Recently, botulinum toxin has been widely used for the management of spasticity. However it's mechanism of action in the skeletal muscle has not been well clarified. This study was performed to investigate the histopathologic changes in the skeletal muscle after botulinum toxin injection, and to determine the clinical standards of muscle fiber conduction study as an objective indicator for the changes of muscle fiber. As a study group, 35 Sprague Dawley rats were injected intra-muscularly with the botulinum toxin type A around two heads of right gastrocnemius muscle. After the injection of botulinum toxin, histopathologic studies and muscle fiber conduction studies were performed in 5 rats of the study group at 0, 1, 3, 5, 7, 14, and 28th day respectively. Based on the morphologic studies, the mechanisms of paralysis following the botulinum toxin injection were found to be both myogenic and neurogenic, and the motor function recovered through the formation of new motor end-plate and proliferation of Schwann cells. The muscle fiber conduction study revealed that the mean latencies of study group at 1, 3, 5, 7, and 14th day after the injection of botulinum toxin were significantly prolonged than those of the control group(p<0.05). The prolongation and slow recovery of latencies in a muscle fiber conduction study after the injection of botulinum toxin significantly reflect the morphologic changes of paralized skeletal muscles.
Animals ; Botulinum Toxins* ; Botulinum Toxins, Type A ; Head ; Motor Endplate ; Muscle Spasticity ; Muscle, Skeletal ; Paralysis ; Rats* ; Rats, Sprague-Dawley ; Schwann Cells

Central venous catheterization is a routinely performed procedure in clinical practice. While cerebral air embolism after the removal of the central venous catheter is very rare, it is one of the most serious complications that can lead to fatal outcomes. In this report, we present a rare case of a cerebral air embolism after the removal of the central venous catheter in a patient with a patent foramen ovale.

Accessory muscles located in the region of the popliteal fossa are very rare. MRI scan performed in a 52-year-old man with right knee pain revealed an anomalous muscle in the region of the popliteal fossa. Considering the muscle originated from the medial side of the lateral head of the gastrocnemius muscle and attached to the posteromedial articular capsule of the knee joint, it is consistent with the accessory popliteus muscle, previously reported. To our best knowledge, MRI finding about the accessory popliteus muscle has been reported in only one case. We present a case of the accessory popliteus muscle incidentally identified on MRI.

Lumbar paraspinal compartment syndrome is an uncommon cause of acute lower back pain. It can result from intense physical activity or as a complication of surgery or medication. Lumbar paraspinal compartment syndrome without external trauma is rarely reported in literature. We report a case of compartment syndrome that followed back muscle exercise and caused rhabdomyolysis. MRI findings include bilateral bulging of the paraspinal muscle, hyperintensity on T2-weighted image, and heterogeneous enhancement. Moreover, loss of intramuscular vasculature on a contrast-enhanced CT scan attributed to diagnose compartment syndrome in this case.