The effect of spinal cord stimulation (SCS) on static balance and gait

OBJECTIVES

To investigate whether spinal cord stimulation (SCS) has a negative effect on static balance and gait, which is implicated by the increased incidence of falls leading to frequently occurring lead migrations.

MATERIALS AND METHODS

A controlled trial is performed with 11 subjects (four female, seven male) with a mean age of 46 years old. A baseline measurement consisting of static balance and gait tests was performed. Within two weeks after implantation of a spinal cord stimulator, subjects performed the same tests with both stimulation switched on and off. Static balance was assessed with eyes open and eyes closed on hard surface and foam surface. The velocity of the center of pressure and weight symmetry were the main outcome parameters. Kinematics and spatiotemporal outcome parameters were used to analyze gait. ANOVAs were used to compare between baseline, stimulation on, and stimulation off.

RESULTS

 Spinal cord stimulation resulted in significant pain relief as scored on a Visual Analog Scale (p < 0.001). Gait width decreased and this change (indicative of improvement in balance) was significant (p = 0.007). No other significant group differences were found between stimulation baseline and post-surgery measurements. SCS did not influence static balance or gait when group effects were analyzed. Four subjects showed significant differences in static balance between stimulation on and off.

CONCLUSIONS

 The lack of group differences in normal gait and static balance cannot explain the increased incidence of falls. However, four subjects showed an effect of SCS on static balance. Further research to clarify why only a part of the subjects experienced balance problems is recommended and assessments of more demanding balance and gait tasks are desirable.

Use of a stimulating catheter for total knee replacement surgery: preliminary results

BACKGROUND

There is continuing debate as to whether the use of electrical stimulation that aids in localizing nerves is also beneficial for optimizing placement of nerve catheters and lead to improved clinical outcomes, such as reductions in pain scores and opioid consumption.

METHODS

We undertook a retrospective, non-randomized comparison of stimulating and non-stimulating nerve catheters in 419 patients undergoing total knee replacement between December 2002 and July 2004. Before surgery, patients received sciatic and femoral nerve blocks with a catheter for the femoral nerve. In 159 patients a stimulating catheter system (Stimucath; Arrow International, Reading, PA, USA) and in 260 patients a non-stimulating catheter system (Contiplex; B. Braun, Melsungen, Germany) was used. After surgery, pain scores and morphine consumption were recorded at 4-h intervals until the first postoperative morning. In a subset of 85 patients, the postoperative evaluation period was lengthened to 3 days.

RESULTS

Postoperative visual analogue scores (VAS) for pain were similar in the two groups during the first 24 h (P=0.305). In patients followed for 3 days, VAS scores did not differ on any of the days (P=0.427). Total morphine consumption did not differ on the first postoperative day (mean [95% CI]: stimulating, 12.4 [10.1-14.7] mg; non-stimulating 10.4 [8.9-11.8] mg; P=0.140) or on subsequent days.

CONCLUSIONS

The practical advantages of the stimulating catheter, as reported by previous investigators, were not obvious in this clinical situation. In terms of outcome measures such as pain scores and morphine consumption, we found no significant differences between stimulating and non-stimulating catheters.