Tarsal tunnel syndrome (TTS) is a compression neuropathy that results from entrapment of the posterior tibial nerve or its branches. TTS may be treated either by conservative measures, including physical therapy, medications, and steroid injections, or by surgical decompression. Despite a variety of treatments, a few cases of TTS will relapse, and many cases of recurrent TTS will require re-operation. Pulsed radiofrequency (PRF) is known to have a number of advantages for pain management, particularly as this technique does not cause neural compromise such as motor weakness. Here, we report a new application of ultrasound-guided PRF in two cases of intractable TTS. Both patients had a long duration of severe foot pain and had been treated with various therapeutic modalities without lasting relief. We applied ultrasound-guided PRF to the affected posterior tibial nerve in each patient, and both had significantly reduced pain intensity scores and analgesic requirements without any complications. Ultrasound-guided PRF for intractable TTS relieved severe foot pain. It may supersede surgery as a reliable treatment for intractable TTS.

The mechanism of chronic pain is very complicated. Memory, pain, and opioid dependence appear to share common mechanism, including synaptic plasticity, and anatomical structures. A 48-yr-old woman with severe pain caused by bone metastasis of breast cancer received epidural block. After local anesthetics were injected, she had a seizure and then went into cardiac arrest. Following cardiopulmonary resuscitation, her cardiac rhythm returned to normal, but her memory had disappeared. Also, her excruciating pain and opioid dependence had disappeared. This complication, although uncommon, gives us a lot to think about a role of memory for chronic pain and opioid dependence.