Document Detail

Physiologic changes of nerve root during posterior lumbar discectomy.
MedLine Citation:
PMID:  7604340     Owner:  NLM     Status:  MEDLINE    
STUDY DESIGN AND OBJECTIVES: The effects of nerve root retraction in posterior discectomy on pressure, blood flow, and electrophysiologic changes of the nerve root were investigated. OBJECTIVES: This study was performed to assess the effects of nerve root retraction in posterior discectomy on pressure, blood flow, and electrophysiologic changes of the nerve root. SUMMARY OF BACKGROUND DATA: The effects of compression on nerve tissue have been clinically studied mainly in peripheral nerves. The potential risk for lumbar nerve root injury has not been evaluated precisely in humans. METHODS: Among 31 patients with lumbar intervertebral disc herniation, the correlation between retraction pressure and changes in blood flow of the nerve root was evaluated. Retraction pressure was continuously monitored during the discectomy and the length of the discectomy procedure was measured. Threshold and amplitude of compound muscle action potentials were monitored before and after discectomy. The relationship between intraoperative data on nerve root physiology and postoperative neurologic change was analyzed. RESULTS: Nerve root blood flow was decreased to 18-30% of the initial value under the pressure around 70 g/cm2. An abrupt decrease in nerve root blood flow was observed even within 1 or 2 mm of retraction distance. The threshold of the nerve root before retraction was minimal in the nerve root of the asymptomatic side, but increased in the affected root demonstrating sensory loss only, and significantly increased in the root showing sensory/motor deficit. Amplitude of compound muscle action potentials evoked by the stimulation at distal from herniated mass was lowest in the nerve root showing sensory/motor deficit. In 4 of 31 patients, high retraction pressure (> 170 g/cm2) was required and they showed temporary sensory deterioration after surgery. The length of discectomy procedure in these 4 patients was 14.1 +/- 4.1 minutes, but it was 9.9 +/- 2.7 minutes in the remaining 27 patients. CONCLUSIONS: In posterior lumbar discectomy, nerve root ischemia usually occurs during retraction. The magnitude of pressure and time of retraction may be potential risk factors for nerve root injury.
H Matsui; H Kitagawa; Y Kawaguchi; H Tsuji
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Spine     Volume:  20     ISSN:  0362-2436     ISO Abbreviation:  Spine     Publication Date:  1995 Mar 
Date Detail:
Created Date:  1995-08-10     Completed Date:  1995-08-10     Revised Date:  2010-03-24    
Medline Journal Info:
Nlm Unique ID:  7610646     Medline TA:  Spine (Phila Pa 1976)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  654-9     Citation Subset:  IM    
Department of Orthopaedic Surgery, Toyama Medical and Pharmaceutical University, Faculty of Medicine, Japan.
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MeSH Terms
Blood Flow Velocity / physiology
Blood Pressure / physiology
Intervertebral Disk Displacement / physiopathology,  surgery*
Lumbar Vertebrae / innervation*,  physiology,  surgery
Middle Aged
Postoperative Complications
Regional Blood Flow
Spinal Nerve Roots / blood supply,  physiopathology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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