Junctional Scotoma From Self-Inflicted Transnasal Penetrating Foreign Body

doi: 10.62055/zgpywnqjfsat

INTRODUCTION

Welcome to the “Neuro Nuggets” column within the Journal of Medical Optometry (JoMO)! 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 features a characteristic visual field defect with a unique mechanism of injury. Enjoy!

CASE PRESENTATION

A 62-year-old white male presented for initial evaluation without any acute ocular or visual concerns. The patient’s past medical history included chronic alcohol use, paranoid schizophrenia vs bipolar disorder, and remote history of “stroke” with resultant right-sided weakness.

On examination, the patient’s best-corrected visual acuity was 20/25 in each eye. Color vision by Ishihara was reduced in each eye, reportedly longstanding and congenital. Ocular motility evaluation and ocular alignment evaluation were both normal in each eye. Pupil testing demonstrated bilaterally sluggish reaction to light with a mild to moderate relative afferent pupillary defect (RAPD) in the left eye. Red cap desaturation testing revealed relative 20% desaturation in the left eye compared to the right eye. Slit lamp exam was within normal limits aside from age-appropriate nuclear sclerotic cataracts in each eye. On dilated fundus examination, the optic nerve heads were bilaterally pale (left eye worse than right eye), and the retinal exam was unrevealing.

Spectral domain optical coherence tomography (SD-OCT) demonstrated significant thinning in the temporal and nasal sectors of the peripapillary retinal nerve fiber layer (pRNFL) for the right eye and diffuse pRNFL thinning in the left eye; the global pRNFL thickness was 62 microns in the right eye and 41 microns in the left eye (Figure 1). Macular ganglion cell layer OCT segmentation showed vertically-respecting nasal thinning in the right eye and diffuse decimation in the left eye (Figure 1). Automated perimetry revealed a temporal hemianopic visual field defect in the right eye (mean deviation -14.54 dB) and significant diffuse loss in the left eye (-30.08 dB) (Figure 2).

 

 

 

Due to the clinical concern for a bilateral, asymmetric optic neuropathy and perimetric testing suggesting an optic nerve and/or chiasm lesion, the patient was advised to undergo urgent neuroimaging. Magnetic resonance imaging (MRI) was contraindicated due to a metallic penile implant, so computed tomography (CT) imaging of the head/brain was obtained. The head CT did not show any pituitary mass lesion, but it did reveal left-sided anatomical changes and stigmata suggestive of prior left craniotomy (Figure 3).

 

 

Upon further questioning, the patient revealed that he intentionally inserted a pencil far up his nose as a suicide attempt while he was incarcerated over 20 years prior to presentation. The foreign body extended into the intracranial space and necessitated neurosurgical removal. Unfortunately, his post-operative course was complicated by a left-sided cerebrovascular accident that resulted in chronic right-sided hemiparesis and speech deficits. The patient’s self-inflicted penetrating injury was felt to account for the visual deficits, presumably from damage to the left optic nerve and optic chiasm.

DISCUSSION

Localizing lesions to the optic chiasm and sellar region is possible using clinical exam data and ancillary testing such as automated perimetry and optical coherence tomography (OCT). Ganglion cell axonal fibers originating from the nasal retina (carrying temporal visual field information) cross in the optic chiasm and are susceptible to damage from underlying pituitary mass lesions or trauma.  The patient in this case report presented with bilateral optic disc pallor and visual field loss following a self-inflicted penetrating transnasal injury with a pencil.  The temporal visual field loss with nasal ganglion cell layer (GCL) thinning on OCT in the right eye along with the diffuse visual loss and GCL thinning in the left eye were helpful in suggesting damage to the left optic nerve and the anterior optic chiasm. Additionally, the diffuse visual field loss in the left eye and temporal visual field loss in the right eye resulted in a characteristic visual field defect – the so-called “junctional scotoma.”¹ This visual field pattern is clinically useful as it specifically localizes the lesion to the “junction” where the optic nerve and anterior optic chiasm meet, typically with visual loss greatest on the side where the optic nerve is impacted. The nasal ganglion cell loss in the right eye can likely be accounted for by retrograde degeneration of the nasal ganglion cell axons in the right eye stemming from optic chiasmal damage, while the left optic nerve was probably more severely (or directly) injured resulting in diffuse GCL decimation.

Traumatic optic chiasmal syndromes are rare due to the “anatomic privilege” of the optic chiasm, situated in an area in the brain that is usually sequestered from damage.² In the absence of penetrating injury, significant trauma (often from motor vehicle accidents or severe falls) can also produce optic chiasm damage.² The mechanisms of traumatic optic chiasm damage are thought to involve mechanical injury to crossing axons, axonal or vascular shearing, compression from associated perichiasmal hemorrhage or edema, or ischemia from vascular disruption.^3,4

Self-inflicted ocular and intracranial injuries have been associated with psychiatric illness, suicide attempts, drug or alcohol-related psychosis, and ritualistic behavior.⁵ Numerous different objects have been described in patients with penetrating transnasal or transorbital injuries including pens or pencils,^6-10 metallic rods,¹¹ chopsticks,¹² toothbrush,¹³ wire hanger,¹⁴ and even glasses temples.¹⁵ Damage to surrounding anatomy from transnasal penetrating foreign body injuries may result in epistaxis, cerebrospinal fluid (CSF) leaks, seizure, internal carotid artery injury, pituitary gland compromise, and other neurologic complications that can be fatal.⁶ Management often involves a multi-disciplinary approach often with neurosurgery and ear, nose, and throat providers, often with surgical removal of the foreign body, consideration of broad-spectrum antibiotic coverage, and psychiatric evaluation for self-inflicted injuries.^6,7,16

There have been multiple case reports of patients sustaining neuro-ophthalmic complications from penetrating foreign body injuries. Nguyen et al described a case of a 56-year-old female with a history of alcohol abuse and depression who inserted a ballpoint pen through her left nostril and presented with multiple cranial nerve palsies attributed to injury at the right superior orbital fissure and cavernous sinus; the cranial nerve palsies persisted despite surgical removal of the foreign body.⁶ Singh et al published a case report of a 44-year-old male who sustained a penetrating metallic foreign body injury during a factory accident; the foreign body entered the brain through the right eye and orbit, resulting in severe visual loss and chiasmal damage.¹¹ Younis et al documented a 67-year-old male who presented with a wooden stick foreign body through the left nostril after a fall that resulted in unilateral blindness in the right eye, attributed to oblique insertion of the nasally penetrating foreign body damaging the optic nerve in the region of the right optic canal.¹⁷ The close anatomic relationship between the optic nerve and paranasal sinuses is believed to render the optic nerve susceptible to injury in situations of sinus trauma or surgery.¹⁷ Depending on the nature and trajectory of the injury, it is also possible for patients who sustain penetrating orbital injuries to avoid any major long-term complications.^18,19

The case presented here is unique in that the visual field defect was highly suggestive of optic nerve and chiasm damage. The transnasal route of injury in this case is similar to the route of pituitary tumor surgical removal (i.e. transsphenoidal). To the best of our knowledge, this may be the first published case of transnasal penetrating foreign body injury that resulted in a junctional scotoma.

CLINICAL PEARLS:

● Junctional scotoma often results from lesions impacting the pre-chiasmal optic nerve and adjacent optic chiasm
● Transnasal penetrating foreign bodies carry a high likelihood of intracranial injury and potential neuro-ophthalmic manifestations
● Neuroimaging may appear normal even in patients with significant visual loss from trauma to the optic chiasm

 

REFERENCES

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3. Hassan A, Crompton JL, Sandhu A. Traumatic chiasmal syndrome: a series of 19 patients. Clin Exp Ophthalmol. 2002 Aug;30(4):273-80. doi: 10.1046/j.1442-9071.2002.00534.x.

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16. Hansen MU, Thorsberger M, Jørgensen JS, von Buchwald C. Penetrating Orbital Sphenoid Sinus Trauma with a Wooden Stick: A Challenging Case Report. Case Rep Ophthalmol. 2020 Oct 29;11(3):540-545. doi: 10.1159/000510019.

17. Younis R, Berkowitz E, Shreter R, Kesler A, Braverman I. Traumatic Optic Neuropathy and Monocular Blindness following Transnasal Penetrating Optic Canal Injury by a Wooden Foreign Body. Case Rep Ophthalmol. 2018 Jul 6;9(2):341-347. doi: 10.1159/000490758.

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