Treatment of acquired partial oculomotor nerve palsy with dexamethasone – A case report

INTRODUCTION/IMPORTANCE: Oculomotor nerve palsy is an acquired condition caused by injury to the third cranial nerve. Patients present classically with their eye in a "down and out" positioning, ptosis and abnormalities in most extraocular movements causing diplopia. Ocular dysfunction may be due to a variety of different etiologies, such as aneurysm, microvascular disease, trauma, and viral infections. Clinical prognosis is usually quite good and is often self-limiting. CASE REPRESENTATION: We present a case of an otherwise healthy 40-year-old male who awoke one morning with moderate diplopia, unable to focus with binocular vision and developed eyelid ptosis two days later. He was previously infected with the Omicron variant of COVID-19; however, a rapid test could not confirm it. No intracranial or vascular pathology were identified on CT head, CT angiogram, or MRI. Repeat COVID-19 PCR test was negative. He was assessed by a neuro-ophthalmologist and was diagnosed with left partial oculomotor nerve palsy presumed secondary to viral microvascular injury. COVID-19 infection seemed likely given the history but could not be confirmed. The specialist recommended monitoring the patient without any treatment, with no recommendation of corticosteroid use. CLINICAL DISCUSSION: Cranial neuropathy guidelines for viral palsies involving the 7th or 8th cranial nerve are treated with corticosteroids. After considering the risks, the patient elected treatment with a left eye patch and a dexamethasone taper. Full return of function in all extremes of gaze was restored less than 2 months after onset. CONCLUSION: Given the complete and timely recovery, it may be reasonable to consider corticosteroids for all cranial neuropathies.