Paraplegia and sensory disturbance are the symptoms often recognized in case of spinal cord lesion including trauma, tumor, demyelinating diseases and spinal cord infarction. In pain clinic area, neurological symptom of paraplegia may occur as an unexpected complication of the nerve block with neurolytics and it is important that we should understand pathological and anatomical basis of the spinal cord lesion. We experienced a case presenting a symptom of the paraplegia which was unexplainable for anterior spinal artery syndrome after the intercostal nerve block with neurolytics. The patient was 72 years old male with post herpetic neuralgia at the second thoracic nerve. The second intercostal nerve was blocked using 2.5 ml of 7% phenol water. Paraplegia and partial sensory disturbance below the 10th thoracic nerve were recognized after the block.
   We speculated the following mechanism of this complication. Phenol water partially entered into intercostal artery accompanying an intercostal nerve and drug solution spread against arterial blood flow because of the injection pressure was higher than arterial blood pressure. The drug solution entered into the intercostal artery spread to the spinal branch and the spinal cord supplied with this artery was partially damaged.
   There is a clear somatotopic organization of the fibers and an overlap of collaterals of ascending and descending branches of the dorsal root in the spinothalamic tract. There is also a segmental organization of the fibers in the spinothalamic tract and corticospinal tract. These tracts contain both transverse crossing fibers and uncrossing fibers. Nathan reported that the fibers subserving different sensory modalities did not 1 form the same angle with the long axis of the cord as they cross the cord. The difference in the angle of slope would lead to a different level of sensory loss for different modalities.
   It is considered that the sensory disturbance observed after the second intercostal nerve block appeared at the level of the 10th thoracic spinal cord level.It is important to be familiar with the anatomy of the spinal cord when performing neurolytic nerve blocks.

抄録全体を表示

   Substance P (SP) is the most popular neuropeptide currently considered in detail, and has been widely studied as an excitatory factor of nociception. However, analgesic effects were not clearly shown by inactivation of SP receptors by the use of SP receptor antagonists or SP knock-out mice in some recent studies. In order to investigate the mechanism, we studied the excitatory and inhibitory effects of SP and SP receptor agonists on deep dorsal horn (DH) neurons of the spinal slice preparation by using patch clamp method. We used neurokinin 1 (NK1) receptor agonist ([Sar⁹, Met(O₂)¹¹]SP: 1.0 µM), because SP has highest affinity for NK1 receptor in three SP receptors (NK1, NK2, and NK3). Bath application of SP or NK1 receptor agonist for 1 minute increased the frequency of spontaneous excitatory postsynaptic currents (sEPSC) mediated by glutamate in deep DH. SP and NK1 receptor agonist induced enhancement of glutamate release from interneurons and/or primary afferent fibers onto deep DH neurons. On the other hand, the application of SP or NK1 receptor agonist largely increased the frequency of spontaneous inhibitory postsynaptic currents (sIPSC) and miniature inhibitory post synaptic currents (mIPSC) mediated by GABA and/or glycine in deep DH. These findings suggested that SP and NK1 receptors are expressed in GABAergic and/or glycinergic interneurons and that their activations facilitated GABA and/or glycine release onto deep DH neurons. In summary, it has been thought SP is generally participating in the enhancement of excitatory nociceptive pathway, but these results made clear that SP induced enhancement of inhibitory nociceptive transmission in deep DH. Clinical treatment of SP receptor antagonists against pain has been proposed for a long time, but is not established yet. Our observation in this study revealed it is necessary to consider the inhibitory effects of SP in the spinal deep dorsal horn in clinical application of SP receptor antagonists for the treatment of various pain sensation.

抄録全体を表示

   Peripheral nerve blocks with 1% dibucaine were performed on 30 trigeminal nerve branches in 13 patients suffering from idiopathic trigeminal neuralgia not responsive to topical anesthetics at conventional concentrations. While the pain was alleviated in 20% of the branches for more than 6 months, the effect lasted less than 1 month in 43.3% of the branches, with an average effective duration of 6.8 months. While the duration of the effective periods varied, this method was relatively free from the sensory disturbances typically associated with blocks using neurolytic agents. Peripheral nerve blocks with 1% dibucaine therefore may be considered a viable alternative in situations where block treatments with topical anesthetics at ordinary concentration are ineffective.

抄録全体を表示