see also Tentorial meningioma.
Falcotentorial meningiomas are rare tumors of the pineal region that arise from the dural folds where the falx and tentorium meet and are often intimately related to the vein of Galen and straight sinus.
Among pineal lesions meningiomas are extremely rare and include falcotentorial meningioma and velum interpositum meningiomas. It is very difficult to discriminate between these two lesions and description of the clinical presentation and the surgical technique in approaching these tumors is limited.
Meningiomas arising from the falcotentorial junction are extremely rare. Fewer than 50 cases have been reported in the literature.
Because the tumor arises at the junction of dural folds in which the straight sinus and both torcular and arachnoid granulations are found, however, its infrequency in that region is not surprising.
Most patients present with symptoms of increased ICP and occasionally with visual symptoms related to the tumor’s occipital location.
Computerized tomography (CT) showed no specific findings, but there was no evidence of edema around the tumor. Magnetic resonance (MR) imaging revealed a round, smooth-bordered mass with a peritumoral rim, without edema, and showing marked contrast enhancement. The multiplanar capability of MR imaging delineated the relationship between the tumor and adjacent structures better than did CT. Detailed knowledge of the vascular structures, especially evidence of occlusion of the galenic venous system and the development of collateral venous channels, is critical for successful surgery; stereoscopic cerebral angiography is necessary to achieve this aim.
Because these tumors grow slowly, collateral venous outflow channels for the deep venous system develop via the basal vein of Rosenthal, the petrosal, the precentral cerebellar, and the pontomedullary veins. Preoperative cerebral angiography is crucial to determine the status of the straight sinus because the lower falx cerebri, lateral tentorium, and upper falx cerebelli are excised with the tumor.
Because bilateral occipital retraction is required during the operation, transient cortical blindness routinely develops in cases involving largersized tumors. Patients should be informed of this transient neurological deficit prior to surgery.
Clinical data in a consecutive series of 13 patients treated for a meningioma of the FT junction were retrospectively reviewed. Tumors were classified into 4 types according to their dural origin and tumor extent as depicted from preoperative MRI.
Main presenting symptom in 9 women and 4 men (mean age, 56 years) was headache (69%) and gait disturbance (54%). Clinical examination revealed gait ataxia in 62% of the patients. The tumor displaced the vein of Galen inferiorly in 6 patients, superiorly in 2, and medially in 5 cases. The main surgical approach to the meningioma was via an occipital interhemispheric route (10 patients). Additional resection of the falx and/or incision of the tentorium was performed in 6 cases each. A complete resection (Simpson grade 1 and 2) was achieved in 85% of patients. Permanent surgical morbidity was 23%. One tumor recurrence in an atypical meningioma was observed after the mean follow-up period of 6.2 years (range, 1-14 years) with clinical and MRI examination and had to be reoperated. Eighty-five percent of the patients regained full daily activity on follow-up.
The surgical approach should be tailored to the dural origin and extent of the tumor as depicted from preoperative MRI. Preservation of the straight sinus and Galenic venous system is recommended 2).
Between 1975 and 1996, in the Neurosurgical Unit at the University of Rome, “La Sapienza,” 13 consecutive patients underwent surgery for falcotentorial meningiomas that had been localized on preoperative imaging and confirmed by histology. The surgical approach varied according to the site of the tumor.
Nine meningiomas were totally removed and 4 subtotally. Three patients (23.0%), all treated early in the series, died after the operation. Ten patients (76.9%) survived: 3 (23.0%) had postoperative neurologic complications necessitating reintervention, and 7 patients (53.8%) had an uneventful postoperative course. Two of the 4 patients who had subtotal resections had regrowth at 1 year that responded to radiosurgery.
The ideal surgical approach to falcotentorial meningiomas should allow gross total removal and minimum brain retraction while safeguarding the galenic system and other vital neighboring structures. Toward achieving this aim we propose detailed preoperative imaging studies to classify falcotentorial meningiomas according to their site and direction of growth-craniocaudal or anteroposterior-in relation to the cerebellar tentorium 3).
Two types of neglect are described: hemispatial and motivational neglect syndromes. Neglect syndrome is a neurophysiologic condition characterized by a malfunction in one hemisphere of the brain, resulting in contralateral hemispatial neglect in the absence of sensory loss and the right parietal lobe lesion being the most common anatomical site leading to it. In motivational neglect, the less emotional input is considered from the neglected side where anterior cingulate cortex harbors the most frequent lesions. Nevertheless, there are reports of injuries in the corpus callosum (CC) causing hemispatial neglect syndrome, particularly located in the splenium. It is essential for a neurosurgeon to recognize this clinical syndrome as it can be either a primary manifestation of neurosurgical pathology (tumor, vascular lesion) or as a postoperative iatrogenic clinical finding. The authors report a postoperative hemispatial neglect syndrome after a falcotentorial meningioma removal that recovered 10 months after surgery and performs a clinical, anatomical, and histological review centered in CC as key agent in neglect syndrome 4).