Parasagittal meningioma surgery

The radical resection of parasagittal meningiomas without complications and recurrences is the goal of the neurosurgeon. Nowadays, different managements are proposed ¹⁾.

Surgical removal of falcine meningioma and parasagittal meningiomas, particularly during a unilateral approach, requires adequate exposure of the midline to avoid undue retraction of the medial ipsilateral cerebral hemisphere. Key technical considerations include avoidance of injury to the superior sagittal sinus (SSS) and management of frontal sinus transgression when approaching very anterior extra-axial masses.

Frequently warrants an increased exposure of the sagittal sinus and the falx cerebri to facilitate more relaxed retraction of the frontal lobe and improve the safety and manipulation of the tumor resection. Achieving this exposure necessitates craniotomy and frontal bone removal over the SSS; Rutkowski et al. call it a “two-part parasagittal craniotomy” to help with the safe dissection of the midline dura crossing the SSS to the opposite side with diploic bone channel drilling to create a thin lip of the inner table that can be removed piecemeal for safe dissection of the dura crossing the midline in a two-part parasagittal craniotomy. This technique may be utilized in a safe, consistent, and efficacious manner to avoid injury to the superior sagittal sinus when access around the same is warranted, for instance, in cases of falcine and parasagittal tumors. ²⁾.

Yu et al showed the Gravity-Assisted Ipsilateral Paramedian Approach for Parafalcine Meningioma Resection was safe and advantageous because it does not result in contralateral brain impingement and does not require brain retraction ³⁾.

Preserving the venous outflow is the key point, but this may preclude radical resection. Different surgical strategies have been proposed.

Once tumor is exposed a partial internal debulking is performed. Then the point of attachment is peeled away using bipolar cautery to divide feeding vessels. Then the main portion of the tumor may be separated from the brain, with the tumor being avascular once the vascular pedicle has been transected.

Ricci et al. considered the preservation of the cortical veins to be important, and, when possible, they recommended the reconstruction of the anterior third of the superior sagittal sinus (SSS). There experience has led them to believe that until now surgery is a winning choice if practiced by expert hands ⁴⁾.

To contribute to the debate on the optimal strategy for treating these tumors, a single-institutional, single-surgeon series of patients with parasagittal meningiomas was analyzed and the available literature reviewed. Analysis of the data obtained in the 67 patients confirmed good outcome and long-term tumor control following a surgical strategy aimed to preserve venous outflow. These findings and the results of the authors' analysis of the literature emphasize that the goal of radical tumor resection should be balanced by an awareness of the increased surgical risk attendant on aggressive management of the SSS and bridging veins ⁵⁾.

In surgical planning of the parasagittal meningioma, invasion and occlusion of the superior sagittal sinus are important factors. When tumor is located within anterior 1/3, or when angiographic finding shows total occlusion of superior sagittal sinus, it is regarded that the ligation of superior sagittal sinus is safe. A case of parasagittal meningioma in 59-year-old male patient with complete occlusion of superior sagittal sinus which was confirmed by preoperative angiography, who developed temporary neurologic deterioration after superior sagittal sinus ligation and resection ⁶⁾

Indocyanine green videoangiography (ICGVA) can assist the different stages of parasagittal meningiomas surgery, guiding the vein management and tumor resection strategies with a favorable final clinical outcome. However, Della Puppa et al., experience that the use of other complementary tools was mandatory in selected cases to preserve functional areas. Further studies are needed to confirm that the application of ICGVA in parasagittal meningioma surgery may improve the morbidity rate, as reported ⁷⁾.

For treating a patient with multiple falcine and parasagittal lesions, Yamaguchi et al. believe that it is beneficial to resect the maximum possible number of lesions during one operation, even if some lesions are asymptomatic. This practice can potentially reduce the total number of operations during a patient's lifetime ⁸⁾.

Spektor et al. describe the purely endoscopic removal of an atypical parasagittal meningioma in a patient who could not undergo standard craniotomy due to severe scalp atrophy following childhood irradiation for tinea capitis.

A 68-year-old man in good general health presented with a parasagittal meningioma that recurred following subtotal removal and adjuvant fractionated stereotactic radiosurgery (FSR). The scalp above the tumor location was very diseased and precluded a regular craniotomy for tumor removal. A 4-cm craniotomy was made in the midline forehead, where the skin was normal. A rigid endoscope was advanced under neuronavigation through the interhemispheric fissure, which provided good access with limited retraction, until the tumor was encountered at a depth of 7-8 cm. Two surgeons performed the surgery using a “four-hands technique”. The tumor was removed and the insertion area was resected and coagulated.

The surgery was uneventful, with no coagulation or transection of major veins. A subtotal resection was achieved, and the patient recovered with no neurological deficit.

Safe resection of parasagittal meningiomas with a purely endoscopic technique is feasible. This option needs further exploration as an alternative strategy in patients with severely atrophic scalp skin that greatly increases the risk of significant healing complications with calvarian craniotomy ⁹⁾.

This technique, which consists of the insertion of a Venflon tube in the vein during anastomosis, results in easier handling and proper apposition of the vein, resulting in an improved quality of the anastomosis. The technique was successfully applied in a patient after parasagittal meningioma resection, and the patency of the cortical vein was confirmed postoperatively on magnetic resonance venography ¹⁰⁾.

It has been reported a combination of endovascular stent placement and radiotherapy ¹¹⁾.

After radiosurgery peritumoral edema tends to occur in meningiomas with a parasagittal position. Radiation necrosis, infiltration of inflammatory cells, and radiation injury to the vasculature causing hyalinization of blood vessels are suggested as the underlying histopathology ¹²⁾.