Histological type of focal cortical dysplasia is associated with the risk of postsurgical seizure in children and adolescents

Figures & data

Table 1 Characteristics of patients

	All (n=92)
Gender
Male: Female	59:33
Median age at seizure onset, years (range)	5 (0–15)
Median age at epilepsy surgery, years (range)	13 (3–17)
Median epilepsy duration, years (range)	6 (0–17)
Median follow-up duration^a, months (range)	24 (12–48)
Number of patients with preoperative GTCs (%)	62 (67.4)
Seizure frequency before surgery
Daily (%)	43 (46.7)
Weekly (%)	15 (16.3)
Monthly (%)	31 (33.7)
Sporadic (%)	3 (3.3)
MRI lesions
Present (%)	53 (57.6)
Absent (%)	39 (42.4)
Scalp EEG findings
Regional or lateralized (%)	83 (90.2)
Generalized (%)	9 (9.8)
Number of patients with invasive EEG recording (%)	62 (67.4)
Type of surgery
Standard anterior temporal lobectomy (%)	18 (19.6)
Unilobar resection (%)	41 (44.6)
Multilobar resection (%)	30 (32.6)
Hemispherectomy (%)	3 (3.3)
Extent of resection
Complete (%)	81 (88.0)
Incomplete (%)	11 (12.0)
FCD subtype
FCD I (%)	34 (37.0)
FCD II (%)	20 (21.7)
FCD III (%)	38 (41.3)

Note: ^aFollow-up duration indicated the time from at 3 months after surgery till the latest yearly evaluation.

Abbreviations: EEG, electroencephalography; FCD, focal cortical dysplasia; GTCs, generalized tonic-clonic seizure; MRI, magnetic resonance imaging.

Figure 1 Kaplan-Meier analysis of the time to the first postsurgical seizure in the population overall (A) and by FCD types (B). The P-value was calculated from a log-rank test.

Abbreviation: FCD, focal cortical dysplasia.

Table 2 Univariable analysis of risk factors for postoperative seizure

Variable	Seizure free	Seizure relapse	P-value
FCD type			0.02
FCD I	12 (35.3)	22 (64.7)
FCD II	14 (70.0)	6 (30.0)
FCD III	23 (60.5)	15 (39.5)
Extent of resection			0.07
Incomplete	3 (27.3)	8 (72.7)
complete	46 (56.8)	35 (43.2)
Invasive EEG recording			0.03
Used	28 (45.2)	34 (54.8)
not used	21 (70.0)	9 (30.0)
MRI lesions			0.02
Absent	15 (38.5)	24 (61.5)
present	34 (64.2)	19 (35.8)

Notes: Data are No. (%) unless otherwise indicated. P-value was determined by Pearson X² or Fisher’s exact tests as appropriate.

Abbreviations: EEG, electroencephalography; FCD, focal cortical dysplasia; MRI, magnetic resonance imaging.

Table 3 Multivariable analysis of risk factors for postoperative seizure

Variable	Hazard ratio	95% CI	Adjusted P-value
FCD subtype^a
FCD I	/	/	/
FCD II	0.39	0.16–0.98	0.04
FCD III	0.78	0.37–1.61	0.50
Incomplete resection	3.04	1.36–6.76	0.01
Invasive EEG recording	2.55	1.10–5.91	0.03

Notes: ^aFCD type I served as control. The variable that was included in the model but lost its significance was the absence of MRI lesions (adjusted P-value =0.50).

Abbreviations: EEG, electroencephalography; FCD, focal cortical dysplasia; MRI, magnetic resonance imaging.