Extrinsic and intrinsic blood supply to the optic chiasm

Visual Evoked Potential Can Predict Deterioration of Visual Function After Direct Clipping of Paraclinoid Aneurysm With Anterior Clinoidectomy

BACKGROUND

The role of visual evoked potential (VEP) in direct clipping of the paraclinoid internal carotid artery (ICA) aneurysm remains uncertain.

OBJECTIVE

To examine whether intraoperative neuromonitoring with VEP can predict deterioration of visual function after direct clipping of the paraclinoid ICA aneurysm with anterior clinoidectomy.

METHODS

Among consecutive 274 patients with unruptured cerebral aneurysm, we enrolled 25 patients with paraclinoid ICA aneurysm treated by direct clipping after anterior clinoidectomy with intraoperative neuromonitoring with VEP in this study. We evaluated the visual acuity loss (VAL) and visual field loss (VFL) before surgery, 1 month after surgery, and at the final follow-up.

RESULTS

The VAL at 1 month after surgery (VAL1M) and VAL at the final follow-up (Final VAL) were significantly related to the reduction rate of VEP amplitude at the end of surgery (RedEnd%), more than 76.5%, and the maximal reduction rate of VEP amplitude during surgery (MaxRed%), more than 66.7% to 70%. The VFL at 1 month after surgery (VFL1M) and the VFL at the final follow-up (Final VFL) were significantly related to MaxRed% more than 60.7%.

CONCLUSION

VAL1M, Final VAL, VFL1M, and Final VFL could be significantly predicted by the value of RedEnd% and MaxRed% in direct clipping of Al-Rodhan group Ia, Ib, and II paraclinoid ICA aneurysms with anterior clinoidectomy.

Improvement of optic nerve pial blood supply visualized through indocyanine green videoangiography after resection of a tuberculum sellae meningioma: 2-dimensional operative video

Ischemia of the optic nerve (ON) is an important cause of visual field deficit provoked by tuberculum sellae (TS) meningiomas. Indocyanine green (ICG) videoangiography could provide prognostic information. Moreover, it allows new insight into the pathophysiology of visual disturbance. The authors present the case of a 48-year-old woman with visual field impairment. Magnetic resonance imaging (MRI) depicted a lesion highly suggestive of a TS meningioma. Following microsurgical resection, ICG videoangiography demonstrated improvement of right ON pial blood supply. In this case, there was one lesion causing visual impairment through both direct compression over the left ON and ischemia to the right nerve.

The video can be found here: https://stream.cadmore.media/r10.3171/2021.10.FOCVID21155

Bitemporal hemianopsia secondary to ischemic chiasmopathy following mechanical thrombectomy

Purpose

To report a case of bitemporal hemianopsia due to ischemic chiasmopathy after mechanical thrombectomy of a right distal internal carotid artery (ICA) occlusion.

Observations

A 60-year-old female presented with left sided weakness and difficulty speaking and was found to have suffered a right internal carotid artery occlusion 10 days after tricuspid valve replacement for severe symptomatic tricuspid valve disease. She underwent mechanical thrombectomy and in hospital and at further follow ups was noted to have a bitemporal hemianopsia, consistent with an ischemic optic chiasmopathy.

Conclusions and importance

The optic chiasm is vascularized by multiple arteries of the Circle of Willis. As such, ischemic optic chiasmopathy is rare. Clinicians should consider ischemic chiasmopathy following cardiac and other surgical procedures including mechanical thrombectomy of the ICA or its branches.

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Bitemporal hemianopsia usually occurs from compression of the optic chiasm.

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The optic chiasm is supplied by multiple arteries - ischemic chiasmopathy is uncommon.

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This case describes ischemic chiasmopathy post mechanical thrombectomy.

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.

Ischemic chiasmal syndrome associated with posterior communicating artery (PCoA) and tuberothalamic artery (TA) infarction: a case report

Lesions affecting the body of the optic chiasm typically produce bitemporal hemianopia. The blood supply comes from the anterior communicating artery, anterior cerebral, posterior communicating, posterior cerebral, and basilar arteries. We herein report a young patient admitted to the emergency department with acute confusion, left-sided hemiparesis, hemihypoesthesia, and dysarthria. Bitemporal hemianopia was detected after resolution of confusion. On cranial magnetic resonance imaging (MRI), infarction in the right anterolateral thalamus in the territory of tuberothalamic artery (TA) and in posterior chiasma in the territory of the posterior communicating artery (PCoA) was revealed. Cerebral MR angiography showed luminal irregularity of the PCoA. The patient was presented to draw attention to the rare entity ischemic chiasmal syndrome.

Retinal nerve fibre and ganglion cell inner plexiform layer analysis by optical coherence tomography in asymptomatic empty sella patients

Purpose: To investigate the clinical importance of the thicknesses of the retinal nerve fibre (RNFL) and ganglion cell and inner plexiform layer (GCL+) by spectral domain optic coherence tomography (SD-OCT) in asymptomatic empty sella (ES) patients.Materials and methods: In this cross-sectional, non-randomized prospective study, 44 ES patients and 74 age- and sex-matched healthy individuals were evaluated. All the patients and controls competed an automated 30-2 visual field (VF) test. The mean deviation (MD), pattern standard deviation (PSD), RNFL, and GCL + thickness values obtained with SD-OCT were compared statistically between the two groups.Results: No marked VF defects were found in either group, and there was no statistically significant between-group difference in MD or PSD values. In terms of RNFL thickness, the average and superior quadrant RNFL values of the ES patients were thinner than those of the controls, with statistical significance (p = 0.013 and p = 0.043, respectively). Although other measured RNFL quadrant thicknesses and foveal thickness (FT), macular volume (MV), and average macular thickness (AMT) values were reduced in the ES group, these differences were not statistically significant. The average GCL + value and GCL + values in six sectors in the patient group were significantly lower than those in the control group.Conclusions: Asymptomatic ES patients have a risk of primary ES syndrome and should be followed up using a multidisciplinary approach. Objective and quantitative RNFL and GCL + thickness measurements obtained with OCT can provide valuable data for monitoring these patients.