Periodic leg movements during either epidural or spinal anesthesia in an elderly man without sleep-related (nocturnal) myoclonus.

We report a case of periodic leg movements (PLM) observed in an 86-year-old man during either midthoracic epidural anesthesia or spinal anesthesia. The PLM observed were stereotyped (extension of the big toe in combination with partial flexion of the ankle, knee, and hip lasting 3-5 s) and repetitive (interevent intervals between jerks were 20-40 s) for about 120 and 30 min respectively. The patient was awake but unaware of the PLM unless reminded. The present case was quite similar to sleep-related (noctural) myoclonus (SRM) in every respect except for its occurrence during wakefulness. SRM is more prevalent in the elderly population but its mechanism remains to be elucidated. Previously, we had reported a case of PLM observed in an elderly man with SRM. In our two cases, PLM were seen only while the local anesthetic was acting on the spinal cord; therefore, these anesthesia-related PLM (ARPLM) may suggest that the spinal cord is involved. In particular, we consider that physiological changes seen commonly during non-rapid-eye-movement sleep and a certain phase of anesthesia, such as suppression of the descending inhibitory pathway, and pyramidal tract dysfunction are relevant to ARPLM. In addition, the concomitant alteration of the blood flow in the leg and changes due to aging of the spinal cord may also be involved.