A multicentre retrospective review of muscle necrosis of the leg following spinal surgery with motor evoked potential monitoring: a cause for concern?

PURPOSE: 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.