Study Design
Prospective cohort study
Objective
To assess the correlation between central motor conduction time (CMCT) and
various subjective and objective clinical assessment measures in patients with cervical
spondylotic myelopathy (CSM) undergoing decompressive surgery
Summary of Background Data
CSM can cause a spectrum of neurological deficits across individuals.
Subjective clinical assessments of disease severity may lack the sensitivity of
objective tests. Transcranial magnetic stimulation (TMS) provides objective
electrophysiologic data on the integrity of the corticospinal tracts, which may be
useful for monitoring disease progression or neurological improvement after surgery.
Methods
Patients undergoing surgical decompression for CSM performed subjective and
objective testing before surgery and at 1, 3, 6 and 12 months after surgery. Subjective
measures included modified Japanese Orthopaedic Assessment (mJOA), Neck Disability Index
(NDI), Nurick grade, and visual analog scale (VAS) score. Objective measures included
CMCT as measured using TMS, the 10-meter walk test (10MWT), the 9-hole peg task (9HPT),
and grip and release test (GRT). Primary outcome was the correlation between CMCT and
subjective or objective measures at preoperative and postoperative time points.
Secondary outcome was the correlation between preoperative CMCT and performance in
subjective or objective testing after surgical intervention.
Results
Improvement in both subjective and objective measures was observed after
surgery. CMCT correlated with other objective measures (10MWT, 9HPT, and GRT) both at
baseline and after decompressive surgery in these 17 patients with CSM. Patients with
high baseline CMCTs were associated with poor performance on the 10MWT, 9HPT, and GRT.
mJOA correlated with CMCT at baseline but not after surgical intervention. CMCT was not
associated with other subjective measures, such as NDI, Nurick grade, and VAS, at
preoperative or postoperative time points.
Conclusion
CMCT as measured by TMS is a responsive objective assessment of CSM. It can be
used to monitor disease severity and neurological function before and after surgical
intervention. Prolonged baseline CMCT may be associated with worse surgical
outcomes.