Pineal Region Research Articles

Papillary Tumor of the Pineal Region: A Case Report and Literature Review

Pineal tumors of the pineal region (PTPR) are rare neuroepithelial tumors of the central nervous system, and their clinical features often lack specificity, so it is always difficult to make a definite diagnosis before surgery, and the treatment is mainly based on complete surgical resection. We report the case of a 21-year-old male who presented with intermittent dizziness and headache with vomiting for more than 2 months. The imaging revealed a mass in the region of the pineal region with obstructive hydrocephalus. After the hospitalization, the patient underwent a microscopic excision of the pineal mass, and the tissue was sent for histopathological examination and available immunohistochemical tests, which resulted in a definitive diagnosis of a papillary tumor of the pineal region. He had undergone several radiation treatments during his hospitalization and remained recurrence-free until the latest follow-up visit. This article highlights the similarities between this case and the PTPR described in WHO 2021 in terms of clinical presentation, imaging, and histopathological features. Therefore, this case report completes the sample database of PTPRs. By reviewing the literature related to PTPRs, we hope that this report will be helpful to improve the understanding of clinicians and pathologists about this rare tumor. However, more relevant studies are needed to clarify the pathogenesis, prognosis, and optimal treatment options to achieve early diagnosis, early treatment, and improved prognosis.

Mature cystic teratoma of spinal cord in an adult

Aim: Reporting a rare case of mature cystic teratoma of spinal cord in an adult
 Background: Teratomas of the central nervous system are rare lesions accounting for less than 0.5-2% of all CNS tumors. Most of these are found in pediatric age group and favor sellar - suprasellar, pineal and sacro-coccygeal regions. Their occurrence in spinal cord in an adult is incredibly rare.
 Case presentation: A 22-year-old male presented with low back ache and weakness of both lower limbs. Clinical examination and radiological workup revealed presence of a cystic lesion causing diffuse enlargement of the cord from L1 to L5-S1. Histo-pathological examination of the excised lesion revealed it to be teratoma.
 Conclusion and clinical significance: Mature teratoma of the spinal cord in adults is extremely rare occurrence. However, this diagnosis should be kept in mind when evaluating a cystic lesion of cord even in adults. Maximal safe resection of the lesion results in prolonged deficit-free survival.

Upper gastrointestinal bleed as the initial presentation of seminoma involving the duodenum in an elderly patient with 9year follow up: A case report and literature review.

Germ cell tumors are the most common malignancies in males between 20 and 40 years. However, primary extragonadal germ cell tumors are rare and account for 2%-5% of all germ cell neoplasms in adults. Extragonadal germ cell tumors are characterized by their midline locations including pineal and suprasellar regions, mediastinum, retroperitoneum and sacrococcyx. These tumors have also been reported in rare locations such as prostate, bladder, vagina, liver and scalp. Extragonadal germ cell tumors can be primary but may also represent metastases from primary gonadal germ cell tumors. In this report we describe a case of a duodenal seminoma in a 66-year-old male with no history of testicular tumors, who presented with upper gastrointestinal bleed as the initial manifestation. He was effectively treated with chemotherapy and continues to progress well clinically, with no episodes of recurrence.

The Prognosis of Pineal Parenchymal Tumors: Development and Validation of a Nomogram Based on Surveillance, Epidemiology and End Results

Pineal parenchymal tumors are exceedingly rare, and optimal disease management has yet to be defined. In this study, we aimed to identify prognostic factors and establish a predictive model for the prognosis of patients with pineal parenchymal tumors. All patients with pineal parenchymal tumors in the Surveillance, Epidemiology and End Results database between 1975 and 2019 were reviewed. Data were summarized, and survival was modeled with Cox regression analyses. In addition, a nomogram predicting 5- and 10-year survival probability for pineal parenchymal tumors was developed and validated. We found 691 pineal parenchymal and 1961 pineal region neoplasms during 1975 and 2019 resulting in an incidence of 35%. In total, 441 patients were excluded duetoincompletedata. The final cohort was subdivided into groups based on tumor histology: pineocytomas, pineoblastomas, and pineal parenchymal tumors of intermediate differentiation. Multivariate Cox analysis identified age and beam radiation as prognostic factors in pineoblastomas. Age, histology, tumor size, extent of resection, radiation, and chemotherapy were selected to build a clinical nomogram. The C-index for the nomogram was 0.795 (95% confidence interval 0.738-0.852). The calibration curves of the 5- and 10-year survival rates showed good agreement between the nomogram predictions and actual observations. This nomogram is a convenient and precise tool for clinicians to evaluate prognosis of pineal parenchymal tumors.

The parietooccipital interhemispheric transtentorial approach for pineal tumors

Access to the pineal region has always been a challenge for neurosurgeons. The parietooccipital interhemispheric transtentorial approach is a slight variation of the traditional occipital transtentorial approach that provides adequate exposure to the lesions of the pineal region without introducing additional risks. In this study, the modified parietooccipital interhemispheric transtentorial approach is discussed including step-by-step anatomical cadaveric dissections and operative images. 27 adult patients (age > 18) who were operated over a 30-year period (1992–2022) by the senior author (M.N.P.) at two clinics, Marmara University, Department of Neurosurgery, Istanbul, Turkey and Acibadem Mehmet Ali Aydinlar University, Department of Neurosurgery, Istanbul, Turkey were analyzed. Only pineal region tumors were included in the analysis. Falcotentorial meningiomas and vascular lesions including cavernomas were excluded. 5 cadaveric specimens were dissected step by step following the surgical approach. Each step was documented using a Canon EOS 5D Mark II camera with Canon 100 mm Macro Lens. Step by step images of the dissections were presented including comparison with surgical images. Additional illustrations were used to describe the surgical corridor. The surgical corridor is maintained anterior to the parietooccipital sulcus along the medial of the precuneus. No retraction to the calcarine sulcus resulted in no postoperative hemianopsia. The neurovascular structures along the surgical corridor along with the nuances of the tentorium incision and splenium resection are discussed. The parietooccipital interhemispheric transtentorial approach provides a wide and safe corridor for surgical resection of pineal tumors.

Commentary: Defining Occult High-Risk Cysts of the Pineal Region: A Case Series.

Commentary: Defining Occult High-Risk Cysts of the Pineal Region: A Case Series.

Defining Occult High-Risk Cysts of the Pineal Region: A Case Series.

Absence of hydrocephalus on neuroimaging may impart a false sense of security for patients with pineal cysts. In this case series, we characterize a subset of patients with pineal cysts having an occult presentation. Unifying features of worsening paroxysmal headaches suggesting intermittent obstructive hydrocephalus and radiographic evidence of third ventricular invagination characterize these patients as high risk. To define features of occult, high-risk pineal cysts and outcomes of endoscopic cyst fenestration. Charts were retrospectively reviewed for patients with pineal cysts evaluated at our institution between 2018 and 2021 who underwent endoscopic cyst fenestration. To capture cysts presenting as occult, patients were excluded if hydrocephalus was noted at presentation. Relevant clinical history, imaging, operative data, and clinical outcomes were reviewed. Of 50 pineal cyst patients, 4 satisfied inclusion criteria. All patients presented with worsening paroxysmal headaches. In addition, 75% (3/4) also experienced intermittent syncope. Patients exhibited no hydrocephalus (n = 3) or fluctuating ventricular size on longitudinal imaging (n = 1). In all cases, high-resolution sagittal 3-dimensional T2 magnetic resonance imaging demonstrated invagination of the cyst anteriorly into the posterior third ventricle. All patients underwent endoscopic cyst fenestration with complete symptom resolution (mean follow-up of 20.6 months; range 3.5-37.4 months). The clinical history for occult, high-risk pineal cysts is notable for worsening paroxysmal headaches and episodic alterations of consciousness suggesting intermittent obstructive hydrocephalus. Because ventricular size can appear normal on standard imaging protocols, clinical suspicion should trigger workup with high-resolution magnetic resonance imaging designed to detect these cysts. Endoscopic cyst fenestration is a safe and efficacious management strategy.

Simultaneous biportal endoscopic management of pineal region tumors in patients with obstructive hydrocephalus: technical notes

BackgroundThe goal of this study is to show the feasibility and benefits of using the simultaneous biportal endoscopic procedure to treat pineal tumors in patients with obstructive hydrocephalus.MethodsWe retrospectively reviewed three patients with pineal tumors and acute obstructive hydrocephalus who were treated in one session with a frameless stereotactic guided simultaneous biportal endoscopic third ventriculostomy and endoscopic tumor biopsy performed through two separate ports using one rigid ventriculoscope.ResultsIn the three patients, ventriculostomy and endoscopic biopsies were conducted. There was no death or morbidity throughout the 45-min procedure. All of the patients’ histological findings were confirmed. Germinoma was diagnosed in two patients who recieved postoperative radiotherapy, and the third patient diagnosed with a pineocytoma. Magnetic resonance imaging with flow-sensitive sequences was used to confirm ventriculostomy patency in all patients 6 months after the surgery.ConclusionBiportal endoscopic approach enables better visual control of both procedures. Furthermore, it allows the surgeon to safely pass the ventriculoscope via the foramen of monro, even if it is narrow. Moreover, during endoscopic tumor biopsy and third ventriculostomy, the intracranial pressure can be smoothly managed using the outlet tubes accessible. This treatment may be an alternative to traditional uniportal endoscopic operations in certain patients.

Histogenesis of intracranial germ cell tumors: primordial germ cell vs. embryonic stem cell.

Intracranial germ cell tumor (iGCT) is a rare disorder and often occurs during childhood and adolescence. iGCTs are frequently localized in pineal region and hypothalamic-neurohypophyseal axis (HNA). In spite of well-established clinical and pathological entity, histogenesis of iGCTs remains unsettled. Current theories of histogenesis of iGCTs include germ cell theory (from primordial germ cells (PGCs) of aberrant migration) and stem cell theory (transformed embryonic stem (ES) cells). In order to comprehend the histogenesis, we revisit the origin, migration, and fate of the human PGCs, and their transformation processes to iGCT. In "germ cell theory," transformation of ectopic PGCs to iGCT is complex and involves multiple transcription factors. Germinoma is derived from ectopic PGCs and is considered a prototype of all GCTs. Non-germinomatous germ cell tumors (NGGCTs) develop from more differentiated counterparts of embryonic and extra-embryonic tissues. However, there is a distinct genomic/epigenomic landscape between germinoma and NGGCT. ES cells transformed from ectopic PGCs through molecular dysregulation or de-differentiation may become the source of iGCT. "Stem cell theory" is transformation of endogenous ES cells or primitive neural stem cell to iGCTs. It supports histological diversity of NGGCTs because of ES cell's pluripotency. However, neural stem cells are abundantly present along the subependymal zone; therefore, it does not explain why iGCTs almost exclusively occur in pineal and HNA locations. Also, the vast difference of methylation status between germinoma and NGGCT makes it difficult to theorize all iGCTs derive from the common cellular linage. Transformation of PGCs to ES cells is the most logical mechanism for histogenesis of iGCT. However, its detail remains an enigma and needs further investigations.

BCOR expression in paediatric pineoblastoma.

BCOR is expressed in a new brain tumour entity, i.e. 'CNS tumour with BCOR internal tandem duplication' (HGNET BCOR) but not in several other high grade paediatric brain tumours investigated. Immunohistochemical detection of BCOR expression may therefore serve as a potential diagnostic marker. Nevertheless, in rare paediatric glioma cases recurrent EP300-BCOR fusions were detected, which resulted in strong BCOR immunopositivity. We have therefore examined other, not analysed so far, types of central nervous system (CNS) tumours, pineoblastoma and germinoma, to assess a potential involvement of BCOR in these tumours. Levels of BCOR RNA expression were investigated by NanoString nCounter system analysis in a series of altogether 66 high grade paediatric tumours, including four pineoblastoma cases. Immunohistological detection of BCOR was performed in eight pineoblastoma, five germinoma and four atypical teratoid rhabdoid tumours (ATRTs), all located in the pineal region. We detected BCOR expression in all pineoblastomas, at the RNA and protein levels, but not in germinomas and ATRTs. Further analysis of pineoblastoma samples did not reveal the presence of either BCOR internal tandem duplication or BCOR fusion involvement. Positive immunohistological BCOR nuclear reaction in pineoblastoma may therefore differentiate this type of tumour from other high grade tumours located in the pineal region.

Chordoid gliomas of the third ventricle

Chordoid glioma is a rare slow-growing tumor of the central nervous system. Available world experience includes no more than 200 cases (lesion of the third ventricle in absolute majority of cases). Recognition and treatment of chordoid glioma are currently difficult problems due to small incidence of this disease. To describe clinical manifestations and surgical treatment of chordoid glioma of the third ventricle considering literature data and own experience. There were 12 patients (6 men and 6 women) with chordoid glioma between 2004 and 2023 (10 patients with lesion of the third ventricle, 1 - lateral ventricle, 1 - pineal region). Only patients with tumors of the third ventricle were analyzed. Total and subtotal resection was performed in 1 and 3 cases, respectively. Five patients underwent partial resection, 1 patient underwent biopsy. The follow-up data were available in 7 out of 10 patients (mean 25 months). Radiotherapy was performed in 4 patients (continued tumor growth in 2 cases). One patient died. Chordoid glioma is a benign tumor predominantly localized in the third ventricle. Preoperative MRI and CT in some cases make it possible to suspect chordoid glioma and differentiate this tumor from craniopharyngioma, meningioma and pituitary adenoma by such signs as isointense signal in T1WI, hyper- or isointense signal in T2WI, homogeneous contrast enhancement and edema of basal ganglia in T2 FLAIR images. The only effective treatment for chordoid glioma is surgery. Total resection is often impossible or extremely dangerous due to location of tumor, large size and invasion of the third ventricle. Postoperative mental disorders and diabetes insipidus, including severe hypernatremia, are common that requires mandatory monitoring of water and electrolyte balance.

A 2-step prediction model for diagnosis of germinomas in the pineal region.

Germinomas are sensitive to radiation and chemotherapy, and their management distinctly differs from other kinds of pineal region tumors. The aim of this study was to construct a prediction model based on clinical features and preoperative magnetic resonance (MR) manifestations to achieve noninvasive diagnosis of germinomas in pineal region. A total of 126 patients with pineal region tumors were enrolled, including 36 germinomas, 53 nongerminomatous germ cell tumors (NGGCTs), and 37 pineal parenchymal tumors (PPTs). They were divided into a training cohort (n = 90) and a validation cohort (n = 36). Features were extracted from clinical records and conventional MR images. Multivariate analysis was performed to screen for independent predictors to differentiate germ cell tumors (GCTs) and PPTs, germinomas, and NGGCTs, respectively. From this, a 2-step nomogram model was established, with model 1 for discriminating GCTs from PPTs and model 2 for identifying germinomas in GCTs. The model was tested in a validation cohort. Both model 1 and model 2 yielded good predictive efficacy, with c-indexes of 0.967 and 0.896 for the diagnosis of GCT and germinoma, respectively. Calibration curve, decision curve, and clinical impact curve analysis further confirmed their predictive accuracy and clinical usefulness. The validation cohort achieved areas under the receiver operating curves of 0.885 and 0.926, respectively. The 2-step model in this study can noninvasively differentiate GCTs from PPTs and further identify germinomas, thus holding potential to facilitate treatment decision-making for pineal region tumors.

Pediatric Pineal Region Tumors: Special Reference to Posterior Interhemispheric Trans-Tentorial Approach.

Pediatric pineal region tumors consist of tumors of pineal gland origin and parapineal origin. The former are comprised of germ cell tumor (GCT) and pineal parenchymal tumor. The latter originate from the surrounding neural structures, such as the midbrain and thalamus; thus, they are often benign gliomas during childhood. Pineal region tumors often cause obstructive hydrocephalus, which is the main cause of presenting symptoms. Advanced imaging discloses precise location and extension of the tumor and associated anomalies such as hydrocephalous, dissemination, hemorrhage, etc. Hydrocephalus has been managed with CSF diversion, mostly using an endoscopic third ventriculostomy. Because of different treatment paradigms for each tumor type, histological confirmation is needed either through biopsy, tumor markers for GCTs, and/or surgical resection sampling. Radical resection of these tumors remains a challenge due to their deep-seated location and involvement of delicate neural and vascular structures. Comparison of common craniotomy approaches, occipital transtentorial (OT) and infratentorial supracerebellar (ITSC), is reviewed for their advantages and disadvantages. Surgical area exposure and blind spots are important factors for successful tumor removal. The surgical techniques and nuances that the author employs for tumor resection via a posterior interhemispheric transtentorial approach are presented.

The role of endoscopic perforation of the third ventricular floor in the treatment of pineal neoplasms. One solution for different approaches to the treatment of pineal tumors

Neoplasms of the pineal region include an extensive list of pathological formations, which represent one of the most difficult areas for surgical treatment. The resolution of hydrocephalus in pineal tumors is one of the most important tasks in the treatment of tumors of this localization. In the presented work, we report on an alternative surgical strategy for the management of certain patients with pineal neoplasms, which allows treating the symptomatic manifestation of hydrocephalus by endoscopic third ventriculostomy and further conducting specific therapy or observing pathological formation in the pineal region and the posterior parts of the third ventricle.

Differentiation between germinoma and other pineal region tumors using diffusion-and susceptibility-weighted MRI

PurposeTo evaluate the effectiveness of diffusion-weighted imaging (DWI) and susceptibility-weighted imaging (SWI) for differentiation between germinoma and other pineal region tumors. MethodThis retrospective study consisted of 72 patients with pathologically proven pineal region tumors between January 2010 and August 2020. Tumors were classified as germinomas (40), non-germinomatous germ cell tumors (11) (NGGCT), pineal parenchymal tumors (10) (PPT), and other types of tumors (11). Visual scale score, ADC values and SWI intratumoral susceptibility signal (ITSS) score were analyzed and compared to histopathology data. ResultsThe mean apparent diffusion coefficient (ADCmean) and minimum apparent diffusion coefficient (ADCmin) ratio of germinoma were significantly lower than NGGCT. ADCmean or ADCmin cut-off ratio of ≤ 1.48 or ≤ 1.32 allowed for discrimination between germinoma and NGGCT with sensitivity and specificity of 100 % and 63.6 %. An ADCmin cut-off ratio of ≥ 0.93 allowed for discrimination between germinoma and PPT with sensitivity and specificity of 60 % and 80.0 %. ADCmin cut-off ratio of ≤ 1.15 allowed for discrimination of germinoma from other types of tumors with sensitivity and specificity of 87.5 % and 54.5 %. ConclusionsADC ratio can differentiate germinoma from other types of pineal region tumors. Our initial results suggest that ITSS score was not significantly correlated with specific histology subtype.

Surgical outcome of pineal region lesions in paediatric population

Introduction. Pineal region pathologies are heterogenous, spectrum ranging from benign, infective to malignant in nature such as parenchymal, germ cell, glial, melanomas, metastatic, tubercular, etc. These lesions are commoner in the pediatric age group and have a variable outcome. The goal of this study is to present our experience regarding the surgical outcomes of pineal region lesions in the paediatric population. Objective. The objective of this study is to access the surgical outcome of pineal region lesions in the paediatric population Methods and Material. Eighty cases of pineal region lesions in the paediatric population (upto 15 years of age) operated in the neurosurgery department, G.B Pant Hospital New Delhi via either Occipital transtentorial or Supracerebellar Infratentorial approaches were retrospectively analyzed. Results. There were four main groups of lesions with pineal parenchymal tumours (35 cases) being the commonest. Glial tumours were the next most common contributing 29 cases. Germ cell tumours comprise 7 and miscellaneous 9 cases. The outcome showed graded improvement with the extent of tumour removal and 57 patients(71.25%) improved following surgery. The clinical status of 20 patients(25%) remained unchanged and 3(3.75%) deteriorated from their pre-operative status. 3 patients(3.75%) died in the immediate post-operative period and 11(13.75%) died due to recurrent disease. Conclusion. A graded increase in survival was noted with increasing the degree of resection and postoperative adjuvant therapy in malignant pineal tumours whereas benign pineal lesions can be managed with surgery. Pure germinomas are the only tumour for which the survival rate was unrelated to extent of tumour resection.

MPC-16 CHARACTERISTICS AND PROGNOSTIC FACTORS OF H3K27M-MUTANT DIFFUSE MIDLINE GLIOMA

Abstract H3 K27M-mutant diffuse midline gliomas (DMG) is a still challenging disease with no effective medical therapies. We analyzed the characteristics and prognostic factors of 64 patients with midline gliomas including 18 patients with H3 K27M-mutant DMG treated in Kobe University Hospital from 2006 to 2021. The median age at diagnosis in midline gliomas was 50.1 years (range: 14-82 y). All tumors were located in thalamus n=25, corpus callosum n=8, brainstem n=8, spinal cord n=6, cerebellum n=15, and pineal region n=2. Isocitrate dehydrogenase 1 (IDH1) and H3 K27 mutation was recognized in 6 and 18 patients, respectively, which was mutually exclusive. In all midline gliomas, the identification of an H3 K27M mutation was significantly a poor prognosis factor (median 19.8 months vs 27.9 months, p=0.042). Compared to midline gliomas without histone H3 and IDH1 mutations (IDH1/H3 wild type), however, H3 K27M-mutant DMG had no worse overall survival (median 19.8 months vs 15.9 months, p=0.51). H3 K27M-mutant DMG is considered as a distinct WHO Grade 4 regardless of histological features, but the biological properties of H3 K27M mutation is not yet defined in IDH1 wild-type midline gliomas.

A comprehensive machine-learning model applied to MRI to classify germinomas of the pineal region

BackgroundPineal region tumors (PRTs) are highly histologically heterogeneous. Germinoma is the most common PRT and is treatable with radiotherapy and chemotherapy. A non-invasive system that helps identify germinoma in the pineal region could reduce lab exams and traumatic therapies. MethodsIn this retrospective study, 122 patients with histologically confirmed PRTs and pre-operative multi-modal MR images were included. Radiomics features were extracted from different ROIs and image sequences separately. A computational framework that combines a few classification and feature selection algorithms were used to predict histology with radiomics features and demographics. We systemically benchmarked performance of models with feature matrices from all possible combinations of ROIs and image sequences. The Area under the ROC Curve (AUC) was then used to evaluate model performance. ResultsModels with demographics and radiomics features outperform radiomics-only or demographics-only models. The best demographical-radiomics model reached the highest AUC of 0.88 (CI95%: 0.81–0.96). Through the comprehensive evaluation of possible sequence combinations in the differential diagnosis of pineal tumor, T1 and T2 emerged as the most informative sequences for the task. There is imbalanced usage of feature classes as we analyze their proportion in all models. ConclusionsThe demographical-radiomics model can accurately and efficiently identify germinomas in the pineal region. The preference for MRI sequences, radiomics feature classes, features selection and classification algorithms provide a valuable reference for future attempts at developing classifiers on medical images.

Pure endoscopic resection of pineal region tumors through supracerebellar infratentorial approach with ‘head-up’ park-bench position

ABSTRACT Objective Neuroendoscopic resection via supracerebellar infratentorial (SCIT) approach is adequate for some indicated pineal region tumors with the natural infratentorial corridor. We described this full endoscopic approach through a modified ‘head-up’ park-bench position to facilitate the procedure. Methods We reviewed the clinical and radiological data of four patients with pineal region lesions who underwent pure endoscopic tumor resection through the SCIT approach with this modified position. The related literature concerning fully endoscopic pineal region tumor resection was also reviewed. Results This cohort included four patients with pineal region tumors. External ventricular drainage (Ommaya reservoir) was performed in three patients with hydrocephalus in advance. The average tumor volume was 19.2 ± 17.2 cm3. Pathological examination confirmed two mixed germinomas, one glioblastoma multiforme, and one hemangioblastoma. Gross total resection (GTR) was achieved in all patients, and all patients recovered well without neurological deficits or surgical complications. Hydrocephalus was relieved among all patients. Conclusions The pure endoscopic SCIT approach could enable safe and effective resection of pineal region tumors, even for relatively large lesions. The endoscope could provide a panoramic view and illumination of the deep-seated structures. Compared with the sitting position, this modified ergonomic position could be implemented easily.

Occipital interhemispheric transtentorial approach in pediatric patients for lesions of the superomedial cerebellum: operative findings and results.

The occipital interhemispheric transtentorial (OITT) approach is frequently used for accessing the pineal region. There are scarce reports of using the OITT to access superior cerebellar lesions. This approach affords the patient several advantages over traditional posterior fossa approaches. This study is to describe and evaluate clinical outcomes in a single surgeon case series of the OITT approach for pediatric patients with lesions of the superior cerebellum. All pediatric patients who underwent an OITT craniotomy for a superior cerebellar lesion by a single surgeon over a 5-year period were included in this retrospective analysis. Patient demographics and clinical data were collected. Thirteen pediatric patients were identified. Cases included twelve tumors and one arteriovenous malformation. Gross total resection was achieved in 92% of cases. No patients developed posterior fossa syndrome. Two patients had transient homonymous hemianopsia that resolved by 1month post-operatively. There were no permanent neurological deficits. For superomedial cerebellar lesions presenting to the tentorial surface of the superior cerebellum in patients with normal to steep tentorial angles, the OITT approach is effective and safe. This approach has a low risk of posterior fossa syndrome and permanent visual deficits when applied appropriately. Patient selection is critical for maximizing the advantages of the OITT for superior cerebellar lesions.