AN ELECTROPHYSIOLOGICAL INVESTIGATION OF THE MOTOR SYSTEM IN IDIOPATHIC SCOLIOSIS

Abstract

Introduction: Immature individuals with known neuromotor disorders are subject to the development of scoliosis; therefore a subclinical dysfunction or anatomic abnormality of the neurologic system has been hypothesized as a causative factor of adolescent idiopathic scoliosis.

In previous clinical studies, authors have tested a wide range of functions, including proprioception, postural equilibrium, oculovestibular complex and vibratory sensation and multiple techniques, including electronystagmography, electroencephalography and electromyography in select scoliotic patient populations

Material and Methods: The present study was designed to investigate the motor system of scoliotic patients with magnetic stimulation. female patients 12 to 14 years old (mean age=13.36) with right idiopathic scoliosis (curves:20–40°) (study group) and 20 normal subjects in the same age group (mean age=12.6) (control group) entered the study. Magnetic stimulation of the brain was performed with a figure of eight coil angled 45° to the parasagittal plane and positioned so as to overly the hand area.

Transcranial stimulation was performed with a Magstim 200 stimulator (Magstim Co, Dyfed, Wales). Stimulation was performed with a figure of 8 coil for upper limbs and a double cone coil for lower limbs. Recordings were made with surface electrodes from 1st dorsal interosseous and abductor hallucis muscles. Threshold measurements included upper (UT) and lower threshold (LT), defined as the stimulus intensities producing MEPs with a propability of 100 and 0%, respectively. Mean threshold (MT) was the mean of UT and LT. Cortical latencies of MEP’s during muscle activation were also measured.

Results: In the patients’ right hemisphere UT,MT and LT were 46.5±8.2, 41.6±7.6 and 36.6±7.3% respectively and the activated cortical latency was 18.6±l.lms.

In the left hemisphere UT, MT and LT were 45.9±9.8, 41.4±9.1 and 36.9±8.7%, respectively and the activated cortical latency was 18.3±0.8ms. These differences were not statistically significant (p> 0.05, t-test). The side-to-side difference of UT,MT and LT were 4.5±2.4, 4.3±2.8 and 4.4±3.7.

None of all the above parameters differed significantly from those of the control group (p> 0.05, t-test).

The differences in the corticomotor excitability in the upper and lower extremities were not statistical significant.

Conclusion: In the study group revealed asymmetries between left and right hemisphere in cortical latencies of MEP’s facillitated.