Working Diagnosis:
Paraviral optic neuropathy

Treatment:
Following optometry evaluation a MRI brain and orbits was obtained due to concern for optic neuritis. The patient received supportive care with hydration, nutrition, and rest, while undergoing an abbreviated return to play protocol. Symptoms were closely monitored when he was challenged with increasingly intense exercise.

Outcome:
On the first day after his MRI, the patient completed a noncontact practice without symptoms for 24 hours afterwards. On the second day, he completed a contact practice with no symptom. The patient's vision gradually returned to normal over the next couple days at which time he was cleared for full participation. Following clearance, he was able to participate in a collegiate conference football game three days later without complication.

Author's Comments:
Multiple conditions, such as dehydration and viral illness, can cloud clinical presentations altering the ability to accurately diagnose or exclude concussion in contact sports. Sport related concussion certainly must be considered in all headache events in contact sport athletes, but equal consideration should be given to alternative diagnosis of post-traumatic headache(1). This patient's course illustrates how a preceding viral illness led to dehydration and local optic nerve pathology which created the clinical appearance of a possible concussive event despite sideline neurological and concussion tests being unremarkable. To prevent unnecessary restriction from sports and treat other conditions properly, it is important to consider concussion-mimicking conditions in addition to concussion.

Viral optic neuropathies are reported to a limited extent in medical literature. Most case reports indicate paraviral optic neuropathies present with unilateral or bilateral vision loss one to three weeks following a respiratory or gastrointestinal infection with influenza, Epstein-Barr virus, chicken pox, measles, or mumps (2,3). Direct viral infection of the optic nerve or immune-mediated inflammatory processes are thought to be the underlying etiology (2). Papillitis with retinitis is commonly found on ophthalmologic exam, and subtle signs of viral meningoencephalitis may be seen on MRI or cerebrospinal fluid analysis (2,3). Normal MRI findings generally indicate a more favorable prognosis (2,4). Outcomes are generally excellent with self-limited symptoms and full return of vision without treatment, although treatment with corticosteroids is favored in cases of bilateral or severe vision loss (2,3). Presentations may be more severe in children, as encephalitic optic neuropathies may present with seizures or cerebellar dysfunction. Case-series studies reported all these children returned to a healthy baseline with intravenous corticosteroids followed by a two-month tapered oral corticosteroid course (5). Another serious condition with a similar presentation is optic neuritis. As studied in the Optic Neuritis Treatment Trial, optic neuritis often forebodes negative future outcomes (e.g., a presenting sign of multiple sclerosis, relative afferent pupillary defects, persistent visual loss, optic atrophy, color desaturation) (4). However, this patient's vision recovery and normal MRI indicated a likely favorable outcome. In the event of symptom relapse in the future, further workup of autoimmune conditions would be indicated (2,3).

Editor's Comments:
In addition to infectious etiologies, there are many other causes of optic neuropathies. Ischemic causes are more common in older patients. As mentioned, optic neuritis, which is often associated with multiple sclerosis, is another important cause to consider. It is usually associated with optic nerve inflammation on MRI. Optic neuritis is also less commonly associated with autoimmune and systemic inflammatory conditions such as sarcoidosis or lupus. Compression from a tumor, abscess, or other mass can cause optic neuropathy as well as certain drugs or radiation therapy. It is also associated with vitamin B1, B12, and folate deficiencies, which are exacerbated by tobacco and alcohol use. Finally, there are genetic causes, which typically present in children.

References:
1. Harmon KG, Clugston JR, Dec K, et al. American Medical Society for Sports Medicine position statement on concussion in sport. British Journal of Sports Medicine 2019;53:213-225.
2. Osborne B, Balcer L, Optic neuropathies. UpToDate. Sept 2019.
3. Kaloun R, Abroug N, Ksiaa I, et al. Infectious optic neuropathies: a clinical update. Eye Brain. 2015;7:59-81.
4. Osborne B, Balcer L. Optic neuritis: Pathophysiology, clinical features, and diagnosis. UpToDate. Sept 2019.
5. Farris BK, Pickard DJ. Bilateral postinfectious optic neuritis and intravenous steroid therapy in children. Opthalmology. 1990 Mar;97(3):339-345.

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