Evaluation of surgical treatment in 5 intracranial meningiomas

The purpose of this retrospective case series is to report the results of surgical treatment of five dogs (n=5) with intracranial meningiomas according to Shores and Brisson (1). Diagnosis was made by magnetic resonance imaging (MRI) and confirmed by histopathology. Cases were subdivided according to surgical approach into transfrontal (n=1; G1), parieto-occipital (n=2; G2) and rostrum-tentorial (n=2; G3). Neurological status was assessed immediately after surgery (T0), at 8 days (T8), and at 30 days (T30). Neurological status was re-evaluated thereafter only if neurological signs occurred. In all subjects, the outer cortex was removed with a high--speed spherical burr (5 mm) until the inner cortex was exposed. Once the thinnest point of the internal cortex was identified, the remaining plate of bone was removed using a Kerrison rongeur, taking care not to perforate the underlying dura mater. The portion of the dura mater above the neoplasm was then removed with a bipolar electrocauteriser for neurosurgery. An operating microscope was used to distinguish the neoplastic tissue from the healthy brain parenchyma and to identify the cleavage plane of the meningioma. Intracranial surgery tampons (Saugermed, Medikokim, Istanbul, Turkey) were inserted into the cleavage plane to allow retraction of the cerebral tissue from the neoplastic tissue. Tumour resection was performed centrifugally or centripetally, depending on the case, using arthroscopic forceps or bipolar electrocautery. Excision of the neoplasm was performed using arthroscopic forceps and a neurosurgical aspirator calibrated to -0.40 bar. In the subject who underwent transfrontal craniotomy (G1), the bone flap was fixed with polydioxanone (PDO) sutures. The duration of surgery (time from first incision to skin suture) was 88 minutes in G1, an average of 74 minutes in G2 and 112 minutes in G3. No dog showed neurological changes at T8 and T30. No dog showed MRI changes at T30. Two subjects had convulsive crises 4 (G1) and 2 (G3) months after surgery requiring follow-up MRI. One of these (G3) showed signs of tumour recurrence and died 14 days later. Survival times were 125 days for G1, an average of 977 days for G2 and 491.5 days for G3. The use of an operating microscope allowed better spatial resolution. The use of surgical swabs allowed for retraction of brain tissue and optimal delineation of the tumour cleavage plane. In addition, the swabs provided effective haemostasis, thus reducing the operative time. Handling meningiomas is complex due to their structure and the fragile consistency of the neoplastic tissue. The safe performance of traction manoeuvres is essential to prevent iatrogenic dissemination of neoplastic cells, but it prolongs operative time. The use of a low-pressure aspirator and bipolar electrocautery allowed a firmer yet delicate grip of the meningioma, reducing iatrogenic dissemination of neoplastic cells. Finally, the use of PDO sutures instead of cerclage sutures avoided metallic artefacts in the control MRIs of the patient treated with the transfrontal approach (G1). Although the number of cases is limited, the advantages of the surgical technique reported in this case series are similar to those previously reported (1). Further research is needed in surgical management of intracranial meningiomas to reduce complication rates and operative times.