Background: The facial nerve, a seventh cranial nerve, is typically assessed using electrodiagnostic tests such as nerve conduction studies, electromyography, and blink reflex. When diagnosing disorders affecting the muscles and peripheral nerves, neuromuscular ultrasonography is quickly becoming an integral part of the process. This study aimed to assess if facial nerve Ultrasonography (US) could be used for better evaluation of Bell's palsy.

Methods: This matched case control study was conducted on forty patients suffering from unilateral bell's palsy Detailed history. The facial muscle's function was assessed clinically every visit using the House-Brackman Classification of Facial function. All were subjected to evaluation by the electroneurography, blink reflex test, direct facial nerve conduction studies and Ultrasound imaging. The evaluation was done within the 14 days of the onset.

Results: As regard ultrasound cross-sectional area (CSA) among studied groups, there was highly statistically difference of facial nerve thickness between diseased and healthy group regarding proximal (p<0.001), midway (p<0.001), distal (p<0.001) sites. The facial CSA area at the proximal site could considered as a good discriminator of facial nerve palsy with area under curve (0.84) with 71% sensitivity and 83.9% specificity and a cutoff point 17 mm.

Conclusion: Establishing normal values of facial nerve nerves may be greatly aided by using ultrasound in conjunction with neural electrophysiology. In the early stages of Bell's palsy, ultrasonography could be useful for evaluating the condition's structural integrity and functional assessment.