A new method for characterizing hand dysfunction in cervical spondylotic myelopathy: a preliminary study.

Study Design: A case-control investigation.

Objectives: The objective of this study was to quantitatively study impaired ability to appropriately adjust pinch strength while holding a small object in patients with cervical spondylotic myelopathy (CSM).

Setting: Kochi Medical School Hospital, Japan.

Methods: The subjects consisted of 19 CSM patients who had frequent episodes of failing to grasp and hold small objects in their daily life (Group A), 13 CSM patients who did not experience such episodes (Group B) and 16 healthy subjects (Control Group). We continuously measured the dynamic internal pressure of a pneumatic rubber object called a blower pinched by the subject, following two different sets of instructions: (1) pinching with eyes open and with the minimal strength required to prevent dropping; and (2) maintaining a constant pinch strength at given levels with eyes closed.

Results: Compared with the other two groups, Group A subjects used a significantly (P<0.01) greater pinch strength to avoid dropping the blower held with eyes open and showed a significantly (P<0.01) greater deviation in pinch strength from the baseline values with eyes closed. These tendencies in Group A showed a significant correlation with the tactile perception threshold of the digits (P<0.01) but not with impairment of rapid repetitive movements of the digits that reflects spasticity.

Conclusion: Our technique applied to CSM patients helps assess functional integrity primarily, if not exclusively, of the fasciculus cuneatus mediating the feedback signals from proprioceptive and cutaneous receptors in the digits, which are otherwise difficult to evaluate quantitatively.