Abstracts
(372) Discovery of a novel type of local anesthetic agent J Petruska and K Rau; University of Louisville, Louisville, KY We have identified a novel local anesthetic effect of an existing FDA-approved drug. Structurally, the agent is unique compared to other drugs directed toward its intended-target and compared to ‘caine-family local-anesthetics. Preliminary computational analysis of structure indicates that there is a strong opportunity for development of novel derivative structures. In addition to providing a unique structure, the agent also provides unique characteristics in addition to those expected of a clinically-useful local anesthetic: CThe local anesthetic effect appears due to mechanisms distinct from those associated with the major known effect for which the agent was designed and has been used (i.e., local anesthesia represents a novel-use). CThe agent provides rapid and reversible block of conduction of both large and small peripheral nerve sensory axons. CThe agent provides partial sparing of peripheral nerve motor axon conduction, a unique and potentially advantageous feature for many applications. C The local anesthetic effect is not due to induction of hyperpolarizing currents. C The agent is an effective local anesthetic in both na€ ıve condition and in a model of sensory neuron pathology. This poster is meant to encourage and facilitate interactions to foster the development of this agent and potential derivatives as novel clinically-directed local anesthetic agents.
(373) Ultrasound-guided genicular nerve block for persistent knee pain after knee surgery Z Gong and E Ottestad; Stanford Pain Management Center, Redwood City, CA A 45 year old male with chronic left knee pain initially due to patellar tendonitis underwent two arthroscopic knee surgeries. The second surgery relieved his original left knee pain. However, afterwards he developed a different pain in the same knee which located more anterolateral and was sharper than his previous achy pain. Multiple intraarticular knee injections and a saphenous nerve block did not alleviate the pain during local anesthetic phase. A popliteal fossa sciatic nerve block did provide temporary 100% analgesia but pulsed radiofrequency (pRF) modulation of the sciatic nerve brought no durable benefit. The articular branches of the knee joint are known as the genicular nerves which consist of the superior lateral (SL), superior medial (SM), inferior lateral (IL), inferior medial (IM), and recurrent tibial genicular nerve. Radiofrequency neurotomy of genicular nerves targeting SL, SM, and IM branches was first reported to lead to significant pain reduction and functional improvement in a subset of elderly with chronic osteoarthritic knee pain.1 Instead of fluoroscopy, we decided to perform a diagnostic left knee genicular nerve block under ultrasound guidance for more accurate localization of each genicular nerve (near corresponding genicular arteries). The arteries and nerves were well visualized and the initial SL genicular nerve block gave him 50% pain improvement and addition of IM and SM genicular branch blocks provided another 15-20% pain relief. We then proceeded with ultrasound-guided pRF modulation and block of the SM and SL genicular branches which resulted in 70% pain relief. The IM branch was not included during the pRF because of his full functional recovery after the first two nerves were blocked. Depending on his response to the pRF neuromodulation, we may move forward with thermal RF ablation if needed. (1. Choi, Pain, 2011.)
The Journal of Pain
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(374) Single shot ultrasound guided thoracic paravertebral space (TPVS) block as primary anesthetic for video assisted thoracoscopic surgery (VATS) C Dadachanji and Y Khelemsky; Mount Sinai Medical Center, New York City, NY To describe the application of a single shot ultrasound-guided thoracic paravertebral block as the primary anesthetic for video assisted thoracoscopic surgery. Case Report: An 87 year old female presented for video assisted thoracoscopy with drainage of pleural effusion and talk pleurodesis. Due to her poor functional status, as well as patient’s and family’s wishes to avoid endotracheal intubation, the procedure was performed successfully after a single shot ultrasound guided thoracic paravertebral block and sedation. A single shot ultrasound guided thoracic paravertebral block may be utilized as a primary anesthetic for video assisted thoracoscopy.
F08 Neural Stimulation: Non-Interventional (TENS, Transcranial) (375) Incorporating high frequency repetitive transcranial magnetic stimulation as a routine therapy for migraine headache: a case series L Shi, A Fallah, and A Leung; VA San Diego Healthcare System; UC San Diego Health System - La Jolla, La Jolla, CA Transcranial magnetic stimulation (TMS) has been developed as a non-invasive therapeutic modality to treat migraine headache. Single-pulse TMS (sTMS) is established as an effective abortive therapy for migraine with aura. Repetitive TMS (rTMS) can work as prophylactic therapy in the management of chronic migraine. This case series investigates the clinical feasibility of utilizing repeated sessions of rTMS as prophylactic and maintenance therapy in patients with refractory migraine headache. A total of 7 patients (age range 31-64 years) meeting the international criteria of migraine with aura (4 patients) or without aura (3 patients) were included. All patients suffered from debilitating daily headache refractory to multiple preventive and abortive medications. All patient received 3 sessions (2-week interval between each session) of high frequency (10 Hz) rTMS (3000 pulses per session) to the left dorsolateral prefrontal cortex and left motor cortex. To evaluate immediate effect, pre- and post-treatment spontaneous pain levels were assessed with a numerical pain scale (NPS). To assess the long-term effect, the frequency, severity and duration of migraine attacks before and after 3 sessions of rTMS treatment was compared for each patient. An immediate pain relief following each rTMS session was seen in all 4 patients with migraine with aura, corroborating previous findings. Follow-up clinic visits of all 7 patients from both groups revealed significant long-term benefit of this rTMS regimen over migraine attacks. Specifically, 50-75% reduction in frequency, 50-90% reduction in duration and 40-75% reduction in NPS was reported. This case series indicates 3 sessions of rTMS separated by 2 weeks is a promising treatment for patients with intractable chronic daily migraine headache (with or without aura). We are currently investigating if a maintenance regimen of rTMS (once every 4 weeks) following the initial 3 bi-weekly treatment sessions can exert long-lasting benefit on migraine patients.