Table 2. Demographic and clinical features of VNS patients (N=39).

Clinical feature		n (%)	Mean ± SD	Range
Gender	Male	21 (53.8%)
	Female	18 (46.2%)
Age at seizure onset (years)			4.8±6.3	0-24
Age at VNS implantation (years)			18.1±14.2	3-56
Time elapsed from first seizure to VNS implantation (years)			13.4±11.3	2.5-53.5
Time elapsed from VNS implantation to follow up (years)			7.2±3.6	1.6-15
Etiology	Genetic	11 (28.2%)
	Structural	19 (48.7%)
	Infectious	6 (15.4%)
	Unknown	3 (7.7%)
Dominant seizure type	Focal	27 (69.2%)
	Generalized	12 (30.8%)
History of epilepsy-related surgical procedure	Yes	6 (15.4%)
	No	33 (84.6%)
Number of different AEDs prior to VNS implantation	≤5	10 (25.6%)
	6-9	20 (51.3%)
	≥10	9 (23.1%)
Behavioral disorders prior to VNS	Yes	17 (43.6%)
	No	21 (53.8%)
	Unknown	1 (2.6%)
Verbal communication status prior to VNS	Appropriately developed for chronologic age	12 (30.8%)
	Not appropriately developed for chronologic age	13 (33.3%)
	Not capable of verbal communication	12 (30.8%)
	Unknown	2 (5.1%)

VNS = vagus nerve stimulation; AED = antiepileptic drug