Assessing chiasm perfusion and postoperative visual function with superior hypophyseal artery indocyanine green angiograms during endoscopic endonasal surgery.

BACKGROUND: To date, there are no validated intraoperative tools to predict postoperative visual function following endoscopic endonasal surgery (EES). Assessment of post-surgical vision during surgery can help in postoperative planning and disposition and inform surgical decisions in real-time. The objective of this study was to evaluate the capability of intraoperative endoscopic indocyanine green (ICG) angiography to measure optic chiasm perfusion and determine its relationship with postoperative visual function. METHODS: A retrospective review was performed on patients undergoing EES for sellar and suprasellar lesions. ICG was injected prior to surgical closure at a time when the optic chiasm and anterior circulation were visible. Luminescence of the superior hypophyseal artery (SHA) branches enveloping the optic chiasm was registered 10 seconds after ICG penetration into the anterior cerebral arteries (ACAs). Pre and post-operative visual acuity and field exams were used to assess visual function. Patients with and without new deficits were compared to examine statistical association with intraoperative ICG findings. RESULTS: Twenty patients were included (mean age 49 years, 55% female). Eighteen patients displayed stable or improved vision after resection and demonstrated luminescence of all chiasmatic branches within 10 s of ACA fluorescence. Two patients experienced new postoperative visual deficits. Upon review, their ICG administrations showed no fluorescence of the SHA branches enveloping the chiasm. A lack of chiasm fluorescence within ten seconds of ACA fluorescence was associated with new postoperative vision deficits (p = 0.005). CONCLUSIONS: This study shows that the lack of ICG fluorescence of SHA branches at the chiasm correlates with ischemic changes and new post-operative bitemporal hemianopsia. Lack of chiasm fluorescence after 10 seconds of observation reflects compromised chiasm perfusion and likely new post-surgical visual deficits.

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.

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.

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.

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.

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.

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.

[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.

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.

[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.

Chiasmal apoplexy: hemorrhage from a cryptic vascular malformation in the optic chiasm.

We describe three patients with acute chiasmal visual field loss caused by hemorrhage within an intrachiasmal arteriovenous malformation. One patient had five episodes; vision improved three times without treatment and twice after surgical decompression. Surgical intervention restored vision in two of the three patients. The role for surgery is indefinite, but may be indicated if the visual defect remains static for 1 week or progresses. Decompression is likely to be most effective if done early. The approach to the optic chiasm should be transcranial, not transsphenoidal. A radiologically normal sella turcica favors the diagnosis of chiasmal apoplexy in the acute chiasmal syndrome.

Total blindness after trivial frontal head trauma: bilateral indirect optic nerve injury.

A 10-year-old girl developed bilateral blindness and partial third nerve paresis immediately following a closed head injury. Bilateral optic atrophy developed subsequently. This is the first report of an association between second and third nerve injuries after minor head trauma in the absence of a preexisting lesion. The pathophysiology of indirect injury to the optic nerve under these circumstances is uncertain, but the lesions in this patient seemed to be due to ischemia.

Regional optic nerve blood flow and its autoregulation.

An autoradiographic method (14C-iodoantipyrine autoradiography) was used to measure regional optic nerve blood flow (ONBF) under basal conditions in 11 adult female cats. Flow was measured in six regions of the optic nerve: (1) prelaminar, (2) laminar, (3) 1 mm post-laminar, (4) 4 mm post-laminar, (5) 6 mm post-laminar, and (6) intracranial optic nerve and chiasm. A gradient of flow rates was found with relatively high flow in the prelaminar, laminar, and 1-mm post-laminar optic nerve, and significantly lower flow in the 4- and 6-mm post-laminar nerve and in the intracranial optic nerve and chiasm. Blood flow in the 4- and 6-mm post-laminar nerve and in the intracranial nerve and chiasm was comparable to previously reported values for cerebral white matter in the cat. With alteration of mean arterial blood pressure (MABP), optic nerve blood flow demonstrated autoregulatory compensation in all areas.

Chiasmal syndrome caused by arteriovenous malformations.

Only four cases of chaismal syndromes caused by arteriovenous malformations (AVMs) have been reported. We have examined two patients with chiasmal dysfunction caused by an AVM. In one patient, the AVM was suspected only after angiography. However, the presence of an angioma of the lip might have been a clue to the diagnosis. In the other patient, seizures and pulsating proptosis led to the correct diagnosis before angiography was performed. This patient also had episodes of transient bilateral blindness, presumably caused by postictal states or by periodic shunting with ischemia (chiasmal steal).

Chiasmal infarction and sudden blindness caused by mucormycosis in AIDS and diabetes mellitus.

PURPOSE: To report rapidly progressive rhino-orbitocerebral mucormycosis in a 47-year-old woman with both diabetes mellitus and the acquired immunodeficiency syndrome (AIDS). METHOD: Case report including postmortem examination of the eyes, orbit, and brain of a patient with rhino-orbitocerebral mucormycosis, diabetes mellitus, and AIDS. RESULTS: Invasion by hyphae of the Rhizopus species produced an occlusive vasculitis and massive infarction of the optic chiasm. Fungal organisms were discovered in multiple granulomata of the optic nerve. CONCLUSION: Infarction at the optic chiasm probably caused sudden blindness in this patient.

Ischemic chiasma syndrome.

Thirty patients with chiasma syndrome attributed to ischemic processes of various origins are described. The initial diagnosis was made after an investigation based on polytome pneumoencephalography and angiography. This diagnosis was confirmed later with the use of high-resolution computed tomography (CT) and refined angiographic techniques. The ischemic chiasma syndrome may be classified into five pathogenetic categories: (1) mechanical compression of the chiasm secondary to ectatic tortuous arteries; (2) vascular occlusion secondary to atheromatous plaque formation; (3) arachnoiditis with fibrosis; (4) arteritis of various origins; and (5) postpartum necrosis. Sophisticated neurologic procedures including magnification angiography and high-resolution CT are essential in ruling out a mass lesion and correlating the clinical and radiologic findings of this syndrome.

Ischemic chiasmal syndrome and hypopituitarism associated with progressive cerebrovascular occlusive disease.

Two interesting patients are described with unique clinical and radiographic manifestations of progressive bilateral stenosis-occlusion of the distal internal carotid arteries. Their clinical presentations, ischemic chiasmal syndrome and hypopituitarism, are extremely rare, despite extensive occlusion of the circle of Willis. In one of these patients, the configuration of collateral vessels around the optic chiasm on computed tomography (CT) was so rounded and discrete that it actually had an appearance suggesting a pituitary tumor or an aneurysm. In the second patient, a pseudoaneurysm and a very large intracerebral hematoma with a ring of contrast enhancement were the radiographic manifestations.

Liliequist's membrane is a fold of the arachnoid mater: study using sheet plastination and scanning electron microscopy.

OBJECTIVE: The subarachnoid space consists of a number of distinct subarachnoid cisterns. They are separated from each other by trabecular walls, one of which is Liliequist's membrane. The aim of this study was to investigate the anatomic characteristics of Liliequist's membrane. METHODS: The study used a combined approach, consisting of the modified E12 sheet plastination method for 3 adult cadavers and gross anatomic dissection for 35 cadavers, 2 of which were further examined using scanning electron microscopy. RESULTS: The results from this study indicate that 1) Liliequist's membrane is an avascular fold of the arachnoid mater that lacks openings and spreads out laterally, being in direct continuity with the arachnoid mater covering the tentorium; 2) the carotid-chiasmatic walls, which separate the chiasmatic cistern and carotid cisterns and had been considered to be parts of Liliequist's membrane, are vascular and incomplete trabecular walls and should not be considered parts of Liliequist's membrane; and, 3) as a fold of the arachnoid mater, Liliequist's membrane is not directly attached to the temporal lobes and oculomotor nerves. CONCLUSION: Liliequist's membrane is a double-layer fold of the arachnoid mater and has anatomic characteristics different from those of arachnoid trabecular walls.