Morphometric Comparison of the Pterional Trans-Sylvian and the Pretemporal Trans-Clinoidal Approaches to the Posterior Communicating Artery

Rosai-Dorfman sphenoorbital histiocytosis with intraparenchymal invasion: Do we have to consider this skull base pathology as a malignant disease?

Background

Rosai-Dorfman disease (RDD) is a rare type of histiocytosis that can manifest with diverse symptoms. It usually presents with systemic involvement, and only a few cases have been reported at the level of the skull base. RDD typically follows a benign course during the progression of the disease. In this particular case reported, after the skull base invasion, the disease started to infiltrate the brain parenchyma. Our objective for this case report was to present this particular progression pattern and the nuances of its surgical treatment. In addition, a revision of the current literature was performed about skull base RDD with intracranial invasion and brain parenchyma infiltration not previously described.

Case Description

We are presenting the case study of a 57-year-old male patient who was experiencing severe headaches and an increase in volume in the right fronto-orbital region. On clinical examination, no neurologic clinical symptoms were observed. Contrast computed tomography and magnetic resonance imaging showed a tumor mass that affected the right orbit, frontal paranasal sinus, greater sphenoid wing, and right frontal lobe with moderate adjacent brain edema. The patient underwent surgery using an extended pterional approach with intracranial, orbital decompression, and frontal sinus cranialization, accompanied by frontal lobe tumor resection. Neuropathologic diagnosis revealed a Rosai-Dorfman histiocytosis disease.

Conclusion

The etiopathogenesis of RDD is still not completely understood. The current literature considers this disease to have a predominantly benign course. Nevertheless, as we have shown in this case, it may, in some cases, present direct parenchymal invasion. We consider that prompt surgical treatment should be ideal to avoid the local and systemic progression of the disease.

True Posterior Communicating Artery Aneurysm Associated With a Posterior Communicating Segment Aneurysm: A Case Report

"True" posterior communicating artery (PComA) aneurysms are one of the rarest of all intracranial aneurysms. Diagnosis of this kind of aneurysm and treatment continue to be challenging for neurosurgeons because of the surrounding structures and their importance. Concomitant vascular anomalies, like dissections or hypoplasia, are frequently found with these aneurysms. Multiple aneurysms in the posterior communicating segment are even rarer than true PComA aneurysms alone. To achieve a safe clipping in patients with multiple aneurysms in this location, some coadjuvant maneuvers may be performed, like resection of the anterior part of the uncus. By presenting this case, we aim to show how we managed to treat these rare aneurysms with good outcomes for the patient and microsurgical resolution.  We present a representative case of a 50-year-old female with headache, nausea, language disturbances, left hemiparesis, and deterioration of consciousness, referred to our hospital with a diagnosis of subarachnoid hemorrhage (Hunt & Hess grade 3, Fisher grade 4) secondary to a rupture of a true PComA aneurysm. Urgent surgical clipping was performed, and during surgery, a junctional aneurysm and a true PComA aneurysm were found very close to each other, complicating the procedure, so to have more space to work and perform a safe clipping, we resected the anterior part of the uncus, which broadened the retrocarotid space, performing the clipping with complete exclusion of both aneurysms and no complications. The patient was discharged after five days with right partial III nerve palsy. Postsurgical CT angiography (CTA) and perfusion images showed the permeability of branches distal to the clips.  Knowledge of microsurgical and vascular anatomy is key to the successful treatment of this type of aneurysm, especially when we have multiple aneurysms so close to each other, like in this case, because of the relation with cranial nerves and perforators. Performing extra procedures or transurgical maneuvers like the anterior resection of uncus to broaden our working space is always helpful to avoid complications or major deficits.

Cisternal, Falciform, and Optic Canal Decompression Influencing Optic Nerve Biomechanics: A Microsurgical Anatomic Study

BACKGROUND

Questions remain regarding optic nerve (ON) physiology, mechanical compliance, and microvasculature, particularly surgical outcomes and atypical visual field defects associated with sellar/parasellar pathology (eg, tumors and aneurysms).

OBJECTIVE

To study the microsurgical/histological anatomy of each ON segment and corresponding microvasculature, calculate area of optic-carotid space at each decompression stage, and measure ON tension before/after compression.

METHODS

Five cadaveric heads (10 sides) underwent sequential dissection: (1) intradural (arachnoidal) ON dissection; (2) falciform ligament opening; (3) anterior clinoidectomy, optic canal decompression, and ON sheath release. At each step, we pulled the nerve superiorly/laterally with a force meter and measured maximal mobility/mechanical tension in each position.

RESULTS

Cisternal ON microvasculature was more superficial and less dense vs the orbital segment. ON tension was significantly lower with higher mobility when manipulated superiorly vs lateromedially. Optic-carotid space significantly increased in size at each decompression stage and with ON mobilization both superiorly and laterally, but the increase was statistically significant in favor of upward mobilization. At decompression step, upward pull provided more space with less tension vs side pull. For upward pull, each step of decompression provided added space as did side pull.

CONCLUSION

Opening the optic canal, falciform ligament, and arachnoid membrane decompresses the ON for safer manipulation and provided a wider optic-carotid surgical corridor to access sellar/parasellar pathology. When tailoring decompression, the ON should be manipulated superiorly rather than lateromedially, which may guide surgical technique, help prevent intraoperative visual deterioration, facilitate postoperative visual improvement, and help understand preoperative visual field deficits based on mechanical factors.

How I do it: proximal control in parkinson's triangle for a very large paraclinoid aneurysm

Background

Paraclinoid aneurysms, especially when they are large, can be quite difficult to treat, both endovascularly and through microsurgical clip reconstruction. There are many possibilities to approach this region surgically, and most hinge on total or partial removal of the anterior clinoid process. Gaining proximal control may be a challenge when space is limited, which is why Parkinson’s triangle may be a viable alternative in some cases.

Methods

We describe in a stepwise fashion the steps used to reconstruct a very large paraclinoid aneurysm. We first attempted to gain proximal control in the carotid cave and later in Parkinson’s triangle because of limited manoeuvrability.

Conclusion

Proximal control in Parkinson’s triangle can be a safe alternative when the post-clinoidal segment of the internal carotid artery (ICA) is short and working space is limited in paraclinoid aneurysm microsurgical clip reconstruction.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00701-021-04961-6.