Cervical Spine MR Imaging Findings of Patients with Hirayama Disease in North America: A Multisite Study

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Fig 1.
An 18-year-old man with HD. A, Axial T2-weighted image demonstrates LOA at the C5 level. B, Neutral T2-weighted image demonstrates subtle atrophy at C5-C6. C, Flexion T2-weighted image demonstrates 6 mm of anterior dural shift with near-complete obliteration of the subarachnoid space at C5-C6.
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Fig 2.
A 20-year-old man with HD. A, Neutral axial gradient-echo image at the C5 level demonstrates subtle bilateral LOA along the lateral aspects of the lamina bilaterally and spinal cord atrophy, asymmetric to the right. B, Neutral sagittal T2-weighted image also localizes this atrophy to C5-C6. C, Flexion sagittal T2-weighted image demonstrates 2 mm of anterior dural shift. The posterior subarachnoid space is not completely obliterated, and there is no direct spinal cord compression.

Table 1:

Demographic characteristics of patients meeting clinical criteria for Hirayama disease compared with those not meeting clinical criteria

	Patients with Hirayama Disease (n = 21)	Patients without Hirayama Disease (n = 17)
Age in years^{^a} (mean) (range)	24 (17–61)	41 (15–68)
Male sex (No.) (%)	21 (100.0)	11 (64.7)
Residence in North America, (No.) (%)	21 (100.0)	16 (94.1)
White (No.) (%)	20 (95.2)	14 (82.3)
Asian (No.) (%)	0 (0)	1 (5.9)
Other or unknown race	1 (4.7)	2 (11.8)

Table 2:

Diagnostic performance of imaging attributes

	Sensitivity		Specificity		Diagnostic Odds Ratio^{^a}		P Value^{^b}
	Estimate	95% Confidence Interval	Estimate	95% Confidence Interval	Estimate	95% Confidence Interval	P Value^{^b}
Neutral MRI^{^c}	70% (14/20)	(48%–85%)	100% (17/17)	(82%–100%)	78.1	(4.0–1505.9)	<.0001
Neutral and flexion MRI	71% (15/21)	(50%–86%)	100% (17/17)	(82%–100%)	83.5	(4.3–1605.1)	<.0001
LOA on neutral images^{^c}	65% (13/20)	(43%–82%)	94% (16/17)	(73%–99%)	29.7	(3.2–273.4)	.0004
Anterior dural shift with flexion^{^d}	76% (16/21)	(55%–89%)	94% (16/17)	(73%–99%)	51.2	(5.4–488.7)	<.0001
Asymmetric cord flattening	48% (10/21)	(28%–68%)	65% (11/17)	(41%–83%)	1.7	(0.4–6.2)	.521
Cord T2 signal	33% (7/21)	(17%–55%)	94% (16/17)	(73%–99%)	8.0	(0.9–73.2)	.053
Abnormal curvature^{^c}	50% (10/20)	(30%–70%)	65% (11/17)	(41%–83%)	1.8	(0.5–6.9)	.510
C8 most affected cervical myotome at EMG with moderate-to-severe change^{^e}	50% (10/20)	(30%–70%)	88% (14/16)	(64%–97%)	7.0	(1.3–39.1)	.0317

↵a The odds ratio for neutral MRI and neutral and flexion MRI was computed by adding 0.5 to each cell (ie, the empiric odds ratio) to account for the zero cell that resulted from 100% specificity.
↵b P values were derived from a 2-tailed Fisher exact test.
↵c One patient did not have neutral images for assessment.
↵d Recorded as present, defined as any degree of dural shift, or absent.
↵e One patient did not have an EMG on record.