Intraoperative Monitoring of the Diaphragm Function During Cervical Dorsal Root Entry Zone-Lesioning Illustration...

Microsurgical DREZotomy (MDT) involves lesioning the dorsal root entry zone at the cervical spinal level, carrying a potential risk of iatrogenic spinal cord injury. Misidentifying the C4 root can lead to impaired diaphragmatic contractions and respiratory compromise. This report is the first MDT procedure in our Central Asian region and introduces the simultaneous analysis of 3 ventilator waveforms-capnography, pressure time, and flow time-as a novel, rapid-response intraoperative neurophysiological monitoring for definitive C4 root identification.

Traumatic brachial plexus avulsion is an upper limb injury resulting in severe complications such as paralysis and neuropathic pain. Patients with refractory, pharmaco-resistant pain may be candidates for cervical MDT. Intraoperative neurophysiological monitoring during MDT is beneficial because it allows for anatomical mapping from C4 to Th1 nerve roots. The C4 root should not be targeted during MDT because it is cardinal for diaphragmatic muscular activity. Three ventilation curves simultaneously displayed synchronous changes during C4 ventral root stimulation, indicative of phrenic excitation and the diaphragm's reaction against the anesthesia machine. The expected C4 ventral root responses completely aligned with the stimulation patterns observed across all 3 monitored parameters.

The simplicity of this method and its high practical applicability make it valuable for identifying phrenic nerve fibers during various surgical procedures where nerve roots responsible for diaphragmatic muscle contraction may be at risk.