Outcomes and Surgical Approaches for Pineal Region Tumors in Adults: A Retrospective Study of a Single-Center Over 12 Years

Abstract

Background Pineal region tumors are considered rare, deeply located, and very difficult to resect. They can cause various symptoms by compressing and obstructing different structures. Contradictory data have been reported regarding various aspects of surgical outcomes in different patient positioning.

Objectives This retrospective study aimed to describe the variety of pineal region tumors and patient positioning in pineal region surgeries and compare the neurological outcomes during different approaches.

Materials and Methods From January 1, 2010, to December 31, 2022, 61 patients with pineal area tumors were hospitalized at the National Center for Neurosurgery. Thirty-five patients' histology examinations were available. Twenty-nine patients had open surgical excision. Regarding approaches, supracerebellar infratentorial, posterior transfalcine interhemispheric, and occipital transtentorial approaches were employed.

Results Among 35 patients, 17 had hydrocephalus and required ventricular drainage to address third ventricle obstruction. Complete tumor resection was achieved in 55% of patients. The mortality rate was 13.7% in the open surgical group and 15.625% in the endoscopic third ventriculostomy (ETV) group.

Conclusion Proper patient positioning and selecting the optimal approach are crucial for a successful outcome.

Keywords

pineal region tumor - supracerebellar approach - occipital transtentorial approach - pineal biopsy - germ cell tumor - oncology

Introduction

The pineal gland is located on the posterior wall of the third ventricle, above the quadrigeminal lamina. It consists of three types of cells: pineal parenchyma cells, glial cells, and connective tissue cells. This gland regulates hormones and controls visual function during puberty and the sleep–wake cycle.[1] More specifically, the gland projects inferiorly and posteriorly into the quadrigeminal cistern, and its anatomic boundaries include the thalamus on either side, the superior splenium of the corpus callosum, and the backside of the third ventricle wall.[2] The pineal gland can be linked to multiple neurosurgical issues, such as pineal cysts, different tumor types, and vascular abnormalities,[3] potentially leading to impairment of pineal gland function and destructive damage on adjacent functional structures. Subsequently, surgical intervention there is often deemed risky due to the gland's location, surrounded by vascular and neurological structures, situated at the geometric center of the cranial cavity.[4]

Pineal region (PR) tumors are found less commonly in adults, accounting for only 1%, compared with 3 to 11% of pediatric patients.[5] According to the WHO classification, PR tumors are divided into three categories: pineal parenchymal tumors (PPTs), germ cell tumors (GCTs), and tumors originating from nearby anatomical tissues,[6] with germinoma being the most common type among all pineal tumors in Europe, the United States, and Japan, accounting for up to 50% of patients.[5] Hydrocephalus commonly emerges as one of the complications associated with PR tumors.[7] Those tumors compress nearby structures, including the aqueduct, and consequently result in obstructive hydrocephalus, characterized by a disruption in the formation, flow, or absorption of cerebrospinal fluid (CSF).[8]

Patient positioning is crucial in surgical planning, with selection influenced by factors such as the planned surgical approach, tumor location, and its relationship with adjacent structures. Furthermore, ensuring correct patient positioning is essential for enhancing intraoperative visibility, minimizing the risk of mechanical trauma and retraction ischemia, and preventing substantial brain edema.[9] [10] [11]

Most importantly, not only is there no universally agreed protocol for evaluating and treating pineal area tumors[12] but also diverse data are reported regarding various aspects of surgical outcomes in different patient positioning.[13] [14] These conflicting findings pertain to neurological and functional outcomes, the success rate of surgical interventions, overall survival, and mortality rates. Therefore, our study aimed to describe the initial experience of a single center in patient selection, positioning, and approach in PR tumors.

Materials and Methods

The Patient Population and Study Design

The data were obtained from archives of the National Center for Neurosurgery in Kazakhstan from January 2010 to December 2022. We enrolled patients who satisfied the following criteria: aged ≥18 years and diagnosed with a PR tumor. The patients who underwent only endoscopic third ventriculostomy (ETV) were excluded from the data. Among the cohort of 61 patients, histological examination was conducted in only 35 cases, with surgical tumor removal performed in 29 of these patients.

The following data were collected from the medical records: age, sex, clinical symptoms, the need for hydrocephalus treatment before the surgery, tumor size and type, status upon discharge, location of the tumor, the extent of the surgery, type of dural origin, consistency of the tumor, adjuvant treatment, and follow-up care. The extent of resection was categorized based on the postoperative magnetic resonance imaging (MRI), either as gross total resection or subtotal resection. The follow-up and survival were based on the date of the surgery to the last clinical follow-up or death.

Surgical Approaches

The surgical approaches are delineated and explained in [Fig. 1]. The selection of the approach was based on the orientation of the major axis of the tumor. The supracerebellar infratentorial approach (SCITA) was indicated when the tumor was located below the vein of Galen complex and did not extend into the cerebellomesencephalic fissure or beyond the tentorial edges. For lesions extending toward the fourth ventricle and/or demonstrating lateral extension, the occipital transtentorial approach (OTA) was utilized. The interhemispheric transcallosal transchoroidal approach was employed for tumors extending horizontally into the third ventricle, traversing the interthalamic adhesion up to the level of the foramen of Monro, and extending into the mesencephalic cerebellar cistern and the fourth ventricle.

Fig. 1 Selection of surgical approaches to pineal region tumors. (A) Posterior transcallosal interhemispheric approach for meningiomas with a falcotentorial matrix, (B) transoccipital approach for a big mass in the supratentorial area, and (C) supracerebellar infratentorial approach if the veins are from above, for a mass compromising the cerebellum, extending to the tectum, or extending to the rear side of the third ventricle.

Patient Positioning

Patients were placed in a modified lateral decubitus position resembling a park bench, typically favoring the left side for the supracerebellar transtentorial approach, which was intended for a right-handed neurosurgeon. This positioning, previously described as “reverse transsphenoidal” by Little et al,[15] involved aligning the patient three-quarters laterally, with the anteroposterior plane extending from the chin to a finger's breadth away from the sternum. The patient's rotation was adjusted 45 degrees away from the lesion's side, tilting the nose downward toward the floor and laterally flexing 30 degrees toward the floor. To prevent pressure neuropathies, a soft pillow was positioned under the armpit. Additionally, a soft bandage secured the ipsilateral shoulder, ensuring it remained free from interference with the surgeons' movements. We minimized excessive head and neck movements that could obstruct venous drainage from the head. In our practice, lumbar drainage was not employed before surgery. The three-quarters lateral position provided gravitational retraction on the nondominant occipital lobe, offering advantageous surgical conditions, as shown in [Fig. 2].

Fig. 2 Modified lateral decubitus position (park bench). (A) After induction of anesthesia, the patient was turned to the left side, and pillows were placed under the armpit and iliac crest. A soft pillow was also placed between the knees. Then, we performed hand positioning with the help of a multi-axis surgical arm positioner. The skull clamp was positioned on this stage. The bed was elevated to 30 degrees to increase brain relaxation. (B) The bandage on the upper shoulder was used to retract the shoulder to the back. After shoulder retraction, we performed pelvic fixation with the belt. (C) The top view. (D) The view from the front.

Statistical Analysis

Data were collected in an Excel spreadsheet, and then statistical analysis was performed using the Stata/MP-18.0 (StataCorp, College Station, Texas, United States) software, which involved plotting Kaplan–Meier survival curves to assess overall survival.

Results

Population Characteristics

The age range of participants spanned from 18 to 65 years, with the highest frequency observed in the 45- to 59-year age group. The mean age was 45 years, with females comprising approximately 57% of the cohort and males approximately 43%. Clinical presentation varied depending on tumor size and its impact on CSF flow. Among 29 patients, 17 had hydrocephalus and required ventricular drainage to address third ventricle obstruction. Overall, 58 of the patients required shunt placement. Symptom-wise, the majority of patients (80%) reported persistent headaches, while over 54% experienced vision disturbances and diplopia was observed in 49%. Additionally, less commonly reported symptoms included nausea and vertigo, gait instability (17%), memory impairment (14%), insomnia (14%), and hearing impairment (11%).

Pathological Findings

Among the 35 patients with PR tumors who underwent histological examination, 27 patients initially underwent ETV, out of which only 9 returned for subsequent open surgical resection during the follow-up period. Additionally, nine patients had a biopsy performed as a preliminary measure before undergoing open neurosurgical procedures. Moreover, 13 patients solely received ventriculoperitoneal shunt placement. In the open neurosurgical group, a total of 29 patients underwent neurosurgical procedures. The distribution of patients' sex and age according to histological tumor type is shown in [Table 1]. In all, 18.75% were PPTs, 12.50% were GCTs, and 68.75% were tumors from anatomical tissues (TATs).

Table 1 Patient characteristics with the presenting symptoms, follow-up data, and operation details

	Gender	Age (y)	Presenting symptoms	Follow-up (mo)	Histological examination	WHO grade	Preoperational ventricular preparation	Approach	Patient positioning	Extent of resection
1	M	29	Headache, vertigo	Died 6 mo later	Anaplastic ependymoma	3	Ventriculoperitoneal shunt placement	Posterior transcallosal interhemispheric	Park bench	Subtotal
2	M	18	Headache, diplopia, vision loss, N&V	103	Immature teratoma	3	Arendt placement	Supracerebellar infratentorial	Sitting	Subtotal
3	F	25	Headache, vision loss, N&V, memory loss, change of handwriting	101	Anaplastic oligoastrocytoma	3	Arendt placement	Supracerebellar infratentorial	Sitting	Subtotal
4	M	27	Headache, diplopia, vision loss, N&V	Died 36 mo later	Germinoma	–	Arendt placement	Supracerebellar infratentorial	Sitting	Subtotal
5	M	35	Headache, vertigo, N&V, seizure	98	Lymphoid tissue tumor	–	Ventriculoperitoneal shunt placement	Supracerebellar infratentorial	Sitting	Subtotal
6	F	64	Vertigo, sleep deprivation, headache accompanied by a darkening in front of the eyes when tilting the head back	Died 2 mo later (in hospital)	Pineoblastoma	4	Ventriculoperitoneal shunt placement	Supracerebellar infratentorial	Sitting	Subtotal
7	F	45	Headache, vertigo	95	Pinealoma	1	ETV + Arendt placement	Posterior transcallosal interhemispheric	Semi-sitting	Total
8	F	25	Headache, vertigo, gait unsteadiness	90	Pineal parenchymal tumor of intermediate differentiation	3	–	Occipital transtentorial	Prone	Subtotal
9	F	55	Headache, diplopia, vision loss, N&V	84	Psammomatous meningioma	1	ETV	Supracerebellar infratentorial	Prone	Total
10	F	64	Headache, diplopia, N&V	84	Pineoblastoma	4	–	Supracerebellar infratentorial	Park bench	Total
11	F	51	Headache, diplopia, vision loss	72	Hemangioblastoma	1	–	Occipital transtentorial	Prone	Total
12	F	47	Headache, diplopia, vision loss, N&V	70	Psammomatous meningioma	1	–	Occipital transtentorial	Prone	Total
13	M	45	Headache, vision loss, N&V, sleep deprivation	68	Pinealoma	1	Arendt placement	Posterior transcallosal interhemispheric	Park bench	Total
14	M	20	Headache, vertigo, gait unsteadiness, seizure	62	Germinoma		ETV	Supracerebellar infratentorial	Prone	Total
15	F	28	Diplopia, hearing loss, vertigo, gait unsteadiness, loss of sensation in the left extremities	60	Psammomatous meningioma	1	–	Posterior transcallosal interhemispheric	Prone	Subtotal
16	F	58	Diplopia	58	Psammomatous meningioma	1	–	Supracerebellar infratentorial	Prone	Total
17	F	37	Hearing loss	55	Pinealoma	1	–	Supracerebellar infratentorial	Sitting	Total
18	F	33	Headache, memory loss	50	Transitional meningioma	1	–	Posterior transcallosal interhemispheric	Park bench	Total
19	F	36	Headache, diplopia, vision loss, vertigo	45	Diffuse astrocytoma	2	Ventriculoperitoneal shunt placement	Occipital transtentorial	Park bench	Subtotal
20	M	24	Headache, vertigo, gait unsteadiness, seizure	40	Pineoblastoma	4	ETV + ventriculoperitoneal shunt placement	Occipital transtentorial	Park bench	Subtotal
21	F	42	Diplopia, hearing loss, vertigo, gait unsteadiness, loss of sensation in the left extremities	36	Cavernous malformation	–	Ventriculoperitoneal shunt placement	Supracerebellar infratentorial	Park bench	Total
22	F	30	Diplopia	Died 15 mo later	Diffuse astrocytoma	2	–	Posterior transcallosal interhemispheric	Supine	Subtotal
23	F	44	Hearing loss, confusion, loss of orientation	20	Solitary fibrous tumor/hemangiopericytoma	2	Arendt placement	Supracerebellar infratentorial	Park bench	Total
24	M	57	Headache, memory loss	20	Transitional meningioma	1	–	Supracerebellar infratentorial	Park bench	Total
25	M	55	Headache, diplopia, vision loss, vertigo	Died 18 mo later	Pineoblastoma	4	Arendt placement	Supracerebellar infratentorial	Prone	Subtotal
26	M	65	Headache, diplopia, vision loss	6	Pineal parenchymal tumor of intermediate differentiation	3	ETV	Supracerebellar infratentorial	Park bench	Total
27	F	26	Headache, diplopia, vision loss, N&V	6	Pinealoma	1	Ventriculoperitoneal shunt placement	Supracerebellar infratentorial	Park bench	Total
28	M	39	Headache, vision loss, N&V, sleep deprivation	3	Atypical meningioma	2	–	Posterior transcallosal interhemispheric	Park bench	Subtotal
29	F	50	Headache, vision loss, gait unsteadiness, sleep disturbances, right inferior quadrantanopia	3	Transitional meningioma	1	–	Combined supracerebellar infratentorial and right occipital interhemispheric approach	Park bench	Total
30	M	64	Headache, memory loss, vision loss	20	Pineal parenchymal tumor of intermediate differentiation	2	ETV + biopsy
31	F	60	Headache, diplopia, vision loss, N&V	13	Pinealoma	1	ETV + biopsy
32	F	64	Headache, diplopia, vision loss	36	Pinealoma	1	ETV + biopsy
33	M	59	Headache, diplopia, vision loss, noise in the ears	12	Pineal parenchymal tumor of intermediate differentiation	3	ETV + biopsy
34	M	58	Left-sided hemiparesis	Died 3 mo later	B-cellular lymphoma	–	ETV + biopsy + ventriculoperitoneal shunt placement
35	M	52	Headache, vision loss, memory loss, sleep deprivation	16	Pineoblastoma	4	ETV + biopsy

Abbreviations: ETV, endoscopic third ventriculostomy; N&V, nausea and vomiting.

Surgical Techniques and Approach Selection

The decision-making process for selecting surgical approaches at our institution is depicted in [Fig. 1]. One patient underwent surgery in a semi-sitting position using the posterior transfalcine interhemispheric approach. Six procedures utilized an infratentorial supracerebellar approach with the patient seated. Eight patients were operated on while lying face down (four cases via infratentorial supracerebellar approach, three cases with OTAs, and one case employing the posterior transcallosal interhemispheric approach). The remaining surgeries were performed with the patients positioned in a modified park bench position: 8 via the infratentorial supracerebellar approach, 4 via the posterior transfalcine interhemispheric approach, 2 via the OTA, and 1 through a combination of supracerebellar infratentorial and right occipital interhemispheric approaches.

Postoperative Outcome

[Table 1] describes patient data with follow-up examinations; unfortunately, it was difficult to report a reason for mortality for some patients. Patients were sedated and transferred to the neurocritical care unit with their heads elevated 30 degrees. Anesthetic medications were gradually discontinued over the next 6 to 8 hours. A computed tomography (CT) scan was performed the morning after surgery to check for postoperative bleeding or other complications, such as hydrocephalus. Discharge typically occurred 5 to 7 days after surgery, with follow-up examinations scheduled at 1 week, 1 month, and 6 months postdischarge.

Following tumor removal, transient Parinaud's syndrome was observed in 30% of cases. However, Parinaud's syndrome, whether present preoperatively or postoperatively, resolved within 2 months after surgery in all patients. Patient number 8 experienced akinetic mutism. We had no in-hospital mortality in this series of patients.

Case Examples

Case Example 1: Posterior Transfalcine Interhemispheric Approach (Case No. 28)

A 64-year-old woman sought evaluation due to persistent headaches in the parietal region, accompanied by pressing sensations, blood pressure instability, general weakness, sleep disturbances, and memory loss over the past 6 months. She had a medical history of hepatitis C and arterial hypertension. MRI revealed a tumor located in the quadrigeminal cistern with supra- and subtentorial growth, extending over the direct sinus and right parietal lobe (see [Fig. 3], top row), along with internal hydrocephalus and cortical atrophy. The provisional diagnosis suggested meningiomatosis. A neurological examination indicated motor deficits, such as instability in the Romberg pose, and coordination test errors on the left side. The surgical procedure commenced with a right occipital median linear skin incision. Two burr holes were created in the superior sagittal sinus and torcula, facilitating the elevation of a bone flap to expose the dural venous sinuses. The straight sinus was visualized during interhemispheric dissection, facilitating the separation of the tentorium. To enhance transfalcine exposure, the inferior sagittal sinus and falx were split. Suturing was performed upon bleeding from the direct sinus (see [Fig. 4A]). Subsequently, an incision was made in the supraposterior arachnoid overlaying the tumor and quadrigeminal cisterns, extending diagonally through the splenic lateral section (see [Fig. 4B]). This provided a view of the junction between the internal and great cerebral veins, situated below the splenium and just above the pineal gland. Following meticulous dissection, the meningioma was completely excised. Duraplasty was performed using the periosteum. The surgery contributed to stabilizing arterial pressure, leading to an improvement in the patient's overall well-being. A follow-up MRI 3 months later revealed complete absence of the tumor (see [Fig. 3], bottom row).

Fig. 3 (A–C) Postcontrast T1-weighted images demonstrating falcotentorial meningioma with sinus invasion and brainstem compression. (D–F) Postoperative images demonstrating complete tumor removal.

Fig. 4 Intraoperative photograph demonstrating pineal region meningioma resection. (A) Suturing sinus bleeding (big white arrow)—hemostatic agent (Surgicel) applied on the bleeding site. (B) Meningioma resection after identifying anatomical orientation and a basal vein of Rosenthal (small white arrow). (C) Cutting the tentorium.

Case Example 2: Occipital Transtentorial Approach (Case No. 18)

A 57-year-old man, with a history of thyroidectomy, presented to our clinic complaining of headaches and general weakness, 3 months after symptom onset. Initial CT examination indicated signs of a PR meningioma (see [Fig. 5], top row). The preoperative plan involved posterior median osteoplastic trepanation through an OTA. A U-shaped skin incision was made, with burr holes positioned near the midline and above the torcula, followed by a parieto-occipital craniotomy. The dura was opened in a C shape and retracted, allowing access to the occipital lobe. The craniotomy was fashioned in such a way that the transverse sinus, superior sagittal sinus, and falx were visible. Incising the tentorium adjacent and parallel to the straight sinus provides access to the quadrigeminal cistern without requiring cerebellar retraction. Next, the microscope is angled superomedially toward the splenium, and the incision is continued until the free edge is reached. The tumor was reached through meticulous dissection, accessing a gap formed by venous structures. Complete tumor removal was achieved without complications (see [Fig. 5], bottom row).

Fig. 5 (A–C) Computed tomography images demonstrating supratentorial meningioma with sinus invasion and brainstem compression. (D–F) Postoperative magnetic resonance imaging T1-weighted images demonstrating complete removal of the meningioma.

Case Example 3: Supracerebellar Infratentorial Approach (Case No. 26)

A 65-year-old man, with a history of insulin-dependent diabetes mellitus (type II), was referred to our neurosurgery department due to falling attacks experienced over the previous 2 months. Brain MRI revealed a space-occupying lesion in the PR causing internal occlusive hydrocephalus (see [Fig. 6], top row). A neurosurgical evaluation confirmed the diagnosis, leading to a recommendation for surgical intervention at our center. Initially, an endoscopic triventriculostomy with biopsy was performed to address the hydrocephalus. Histological analysis revealed a malignant neoplasm of the pineal gland, classified as pinealoma of intermediate malignancy (WHO grade 3). After 6 months, a follow-up examination showed a slight tumor growth, prompting the patient to proceed with tumor removal. The patient was positioned in a park bench position and a midline suboccipital craniotomy was performed. The dura mater was incised with an inverse semicircular incision, extending the full width of the craniotomy and originating at the transverse sinuses. Arachnoid adhesions were carefully dissected, and any encountered midline bridging veins were cauterized, allowing the cerebellum to descend from the tentorium due to gravity. Lateral bridging veins were preserved as much as possible to maintain cerebellar venous drainage. The cisterna magna was opened to facilitate CSF aspiration, and no retractor was applied to the cerebellum. The arachnoid dissection typically begins on the upper left side and progresses further for enhanced anatomical orientation. Preserving as many small veins draining the cerebellum as feasible is of paramount importance in this surgical procedure. Following meticulous arachnoid dissection, the tumor can be successfully removed. Postoperative CT (see [Fig. 6], bottom row) demonstrated complete tumor removal, and the patient's postsurgery condition showed preserved muscle tone and strength, lively tendon reflexes, and no meningeal signs.

Fig. 6 Preoperative magnetic resonance imaging demonstrating pineal region tumor with (A) aqueductal compression and (B, C) ventriculomegaly with the internal cerebral veins being pushed aside. (D–F) Postoperative computed tomography images demonstrating complete tumor removal.

Survival Analysis

Complete tumor resection was achieved in 55% of the patients. Regarding neurological status, follow-up, and survival, the mean follow-up duration was 49.1 months, with five patients lost to follow-up. The mortality rate was 13.7% in the open surgical group and 15.625% in the ETV group. The Kaplan–Meier survival rate is illustrated in [Fig. 7]. After discharge, the patients were referred for oncology consultations. The patients with intermediate differentiation pineocytomas and PPTs who underwent complete surgical excision did not receive adjuvant therapy. However, the individuals diagnosed with pineoblastomas received postoperative radiotherapy, with two patients also undergoing adjuvant chemotherapy. Radiotherapy was also administered to patients with glial tumors, and those with grade 3 to 4 glial tumors received adjuvant chemotherapy. Additionally, postoperative radiotherapy was recommended for two germinoma patients. The patients diagnosed with meningiomas did not necessitate any additional therapy.

Fig. 7 Kaplan–Meier curves show survival dependent on (A) histological examination and (B) the extent of resection.

Discussion

PR tumors are exceptionally rare, particularly in adults, and account for only 1% of cases in adults. In contrast, they are more frequently encountered in pediatric patients, accounting for 3 to 11% of cases.[5] Moreover, accessing the PR tumors poses technical challenges due to its small surgical workspace and complex anatomical relationships with surrounding neurovascular structures.[3] In this study, we performed a retrospective analysis of 35 PR tumors investigating patient positioning in surgeries and comparing neurological outcomes between different approaches.

The diversity of histological tumor types in the PR is attributed to the presence of various cell types in this anatomical area. According to data from the Surveillance, Epidemiology, and End Results (SEER) program, germ cell and PPTs make up 89% of all tumors identified in this region.[13] [16] Another French research team documented the following distribution: 27% of tumors were GCTs and 27% were PPTs.[17] In our study, we found the following distribution: 18.75% were PPTs, 12.50% were GCTs, and 68.75% were TATs. This is a little different from the medical literature. Furthermore, the role of surgery in treating tumors of the PR varies significantly based on the histological type.[18] For example, surgery serves a vital function in germinomas by providing biopsy material, yet the primary treatment approach involves a combination of chemotherapy and radiotherapy. Conversely, for teratomas and GCTs, radical surgery becomes the primary treatment method if the lesion reappears after complete disappearance on imaging and when tumor markers show negativity.[18] However, prior to open craniotomy, it is important to address obstructive hydrocephalus through preoperative procedures. Neuroendoscopic biopsy of PR tumors has proven to be effective and safe, with a diagnostic yield of 95.8% and an accuracy rate of 92.3%. Following histological confirmation, only a small percentage of patients (28.6%) underwent initial surgical resection of the pineal lesion.

We have encountered similar situations where patients opt against undergoing surgery after a third ventriculostomy, with both mortality and morbidity rates at 0%. A notable application of intraventricular endoscopy involves performing ETV and tumor biopsy for individuals with a pineal tumor and noncommunicating hydrocephalus.[19] In our retrospective analysis, 23 patients underwent shunt placements, including Arendt placement, ETV, and ventriculoperitoneal shunt placement. Following the endoscopic procedures, no neurological deficits were observed. Moreover, 17 patients who received shunt placements opted for pineal tumor excision. The shortest postoperative life expectancy recorded was 2 months, noted in a patient diagnosed with pineoblastoma.

During the 1980s, Ausman et al introduced a modified three-quarter prone approach to accessing the PR, where surgery was performed with the patient's head positioned three-quarter prone, with the operated side facing downward.[20] This position, often termed “park bench” with specific adjustments, was adopted in our institution as well, enabling effective exposure of the lesions. In this regard, we utilized this position in 13 cases and attained complete resection in 9 instances. This position facilitated superior access to the PR and posterior third ventricle ensured comfort for both the surgeon and the assistant, lowered the risk of venous air embolism compared with sitting, and necessitated minimal occipital lobe retraction, thanks to the natural descent of the occipital lobe assisted by CSF and ventricular drainage, without the need for active retraction.

As suggested by Morgenstern and Souweidane,[19] the optimal surgical approach should be tailored to each patient, considering factors such as ventricle size, tumor position relative to surrounding structures, massa intermedia size, and surgical goals. Given that most pineal tumors are midline infratentorial, the midline SCIA offers the most direct route to the surgical target.[21] Moreover, since most pineal tumors are situated ventrally to the deep diencephalic venous systems, this corridor offers effective tumor exposure while minimizing impact on the veins. At our institution, we perform this procedure with patients positioned on the park bench configuration, circumventing the disadvantages associated with the sitting position,[20] which include risks like venous air embolism, hypotension, pneumocephalus, macroglossia, quadriplegia, and nerve injuries.[22]

Additionally, it is essential to consider the manual fatigue experienced by neurosurgeons. However, the OTA has its limitations, including challenges related to anatomical alignment and appropriate tentorium division, navigating around deep venous veins, and the risk of homonymous hemianopsia due to occipital lobe retraction. Overall, this method is considered time-consuming and poses risks to several vital structures. Nonetheless, it remains a viable option when tumors have displaced deep veins caudally or posteriorly, making the SCIA unsafe.[23] The posterior interhemispheric transfalcine approach is suitable for tumors originating dorsally or rostrally and extending into deep venous networks, displacing veins ventrally. This pattern often presents in PR masses that resemble tectal and posterior thalamic malignancies.[24] This approach involves accessing the tumor via an interhemispheric corridor along the parieto-occipital junction. By dividing the splenium, the tumor is exposed beneath it. While this approach offers a direct path to tumors located dorsal to the deep venous system, it may result in a partial disconnection syndrome if the splenium remains unaffected by the tumor. Moreover, it poses a risk to the internal cerebral veins.[12]

This study has several limitations that need to be acknowledged. First, being a retrospective study, it is susceptible to bias inherent in such designs. The primary concern lies in the selection bias, which is inevitable due to the single-center retrospective nature of the data and the relatively small sample size, suggesting that outcomes might differ when the research is conducted on a larger scale. The rarity of PR tumors further exacerbates this issue, making it challenging to conduct prospective studies or randomized trials. Consequently, it is crucial to interpret the results of this study while considering the inherent selection bias. We recommend future researchers recruit larger sample sizes through multicentric studies.

Conclusion

PR tumors are uncommon, and not all neurosurgical centers in developing countries have the capability to readily perform resection of PR lesions. Anesthesiological factors also contribute to the decision-making process. Correct patient positioning and choice of the most suitable surgical approach are crucial for attaining a favorable outcome in such intricate cases.

Conflict of Interest

None declared.

Note

The study was conducted in accordance with the Declaration of Helsinki, and approved by Ethics Committee of National Center for Neurosurgery (protocol code no. 7 on December 12, 2023).

Ethical Approval

The Ethical Committee provided ethical approval for this study (number 7 of ethical approval on December 12, 2023). In addition, the investigators ensured that the study conforms to the principles of the Declaration of Helsinki (last revised in 2013) and was conducted in accordance with the ICH Guideline for Good Clinical Practice.

Patients' Consent

Written informed consent was obtained from the patient for publication and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

• References

• 1 Abecassis IJ, Hanak BW, Ellenbogen RG. Pineal region tumors. In: Ellenbogen RG, Sekhar L, Kitchen N. eds. Principles of Neurological Surgery. Philadelphia, PA: Elsevier;; 2018: 602-621.e2
• 2 Simon E, Afif A, M'Baye M, Mertens P. Anatomy of the pineal region applied to its surgical approach. Neurochirurgie 2015; 61 (2–3): 70-76
• 3 Feigl GC, Britz G, Staribacher D, Kuzmin D. The minimally invasive lateral occipital infracortical supra-/transtentorial approach in surgery of lesions of the pineal region: a possible alternative to the standard approaches. World Neurosurg 2023; 172: e151-e164
• 4 Ferrer E, Santamarta D, Garcia-Fructuoso G, Caral L, Rumià J. Neuroendoscopic management of pineal region tumours. Acta Neurochir (Wien) 1997; 139 (01) 12-20 , discussion 20–21
• 5 Favero G, Bonomini F, Rezzani R. Pineal gland tumors: a review. Cancers (Basel) 2021; 13 (07) 1547
• 6 Kong Z, Wang Y, Dai C, Yao Y, Ma W, Wang Y. Central nervous system germ cell tumors: a review of the literature. J Child Neurol 2018; 33 (09) 610-620
• 7 Zhang Z, Wang H, Cheng H. et al. Management of hydrocephalus secondary to pineal region tumors. Clin Neurol Neurosurg 2013; 115 (09) 1809-1813
• 8 Pople IK. Hydrocephalus and shunts: what the neurologist should know. J Neurol Neurosurg Psychiatry 2002; 73 (suppl 1): i17-i22
• 9 Hernesniemi J, Romani R, Albayrak BS. et al. Microsurgical management of pineal region lesions: personal experience with 119 patients. Surg Neurol 2008; 70 (06) 576-583
• 10 Silva JAGD, Santos Jr AAD, Costa MdoD, Almeida EBD. Suboccipital craniectomy with opening of the fourth ventricle and duraplasty: study of 192 cases of craniovertebral malformations. Arq Neuropsiquiatr 2013; 71 (9A): 609-614
• 11 Samii M, Gerganov VM. Giant meningiomas of the posterior fossa. J Neurosurg 2010; 112 (05) 905-906 , discussion 906
• 12 Patel PG, Cohen-Gadol AA, Mercier P, Boop FA, Klimo Jr P. The posterior transcallosal approach to the pineal region and posterior third ventricle: intervenous and paravenous variants. Oper Neurosurg (Hagerstown) 2017; 13 (01) 77-88
• 13 Mavarez-Martinez A, Israelyan LA, Soghomonyan S. et al. The effects of patient positioning on the outcome during posterior cranial fossa and pineal region surgery. Front Surg 2020; 7: 9
• 14 Kobayashi S, Sugita K, Tanaka Y, Kyoshima K. Infratentorial approach to the pineal region in the prone position: Concorde position. Technical note. J Neurosurg 1983; 58 (01) 141-143
• 15 Little KM, Friedman AH, Fukushima T. Surgical approaches to pineal region tumors. J Neurooncol 2001; 54: 287-299
• 16 Al-Hussaini M, Sultan I, Abuirmileh N, Jaradat I, Qaddoumi I. Pineal gland tumors: experience from the SEER database. J Neurooncol 2009; 94 (03) 351-358
• 17 Mottolese C, Szathmari A, Beuriat PA. Incidence of pineal tumours. A review of the literature. Neurochirurgie 2015; 61 (2–3): 65-69
• 18 Frappaz D, Dhall G, Murray MJ. et al. EANO, SNO and Euracan consensus review on the current management and future development of intracranial germ cell tumors in adolescents and young adults. Neuro-oncol 2022; 24 (04) 516-527
• 19 Morgenstern PF, Souweidane MM. Pineal region tumors: simultaneous endoscopic third ventriculostomy and tumor biopsy. World Neurosurg 2013; 79 (02) 18.e9-18.e13
• 20 Ausman JI, Malik GM, Dujovny M, Mann R. Three-quarter prone approach to the pineal-tentorial region. Surg Neurol 1988; 29 (04) 298-306
• 21 Schulz M, Afshar-Bakshloo M, Koch A. et al. Management of pineal region tumors in a pediatric case series. Neurosurg Rev 2021; 44 (03) 1417-1427
• 22 Azab WA, Nasim K, Salaheddin W. An overview of the current surgical options for pineal region tumors. Surg Neurol Int 2014; 5 (01) 39
• 23 Dallier F, Di Roio C. Sitting position for pineal surgery: some anaesthetic considerations. Neurochirurgie 2015; 61 (2–3): 164-167
• 24 Katyal A, Jadhav A, Katyal A. et al. Occipital transtentorial approach for pineal region lesions: addressing the controversies in conventional teaching. Surg Neurol Int 2021; 12: 503

Publication History

Article published online:
30 December 2024