Dilemmas In Epilepsy Surgery
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Dilemmas in Temporal Lobe Epilepsy Surgery Dr Dilip S Kiyawat Epilepsy Guidance Clinic Jehangir Hospital Pune
Is he a surgical candidate • Intractability • szrs not controlled after adequate trial with 3 first line AEDs including polytherapy. • Determine how the szrs affect the pts QOL
• Concordance • EEG, MRI, Neuropsycology and seizure semiology
What age to select • • • •
Effects of repeated seizures on the brain It takes about 20 years to recognize Surgery as the last resort Addition of 4th AED helps only 5% of patients
Seizures Affect Other Areas of Brain
Surgical resection of these areas have not only abolished recurrent fits but also reverse the developmental delay and improve memory function and intelligence
Hippocampal Atrophy
Left Hippocampal Hyperintensity
Ganglioglioma
Gangliogioma
DNET
Nodular Neuronal Heteropia
What should be resected • Temporal neocortex: Recording with depth and surface electrodes show szrs of strict neocortical origin were rare. • The percentage of szrs is only 10% in the lesions confined to the surface of temporal lobe - AVM, dysplasias and tumours • Crucial role is played by A&H in TLE • Szr discharge start either in hippocampus > amygdala • Habitual szrs and aura can be reproduced by stimulation of A&H but rarely from the neocortical contacts
How to and How much to resect • Initial failures of temporal surgery was attributed to a too little resection of temporal lobe • Among the factors which influence the outcome in epilepsy surgery, the extent and modalities of resection are the most neglected and poorly studied ones. • In a series of 40 patients considered failures, a secondary hippocampectomy lead to szr free status in 63% of patients.
Extent and modality of resection Cortico-amygdalectomy (CA) • Resection of anterior 4.5 cm of temporal neocortex • Amygdala, together with parahippocampus adjacent to it • Results with this modality show higher failure rate • This operation is a safe compromise in dominant temporal lobe pathology who have failed the amytal test
Extent and modality of resection Cortico-amygdalohippocampectomy (CAH) Anterior temporal lobectomy anterior 4.5 cm of neocortex Amygdala Hippocampus Parahippocampal gyrus, fusiform gyrus and uncus
Extent and modality of resection Selective amygdalohippocampectomy (SAH)
• Trans sulcal - Approached through superior or inferior temporal sulcus • Trans sylvian fissure approach
Extent and modality of resection Lesionactomy and cortico-amygdalohippocampectomy Well circumscibed obvious lesions are excised together with gliotic area around it These are: benign tumours, cortical dysplasias or vascular malformations In vast majority of cases these lesions affect both neocortex and limbic structures and are treated by CAH and lesion excision
Extent and modality of resection Secondary Cortico- Amygdalohippocampectomy (SECAH) Recurrence of szrs has been noted where resection at the first operation was limited to neocortex or the hippocampus was not removed completely Recurrence of szrs 40 cases First operation
Recurrence of szrs
Only cortex
6
CA
13
CAH
21
Extent and modality of resection
Post operative szr outcome TLE Engle (1987) • Class l: Seizure free • Class ll: Rare szrs (3/yr) • Class lll: Worthwhile improvement (>90% improvement) • Class lV: No worthwhile improvement(<90% improvement) – lV a: significant improvement(60 to 90% reduction) – lV b: no change (less than 60% reduction) – lV c: worse
Outcome from various modalities (523) Outcome CAH (348)% l 67
CA (100)% 44
SAH (43)% 72
SECAH (56)% 55
20
12
17
31
Total
(87)
(56)
(89)
(86)
lV A
10
16
4
7
lV B
3
28
7
7
Total
(13)
(44)
(11)
(14)
ll & lll
Outcome and extent of hippocampal resection (523) Extent of resection
Outcome l-ll-lll Outcome lV A – % lV B %
No removal
56
44
1 – 1.5 cm
77
23
2 – 2.5 cm
86
14
3 – 3.5 cm
94
6
Dominant hemisphere pathology • Dominant hemisphere contains memory and speech • Dominant temporal lobe mainly contains memory • Non dominant temporal lobe contains constructional and structural capability
Poor Lateralization • Bilateral spikes/slow waves on EEG • Multiple video EEGs • Cortical recording from subdural grid or strip - interictal or ictal
case • • • • •
Male 19 yrs Fits since the first day of life Forceps delivery Eye deviation to Rt and lifting of Lt UL Opening the zip of his pant and passing urine in public and in the class • Frequency 7-8 /30 • Many trials of 2-3 AEDs failed
EEG
• Bilateral spikes • Video EEG: Also inconclusive
Bilateral Subdural Strip Recordings From Temporal Lobe
Is he a surgical candidate • Intractability • szrs not controlled after adequate trial with 3 first line AEDs including polytherapy. • Determine how the szrs affect the pts QOL
• Concordance • EEG, MRI, Neuropsycology and seizure semiology
What age to select • • • •
Effects of repeated seizures on the brain It takes about 20 years to recognize Surgery as the last resort Addition of 4th AED helps only 5% of patients
Seizures Affect Other Areas of Brain
Surgical resection of these areas have not only abolished recurrent fits but also reverse the developmental delay and improve memory function and intelligence
Hippocampal Atrophy
Left Hippocampal Hyperintensity
Ganglioglioma
Gangliogioma
DNET
Nodular Neuronal Heteropia
What should be resected • Temporal neocortex: Recording with depth and surface electrodes show szrs of strict neocortical origin were rare. • The percentage of szrs is only 10% in the lesions confined to the surface of temporal lobe - AVM, dysplasias and tumours • Crucial role is played by A&H in TLE • Szr discharge start either in hippocampus > amygdala • Habitual szrs and aura can be reproduced by stimulation of A&H but rarely from the neocortical contacts
How to and How much to resect • Initial failures of temporal surgery was attributed to a too little resection of temporal lobe • Among the factors which influence the outcome in epilepsy surgery, the extent and modalities of resection are the most neglected and poorly studied ones. • In a series of 40 patients considered failures, a secondary hippocampectomy lead to szr free status in 63% of patients.
Extent and modality of resection Cortico-amygdalectomy (CA) • Resection of anterior 4.5 cm of temporal neocortex • Amygdala, together with parahippocampus adjacent to it • Results with this modality show higher failure rate • This operation is a safe compromise in dominant temporal lobe pathology who have failed the amytal test
Extent and modality of resection Cortico-amygdalohippocampectomy (CAH) Anterior temporal lobectomy anterior 4.5 cm of neocortex Amygdala Hippocampus Parahippocampal gyrus, fusiform gyrus and uncus
Extent and modality of resection Selective amygdalohippocampectomy (SAH)
• Trans sulcal - Approached through superior or inferior temporal sulcus • Trans sylvian fissure approach
Extent and modality of resection Lesionactomy and cortico-amygdalohippocampectomy Well circumscibed obvious lesions are excised together with gliotic area around it These are: benign tumours, cortical dysplasias or vascular malformations In vast majority of cases these lesions affect both neocortex and limbic structures and are treated by CAH and lesion excision
Extent and modality of resection Secondary Cortico- Amygdalohippocampectomy (SECAH) Recurrence of szrs has been noted where resection at the first operation was limited to neocortex or the hippocampus was not removed completely Recurrence of szrs 40 cases First operation
Recurrence of szrs
Only cortex
6
CA
13
CAH
21
Extent and modality of resection
Post operative szr outcome TLE Engle (1987) • Class l: Seizure free • Class ll: Rare szrs (3/yr) • Class lll: Worthwhile improvement (>90% improvement) • Class lV: No worthwhile improvement(<90% improvement) – lV a: significant improvement(60 to 90% reduction) – lV b: no change (less than 60% reduction) – lV c: worse
Outcome from various modalities (523) Outcome CAH (348)% l 67
CA (100)% 44
SAH (43)% 72
SECAH (56)% 55
20
12
17
31
Total
(87)
(56)
(89)
(86)
lV A
10
16
4
7
lV B
3
28
7
7
Total
(13)
(44)
(11)
(14)
ll & lll
Outcome and extent of hippocampal resection (523) Extent of resection
Outcome l-ll-lll Outcome lV A – % lV B %
No removal
56
44
1 – 1.5 cm
77
23
2 – 2.5 cm
86
14
3 – 3.5 cm
94
6
Dominant hemisphere pathology • Dominant hemisphere contains memory and speech • Dominant temporal lobe mainly contains memory • Non dominant temporal lobe contains constructional and structural capability
Poor Lateralization • Bilateral spikes/slow waves on EEG • Multiple video EEGs • Cortical recording from subdural grid or strip - interictal or ictal
case • • • • •
Male 19 yrs Fits since the first day of life Forceps delivery Eye deviation to Rt and lifting of Lt UL Opening the zip of his pant and passing urine in public and in the class • Frequency 7-8 /30 • Many trials of 2-3 AEDs failed
EEG
• Bilateral spikes • Video EEG: Also inconclusive
Bilateral Subdural Strip Recordings From Temporal Lobe
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