Pattern of muscle involvement according to needle electromyography findings in clinically unaffected extremities of polio survivors with lower extremity weaknesses

Aim: Late neuromuscular deterioration may be seen in patients with a history of paralytic poliomyelitis. One of these problems is the development of a new weakness in clinically unaffected muscles. We aimed to determine needle electromyography (EMG) findings in these clinically unaffected limb muscles and to contribute to the physiotherapy strategies of poliomyelitis. Methods: Patients with sequelae of poliomyelitis were included in this retrospective cohort study. Needle EMG findings of the patients were reviewed. If there were neurogenic needle EMG findings in the limb or muscle with no weakness, this muscle or limb was considered to be a subclinically affected muscle or limb. Results: Eighteen patients were included in the study. Needle EMG findings of 190 muscles were analyzed. In the lower extremities, 18 (72%) of 25 clinically unaffected muscles had neurogenic needle EMG findings, and 14 (35%) of 40 upper extremity muscles had subclinical involvement. In the lower extremity muscles, this subclinical involvement was significantly higher than in the upper extremity muscles (P=0.004). In clinically unaffected upper and lower extremity muscles, the most prominent neurogenic needle EMG findings were in the deltoideus and vastus lateralis muscles, respectively (P=0.022 and P=0.028, respectively). Conclusion: Subclinical involvement was more prominent in the lower extremity than in the upper extremity in polio survivors with weakness of lower extremity. The most prominent subclinical muscle involvement in the lower and upper extremities was the vastus lateralis and deltoideus muscles, respectively. We think that physical therapy strategies considering these findings will be beneficial for polio survivors.