Falcotentorial meningiomas

Introduction

Meningiomas that arise along the tentorium account for 3% to 6% of intracranial meningiomas. Because the tentorium is a large dural fold that separates the supra- and infratentorial spaces, tumors can occur in a variety of places. Yasargil classified tentorial meningiomas into medial incisural, falcotentorial, paramedian, peritorcular, and lateral tentorial lesions. Falcotentorial meningiomas are generally those tumors that occupy the area where the falx attaches to the tentorium with involvement of the straight sinus; however, some also include those tumors along the posteromedial tentorial incisura. In this chapter, we present a case of a patient with a falcotentorial meningioma.

Example case

Chief complaint: headaches and lethargy

History of present illness

A 44-year-old, right-handed woman with no significant past medical history who presented with increasing headaches and lethargy. Over the past 2 to 3 weeks, she complained of worsening headaches and increasing fatigue. This had interfered with her work. She denied any nausea or vomiting, double vision, or focal weakness ( Fig. 55.1 ).

Medications : None.
Allergies: No known drug allergies.
Past medical and surgical history: None.
Family history: No history of intracranial malignancies.
Social history: Baker, no smoking or alcohol.
Physical examination: Awake, alert, oriented to person, place, and time; Cranial nerves II to XII intact; No drift, moves all extremities with full strength.

	Sébastien Froelich, MD, Pierre-Olivier Champagne, MD, PhD, Neurosurgery Hospital, Lariboisiere, Paris, France	Javier Avendano Mendez-Padilla, MD, National Institute of Neurology and Neurosurgery, Tlalpan, Mexico	Laligam N. Sekhar, MD, Isaac J. Abecassis, MD, University of Washington, Seattle, WA, United States	Harry Van Loveren, MD, University of South Florida, Tampa, FL, United States
Preoperative
Additional tests requested	CT MRI with CISS/FIESTA MRV CT angiogram	Cerebral angiogram/venogram	Cerebral angiogram/venogram with possible embolization	Cerebral angiogram
Surgical approach selected	Right occipital transtentorial craniotomy	Right parieto-occipital craniotomy	Right frontal EVD, bilateral occipital and suboccipital craniotomy	Bilateral occipital/suboccipital craniotomy, supra- and infratentorial approach with EVD
Anatomic corridor	Occipital transtentorial	Posterior interhemispheric	Occipital transtentorial with possible supracerebellar infratentorial	Supracerebellar infratentorial
Goal of surgery	Simpson grade II or III	Simpson I resection, preserve vascularity	Simpson grade II or III because of possible straight sinus invasion	Simpson grade I pending venous occlusion by tumor
Perioperative
Positioning	Prone with 5- to 10-degree left rotation	Semi-sitting	Semiprone, right-side down	Prone
Surgical equipment	Surgical navigation Surgical microscope with ICG Doppler Ultrasonic aspirator	IOM (SSEP, cranial nerves)Surgical navigationSurgical microscopeUltrasonic aspirator	EVD Surgical navigation IOM (SSEP, MEP, BAERs) Surgical microscope Ultrasonic aspirator Endoscope Retractor system	EVD Surgical navigation IOM (SSEP/MEP) Surgical microscope Ultrasonic aspirator
Medications	Steroids Antiepileptics	Steroids Mannitol	Steroids Antiepileptics Mannitol	Steroids Antiepileptics Mannitol
Anatomic considerations	Straight sinus, cortical draining veins, tentorium, internal cerebral veins, vein of Galen, vein of Rosenthal, splenium, third ventricle, pineal gland, tectum, PCA, trochlear nerve	Venous sinuses, inferior longitudinal sinus, vein of Galen, brainstem injury	Venous sinuses, deep draining veins cortical veins on occipital lobe, brainstem	Brainstem, deep central veins (Galen, straight sinus, ICV, Rosenthal)
Complications feared with approach chosen	Venous infarct	Superior sagittal sinus injury, venous injury or infarction, intratumoral hemorrhage	Venous injury, cortical retraction injury of visual cortex	Retraction injury, venous injury, brainstem injury, inability to resect tumor
Intraoperative
Anesthesia	General	General	General	General
Skin incision	Right paramedian linear	Right linear perpendicular to sagittal sinus	Inverted U-shaped over occipital and suboccipital regions	Linear from above inion to C2 spinous process
Bone opening	Right occipital	Right parieto-occipital	Bilateral occipital/suboccipital	Bilateral occipital/suboccipital
Brain exposure	Right occipital lobe	Right parietal lobe, interhemispheric fissure	Bilateral occipital and cerebellar hemispheres	Bilateral occipital and cerebellar hemispheres
Method of resection	Linear incision 1 cm right parasagittal, cruciate incision in pericranium, retraction of skin using pericranium to avoid self-retaining retractors, two burr holes on the SSS and one on the transverse sinus using cutting and diamond burrs, drill over torcula if needed, occipital craniotomy encompassing sinuses, shave midline border of craniotomy, preparation for EVD is needed using surgical navigation, dural opening 1 cm away and parallel to the SSS and transverse sinus with counter incision toward torcula, evaluate venous flow with Doppler, expose falx and tentorium, EVD if necessary to avoid brain retraction, identify straight sinus using observation/navigation/Doppler, incise tentorium 1 cm away from sinus, coagulate dural margin to enlarge dural opening, debulk tumor with ultrasonic aspirator, peel away arachnoid from tumor after sufficient debulking, venous preservation leaving tumor remnant if needed, watertight dural closure, remove EVD, tack up sutures	Lumbar drain linear incision crossing sagittal sinus burr holes across sinus, craniotomy that exposes sagittal sinus, dura opened based on sagittal sinus, drain CSF from EVD, occipital lobe minimally retracted to expose interhemispheric fissure, retract falx upward, divide small bridging veins from occipital lobe to falx, identify and preserve deep basal veins, devascualrize tumor as much as possible, centrally debulk tumor with ultrasonic aspirator, mobilize tumor, remove supratentorial component, if necessary divide falcotentorial dura and tentorium 1 cm parallel to straight sinus watching for fourth cranial nerve, resect infratentorial compoent, watertight dural closure, EVD for at least 1 day	Right frontal EVD, inverted U-shaped incision, burr holes straddling sagittal sinus (4)/right lateral (2), 3 piece craniotomy (right occipital up to sinus, left occipital after dissecting SSS, suboccipital craniotomy down through foramen magnum), open suboccipital dura, drain cisterna magna, L-shaped dural opening in right occipital area, dural opening in supracerebellar area avoiding large veins, expose tumor by right parasagittal approach, divide tentorium lateral to straight sinus, expose tumor by supracerebellar approach if needed, debulk tumor and dissect from surrounding structures, maintain arachnoid plane over brainstem and only dissect after sufficient tumor debulked, leave tumor if adherent to vein of Galen/anterior tentorial notch/straight sinus, protect deep veins, confirm resection with endoscope, watertight dural closure with graft as needed, dural tack up sutures	Right frontal EVD placed in supine position, positioned prone, occipital craniotomy with exposure of torcula/transverse/sagittal sinuses, suboccipital dura opened and reflected toward torcula, tumor exposed and debulked, capsule mobilized, tentorium circumferential cut to allow supratentorial exposure and debulked, if necessary can open supratentorial dura toward sagittal sinus, retract occipital lobes laterally and access tumor between hemispheres
Complication avoidance	Possible EVD, expose sagittal and transverse sinuses, minimal occipital lobe retraction, open tentorium adjacent to straight sinus, debulk tumor prior to manipulating arachnoid, leave tumor remnant to preserve veins	Lumbar drain, expose sagittal and transverse sinuses, minimal occipital lobe retraction, identification of basal veins, divide falx and tentorium to access contralateral and infratentorial components, watertight dural closure	EVD, multiple craniotomies to protect sinus, drain CSF early, maintain arachnoid plane over brainstem, protect deep draining veins, use of endoscope to inspect cavity	EVD first, bilateral occipital/suboccipital craniotomy, removal of tentorium to allow supratentorial access, possible occipital interhemispheric if debulking not adequate
Postoperative
Admission	ICU	ICU	ICU	ICU
Postoperative complications feared	Venous thrombosis or infarct, diplopia, hemianopsia	Venous infarct, brainstem lesion, hydrocephalus	Venous infarct, occipital cortical injury, brainstem injury, injury to deep draining veins, hydrocephalus, seizures	Brainstem injury, venous infarct, CSF leak, hydrocephalus
Follow-up testing	CT within 12 hours after surgery MRI/MRV within 48 hours after surgery	CT immediately after surgery and 1 day after surgeryMRI within 72 hours after surgery	CT immediately after surgery MRI prior to discharge EVD 1 day after surgery	CT same day after surgery MRI within 24 hours after surgery
Follow-up visits	2 months after surgery	2 weeks and 1 month after surgery	2 and 6 weeks after surgery	10 days after surgery 6 weeks after surgery
Adjuvant therapies recommended for WHO grade	Grade I–observation Grade II–radiation if growth Grade III–radiation	Grade I–observation Grade II–radiation if residual Grade III–radiation if residual	Grade I–observation vs. radiation depending on age Grade II–fractionated radiation or proton beam therapy Grade III–fractionated radiation or proton beam therapy	Grade I–observation Grade II–radiation if residual Grade III–radiation