THE RELATIONSHIP BETWEEN SOMATOSENSORY EVOKED POTENTIALS AND INTRAOPERATIVE SPINAL CORD EVOKED POTENTIALS.
Taku Ogura, Hitoshi Hase, Tatsuro Hayashida, Toru Osawa and Yasusuke Hirasawa.
(Department of Orthopedic Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan)
There are still problems in applying cervical somatosensory evoked potentials ( SEPs ). In this study, we evaluated the correlation of abnormal SEPs with clinical variables in patients.
We studied cervical SEPs evoked by stimulation of median, ulnar nerves in 16 normal subjects and 40 patients with clinical findings and MRI evidence of cervical myelopathy. Cervical SEPs of 10 patients are compared with evoked potentials during cervical surgery. The recording electrodes were placed in the supraclavicular fossa (Erb's point ), referred to Erb's point contralateral to the stimulated side, over the spinous process of the CV5 vertebrae, referred to the anterior neck, and at scalp locations (C3', C4'), referred to the lateral neck contralateral to the stimulated side. For clinical evaluation, we used the rating score (clinical score) as developed by Japanese Orthopaedic Association. To evaluate abnormalities of the spinal N13 potential, we used a grade classification consisting of 5 grades.
There was significant correlation between our grade classification of spinal N13 and clinical variables in patients (p<0.01), whereas there is no significant differences in peak latencies or N9-N13 interpeak latencies on spinal N13 and clinical score. By adding N9-P14 interpeak intervals, conductive latencies, cervical SEPs in patients may be useful clinically to estimate cervical cord dysfunction. This result was supported by evoked potentials during surgery.
LUMBAR MOTION PATTERNS RELATED TO CHANGES IN NERVE ROOT IRRITATION
Teuvo Sihvonen, MD, PhD., Veli Tumnen, MD(#), Matti Luukkonen, MD(&), Olavi Airaksinen, MD, PhD.
Department of Physical and Rehabilitation Medicine, Department of Surgery(#) and Department of Neurosurgery(&), University Hospital of Kuopio, SF-70210 Kuopio, Finland
Purpose: The absence of flexion relaxation (FR) of paraspinal muscles during lumbar-pelvic rhythm in low back pain (LBP) patients has been shown to be the most common difference in dynamic back muscle activity when compared to painfree persons. The aim of this study was to compare back muscle function in acute back pain caused by disc herniation and changes in it along treatment and healing.
Methods: In 11 LBP patients (29-43 yrs) with sciatica disc herniation was confirmed with CT or MRI at L4 or L5 lumbar level. Lumbar-pelvic rhythm during sagittal flexion and extension was registered with surface EMG and two-inclinometer method by using back function analyzer. The Analyzer measures simultaneously the interaction between spinal and pelvic movements and back muscle activity.
Results: Compared to normal activity pattern, after disc herniation in kinetic EMG FR of the back muscles was lacking and EMG activity phases during extension and flexion were fused together and could not be separated from each other. After conservative interventions in all patients back pain and radiating symptoms disappeared and the pattern of lumbar function normalized: EMG activity phases in back flexion and extension could be separated clearly and normal RF was present.
Conclusions: 1) Current LBP affects to lumbar motion patterns giving valuable and qualitative information when evaluating tissue irritation and patients' functional disturbances. 2) It is possible to use this as new diagnostic test to objectify motor and coordinative changes related to nociceptive structural and functional reasons, and 3) confirm intervention effects in back pain alleviation.