A neurosurgical assessment of the blood supply in the optochiasmatic system: a cadaveric-anatomic study.

The chiasmal and subchiasmal surfaces are of critical importance in connection with the performance of surgical procedures owing to the critical blood supply to these areas. Recently, the perforating arteries providing the blood to the optic nerves and chiasm have gained attention as they significantly affect the morbidity from surgical approaches. Intraoperative preservation of these perforating arteries is considered critical to prevent further visual loss. Thirty autopsy specimens, including the optic apparatus, were examined for their perforating arteries feeding the optic chiasm and optic nerves. The optic nerves and chiasmal surfaces were divided into four zones based on the presence and numbers of perforating arteries as anterior superior-posterior superior surfaces and anterior inferior-posterior inferior surfaces. The superior surface of the optic chiasm was supplied by the A1 segments of the bilateral anterior cerebral arteries and by the perforating arteries originating from the anterior communicating artery. On the other hand, the inferior surface of the optic chiasm was fed by the bilateral posterior communicating arteries and by the supraclinoidal segments of the bilateral carotid arteries. We demonstrated the anatomical involvement of a large number of nourishing arteries in feeding the optic apparatus related to the perforating arteries by classifying them into zones based on the surgical approaches, which has been rarely reported in the literature.

The Superior Hypophyseal Arteries: Anatomical Study with an Endoscopic Endonasal Perspective.

BACKGROUND: The use of high-definition endoscopes in extended transsphenoidal approaches to the suprasellar area has significantly improved visualization of its vascularization. OBJECTIVE: To systematically examine the superior hypophyseal arteries (SHAs) anatomy from an endonasal endoscopic perspective. METHODS: The endoscopic endonasal transsphenoidal trans-tuberculum approach was performed in 19 adult, fresh and latex injected specimens. Dissections recordings were reviewed to analyze SHAs type, number, and branches, as well as internal carotid arteries (ICA) branches that vascularized optic nerves and chiasm. RESULTS: Identification of SHAs was possible in all specimens (37/38 sides). The number of SHAs varied from 1 to 3 per side (mean: 1.7). The anterior superior hypophyseal artery was visible in almost all cases (35/37 sides) and originated at the level of the carotid cave in 18/35 specimens; number of branches ranged from 1 to 6 (mean: 3.5), directed to the optic nerve (86%), chiasm (57%), infundibulum (86%), and/or parallel to the pituitary stalk (74%). The 4 main branches and patterns, originally described by McConnell in 1953, were confirmed. The posterior superior hypophyseal artery was evident in 28/37 sides with number of branches ranging from 0 to 4 (mean: 2.1), directed to the optic chiasm (50%), optic tract (32%), infundibulum (79%), and/or pituitary stalk (36%). The surgical implications of this study, together with anatomical and clinical videos, are also briefly discussed. CONCLUSION: SHAs constitute a complex of anterior and posterior branches that stem from the medial ICA with different patterns, vascularizing the optic apparatus and pituitary stalk.

Pituitary Tuberculoma.

Tuberculosis rarely involves the hypothalamo-pituitary region and constitutes only 1% of the lesions involving the sellar and/or suprasellar region. Coleman and Meredith first reported pituitary tuberculosis in 1940, and only a handful of cases have been reported ever since. It may manifest as a chiasmal syndrome due to compression of the optic chiasm or as hypopituitarism due to pituitary destruction. It has a characteristic radiological appearance and can mimic a pituitary adenoma. Diagnostic procedures, such as trans-sphenoidal biopsy, are crucial for accurate diagnosis. We report a case of a 32-year male, who presented with complaints of headache and decreased visual acuity for the past 6 months. Eye examination revealed bitemporal hemianopsia. Brain MRI scan showed a mass in the sella with features suggestive of pituitary adenoma. Transcranial resection of the mass was performed; histopathology of the excised mass proved it to be a pituitary tuberculoma.

Extrinsic and intrinsic blood supply to the optic chiasm.

Although there have been many studies of the arterial cerebral blood supply, only seven have described the optic chiasm (OC) blood supply and their results are contradictory. The aim of this study was to analyze the extrinsic and intrinsic OC blood supply on cadaveric specimens using dissections and microcomputer tomography (Micro-CT). Thirteen human specimens were dissected and the internal or common carotid arteries were injected with red latex, China Ink with gelatin or barium sulfate. Three Micro-CTs were obtained to reveal the intrinsic blood supply to the OC. The superior hypophyseal arteries (SupHypA) (13/13) and posterior communicating artery (PCoA) (12/13) supplied the pial network on the inferior side of the OC. The first segment of the anterior cerebral artery (ACA) (10/10), SupHypA (7/10), the anterior communicating artery (ACoA) (9/10), and PComA (1/10) supplied the pial network of its superior side. The intrinsic OC blood supply was divided into three networks (two lateral and one central). Capillaries entering the OC originated principally from the inferior pial network. The lateral network capillaries had the same orientation as the visual lateral pathways, but the central network was not correlated with the nasal fibers crossing into the OC. There was no anastomosis in the pial or intrinsic networks. Only SupHypA, PCoA, ACoA, and ACA were involved in the OC blood supply. Because there was no extrinsic or intrinsic anastomosis, all arteries should be preserved. Tumor compression of the inferior intrinsic arterial network could contribute to visual defects. Clin. Anat. 31:432-440, 2018. © 2017 Wiley Periodicals, Inc.

The optic chiasm.

The optic chiasm is formed when the optic nerves come together in order to allow for the crossing of fibers from the nasal retina to the optic tract on the other side. This enables vision from one side of both the eyes to be appreciated by the occipital cortex of the opposite side. This review makes note of the embryology, anatomy and vascular supply of the optic chiasm, then discusses the clinical syndromes associated with chiasmal disease, and the diseases which commonly influence its function.

Impact of chiasma opticum malformations on the organization of the human ventral visual cortex.

Congenital malformations of the optic chiasm, such as enhanced and reduced crossing of the optic nerve fibers, are evident in albinism and achiasma, respectively. In early visual cortex the resulting additional visual input from the ipsilateral visual hemifield is superimposed onto the normal retinotopic representation of the contralateral visual field, which is likely due to conservative geniculo-striate projections. Counterintuitively, this organization in early visual cortex does not have profound consequences on visual function. Here we ask, whether higher stages of visual processing provide a correction to the abnormal representation allowing for largely normal perception. To this end we assessed the organization patterns of early and ventral visual cortex in five albinotic, one achiasmic, and five control participants. In albinism and achiasma the mirror-symmetrical superposition of the ipsilateral and contalateral visual fields was evident not only in early visual cortex, but also in the higher areas of the ventral processing stream. Specifically, in the visual areas VO1/2 and PHC1/2 no differences in the extent, the degree of superposition, and the magnitude of the responses were evident in comparison to the early visual areas. Consequently, the highly atypical organization of the primary visual cortex was propagated downstream to highly specialized processing stages in an undiminished and unchanged manner. This indicates largely unaltered cortico-cortical connections in both types of misrouting, i.e., enhanced and reduced crossing of the optic nerves. It is concluded that main aspects of visual function are preserved despite sizable representation abnormalities in the ventral visual processing stream.

Functional organisation of visual pathways in a patient with no optic chiasm.

Congenital achiasma offers a rare opportunity to study reorganization and inter-hemispheric communication in the face of anomalous inputs to striate cortex. We report neuroimaging studies of a patient with seesaw nystagmus, achiasma, and full visual fields. The subject underwent structural magnetic resonance imaging (MRI), diffusion tensor imaging (DTI) studies, and functional MRI (fMRI) using monocular stimulation with checkerboards, motion, objects and faces, as well as retinotopic quadrantic mapping. Structural MRI confirmed the absence of an optic chiasm, which was corroborated by DTI tractography. Lack of a functioning decussation was confirmed by fMRI that showed activation of only ipsilateral medial occipital cortex by monocular stimulation. The corpus callosum was normal in size and anterior and posterior commissures were identifiable. In terms of the hierarchy of visual areas, V5 was the lowest level region to be activated binocularly, as were regions in the fusiform gyri responding to faces and objects. The retinotopic organization of striate cortex was studied with quadrantic stimulation. This showed that, in support of recent findings, rather than projecting to an ectopic location contiguous with the normal retinotopic map of the ipsilateral temporal hemi-retina, the nasal hemi-retina's representation overlapped that of the temporal hemi-retina. These findings show that congenital achiasma can be an isolated midline crossing defect, that information transfer does not occur in early occipital cortex but at intermediate and higher levels of the visual hierarchy, and that the functional reorganisation of striate cortex in this condition is consistent with normal axon guidance by a chemoaffinity gradient.

The optic chiasm.

In the first part of this chapter the anatomy and vascular supply of the chiasm are recounted, and the visual symptoms that may arise in chiasmal disease are noted. The neuro-ophthalmic signs, including the pattern of visual field defects, appearance of the optic disc, and various uncommon clinical accompaniments, are described. The second part deals with a comprehensive list of disease processes that may directly or indirectly affect the chiasm. These are divided into inflammatory disorders, including sarcoidosis, multiple sclerosis, and idiopathic chiasmitis; infective disorders, including tuberculosis; and a large section on tumors, including pituitary adenomas, cysts, and choristomas, malignant disorders, including germ cell tumors and glioma, and meningioma; and finally vascular disorders and compression due to hydrocephalus. In each case the clinical features and management of the disorder are noted, as well as the prognosis for visual improvement following treatment.

Indocyanine green videoangiography of optic cavernous angioma - case report - .

The intraoperative findings of an indocyanine green videoangiography (ICG-VAG) study of a cavernous angioma located in the optic chiasm are reported. A 23-year-old Japanese man suddenly developed visual field loss, and magnetic resonance imaging suggested the presence of a suprasellar tumor in contact with the optic chiasm. Preoperative angiography did not clearly show any tumor shadow. Right fronto-temporal craniotomy was performed, and an aggregation of blood vessels was seen on the right surface of the optic chiasm. Cavernous angioma was suspected. ICG-VAG was begun 22 seconds after the beginning of contrast agent infusion via a peripheral blood vessel. The lesion remained unstained, although the brain surface, an artery superior to the optic nerve, and veins were visualized. The cavernous angioma was resected following surface coagulation. ICG-VAG is currently being evaluated for future application in the differential diagnosis based on imaging findings, and the present case provides an important example of intraoperative ICG-VAG imaging of an unoperated cavernous angioma.

Microsurgical management of tuberculum sellae meningiomas by the frontolateral approach: surgical technique and visual outcome.

OBJECTIVES: The aim of this study was to evaluate visual outcome in patients with tuberculum sellae meningioma (TSM) treated microsurgically using the frontolateral or fronto-orbital approach and optic canal unroofing to resect tumor involvement of the optic canal. METHODS: Data from 67 patients with TSMs who underwent microsurgical treatment by a frontolateral approach (n=44) or fronto-orbital approach (n=23) between January 2002 and December 2008 were retrospectively collected and analyzed. Change in visual function was evaluated as the main outcome. RESULTS: Total tumor resection was achieved in 62 of 67 cases (92.4%). Postoperative, visual acuity was improved in 87 eyes (64.9%) and unchanged in 39 eyes (29.1%), and the optic nerve was therefore preserved in 126 of 134 eyes (94.0%). Visual field deficits were improved or stable in 65 eyes, no patient experienced worsening of vision in both eyes. There was no mortality in our series. CONCLUSIONS: The frontolateral approach with microsurgical dissection of the Sylvian fissure provides quick access to TSMs, which can be resected safely and totally. Visual function is improved and neurological and ophthalmological morbidity is minimal. Optic nerve decompression by intradural clinoidectomy and optic canal unroofing is likely to increase the rate of reducing or eliminating preoperative visual symptoms.

Functional impairments caused by chiasma syndromes prior to and following transsphenoidal pituitary adenoma surgery.

PURPOSE: To describe the functional impairment caused by chiasma syndromes (CS) prior to and following transsphenoidal pituitary adenoma surgery. METHODS: Pertinent data of a successive series of patients operated transsphenoidally for the first time for pituitary adenoma were retrospectively analyzed. The degree of functional impairment caused by the impairment of vision was quantified according to the resulting degree of disability (DOD). A DOD of > or =30 is considered substantial. RESULTS: None of the 197 of 304 (64.9%) patients without preoperative chiasma syndrome (CS) experienced postoperative worsening of their visual acuity or their visual fields. Thus, no change of their vision-related DOD (V-DOD) did occur. One hundred and seven (35.1%) of the patients presented preoperatively with CS. Postoperatively, 42.9% of the CS remitted completely, 38.3% improved, 11.2% remained unchanged, and 7.4% worsened. Accordingly, the median V-DOD improved significantly from 30 (0; 100) to 0 (0; 100). The prevalence of patients with V-DOD > or =30 dropped significantly from 51.4% preoperatively to 16.4% postoperatively. Postoperatively, the median V-DOD improved significantly up to 3 months postoperatively. Thereafter, no further significant changes occurred. However, in patients with preoperative CS, the median V-DOD as well as the prevalence of patients with a V-DOD > or =30 remained postoperatively significantly higher compared to patients without preoperative CS. CONCLUSIONS: Visual impairments due to CS frequently caused substantial DOD preoperatively. Postoperatively, the median degree of V-DOD as well as the prevalence of substantial V-DOD improved significantly. However, in patients with preoperative CS, V-DOD remained postoperatively significantly higher than V-DOD of patients without preoperative CS.

59-year old female with suprasellar mass.

Intracranial capillary hemangiomas are extremely rare. Only 14 histologically proven cases have been reported in the literature. A 59-year-old-female presented with a severe headache for 3 weeks. Brain MRI revealed a homogeneous contrast enhancing round mass lesion in the pituitary stalk and infundibular recess. We performed endoscopic biopsy. In the operative field, a reddish, well-circumscribed mass from the infundibular recess protruded into the third ventricle and it was separated from the optic chiasm. The tumor appeared a highly vascular. Histopathological examination demonstrated an aggregation of thin-walled capillaries, consistent with capillary hemangioma.

[Intrachiasmal hematoma].

This case report describes 41-year-old female who suffered from progressive visual loss due to chiasmal apoplexy. Her neurological examination revealed bitemporal hemianopia without any pathological changes of optic disks. MRI showed round-shape, hyperintensive on T1WI and T2WI lesion inside the chiasm without enhancement after IV contrast administration. The lesion was suspicious of acute or subacute hemorrhage. MRI and CT scans revealed characteristic signs that supported the diagnosis of intrachiasmal hemorrhage. Surgery was performed via a pterional approach. Minimally invasive surgical intervention to chiasm allowed us to minimize the risk of further visual deterioration in postoperative period. Meta-analysis of publications highlights the various aspects of diagnosis and management of intrachiasmal hemorrhages.

Chiasmal and/or optic nerve apoplexy due to rupture of vascular malformation--case report--.

An 8-year-old boy presented with a rare case of optic nerve apoplexy caused by an arteriovenous malformation (AVM) manifesting as severe headache and blurred vision. Computed tomography (CT) showed a hyperdense suprasellar mass. Magnetic resonance (MR) imaging indicated a hematoma in the right optic nerve. MR angiography showed normal vessels. Right fronto-temporal craniotomy identified an aggregate of abnormal, nidus-like vessels adhering to the medial surface of the swollen right optic nerve and a drainer-like ectatic red vein. The diagnosis was probable AVM. To avoid optic nerve damage, the malformation was left intact. Two years later, the boy was readmitted with headache. CT showed bleeding, and angiography revealed feeder arteries and nidus in the suprasellar lesion. The diagnosis was optic nerve apoplexy due to AVM. His symptoms improved without intervention within days. He has not experienced any recurrence of the bleeding for 2 years.

Accurate course and relationships of the intraorbital part of the ophthalmic artery in the sagittal plane.

INTRODUCTION: Knowledge of variations in the course and distribution of the intraorbital part of ophthalmic artery (OA) is necessary for the diagnosis and treatment of anterior cranial and orbital disorders. MATERIAL: 38 human cadaver dissections to demonstrate the microsurgical anatomy of the intraorbital part of the OA were studied in three stages, considering its neighbourhood with the optic nerve in the sagittal plane. RESULTS: The first part of the OA was located on the inferolateral aspect of the optic nerve in 89.47%. The diameter and the length of the first part of the OA were 1.69+/-0.34 mm and 7.58+/-0.89 mm. 73.68% of the cases crossed the optic nerve superiorly, and 26.31% inferiorly. The diameter and length of the second part of the OA were as 1.52+/-0.29 mm and 4.12+/-0.85 mm. The diameter and length of the third part of the OA were 1.07+/-0.18 mm and 4.12+/-0.85 mm. The first branch of the intraorbital part of the OA was the central retinal artery in 26.31% of the specimens. CONCLUSION: A better understanding of the vascular anatomy of the orbit should allow for the modification of surgical techniques to reduce bleeding during biopsy or excision of orbital structures.

[Cavernous angioma of the second cranial nerve and chiasmatic apoplexy]. / Angioma cavernoso del segundo nervio craneal y apoplejía quiasmática.

We present the case of a female patient who developed chiasmatic apoplexy and menstrual alterations. CT scanning showed a suprasellar hemorrhage. She underwent surgery with the presumptive diagnosis of pituitary tumor. At surgery, we find a brown-grayish lesion involving left optic nerve and chiasm. Cavernous angioma was diagnosed by histopathology. Cavernous angiomas constitute nearly 15% of all central nervous system vascular malformations. Location at the optic pathway is very rare, but must to be ruled out in the diagnosis of a patient with chiasmatic and/or optic apoplexy. Surgery is useful in preventing worsening of the previous deficit or a new visual defect.

Giant intracranial aneurysm of the anterior communicating artery treated by direct surgery using A3-A3 side-to-side anastomosis and A3-RA graft-STA anastomosis.

We describe a giant aneurysm of the anterior communicating artery (ACoA) which was treated with a STA-RA graft-A3 bonnet bypass and A3-A3 side-to-side anastomosis. A giant and partially thrombosed ACoA aneurysm was partially coated 3 years before his current presentation, its gradual increase producing visual field disturbances. An A3-A3 side-to-side anastomosis and STA-RA graft-A3 bonnet bypass were performed. The aneurysm was dissected, and the thrombus removed under transient parent-artery occlusion. The aneurysmal neck was successfully clipped without encountering ischemic changes. This strategy may be useful for treating giant or thrombosed aneurysms in the region of the ACoA.