Visually Assessed Severity of Lumbar Spinal Canal Stenosis

Results

Clinical Characteristics, Preoperative Symptoms, and Functional Disability

Patient characteristics are summarized in Table 1. The mean age of the study patients (n = 80) at the time of surgery was 63 years (11) [mean (SD)], and 35 (44%) of the subjects were male. Ten patients (13%) had undergone previous spine operation. Coexisting disc herniation was found in 11 patients (14%). According to the ODI scores 7 (9%), 26 (33%), and 36 (45%) had minimal, moderate, and severe disability, respectively, and 11 (14%) patients were crippled. Regarding the overall VAS scores, 28 (35%) patients had minimal pain, 20 (25%) had moderate pain, 22 (28%) had severe pain, and 10 (13%) had crippled pain. Regarding the BDI scale, 63 patients had normal mood and 17 patients were depressed (15 or more points); the mean BDI was 10.4 (6.1). Mean walking distance achieved was 545 (445) m (range, 0–1000 m).

Radiological Findings

According to the visual assessment, none of the patients had a normal central canal. The central canal was moderately and severely stenosed in 36 (45%) and 44 (55%) patients, respectively. Based on the quantitative assessment, the mean minimal dural sac area was 56.1 (21.9) (range, 12–120) mm². In the quantitative analyses the smallest dural sac was greater than 100 (75–100) mm², and under 75 mm² in 4 (5%), 15 (19%), and 61 (76%) patients, respectively.

Correlation of Imaging Findings With Preoperative Symptoms and Functional Disability

The correlation of radiological spinal stenosis and clinical symptoms is summarized in Table 1. VAS leg pain was higher in patients with moderate stenosis than in patients with severe stenosis (7.33 (2.29) vs 5.80 (2.72); P = 0.008) (Figure 2). The walking distance achieved was shorter in patients with radiologically moderate stenosis than in patients with severe stenosis (421 (431) m vs 646 (436) m; P = 0.021) (Figure 3). Patients with severe stenosis at only one level (50%) achieved shorter walking distance than patients with severe stenosis of at least two levels [393 (436) m vs 675 (423) m; P = 0.022]. No correlation was found between the dural sac area measurements and patient symptoms or walking distances achieved (Table 2).

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Figure 2.

Visual assessment of the MRI and VAS leg pain n = 80. Mean visual analog scale (VAS) leg pain ±1 standard deviation.

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Figure 3.

Walking distance in the treadmill exercise test in patients with moderate and severe spinal stenosis. Mean walking distance ±1 standard deviation.

Table 1. Clinical characteristics of the study subjects
	All patients (n = 80)	Moderate stenosis (n = 36)	Severe stenosis (n = 44)	P-value
Male/female	35/45 (43/56)	18/18 (50/50)	17/27 (39/61)	0.308
Marital status married or co-habiting	52 (65)	25 (69.5)	27 (61.3)	0.762
Current smoker	17 (21.3)	10 (27.7)	7 (16.0)	0.345
Previous lumbar operation	11 (13)	6 (16.7)	5 (11.4)	0.248
Depressed³	17 (21)	6 (16.7)	11 (25.0)	0.365
Minimal dural sac area^†	56.1 (21.9)	72.1 (18.0)	43.0 (15.2)	0.000
Age	63.0 (11.0)	62.0 (11.6)	64.0 (10.8)	0.413
BMI (kg/m²)	29.6 (4.0)	29.5 (4.4)	29.8 (3.5)	0.746
Number of somatic diseases	5.3 (3.0)	5.6 (3.2)	5.1 (2.8)	0.445
ODI	44.7 (16.1)	45.4 (18.0)	44.1 (14.4)	0.731
VAS overall	33.3 (23.9)	34.6 (24.7)	31.9 (25.0)	0.523
NRS LBP	4.1 (2.6)	4.72 (2.6)	3.59 (2.4)	0.059
NRS LP	6.49 (2.6)	7.33 (2.29)	5.80 (2.72)	0.008
BDI score	10.4 (6.1)	9.78 (6.86)	10.93 (5.546)	0.233
Walking distance (m)	545 (445)	421 (431)	646 (436)	0.021
Foraminal stenosis (normal/moderate/severe)^§		53/39/8	55/36/9	0.971
Multilevel stenosis yes/no^§		53/47	70/30	0.104
Lumbar fusion yes^§		33	66	0.258

Note: Except where indicated, data are numbers of patients, with percentages in parentheses or means, ± standard deviations in parentheses.
³BDI 15 or more points, ^†at the most stenotic level, mean (mm²), ± standard deviations in parentheses. ODI = Oswestry Disability Index (0–100), VAS overall = Visual analog pain scale (0–100), NRS LBP = Numerical rating scale low back pain at rest, scale (0–10), NRS LP = Numerical rating scale leg pain at walking, scale (0–10), BDI = Beck Depression Inventory (0–63), ^§Percentages.

Table 2. Correlation of the dural sac area with patient symptoms and walking capacity
	ODI scale	VAS overall scale	NRS LBP	NRS LP	Beck depression index	Treadmill test
Central spinal canal (mm2)	r = 0.086	r = −0.036	r = −0.004	r = 0.023	r = −0.099	r = −0.145
	P = 0.448	P = 0.752	P = 0.972	P = 0.841	P = 0.380	P = 0.200

r = Spearman correlation coefficients.
P = P values.
ODI = Oswestry Disability Index (0–100).
VAS overall = Visual analog pain scale (0–100).
NRS LBP = Numerical rating scale low back pain at rest (0–10).
NRS LP = Numerical rating scale leg pain at walking (0–10).
Treadmill exercise test (0–1000 m).
BDI = Beck Depression Inventory (0–63).