Recovery of zero-grade muscles in the zone of partial preservation in motor complete quadriplegia.

This prospective study was designed to demonstrate root level recovery in the zone of preservation by examining muscles with an initial strength of grade 0/5 in 32 motor complete (Frankel A and B) patients who had cervical spinal cord injury at the C4 through C7 levels. The biceps (C5), extensor carpi radialis (C6), triceps (C7), and flexor digitorum profundus (C8) muscles were used as key muscles when their strength at the initial manual muscle test, which was performed between three and seven days postinjury, was grade 0/5 and the muscle innervated by the cord segment directly rostral to that innervating the key muscle (grade 0/5) was grade greater than or equal to 3/5. If the biceps muscle was used, C4 pin sensation was required to be normal. Further manual muscle tests were performed weekly for four weeks, and then at 2, 3, 6, and 12 months postinjury. None, 6%, 17%, 35%, and 43% of the patients recovered to grade greater than or equal to 3/5 by 1, 2, 3, 6, and 12 months postinjury, respectively. It was also noted that in 86% of our patients, improving to grade greater than or equal to 1/5 by one month postinjury was a predictor of recovering to grade greater than or equal to 3/5 by 12 months postinjury (p less than .002). Similarly, in 100% of our patients, improving to grade greater than or equal to 2/5 by three months postinjury was a predictor of recovering to grade greater than or equal to 3/5 by 12 months postinjury (p less than .001).(ABSTRACT TRUNCATED AT 250 WORDS)