SYMPTOM PROVOCATION OF FLUOROSCOPICALLY GUIDED CERVICAL NERVE ROOT STIMULATION - ARE DYNATOMAL MAPS IDENTICAL TO DERMATOMAL MAPS

Study Design. This prospective study consisted of mechanical stimulati on of cervical nerve roots C4 to C8 in patients with cervical radicula r symptoms undergoing diagnostic selective nerve root block. Objective s. To document the distribution of pain and paresthesias that result f rom stimulation of specific cervical nerve roots and compare that dist ribution to documented sensory dermatomal maps. Summary of Background Data. Cervical dermatomes were first studied in the late 19th century. The results of those studies underpin current clinical decision makin g for patients with neck and arm pain. However, it has been observed t hat patients with radicular symptoms may have cervical pathology by ra diographic imaging that is not corroborative, or have imaging studies that suggest a lesion at a level other than the one suggested by the p atient's dermatomal symptoms. These observations may suggest that cerv ical dermatomal mapping is inaccurate or the distribution of referred symptoms (dynatome) from cervical root irritation is different than th e sensory deficit outlined by dermatomal maps. Methods. Inclusion crit eria consisted of consecutive patients undergoing fluoroscopically gui ded diagnostic cervical selective nerve root blocks from C4 to C8. Imm ediately preceding contrast injection, mechanical stimulation of the r oot was performed. An independent observer interviewed and recorded th e location of provoked symptoms on a pain diagram. Visual data was sub sequently compiled using a 793 body sector bit map. Forty-three clinic ally relevant body regions were defined on this bit map. Frequencies o f symptom provocation and likelihood of symptom location from C4 to C8 stimulation of each nerve root were generated. Results. One hundred t hirty-four cervical nerve root stimulations were performed on 87 subje cts. There were 4 nerve root stimulations at C4, 14 at C5, 43 at C6, 5 2 at C7, and 21 at C8. Analyzing the frequency of involvement of the p redetermined clinically relevant body regions either individually or i n various combinations yielded more than 1,000 bits of data. Although the distribution of symptom provocation resembled the classic dermatom al maps for cervical nerve roots, symptoms were frequently provoked ou tside of the distribution of classic dermatomal maps. Conclusion. The current study demonstrates a distinct difference between dynatomal and dermatomal maps.