LESIONS

A Guide to Localisation in Neurology

Painful visual loss

Outcome

The patient was seen the same day by an ophthalmologist who confirmed this was severe optic neuritis.

He was treated with high-dose intravenous and then oral steroids. An MRI showed changes in the posterior part of the left optic nerve.

His visual acuity had not changed after the intravenous steroid treatment, and there was concern for an aggressive neuroinflammatory disorder, so he was treated with plasma exchange while awaiting antibody results. However, an extensive workup for causes of optic neuritis was negative, including aquaporin-4 (AQP4) and myelin-associated glycoprotein (MOG) antibodies. He also had negative genetic testing for hereditary optic neuropathies.

Unfortunately the patient’s visual impairment did not improve. The right eye remained intact. He had no further neurological episodes.

He remains under follow-up. One consideration being debated is whether to provide long-term immunosuppression incase this is seronegative neuromyelitis optica (NMO)- a condition that can only be formally diagnosed after a second attack, which could be devatstating. Treating could potentially prevent this, but is not without risk. Such uncertainty is a major part of real-world neurology.

Severe optic neuritis with no recovery after steroid and plasma exchange therapies, with no cause found, but concern for seronegative neuromyelitis optica.

1. Acute monocular visual loss has many causes, most of which are not 'neurological' - important bedside tests include inspection for redness, pupil size, reactivity and ophthalmoscopy
2. Optic nerve pathology causes loss of central vision with reduced colour vision, typically red-green desaturation, and a relative afferent pupillary defect
3. Atypical optic neuritis is suggested by severe visual loss (light-dark perception only), bilateral involvement, painlessness, progression over several weeks, and lack of recovery
4. Evidence supports IV steroid treatment in severe cases to accelerate recovery, and if atypical disease is suspected, plasma exchange is often used.

Bennett et al (2023).Optic neuritis and autoimmune optic neuropathies: advances in diagnosis and treatment. Lancet Neurology