Alternatives approaches to the sub-occipital transtentorial route for pineal tumors: How and when I do it?

Pineal Tumor Surgery-The Choice of the Approach Related to Tumor Characteristics and Posterior Fossa Anatomy

OBJECTIVE

This research aimed to determine whether an adequate surgical approach can be chosen based on clearly defined values of anatomical landmarks (tentorial angle) and tumor size and extension.

METHODS

We conducted a retrospective analysis of patients operated on because of pineal tumors. The cohort was divided depending on the surgical approach. On preoperative magnetic resonance imaging, we measured maximal diameters, tumor volume, and tumor propagation. In the group of patients operated with the supracerebellar infratentorial approach, we also tested the correlation of tentorial angle with residual tumor. Differences among groups in resection, complications rate, and outcome were tested by the χ2 test. Finally, in both groups, the correlation of residual tumor with tumor volume, propagation, and diameters was tested using the receiver operating characteristic curve.

RESULTS

In the group operated with a supracerebellar approach, total resection was achieved in 78% of the patients. The critical value of cranio-caudal diameter correlated with tumor residue was 31 mm, for lateral-lateral diameter 25 mm, for the lateral extension 14 mm, and tumor volume 12 cm3. Tentorial angle did not influence the extent of the resection. In the group operated with an occipital transtentorial approach, the critical tumor volume related to tumor residue was 9 mm3, anterior-posterior diameter 29 mm, and cranio-caudal diameter 28 mm. The extent of the resection was significantly higher in the supracerebellar group.

CONCLUSIONS

In both approaches, tumors larger than 3 cm show an increased risk of subtotal resection. Except when most tumor volume is localized above the venous system, we advocate a supracerebellar corridor as an effective approach that is not limited by tentorial angle.

Lateral Temporal Approach for Image-Guided Stereotactic Biopsy of Pineal Region Tumors

BACKGROUND

Biopsy of pineal region neoplasms is frequently accomplished by way of endoscopic transventricular access or using an image-guided, computer-assisted stereotactic approach.

METHODS

We evaluated a nonorthogonal lateral temporal approach for stereotactic biopsy of pineal region tumors as a variation of previously described stereotactic methods. Magnetic resonance imaging-guided frameless stereotaxy was used to plan and perform biopsies of pineal region tumors using a nonorthogonal trajectory extending from the superior or middle temporal gyri through the temporal stem, anterior to the atrium of the lateral ventricle, and posterior to the corticospinal tract.

RESULTS

All patients had an uncomplicated postoperative course and remained at neurologic baseline. No parenchymal or ventricular hemorrhage was present on postoperative scans. A tissue diagnosis was obtained in all patients.

CONCLUSIONS

This method appears to be a safe alternative to stereotactic biopsy using other trajectories and provides adequate tissue for definitive diagnosis.

Anatomic, qualitative, and quantitative evaluation of the variants of the infratentorial supracerebellar approach to the posteroinferior thalamus

The posteroinferior region of the thalamus is formed by the pulvinar, and it is surgically accessed through the infratentorial supracerebellar approach, between the midline and the retromastoid region. This study aimed to compare the paramedian, lateral, extreme lateral, and contralateral paramedian corridors with the posteroinferior thalamus through a suboccipital craniotomy and an infratentorial supracerebellar access. Ten cadavers were studied, and the microsurgical dissections were accompanied by the measurement of the variables using a neuronavigation system. Statistical analysis was performed using analysis of variance (ANOVA). The distance between the access midpoint at the cranial surface and pulvinar varied between 53.3 and 53.9 mm, the contralateral access being an exception (59.9 mm). The vertical angle ranged from 20.6° in the contralateral access to 23.5° in the lateral access. There was a gradual increase in the horizontal angle between the paramedian (17.4°), lateral (31.3°), and extreme lateral (43.7°) accesses. But, this angle in the contralateral access was 14.6°, similar to that of the paramedian access. The exposed area of the thalamus was 125.1 mm² in the paramedian access, 141.8 mm² in the lateral access, and 165.9 mm² in the extreme lateral access, which was similar to that of the contralateral access (164.9 mm²). The horizontal view angle increased with lateralization of the access, which facilitated microscopic visualization. With regard to the exposure of the microsurgical anatomy, the extreme lateral and contralateral accesses circumvent the neural and vascular obstacles at the midline, allowing a larger area of anatomical exposure.

Intravascular Papillary Endothelial Hyperplasia of the Pineal Region: A Case Report and Review of the Literature

BACKGROUND

Intravascular papillary endothelial hyperplasia (IPEH) is a benign vascular lesion that is uncommon in the central nervous system. To our knowledge, there has been only one previous report of occurrence in the pineal region. We present a second case and a review of the literature.

CASE DESCRIPTION

A 28-year-old woman presented with 1 month of headaches and visual auras. Brain magnetic resonance imaging scan demonstrated a 2.6- × 1.8- × 1.3-cm nonenhancing T1-hypointense, T2-/fluid-attenuated inversion recovery-hyperintense pineal region mass with cerebral aqueduct obstruction and hydrocephalus. She underwent placement of a right extraventricular drain followed by complete surgical resection. Histologic analysis was consistent with IPEH.

CONCLUSIONS

Although rare, IPEH is an entity that should be considered in the differential diagnosis for intracranial masses with radiographic features characteristic of vascular lesions. Tissue sampling is imperative for distinction from more malignant entities. Complete resection is curative and is the standard of care when feasible. Given the risk of local progression and neurologic compromise with subtotal resection of central nervous system lesions, further study regarding adjuvant treatment options is warranted.