Potential sex differences in activation of pain-related brain regions in nonhuman primates with a unilateral spinal nerve ligation

The lack of truly robust analgesics for chronic pain is owed,in part,to the lack of an animal model that reflects the clinical pain state and of a mechanismbased,objective neurological indicator of pain.The present study examined stimulus-evo ked brain activation with functional magnetic resonance imaging in male and female cynomolgus macaques following unilateral L7 spinal nerve ligation and the effects of clinical analgesics pregabalin,duloxetine,and morphine on brain activation in these macaques.A modified straight leg raise test was used to assess pain severity in awake animals and to evo ke regional brain activation in anesthetized animals.The potential effects of clinical analgesics on both awake pain behavior and regional brain activation were examined.Following spinal nerve ligation,both male and female macaques showed significantly decreased ipsilateral straight leg raise thresholds,suggesting the presence of radicula rlike pain.Morphine treatment increased straight leg raise thresholds in both males and females whereas duloxetine and pregabalin did not.In male macaques,the ipsilateral straight leg raise activated contralateral insular and somatosensory cortex(Ins/SII),and thalamus.In female macaques,the ipsilateral leg raise activated cingulate cortex and contralateral insular and somatosensory cortex.Straight leg raises of the contralateral,unligated leg did not evoke brain activation.Morphine reduced activation in all brain regions in both male and female macaques.In males,neither pregabalin nor duloxetine decreased brain activation compared with vehicle treatment.In females,however,pregabalin and duloxetine decreased the activation of cingulate cortex compared with vehicle treatment.The current findings suggest a diffe rential activation of brain areas depending on sex following a peripheral nerve injury.Diffe rential brain activation observed in this study could underlie qualitative sexual dimorphism in clinical chronic pain perception and responses to analgesics.Future pain management approaches for neuropathic pain will need to consider potential sex differences in pain mechanism and treatment efficacy.

Arthroscopic approach to the posterior compartment of the knee using a posterior transseptal portal

Arthroscopic surgery of the posterior compartment ofthe knee is difficult when only two anterior portals are used for access because of the inaccessibility of the back of the knee. Since its introduction, the posterior transseptal portal has been widely employed to access lesions in the posterior compartment. However, special care should be taken to avoid neurovascular injuries around the posteromedial, posterolateral, and transseptal portals. Most importantly, popliteal vessel injury should be avoided when creating and using the transseptal portal during surgery. Purpose of the present study is to describe how to avoid the neurovascular injuries during establishing the posterior three portals and to introduce our safer technique to create the transseptal portal. To date, we have performed arthroscopic surgeries via the transseptal portal in the posterior compartments of 161 knees and have not encountered nerve or vascular injury. In our procedure, the posterior septum is perforated with a 1.5-3.0-mm Kirschner wire that is protected by a sheath inserted from the posterolateral portal and monitored from the posteromedial portal to avoid popliteal vessel injury.

Isolated Metastatic Barrett’s Adenocarcinoma of the Thoracic Epidural Space Causing Paraplegia

Barrett’s adenocarcinoma is an esophageal cancer arising from Barrett’s esophagus. In this report, a metastatic epidural tumor from Barrett’s adenocarcinoma with paraplegia that required surgical treatment is documented. A 50-year-old man who had had a resection of the distal esophagus due to Barrett’s adenocarcinoma six month before presented with progressive weakness and numbness in lower limbs with urinary disturbance. Magnetic resonance imaging of the thoracic region revealed compression of the spinal cord at the T3-4 level by a dorsally located epidural mass. No signal changes were detected in vertebrae. Since the paraplegia and urinary disturbance were rapidly progressing, laminectomy and tumor resection was performed. Postoperatively, neurological function improved immediately and there was no recurrence of spinal region. This is the first report on an isolated metastatic Barrett’s adenocarcinoma of the thoracic epidural space.

Arthroscopic Classification of Suprapatellar Plica and Medial Synovial Plica

In the previous arthroscopic studies, the ratio of presence and type of plica was somewhat different. We arthroscopically investigated and classified suprapatellar plica and medial synovial plica in a Japanese population. Subjects and Methods: The anatomy of suprapatellar plica and medial synovial plica was studied arthroscopically in 130 knees. Original diagnosis of patients included in this study were 53 meniscal injuries, 51 ACL injuries, 17 osteoarthritis, 5 popliteal cysts, 3 osteochondritis dissecans, and 1 synovial osteochodromatosis. Results: The suprapatellar plica was present 73.8% and classified into 6 types which were arch type, medial type, lateral type, perforated type, pillar type and complete type. The medial synovial plica was present 62.3% and classified into 4 types which were narrow type, medium type, broad type and perforated type. No relationship between age and the pattern of the suprapatellar plica or medial synovial plica could be found. There was no trend to be correlation between the type of suprapatellar plica and medial synovial plica. Conclusion: We classified suprapatellar plica by only location and shape of plica and medial synovial plica by the size of plica.