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
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.
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.
The fact that many patients with idiopathic scoliosis appear to be out of balance, has led many researchers to postulate that a brain stem abnormality involving the vestibular system in the cause of this condition.
An electronystagmographic study of labyrinthine function with caloric stimulation was performed in all patients. The nystagmus was recorded with the electronystagmographic technique (ENG) using Hartmann device. The recordings were performed in a dark, silent room with the tested subject in the supine position and with it’s eyes closed. We evaluated: the frequency, the amplitude and the slow phase velocity of nystagmus. The differences in labyrinthine sensitivity were evaluated with the use of unilateral weakness parameter, while differences in left – and right – beating nystagmus evaluated by estimating the directional preponderance parameter.
Nineteen patients from the study group (44.2%), revealed unilateral weakness (difference between left and right labyrinth >
20%) of the left labyrinth. Seventeen patients from the study group (39.5%) revealed directional preponderance of the right-beating nystagmus. These differences were statistical significant (p<
0.05, Chi-Square test). Seventeen patients from the study group revealed both left unilateral weakness and directional preponderance of the right labyrinth, while two patients revealed only left unilateral weakness. A significant correlation was found between the degree of the curvature and the percentage of unilateral weakness.