The Road To Retrograde Recovery

The Road To Retrograde Recovery
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INTRODUCTION

Welcome to the “Neuro Nuggets” column within the Journal of Medical Optometry!  This column aims to make neuro-ophthalmic disease more approachable by blending real-world clinical cases with evidence-based medicine.  The patient in this edition’s column offers an opportunity for clinicians to gain novel clinical pearls from a familiar disease process.  Enjoy!

 

CASE PRESENTATION

A 67 year-old black male presented for evaluation complaining of difficulty reading and blur in the temporal aspect of the right visual field over the preceding three months. The patient’s past medical history included chronic ischemic heart disease, hypertension, and type 2 diabetes mellitus.

On examination, the patient’s best-corrected visual acuity was 20/25 in the right eye and 20/20 in the left eye. During vision testing, it was noted that the patient had difficulty reading letters located in the temporal visual field of the right eye.  Color vision by Ishihara was intact in each eye. Red cap desaturation testing showed relative 10% desaturation in the right eye compared to the left eye.  Ocular motility evaluation was normal. Confrontation visual field testing demonstrated temporal constriction of the visual field of each eye. Slit lamp exam, intraocular pressure, and dilated fundus evaluation were normal in each eye. The neuro-retinal rim of the optic disc was felt to be pink and intact without significant optic disc pallor or atrophy in either eye (Figure 1).

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Figure 1. Optic disc fundus photos at presentation.

 

Automated visual field testing revealed a bitemporal hemianopsia. Ocular coherence tomography (OCT) showed largely intact peripapillary retinal nerve fiber layer (pRNFL) thickness in each eye with a few sectors flagged borderline thin (Figure 2), but there was notable binasal attenuation of the ganglion cell layer (GCL) on macular posterior pole OCT imaging (Figure 3).

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Figure 2. Retinal Nerve Fiber Layer (RNFL) scan at presentation. Note few sectors of mild RNFL borderline thinning in each eye.

 

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Figure 3. Macular Ganglion Cell Layer (GCL) segmentation at presentation. Note binasal GCL thinning.

 

Magnetic resonance imaging (MRI) of the brain with/without contrast revealed a pituitary lesion measuring up to 1.9 cm in size that was resulting in chiasmal compression but with no definitive radiologic evidence of invasion into the sinuses (Figure 4). Endocrine serologic testing demonstrated normal pituitary function.

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Figure 4. MRI brain T2 coronal images before (A) and after (B) resection of the pituitary mass.

The patient was diagnosed with a non-functioning pituitary macroadenoma and underwent trans-sphenoidal resection of the lesion. There were no major surgical complications, but the operative note did mention a small arachnoid tear occurred intra-operatively during exploration of the anterior sellar floor which resulted in cerebrospinal fluid (CSF) leakage. Pathology studies confirmed that the tumor was a pituitary adenoma.

Visual field recovery began shortly after surgical removal of the pituitary tumor (Figure 5). The binasal OCT GCL attenuation persisted and remained stable.  Of note, there was an incidental discovery of bilateral peripapillary retinal fluid accumulation (vs retinoschisis) that was found on OCT imaging one month after pituitary resection which subsequently resolved by two months post-op (Figure 6). At the time of writing, the patient has been followed for 8 years after initial evaluation and remained clinically stable with intact neuro-ophthalmic parameters over that time.

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Figure 5. Serial visual field examinations from presentation to 8 years after trans-sphenoidal resection of the pituitary tumor. POM = post-op month.

 

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Figure 6. Serial macular OCT imaging. Note presence of intraretinal fluid vs retinoschisis within the peripapillary area in each eye at POM#1 that subsequently resolved by POM#2. POM = post-op month.

DISCUSSION

Enlarging pituitary tumors elevate and splay the optic chiasm. This results in widening and flattening of the optic chiasm as well as stretching of the axons responsible for visual function. Ophthalmic literature suggests that the anterior optic nerves (proximal to the chiasm) act as anchors for the optic chiasm, preventing it from moving out of the way from growing pituitary tumors; the optic tracts (distal to the chiasm) are thought to be more mobile and capable of moving further away from the tumor.1 Assuming normal chiasm position (i.e. not pre-fixed or post-fixed), the result is that the anterior and middle optic chiasm are subject to greater compression and distortion from underlying pituitary tumors.1

Modern neuro-ophthalmic evaluation of patients with sellar or parasellar lesions should include OCT imaging of the optic nerve and macula.2 Retrograde degeneration of the ganglion cell layer may be helpful to determine chronicity of visual pathway damage from sellar lesions and assists with guiding discussion around prognosis for recovery.3 Notably, retrograde degeneration takes time to occur and may not become evident on OCT GCL imaging until several months after the initial lesion has formed.4,5

Visual recovery following pituitary tumor removal often follows chiasmal decompression. Early decompression is recommended to maximize the chance for visual recovery.6 Vision can begin to recover as soon as hours or days after surgical removal.7 Surgical resection of pituitary tumors is thought to remove conduction block, allow remyelination, and restore axoplasmic flow.1 Unfortunately optic atrophy is not felt to be reversible, however, there may be discordance between OCT imaging and visual field results.3 As in this case, patients may demonstrate visual recovery on automated perimetry despite persisting GCL attenuation. The retinal ganglion cells are thought to have poor regenerative properties8 so once GCL thinning appears on OCT imaging it is unlikely to improve.

Of particular interest in this case is the nature of the retinal fluid accumulation (vs peripapillary retinoschisis) that transiently appeared shortly after pituitary resection surgery and subsequently self-resolved. One can draw an analogy to optic disc pit maculopathy in which some authors propose that the retinal fluid accumulation is due to accumulation of cerebrospinal fluid, stemming from the subarachnoid space around the optic nerve meningeal covering.9-11 Since this patient had a CSF leak at the time of surgery, it is possible the peripapillary retinal fluid represents CSF accumulation that ultimately reabsorbed without need for ophthalmic intervention or significant impact on visual function.

 

CLINICAL PEARLS

  • Earlier intervention may be key to maximize the opportunity for visual recovery in patients with visual field loss stemming from pituitary lesions and chiasmal compression
  • Presence of retinal fluid accumulation or a retinoschisis-like appearance in the peripapillary space may represent accumulation of CSF following pituitary resection
  • Optical coherence tomography may help to guide discussion surrounding prognosis for visual recovery in patients with pituitary tumors considering surgical intervention
  • Visual recovery following management of pituitary tumors is thought to begin soon after the lesion is debulked

 

REFERENCES

  1. Horton et al. Decussating axons segregate within the anterior core of the primate optic chiasm. British Journal of Ophthalmology. 2023. 107, 447-452. DOI: 10.1136/bjo-2022-322235
  2. Banc et al. Ocular Optical Coherence Tomography in the Evaluation of Sellar and Parasellar Masses: A Review. Neurosurgery. 2023. 92:1, 42-67. DOI: 10.1227/neu.0000000000002186
  3. Lo et al. Recent advances and future directions on the use of optical coherence tomography in neuro-ophthalmology. Taiwan J Ophthalmol. 2021. 11:1, 3-15. DOI: 10.4103/tjo.tjo_76_20
  4. Mitchell et al. Corresponding Ganglion Cell Atrophy in Patients With Postgeniculate Homonymous Visual Field Loss. J Neuroophthalmol. 2015. 35:4, 353-9. DOI: 10.1097/WNO.0000000000000268.
  5. Dinkin M. Trans-synaptic Retrograde Degeneration in the Human Visual System: Slow, Silent, and Real. Curr Neurol Neurosci Rep. 2017. 17:16. DOI: 10.1007/s11910-017-0725-2.
  6. Yoneoka et al. Early morphological recovery of the optic chiasm is associated with excellent visual outcome in patients with compressive chiasmal syndrome caused by pituitary tumors. Neurol Res. 2015. 37:1, 1-8. DOI: 10.1179/1743132814Y.0000000407
  7. Horton, Jonathan. Invited Commentary: Ganglion Cell Complex Measurement in Compressive Optic Neuropathy. Journal of Neuro-Ophthalmology. 2017. 37:1, 13-15. DOI: 10.1097/WNO.0000000000000489
  8. So et al. Regenerative capacity of retinal ganglion cells in mammals. Vision Res. 1998. 38:10, 1525-35. DOI: 10.1016/s0042-6989(97)00226-5.
  9. Iyer et al. Optic Pit Maculopathy: Clinical Features and Management Options. Curr Ophthalmol Rep. 2021. 9:4, 158-167. DOI: 10.1007/s40135-021-00274-0
  10. Gowdar et al. An Insight Into the Pathogenesis of Optic Disc Pit–Associated Maculopathy With Enhanced Depth Imaging. JAMA Ophthalmol. 2015. 133:4, 466–469. DOI:10.1001/jamaophthalmol.2014.6093
  11. Krivoy et al. Imaging congenital optic disc pits and associated maculopathy using optical coherence tomography. Arch Ophthalmol. 1996. 114:2, 165-70. DOI: 10.1001/archopht.1996.01100130159008

 

The author has no financial disclosures, and no sponsorship or funding was involved in this work.  Special acknowledgment to Emily Carell OD and Kathryn Matherly OD who were both instrumental in the diagnosis and early management of this patient.

Boston VA Healthcare System | Boston, MA

Dr. Kane graduated from New England College of Optometry in 2015 and went on to complete an ocular disease/primary care residency at VA Boston Jamaica Plain from 2015-2016. He is currently an attending optometrist at VA Boston. His interests include clinical teaching, neuro-ophthalmic disease, retinal vascular disease, glaucoma, and ocular manifestations of systemic disease.

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