Table 4.

Patients' Demographics for Each Affected Level

Factor	Upper	Middle	Lower
n	69	102	128
Sex
Male	42 (60.9%)	55 (53.9%)	69 (53.9%)
Female	27 (39.1%)	47 (46.1%)	59 (46.1%)
Mean age (yr)	51.5 ± 15.2 yr	52.2 ± 15.7 yr	53.3 ± 17.1 yr
Preoperative JOA score	5.4 ± 2.9	4.9 ± 2.6	17.3 ± 35.9 mo
Mean disease duration (mo)	20.0 ± 39.2 mo	13.6 ± 20.6 mo	6.6 ± 2.5
Postoperative JOA score	7.4 ± 2.3	6.9 ± 2.1	8.1 ± 2.2
JOA recovery rate (%)	41.8 ± 27.0	34.1 ± 19.7	39.3 ± 30.7
Initial/preoperative symptoms
Girdle pain	12 (17.4%)/15 (21.7%)	7 (6.9%)/7 (6.9%)	0 (0.0%)/0 (0.0%)
Back pain	21 (30.4%)/28 (40.6%)	24 (23.5%)/26 (25.5%)	4 (3.1%)/4 (3.1%)
Low back pain	4 (5.8%)/8 (11.6%)	9 (8.8%)/12 (11.8%)	53 (41.4%)/62 (48.4%)
Leg numbness	39 (56.5%)/49 (71.0%)	55 (53.9%)/75 (73.5%)	64 (50.0%)/85 (66.4%)
Leg pain	7 (10.1%)/9 (13.0%)	12 (11.8%)/17 (16.7%)	29 (22.7%)/39 (30.5%)
Gait disturbance	17 (24.6%)/44 (63.8%)	29 (28.4%)/79 (77.5%)	31 (24.2%)/68 (53.1%)
Leg paresis	3 (4.3%)/16 (23.2%)	7 (6.9%)/53 (52.0%)	11 (8.6%)/32 (25.0%)
BBD	1 (1.4%)/4 (5.8%)	3 (2.9%)/13 (12.7%)	5 (3.9%)/9 (7.0%)
Neurologic findings
Hyper-PTR	56 (81.2%)	82 (80.4%)	57 (44.5%)
Hyper-ATR	51 (73.9%)	74 (72.5%)	53 (41.4%)
Positive ankle clonus	38 (55.1%)	53 (52.0%)	30 (23.4%)
Disease
OLF	7 (10.1%)	3 (2.9%)	38 (29.7%)
OPLL	8 (11.6%)	19 (18.6%)	3 (2.3%)
OPLL + OLF	5 (7.2%)	18 (17.6%)	3 (2.3%)
IET	24 (34.8%)	29 (28.4%)	45 (35.2%)
IMSCT	16 (23.2%)	16 (15.7%)	32 (25.0%)
VT	7 (10.1%)	7 (6.9%)	3 (2.3%)
SCH	2 (2.9%)	5 (4.9%)	0 (0.0%)
VF	0 (0.0%)	1 (1.0%)	3 (2.3%)
TDH	0 (0.0%)	3 (2.9%)	2 (1.6%)

ATR = ankle tendon reflex, BBD = bowel bladder disturbance, IET = intradural extramedullary tumor, IMSCT = intramedullary spinal cord tumor, JOA = Japanese Orthopaedic Association, OLF = ossification of the ligamentum flavum, OPLL = ossification of the posterior longitudinal ligament, PTR = patellar tendon reflex, SCH = spinal cord herniation, TDH = thoracic disk herniation, VF = vertebral fracture, VT = vertebral tumor