Applied neurophysiology最新文献

Pain relief was evaluated in 40 patients with various types of deafferentation pain that were treated with dorsal root entry zone (DREZ) lesions produced with microsurgical lasers. Good long-term pain relief was evident in some paraplegics and in all patients with brachial plexus avulsion. Several other small subgroups of patients benefited from laser DREZ lesions as well. Pain associated with arachnoiditis and peripheral nerve injury or neuropathy did not respond to laser DREZ lesioning. Based upon the smaller lesion dimensions produced with the lasers, it is proposed that interruption of impulses in the tract of Lissauer may be a mechanism of pain control in patients that responded to laser DREZ lesions.

The current study was designed to measure and compare the size of dorsal root entry zone lesions made in the midthoracic spinal cord of anesthetized cats with a carbon dioxide laser and the radiofrequency (RF) probe utilizing currently employed clinical parameters. Cats were monitored intraoperatively with somatosensory evoked potentials (SSEPs) derived from stimulation of the ipsilateral posterior tibial nerve in order to assess the acute effect of lesion production on function within the ipsilateral dorsal column. Daily postoperative neurologic evaluations were recorded. The lesioned segments of spinal cord from sacrificed animals were examined histologically to determine the extent of cord injury at 1 and 30 days. SSEPs remained normal for the laser group, but were uniformly attenuated or lost in the RF group. Neurologically, the laser group fared better, with only a mild transient monoparesis, compared to a persistent moderate paraparesis for the RF group. On histologic examination, the depths of the laser and electrode lesions were similar, but the RF lesions showed more lateral spread. Laser lesions comprised 4.4 +/- 1.6% of the cross-sectional area of the spinal cord whereas the RF lesions occupied 22.8 +/- 4%. These findings demonstrate that at the parameters employed, the carbon dioxide laser produces smaller lesions than does the RF electrode.

Movement disorders may respond dramatically to properly placed lesions in thalamic and subthalamic areas. Proper location of lesions may be verified postoperatively by magnetic resonance imaging (MRI). Herein is reported a case of stereotactically placed bilateral lesions under computed tomography control using the Leksell apparatus, with successful clinical outcome, and the verification of lesion placement by subsequent MRI images.

Spinal and trigeminal dorsal root entry zone destruction (DREZ-tomy) was performed on 35 patients with deafferentation pain of various types. Overall, satisfactory pain relief was obtained in 65.5% of spinal DREZ-tomy cases in the follow-up observation. The result in the brachial plexus avulsion group was the best (82.4% improved), followed by the limb pain group without root avulsion (50.0%), but the truncal or visceral pain group showed the worst result (33.3%). Two patients with postherpetic trigeminal neuralgia were completely relieved of pain in the average follow-up period of 32 months, while in 2 patients with postrhizotomy facial pain, pain recurred 4 months after the operation in 1, and, in the other, pain in the medial part of the face remained unchanged. Complications were seen in about 60% of the patients, which were, however, all mild, except for 2 cases of death due to gastrointestinal disease.

Twenty-seven patients with intractable facial pain underwent dorsal root entry zone thermocoagulation lesion of the nucleus caudalis of the spinal trigeminal nucleus. Retrospective review revealed a success rate of 85% in the immediate postoperative period declining to 52% on subsequent follow-up. The best results were in the subgroup of patients with postherpetic neuralgia, of which 67% achieved definite relief. There tended to be some correlation of satisfactory results and pain quality as well as extent of pain along trigeminal territory. The operative morbidity was low although most patients were observed to have a mild transient ipsilateral dysmetria.

Age-dependent changes of short-latency somatosensory evoked potentials following median nerve stimulation in humans were investigated in two groups of healthy adults aged 20-30 and 50-60 years. Normative values for both age groups are given. Compared to the younger group, in the older one P27 latency and N20-P27 interpeak latency were about 2 ms longer, and P27-N35 and P27-P45 interpeak latencies were significantly decreased. These findings suggest that N20 and P27 are generated by different structures and that the subsequent components do not depend on P27.

The measurement of electrical impedance of normal and pathologic tissue has not been fully utilized in neurosurgery. This is a report of electrical impedance measurement in the central nervous system of both man and animals. We show the results of the laboratory study done in animals, in the brain and in the spinal cord as well. Also we show the clinical experience of the impedance recordings in the DREZ procedure for some chronic pain conditions, correlating the measurements at the time of the operation with normal conditions, with comments about the findings.