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Biomedical subjects

R Leppanen

Publications and source records attributed to R Leppanen.

4 recordsLinked to original sources
PubMed1995

Intraoperative lower extremity reflex muscle activity as an adjunct to conventional somatosensory-evoked potentials and descending neurogenic monitoring in idiopathic scoliosis.

STUDY DESIGN: Lower extremity polysynaptic reflexes and descending neurogenic motor and ascending somatosensory activity were recorded. OBJECTIVE: Two cases are presented to illustrate the intraoperative use of lower extremity reflex recordings for detecting compromise of spinal cord function. SUMMARY OF BACKGROUND DATA: Lower extremity reflex processing can be used to measure integrated spinal cord activity, whereas descending neurogenic and ascending somatosensory potentials measure only long tract function. METHODS: Eight channels of lower extremity polysynaptic reflex activity were recorded simultaneously after unilateral lower extremity mixed nerve stimulation. Sequential descending neurogenic and ascending somatosensory activity was recorded simultaneously with reflex recordings. RESULTS: In these two patients with idiopathic scoliosis, intraoperative reflexes changed before descending neurogenic and before ascending somatosensory activity changed. High-amplitude synchronous persistent reflex activity correlated with a postoperative neurologic deficit. Low-amplitude asynchronous transient reflex activity was not associated with a postoperative neurologic deficit. CONCLUSION: Intraoperative lower extremity reflex changes are more sensitive to spinal cord compromise than are changes in long tract function. Lower extremity polysynaptic reflexes monitor the integrated activity of the spinal cord that is responsible for the control of complex motor behavior.

Adolescent↗
PubMed1995

Evaluation of intrapedicular screw position using intraoperative evoked electromyography.

STUDY DESIGN: This study analyzed the parameters needed for electrical stimulation of vertebral pedicle drill bits and screws. OBJECTIVES: The feasibility of using electrically evoked electromyography was studied. SUMMARY OF BACKGROUND DATA: Considerable potential for damage of adjacent nerve roots with incorrectly placed bits and screws exists with pedicular fixation of the lumbar spine. METHODS: Ninety-five drill bits, one hundred forty-four screws, and thirty-four exposed nerve roots were electrically stimulated in thirty-six patients. Simultaneous evoked electromyographic activity was recorded from four muscle groups in each lower extremity during partial neuromuscular blockade. RESULTS: A constant current threshold of 6 mA or less correlated with misplaced drill bits and screws that broached the cortex. Evoked electromyography was 93% sensitive whereas radiography was only 63% sensitive to detecting bits and screws that had broached the cortex. CONCLUSIONS: Evoked electromyography is a valuable sensitive adjunct to radiographic examination of pedicle drill bit and screw placement.

Adult↗
PubMed1993

Intraoperative long-latency reflex activity in idiopathic scoliosis demonstrates abnormal central processing. A possible cause of idiopathic scoliosis.

Segmental reflex regulation in 37 patients with idiopathic scoliosis and 8 patients with nonidiopathic scoliosis was studied by recording evoked reflex muscle potentials from four muscle groups in each lower extremity during partial neuromuscular blockade. Effects on reflex activity mediated through descending systems arising in the brain stem were investigated by recording from proximal-distal and flexor-extensor muscles. Ipsilateral and contralateral long-latency complex polysynaptic activity was present in all 37 patients with idiopathic scoliosis. This reflex activity was absent in eight nonidiopathic scoliosis patients. Long-latency reflex activity may represent segmental disinhibition. The presence of long-latency reflex activity in patients with idiopathic scoliosis and the absence of this activity in nonidiopathic scoliosis patients with curves of equal magnitude demonstrates that the curve per se is not responsible for the activity. This would imply that abnormal reflex processing may play a role in the development of the spinal deformity in patients with idiopathic scoliosis.

Adolescent↗