors do not usually involve the optic apparatus or internal carotid artery, their surgical removal is easier than that of medially located tumors [1].