The morphology of a smartphonopathic hand - smartphone use and the median nerve cross-sectional area

To investigate and compare the median nerve-cross sectional area at the wrist region of the dominant and non-dominant hands of high- and low- smartphone users.

This descriptive cross-sectional study was based on 128 human subjects conducted at Bahria University Health Sciences Karachi Campus from January to June 2022. The sample size was calculated using the method of sample size for frequency in a population www.openepi.com which is an open-source calculator, version 3-SSPropor using the following equation: Sample size n = [DEFF*Np(1-p)]/[(d²/Z²1-α/2*(N-1)+p*(1-P)]. The subjects were from MBBS, BDS, DPT, and Dental House Officers. They were grouped into two categories: high-smartphone users and low-smartphone users, based on the smartphone addiction scale (SAS). Ultrasound was carried out on each subject's wrist regions at the carpal tunnel level. The readings were compared between the dominant and non-dominant hands of each individual.

In this descriptive cross-sectional study on 128 subjects, the difference between the median nerve cross-sectional areas (MN-CSAs) of the dominant and non-dominant hand of the high-smartphone group was highly significant (p=0.007). The difference between the MN-CSAs of the dominant and non-dominant hand of the low-smartphone group was significant too (p=0.0103).

Smartphone overuse resulted in an enlarged median nerve, especially in the dominant hand.