True aqueductal tumors: a unique entity

Clinical, histopathological and molecular risk factors for recurrence of pilocytic astrocytomas: brainstem/spinal location, nestin expression and gain of 7q and 19 are associated with early tumor recurrence

Pilocytic astrocytomas (PAs) are benign tumors. However, clinically aggressive PAs despite benign histology have been reported, and histological and molecular risk factors for prognosis have not been elucidated. 38 PAs were studied for clinical, histological, and molecular factors, including tumor location, extent of resection, post-operative treatment, glioma-associated molecules (IDH1/2, ATRX, BRAF, FGFR1, PIK3CA, H3F3A, p53, VEGF, Nestin, PD-1/PD-L1), CDKN2A/B deletion, and chromosomal number aberrations, to see if there is any correlation with patient's progression-free survival (PFS). Brainstem/spinal location, extent of resection and post-operative treatment, and VEGF-A, Nestin and PD-L1 expression, copy number gain of chromosome 7q or 19, TP53 mutation were significantly associated with shorter PFS. None of the histological parameters was associated with PFS. Multivariate analyses demonstrated that high Nestin expression, gain of 7q or 19, and extent of removal were independently predictive for early tumor recurrence. The brainstem/spinal PAs appeared distinct from those in the other sites in terms of molecular characteristics. Clinically aggressive PAs despite benign histology exhibited high Nestin expression. Brainstem/spinal location, extent of resection and some molecular factors including Nestin expression and gains of 7q and 19, rather than histological parameters, may be associated with early tumor recurrence in PAs.

Endoscopic excision of an aqueduct of Sylvius cavernoma causing obstructive hydrocephalus: technical note

BACKGROUND AND IMPORTANCE

Acquired lesions within the aqueduct of Sylvius are rare and their surgical management is challenging. Open transcranial approaches require dissection and manipulation of surrounding eloquent structures. Use of an endoscope can avoid potential morbidity from traversing and handling eloquent structures during open approaches whilst providing better visualisation of an intraventricular lesion.

CLINICAL PRESENTATION

A 62-year-old female presented with insidious onset short-term memory loss, unsteady gait, urinary incontinence and left-sided dysaesthesia. Magnetic resonance imaging (MRI) revealed hydrocephalus from an obstructive haemorrhagic lesion consistent with a cavernoma at the central midbrain within the aqueduct of Sylvius. An endoscopic approach was selected to provide optimal visualisation of the lesion. As only a single instrument could be accommodated, rotational movements were employed to tease out the lesion. Gross total resection was achieved. Her symptoms improved immediately postoperatively and she made a complete recovery by 2 months. Post-operative MRI showed resolution of hydrocephalus and no evidence of residual/recurrence of the lesion. Unfortunately, she developed hydrocephalus 3 months post-op and required placement of a ventriculoperitoneal shunt.

CONCLUSIONS

Endoscopic resection is safe and feasible for selected periaqueductal lesions as it provides direct access while minimising disruption of the surrounding anatomical structures. The limitation of only having a single instrument can be overcome by employing rotational movements.

Endoscopic Third Ventriculostomy - A Review

BACKGROUND

Endoscopic third ventriculostomy (ETV) has become a proven modality for treating obstructive and selected cases of communicating hydrocephalus.

OBJECTIVE

This review aims to summarize the indications, preoperative workup, surgical technique, results, postoperative care, complications, advantages, and limitations of an ETV.

MATERIALS AND METHODS

A thorough review of PubMed and Google Scholar was performed. This review is based on the relevant articles and authors' experience.

RESULTS

ETV is indicated in obstructive hydrocephalus and selected cases of communicating hydrocephalus. Studying preoperative imaging is critical, and a detailed assessment of interthalamic adhesions, the thickness of floor, arteries or membranes below the third ventricle floor, and prepontine cistern width is essential. Blunt perforation in a thin floor, while bipolar cautery at low settings and water jet dissection are preferred in a thick floor. The appearance of stoma pulsations and intraoperative ventriculostomography reassure stoma and basal cistern patency. The intraoperative decision for shunt, external ventricular drainage, or Ommaya reservoir can be taken. Magnetic resonance ventriculography and cine phase-contrast magnetic resonance imaging can determine stoma patency. Good postoperative care with repeated cerebrospinal fluid drainage enhances outcomes in selected cases. Though the complications mostly occur in an early postoperative phase, delayed lethal ones may happen. Watching live surgeries, assisting expert surgeons, and practicing on cadavers and models can shorten the learning curve.

CONCLUSION

ETV is an excellent technique for managing obstructive and selected cases of communicating hydrocephalus. Good case selection, methodical technique, and proper training under experts are vital.

Management strategies for pediatric patients with tectal gliomas: a systematic review

Pediatric tectal gliomas generally have a benign clinical course with the majority of these observed radiologically. However, patients often need treatment for obstructive hydrocephalus and occasionally require cytotoxic therapy. Given the lack of level I data, there is a need to further characterize management strategies for these rare tumors. We have therefore performed the first systematic review comparing various management strategies. The literature was systematically searched from January 1, 2000, to July 30, 2020, to identify studies reporting treatment strategies for pediatric tectal gliomas. The systematic review included 355 patients from 14 studies. Abnormal ocular findings-including gaze palsies, papilledema, diplopia, and visual field changes-were a common presentation with between 13.6 and 88.9% of patients experiencing such findings. CSF diversion was the most performed procedure, occurring in 317 patients (89.3%). In individual studies, use of CSF diversion ranged from 73.1 to 100.0%. For management options, 232 patients were radiologically monitored (65.4%), 69 received resection (19.4%), 30 received radiotherapy (8.4%), and 19 received chemotherapy (5.4%). When examining frequencies within individual studies, chemotherapy ranged from 2.5 to 29.6% and radiotherapy ranged from 2.5 to 28.6%. Resection was the most variable treatment option between individual studies, ranging from 2.3 to 100.0%. Most tectal gliomas in the pediatric population can be observed through radiographic surveillance and CSF diversion. Other forms of management (i.e., chemotherapy and radiotherapy) are warranted for more aggressive tumors demonstrating radiological progression. Surgical resection should be reserved for large tumors and/or those that are refractory to other treatment modalities.

The extreme anterior interhemispheric transcallosal approach for pure aqueduct tumors: surgical technique and case series

Purely aqueductal tumors represent a rare but distinct entity of neoplasms with characteristic morphology and clinical presentation. This study aims to describe the extreme anterior interhemispheric transcallosal approach as a surgical option for purely aqueductal tumors in the upper part of the cerebral aqueduct and present the surgical results. Prospectively collected data of 4 patients undergoing the extreme anterior interhemispheric transcallosal approach for purely aqueductal tumors in the upper cerebral aqueduct was analyzed. The technique is a variation of the anterior interhemispheric transcallosal approach. The callosotomy is placed at the transition between the body and genu of the corpus callosum, allowing an approach steep enough to reach through the foramen of Monro to the upper cerebral aqueduct without opening the choroidal fissure. All patients had preoperative, and intraoperative or immediate postoperative 3-T magnetic resonance imaging, and underwent examination at admission, after surgery, at discharge, and 3 months postoperatively. Patient data are reported according to common descriptive statistics. All patients harbored low-grade gliomas causing hydrocephalus. Complete resection was achieved without mortality or morbidity. All patients recovered and presented neurologically intact at the 3-month postoperative follow-up. None had recurrence or needed adjuvant therapy. The extreme anterior interhemispheric transcallosal approach proved to be effective and safe. This approach does not require manipulation of the choroidal fissure or disrupt healthy brain parenchyma (except for a small callosotomy). We propose it as an option for removing a purely aqueductal tumor in the upper cerebral aqueduct with associated hydrocephalus.

Pineal region tumors: an entity with crucial anatomical nuances

PURPOSE

Intra-axial "pineal region" tumors include pineal, tectal, and aqueductal tumors. All three tumor subgroups cause obstruction of the aqueduct; however, they differ in radiological nuances, pathology, differential diagnosis, and treatment. The goal of this manuscript is to describe the radiological, clinical, and pathological nuances that differentiate between these subgroups.

METHODS

All patients with intra-axial pineal region tumors were analyzed retrospectively, including demographics, radiological characteristics, pathology, treatment, and outcome.

RESULTS

Forty-nine patients (1-69 years of age) were included: 19 pineal, 10 tectal, 10 aqueductal, 4 periaqueductal, and 6 complex. The 3 main subgroups differed in various radiological and anatomical nuances. Age and gender did not differ between groups. Other factors that did not differ between groups included T1 and T2 signals, presence of blood products, a normally located (non-displaced) tectum, anterior tectal displacement, thalamic involvement, and presence of hydrocephalus. The pathological spectrum differed between the 3 main subgroups, as well as the surgical treatment, and outcome.

CONCLUSIONS

Despite sharing a close anatomical location, as well as all causing obstruction of the aqueduct with secondary hydrocephalus, the differential diagnosis, diagnostic methods, and possible treatment and surgical options differ between the various subgroups. Anatomical nuances are described to better delineate the various tumor subgroups and recommend specific treatment approaches.

MRI-based diagnosis and treatment of pediatric brain tumors: is tissue sample always needed?

Traditional management of newly diagnosed pediatric brain tumors (PBTs) consists of cranial imaging, typically magnetic resonance imaging (MRI), and is frequently followed by tissue diagnosis, through either surgical biopsy or tumor resection. Therapy regimes are typically dependent on histological diagnosis. To date, many treatment regimens are based on molecular biology. The scope of this article is to discuss the role of diagnosis and further treatment of PBTs based solely on MRI features, in light of the latest treatment protocols. Typical MRI findings and indications for surgical biopsy of these lesions are described.

Hemangioblastoma of Cerebral Aqueduct Removed via Sitting, Supracerebellar Intracollicular Approach

BACKGROUND

Tumors protruding into the cerebral aqueduct are rare, and tumors arising from within the cerebral aqueduct are rarer still.

CASE DESCRIPTION

In this report, we discuss the presentation and clinical outcome of a 65-year-old man who presented to us with symptoms of hydrocephalus. Prior imaging had revealed a small enhancing nodule within the cerebral aqueduct. In the 6 months between initial imaging and our seeing the patient, the tumor demonstrated substantial interval growth, so the patient was offered resection. The tumor was accessed using a sitting, supracerebellar, intracollicular approach, which allowed for gross total resection of the mass without complication. Histopathology later revealed the lesion to be a hemangioblastoma. Two years after surgery, the patient was doing well with no neurologic deficits.

CONCLUSIONS

We report the first case of an aqueductal hemangioblastoma and describe our use of a sitting, supracerebellar, intracollicular approach to access tumors occupying this cerebrospinal fluid space.

Diagnosis and treatment for pure aqueductal tumor

Pure aqueductal tumor (PAT) typically originates from pure aqueductal region and is extremely rare. It is radiographically similar to tectal glioma. We examined two patients with PATs who were diagnosed with pilocytic astrocytoma and rosette-forming glioneuronal tumor. Both cases showed a progressive clinical course. It is important to distinguish between PAT and tectal glioma by radiographic imaging because the treatment strategy is different. While observation is common for tectal gliomas, a biopsy is recommended at the same time of endoscopic third ventriculostomy for PAT with hydrocephalus. Low-grade PATs show an aggressive clinical course in some cases. Our two cases also showed aggressive course in spite of no genetic aggressive mutations. Sagittal view by constructive interference in steady state (CISS) imaging was helpful to make an accurate diagnosis of PAT. Close observation is needed if PAT is diagnosed as low-grade tumor.