A Puzzling Pair: Flail Leg Syndrome with Myokymia and Avascular Hip Necrosis-Case Study and Systematic Literature Review.

Background: Radiation-induced lower motor neuron syndrome (LMNS) represents a rare but significant delayed complication of oncologic treatment. Methods: We present the case of a 56-year-old female who developed LMNS, myokymia, and osteoradionecrosis of the hip nearly two decades after receiving pelvic radiation therapy for cervical carcinoma. To the best of our knowledge, no previous reports have described this particular triad of neurological and tissue changes following radiation therapy. This clinical presentation is analyzed within the framework of a systematic review encompassing 58 documented cases, including our own. Results: The database searches yielded 530 records. In total, 32 studies were included in the qualitative synthesis, reporting 57 unique cases of post-radiation LMNS. With the addition of our present case, the final analysis comprised 58 cases. The majority of analyzed patients were male (77.2%), and the most frequent primary malignancies were germ cell tumors (57.9%). The mean age of the analyzed patients at symptom onset was 40.5 ± 13 years, with radiotherapy administered at a mean age of 30.3 ± 12.5 years. The latency period between radiation exposure and the emergence of neurological symptoms averaged 10.2 ± 8.7 years. The mean cumulative radiation dose was 49.0 ± 14.0 Gy. Myokymic discharges were identified in 6 patients (10.3% of cases). Comparative analysis revealed no significant clinical or radiological differences across malignancy subtypes in the manifestation of post-radiation LMNS. Conclusions: These findings highlight the need for long-term surveillance of irradiated patients.