Relationship between the degree of pyramidal tracts invasion and postoperative outcome in patients with insular glioma

Objective To explore the clinical study of the extent of pyramidal tract invasion and the postoperative outcome of insular gliomas. Methods The clinical data of 41 patients with insular glioma undergoing surgical treatment from July 2010 to July 2019 at Department of Neurosurgery, the First Affiliated Hospital of University of Science and Technology of China (Anhui Provincial Hospital) were retrospectively analyzed. Patients were classified into 3 types according to the degree of invasion of pyramidal tracts. The tumor invading only the anterior lower part of the insular lobe was categorized as type Ⅰ, that invading posterior upper part of the insular lobe as type Ⅱ, and that with invasion and destruction of the inner capsule structure as type Ⅲ. The differences of limb motor dysfunction before and after operation, pathological types and postoperative outcome among patients with different types were analyzed. Results Among the 41 patients, 18 were type Ⅰ (43.9%), 20 were type Ⅱ (48.8%), and 3 were type Ⅲ (7.3%). No type Ⅰ patients had motor impairment before or after surgery. Four patients with type Ⅱ tumor had motor dysfunction before surgery, of whom 3 reported improvement after surgery and 1 developed further worsened symptoms. One type Ⅱ patient had new motor dysfunction after surgery. Type Ⅲ patients had motor dysfunction before operation, and their symptoms worsened after operation. There were 11 cases, 5 cases, and 1 case of total resection of type Ⅰ, type Ⅱ, and type Ⅲ tumors, respectively. Compared with the rate of total resection in type Ⅰ patients, that in type Ⅱ+ Ⅲ patients was significantly lower[26.1% (6/23) vs. 11/18, P=0.026]. There were 3 cases, 7 cases, and 3 cases of World Health Organization (WHO) grade Ⅲ-Ⅳ glioma in patients of type Ⅰ, Ⅱ and Ⅲ, respectively. The difference was statistically significant (P=0.015). A total of 29 cases were followed up for 3-72 months (22.7±12.0 months). Thirteen patients with type Ⅰ were followed up, and none of them recurred. Fifteen patients with type Ⅱ were followed up, 7 of whom relapsed. One patient with type Ⅲ was followed up, and the residual tumor increased and the patient died in the third month after operation. Kaplan-Meier survival analysis revealed significant difference in the survival rate among the patients of 3 types (P<0.01). Conclusion The heavier the pyramidal tacts is invaded, the higher the pathological grade of insular glioma, the lower the total surgical resection rate, and the worse the postoperative outcome. Key words: Glioma; Pyramidal tracts; Treatment outcome; Insula; Typing