The Incidence of Bite Injuries Associated with Transcranial Motor-Evoked Potential Monitoring

Abstract

Bite injuries associated with transcranial electric stimulation are an uncommon but disturbing complication of TcMEP monitoring occurring with an incidence of 0.63% (95% confidence interval: 0.52%-0.76%), the most severe of which requiring sutures at an incidence of 0.14% (95% confidence interval: 0.09%-0.21%). Injuries of the tongue occur approximately 4 times as frequently as injuries of the lip. Despite placement of bite blocks, shifting of the bite block during stimulation or positioning is a possible cause of failure. High-intensity transcranial stimulation may increase the risk of bite injuries. We suggest consistent use of properly sized and secured bite blocks with periodic inspection to minimize risk of bite injuries. Future study is needed to determine optimal bite block configuration.

Principles of intraoperative neurophysiological monitoring and anaesthetic considerations

“…Tamkus et al reported an incidence of 0.63% and, although this is low, the use of bilateral soft bite blocks and checking for displacement throughout surgery is strongly recommended. 4,5 Intraoperative EMG techniques Free-run EMG (FrEMG) is a technique that evaluates the function of motor root axons by recording electromyographic (EMG) activity from the muscle fibres innervated by the axons of the root under exploration. It is used to detect motor nerve root mechanical activation and compromise during surgical procedures involving placement of pedicle screws, decompression for spinal stenosis where roots are at risk, correction for scoliosis deformity, radiculopathy secondary to disc herniation and/or spondylosis and removal of tumours involving the nerve roots.…”

Macroglossia in neurosurgery

“…[27] The bite block can move during patient positioning and should be secured to prevent dislodgement and should again be periodically inspected during the case. [28] Although bite blocks are used to prevent injury to the tongue and macroglossia, they can also cause trauma. [29] The position of the bite block should be inspected to ensure that the tongue and the lips are clear of the teeth and not trapped by the bite block.…”

How to Make a Do-It-Yourself, Disposable Bite Guard Using Easily Available Materials, to Prevent Tongue and Lip Injuries, During Motor Evoked Potential Monitoring in Neurosurgery

“…Intraoperative neurophysiological monitoring is increasingly used as a standard adjunct to prevent inadvertent neurological injury during cranial and spinal surgical procedures. Tongue and lip injuries due to bites while eliciting transcranial electrical stimulation for recording intraoperative motor evoked potential (TcMEP), have an incidence ranging from 0.2 to 0.63 % [1]. Rarely, even fractures of the incisor teeth have been described [1].…”

“…Tongue and lip injuries due to bites while eliciting transcranial electrical stimulation for recording intraoperative motor evoked potential (TcMEP), have an incidence ranging from 0.2 to 0.63 % [1]. Rarely, even fractures of the incisor teeth have been described [1]. Correct placement of an appropriately sized bite guard protects against this hazard to a great extent, though there is no consensus on the number or configuration of bite guards that need to be placed.…”