Arterial supply of the upper cranial nerves: A comprehensive review

Visualizing the human olfactory projection and ancillary structures in a 3D reconstruction

Visualizing in 3D the histological microanatomy of the human olfactory projection from the olfactory mucosa in the nasal cavity to the olfactory bulbs in the cranial cavity necessitates a workflow for handling a great many sections. Here, we assembled a 3D reconstruction of a 7.45 cm3 en-bloc specimen extracted from an embalmed human cadaver. A series of 10 µm coronal sections was stained with quadruple fluorescence histology and scanned in four channels. A trained anatomist manually segmented six structures of interest in a subset of the sections to generate the ground truth. Six convolutional neural networks were then trained for automatic segmentation of these structures in 1234 sections. A high-performance computing solution was engineered to register the sections based on the fluorescence signal and segmented structures. The resulting 3D visualization offers several novel didactic opportunities of interactive exploration and virtual manipulation. By extrapolating manual counts of OSNs in a subset of sections to the calculated volume of the envelope of the entire olfactory epithelium, we computed a total of ~2.7 million OSNs in the specimen. Such empirically derived information helps assess the extent to which the organizational principles of the human olfactory projection may differ from those in mice.

Angiographic Evaluation of the Feeding Artery in Skull Base Meningioma

To identify the characteristics of feeding arteries in skull base meningioma including location and prevalence, we evaluated the distributions and types of feeding arteries in skull base meningioma by cerebral angiography and assessed relationships to tumor attachment. We enrolled patients with skull base meningioma who underwent MRI and cerebral digital subtraction angiography (DSA), from September 2015 to October 2022. Subjects comprised 115 patients (32 males, 83 females; mean age, 52.7) with 117 meningiomas, showing tumor attachments around the "cavernous sinus to the upper part of the clivus" (Area 1), "lower part of the clivus to foramen magnum" (Area 2), and "tentorium around the petrous bone" (Area 3). Frequent arteries, such as the dorsal meningeal artery (DMA), the ascending pharyngeal artery (APA), the tentorial artery (TA), and the petrosal branch (PB) of the middle meningeal artery (MMA) were analyzed in terms of their associations with tumor attachment to Areas 1-3. Meningiomas with the DMA as a feeding artery correlated with tumor attachment to Area 1 (p < 0.001). Meningiomas with the APA correlated with tumor attachment to Area 2 (p < 0.001). Meningiomas with the TA correlated with tumor attachment to Area 3 (p < 0.001). The PB correlated with Area 3 (p < 0.05). Our study founded that visualization of these arteries correlated well with specific areas. These arteries were also the main feeders in each type of skull base meningioma.

Prognostic identifier of cerebrovascular complications in tuberculous meningitis: Meta-analysis

INTRODUCTION

Cerebrovascular complications could occur in 15-57 % of patients with tuberculous meningitis (TBM). It is crucial to rapidly identify TBM patients who are at risk for stroke. This study aimed to find predictors of stroke in patients with TBM.

METHODS

This systematic review and meta-analysis were done using literature searches through online databases up to April 30th, 2022. Three independent authors performed literature screening, data extraction, and critical appraisal of the studies. Eight studies involving 1535 samples were included.

RESULTS

We analyzed data regarding demographic, comorbidity, clinical presentation, radiologic, and laboratory parameters. Overall, clinical presentation that showed outcome difference was found in patients with findings of vomiting (OR = 2.71, 95 % CI: 1.30-5.63), cranial nerve deficit (OR = 4.10, 95 % CI: 1.83-9.21), focal deficit (OR = 5.56, 95 % CI: 2.24-13.79), and altered consciousness (OR = 1.90, 95 % CI: 1.24-2.92). Some comorbidities showed significant differences such as diabetes mellitus (OR = 2.58, 95 % CI: 1.51-4.41), hypertension (OR = 5.73, 95 % CI: 3.36-9.77), ischemic heart disease (OR = 2.18, 95 % CI: 1.02-4.63), and smoking (OR = 2.65, 95 % CI: 1.22-5.77). Two radiological changes shown to have significantly higher proportions are hydrocephalus (OR = 2.50, 95 % CI: 1.74-3.58) and meningeal enhancements (OR = 3.99, 95 % CI: 1.73-9.20).

CONCLUSION

Our analysis indicated that clinical presentations of vomiting, cranial nerve deficit, focal deficit, altered consciousness; comorbidity of diabetes mellitus, hypertension, smoking history, ischemic heart disease; and radiological findings of meningeal enhancement and hydrocephalus showed significant association with stroke incidence in tuberculous meningitis.

Proper ophthalmic artery aneurysms

Background

The ophthalmic segment of the internal carotid artery (ICA) represents a common site for cerebral aneurysms. However, aneurysms of the ophthalmic artery (OphA) itself represent rare lesions and have been associated with trauma and flow-related lesions such as arteriovenous fistulas or malformations. Here, we explore clinical and radiological features of four patients managed for five proper ophthalmic artery aneurysms (POAAs).

Methods

Patients undergoing diagnostic cerebral angiogram (DCA) between January 2018 and November 2021 with newly or previously identified POAA were retrospectively reviewed. Clinical and radiological data were analyzed to identify common and unique features.

Results

Four patients with identification of five POAA were identified. Three patients suffered traumatic brain injury with subsequent identification of POAA on DCA. Patient 1 presented with a traumatic carotid-cavernous-sinus fistula requiring transvenous coil embolization and second stage flow diversion of the ICA. Patient 2 suffered a gunshot wound with ICA compromise, ethmoidal dural arteriovenous fistula (dAVF) development with rapid growth of two POAAs eventually requiring Onyx embolization. Patient 3 was assaulted and DCA showed a POAA without any other cerebrovascular pathology. Patient 4 had undergone N-butyl cyanoacrylate embolization of an ethmoidal dAVF 13 years ago with the feeding OphA carrying a large POAA. Re-DCADCA was performed for a newly developed and unrelated transverse-sigmoid-sinus dAVF.

Conclusion

Management of POAAs poses a challenge to neurovascular surgeons since POAAs inherit a risk for visual deterioration or hemorrhage. DCA facilitates identification of coexisting cerebrovascular pathology. If clinically silent and not accompanied by cerebrovascular disease, observation appears reasonable.

A case of cribriform plate dural arteriovenous fistulas with a rare complication after endovascular therapy

Background:

Cribriform plate dural arteriovenous fistulas (dAVFs) are rarely encountered. Here, we report a case of cribriform plate dAVF with a rare complication after endovascular therapy.

Case Description:

A 60-year-old man presented with severe sudden headache. Head computed tomography showed right subdural hematoma, and magnetic resonance angiography showed dilated bilateral frontal cortical vein. Digital subtraction angiography revealed cribriform plate dAVF fed by the anterior and posterior ethmoidal branches of the bilateral ophthalmic arteries. Transarterial embolization with liquid embolic material was performed and the fistula disappeared. Although magnetic resonance imaging showed the disappearance of the cribriform plate dAVF and subdural hematoma, the patient complained of anosmia after the procedure.

Conclusion:

Endovascular embolization is an effective treatment option for treating cribriform plate dAVFs. However, anosmia is a possible complication, and endovascular surgeons should take care of this complication, especially in cribriform plate dAVFs supplied with blood bilaterally.

Anatomy of the Dorsal Meningeal Artery Including Its Variations: Application to Skull Base Surgery and Diagnostic and Interventional Imaging

BACKGROUND

The blood supply to the skull base is important to surgeons and those performing interventional and diagnostic procedures in this region. However, 1 vessel with a vast distribution in this area, the dorsal meningeal artery (DMA), has had few anatomic studies performed to investigate not only its normal anatomy but also its variations. Therefore the current study aimed to analyze the DMA via cadaveric dissection.

METHODS

In 10 adults, latex-injected, cadaveric heads (20 sides), the DMA was dissected using a surgical microscope. This artery and its branches were documented and measured.

RESULTS

A DMA was identified on all sides. In the majority (85%), it was a branch of the meningohypophysial trunk or common stem with either the inferior hypophysial or tentorial arteries and always had branches that traversed the basilar venous plexus. Multiple branches of the DMA were identified and categorized as bony, dural, neural, and vascular.

CONCLUSIONS

Surgeons operating at the skull base or clinicians interpreting imaging of this area should have a good working knowledge of the DMA and its typical and variant anatomy.

Disorders of the Fourth Cranial Nerve

ABSTRACT

This review of disorders of the fourth cranial nerve includes discussion on anatomy, examination techniques, congenital and acquired etiologies, differential diagnosis, and management options. The findings of the superior oblique muscle on orbital MRI in patients with fourth nerve palsy have had a major impact on our understanding of this cranial neuropathy. In addition, briefly reviewed are rare disorders of the fourth nerve: superior oblique myokymia, Brown syndrome, and ocular neuromyotonia. It behooves the clinician to have a clear understanding of the role that the fourth cranial nerve plays in a variety of neuro-ophthalmic conditions.

What's that smell? A pictorial review of the olfactory pathways and imaging assessment of the myriad pathologies that can affect them

The olfactory pathway is composed of peripheral sinonasal and central sensorineural components. The wide variety of different pathologies that can affect the olfactory pathway reflect this complex anatomical relationship. Localising olfactory pathology can present a challenge to the reporting radiologist. This imaging review will illustrate the normal anatomy of the olfactory system and describe a systematic approach to considering olfactory dysfunction. Key concepts in image interpretation will be demonstrated using examples of olfactory pathway pathologies.

Superior cervical sympathetic ganglion block under ultrasound guidance promotes recovery of abducens nerve palsy caused by microvascular ischemia

The abducens nerve palsy is most likely caused by microvascular issue. Spontaneous recovery of vasculopathic abducens nerve palsies was common at 3-6 months. But recovery time was longer when many risk factors were present. Several patients had residual esotropia or abduction deficit. Cervical sympathetic block has an established use in treating patients with disorders related to cranial circulatory insufficiency. It causes a significant increase in cerebral blood flow. We report a case of a 67-year-old man with acute horizontal diplopia and right periocular pain. He had been diagnosed with right abducens nerve palsy caused by microvascular ischemia. We performed ultrasound-guided superior cervical sympathetic ganglion blocks. After 4 weeks, the symptoms had been completely resolved. We introduce ultrasound-guided superior cervical sympathetic ganglion blocks for management of abducens nerve palsy caused by microvascular ischemia, which could be an effective novel method to promote recovery from diplopia.

Olfactory dysfunction in patients undergoing supraorbital keyhole craniotomy for clipping of unruptured aneurysms

Olfactory performance has rarely been assessed in the perioperative phase of elective aneurysm surgery. Here, we assessed the risk for olfactory deterioration following surgical treatment of unruptured cerebral aneurysm via the supraorbital keyhole craniotomy. A retrospective review of patients with electively treated cerebral aneurysms who underwent perioperative assessment of olfactory function using a sniffin' sticks odor identification test between January 2015 and January 2016 was performed. A subgroup of patients without history of subarachnoid hemorrhage, without prior aneurysm treatment, and confirmed olfactory function underwent supraorbital keyhole craniotomy for aneurysm clipping. Microscopic and endoscopic videos were reviewed for this subgroup. Sixty-four patients who underwent elective aneurysm treatment either via surgical clipping or endovascular aneurysm obliteration were identified. Prior to treatment, 4/64 (6.3%) demonstrated bilateral anosmia. Collectively, 14 patients (21.9%) met subgroup criteria of supraorbital keyhole craniotomy for aneurysm clipping. Here, olfactory performance significantly decreased postoperatively on the side of craniotomy (ipsilateral, P = 0.007), whereas contralateral and bilateral olfactory function remained unaltered (P = 0.301 and P = 0.582, respectively). Consequently, 4/14 patients (28.6%) demonstrated ipsilateral anosmia 3 months after surgery. One patient (1/14, 7.1%) also experienced contralateral anosmia resulting in bilateral anosmia. Intraoperative visualization of the olfactory tract and surgical maneuvers do not facilitate prediction of olfactory outcome. The supraorbital keyhole craniotomy harbors a specific risk for unilateral olfactory deterioration. Lack of perioperative olfactory assessment likely results in underestimation of the risk for olfactory decline. Despite uneventful surgery, prediction of postoperative olfactory function and dysfunction remain challenging. Clin. Anat. 33:316-323, 2020. © 2019 Wiley Periodicals, Inc.

Microsurgical Anatomy of the Central Retinal Artery

BACKGROUND

The central retinal artery (CRA) has been described as one of the first branches of the ophthalmic artery.It arises medial to the ciliary ganglion and after a sinuous path within the orbital cavity it penetrates the lower surface of the dura mater that covers the optic nerve, approximately 1 cm behind the eyeball. However, the numerous anatomic descriptions that were made of the CRA have been insufficient or unclear in relation to certain characteristics that are analyzed in the present study.

METHODS

An electronic literature search was made in the PubMed database and a cadaver dissection was performed on 11 orbits fixed in formaldehyde.

RESULTS

Results were obtained regarding the source, collateral branches, curves, direction, length of the optic nerve, dural perforation site, distance, path and relations, diameter, and area of the central artery of the retina.

CONCLUSIONS

Our anatomic study innovates in 2 aspects of the CRA: area and curves. Not only was there a simple count of the number of curves, but it also analyzed the angle presented by each of the curves based on photos obtained in high definition, with a digital program to reduce the margin of error. These curvatures of the CRA were classified according to their spatial disposition within the orbital cavity based on a pattern that was easy to understand. Data were obtained from the area of the CRA on the penetration of the CRA into the dural sheath of the optic nerve.

Perioperative olfactory dysfunction in patients with meningiomas of the anteromedial skull base

Olfactory dysfunction represents a main symptom in olfactory groove meningiomas (OGM). Besides this, olfactory function has been sparsely investigated in patients suffering from supratentorial meningiomas. Here, the authors explore pre- and postoperative variables associated with olfactory dysfunction in supratentorial meningioma patients. This is a retrospective study on supratentorial meningioma patients who underwent meningioma resection between January 2015 and January 2016. Preoperative and postoperative olfactory performance was quantified using a lateralized sniffin' stick odor identification test. Meningiomas affecting the olfactory system (n = 23) were compared to meningiomas in other locations among the control group (n = 40). Meningiomas that affected the olfactory system had odds of 3.6 and 3.7 in being associated with ipsilateral (lesional) and bilateral anosmia, respectively. Subgroup analysis revealed that meningiomas causing a midline shift across the frontal base and older age represented risk factors for preoperative anosmia. The odds of experiencing acquired postoperative ipsilateral anosmia were significantly increased in olfactory system affecting meningiomas (OR 11.1). Subgroup analysis highlighted OGMs to represent the predominant location associated with deterioration. General surgical complications predisposed patients to loss of contralateral (OR 12.3) and bilateral olfactory function (OR 27.8). Older age and meningiomas causing a midline shift across the frontal base predispose patients to preoperative olfactory dysfunction. Resection of OGMs and surgical complications are risk factors for postoperative olfactory deterioration to anosmia. Likely, olfactory dysfunction is underrecognized even in OGMs. In OGM surgery, however, preoperative lateralized testing might be critical to selecting an appropriate surgical route to preserve olfactory function. Clin. Anat. 32:524-533, 2019. © 2019 Wiley Periodicals, Inc.

Flow Diverters for Treatment of 160 Ophthalmic Segment Aneurysms: Evaluation of Safety and Efficacy in a Multicenter Cohort

BACKGROUND

Treatment of ophthalmic segment aneurysms (OSA) remains challenging. Flow diverter stents (FDS) have evolved as a promising endovascular treatment option for aneurysms of the internal carotid artery and are associated with high occlusion rates and a favorable morbidity and mortality profile.

OBJECTIVE

To determine safety and efficacy of FDS for OSA in a large, multicenter cohort.

METHODS

A retrospective analysis of prospectively maintained databases of 127 consecutive patients harboring 160 OSA treated with FDS was performed. Aneurysms were classified based on location and morphology. Follow-up with digital subtraction angiography (DSA) was performed 6 to 18 months after treatment.

RESULTS

Follow-up DSA was available for 101 (63.1%) aneurysms with a mean follow-up of 18 months. Complete occlusion was observed in 90 aneurysms (89.1%), near-complete occlusion (>95%) in 3 (3%), and incomplete occlusion (<95%) in 8 aneurysms (7.9%). One aneurysm was retreated with another FDS (0.9%). No risk factors for incomplete occlusion were identified. The OA was occluded at the latest follow-up in 6 cases (7.1%). Permanent morbidity occurred in 4 patients (3.1%), and there was no mortality related to the FDS procedure.

CONCLUSION

Treatment of OSA with FDS was found to be safe and effective. The retreatment rate was extremely low and aneurysms that occluded did not reanalyze.

Can blockage or sacrifice of the middle meningeal artery lead to hydrocephalus?

BACKGROUND

The middle meningeal artery (MMA) is often sacrificed during neurosurgical procedures in the region of the pterion. This maneuver, herein, is hypothesized to be a potential reason for the development of postoperative hydrocephalus by injuring the vascular supply to the arachnoid granulations near the vertex of the skull, and thus disrupting their ability to allow for transfer of CSF from the subarachnoid space to the venous system.

MATERIALS AND METHODS

To test this theory, the middle meningeal artery was isolated at the skull base and injected with India ink. Next, the superior sagittal sinus was opened and the arachnoid granulations inspected.

RESULTS

All specimens demonstrated ink within the arachnoid granulations indicating that their blood supply is completely or at least partially via the middle meningeal artery. This finding with an illustrative case of surgical cautery of the middle meningeal artery at the skull base with subsequent development of hydrocephalus supports our hypothesis of potential role of iatrogenic MMA injury causing hydrocephalus.

CONCLUSIONS

Our cadaveric study shows that the blood supply of the arachnoid granulations of the superior sagittal sinus is via the middle meningeal artery. Additional cases of postoperative hydrocephalus following middle meningeal artery sacrifice are needed to support our hypothesis.

Middle meningeal artery: Gateway for effective transarterial Onyx embolization of dural arteriovenous fistulas

Curative transarterial embolization of noncavernous sinus dural arteriovenous fistulas (dAVFs) is challenging. We sought to evaluate the role of the middle meningeal artery (MMA) in endovascular treatment of these lesions. We performed a retrospective cohort study on patients who underwent transarterial Onyx embolization of a noncavernous sinus dAVFs with contribution from the MMA at a major academic institution in the United States from January 2009 to January 2015. Twenty consecutive patients who underwent transarterial Onyx embolization of a noncavernous sinus dAVF were identified. One patient was excluded as there was no MMA contribution to the dAVF. All of the remaining 19 patients (61.3 ± 13.8 years of age) underwent transarterial embolization through the MMA. Six patients (31.6%) presented with intraparenchymal or subarachnoid hemorrhage from the dAVF. The overall angiographic cure rate was 73.7% upon last follow up. In 71.4% of successfully treated patients transarterial embolization of the MMA alone was sufficient to achieve angiographic cure. When robust MMA supply was present, MMA embolization resulted in angiographic cure even after embolization of other arterial feeders had failed in 92.9% of patients. A robust contribution of the MMA to the fistula was the single most important predictor for successful embolization (P = 0.00129). We attribute our findings to the fairly straight, non-tortuous course of the MMA that facilitates microcatheter access, navigation, and Onyx penetration. Noncavernous sinus dAVF can be successfully embolized with transarterial Onyx through the MMA, as long as supply is robust. A transvenous approach is rarely necessary. Clin. Anat. 29:718-728, 2016. © 2016 Wiley Periodicals, Inc.