Symptom provocation of fluoroscopically guided cervical nerve root stimulation. Are dynatomal maps identical to dermatomal maps?

STUDY DESIGN: This prospective study consisted of mechanical stimulation of cervical nerve roots C4 to C8 in patients with cervical radicular symptoms undergoing diagnostic selective nerve root block. OBJECTIVES: To document the distribution of pain and paresthesias that result from stimulation of specific cervical nerve roots and compare that distribution 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 making for patients with neck and arm pain. However, it has been observed that patients with radicular symptoms may have cervical pathology by radiographic imaging that is not corroborative, or have imaging studies that suggest a lesion at a level other than the one suggested by the patient's dermatomal symptoms. These observations may suggest that cervical dermatomal mapping is inaccurate or the distribution of referred symptoms (dynatome) from cervical root irritation is different than the sensory deficit outlined by dermatomal maps. METHODS: Inclusion criteria consisted of consecutive patients undergoing fluoroscopically guided diagnostic cervical selective nerve root blocks from C4 to C8. Immediately preceding contrast injection, mechanical stimulation of the root was performed. An independent observer interviewed and recorded the location of provoked symptoms on a pain diagram. Visual data was subsequently compiled using a 793 body sector bit map. Forty-three clinically relevant body regions were defined on this bit map. Frequencies of symptom provocation and likelihood of symptom location from C4 to C8 stimulation of each nerve root were generated. RESULTS: One hundred thirty-four cervical nerve root stimulations were performed on 87 subjects. There were 4 nerve root stimulations at C4, 14 at C5, 43 at C6, 52 at C7, and 21 at C8. Analyzing the frequency of involvement of the predetermined clinically relevant body regions either individually or in various combinations yielded more than 1,000 bits of data. Although the distribution of symptom provocation resembled the classic dermatomal maps for cervical nerve roots, symptoms were frequently provoked outside of the distribution of classic dermatomal maps. CONCLUSION: The current study demonstrates a distinct difference between dynatomal and dermatomal maps.

Regional hypothermia in response to minor injury.

Minor injuries are sometimes followed by a potentially disabling syndrome of hyperalgesia, hyperesthesia, allodynia, and sudomotor disturbance as well as, eventually, weakness, muscle atrophy, trophic skin changes, and bone and joint abnormalities. Vasomotor changes frequently present as hypothermia or hyperthermia. Most of the literature refers to this syndrome as reflex sympathetic dystrophy (RSD). To observe possible early RSD changes, we studied 1000 military recruits before and during basic training. Evaluations consisted of lower limb clinical examinations and pain assessment. Infrared images were taken of anterior, posterior, medial, lateral legs, and plantar surface of the feet. If the clinical examination suggested a possible stress fracture, a bone scan was performed. Recruits were studied before training and again each time musculoskeletal complaints arose. The controls were recruits tested before the onset of training who had no musculoskeletal complaints. Two-hundred seven soldiers were injured. Regional hypothermia was noted in 8.6% of all thermograms, with 75% on the left and 25% on the right. The most common injuries causing this phenomenon were ankle pain/sprain and minor foot stress fractures, especially the left metatarsals. Hypothermia occurred within 24 to 48 h, usually beginning in the periphery and ascending proximally, lasting a few days to 6 wk (end of study). None of the recruits developed the full syndrome of RSD during the study period. Whether the continued training, even though modified, helped to prevent this complication or the observed post-traumatic hypothermia has no relationship to RSD needs to be determined.

Lumbosacral radiculopathy screen. Optimizing the number of muscles studies.

The literature is unclear as to which muscles and how many are required for a sensitive lumbosacral radiculopathy (LSR) screen. A retrospective study of 247 electrodiagnostically confirmed LSRs in 201 patients over a 3-yr period was conducted to determine how many muscles were required to identify a LSR. All LSRs showed abnormal spontaneous activity (positive waves or fibrillation potentials) in two or more muscles innervated by the same nerve root level but different peripheral nerves. All cases were categorized by radiculopathy level, and the most frequently abnormal individual muscles were combined into different muscle screens. The frequency with which each muscle screen identified a radiculopathy was the frequency with which one or more muscles in the screen displayed abnormal spontaneous activity divided by the total number of radiculopathies. The paraspinal muscles (PM) alone identified 88% of LSRs. Without PM, two muscle screens identified only 14-68%, three muscle screens identified 37-89% and four muscle screens identified 45-92%. Including PM, three muscle screens identified 86-94% of LSRs, four muscle screens identified 91-97% and five muscle screens yielded 94-98% identification. Seven to ten muscle screens resulted in minimal improvements in identifying a LSR with 98-99% identification. We conclude that five muscle LSR screens, including PM, are sufficient to identify LSRs while minimizing patient discomfort and examiner time.