Is “en-bloc” excision, an option for select large vascular meningiomas?
A 25-year-old male presented to our hospital in drowsy state with history of headache for 3 years progressively worsening for 6 months. His Glasgow Coma Scale was 13/15, magnetic resonance imaging (MRI) brain revealed giant left lateral sphenoid wing meningioma measuring 8 × 7 × 5 cm3 with no encasement of major blood vessels []. Preoperative embolization was not feasible. Hence left external carotid artery (ECA) was exposed in the neck and kept occluded. Large fronto-temporal scalp flap was raised after adequate infiltration of local anesthetic with adrenaline, and use of Raney's clips. Large fronto-temporal free bone flap was raised with craniotome and temporal bone rongeured flush with middle cranial fossa. Profuse bleeding of bone edges was controlled with bone wax. Bipolar coagulation of middle meningeal artery and other vessels over the dura was carried out. Dura was opened just around the tumor, and reflected as a flap detaching it from the underlying tumor. The tumor surface was studded with blood vessels. Bipolar coagulation was performed all around the exposed tumor surface thereby devascularizing and shrinking the tumor. Gradually the tumor started to separate from the arachnoid plane and started to bulge in a pulsatile manner []. Progressively deeper circumferential dissection carried out with placement of patties protecting the adjacent arachnoid layer. It appeared as if the brain pulsations were gently pushing the tumor out of the dural defect. No retractor or tumor manipulation was used throughout the procedure and finally, the whole tumor was delivered en bloc []. The blood loss was around 500 ml, most of which occurred during craniotomy. Patch duraplasty was carried out using pericranium, and layered closure performed. Postoperatively the patient had improved remarkably, contrast enhanced computed tomography (CECT) showing no residual tumor, and was discharged in good functional status on fourth day []. This ‘en bloc’ technique, as elaborated below, has been utilized in a series of seven more large meningiomas (>5 cm) safely with less blood loss.\nPatients with meningioma were positioned intraoperatively so that tumor was more superficial than brain. Sufficiently large basal craniotomy was carried out. Meningiomas with suspected encasement of neurovascular structures and significant interposition of brain around the tumor attachment were considered for internal decompression before dissection of tumor capsule. However, meningiomas with no contraindication as above were taken up for surgery with the rule of 4 D's: Devascularization, Diminutive dural opening, Detachment, and either Debulking followed by dissection or Dissection without debulking. After extensive coagulation of dural surface vessels, dural opening was made just at the tumor margin, so that surrounding brain was not exposed. The decision on performing internal decompression was made following early severance of dural attachment. Whenever arachnoid plane appeared favorable, dissection was carried out without debulking, and nearly always the tumor was pushed gradually by the underlying brain pulsations and edema so that the tumor gets delivered en bloc. The main advantages of ‘en bloc’ removal appear to be lesser bleeding and shorter operative time. The limited dural opening cannot be overemphasized to avoid herniation of the edematous brain being pushed out by the tumor. Also if tumor cannot be freed of its attachment in the initial phase of surgery internal debulking becomes unavoidable.\nOf the total 35 large meningiomas (>5 cm) operated by us in 2 years, 8 patients had en bloc removal while the rest had initial debulking. The mean blood loss in en bloc removal was around 400 ml, with no patient having new neurological deficit, new onset seizures, or postoperative hematomas.