Contrasting disease patterns in seropositive and seronegative neuromyelitis optica: A multicentre study of 175 patients

Table 9 Myelitis, comparison of spinal cord MRI features according to the patients' AQP4-Ab serostatus.

	Seropositive	Seronegative	p-level
Median lesion length^†, first MRI	6 (1-21; N = 104)	4.5 (2-12; N = 26)	n.s.^§
Median lesion length^†, all MRIs	5 (1-21; N = 264)	4 (1-16; N = 47)	p < 0.01^§
SC lesions ≥ 3 vertebral segments, 1^st MRI	134/142 (94.4%)	38/40 (95%)^#	n.s.^‡
SC lesions ≥ 3 vertebral segments, all MRIs	240/274 (87.6%)	46/51 (90.2%)^#	n.s.^‡
SC lesions ≥ 6 vertebral segments, 1st MRI	63/115 (54.8%)	10/28 (35.7%)	n.s.^‡
SC lesions ≥ 6 vertebral segments, all MRIs	131/264 (49.6%)	12/47 (25.5%)	p < 0.003^‡
Patients with entire SC involvement at least once	15/132 (11.4%)	0/36 (0%)	p < 0.043^‡
MRIs with more than one lesion	59/274 (21.5%)	9/51 (17.6%)	n.s.^‡
Total lesion load*, first MRI	6.5 (1-21; 104)	5 (2-12; 26)	p < 0.022^§
Total lesion load*, all MRIs	6 (1-21; 264)	5 (1-16; 47)	p < 0.006^§
Total lesion load > 6 segments*, first MRI	65/104 (62.5%)	11/26 (42.3%)	n.s.^‡
Total lesion load > 6 segments*, all MRIs	153/264 (58%)	17/47 (36.2%)	p < 0.007^‡

Values are given as median (range, number) or as proportions. ^†If more than one lesion was present in the same MRI, the longest lesion was counted. *Median cumulative length of all lesions present in the same spinal cord MRI. ^#Note that all seronegative patients with NMO according to Wingerchuk 2006 or LETM had lesions extending over 3 or more vertebral segments at least once per definitionem. ^‡Fisher's exact test (2-tailed). ^§ Mann Whitney U test. MRI = magnetic resonance imaging; N = number of patients (not all data were available from all patients); n.s. = not significant; SC = spinal cord.

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