Journal of Neuro-Oncology 54: 277–286, 2001. © 2001 Kluwer Academic Publishers. Printed in the Netherlands.
Neuroendoscopic anatomy and surgery in pineal region tumors Role of neuroendoscopic procedure in the ‘minimally-invasive preferential’ management Shizuo Oi, Masami Kamio, Tatsuhiro Joki and Toshiaki Abe Department of Neurosurgery, The Jikei University, School of Medicine, Tokyo, Japan
Key words: pineal region tumors, minimally-invasive preferential management, neuroendoscopic anatomy, neuroendoscopic surgery Summary The therapeutic modalities for pineal region tumors in Western countries differ from those in far-eastern countries, that is, Japan and Korea, mainly because of the different patient populations. The majority of pineal region tumors in Japan and Korea are radio sensitive and/or chemosensitive, and adjuvant therapy rather than extensive surgery plays the main part in the treatment of these tumors. The authors have applied minimally-invasive preferential management in pineal region tumors in last 8 years. For the therapeutic regimen, if the tumor markers alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) were not detected in serum and there was significant ventricular dilation visualized on neuroimages, neuroendoscopic surgery was first applied for tumor debulking with tissue diagnosis and gross morphological analysis of the tumor and the intraventricular structures, followed by third-ventriculostomy. In the results, our minimally-invasive preferential regimen clarified the precise indication for neuroendoscopic procedures, and the majority of our patients with dilated ventricles and no evidence of tumor markers were treated satisfactorily with effective neuroendoscopic procedures as the initial procedure. Then avoided unnecessary craniotomy and radiotherapy and promised excellent therapeutic outcomes. Neuroendoscopic procedures have a great advantage in the management of chemo- or radiosensitive tumors, such as germinoma, pineoblastoma, or primitive neuroectodermal tumor. The neuroendoscopic anatomy including the lateral and third ventricles with a pineal region tumor with or without tumor dissemination was described in detail, together with the neuroendoscopic surgical technique.
Introduction There are more than 17 different pathological tumor types in the pineal region [1], and the therapeutic approach differs for each [1–5]. The conventional radical operative procedure may be important for the initial treatment. However, a majority of the tumor types require adjuvant therapy. Even when a large proportion of the original tumor is surgically removed, disseminated/metastasized masses can have an adverse effect on the therapeutic modality. Recently, minimally-invasive procedures, including neuroendoscopic surgery, stereotactic surgical procedures, stereotactic radiotherapy or radiosurgery, and so on, have been widely accepted as neurosurgical treatment strategies.
It is the purpose of this review article to summarize the neuroendoscopic anatomy and surgical procedures in minimally-invasive preferential management for pineal region tumors.
Historical trend in management of pineal region tumors Until the late 1970s even in North America, there was a tendency to select radiation therapy as the initial procedure in the treatment of pineal region tumors before attempting radical resection [6,7]. However, along with the recent advances in microneurosurgical technique and instrumentation, it has become generally accepted in North America and Europe that in
278 the management of pineal region tumors the histological diagnosis should be obtained before radiotherapy and/or chemotherapy [1,2,8]. The evidence in support of this tactic includes the following [1,2,8]: 36–50% of pineal tumors are either benign or radioresistant; there is increasing evidence that even low doses of radiation may be harmful to the developing brain; advances in diagnostic and surgical techniques have significantly lowered the mortality and morbidity rates associated with surgery in the pineal region; and histological diagnosis permits the rational development of histologyspecific therapy. We performed a worldwide survey of the management of pineal region tumors, along with an analysis of racial differences in tumor distribution in 1991 [4] and again in 1997 [5]. It was clearly demonstrated that the therapeutic regimen for pineal region tumors has been changing during recent years, even in North America and Europe. In 1991, we therefore performed the first worldwide survey of the management of pineal region tumors [4], in order to gather information regarding the collective experience in and treatment regimens for pineal region tumors in different patient populations. The results demonstrated again that there were significant racial differences in the epidemiology. The therapeutic modalities also differed with the different patient populations. Germinoma is the most common type, accounting for more the 80% of pineal region tumors occurring in patients between 15 and 35 years of age in the Japanese population [4]. This tumor is extremely radiosensitive and curable only by radiotherapy. Its epidemiological characteristics are now known to be identical to those in the Korean population as well [5]. The worldwide survey repeated in 1997 indicated that the low-dose radiation test or radiotherapy is still recommended as the initial treatment step in management of pineal region tumors by a number of Japanese and Korean [5] neurosurgeons. Germinomas and gliomas are similarly common tumor types in North America and Europe. This is the major reason why radical surgery with tissue diagnosis is performed in these countries, as opposed to the regimen performed in Japan and Korea [1,4,5]. In 2000, the authors summarized our experiences with cases treated with minimally-invasive preferential management in a prospective study. For the therapeutic regimen, if the tumor markers alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) were not detected in the serum and there was significant ventricular dilation visualized on neuroimages, neuroendoscopic surgery was first applied for tumor
debulking with tissue diagnosis and gross morphological analysis of the tumor and the intraventricular structures, followed by third ventriculostomy. We managed a total of 20 patients prospectively with this regimen, and concluded that our minimally-invasive preferential regimen clarified the precise indication for neuroendoscopic procedures. Therefore, the majority of our patients with dilated ventricles and no evidence of tumor markers were treated satisfactorily with effective neuroendoscopic procedures as the initial procedure, avoiding unnecessary craniotomy and radiotherapy and promising excellent therapeutic outcomes. Neuroendoscopic procedures The authors prefer ‘multi-axial approach’ to the pineal region and floor of the third ventricle (Figure 1) at present time. The neuroendoscopic instrumentation included a rigid-rod endoscope (Oi-Samii system; Karl Storz, Germany, and/or Gaab system; Codman, Boston, MA, USA) for morphological analyses and Oi-Samii system; Karl Storz, Germany, and/or a steerable/flexible-rod endoscope (Codman) for the surgical maneuver [9]. Two burr holes were made in the right frontal region on the pupillary line, one at the coronal suture and the other behind the hair line. Ventricular taps were made by using a manometric ventricular trocar [10] (by Oi et al., 1988) directed toward
Figure 1. Neuroendoscopic ‘Multi-axial approach’ to the pineal region tumor (T) (Oi S et al., 2000) [l3].
279 the right foramen of Monro from each burr hole, and the intraventricular pressure was measured and a cerebrospinal fluid (CSF) sample was obtained. The trocar was replaced by a No. 14 French peel-away sheath (Cook, Inc., Bloomington, IN, USA) and inserted in both tracks. A rigid-rod endoscope is first inserted into the right lower frontal burr hole and moved into the lateral ventricle to observe the gross morphological characteristics of the ventricle. Then the endoscope is introduced into the third ventricle and the gross appearance of the tumor under and over the massa intermedia (thalamic adhesion) is analyzed. Next, Oi-Samii system; Karl Storz, Germany, and/or a steerable flexiblerod-fiber endoscope is used to perform debulking of the tumor and a sufficient number of tumor specimens is obtained from the various parts of the tumor. Using the other burr hole made at the coronal suture, the same procedure for gross morphological analysis with the aid of the rigid-rod endoscope is repeated. Then the steerable flexible endoscope is used to perform third ventriculostomy in the usual fashion. The EVD tube was kept in place for postoperative continuous intracranial pressure (ICP) monitoring during the next few days in cases in which there was no tumor dissemination. If there was any evidence of tumor dissemination, the EVD tube was kept in place for a course of chemotherapy with continuous CSF drainage. Neuroendoscopic anatomy The neuroendoscopic anatomy obtained in each approach is described in Figures 2– 9, where T: Tumor, T(S): Tumor specimen, TD: Tumors Dissemination, Fnx: Fornix, FM: Foramen of Monro, CP: Choroid Plexus, IR: Infundibular Recess, MB: Mamillary Body (Rt.: right, Lt.: left), Aq: Aqueduct of Sylvius, III Vstm: Third Ventriculostomy, III: Third Ventricle, MI: Massa Intermedia, SPR: Suprapineal Recess. First, the rigidrod endoscope was introduced to determine the intraventricular structure and gross appearance of the tumor. From the frontal burr hole through the foramen of Monro, the pineal region occupied by tumor was under direct vision, which focused under (Figure 7) or over (Figure 8) the massa intermedia. The floor of the third ventricle was observed via the coronal approach by using the bilateral mamillary bodies and the infundibular recess as landmarks (Figure 2). Multiple rigid-rod endoscopes with different view angles (0◦ , 30◦ , 70◦ and 120◦ ) were used to observe anterior horn, body,
and triangle of the right lateral ventricle (Figure 2) and the entire third ventricle, especially to detect the gross appearance of tumor dissemination (Figures 2 and 4). Instrumentation and techniques of neuroendoscopic surgery The instrumentation in neuroendoscopic surgery has rapidly improved along with the most recent developments in the application of specific neuroendoscopic techniques. There are various aspects that should influence the choice of neuroendoscope for clinical use. Table 1 (Oi S, 1996) summarizes these aspects, along with realistic indications based on the authors’ experience. The most salient advantage of the rigid-rod neuroendoscope is its high image quality, leading to fine morphological analysis with much brighter illumination than its counterparts. On the other hand, the most important advantage of the steerable–flexible neuroendoscope is its mobility in the ventricle or any other confined space, such as the cystic cavity of the brain parenchyma. The advantages of the semi-rigid-rod neuroendoscope include its fine structure, offering angulation in operative maneuvers, and its possible application as a stylet for shunt placement. The limitations of each type of neuroendoscope must also be understood. The fixed operative field and larger instrument size for the rigid-rod, and the dimmer operative field and limited choice of instrument size for the semi-rigid-rod and flexible/steerable-rod types, are considerable disadvantages. These advantages and disadvantages should be taken into account in the planning of individual procedures [ll]. Now, we have developed a new model of rigid-rod neuroendoscope with a new concept of ‘Frameless Rigidrod Neuroendoscope’, namely Oi-Samii Handi Pro (Karl Storz, Germany). In our recent clinical experience with application of this new model of neuroendoscope, it was thought that the pineal region tumors could be well dealt with this new instrumentation. In dealing with pineal region tumors neuroendoscopically, a steerable/flexible-rod endoscope as in our early experience and Oi-Samii Handi Pro as the freehand frameless rigid-rod endoscope in the recent cases was used for the therapeutic procedures. The tumor was debulked and a satisfactory amount of tissue was obtained from various parts of the tumor. During this procedure, constant irrigation was performed using artificial CSF (Otsuka, Tokushima, Japan) or Haltman
280
Figure 2. Neuroendoscopic anatomy of pineal region tumors via coronal high-frontal burr hole with a 0-degree-angle rigid scope (the lateral ventricle). (See Figure 1.)
Figure 3. Neuroendoscopic anatomy of pineal region tumors via coronal high-frontal burr hole with a 0-degree-angle rigid scope (the third ventricle). (See Figure 1.)
solution, which passed through an EVD tube guided from the other trajectory as well as through the working channel of the endoscope to keep the operative field clear and to control the bleeding. Tumor removal was essentially performed using biopsy microforceps
measuring 3 mm when opened. If the endoscopic and MR examination of the ventricles confirmed no tumor dissemination, third ventriculostomy was performed in the standard fashion [12]. The neuroendoscopic finding is more reliable to detect the ‘radiologically-negative’
281
Figure 4. Neuroendoscopic anatomy of pineal region tumors via coronal high-frontal burr hole with a 30-degree-angle rigid scope (pineal region tumor at orifice of the aqueduct). (See Figure 1.)
Figure 5. Neuroendoscopic anatomy of pineal region tumors, third ventriculostomy via coronal high-frontal burr hole with a 30-degreeangle rigid scope (after third ventriculostomy and tumor biopsy). (See Figure 1.)
tumor dissemination in the ventricle (Figure 2) and/or the subarachnoid space. The center of a triangle formed by the infundibular recess and bilateral mamillary bodies was penetrated with a microforceps, and the hole
was dilated using a No. 2 French catheter balloon (Medi-tech, Watertown, MA, USA), which could be inflated up to 4 mm. Communication between the third ventricle and the basal cistern was then confirmed, and
282
Figure 6. Neuroendoscopic anatomy of pineal region tumors, third ventriculostomy via coronal high-frontal burr hole with a 0-degreeangle rigid scope (after third ventriculostomy). (See Figure 1.)
Figure 7. Neuroendoscopic anatomy of pineal region tumors via low-frontal burr hole with a 0-degree-angle rigid scope (pineal region tumor below the massa intermedia). (See Figure 1.)
283
Figure 8. Neuroendoscopic anatomy of pineal region tumors via low-frontal burr hole with a steerable–flexible fiberscope (pineal region tumor over the massa intermedia). (See Figure 1.)
the morphological characteristics of the cistern were again examined with the aid of the rigid-rod endoscope to rule out tumor dissemination.
Minimally-invasive preferential management of pineal region tumors In 2000, the authors proposed ‘Minimally-invasive preferential management of pineal region tumors’ [13]. The regimen is as follows (Table 2): If the tumor markers (AFP and HCG) were undetected in serum and ventriculomegaly was found on computerized tomography (CT) or magnetic resonance (MR) imaging, neuroendoscopic surgery was first applied for tumor debulking and tissue diagnosis, with
gross morphological analyses of the tumor and intraventricular and intracisternal structures. Information on the gross appearance of the tumor and presence of tumor dissemination was obtained, following which endoscopic third ventriculostomy was performed in the standard fashion [12,14]. An EVD tube was inserted at the same time. Neuroendoscopic surgery was not performed in patients with small ventricles; in these patients stereotactic surgery was applied. If serum proved to be positive for tumor marker(s), extensive surgery was first attempted for radical total removal of tumor, as long as there was no evidence of tumor dissemination. In patients in this group in whom there was tumor dissemination, immediate adjuvant chemotherapy was selected as the initial procedure and was followed by whole neuroaxis radiation therapy (WNRT). An EVD system was used for postoperative
284
Figure 9. Neuroendoscopic anatomy of pineal region tumors via low-frontal burr hole with a 30-degree-angle rigid rod scope (neuroendoscopic tumor debulking of a pineal region tumor). (See Figure 1.)
Table 1. Instrumentation in neuroendoscopic surgery and salient advantage of various types of neuroendoscope (Oi S, 1996) [11] Type of neuroendoscope
Advantages
Disadvantages
Realistic indications
Rigid-rod
High-resolution image Brighter operative field Various instruments Application to stereotactic procedures Finest rod Small angulation in operative maneuvers Stylet manipulation Mobility with wide operative field Multiangulation in operative maneuvers
Fixed operative field Instruments larger and more invasive
Tumor resection or biopsy Ventriculostomy in larger inlet of the ventricle
Less bright operative field Limited instruments
Shunt placement Ventriculostomy in thin ventricular wall
Less bright operative field Limited size of instruments
Ventriculostomy Ventricular septum fenestration Tumor biopsy
Semi-rigid-rod
Flexible/steerable-rod
285 Table 1. Minimally-invasive preferential management of pineal region tumors (Oi S et al., 2000) [13] Specific items* Initial procedure
Hydrocephalus
Tumor markers** [AFP/HCG]
Multiplicity Radiological dissemination*** specificity****
+
–
±
±
Neuroendoscopic surgery
–
–
–
+ (1)
Stereotactic biopsy
±
+
+
±
Whole-CNS radiation Tx
±
–
±
+ (2)(3)
Chemotherapy
±
+
–
±
Radical surgery
–
–
–
+ (4)
Follow up
Second-step procedure
Specific regimen in individual tumor type
= determinative preference * + = yes; – = no; ± = either yes or no; ** Tumor markers (serum/CSF); AFP = alpha-fetoprotein; HCG = human chorionic gonadotropin *** On MRI **** + (1) = lateral extension; + (2) = calcified firm mass; + (3) = AV shunt; + (4) = small cystic mass
management of all patients with ventriculomegaly who had undergone third ventriculostomy or craniotomy. A daily CSF specimen was obtained for cytological analysis. The EVD system was kept open even in patients in whom there was no intraoperative evidence of tumor dissemination. After confirmation of cytological findings negative for tumor tissue in CSF for several days after the procedure, continuous ICP monitoring was performed to check the patency of the third ventriculostomy or the reopened aqueduct. If the CSF cytological analysis proved positive postoperatively, the EVD system continued to be used as long as possible, along with chemotherapy, in all patients treated with any surgical procedure. Subsequent procedures are determined on the basis of verified individual tumors. For treatment of germinomas and pineoblastoma; if no tumor dissemination was confirmed by pre-, intra-, or postoperative findings, stereotactic radiotherapy or radiosurgery was performed after one course of chemotherapy with ICE regimen (isofomid, cisplatin and etoposide) and followed by 2 additional courses of chemotherapy. For treatment of malignant germ-cell tumors (MGC), after extensive surgery, adjuvant chemotherapy with the ICE regimen is performed in 3 courses in all cases. Then radiation therapy is started using vari-
ous methods, depending on the evidence of tumor dissemination. For treatment of teratomatous (TRT) and neuroectodermal tumors (NET) other than pineoblastomas (PB), extensive surgical removal is performed. As for adjuvant therapy, if the tumor was a low-grade glioma or if the patient was younger than 5 years of age, postoperative treatment did not include radiotherapy. If the tumor was a malignant TRT or highgrade glioma, conventional focal radiotherapy was performed, followed by chemotherapy with ICE for one year. Neuroendoscopic procedures have a great advantage in the management of chemo- or radiosensitive tumors, such as germinoma, pineoblastoma or primitive neuroectodermal tumor (PNET). However, the second step of the regimen is still challenging in cases of malignant germ cell tumors, malignant gliomas, and other chemo- or radioresistant tumors. Although the patient populations of Japan and Korea are more suitable for minimally-invasive preferential management, tumor management in the different patient population with a higher incidence of chemo- and radioresistant tumors remains a major ongoing subject of research in the development of a therapeutic regimen, especially for pineal region tumors in populations of North America and Europe.
286 References 1. Edwards MSB, Hudgins RJ, Wilson CB, Levin VA, Wara WM: Pineal region tumors in children. J Neurosurg 68: 689–697, 1988 2. Allen JC, Nisselbaum J, Epstein F, Rosen G, Schwartz MK: Alphafetoprotein and human chorionic gonadotropin determination in cerebrospinal fluid. An aid to the diagnosis and management of intracranial germ-cell tumors. J Neurosurg 51: 368–374, 1979 3. Anonymous: A statistical study of brain tumors in Japan: general features. The Committee of the Brain Tumor Registry of Japan. Jpn J Clin Oncol 17: 19–28, 1987 4. Oi S, Matsumoto S: Controversy pertaining to therapeutic modalities for tumors of the pineal region: A worldwide survey of different patient populations. Childs Nerv Syst 8: 332–336, 1992 5. Oi S, Matsuzawa K, Choi JU, Kim Ds, Kang JK, Cho BK: Identical characteristics of the patient populations with pineal region tumors in Japan and in Korea and therapeutic modalities. Childs Nerv Syst 14: 36–40, 1998 6. Allen JC: Management of primary intracranial germ cell tumors of childhood. Pediatr Neurosci 13: 152–157, 1987 7. Poppen IL, Marino R Jr: Pinealomas and tumors of the posterior portion of the third ventricle. J Neurosurg 28: 357–364, 1968
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