Assessment the neurodegenaration process of post-geniculate optic pathway in thalamic tumors using optical coherence tomography: Post-geniculate optic pathway in thalamic tumors

PURPOSE

To investigate the effect of thalamic tumors related to post-geniculate optic pathway and those of microsurgical removal on neurodegeneration process of visual pathway using OCT.

METHODS

This cross-sectional study included 30 eyes of 15 patients with thalamic tumors and data compiled from 45 eyes of 45 healthy participants. The analysis of variables was divided into ipsilateral and contralateral eye depends on the laterality of brain tumors. The data gained at baseline, postoperative 3rd and postoperative 6th month period was analyzed in One-Way Repeated Measures ANOVA.

RESULTS

The mean superior quadrant retinal nerve fiber layer (RNFL) thickness of ipsilateral eye was significantly thicker (p = 0.02), while inferior hemifield ganglion cell-inner plexiform layer (GC-IPL) thickness of contralateral eye was significantly higher compared to control groups (p = 0.02). Significant negative correlations were found between the mean preop. mean deviation (MD) and tumor volume and time interval between initial diagnosis and surgery (r = - 0.730, p = 0.002 and r = - 0.680, p = 0.005, respectively) in the ipsilateral eye. In repeated measure analysis, there was no unfavourable effect of thalamic microsurgery on peripapillary average RNFL thickness on both ipsilateral and contralateral eyes (Ipsilateral eye; f (1.5,21.7) 0.76 p = 0.51 and contralateral eye; f (1.4,20.4) 0.42 p = 0.59).

CONCLUSION

This study suggests that thalamic tumors affecting post-geniculate optic pathway may lead to significant increase in RNFL and GC-IPL thicknesses and changes in VF parameters. Timely intervention in thalamic tumors may prevent irreversible loss of retinal axons secondary to neurodegeneration process.

Machine learning in neuroimaging: from research to clinical practice

Neuroimaging is critical in clinical care and research, enabling us to investigate the brain in health and disease. There is a complex link between the brain's morphological structure, physiological architecture, and the corresponding imaging characteristics. The shape, function, and relationships between various brain areas change during development and throughout life, disease, and recovery. Like few other areas, neuroimaging benefits from advanced analysis techniques to fully exploit imaging data for studying the brain and its function. Recently, machine learning has started to contribute (a) to anatomical measurements, detection, segmentation, and quantification of lesions and disease patterns, (b) to the rapid identification of acute conditions such as stroke, or (c) to the tracking of imaging changes over time. As our ability to image and analyze the brain advances, so does our understanding of its intricate relationships and their role in therapeutic decision-making. Here, we review the current state of the art in using machine learning techniques to exploit neuroimaging data for clinical care and research, providing an overview of clinical applications and their contribution to fundamental computational neuroscience.

Unilateral papilledema in idiopathic intracranial hypertension: A rare entity

Idiopathic Intracranial Hypertension (IIH), also known as pseudotumor cerebri is a clinical syndrome of unknown etiology, which typically affects young, obese women of childbearing age and is characterized by increased intracranial pressure and bilateral papilledema. Unilateral and highly asymmetrical papilledema is a rare presentation in IIH occurring in less than 4% of patients with definite IIH and can poses a diagnostic challenge for the treating physician as it usually raises the suspicion of localized ocular pathology. As per current consensus, papilledema results in stasis of axoplasmic transport due to mechanical compression, leading to secondary vascular changes of venous dilation and hemorrhage. Given this mechanism, the underlying reasons for unilateral and asymmetrical papilledema remain unclear.

Complete bilateral ophthalmoplegia in malignant intracranial hypertension in a child

PURPOSE

To describe a case of fulminant idiopathic intracranial hypertension (IIH) in a child with "malignant" presentation.

CASE REPORT

A 16-year-old, previously healthy, girl presented with bilateral visual loss and bilateral global limitation of eye movements in the absence of headache. Extensive laboratory evaluation for infectious, inflammatory, autoimmune, and neoplastic conditions was negative. Magnetic resonance imaging (MRI) of the brain and lumbar puncture findings were consistent with a diagnosis of IIH. Extraocular motility improved in the next few days as well as optic disc edema but visual acuity remained poor.

CONCLUSION

The authors believe that the acute, severe, and fulminant ("malignant") presentation with markedly elevated intracranial pressure may produce the unique presentation of severe vision loss and bilateral complete ophthalmoplegia. Interestingly, there was no headache. To our knowledge this is the first such case to be reported in the English language ophthalmic literature.

Estimation and interrater reliability of pupillography by digital mobile app: Digital movil pupillography app validity

OBJECTIVE

The examination of pupillary light reflexes is widely employed to evaluate the autonomic system's balance, ocular, and neurological conditions, typically evaluated by qualitative observation. To describe and evaluate the inter-rater reliability and agreement of pupillometric values obtained with a novel semi-automatic mobile pupillography app.

METHODS

Two examiners and two graders perform the measurements with an android app which corrects the device-face distance, measure the maximum contraction of the pupil, and calculates its slope, in a hospital room setting with three levels of environmental light intensity: <100, 101 to 200, and 201 to 300 lux, at 200, 400, 600, 900, 1200, and 1500 milliseconds.

RESULTS

Sixty healthy individuals, aged 18 to 45, were included; 85% had brown eyes. The reliability of the pupil/iris ratio had Ri = 70% to 88%, and bland Altman graphics show a uniform agreement. The pupillography curves show a similar slope at different light intensities, during the contraction phase.

CONCLUSION

There were very good repeatability and inter-rater reproducibility of the measurements at average levels of illumination in examination rooms, even in dark-eyed people. This app provides a highly promising approach to pupillary measurements in clinical practice.

Direct and transsynaptic retrograde degeneration and optic nerve head microvascular changes in patients with hemianopia

PURPOSE

To investigate optic nerve head (ONH) microvascular changes secondary to transsynaptic retrograde degeneration (TRD), comperatively with direct retrograde degeneration and healthy controls.

METHODS

Patients with hemianopia due to intracranial lesion included in the study. Intracranial lesion was categorized by location: postgeniculate (causing TRD), chiasmal (causing direct retrograde degeneration). For the postgeniculate lesions, the eye on the same side of the lesion was defined as the ipsilateral eye and the eye on the opposite side as the contralateral eye. Optic disc microvasculature was evaluated with the help of optic coherence tomography angiography.

RESULTS

Sixteen eyes of 16 patients with chiasmal lesion, 28 eyes of 14 patients with postgeniculate lesion, and 30 eyes of 30 healthy subjects were included in the study. Ipsilateral eyes of the patients with postgeniculate lesion had decreased vessel density at the temporal sectors compatible with the affected nasal side of the visual field. Contralateral eyes showed no reduction of the vessel density at the affected nasal sectors. The eyes with chiasmal lesions had decreased vessel density at the peripapillary region and nasal half of the ONH compatible with temporal hemianopia. Vascular changes in the chiasmal lesion were more prominent than those of the postgeniculate lesion. Retinal nerve fiber layer and ganglion cell complex thickness were reduced.

CONCLUSION

Vessel density of ONH was reduced in patients with homonymous hemianopia, providing evidence for TRD secondary to acquired postgeniculate lesion. Direct retrograde degeneration was more prominent in affected sectors when compared to TRD.

Vascular changes with optical coherence tomography angiography during aura of migraine: A case report

PURPOSE

To demonstrate macular and optic disk vessel changes by optical coherence tomography angiography during and after a migraine attack with aura.

METHODS

Case report.

RESULTS

A 34-year-old healthy female patient was evaluated by optical coherence tomography angiography imaging during visual aura with phosphenes in the left visual field. Optical coherence tomography angiography imaging showed diffuse narrowing of the retinal vessels, decreased radial peripapillary capillary density, and decreased superficial and deep foveal vessel density in the right eye. These changes improved 3 hours after visual aura. The patient suffered from right eye pain and right-sided headache, which are typical for migraine, after the visual aura.

CONCLUSION

These findings indicate that blood flow during migraine attack is reduced not only in the brain but also in the eye. Eye pain in migraine patients may be due to decreased blood flow in the eye. Restoring the vascular changes 3 hours after the visual aura suggests that vascular changes may be transient during a migraine attack.