OBJECTIVETo investigate the abnormality of position of the cerebellar tonsil and somatosensory evoked potentials (SEP) in adolescent idiopathic scoliosis (AIS), and to explore its clinical significance.

METHODSSagittal magnetic resonance imaging (MRI) of hindbrain and posterior tibial nerve SEP (PTN-SEP) were performed on 171 young operative treated AIS patients. The PTN-SEP obtained from 45 age-matched healthy control individuals were considered as standard values. Tonsillar ectopia (TE) was defined as any inferior displacement of the tonsils. Absence of SEP waveforms, prolongation of peek latency or asymmetrical peek latency were defined as pathological change. The incidence of TE and pathological SEP was determined in all AIS patients. The association of TE and abnormal SEP for AIS patients was also assessed.

RESULTSThe incidence of TE and abnormal SEP in AIS patients was 36.8% (63/171) and 36.3% (62/171), respectively. It was shown the frequency of TE and abnormal SEP were not significantly different among AIS patients with different curve severity. Statistical analysis failed to show a correlation between TE and abnormal SEP.

CONCLUSIONSTE and disorder of somatosensory pathways do exist in a subgroup of AIS patients. However, there is not a significant association between TE and abnormal somatosensory function. It is suggested that TE and disorder of somatosensory function might contributes to different etiopathogenesis of AIS.