16 - Involvement of Median Nerve Anatomical Variations and Surgical Implications Among Population

Poster Board Number: 16
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Abstract Body : Variations in the median nerve, such as the origin and distribution, have been well documented. Due to significant differences in the reported prevalence of such anatomical variations, we aimed to provide a detailed comprehension of the median nerve using demographic variables such as ethnicity and sex to evaluate occurrence and incidence between populations. A wide-ranging knowledge of the median nerve variations can contribute for interpretation of clinical manifestations, such as compression syndromes, nerve displacements, and sensory deficits. As the median nerve travels down the upper extremity, it passes through the flexor retinaculum, in which certain distal variations will cause carpal tunnel syndrome due to increased intraductal pressure. A systematic search of all major databases was performed from 2017 – 2022 to identify studies on the prevalence of median nerve variations. Twenty studies (n = 445 arms; 94 females, 139 males) from Caucasian, Indian, Malaysian, Russian, French, and Iranian ethnicities were included in the systematic analysis. The pooled prevalence rates of the variations in the forearm and thenar muscles courses were approximately 42.6%. The variations of the median nerve courses at the wrist 58% were more commonly found compared to at the site of the brachial plexus and forearm 42%. The median nerve presented a significant number of variations in its thenar branch course, classified into Poisel and Lanz classifications of the evaluated studies. Awareness of anatomical variations regarding hand innervation is essential, particularly when considering physical examination, prognosis, diagnosis, and surgical treatment to explain paradoxical motor and sensory loss in patients.