The use of exoscope combined with tubular retractor system for minimally invasive transsulcal resection of an ventricular atrium atypical choroid plexus papilloma: Three-dimensional operative video

Background:

Choroid plexus papilloma represents 1–4% of pediatric brain tumors, mostly located in the ventricular atrium.[1] Intraventricular tumors represent a challenge due to the poor visualization of the surgical field and damage to surrounding structures.[2] Use of tubular retraction reduces cerebrovascular trauma to the surrounding parenchyma by distributing pressure uniformly, allowing less invasive corticotomy, and more stability on surgical corridors that allow the surgeon to use both hands and external visualization devices.[2-5]

Case Description:

We present the case of a 3-year-old boy with progressive headache, vomiting, and loss of control in the left hand for 3 months, with a history of ventricular shunt placement for acute obstructive hydrocephalus. The MRI revealed large lobulated lesion, which was hypointense on T1, hyperintense on T2, marked enhancement on T1 C+ (Gd) within the atrium of the right lateral ventricle, and spectroscopy with a peak of choline. Written consent for the use of photos and videos on this work was obtained from the patient’s mother. A high-definition two-dimensional exoscope (VITOM^® Karl Storz, Tuttlingen) was used during the surgical approach and throughout tumor removal, which was aided by ViewSite Brain Access System (VBAS^®; Vycor Medical Inc.).[3] We performed a transparietal minimally invasive transsulcal parafascicular approach through the Frazier point for direct access to the ventricular atrium. Histological examination confirmed atypical choroid plexus papilloma. Postoperative imaging shows no residual tumor. The postoperative course was satisfactory with improvement of the headache and control of the left hand, leading to discharge home 1 week after surgery.

Conclusion:

The tubular transparietal minimally invasive approach obviates the need for traditional approaches to the atrium. This technique is safe and effective for the treatment of intraventricular and periventricular lesions, thus making this challenging target in more accessible to neurosurgeons, avoiding structure damage and any associated morbidity or mortality.

The anterior incisural width as a preoperative indicator for intradural space evaluation: An anatomical investigation

Background:

The opticocarotid triangle (OCT) and the carotico-oculomotor triangle (COT) are two anatomical triangles used in accessing the interpeduncular region. Our objective is to evaluate if the anterior incisural width (AIW) is an indicator to predict the intraoperative exposure through both triangles.

Methods:

Twenty sides of 10 cadaveric heads were dissected and analyzed. The heads were divided into the following: Group A – narrow anterior incisura and Group B – wide anterior incisura – using 26.6 mm as a cutoff distance of the AIW. Subsequently, the area of the COT and the OCT in the transsylvian approach was measured, along with the maximum widths through the two trajectories in modified superior transcavernous approach.

Results:

The COT in the wide group was shown to have a significantly larger area compared with the COT in the narrow group (38.4 ± 12.64 vs. 58.3 ± 15.72 mm, P < 0.01). No difference between the two groups was reported in terms of the area of the OCT (50.9 ± 19.22 mm vs. 63.5 ± 15.53 mm, P = 0.20), the maximum width of the OCT (6.6 ± 1.89 vs. 6.5 ± 1.38 mm, P = 1.00), or the maximum width of the COT (11.7 ± 2.06 vs. 12.2 ± 2.32 mm, P = 0.50). Clinical cases were included.

Conclusion:

An AIW <26.6 mm is an unfavorable factor related to a limited COT area in a transsylvian approach for pathologies at the interpeduncular fossa. Preoperative identification and measurement of a narrow AIW can suggest the need to add a transcavernous approach.

High flow bypass for right giant cavernous internal carotid artery aneurysm with fibromuscular dysplasia of cervical internal carotid artery: microsurgical 2-D video

Background

It is well known that intracranial aneurysms can be associated to fibromuscular dysplasia (FMD). Nevertheless, it is not clear the best treatment strategy when there is an association of giant symptomatic cavernous carotid aneurysm with extensive cervical internal carotid artery (ICA) FMD.

Case Description

We present the case of 63 year-old right-handed female with hypothyroidism, 1 month history of right-sided pulsatile headache and visual disturbances with feeling of fullness sensation and blurry vision. Her neurological exam showed partial right oculomotor nerve palsy with mild ptosis, asymmetric pupils (right 5 mm and left 3mm, both reactive), and mild exotropia, normal visual acuity. Computed tomography angiogram and conventional angiogram showed 2.5 × 2.6 × 2.6 cm non-ruptured aneurysm arising from cavernous segment of the right ICA. She had right hypoplastic posterior communicant artery, and collateral flow through anterior communicant artery during balloon test occlusion and the presence of right cervical ICA FMD. The patient was started on aspirin. After lengthy discussion of treatment options in our neurovascular department, between observations, endovascular treatment with flow diverter device, or high flow bypass, recommendation was to perform high flow bypass and patient consented for the procedure. We performed right-sided pterional trans-sylvian microsurgical approach and right neck dissection at common carotid bifurcation under electrophysiology monitoring (somatosensory evoked potentials and electroencephalography); while vascular surgery department assisted with the radial artery graft harvesting. The radial artery graft was passed through preauricular tunnel, cranially was anastomosed at superior trunk of middle cerebral artery, and caudally at external carotid artery (Video). Intraoperative angiogram showed adequate bypass patency and lack of flow within aneurysm. The patient was extubated postoperatively and discharged home with aspirin in postoperative day 5. Improvement on oculomotor deficit was complete 3 weeks after surgery.

Conclusion

Nowadays, endovascular therapy can manage small to large cavernous ICA aneurysms even if associated to FMD, although giant symptomatic cavernous carotid aneurysms impose a different challenge. Here, we present the management for the association of symptomatic giant cavernous ICA aneurysm and cervical ICA FMD with high flow bypass. We consider important to keep the skills in the cerebrovascular neurosurgeon armamentarium for the safe management of these lesions.

Combined petrosal approach for resection of petroclival chondrosarcoma: Microsurgical 2-D video

Background:

Petroclival lesions pose a significant neurosurgical challenge due to involvement or close proximity to important neurovascular structures. Chondrosarcomas are rare lesions that can affect these areas.

Case Description:

A 24-year-old male with 3 months history of poor coordination, imbalance, left-sided face hypoesthesia, facial palsy House-Brackmann Grade 2, and 6^th cranial nerve palsy with diplopia. Hearing was preserved. Preoperative images showed a 5.5 cm multilobulated enhancing extra-axial mass centered in the left petroclival region with extension into middle and posterior fossa causing severe (Stage 3) brainstem compression.^[1] After a lengthy discussion of treatment options, the patient consented for the procedure. We performed a presigmoid retrolabyrinthine combined petrosal approach. We used cranial nerves monitoring (VII, VIII, IX, X, XI, XII), frameless stereotaxy, and a lumbar drain. Due to the tumor size and location (petroclival region with extension into the posterior and middle cranial fossa), we chose this approach to achieve a maximal safe resection of the tumor and preserve hearing. Alternative approaches of use are expanded middle fossa with transcavernous extension or expanded endonasal approach. The selected approach achieved wide exposure of the tumor which was highly vascular. The tumor was carefully dissected off the brainstem, cranial nerves (IV, V, VI, VII, VIII), and basilar artery trunk. A gross total resection was achieved (Multimedia 1). The patient did well after surgery and was extubated on postoperative day (POD) 1 and the lumbar drain removed on POD 5. Pathology reported low-grade chondrosarcoma (WHO grade I). At 3 months follow-up, the patient improved neurologically, including facial nerve weakness (House-Brackmann Grade 1) except for his left 6^th cranial nerve palsy which mildly improved.

Conclusion:

Petroclival chondrosarcomas are rare tumors that are usually treated with surgical resection followed by stereotactic radiosurgery. The tumor size, location, and extension dictate approach selection. For lesions involving the petroclival region with extension into the middle fossa and posterior fossa, the combined petrosal approach is reasonable.

Retractorless interhemispheric transtentorial approach for large lesions in the posterior incisural space

Background:

Surgical resection of lesions in the posterior incisural space presents a significant surgical challenge, which may result in postoperative visual complications and other neurological deficits. We, therefore, describe a retractorless interhemispheric transtentorial approach that avoids surrounding brain structures with positive outcomes and no complications or visual damage.

Case Description:

We present four cases of lesions in the posterior incisural space that was treated with a retractorless interhemispheric transtentorial approach. Two patients were previously seen at another institution for a falcotentorial meningioma. We resected the meningiomas with a parietal-occipital interhemispheric transtentorial approach with no neurological deficits. A third patient presented with a large superior vermian hemangioblastoma with a steep angle of the tentorium. The fourth patient had a large upper vermian metastatic lesion with progressive enlargement, which was refractory to radiation treatments and chemotherapy, and we achieved partial resection. Postoperative visual function was completely preserved in all patients.

Conclusion:

A carefully executed retractorless interhemispheric approach in select cases is an effective option to reduce morbidity and prevent visual complications when removing lesions in the posterior tentorial incisure.

Microsurgical Technique for Basilar Apex Aneurysm Clipping: Two-Dimensional Video

We present the case of a 57-year-old female with hypertension, current smoker status, and recent headaches. Imaging studies showed an unruptured 8-mm basilar apex wide neck aneurysm located 4 mm above posterior clinoid (Figure 1) with a 3-mm anterior communicant artery aneurysm. No contraindications were encountered for endovascular treatment, although after we evaluated endovascular and surgical options, surgical clipping was considered also a safe and favorable option based on anterior projection of aneurysm, height of the basilar artery bifurcation, small and elongated posterior communicant artery, and available space between posterior clinoid and basilar artery (4 mm). The presence of a second aneurysm increased the patient's interest in a more definitive treatment, as we mentioned the possibility of its treatment if considered safe intraoperatively. A cranio-orbito-zygomatic craniotomy, anterior clinoidectomy, and sylvian fissure dissection was performed with electrophysiology monitoring. The exposure was enhanced by sphenoparietal sinus ligation, and the anterior clinoidectomy allowed working spaces at optic-carotid and carotid-oculomotor spaces for Liliequist membrane dissection, without need for posterior clinoid removal (Figure 2). Brief temporary clipping at basilar trunk below superior cerebellar arteries at perforating free zone was performed. Two clips were applied, obliterating adequately the aneurysm respecting perforating vessels. After the basilar apex aneurysm clipping, we proceeded in a standard fashion to clip the additional anterior communicant artery aneurysm. Micro-Doppler and intraoperative angiogram confirmed aneurysm exclusion and patent parent vessels (Video 1). The patient developed minimal ptosis due to partial right oculomotor nerve palsy that recovered completely in 2 weeks; otherwise, her neurologic exam was normal. At 1-year follow up, computed tomography angiography showed complete aneurysm exclusion.