Complete and incomplete lower motor neuron facial palsy in post-COVID-19 mucormycosis.

Purpose: To study facial nerve palsy (FNP) in post-COVID-19-mucormycosis patients and its ocular complications, report different presentations of FNP in such patients, and propose its etiopathogenesis based on presentation and clinico-radiologic localization.

Methods: A prospective cohort study was carried out in patients of post-COVID-19-mucormycosis who presented at our tertiary center, over a period of 3 months. Motor and sensory examination of the facial nerve was done to diagnose FNP and localize the lesion clinically. Slit-lamp examination was done for grading corneal involvement. MRI brain, orbit, and paranasal sinuses (PNS) with contrast were studied to find involvement along the facial nerve. It was assessed whether this site of lesion corresponded with clinical localization. Data were analyzed using the percentage of total cases and Fisher's test.

Results: A total of 300 patients with post-COVID-19 mucormycosis were examined, of which 30 (10%) patients were found to have FNP. All were lower motor neuron (LMN) type and were associated with corneal complications. The most common site clinically was distal to the chorda tympani (66.66%) and radiologically was infratemporal (IT) fossa (63.4%). The clinical localization significantly correlated with the radiological findings (P = 0.012). Twenty percent of patients showed incomplete involvement of facial muscles.

Conclusion: FNP was found to be of LMN type. The most common site of insult was IT fossa. There was a good clinico-radiological correspondence of lesions. Isolated lesions were also found along the peripheral nerve course, presenting as incomplete facial palsy. Recognition of FNP in post-COVID-19 mucormycosis, in all its variable forms, is important to manage corneal complications.