Comparison of somatosensory evoked potentials between adolescent idiopathic scoliosis and congenital scoliosis without neural axis abnormalities.

BACKGROUND CONTEXT

Abnormal somatosensory evoked potentials (SEPs) have been documented in patients with adolescent idiopathic scoliosis (AIS) with different cure severity. However, few studies investigated whether abnormal SEPs were the cause or effect of idiopathic scoliosis.

PURPOSE

The purpose of this study was to investigate the significance of abnormal SEPs in patients with AIS, and to explore its effect on the etiopathogenesis of AIS.

STUDY DESIGN/SETTING: This study evaluated SEPs in patients with AIS and congenital scoliosis (CS) with similar curve pattern and severity both in coronal and sagittal planes.

PATIENT SAMPLE

Female patients with AIS and CS in our spine surgery center from 2000 to 2009 were recruited for this study.

OUTCOME MEASURES

Rate of abnormal SEPs.

METHODS

Posterior tibial nerve SEPs (PTN-SEPs) were performed on female patients with AIS and CS. The inclusion criteria were patients with AIS with a Lenke type 1 curve and patients with CS with right thoracic curve (apex between T5 and T12) and normal sagittal profile (kyphosis less than 50° measured from T2 to T12). All patients were evaluated with total spine magnetic resonance imaging, and those with neural axis abnormalities were excluded. The patients with neurological deficits on detailed physical examination were also excluded. Absence of SEPs waveforms or prolongation of peak latency or asymmetrical peak latency were defined as pathological change. The incidence of pathological SEPs and clinical characteristics were compared between patients with AIS and patients with CS.

RESULTS

Forty-six patients with AIS and 33 patients with CS were included in this study. There was no significant difference in coronal and sagittal Cobb angle between the two groups. The rate of abnormal SEPs was 32.6% (15/46) and 12.1% (4/33) in AIS and CS groups, respectively, and the difference was statistically significant (p<.05).

CONCLUSION

Somatosensory pathway dysfunction could be found in both AIS and CS without neural axis abnormalities, and the patients with AIS tended to have higher rates of somatosensory disorders than patients with CS with similar scoliosis curve, which indicates that both scoliosis curve and primary etiopathogenic factor contribute to the sensory deficit in patients with AIS.