Optic nerve compression by normal carotid artery in patients with normal tension glaucoma

Management of patients with a neurovascular conflict involving the optic nerve and a non-diseased intracranial artery: Three cases

Introduction

Determining whether a neurovascular conflict (NVC) involving the anterior visual pathway (AVP) and a non-diseased intracranial artery is amenable for microvascular decompression is challenging. Moreover, it is unclear whether microvascular decompression of the optic nerve is an effective therapy.

Research question

What are the outcomes of different treatment strategies for NVCs involving the AVP and a non-diseased intracranial artery?

Material and methods

Data on patients with symptomatic NVCs involving the AVP and a non-diseased intracranial artery was collected and included treatment and outcome parameters. The case series was drafted in accordance with the CARE guidelines.

Results

Three patients aged 53,53 and 55 visited our out-patient clinic with a suspected symptomatic NVC between the optic nerve and a non-diseased intracranial artery. A conservative treatment was opted for in the first patient aimed at treating her glaucoma, with temporary improvement of symptoms. Microvascular decompression of the optic nerve was performed in two patients. One operated patient developed post-operative complications resulting in posterior circulation perfusion decline, while the other experienced a worse tunnel vision with a decrease in visual acuity.

Discussion and conclusion

The diagnosis of a symptomatic NVC between the AVP and a non-diseased intracranial artery should be considered with caution, i.e. after exclusion of all other causes. Microvascular decompression can be performed but does not necessarily improve symptoms. A better understanding of the pathophysiological mechanisms underlying these NVCs is warranted to determine the benefit of microvascular decompression of the optic nerve.

Supraclinoid Internal Carotid Artery Dolichoectasia Causing Compression of the Prechiasmatic Optic Nerve

BACKGROUND AND IMPORTANCE

Intracranial arterial dolichoectasia (or dilatative arteriopathy) is characterized by abnormal elongation, tortuosity, or increase in diameter of at least one of the main cerebral vessels. Dolichoectasia can be found incidentally or can present with cranial neuropathies (including vision loss) or stroke. Here, we describe the presentation and open surgical treatment of a patient with dolichoectasia of the intracranial internal carotid artery (ICA) causing monocular vision loss.

CLINICAL PRESENTATION

A 73-year-old man presented with several months of progressive monocular vision loss and was found to have dolichoectasia of the supraclinoid ICA and subsequently underwent microsurgical decompression of the overlying affected optic nerve. The patient's postoperative convalescence was uncomplicated, and he had improvement in his right-sided monocular vision loss after surgery.

CONCLUSION

We present the case of a patient with dolichoectasia of the supraclinoid ICA causing compression of the optic nerve with resultant monocular vision loss. Timely microvascular decompression proves to be an effective technique for vision preservation in the setting of this rare pathologic entity.

Neuro-Ophthalmological Optic Nerve Cupping: An Overview

Optic nerve cupping or enlargement of the cup-to-disc ratio is widely recognized as a feature of glaucoma, however it may also occur in non-glaucomatous optic neuropathies. The most well-recognized non-glaucomatous optic neuropathies that cause cupping include compressive optic neuropathies, arteritic anterior ischemic optic neuropathies, hereditary optic neuropathies, and optic neuritis. Cupping is thought to consist of two main components: prelaminar and laminar thinning. The former is a shallow form of cupping and related to loss of retinal ganglion cells, whereas the latter involves damage to the lamina cribrosa and peripapillary scleral connective tissue. Differentiating glaucomatous and non-glaucomatous optic nerve cupping remains challenging even for experienced observers. Classically, the optic nerve in non-glaucomatous causes has pallor of the neuroretinal rim, but the optic nerve should not be examined in isolation. The patient’s medical history, history of presenting illness, visual function (visual acuity, color vision and visual field testing) and ocular examination also need to be considered. Ancillary testing such as optical coherence tomography of the retinal nerve fiber layer and ganglion cell layer-inner plexiform layer may also be helpful in localizing the disease. In this review, we review the non-glaucomatous causes of cupping and provide an approach to evaluating a patient that presents with an enlarged cup-to-disc ratio.

Optic Disc Cupping Due to Dolichoectatic Internal Carotid Artery Optic Nerve Compression

BACKGROUND

To determine whether significant compression of the optic nerve by the internal carotid artery (ICA) can produce an optic neuropathy with optic disc cupping that resembles glaucoma in patients without elevated intraocular pressure (IOP).

METHODS

This was a retrospective case series of patients referred to neuro-ophthalmology for a possible nonglaucomatous optic neuropathy. Patients were included in the study if they had preserved visual acuity, optic disc-related visual field defects, optic nerve cupping, IOP less than 21 mm Hg, open angles, and unequivocal radiological compression of the ipsilateral optic nerve by an intracranial blood vessel.

RESULTS

Three patients were included with a mean age of 56.3 (range 29-82) years. Patient 1 was a 58-year-old man incidentally noted to have left optic nerve cupping on a routine examination. He had an inferior arcuate defect and the left prechiasmatic optic nerve was elevated and compressed by a tortuous left ICA. Patient 2 was a 29-year-old man with a normal-tension glaucoma (NTG) diagnosis for 7 years in the right eye treated with latanoprost. He had a superior greater than inferior arcuate defect and there was vascular compression of the optic nerve between the supraclinoid ICA and A1 segment of the anterior cerebral artery. Patient 3 was an 82-year-old woman with an NTG diagnosis for 10 years who had progression of her visual field defects despite low IOPs. MRI showed mass effect on the right optic nerve by a dolichoectatic right supraclinoid ICA.

CONCLUSIONS

Significant compression of the optic nerve by a normal, tortuous, or dolichoectatic ICA may result in an optic neuropathy with optic disc cupping that resembles glaucoma.

Differentiation of compressive from glaucomatous optic neuropathy with spectral-domain optical coherence tomography

PURPOSE

To compare optic disc topography in eyes with compressive optic neuropathy (CON) and open-angle glaucoma (OAG) using spectral-domain (SD) optical coherence tomography (OCT) and Heidelberg retinal tomograph (HRT) (Heidelberg Engineering GmbH, Heidelberg, Germany).

DESIGN

Cross-sectional, observational study.

PARTICIPANTS

A total of 200 eyes from 123 patients with CON (69 eyes) or OAG (58 eyes) and controls (73 eyes).

METHODS

Univariate and multivariate analyses of HRT parameters, SD-OCT circumpapillary retinal nerve fiber layer (RNFL) thickness, and optic nerve head (ONH) parameters.

MAIN OUTCOME MEASURES

Circumpapillary RNFL, OCT ONH parameters, and HRT parameters.

RESULTS

The univariate analysis of OCT parameters demonstrated significant differences between the temporal and nasal quadrants; clock hours 3 (55 vs. 73 μm), 4, 8 (93.9 vs. 70.7 μm), 9, and 10; vertical cup-to-disc ratio (C:D) (0.6 vs. 0.8) and cup volume (0.2 vs. 0.5) (P<0.001) between patients with CON and OAG, respectively. The CON discs were significantly different from normal discs for all OCT parameters except cup volume. The CON discs were not significantly different from normal discs for HRT parameters, except for mean RNFL thickness and cup shape measure. The OAG discs were significantly different from normal discs in all HRT and OCT parameters (P<0.001). Multivariate analysis demonstrated that the OCT 3 o'clock temporal sector, average C:D ratio, vertical C:D ratio, and cup volume measurements were able to differentiate OAG from CON.

CONCLUSIONS

Compressive optic neuropathy is associated with significantly thinner nasal and temporal sectors compared with OAG, whereas OAG results in larger cups and cup volume with OCT measurements. The Heidelberg retinal tomograph is not able to differentiate CON from normal discs.

Glaucoma-like optic neuropathy in patients with intracranial tumours

PURPOSE

To examine frequency and associated factors of glaucoma-like appearance of the optic nerve head in patients with intrasellar, suprasellar or parasellar tumours.

METHODS

This retrospective clinical observational study included patients who were consecutively treated for intrasellar tumours (n = 143), suprasellar tumours (n = 321), parasellar tumours (n = 36) or retrosellar tumour (n = 1), and all of whom had undergone fundus photography and full-threshold visual field examination. The tumour spectrum included 336 pituitary gland tumours, 32 meningiomas, 89 craniopharyngiomas, 9 chiasmal gliomas and 35 other types of tumours or lesions. An age-matched control group was formed from the population-based Beijing Eye Study. Using fundus photographs and visual field examinations, glaucoma was defined by a neuroretinal rim shape not following the ISNT rule (Disc glaucoma group) and by an abnormal rim shape plus glaucoma-like visual field defects (Field glaucoma group). Type and size of the tumours were assessed on neuroradiological images.

RESULTS

Five-hundred and one patients fulfilled the inclusion criteria. Disc glaucoma and Field glaucoma were detected significantly more frequently in the study population [34 (6.8%) patients and 31 (6.3%) patients, respectively] than in the population-based control group of the same ethnicity (1.3% ± 0.5%; p < 0.001). In multivariate analysis, presence of Disc glaucoma [odds ratio (OR) = 2.64; p = 0.016] and presence of Field glaucoma (OR = 3.01; p = 0.027) were significantly associated with tumour location [suprasellar > parasellar > intrasellar]. The same held true for tumour width (OR = 1.08; p = 0.002; and OR = 1.08; p = 0.003, respectively).

CONCLUSIONS

Large perisellar tumours were associated with a glaucoma-like appearance of the optic nerve head in eyes. It may diagnostically and pathogenetically be of importance.

Tarsal tunnel syndrome associated with a pulsating artery: effectiveness of high-resolution ultrasound in diagnosing tarsal tunnel syndrome

We describe a patient with tarsal tunnel syndrome in whom ultrasound imaging revealed compression of the posterior tibial nerve by a pulsating artery. High-resolution ultrasound showed a round pulsating hypoechoic lesion in contact with the posterior tibial nerve. Ultrasound-guided injection of 0.5% lidocaine temporarily resolved the paresthesia. These findings suggest an arterial etiology of tarsal tunnel syndrome.

Neuro-ophthalmic manifestations of a complicated cholesteatoma

BACKGROUND

A cholesteatoma, also known as an epithelioma, is a mass of soft tissue that results from the accumulation of keratin protein debris enclosed by a layer of stratified squamous epithelium.

CASE REPORT

A patient with cholesteatoma surrounding both internal carotid arteries presented with cerebral ischemic symptoms expressed as visual and ocular symptoms. Because of its location, mass effect, and potential stenosis of the internal carotids, this slow-growing tumor is potentially sight threatening. Asymmetric cupping of the optic nerves associated with symptoms such as dizziness, diplopia, or facial pain should be worked up carefully.

CONCLUSION

The primary care optometrist can play an important role in the diagnosis and continued management of a patient with a cholesteatoma, carefully monitoring early signs of progression or change. This case illustrates how an intracranial lesion, away from the eye, can impact a number of ocular and visual functions.

Optociliary Shunt Vessels in Compressive Optic Neuropathy by the Intracranial Internal Carotid Artery

Purpose

To report a clinical case of optic nerve compression by supraclinoidal internal carotid artery associated with optociliary shunt vessels.

Methods

A 78-year-old woman with the clinical triad of left visual loss, ipsilateral optic disc pallor, and retinochoroidal (optociliary) shunt vessels is reported. She complained of loss of vision in the left eye of 2 years' duration.

Results

A diffuse depression of the visual field was found in the affected eye. Magnetic resonance imaging revealed left optic nerve compression by the supraclinoidal internal carotid artery.

Conclusions

The occurrence of optociliary shunt vessels, visual loss, and optic atrophy is a non-specific sign of chronic optic nerve compression and in some instances may be falsely localized.

Optic nerve hyperintensity on T2-weighted images among patients with pituitary macroadenoma: correlation with visual impairment

PURPOSE

Visual acuity (VA) disturbance other than field defect is important in evaluating patients with pituitary macroadenoma. The purpose of this study was to evaluate MR imaging appearances of optic nerves in patients with pituitary macroadenoma and to ascertain whether visual impairment was correlated with abnormality in optic nerve signal intensity.

PATIENTS AND METHODS

Twenty-seven patients with pituitary macroadenoma were examined. Optic nerves were evaluated on T2-weighted images and correlations of signal intensity abnormality with VA disturbance, visual field disturbance, degree of optic chiasm compression, pathologic findings of surgical specimen, and disease duration were statistically analyzed. Correlations between recovery of VA after treatment and the above-mentioned factors were also determined.

RESULTS

Coronal T2-weighted images demonstrated unilateral optic nerve hyperintensity lesions in 9 patients. Bilateral signal intensity abnormality of the optic nerve was seen in 5 patients. Signal intensity abnormality of the optic nerve was seen at the site of compression and in the ventral side of the tumor. These patients did not demonstrate signal intensity abnormality posterior to the tumor. Presence of such signal intensity abnormalities was correlated with the degree of optic chiasmal compression and with VA disturbance. Recovery of VA after treatment was correlated with disease duration.

CONCLUSION

Hyperintensity of the optic nerves ventral to the pituitary macroadenoma was associated with VA impairment. Recovery of VA after treatment was correlated with disease duration. MR imaging of the optic nerves can provide valuable information for management of pituitary macroadenoma.