The Classification Of Craniopharyngioma And Its Application In Surgical Treatment Of Craniopharyngioma

PartⅠThe classification of craniopharyngioma and it's surgical applicationPurpose: To observe the course of suprascllar arachnoid mater and pia mater, and the construction of all meninges near of pacchionian foramen in foetus brain, and to suppose the possible originated sites of craniopharyngioma. To summary the imaging features, intraoperative course of 121 patients operated on for craniopharyngiomas with different size, component,and locations, a distinct classification of craniopharyngiomas was advocated. The originated site, clinical and surgical characteristic in each group of patients were discussed.Methods: The course of suprasellar arachnoid mater and pia mater, and the construction of all meninges near of pacchionian foramen was observed under microscopy. The clinical data of 121 patients who underwent primary microsurgery for craniopharyngiomas at our institute was analysed retrospectively. A topographic classification of the tumor was applied based on their relationships with the sellar diaphragm, the stalk and the floor of the third ventricle (3rdVF) . The proposed mechanism for the formation of a craniopharyngioma was also discussed according to the morphological study of the foetus brain.Results: Observation of pia mater near of pacchionian foramen in foetus brain showing that at the margin of pacchionian foramen, diaphragma is tightly adherence to the surface of hypophysis, suggesting that diaphragma plays a important role in the growth pattern of craniopharyngioma: tumors of type A originates from the subdiaphragmatic area, the growth of this type of tumor will elevate and stretch the diaphragm sellae, building up subdiaphragmatic pressure to elevate the optic apparatus and large vessels upward ,obstructive hydrocephalus is rare even in very huge tumor. However, tumors of supradiaphragmatic origin will grow without diaphragmatic covering and directly contact surrounding structures. Among them, tumor of type B1 mainly growth into prechiasmatic space without invading into the third ventricle while type B2 which is thought to be originated from the anterior infundibular part of the wall of the third ventricle always growth at retrochiasmatic space, the thin capsule of the cystic tumor grows along the plane of lowest resistance, the third ventricle, and accordingly causes obstructive hydrocephalus. From January 1999 to december 2005, 181 patients with a craniopharyngioma were treated with microsurgery in our department. Of these 181 patients, 60 patients had undergone previous surgical exploration at other clinics or in our department, these 60 cases were excluded from analysis to eliminate the influence conducted by previous surgical procedure to the relationships between the tumor capsule and surrounding structures, thus cases of 121 patients who underwent primary microsurgery were available for final review. There were 52 female and 69 male whose ages at the time of surgery ranged from 11-month to 72 years(51 patients were≤15 years old). A classification of the tumors into 3 topographical groups(subdiaphragmatic, suprasellar extraventricular, and intra-extraventricular accordingly) were performed according to preoperative MRI findings, which was coincident to intraoperative impression in each group of patients in 100%, 80%, 94.5% respectively. 19 cases with their tumor classified as subdiaphragmatic on pre-operative MR scan were invariably verified by the surgeon's impression during operation or by reviewing the videotapes from these cases. As for the primarily supradiaphragmatic craniopharyngiomas, the real tumor-3rdVF relationships in some cases were erroneously depicted on pre-operative MR scan. Each group of patients has definite features in respecting to clinical presentations, approach selections and resectabilities. Tumors of type A and type B1 can always be resected by an extra-axial route while tumors of type B2 through both transcerebral(trans-lamina terminalis, transcallosal, or transcortical transventricular) and extra-axial routes, and is more difficulty to accomplish total removal.Conclusion: The growth pattern of craniopharyngiomas are interpreted into three topographical groups based on the pre-operative MR scan and intraoperative impression: subdiaphragmatic, suprasellar extraventricular, and intra-extraventricular. Tumor's radiological features on preoperative MRI enable us to determine the growth pattern of tumors and its relationships with diaphragmatic and 3rdVF especially in subdiaphragmatic group. Preoperative determination of the tumor's growth pattern can help us to select the proper surgical approach allowing exposure of the tumor while avoiding the hypothalamic structures. PartⅡThe growth pattern of primary subdiaphragmatic craniopharyngiomas and its surgical treatmentPurpose: To discuss the growth pattern of primary subdiaphragmatic craniopharyngiomas, and to explore the radiological feature and intraoperative course of subdiaphragmatic craniopharyngiomas. Methods: The radiological, operative, and pathological findings of 19 patients who underwent primary microsurgery for subdiaphragmatic craniopharyngiomas at our institute were reviewed. The suprasellar capsules of tumors in 6 cases were pathologically examined to determine whether the surface was covered with the dural membrane.Results: There were 12 boys and 7 girls whose age at the time of diagnosis were under 14 years old except for one 16-year old girl. The mian clinical presentation includes deterioration of vision in 19 patients, 12 complained about diabetes insipidus, 10 patients with headache, 8 patients with growth retardation. Preoperative MRI studies usually demonstrated primarily intrasellar and suprasellar masses with its solid portion at the base and a huge rounded and symmetrical cystic suprasellar extension, The tumors measured between 40 and 120 mm in maximum diameter(mean tumor diameter, 51mm±4.7). All 19 patients had a intrasellar components of tumor with a enlargement of the pituitary fossa, in two of them, the tumors also involve the infrasellar space. The direction of tumor's suprasellar expantion was always toward prechiasmatic space, the tumor displaced the optic chiasm and the horizontal portions of the anterior cerebral artery and the anterior communicating artery upwards, while the third ventricle, excluding the anterior basal part, remained unoccupied, obstructive hydrocephalus is rare even in very huge tumor. Calcification were found in all cases. During operation, it was noted continuation of the tumor surface with the dura mater of the skull base, and direct abutment of the tumor to the sellar walls or the pituitary gland was also found in some cases. The stalks can identified connected at the top of the tumor capsule when tumors were relatively small. One patient died during post-operative period, the remaining 18 patients follow-up periods ranged from 1 to 106 months (33±19 months, mean±SD). Three deaths occurred during the follow-up period. Two of them were huge tumor involving infrasellar space with maximum diameter on MRI 10cm and 12cm. The third patient, an 10- year-old girl who had recurrence of her tumor 12months after the initial operation, didn't receive any further therapy because of financial problems and died 4 years postsurgery. The follow up review for other 15 survivors shows 9 patients in good and 5 in moderate condition.Conclusion: We noticed that huge intra-suprasellar craniopharyngiomas rarely occurred in adult. Our subsequent clinical analyses revealed that intra-suprasellar craniopharyngiomas significantly differed from the primarily supradiaphragmatic craniopharyngiomas with respecting to patient age, tumor size, tumor location, symptoms, tumor-stalk relationships, surgical approach, respectability, and outcome. We, therefore, propose that these infradiaphramatic craniopharyngiomas represent a topographical entity different from supradiaphragmatic craniopharyngiomas.