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These results suggest that TrkA inhibitory peptide likely suppress melanoma-induced pain with concomitant reduction in the increased paw volume in a mouse skin cancer pain model.

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Nerve blocks using neurolytic agents (e.g., ethanol, phenol) in deep tissues have been performed under fluoroscopic or conventional computed tomography (CT) guidance. The recent development of C-arm fluoroscopic cone-beam CT, however, has made it possible to perform both real-time procedural evaluation (C-arm fluoroscopy) and three-dimensional (3D) image acquisition (cone-beam CT) in the same room without having to move the patient [1-3].We performed thoracic sympathectomy using ethanol in a 46-year-old female patient with complex regional pain syndrome in the right arm, after careful evaluation of the indications [4]. She suffered from spontaneous burning pain with a mean pain intensity of 7 on a numerical rating scale (PI-NRS; 0 = no pain, 10 = worst pain imaginable). With the patient in the prone position, we introduced two 10-cm, 21-gauge needles along the right lateral sides of the T2 and T3 vertebral bodies under fluoroscopic guidance (Fig. 1a, b) using DynaCT (Siemens Medical Solutions, Forchheim, Germany), and then injected 1 ml iopamidol, a radiopaque contrast medium, dissolved in 1 ml 2% lidocaine. Under technical support from a radiologic technologist, CT and 3D images were constructed. We verified proper needle positioning and proper spread of the medium during and just after injection ( Fig. 1c-h), and then confirmed that there were no signs of intercostal nerve block or Horner's syndrome. Finally, 1.5 ml ethanol was injected through each needle. The total duration of this procedure was 40 min, including 5 min for constructing CT and 3D images. The patient's PI-NRS decreased to 3 within 1 month after sympathectomy and has remained stable at 3 or 4 for at least 3 months. No adverse effects of the procedure were observed.Although a case of lumbar sympathectomy under C-arm fluoroscopic cone-beam CT has been reported [1], the usefulness of this technique for thoracic sympathectomy has not. Chemical thoracic sympathectomy can cause complications, including pneumothorax, intercostal neuritis, Horner's syndrome, and bradycardia [5], if the needles penetrate the pleura or the neurolytic agent spreads to the somatic roots or the lateral side of the T1, T4, or T5 vertebrae. C-arm fluoroscopic cone-beam CT provides information about both the spread of contrast media and the positional relationship between needles and bones before injection of the neurolytic agent, in addition to information from fluoroscopy alone. This technique could therefore be effective for preventing all these complications, except pneumothorax, as the needles might already penetrate the pleura before CT and 3D images are constructed.Although this technique needs 5-10 min for constructing CT and 3D images, in addition to the time required for nerve block under conventional fluoroscopic guidance, it could be useful in preventing the complications of nerve blocks, especially those using neurolytic injections in deep tissues, e.g., lumbar or thoracic sympathectomy, celiac

Chemical lumbar sympathectomy is performed to relieve pain from peripheral vascular disease. During sympathectomy under the conventional paravertebral method with X-ray fluoroscopic guidance, the neurolytic agent, injected at the L2-L4 level, can spread beyond the anterolateral plane of the vertebral body, where the lumbar sympathetic ganglion exists. This method, however, may cause genitofemoral neuralgia or lumbar plexus damage when the neurolytic agent spreads in or along the psoas muscle. 1,2 To prevent these complications when using conventional methods, the contrast media is injected first to confirm that the media does not spread into or along the psoas muscle. Although the striated pattern of contrast media in the front fluoroscopic view with X-ray fluoroscopic guidance is known to indicate the media spreading into or along the psoas muscle, the precise relationship between the media striated patterns and its anatomical distribution has not been fully analyzed.Recent progress in C-arm cone-beam CT made it possible to combine real-time X-ray fluoroscopic imaging with almost simultaneous CT image acquisition. The upper panel of Figure 1A shows the striated pattern of X-ray fluoroscopy during conventional chemical lumbar sympathectomy using C-arm cone-beam CT (DynaCT; Siemens Medical Solutions, Forchheim, Germany). The lower panel of Figure 1A, which is a lateral view of X-ray fluoroscopy, shows that the contrast media spread along the anterior edge of the L2 and L3 vertebral body. The transverse images of CT scan simultaneously demonstrate the spread of the media along the anterior surface of the psoas muscle ( Figure 1B).The lumbar plexus originates from the ventral rami of the L1-L4 nerve roots. The caudal branch of the L1 nerve unites with the anterior division of the L2 nerve to form the genitofemoral nerve. It then penetrates the psoas major muscle and generally bifurcates into the genital and femoral branches halfway along the anterior surface of the psoas muscle. Other branches from the L1-L4 roots, which mostly run within the psoas muscle at the L2-L4 level, form the obturator and the femoral nerves, 3 and are located in the posterior third of the psoas muscle. 4,5 By combining understanding from these recent anatomical investigations of the lumbar plexus with the evaluation of the images from conventional lumbar sympathectomy under C-arm cone-beam CT, we provide the precise information about anatomical distribution of striated pattern of the contrast media during conventional chemical lumbar sympathectomy with X-ray fluoroscopic guidance. Figure 1C,D show the sites of the genitofemoral nerve and the lumbar plexus in and along the psoas muscle. When the striated pattern of contrast media is observed in the front fluoroscopic view, the location of media in the lateral view provides additional useful information. The contrast media would reach to the genitofemoral nerve when it spreads around the anterior edge of the L2-L4 vertebral body in the lateral view. It would also reach to the lumbar plexus wh...