title: A multicentre retrospective review of muscle necrosis of the leg following spinal surgery with motor evoked potential monitoring: a cause for concern?
abstract: OBJECTIVE
  There are very few reported cases of compartment syndrome of the leg following spinal surgery via a posterior approach. An association between compartment syndrome and muscle over-activity via nerve stimulation during evoked potential monitoring was first suggested in 2003. No further reports have suggested this link. We present a multicentre retrospective review of a series of five patients who developed compartment syndrome of the leg following spinal surgery via a posterior approach, whilst un-paralysed and with combined sensory (SSEP)/motor evoked potential (MEP) monitoring with an aim of highlighting this possible causative factor.
  
  
  METHODS
  All data were collected contemporaneously and retrospective analysis was performed. We then arranged for a multidisciplinary review of the cases including surgeons, anaesthetists, radiologists, neurophysiologists and theatre and ward nursing staff. Finally, the literature was reviewed.
  
  
  RESULTS
  All patients were operated on by three different surgeons, on different operating tables/mattresses in the prone position. The common factors were un-paralysed patients having motor/sensory monitoring, mechanical calf pumps and total intravenous anaesthesia. Three patients underwent surgical decompression of their compartments and two were treated expectantly. Three patients had confirmed intra-compartmental changes on MRI consistent with compartment syndrome and one had intra-compartmental pressure monitoring which confirmed the diagnosis.
  
  
  CONCLUSIONS
  Previous cases in the literature have related to mal-positioning on the Jackson table or use of the knee-chest position for surgery. This was not the case for our patients; therefore, we suspect an association between overactive muscle stimulation and muscle necrosis. Further experimental studies investigating this link are required.
authors.affiliation: Spinal Deformity Unit, Royal National Orthopaedic Hospital (RNOH), Brockley Hill, Stanmore, HA7 4LP, Middlesex, UK. divanik@doctors.org.uk.|, 25A Ravensdale Avenue, North Finchley, London, N12 9HP, UK. divanik@doctors.org.uk.
authors.forename: Kiran G
authors.initials: KG
authors.lastname: Divani
authors.affiliation: Spinal Deformity Unit, Royal National Orthopaedic Hospital (RNOH), Brockley Hill, Stanmore, HA7 4LP, Middlesex, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: O'Brien
authors.affiliation: Spinal Deformity Unit, Royal National Orthopaedic Hospital (RNOH), Brockley Hill, Stanmore, HA7 4LP, Middlesex, UK.
authors.forename: Sean
authors.initials: S
authors.lastname: Molloy
authors.affiliation: Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, SY10 7AG, Shropshire, UK.
authors.forename: Jayesh
authors.initials: J
authors.lastname: Trivedi
authors.affiliation: Spinal Deformity Unit, Royal National Orthopaedic Hospital (RNOH), Brockley Hill, Stanmore, HA7 4LP, Middlesex, UK.
authors.forename: Joseph
authors.initials: J
authors.lastname: Cowan
authors.affiliation: Spinal Deformity Unit, Royal National Orthopaedic Hospital (RNOH), Brockley Hill, Stanmore, HA7 4LP, Middlesex, UK.
authors.forename: Alexander
authors.initials: A
authors.lastname: Gibson
mesh_terms: D000293:Adolescent; D000768:Anesthesia, General; D002813:Chondrosarcoma / Q000601:surgery; D003161:Compartment Syndromes / Q000209:etiology*; D019054:Evoked Potentials, Motor / Q000502:physiology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D005260:Female; D006801:Humans; D007866:Leg; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000009:adverse effects* / Q000379:methods; D018482:Muscle, Skeletal / Q000473:pathology; D009336:Necrosis; D019635:Neurosurgical Procedures / Q000009:adverse effects; D056888:Patient Positioning; D016684:Prone Position; D012189:Retrospective Studies; D012600:Scoliosis / Q000601:surgery; D013125:Spinal Neoplasms / Q000601:surgery; D013131:Spine / Q000601:surgery*; D055815:Young Adult
keywords: Compartment syndrome; Spinal cord monitoring; Spinal surgery