neurologic disorders
Treatment of Pain
Neural Blockade
Interrupting nerve transmission in peripheral or central pain pathways via drugs or physical methods provides short-term and sometimes long-term relief. Neuroablation (pathway destruction) is used rarely; it is typically reserved for patients with an advanced disorder and a short life expectancy. Local anesthetic drugs (eg,lidocaine) can be given IV, intrathecally, intrapleurally, transdermally, subcutaneously, or epidurally. Epidural analgesia using local anesthetics or opioids is particularly useful for some types of postoperative pain. Long-term epidural drug administration is occasionally used for patients with localized pain and a short life expectancy. Generally, for long-term neuraxial infusion, an intrathecal route via an implanted pump is preferred. Neuroablation involves interrupting a nociceptive pathway surgically or using radiofrequency or microwave energy, cryoablation, or caustic substances (eg,phenolor high-concentration alcohol) to produce a lesion. Neuroablation is more effective for somatic pain than for visceral pain. The most common neuroablation procedures are used to treat mechanical axial spine pain: these procedures involve radiofrequency ablation of the medial branches of the dorsal spinal root rami (which innervate zygapophyseal [facet] joints) or ablation of the lateral branches (which innervate the sacroiliac joint). This technology is also being increasingly used to treat refractory pain in the knee (genicular nerve), hip ([articular sensory] branches of the obturator and femoral nerves), and shoulder ([articular sensory] branches of the suprascapular, axillary and lateral pectoral nerves). Neuroablation in the spinal cord has been rarely used; it is difficult to predict its effectiveness. Neuroablation of the ascending spinothalamic tract (cordotomy) can be used to disrupt pain from an area of the body (eg. whole limb); it may provide relief for several years, although numbness and dysesthesias develop. Neuroablation of the dorsal roots (rhizotomy) is used when a specific dermatome can be identified. 