Microsurgical Treatment for a Ruptured Posterior Inferior Cerebellar Artery Aneurysm: A 3-Dimensional Surgical Video and Anatomic Landmarks Review

Aneurysms are the most frequent issue for the posterior inferior cerebellar artery (PICA). PICA aneurysms account for 1.4% to 4.5% of all intracranial aneurysms.^1-3 Although the majority of PICA aneurysms arise from their junction with the vertebral artery, they can be found in any of 5 segments.^4,5 Although PICA is more prone to form nonsaccular aneurysms than other intracranial arteries, ruptured aneurysms are usually saccular.⁶ Nearly all PICA aneurysms are located intracranially, above the foramen magnum. Extracranial PICA aneurysms are rare, with few reports in literature.⁷ Microsurgical clipping remains a good treatment alternative for these aneurysms. Higher risk of rerupture has even been reported with embolization of the distal PICA aneurysm with parent artery preservation.⁸ Here we present the case of a 64-year-old male patient who presented right after a thunderclap headache, followed by a temporary loss of consciousness and disorientation. He was diagnosed with a modified Fisher 4 and Hunt and Hess 2 subarachnoid hemorrhage and found to have a partially thrombosed left PICA saccular aneurysm of the caudal loop just below the foramen magnum. The lesion was approached via a midline suboccipital craniotomy with C1 laminectomy. Microsurgical clipping of the aneurysm was performed without any complications (Video 1). Postoperatively, the patient was discharged without neurologic deficits. We present the first surgical video of the necessary steps in order to perform a microsurgical clipping of an extracranially located caudal loop PICA aneurysm through a midline suboccipital craniotomy with C1 laminectomy.

Three-Dimensional Quantitative Analysis of the Brainstem Safe Entry Zones Based on Internal Structures

OBJECTIVE

Brainstem safe entry zones (EZs) are gates to access the intrinsic pathology of the brainstem. We performed a quantitative analysis of the intrinsic surgical corridor limits of the most commonly used EZs and illustrated these through an inside perspective using 2-dimensional photographs, 3-dimensional photographs, and interactive 3-dimensional model reconstructions.

METHODS

A total of 26 human brainstems (52 sides) with the cerebellum attached were prepared using the Klingler method and dissected. The safe working areas and distances for each EZ were defined according to the eloquent fiber tracts and nuclei.

RESULTS

The largest safe distance corresponded to the depth for the lateral mesencephalic sulcus (4.8 mm), supratrigeminal (10 mm), epitrigeminal (13.2 mm), peritrigeminal (13.3 mm), lateral transpeduncular (22.3 mm), and infracollicular (4.6 mm); the rostrocaudal axis for the perioculomotor (11.7 mm), suprafacial (12.6 mm), and transolivary (12.8 mm); and the mediolateral axis for the supracollicular (9.1 mm) and infracollicular (7 mm) EZs. The safe working areas were 46.7 mm² for the perioculomotor, 21.3 mm² for the supracollicular, 14.8 mm² for the infracollicular, 33.1 mm² for the supratrigeminal, 34.3 mm² for the suprafacial, 21.9 mm² for the infrafacial, and 51.7 mm² for the transolivary EZs.

CONCLUSIONS

The largest safe distance in most EZs corresponded to the depth, followed by the rostrocaudal axis and, finally, the mediolateral axis. The transolivary had the largest safe working area of all EZs. The supracollicular EZ had the largest safe area to access the midbrain tectum and the suprafacial EZ for the floor of the fourth ventricle.

Third ventricle colloid cysts: An endoscopic case series emphasizing technical variations

Background

Colloid cyst treatment with purely endoscopic surgery is considered to be safe and effective. Complete capsule removal for gross total resection is usually recommended to prevent recurrence but may not always be safely feasible. Our objective was to assess the results of endoscopic surgery using mainly aspiration and coagulation without complete capsule resection and discuss the rationale for the procedure.

Methods

A retrospective review was conducted of 45 consecutive symptomatic patients with third ventricle colloid cysts that were surgically treated with purely endoscopic surgery from 1997 to 2018.

Results

Mean age was 35.4 years. Male-to-female ratio was 1:1. Clinical presentation included predominantly headache (80%). Transforaminal was the most used route (71.1%) followed by transeptal (24.5%) and interforniceal (4.4%). Capsule was intentionally not removed in 42 patients (93.3%) and cyst remnants were absent on postoperative MRI in 36 (85%). Mild complications occurred in 8 patients (17.8%). Surgery was statistically associated with cyst volume and ventricular size reduction. There were no serious complications, shunts or deaths. Follow-up did not show any recurrence or remnant growth that needed further treatment.

Conclusion

Gross total resection may not be the main objective for every situation. Subtotal resection without capsule removal seems to be safer while preserving good results, especially in a limited resource environment. Remnants left behind should be followed but tend to remain clinically asymptomatic for the most part. Surgical planning allows the surgeon to choose among the different resection routes and techniques available. Decisions are predominantly based on preoperative imaging and intraoperative findings.

Microsurgical Clip Placement for a Giant Anterior Communicating Artery Aneurysm With Intraluminal Thrombus: 2-Dimensional Operative Video

Giant brain aneurysms account for approximately 5% of all intracranial aneurysms. Although treatment modalities can vary widely, none is ideal for every patient. Endovascular treatment is usually preferred, especially when the large size of the aneurysm limits visualization of the brain parenchyma and parent vessels that arise from the aneurysm, making surgical clip placement across the neck a difficult task. However, despite the higher chances of morbidity, microsurgery is an effective treatment modality due to lower recurrence rates. Surgically, a wide neck, calcifications, or atheroma are complicating factors to be considered while planning the best treatment. Thus, with an appropriate case selection, a favorable outcome is feasible in most cases. Here, we present the case of a 27-yr-old female who presented with a severe headache for 7 mo and 3 mo of progressive left temporal vision loss, which was confirmed by visual field perimetry using the Humphrey visual field analyzer. Magnetic resonance angiography and digital subtraction cerebral angiography showed an anterior communicating artery complex inferiorly and medially oriented aneurysm measuring 25.4 × 16.5 mm, with a 3 mm neck. It was fed by the right A1, associated with a hypoplastic left A1, incorporating the proximal right and left A2 segments, with an intraluminal thrombus and causing mass effect on the optic chiasm and hypothalamus. This video demonstrates the microsurgical steps required to perform this operation, through a right orbitozygomatic craniotomy. At a 3-mo follow-up, the patient was neurological intact without complaints.  The patient signed the Institutional Consent Form, which allows the use of his/her images and videos for any type of medical publications in conferences and/or scientific articles.

Endoscopic Treatment of a Third Ventricular Epidermoid Cyst

Epidermoid cyst is a benign and congenital lesion of ectodermal origin. Traditionally, microsurgical techniques are used to treat these lesions, and their occurrence in the third ventricle is rare. Here, the authors report a case of epidermoid cyst in the third ventricle that presented with signs and symptoms of intracranial hypertension, which was treated safely and effectively using neuroendoscopic surgery.