Dermatomal Contact Heat Evoked Potentials for the Detection of Subclinical Cervical Spinal Cord Injury in...

Asymptomatic degenerative cervical cord compression (ADCC) represents a premyelopathic stage of degenerative cervical myelopathy (DCM), with high prevalence in older age and unclear management. Contact heat-evoked potentials (CHEPs) assess the integrity of the thermo-algesic somatosensory pathway and have shown the highest sensitivity among neurophysiological methods in detecting dysfunction in the centromedial and anterior spinal cord in DCM.

This cross-sectional cohort study evaluated the utility of upper extremity dermatomal C4, C6 and C8 CHEPs (dCHEPs) compared to standard neurophysiological methods-median and tibial nerves somatosensory evoked potentials (SEPs), upper and lower extremity motor evoked potentials (MEPs), and electromyography (EMG)-for detecting subclinical cervical cord dysfunction in ADCC. Two cohorts were included: 82 ADCC patients (mean age 53.7 ± 9.8 years; 53 females) and 10 DCM patients (mean age 64.0 ± 7.9 years; 4 females). All underwent bilateral dCHEPs (C4, C6, C8), SEPs, MEPs, and EMG (C5-C8 myotomes).

dCHEPs abnormalities were found in 50% of ADCC patients, exceeding the rates for SEPs (32.1%), MEPs (21.8%), and EMG (13.9%). In 20.7%, dCHEPs were the only abnormal neurophysiological finding. In the DCM cohort, dCHEPs were abnormal in 80%, and were the only abnormality in 20%. In both groups, abnormalities were most frequent in the C8 dermatome.

dCHEPs demonstrated superior sensitivity in detecting cervical cord dysfunction, not only in DCM but also in ADCC. As a functional complement to MRI, they may aid in identifying early spinal cord involvement. Their prognostic role in ADCC warrants further study.