Clinical experience with paraspinal mapping. II: A simplified technique that eliminates three-fourths of needle...

To simplify and minimize the quantified needle examination of the paraspinal muscles (paraspinal mapping [PM]) without compromising sensitivity or specificity.

Nonrandomized prospective trial.

Electrodiagnostic laboratory of a university spine center and of a private practice in a small community.

One hundred fourteen consecutive persons referred for electrodiagnosis of spinal or lower extremity disorders who had PM data and 35 previously reported asymptomatic volunteers.

Abbreviated PM protocols were simulated by progressively eliminating data from the 45 needle insertions of the original PM. Simulations involving 35, 15, 13, and 5 insertions resulted in different normal values (95% of asymptomatic volunteers) and different scores in patients. The resulting reclassification of patients as normal or abnormal was compared with the original protocol and with clinical data.

False positive and false negative rates of the simulations compared with the original protocol.

Abbreviated protocols involving 30, 15, 13, and 5 needle insertions had normal cutoff scores of less than 5, less than 4, less than 3, and less than 2, respectively, with 2%, 2%, 4%, and 8% false positive rates and 3%, 8%, 13%, and 21% false negative rates compared with the original. In many cases clinical information correlated better with the abbreviated test results than the original PM.

The third protocol compared well with the original PM, and in a limited number of patients with imaging studies demonstrated 92% sensitivity and 92% specificity. By eliminating the iliocostalis, longissimus, and lowest multifidus needle explorations, 73% fewer needle insertions were used. We recommend that this new technique, now called "miniPM," be used in most clinical settings.