Effects Of Developmental Canal Stenosis On Thoracic Ossification Of The Ligamentum Flavum:age Of Onset And Duration Of Symptoms

Objective:To investigate the effects of congenitally stenotic canal on thoracic ossification of the ligamentum flavum(OLF),including age of onset and duration of symptoms.Methods:Thoracic canal parameters were measured based on computed tomography including spinal canal depth(SCD),spinal canal width(SCW)and spinal canal area(SCA)from 50 patients of control group.At each level,the SCA values of the control group two SDs below the mean were considered congenital stenosis.According to this standard,50 patients with thoracic OLF-induced myelopathy were divided into 2 groups: Group P(positive with congenital thoracic stenosis)and Group N(negative with congenital thoracic stenosis).The duration and age at onset of 2 groups were compared and analyzed.Results :At each level,congenital canal stenosis was defined as:T1,137.98mm2;T2,128.07mm2;T3,120.65 mm2;T4,124.50 mm2;T5,120.24 mm2;T6,121.89mm2;T7,121.13 mm2;T8,122.05 mm2;T9,116.62 mm2;T10,119.12 mm2;T11,128.89 mm2;T12,163.70mm2.Congenital canal stenosis was found in 58.0% of all cases.Groups P(positive)and N(negative)was comprised 29 and 21 patients,respectively.Compared with Group N,Group P had significantly smaller SCD(spinal canal depth)and SCA(spinal canal area),whereas,all of them had a similar SCW(spinal canal width).The age of onset in Group P(51.98± 9.33 years)was much younger than that in Group N(59.4 ± 8.36 years),the differences were statistically significant(t=13.475,p<0.05).The mean duration of symptoms was 34.74 ± 39.05 and 23.62 ± 32.69 months in Groups P and N,respectively.There was no significant difference in duration of symptoms(t=?0.961,p>0.05).Conclusion:Patients with thoracic OLF-induced myelopathy tend to coexisted with congenital canal stenosis.Patients with congenitally narrow canal have a younger age of onset.Patients with/without congenital stenosis have a similar duration of symptoms.