Identifying the affected hemisphere with a multimodal approach in MRI-positive or negative, unilateral or bilateral temporal lobe epilepsy

Figures & data

Table 1 Patient characteristics and subgrouping

Pt no	Sex/age/duration (years)	MRI	MRS (ipsilat/contra)	Other imaging	EEG (IED/ictal)	icEEG (IED/ictal)	Seizure focus (resection)	Histopathological findings	Outcome (Engel)
MRI-positive unilateral TLE
1	M/22/10	R HS	NAA↓Cr↑		R temp/R temp		R temp and front	R HS + MCD	I
2	M/22/16	L HS	NAA↓		L temp/L temp		L temp	L HS + MCD	I
3	F/28/15	R HS	NAA↓Cr↑		R temp and front/R temp		R temp and front	R HS + MCD	I
4	M/13/10	L TA	NAA↓Cr↑		B temp and L front/L temp		L temp	L tumor	I
5	M/54/26	L HA	NAA↓Cr↑		L temp/L temp		L temp	L MCD	I
6	F/40/13	L HA	NAA↓/Cho↑		B temp and R front/L temp and front		L temp	L HS + MCD	I
7	M/38/28	R HA	NAA↓Cr↑		B temp/R temp		R temp	R HS + MCD	II
MRI-positive bilateral TLE
8	M/14/9	B HS	/NAA↓		B temp/B temp (L origin)		L temp	L HS + MCD	II
9	M/19/15	L HA	NAA↓Cho↑/NAA↓		L temp/B temp	L temp/B temp (L)	L temp	L HS + MCD	I
10	M/23/9	L HA	NAA↓Cr↑/NAA↓		B temp and front/B front	B temp and front/L temp and front	L temp and front	L HS + MCD	II
11	M/28/28	B TA	NAA↓		B temp and front/B temp (L origin)	B temp/B temp (L)	B temp (L temp)	L MCD	II
MRI-negative unilateral TLE
12	M/9/7	0	Cho↑/NAA↓		B temp/L temp and front		L temp and front	L HS + MCD	I
13	F/31/20	0	NAA↓		B temp and front/L temp and front	B temp/L temp	L temp	L HS + MCD	I
14	M/19/6	0	NAA↓Cr↑		L temp/L temp		L temp (Na)	Na	Na
15	F/18/2	0	NAA↓Cr↑		B temp and R parietal/L temp		L temp	L HS + MCD	I
16	M/28/5	0	Cho↑/NAA↓		B temp and front/L temp	L front/L front and temp	L front and temp (L front)	L MCD	I
MRI-negative bilateral TLE
17	M/33/22	0	Cho↑/NAA↓		B temp/B temp	B temp/R temp	B temp (R temp)	R HS + MCD	III
18	F/42/10	0	Cho↑/NAA↓		L temp/B temp		L temp and front	L HS	I
19	M/29/3	0	NAA↓Cr↑		R temp and front/R temp	B temp/B temp (L)	B temp (L temp)	L MCD	I
20	F/24/22	0	/NAA↓	PET: B temp↓ (R↓)	B temp and front/B temp and front	B temp/R temp	R temp	R HS + MCD	II
21	M/30/22	0	NAA↓Cho↑/NAA↓		B temp and L front/B temp	B temp/B temp	B temp (L temp)	L MCD	I
22	F/28/15	0	NAA↓/NAA↓	SPECT (ictal): L temp	B temp and R front/L temp	B temp/R temp	R temp and front	R HS + MCD	IV
23	M/13/8	0	NAA↓Cho↑		B temp and front/B temp	B temp/L temp	L temp	L HS + MCD	II
24	F/32/25	0	Cho↑/NAA↓		B temp and front/B temp (R)	B temp (R)/B temp and parietal (R)	R temp and parietal	R calcification	I

Notes: The metabolites with AI ≥0.12 are reported. NAA ↓ represents the AI of (NAA/[Cho + Cr]) or (NAA/Cr) or (NAA) ≥0.12.

Abbreviations: Pt, patient; MRI, magnetic resonance imaging; MRS, magnetic resonance spectroscopy; ipsilat, ipsilateral; contra, contralateral; EEG, electroencephalogram; PET, positron emission tomography; SPECT, single-photon emission computed tomography; IED, interictal epileptiform discharge; ictal, ictal activity; Engel, Engel classification; icEEG, intracranial EEG; TLE, temporal-lobe epilepsy; M, male; F, female; L, left; R, right; B, bilateral; HS, hippocampal sclerosis; TA, temporal abnormality; HA, hippocampal abnormality; 0, negative-MRI; NAA, N-acetyl aspartate; Cho, choline; Cr, creatine; temp, temporal lobe; front, frontal lobe; parietal, parietal lobe; MCD, malformation of cortical development; Na, not available due to non-surgery performed (for one patient); AI, asymmetry index.

Figure 1 ¹H-MR spectrum and MRI of individual patients. (A) ¹H-MR spectrum and MRI of patient 13 (31-year-old female; seizure history, 20 years; right [NAA/Cho + Cr] =0.48, left [NAA/Cho + Cr] =0.42; seizure focus in the left temporal region; left HS; surgical outcome, Engel class I). (B) ¹H-MR spectrum and MRI of patient 7 (38 year old male; seizure history, 28 years; right [NAA/(Cho + Cr)] =0.26, left [NAA/(Cho + Cr)] =0.35; seizure focus in the right temporal region; right HS; surgical outcome, Engel class II). (C) ¹H-MR spectrum and MRI of patient 20 (24-year-old female; seizure history, 22 years; right [NAA/Cho + Cr] =0.56, left [NAA/Cho + Cr] =0.48; seizure focus in the bilateral temporal regions; right HS; surgical outcome, Engel class II).

Abbreviations: R, right; L, left; ¹H-MR, proton magnetic resonance; MRI, magnetic resonance imaging; NAA, N-acetyl aspartate; Cho, choline; Cr, creatine; HS, hippocampal sclerosis; ppm, parts per million.

Figure 2 Surgical outcome of unilateral or bilateral MRI-positive or negative TLE (n=23).

Abbreviations: UnilT_MRI+, unilateral TLE with positive MRI (n=7); UnilT_MRI−, unilateral TLE with negative-MRI (n=4); BilT_MRI+, bilateral TLE with positive MRI (n=4); BilT_MRI−, bilateral TLE with negative-MRI (n=8); MRI, magnetic resonance imaging; TLE, temporal-lobe epilepsy.

Table 2 Spearman correlation between presurgical (and pathological) findings and surgical outcome

	Surgical outcome (Engel classification: I–IV)
	All patients (n=23)	Patients with positive MRI (n=11)	Patients with negative-MRI (n=12)
Age	−0.05	−0.30	−0.11
Sex	−0.11	−0.36	0.03
Duration of seizure	0.23	0.00	0.31
EEG_lat	−0.47 (P=0.025)a	−0.18	−0.67 (P=0.018)a
MRI_lat	−0.28	−0.62 (P=0.040)a	−0.21
MRS_lat	−0.20	−0.42	−0.14
icEEG_lat (n=12)	0.44 (P=0.036)a	0.39	0.56 (P=0.056)b
HS or notc	0.30	0.04	0.49

Notes: Due to the fuzziness and difficulty of combining the MRS data (NAA, Cr, Cho, etc), two sets of combination rules were applied. The value of correct MRS lateralization is the highest correlation coefficients (either positive or negative) of the two MRS_lat determined by the two MRS combination rules.

a Correlation coefficients were at two-tailed significance (P<0.05)

b correlation coefficients were at one-tailed significance (P<0.10)

c whether the patient has HS in the surgical site, which is determined by pathological findings.

Abbreviations: MRI, magnetic resonance imaging; EEG, electroencephalogram; EEG_lat, correct lateralization of EEG compared with the surgical site; MRI_lat, correct lateralization of MRI; MRS, magnetic resonance spectroscopy; MRS_ lat, correct lateralization of MRS; icEEG, intracranial EEG; icEEG_lat, correct lateralization of icEEG; HS, hippocampus sclerosis; NAA, N-acetyl aspartate; Cho, choline; Cr, creatine.