New method of assessing outcome of treatment for cervical myelopathy (M/T method) — preliminary report

Abstract

In some patients with cervical radiculomyelopathy, neurological examination reveals extreme muscle weakness in an upper extremity with no, or a relatively insignificant, sensory deficit. In assessment of treatment outcome in these patients, the previous method used is thought to be unsuitable. We developed a new method of assessment (the M/T method) in which the recovery of upper extremity muscle weakness is assessed. The purpose of this study was to evaluate this new method. In the M/T method, change in the function of the spinal cord, including the anterior root, is expressed as an index number (recovery rate) in relation to the time-course. The function of the nerve tissue is expressed as the value for the manual muscle testing (MMT) of muscle power, and the muscle tested is represented by one that has the least MMT value before treatment. The unit of measurement of the time-course is 3 months. The index is the difference between the MMT value at the time of follow-up and that before treatment, divided by the number of time units after treatment. The index can be expressed in both fractional and decimal forms. Fractions are useful for examining an individual patient’s progress and the decimal form is useful for comparing the data of multiple patients. The M/T method was employed in 16 patients (13 men, 3 women; age, 45–79 years; follow-up, 6 months — 8 years) whose chief complaints were muscle weakness in the upper extremities and who had undergone double-door laminoplasty. Seven patients had an M/T index of 1 or more; the score was 4 in one patient, 2 in four patients, and 1 in two patients. Two patients had an M/T index between 0 and 1; 0.17 and 0.25. Five patients had an index value of 0. The M/T index in two patients was less than 0; −0.17 and −0.11. Using the M/T method, recovery can be presented as an index number, and as a result, it is easy to compare differences in the recovery rate among patients. The M/T method is useful for evaluation of the viability of the spinal cord, including the anterior root; in particular for those patients in whom neurological examination reveals extreme muscle weakness in an upper extremity with no, or a relatively insignificant, sensory deficit.