Functional outcomes and anatomy-based surgical strategy in 57 pineal region tumors

Abstract

Background:

Pineal region tumors are uncommon lesions that present significant surgical challenges due to their deep location, proximity to critical neurovascular structures, and frequent association with obstructive hydrocephalus. Although several operative corridors are available, factors influencing postoperative functional recovery remain poorly defined. This study evaluated clinical, radiological, and surgical determinants of functional outcomes following surgery for pineal region tumors.

Methods:

We retrospectively reviewed 57 consecutive patients who underwent surgical treatment for pineal region tumors between March 2016 and August 2025 at a tertiary neurosurgical center. Clinical, radiological, operative, pathological, and follow-up data were analyzed. Functional outcomes were assessed using the Karnofsky Performance Scale (KPS). Primary functional outcome was postoperative change in ΔKPS, with admission KPS analyzed separately to identify baseline determinants of preoperative functional status.

Results:

The mean age was 36.5 years, and 59.6% of patients were male. Gross total resection was achieved in 42 patients (73.7%), subtotal resection in 7 (12.3%), and biopsy alone in 8 (14.0%). Hydrocephalus was present in 45 patients (78.9%), with 12 (21.1%) ultimately requiring permanent cerebrospinal fluid diversion. The posterior interhemispheric transsplenial approach was the most commonly used surgical corridor (36.8%). Increasing age and larger tumor volume independently predicted lower admission KPS scores, whereas lower preoperative KPS was associated with greater postoperative functional improvement. Surgical approach, extent of resection, pathology, and hydrocephalus treatment strategy were not significantly associated with functional recovery. The complication rate was 10.5%, with one perioperative mortality.

Conclusion:

Favorable functional outcomes and high resection rates can be achieved using multiple microsurgical and endoscopic approaches when operative corridor selection is tailored to individual anatomy. Within the limitations of this retrospective cohort, postoperative functional recovery was more strongly associated with baseline patient- and tumor-related factors than with the operative corridor selected. No statistically significant association between surgical approach and postoperative functional recovery was identified.

INTRODUCTION

The pineal region remains one of the most surgically demanding areas in neurosurgery due to its deep-seated location, proximity to critical neurovascular structures, and the frequent need for tissue diagnosis and cerebrospinal fluid diversion. Pineal region tumors are uncommon, accounting for approximately 0.5–1.6% of all intracranial neoplasms, and only a subset of these lesions are suitable for surgical resection.[3,9,11] Existing literature largely consists of single-center case series in which the choice of surgical approach is determined by surgeon preference, expertise, and lesion characteristics. Consequently, reported outcomes have primarily focused on the extent of resection and short-term postoperative results. The availability of multiple microsurgical corridors has expanded the neurosurgical armamentarium for managing these anatomically complex lesions; however, comparative data regarding their impact on long-term functional outcomes remain limited. Furthermore, few studies have examined the influence of perioperative factors and surgical approach selection on patient recovery and quality of life.

Recent advances in molecular neuropathology and the publication of the 2021 World Health Organization (WHO) Classification of Central Nervous System Tumors have substantially refined the diagnostic framework for pineal region neoplasms, improving understanding of their biological behavior and prognostic heterogeneity.[9,22] Simultaneously, developments in microsurgical techniques, neuroendoscopy, neuronavigation, and perioperative neurocritical care have expanded the therapeutic options available for these anatomically challenging lesions. Nevertheless, most contemporary studies continue to report outcomes associated with a single preferred operative corridor, limiting the ability to determine whether postoperative recovery is influenced primarily by surgical approach selection or by patient- and tumor-specific factors. Furthermore, relatively few investigations have focused on longitudinal functional outcomes following surgical treatment of pineal region tumors. The present study aimed to evaluate the relationship between baseline clinical and radiological characteristics, surgical approach, extent of resection, hydrocephalus management, and functional outcomes in a contemporary cohort of 57 surgically treated pineal region tumors. We hypothesized that patient-related factors, including age, tumor burden, and preoperative functional status, would exert a greater influence on postoperative recovery than the specific operative corridor selected.

MATERIALS AND METHODS

Study design and patient selection

We conducted a retrospective cohort study of all patients who underwent surgical management of pineal region tumors at our institution between March 2016 and August 2025. Surgical management included either tumor resection or stereotactic/open biopsy. Patients of all age groups were eligible for inclusion. For subgroup analyses, pediatric patients were defined as those aged <18 years at the time of surgery.

Clinical records, operative reports, and radiological data were reviewed to obtain demographic, clinical, and perioperative information. Variables collected included surgical approach, histopathological diagnosis, extent of resection, intensive care unit (ICU) stay, length of hospital stay (LOS), tumor size and volume, duration of follow-up, Karnofsky performance scale (KPS) scores at admission and at the most recent follow-up, and the presence and management of hydrocephalus before and after surgery. All perioperative medical and neurological complications were systematically recorded.

Preoperative magnetic resonance imaging (MRI) was performed in all patients for lesion characterization and surgical planning. Computed tomography (CT) was obtained in the immediate postoperative period to evaluate the extent of resection and identify surgery-related complications [Figures 1-3]. Follow-up MRI studies were routinely performed at 3 months and 12 months after surgery to assess residual disease, tumor recurrence, and radiological progression.

Figure 1:

(a) Axial T2-weighted magnetic resonance imaging (MRI) demonstrating a lobulated, heterogeneously hyperintense mass in the pineal region causing effacement of the quadrigeminal cistern and compression of the tectal plate. The lesion exerts mass effect on the adjacent midbrain and thalami, with marked dilatation of the lateral and third ventricles suggestive of obstructive hydrocephalus. (b) Axial fluid-attenuated inversion recovery MRI showing the same lesion with heterogeneous signal intensity and surrounding periventricular hyperintense signal changes consistent with transependymal cerebrospinal fluid seepage. The dilated temporal horns and third ventricle further confirm significant obstructive hydrocephalus secondary to aqueductal compression.

Figure 3:

Axial non-contrast computed tomography brain images obtained in the immediate postoperative period demonstrating near-total resection of the pineal region mass. The operative cavity is seen in the pineal region with postoperative changes including pneumocephalus and minimal hyperdense blood products within the resection bed. The lateral and third ventricles appear decompressed compared to preoperative imaging, with no evidence of acute hemorrhage, significant residual tumor, or hydrocephalus.

Figure 2:

(a) Sagittal T2-weighted magnetic resonance imaging (MRI) revealing the same lesion heterogeneous hyperintensity, causing compression of the quadrigeminal plate and complete effacement of the cerebral aqueduct, resulting in obstructive hydrocephalus. Upward displacement of the splenium of the corpus callosum and superior colliculi is evident, along with anterior bowing of the third ventricular floor. (b) Coronal T2-weighted MRI showing the same lesion producing symmetric compression of the bilateral thalami and tectal plate, with marked dilatation of the lateral and third ventricles. Hyperintense periventricular signal changes represent transependymal cerebrospinal fluid seepage secondary to raised intraventricular pressure.

The extent of resection was determined using postoperative imaging and categorized as gross-total resection, subtotal resection, partial resection, or biopsy only, as appropriate. Functional outcomes were assessed using KPS scores at presentation and at the most recent follow-up evaluation.

This study was conducted in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology guidelines for observational cohort studies.

Inclusion criteria

Patients meeting one or more of the following criteria were included:

1. Pineal region lesion producing significant mass effect or neurological deficits

2. Requirement for histopathological confirmation of diagnosis

3. Tumor considered surgically accessible based on preoperative imaging and multidisciplinary evaluation

4. Obstructive hydrocephalus secondary to aqueductal compression.

Exclusion criteria

Patients were excluded if they met any of the following criteria:

1. Patients with markedly elevated serum and/or cerebrospinal fluid alpha-fetoprotein (AFP) and β-human chorionic gonadotropin (β-hCG) levels who were managed without surgical intervention due to a presumed diagnosis of non-germinomatous germ cell tumor were excluded. Patients who underwent surgical treatment despite elevated tumor markers were included in the study.

2. Evidence of disseminated intracranial or spinal disease at presentation.

3. Incomplete clinical data or loss to follow-up.

4. Significant medical comorbidities precluding surgical intervention.

Statistical analysis

Descriptive statistics were used to summarize demographic, clinical, radiological, and operative variables. Continuous variables are presented as mean ± standard deviation (SD) or median with interquartile range (IQR), as appropriate, while categorical variables are expressed as frequencies and percentages.

Bivariate associations between clinical, radiological, and surgical variables were assessed using analysis of variance, linear regression, Kruskal–Wallis tests, or Fisher’s exact tests, according to the distribution and type of data analyzed.

Two separate multivariable linear regression models were constructed to address distinct study objectives. The first model evaluated determinants of admission KPS score to identify factors associated with baseline functional status at presentation. The second model evaluated determinants of postoperative functional improvement, defined as the change in ΔKPS between admission and the most recent follow-up. Variables demonstrating significant associations on univariate analysis were entered into the respective multivariable models to identify independent factors associated with baseline functional status and postoperative recovery while adjusting for potential confounding variables. Histological diagnosis was included as a covariate in the multivariable analyses to account for potential differences in tumor biology and clinical behavior among the various pathological subtypes.

Functional status was evaluated using the KPS at admission, 2 months postoperatively, and at the most recent clinical follow-up. Although the KPS is an ordinal measure, mean KPS values were reported to facilitate comparison with previous neurosurgical literature, where this approach is commonly adopted. Statistical significance was defined as a two-tailed p < 0.05.

All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) Statistics for Windows, Version 17.0 (SPSS Inc., Chicago, IL, USA).

Surgical approaches

The following surgical techniques were employed in this series: (1) endoscopic pineal biopsy combined with endoscopic third ventriculostomy (ETV); (2) the supracerebellar infratentorial (SCIT) approach [Figure 4];[6,14,20] (3) the posterior interhemispheric transsplenial approach;[1,15,23] (4) the anterior transchoroidal fissure approach,[1,4,5,15,23] performed through either a frontal transcortical or an interhemispheric transcallosal corridor; and (5) the occipital transtentorial (OTT) approach.[17-19]

Figure 4:

Supracerebellar infratentorial (SCIT) approach. (a) Operative exposure following suboccipital craniotomy demonstrating the supracerebellar operative corridor toward the pineal region. (b) Patient positioning in the sitting position for the SCIT approach. Although the deep venous complex is not clearly visualized in this image, careful preservation of the internal cerebral veins, vein of Galen, and basal veins of Rosenthal is a fundamental principle of this approach.

In patients with suspected germ cell tumors or in cases requiring histopathological confirmation before definitive treatment, endoscopic biopsy with simultaneous ETV was performed to establish the diagnosis and address obstructive hydrocephalus.[2] The choice of surgical approach was individualized based on tumor location, size, extension, relationship to adjacent neurovascular structures, ventricular anatomy, and the presumed pathological diagnosis. Selection of the operative corridor aimed to maximize surgical exposure while minimizing brain retraction and manipulation of critical neural structures.

Patient positioning was determined according to the selected operative corridor and tumor anatomy. The SCIT approach was generally performed with the patient in the sitting position to facilitate gravitational cerebellar relaxation and venous drainage. OTT procedures were typically performed in the three-quarter prone position. Posterior interhemispheric transsplenial approaches were performed with the patient in the park-bench or supine position with the head appropriately rotated to optimize interhemispheric access. Anterior interhemispheric transcallosal approaches were performed with the patient in the supine position. Final positioning was individualized according to tumor location, venous anatomy, and surgeon preference.

Neuronavigation was used selectively in cases where it was considered beneficial for operative planning and trajectory guidance, particularly in patients with distorted ventricular anatomy, deep-seated lesions, or altered anatomical landmarks. Intraoperative neurophysiological monitoring was not routinely employed. In selected cases, endoscope-assisted microsurgical resection was performed using a 30° rigid endoscope to improve visualization of deep operative corridors.

Intraoperative neurophysiological monitoring was available at our institution but was not routinely employed for pineal region surgery. Monitoring modalities, including motor-evoked potentials, somatosensory-evoked potentials, and brainstem auditory-evoked potentials, were used selectively at the discretion of the operating surgeon in cases where tumor characteristics or the anticipated surgical trajectory suggested an increased risk of injury to eloquent neural pathways or brainstem structures. Routine monitoring was not considered necessary for all pineal region procedures because the operative corridors primarily involved the midline posterior incisural region without direct manipulation of the corticospinal tracts or auditory pathways.

Intraoperative frozen-section analysis was not routinely performed. Given the characteristic radiological features of many pineal region lesions and the feasibility of definitive resection through established microsurgical corridors, frozen-section evaluation was reserved for selected cases, in which the pathological diagnosis was expected to influence the extent of surgical intervention.

RESULTS

A total of 57 patients underwent surgical management for pineal region tumors during the study period [Table 1]. The mean age at surgery was 36.5 years, with 23 patients (40.4%) being female and 34 (59.6%) male. The mean admission KPS score was 86, and 16 patients (28.1%) presented with a KPS score below 70. Gross total resection (GTR) was achieved in 42 patients (73.7%), subtotal resection (STR) in 7 (12.3%), and biopsy alone in 8 (14.0%).

Table 1:

Overview of patient characteristics.

Headache was the most common presenting symptom, occurring in 42 patients (73.7%), followed by nausea and vomiting in 24 (42.1%), diplopia in 15 (26.3%), and Parinaud syndrome in 10 (17.5%). Ataxia and constitutional symptoms were each present in 6 patients (10.5%). Less frequent presenting manifestations included dizziness, seizures, cognitive or personality changes, sensory disturbances, ocular movement abnormalities, galactorrhea, transient ischemic attacks, loss of consciousness, urinary or fecal incontinence, and incidental lesions, each occurring in fewer than 10% of patients.

Tumor markers

Serum tumor markers were evaluated in 28 patients (49.1%). Elevated AFP was identified in 4 patients (7.0%), isolated β-hCG elevation in 1 patient (1.8%), and concurrent AFP and β-hCG elevation in 1 patient (1.8%). Twenty-two patients (38.6%) had normal serum tumor marker levels, while tumor markers were not assessed in 29 patients (50.9%) [Table 2]. Serum tumor marker assessment was performed selectively according to the preoperative clinical and radiological suspicion of a germ cell tumor; therefore, tumor marker evaluation was not available for all patients. No statistically significant association was observed between elevated serum tumor markers and admission KPS scores.

Table 2:

Elevations and profile of serum tumor markers.

Extent of resection

The distribution of pediatric and adult patients according to surgical approach is summarized in Table 3. For subgroup analysis, pediatric patients were defined as those younger than 18 years; therefore, this subgroup differs from the age category of <20 years, as presented in Table 1. The posterior interhemispheric transsplenial approach was the most frequently employed surgical corridor, accounting for 21 cases (36.8%), followed by the SCIT approach in 17 cases (29.8%) and ETV with biopsy in 9 cases (15.8%). Anterior transchoroidal and OTT approaches were used in 5 (8.8%) and 4 (7.0%) patients, respectively, while a combined SCITOTT approach was performed in one patient.

Table 3:

Conclusive surgical techniques utilized.

Patients who initially underwent ETV for hydrocephalus management and subsequently received definitive microsurgical tumor resection were not included in the ETV/biopsy category. Postoperative MRI was routinely obtained at 3 months and 1 year to assess the extent of resection and tumor recurrence.

Pathology, hydrocephalus, and presentation KPS

Pineoblastoma was the most common histological diagnosis, occurring in 7 patients (12.3%). Other frequent pathologies included pilocytic astrocytoma, pineocytoma, papillary tumor of the pineal region, mixed germinoma, and germinoma, each accounting for approximately 10.5% of cases [Table 4]. Pediatric patients more commonly presented with germ cell tumors, mature teratomas, and pilocytic astrocytomas, whereas pineal parenchymal tumors of intermediate differentiation and papillary tumors tended to have smaller tumor volumes at presentation.

Table 4:

Histological tumors with associated mean patient ages and tumor volumes.

Interpretation of pineal region tumor pathology has evolved considerably following publication of the 2021 WHO Classification of Central Nervous System Tumors, which incorporates molecular and epigenetic characteristics alongside traditional histomorphological criteria.[9,22] Recent studies have demonstrated that molecular subclassification provides important prognostic information for pineal parenchymal tumors and may influence future treatment strategies. Although the present study was conducted over a period during which pathological classification systems evolved, the spectrum of lesions encountered reflects the biological heterogeneity characteristic of pineal region neoplasms. Future investigations integrating molecular profiling with surgical and functional outcomes may further refine patient stratification and prognostic assessment.

For histological subgroups containing a single patient (n = 1), only the observed value is reported because SD cannot be calculated.

The first regression model evaluated factors associated with baseline functional status, as measured by the admission KPS. On univariate analysis, age, tumor volume, ICU length of stay, and total hospital length of stay were significantly associated with admission KPS scores [Table 5]. After adjustment for potential confounding variables, increasing age and larger tumor volume remained independently associated with lower admission KPS scores. Lower admission KPS scores were also associated with longer ICU and overall hospital stays.

Table 5:

Multivariable regression analysis of factors associated with admission Karnofsky performance scale (baseline functional status).

The relatively high proportion of pineoblastoma and germ cell tumors in our cohort may reflect referral bias inherent to a tertiary neurosurgical center serving a large rural and semi-urban population. Similar patterns have been reported from other Asian series, where delayed presentation and limited access to specialized neuro-oncological care may influence the pathological spectrum encountered.

Hydrocephalus was present in 45 patients (78.9%). Patients with hydrocephalus had a lower mean admission KPS score (75 ± 17) than those without hydrocephalus (88 ± 9), although this difference did not reach statistical significance (p = 0.69) [Table 6].

Table 6:

Hydrocephalus as an indicator of KPS at admission.

Management strategies included external ventricular drainage (EVD), ETV, and ventriculoperitoneal shunting (VPS) [Table 7]. Because several patients underwent more than one CSF diversion procedure during the course of treatment, these interventions were not mutually exclusive. Overall, 12 patients ultimately required permanent CSF diversion. Patients with hydrocephalus had lower mean admission KPS scores than those without hydrocephalus, although this difference did not reach statistical significance.

Table 7:

Preoperative hydrocephalus and treatment plan statistics.

Follow-up and functional outcomes

The mean duration of follow-up for the entire cohort was 12 months. Functional outcome was assessed at the most recent available clinical follow-up. One patient with a presenting Glasgow coma scale score of E1VTM2 underwent biopsy and was diagnosed with glioblastoma; this patient died within 1 month of surgery. All patients surviving beyond 2 months demonstrated either stable or improved KPS scores compared with their preoperative baseline. The second regression model evaluated factors associated with postoperative functional improvement (ΔKPS), defined as the change in KPS between admission and the most recent follow-up. Lower admission KPS scores were independently associated with greater postoperative functional improvement [Table 8]. ICU length of stay was also associated with postoperative functional recovery; however, because ICU stay is a postoperative variable, this association should be interpreted as reflecting the postoperative clinical course rather than a true preoperative predictor. No significant associations were identified between postoperative improvement in KPS and patient age, surgical approach, extent of resection, tumor pathology, adjuvant radiotherapy or chemotherapy, preoperative hydrocephalus, hydrocephalus treatment strategy, tumor size, or postoperative cerebrospinal fluid leak.

Table 8:

Factors associated with postoperative functional improvement (ΔKPS).

Complications

There was one perioperative mortality (1.8%), defined as death occurring within 30 days of surgery. This patient presented with a poor neurological status (GCS E₁V_TM₂) and underwent tumor biopsy, which established the diagnosis of glioblastoma.

Postoperative complications occurred in 6 patients (10.5%) [Table 9]. These included one case each of cerebrospinal fluid (CSF) leak (1.8%), intraparenchymal hemorrhage following biopsy (1.8%), and transient cranial nerve IV palsy resulting in ocular motility disturbance (1.8%). Air embolism occurred in 2 patients (3.5%), both of whom were successfully managed by the neuroanesthesia team without permanent sequelae. No statistically significant association was observed between the surgical approach employed and the occurrence of postoperative complications (p = 0.73).

Table 9:

Postoperative complications in total, categorized by surgical method.

The overall postoperative complication rate was 10.5%, with one perioperative mortality (1.8%). The mortality occurred in a patient with extremely poor neurological status at presentation who was subsequently diagnosed with glioblastoma. Other complications included one case each of CSF leak, biopsy-related intraparenchymal hemorrhage, and transient cranial nerve IV palsy, as well as two episodes of intraoperative air embolism. All air embolism events were recognized promptly and managed successfully without long-term sequelae.

The present study also has important implications for surgical decision-making. Whereas many historical series have advocated a preferred operative corridor based on individual surgeon experience, our findings support a more flexible, anatomy-driven strategy. High rates of GTR were achieved across multiple surgical approaches, and neither extent of resection nor complication rates were significantly associated with a particular operative corridor. These observations suggest that favorable outcomes can be achieved using different operative corridors when approach selection is tailored to tumor morphology, ventricular anatomy, venous architecture, and surgeon expertise.

Selection of the operative corridor should also take into account the deep venous anatomy of the pineal region. The internal cerebral veins, vein of Galen, and basal veins of Rosenthal constitute the principal venous structures surrounding pineal region tumors and frequently determine the safest surgical trajectory. Displacement of the internal cerebral veins superiorly or laterally may favor an SCIT approach, whereas tumors extending predominantly into the posterior third ventricle or with superior displacement of the deep venous complex may be more suitable for posterior interhemispheric transcallosal approaches. Similarly, the relationship of the tumor to the vein of Galen and the basal veins of Rosenthal should be carefully evaluated preoperatively, as preservation of these critical venous structures is essential to minimize the risk of venous infarction and neurological morbidity. Consequently, operative corridor selection should be guided by individual tumor anatomy and venous relationships rather than by a preference for any single surgical approach. Such a paradigm may be particularly relevant in contemporary neurosurgical practice, where advances in imaging, neuronavigation, and endoscopic assistance permit increasingly individualized treatment planning.

Analysis of postoperative imaging demonstrated no significant association between the surgical approach and extent of resection [Table 10]. Likewise, the degree of resection was not significantly associated with tumor pathology based on WHO classification [Table 10].

Table 10:

Degree of resection in relation to WHO classification and surgical techniques.

Hydrocephalus developed through multiple pathophysiological mechanisms, most commonly as a consequence of aqueductal obstruction and impaired venous drainage. Hydrocephalus was present in 45 patients (78.9%) at presentation. Management strategies included EVD, ETV, and VPS, with treatment individualized according to ventricular anatomy, tumor characteristics, and clinical status. Because several patients underwent more than one CSF diversion procedure during the course of treatment, these interventions were not mutually exclusive. Overall, 12 patients ultimately required permanent CSF diversion. One patient underwent VPS placement following failure of an initial ETV and development of a postoperative intraparenchymal hemorrhage associated with seizures. These findings support a selective endoscopic strategy while acknowledging that a subset of patients will ultimately require permanent CSF diversion.

For the purposes of this study, radical subtotal resection (STR) was defined as a resection that was considered gross total by the operating surgeon intraoperatively but demonstrated only thin peripheral, non-nodular gadolinium enhancement along the resection cavity on postoperative MRI.

DISCUSSION

Pineal region tumors remain among the most challenging intracranial lesions due to their deep location, intimate relationship with critical venous and brainstem structures, diverse histopathological spectrum, and frequent association with obstructive hydrocephalus. Although several operative corridors have been described, contemporary literature remains dominated by single-approach surgical series, making it difficult to determine whether outcomes are primarily influenced by the selected corridor or by patient- and tumor-specific factors. The present study addresses this gap by analyzing a heterogeneous cohort of 57 surgically treated pineal region tumors managed using multiple microsurgical and endoscopic strategies selected according to anatomical and pathological characteristics.

To the best of our knowledge, this represents one of the few contemporary studies evaluating functional outcome predictors across multiple operative corridors within a single institutional cohort. The principal finding of this study is that postoperative functional recovery was more strongly associated with baseline patient characteristics than with the operative corridor selected. No statistically significant association between surgical approach and postoperative functional recovery was identified after adjustment for the variables included in the analysis. Increasing age and larger tumor volume were independently associated with poorer baseline functional status (admission KPS), whereas poorer admission KPS was associated with greater postoperative functional improvement. Surgical approach, extent of resection, tumor histology, hydrocephalus treatment strategy, and adjuvant therapy were not independently associated with postoperative functional improvement. These findings support the hypothesis that patient-specific factors exert a greater influence on outcome than the choice of surgical corridor itself.

A second important observation is that high rates of tumor resection can be achieved through multiple operative corridors when approach selection is guided by anatomical principles. GTR was obtained in 73.7% of patients despite substantial heterogeneity in tumor size, pathology, and anatomical extension. Furthermore, neither the extent of resection nor complication rates were significantly associated with a specific surgical approach. These findings support an anatomy-based rather than surgeon-preference-based strategy for pineal region surgery. Table 11 summarizes the anatomical considerations influencing approach selection, including the relationship of the tumor to the deep venous system, particularly the internal cerebral veins, vein of Galen, and basal veins of Rosenthal.

Table 11:

General anatomical considerations for the application of diverse surgical approaches to pineal region tumors.[1,3,6,10-21,23]

Comparison with previous literature

The surgical management of pineal region tumors has evolved considerably over the past several decades. Early surgical attempts at pineal tumor excision included historical operative approaches described by Horrax and Jamieson,[7,8] followed by the development and refinement of several microsurgical corridors. Hernesniemi and colleagues reported one of the largest microsurgical experiences, demonstrating the versatility of the SCIT approach across a broad spectrum of pineal region pathologies.[6] Similarly, Oliveira et al. reported favorable resection rates and acceptable morbidity using the SCIT corridor, while Qiu et al. described satisfactory outcomes with the OTT approach for pineal region meningiomas.[14,19] Although these studies established the safety and efficacy of individual surgical approaches, they provided limited comparative information regarding functional outcomes and approach selection.

More recent investigations have increasingly emphasized individualized surgical planning based on tumor anatomy and extension. Contemporary series suggest that no single operative corridor is universally applicable and that optimal exposure depends on tumor location relative to the tectum, deep venous system, tentorium, and ventricular structures. Our findings are consistent with this evolving philosophy. Despite employing multiple surgical approaches, we observed no significant association between operative corridor and extent of resection, complication rate, or postoperative functional improvement, supporting the concept that anatomical suitability may be more important than adherence to a preferred technique.

The present GTR rate of 73.7% compares favorably with previously reported contemporary series. While extent of resection remains an important surgical objective, recent literature has increasingly recognized that preservation of neurological function and quality of life are equally important measures of treatment success. In this regard, the present study demonstrates that increasing age and larger tumor volume were associated with poorer baseline functional status at presentation, while lower admission KPS was associated with greater postoperative functional improvement. No independent association was identified between operative corridor and postoperative functional recovery.

Advances in neuroendoscopy have also influenced the management paradigm for pineal region lesions. Several contemporary studies have highlighted the value of simultaneous ETV and tumor biopsy in patients presenting with obstructive hydrocephalus, particularly when germ cell tumors are suspected.[2] Our institutional experience supports this strategy, as endoscopic management allowed both cerebrospinal fluid diversion and histopathological diagnosis while reducing immediate reliance on permanent CSF diversion procedures.

Furthermore, recent molecular studies and the 2021 WHO Classification of Central Nervous System Tumors have refined the biological classification of pineal region neoplasms.[9,22] Molecular profiling has demonstrated substantial heterogeneity within pineal parenchymal tumors and is increasingly recognized as an important determinant of prognosis and therapeutic decision-making. Although molecular analyses were not uniformly available throughout the study period, future integration of molecular markers with surgical and functional outcome data may further improve risk stratification and individualized treatment planning. Although histological diagnosis was included in the multivariable analyses, the relatively small number of patients within individual pathological subgroups limited the ability to perform adequately powered pathology-specific analyses. Consequently, potential differences in functional outcomes among individual tumor types may not have been detected. Because serum tumor marker testing was performed selectively based on the preoperative clinical and radiological suspicion of germ cell tumors, analyses involving AFP and β-hCG should be interpreted cautiously, particularly given the substantial proportion of patients in whom tumor markers were not assessed.

Hydrocephalus was present in nearly four-fifths of patients at presentation, underscoring its central role in the clinical manifestation of pineal region lesions. Contemporary management increasingly favors endoscopic techniques that simultaneously provide cerebrospinal fluid diversion and tissue diagnosis. In our practice, ETV was preferred whenever anatomical conditions were favorable, particularly in patients with suspected germ cell tumors or those requiring histopathological confirmation before definitive therapy. This strategy aligns with modern endoscopic treatment paradigms and allowed effective management of hydrocephalus while reducing immediate dependence on permanent CSF diversion. Although 12 patients ultimately required long-term CSF diversion, most patients were successfully managed without permanent shunt placement. These findings support the growing role of neuroendoscopy as an integral component of the multidisciplinary management of pineal region tumors.

Unlike many previous reports that have focused primarily on extent of resection and perioperative morbidity, the present study emphasizes longitudinal functional recovery. Recent systematic reviews have highlighted the limited availability of functional outcome data in pineal region tumor surgery and the absence of robust predictors of postoperative recovery. Our findings suggest that baseline neurological condition and tumor burden are more important determinants of functional improvement than the operative corridor selected. Patients presenting with lower KPS scores demonstrated the greatest postoperative gains, indicating that timely intervention may substantially alter neurological trajectory even in individuals with significant preoperative disability. These observations support the incorporation of functional outcome measures alongside traditional surgical metrics when evaluating treatment success in pineal region tumors. Although ICU length of stay was associated with postoperative functional improvement, ICU stay occurs after surgery and, therefore, should be interpreted as reflecting the postoperative clinical course rather than a true preoperative determinant of functional recovery.

Clinical implications

The findings of this study have several important clinical implications. First, they support an anatomy-based approach to pineal region surgery, demonstrating that favorable outcomes can be achieved through multiple operative corridors when approach selection is tailored to tumor morphology and regional anatomy. Second, functional recovery appears to be influenced more strongly by baseline neurological status and tumor burden than by the specific surgical approach employed. Third, the results support the use of ETV as a valuable adjunct in selected patients with hydrocephalus and suspected radiosensitive tumors. Collectively, these observations suggest that individualized treatment planning may be more important than adherence to a single preferred operative corridor. General anatomical considerations for the application of diverse surgical approaches to pineal region tumors are shown in Table 11.

Limitations

Several limitations should be acknowledged. First, the retrospective nature of the study introduces the possibility of selection bias, information bias, and incomplete data collection. Second, despite representing one of the larger contemporary single-center experiences, the cohort size remains modest owing to the rarity of pineal region tumors and the diversity of pathological subtypes encountered. In addition, the study included a heterogeneous spectrum of pineal region tumors with distinct biological behavior, treatment strategies, and prognoses. Although histological diagnosis was included in the multivariable analyses, pooling these pathological entities may have obscured subtype-specific associations and limited the ability to detect differences in outcomes between individual tumor types. Larger multicenter studies with pathology-specific subgroup analyses are warranted. In addition, serum tumor marker assessment was performed selectively according to clinical indication rather than routinely in all patients, limiting the interpretability of analyses involving AFP and β-hCG.

Third, postoperative functional status was assessed using clinical documentation from multiple specialists, including neurosurgeons, radiation oncologists, and neuro-oncologists. Although this approach improved data availability, variability in assessment methodology may have introduced measurement bias. Finally, the mean follow-up duration of 12 months may be insufficient to fully evaluate long-term tumor control, recurrence patterns, and delayed treatment-related morbidity, particularly in patients with low-grade lesions and germ cell tumors. Because the original patient-level follow-up data were unavailable for reanalysis, median follow-up duration, follow-up range, and follow-up completeness at predefined time points could not be reported. In addition, although the KPS is an ordinal measure, mean values were used for consistency with previous neurosurgical studies. Because the original patient-level data were unavailable for reanalysis, median values and IQR could not be calculated retrospectively. Routine intraoperative neurophysiological monitoring was not employed in this series, reflecting institutional practice during the study period. Whether routine monitoring improves functional outcomes in pineal region surgery remains uncertain and warrants further investigation.

Accordingly, the statistical associations identified in this study should be interpreted as observational findings rather than definitive predictors of prognosis. Larger multicenter studies with longer follow-up periods are required to validate these observations and further clarify factors influencing functional and oncological outcomes.

CONCLUSION

In this contemporary cohort of 57 surgically treated pineal region tumors, favorable functional outcomes and high rates of GTR were achieved using multiple microsurgical and endoscopic corridors selected according to anatomical considerations. Increasing patient age and larger tumor volume were associated with poorer baseline functional status, whereas lower preoperative KPS was associated with greater postoperative functional improvement. Within the limitations of this retrospective anatomy-based cohort, no statistically significant association between the operative corridor and postoperative functional recovery was observed. These findings support an individualized, anatomy-based approach to surgical planning; however, they should not be interpreted as demonstrating that one operative corridor is superior to another because surgical approach selection was based on tumor anatomy and surgeon judgment. Future multicenter prospective studies are required to validate these observations and refine evidence-based treatment algorithms for pineal region tumors.

Data availability

The datasets generated and/or analyzed during the current study are not publicly available because they contain patient-identifiable clinical information but are available from the corresponding author on reasonable request and with appropriate institutional approval.

Ethical approval:

Institutional Review Board approval is not required as it is a retrospective study. The study was conducted in accordance with the principles of the Declaration of Helsinki.

Declaration of patient consent:

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

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