General Session: Cervical Degenerative - Hall F

Presented by: R. Haddas

Author(s):

R. Haddas(1), K. Ju(2), R. Arakal(3), S. Hochschuler(3), T. Belanger(2)

(1) Texas Back Institute, Research Foundation, Plano, TX, United States
(2) Texas Back Institute, Rockwall, TX, United States
(3) Texas Back Institute, Plano, TX, United States

Abstract

Study Design: Non-randomized, prospective, concurrent control cohort study.

Objective: To quantify spine and lower extremity neuromuscular activity and amount of sway in cervical spondylotic myelopathy (CSM) patients while they attempt to maintain a balanced posture and compare them to age matched controls.

Background: Balance is defined as the ability of the human body to maintain its center of mass (COM) within the base of support with minimal postural sway. Sway is the movement of the COM in the horizontal plane when a person is standing in a static position.

Patient Sample: Twenty-one patients with symptomatic CSM who have been deemed appropriate surgical candidates along with 16 healthy controls (H).

Methods: All test subjects were fitted with 51 external reflective markers. Each subject performed a series of functional balance tests. Surface EMG electrodes were placed on the skin overlying the External Oblique (EO), Multifidus (Mf), Lumbar Erector Spinae (ES), Gluteus Maximus (GM), Rectus Femoris (RF), Semitendinosus (ST), Tibialis Anterior (TA), and Medial Gastrocnemius (MG). Spine and lower extremity integrated electromyography (iEMG) measurements were obtained. iEMG activity is a graphic representation of the sum total EMG activity over a defined period of time. The functional balance test was similar to a Romberg´s test in which the patients were required to stand erect with their feet together and eyes open in their self-perceived balanced and natural position for a full minute. COM and head sway was defined as the maximum displacement in the sagittal and coronal planes during the functional balance test, which was calculated using a custom algorithm. We further measured and calculated the 'total sway' by measuring the total displacement of the COM or head in the horizontal plane over the course of the one minute balance test. Data analyzed with one-way ANOVA.

Outcome Measures: Sagittal and coronal sway, total sway, and spine and lower extremity iEMG.

Results: When comparing sway, CSM patients had more horizontal sway in the coronal (CSM: 21.74 cm vs. H: 0.21 cm; p=0.050) plane compared to controls. When comparing total sway, CSM patients presented with more COM (CSM: 41.64 cm vs. H: 19.26 cm; p=0.001) and head (CSM: 35.61 m vs. H: 19.93 cm; p=0.004) displacements in comparison to controls. We also found that CSM patients exhibited significantly more muscle activity to maintain a static standing posture, as exhibited by increased muscle activity in their Mf (CSM: 26.96 mV vs. H: 8.94 mV; p=0.050), and RF (CSM: 29.64 mV vs. H: 16.07 mV; p=0.050) muscles during the one minute standing test compared to controls. Although not statistically significant, there was a trend toward greater muscle activity in the rest of the tested muscles.

Conclusions: In symptomatic CSM patients, coronal sway, COM total sway, and head total sway were significantly greater than controls. Individuals with CSM exhibit more muscle activity, particularly in the Mf and RF muscles, and thus expend more energy to maintain a balanced, standing posture. While most of the balance research in patients with spinal disorders is done based on static xrays and mostly focused on sagittal spinal alignment, this study is the first effort to evaluate global balance as a dynamic test.