TABLE 1.

Clinical characteristics of subjects providing tissue samples

Parameter	NVLCs	AVMs			p Value*
		Total	Unruptured	Ruptured
No. of specimens	11	20	12	8
Mean age in yrs	32.2 ± 7.0	33.2 ± 18.4	36.2 ± 16.0	28.6 ± 21.9	0.38
Sex	3 M/8 F	10 M/10 F	7 M/5 F	3 M/5 F	0.65
Lesion location					0.26
Supratentorial	11 (100)	16 (80)	11 (92)	5 (62.5)
Infratentorial	0 (0)	4 (20)	1 (8)	3 (37.5)
Lesion characteristics
Nidus size	—	1.9 ± 0.8	2.2 ± 0.6	1.6 ± 1.1	0.12
Deep venous drainage	—	6 (30)	4 (33)	2 (25)	1.0
Eloquence	—	10 (50)	6 (50)	4 (50)	1.0
Spetzler-Martin grade
Mean	—	2 ± 0.7	1.9 ± 0.7	2.1 ± 0.8	0.54
I	—	5 (25)	3 (25)	2 (25)
II	—	10 (50)	7 (58)	3 (37.5)
III	—	5 (25)	2 (17)	3 (37.5)
IV	—	0 (0)	0 (0)	0 (0)
V	—	0 (0)	0 (0)	0 (0)
Supplemental grade†
Mean	—	2.8 ± 1.1	3.3 ± 1.0	2.1 ± 0.8	0.01
1	—	2 (10)	0 (0)	2 (25)
2	—	6 (30)	3 (25)	3 (37.5)
3	—	6 (30)	3 (25)	3 (37.5)
4	—	5 (25)	5 (42)	0 (0)
5	—	1 (5)	1 (8)	0 (0)
Presenting symptom					0.01
Seizure	11 (100)	6 (30)	6 (50)	0 (0)
Headache	—	9 (45)	5 (42)	4 (50)
Altered mental status	—	4 (20)	0 (0)	4 (50)
Incidental lesion	—	1 (5)	1 (8)	0 (0)
Presurgical treatment
Embolization	—	7 (35)	3 (15)	4 (50)	0.36
Radiosurgery	—	1 (5)	0 (0)	1 (8)	0.40

— = not applicable.

Values are expressed as the mean ± standard error of the mean or as number (%).

^*Comparison between unruptured and ruptured AVMs.

^†For additional information on the supplementary grading scale, see Lawton MT, Kim H, McCulloch CE, Mikhak B, Young WL: A supplementary grading scale for selecting patients with brain arteriovenous malformations for surgery. Neurosurgery 66:702–713, 2010.