Epilepsy Surgery for Tumors, Vascular
Malformations, Trauma and Cerebrovascular Disease
N. Eskandar, M.D.
MGH Epilepsy Center, Neurosurgical Service,
Massachusetts General Hospital
Harvard Medical School, Boston, Massachusetts
Address for Correspondence:
N. Eskandar, M.D.
Massachusetts General Hospital
15 Parkman St. ACC # 331
Boston, MA 02114
Patient Appointments: 617.724.6590
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The incidence of lesional epilepsy
has been estimated to represent between 20-30% of cases with intractable
seizures. (1) This incidence appears to be increasing due to the
widespread availability of advanced magnetic resonance imaging (MRI)
and its ability to identify subtle lesions that were previously
undetectable by computed tomography (CT). Many patients with a first
seizure will undergo a MRI scan and a "symptomatic lesion"
is discovered. In these cases, therapeutic strategies are typically
directed against the specific pathology and seizure control is rarely
a problem. In other cases, patients with seizure disorders of long
duration may eventually undergo neuro-imaging that detects a causative
lesion. This chapter will only discuss those cases of intractable
and recurrent seizures associated with such lesions.
The ability to identify a lesion as the cause of intractable epilepsy
generally signifies a more favorable surgical outcome, however two
important clinical issues remain. The first involves the natural
history of the underlying lesion itself and the risk that such pathology
imparts to the patient. The second involves the localization of
the presumed epileptic focus and its relationship to the lesion.
The surgical management of seizure patients with such intracranial
lesions can therefore consist of either simple excision of the structural
lesion itself (lesionectomy) or excision of the structural lesion
and surrounding epileptogenic cortex (lesionectomy plus corticectomy)
. The debate over whether one surgical approach has specific advantages
over the other remains unresolved and forms the basis of this chapter.
Clinical and Pathological Issues
Risk of Pathology
First and foremost, careful consideration
must be given to the natural history of the lesion identified and
the risk that such a lesion imparts to the health of the patient.
These issues especially predominate with arteriovenous malformations
and cavernomas which have a small (1-3%) but real risk of hemorrhage
each year. (2) This risk is cumulative over the life expectancy
of the patient and is therefore more important in younger individuals.
Most intrinsic brain tumors associated with intractable epilepsy
of long duration tend to be low grade and indolent (i.e. pilocytic
astrocytoma, DNET, ganglioglioma). Some other glial tumors such
as astrocytomas and oligodendrogliomas may also be associated with
a long history of recurrent seizures but can show progressive growth
or radiographic changes suggesting malignant transformation. These
tumors must be treated with appropriate neuro-oncological therapies.
In cases of post-traumatic epilepsy or seizures related to cerebral
infarction, the pathology is stable and non-progressive and in these
situations the intractability of the seizure disorder dominates.
Risk of Epilepsy
The risk of developing seizures from
a structural lesion depends on a wide variety of factors including
lesion type, lesion location and involvement of cortical gray matter.
In general, slow growing primary neoplasms of the brain tend to
be associated with the highest risk of seizures. Seizures are the
primary presenting symptom in 80-90% of patients with gangliogliomas.
(3,4) Dysembryoplastic neuro-epithelial tumors (DNET's) and pilocytic
astrocytomas are also associated with a high incidence of intractable
epilepsy. (5) More aggressive, rapidly growing tumors such as glioblastoma
multiforme (GBM) and cerebral metastases are associated with a lower
risk of seizures in the range of 20 to 30%. (6) Oligodendrogliomas
which may be either very slow growing and indolent or have more
anaplastic features are classically associated with epilepsy in
50-75% of cases with a lower incidence in the more aggressive tumors
and older patients. (7) Supratentorial meningiomas are associated
with about a 50% risk of seizures although they tend to be less
refractory to medical therapy. (8)
Arteriovenous malformations (AVMs)
have also been associated with a risk of seizures in the 30 - 35%
range. (9) However, even patients harboring an AVM that has never
ruptured have a 1.0 - 2.3% risk of hemorrhage per year and this
must also be taken into consideration. (2) Cavernous angiomas present
with seizures in 39 - 55% of cases and are often refractory to medical
management. (10,11) The risk of seizures from venous angiomas is
small and estimated to be about 5%. (12)
Cerebral vascular disease resulting
in stroke or intracranial hemorrhage represents an important cause
of seizures especially in the elderly. Cerebral infarction in the
older population (> 50 years of age) has been found to be the
cause of new-onset seizures in approximately 20% of cases. (13)
Seizures may complicate subarachnoid hemorrhage in 10 - 20% of cases
and are probably more common in patients that harbor a peri-sylvian
or temporal lobe hematoma. (14) Intracerebral hematomas, especially
of the lobar type, are associated with seizures in about 28% of
cases whereas deep basal ganglia hematomas have a much lower incidence.
Craniocerebral trauma has also been
associated with approximately a 20% risk of post-traumatic epilepsy.
(16) Diffuse closed head injury has a lower incidence than compound
fractures or penetrating cerebral injury or closed head injury associated
with intracranial hematomas.
Mechanisms of Epilepsy
Although it is clear that seizures
can be associated with structural cerebral lesions it is not known
by what mechanisms these seizures occur. It is generally acknowledged
that the seizures do not arise from the lesion itself but rather
from the irritated cortex immediately adjacent to the lesion. On
occasion, seizures may arise from within the border zone of an infiltrative
lesion such as an oligodendroglioma or astrocytoma.
Exact mechanisms of epileptogenicity are unknown although a number
of electrophysiologic and pathophysiologic theories have been proposed.
These include changes in altered neurotransmitter levels (GABA and
somatostatin), free radical formation and altered second messenger
physiology. (17) Morphological changes have also been identified
such as alterations in vascular supply, neuronal cell loss, glial
proliferation and subtle subcortical disconnections. (18) In the
case of AVMs and cavernous angiomas and intracerebral hemorrhage,
it is suspected that the breakdown products of the blood deposit
ferric ions into the surrounding cortex which is a known epileptogenic
In order for lesions to cause seizures,
however, they generally must involve gray matter or the cortical
mantel. In addition, specific areas of the cortex are associated
with higher risks of seizures. Lesions in the Rolandic or peri-Rolandic
cortex as well as the limbic areas tend to be the most epileptogenic.
Lesions involving the temporal lobe are also associated with a higher
incidence of seizures as compared to extra-temporal locations. (19)
Lesion size may also represent a factor in epileptogenicity but
there may be a variety of unknown mechanisms for the different pathologies.
A final issue that must be considered
is the possibility that the lesion identified on imaging is causing
epileptiform abnormalities at a distant site. For example, a lesion
in the temporal lobe may be associated with atrophy and gliosis
in the hippocampus. Whether this represents true dual pathology
or the consequence of repeated epileptogenic discharges is unclear.
In rare instances, a structural lesion may be an incidental finding
and not play any role in seizure onset. The implications for presurgical
evaluation and subsequent surgical decision-making are obvious.
Overall, however, the general underlying assumption is that the
morphologic or physiologic changes in the cortex that result in
the epileptic condition are somehow caused by the structural lesion
and its relationship with the surrounding cortex.
Although the approach to patients with
lesional epilepsy is often simplified by the neuro-imaging data,
the principles of sound presurgical evaluation should not be ignored.
A detailed description of the clinical semiology of the habitual
events is important to determine if the seizures are consistent
with the lesion location or whether the lesion may be an incidental
finding. At times, the clinical features of the seizure are so distinct
that it may clearly localize the seizure onset to the identified
lesion. This would be the case in a patient having simple partial
seizures with episodes of speech arrest and a cavernous angioma
in the dominate frontal operculum. (Figure 1) Similarly, the clinical/radiological
correlation is extremely compelling in a patient with focal motor
seizures of the right hand and a lesion involving the left Rolandic
cortex. In both of these situations it might be reasonable to consider
lesionectomy as an appropriate intervention because of the likelihood
of successful control of the seizures.
Advanced neuro-imaging remains one
of the most important aspects in the presurgical evaluation by providing
information about the exact location and extent of the lesion. Particular
MR imaging characteristics may help identify the underlying pathology
and can demonstrate associated features of mass effect, focal atrophy
or calvarial molding. On occasion, it can identify obvious dual
pathology such as distinct hippocampal atrophy associated with a
neocortical temporal lesion. Recent advances in functional MRI (fMRI)
can also provide important information regarding the localization
of eloquent cortex adjacent to lesions or planned resection lines.
In the future, MR spectroscopy may be able to provide distinct neurochemical
information on mass lesions that might correlate with specific histopathology.
Computerized tomography (CT ) scans can be helpful in determining
the presence or absence of fine calcifications. Positron emission
tomography (PET) scanning to demonstrate regional hypometabolism
is generally not needed for patients with lesional epilepsy. The
presence of the lesion can often make accurate interpretation of
the PET scan difficult. Similarly, single photon emission computed
tomography (SPECT) provides little useful information in the presence
of a mass lesion. Cerebral angiography is only necessary for arteriovenous
Ictal video/EEG recordings are probably necessary in most cases
of lesional epilepsy to confirm that the seizure onset is indeed
localized to the area of the lesion. Demonstrating electrographically
that the seizure onset is consistent with the lesion location confirms
the role of the lesion in the patients seizure disorder and imparts
an excellent prognosis in terms of surgical outcome. Consistent
and convincing inter-ictal EEG evidence of epileptiform activity
originating in the area of the lesion however may be adequate in
some cases. For example, in a patient with intractable complex partial
seizures and a low grade glioma in the mesial temporal lobe, consistent
interictal epileptiform activity on scalp EEG from the same temporal
lobe would make the patient a reasonable candidate for surgery even
without ictal EEG recordings. (Figure 2) In some instances, ictal
EEG data may be falsely localizing and geographically distant from
the lesion. These patients can still be considered for surgery but
may need more extensive presurgical evaluation.
Invasive intracranial monitoring has frequently been used to evaluate
patients with lesional epilepsy. Generally, large subdural grid
arrays are placed over the lesion and surrounding cortex. Ictal
EEG recordings from these arrays can often define the exact region
of seizure onset in relation to the lesion and reveal pathways of
seizure propagation. This information is then used to devise a resection
strategy that encompasses both resection of the lesion and the surrounding
cortex. Intracranial grids are also useful for mapping cortical
function extraoperatively prior to excision of the lesion and surrounding
cortex. This is especially true in the pediatric population. Subdural
strip electrodes and intracerebral depth electrodes can also be
useful in localizing seizure onset but the intracranial investigation
strategy must be carefully individualized. Occasionally even intracranial
EEG investigation may be misleading if an inadequate number of electrodes
are used. The mortality and morbidity associated with subdural grid
electrodes has been estimated at @ 2 - 4% and therefore the use
of invasive intracranial monitoring must be balanced by the expense
and risk of these investigations. (20)
The presurgical evaluation of patients
with intractable epilepsy generally requires detailed neuropsychological
testing and assessment of a variety of psychosocial factors. While
extremely important in certain cases as a baseline study, and as
a predictor of the risk of resective surgery, it is not mandatory
in patients undergoing limited lesionectomy.
The primary goal of any surgical treatment
for intractable epilepsy is to abolish the seizures and avoid any
neurologic deficits associated with the resection. A secondary goal,
in cases of tumors and vascular malformations is to entirely remove
the lesion for a maximal therapeutic benefit. The major controversy
in lesional epilepsy surgery is whether lesionectomy alone is adequate
to achieve these goals or whether lesionectomy plus corticectomy
provides better seizure control.
For the purposes of this chapter, a
"lesionectomy" refers to the removal of a structural lesion
using conventional neurosurgical operative techniques. This may
entail resection of some overlying cortex in the approach to lesions
but does not specifically or intentionally identify and resect surrounding
epileptogenic cortex. "Lesionectomy plus corticectomy"
refers to the surgical removal of the structural lesion as well
as the identification and resection of surrounding epileptogenic
cortex to improve seizure control. This can be accomplished using
either acute intraoperative electrocorticography (EcoG) or with
chronic extraoperative intracranial recordings.
The long-standing debate over lesionectomy
versus lesionectomy plus corticectomy began with the observation
that many patients do become seizure free or have a dramatic reduction
in seizures after simple excision of a structural cortical lesion.
The patient may be cured of seizures even though scalp EEG abnormalities
remain. Falconer described several patients with structural lesions
and EEG foci distinct from the lesion who underwent lesionectomy
but no attempt at resection of the EEG focus. Many of these patients
not only had a dramatic reduction in the seizure frequency but also
had disappearance of the scalp EEG focus. (21) The disappearance
of this distinct EEG focus often took many months suggesting a "running
down" phenomenon. In other cases, the scalp EEG abnormalities
remained but no longer resulted in clinical seizures. These observations
suggest that a structural lesion does not necessarily result in
permanent epileptogenic changes in the surrounding cortex and that
lesionectomy alone may be able to reverse the epileptic condition
in certain cases.
On the other hand, there are cases
where lesionectomy alone does not relieve the patient of their seizures.
This may be due to the presence of independent epileptogenic cortex,
inadequate resection of the original lesion, or postoperative scar
formation. The epileptogenic cortex may be geographically distant
from the structural lesion and can become functionally independent
despite lesionectomy. (22) This concept of "kindling"
is well described in animal models but less well understood in the
human condition. In these cases, resection of the lesion alone without
removal of the functionally independent epileptogenic cortex would
result in a surgical failure. In order to accurately identify these
areas however requires invasive cortical monitoring, the results
of which would guide a tailored resection of the lesion and surrounding
cortex. The possibility of independent epileptic foci is less likely
with smaller well-circumscribed lesions and more likely with the
diffuse cerebral pathology that can result from trauma or cerebrovascular
One alternative surgical approach is
to suggest that patients with lesional epilepsy should undergo resection
of the structural lesion after appropriate non-invasive presurgical
evaluation. In many instances, especially those patients with cavernous
angiomas or low grade gliomas, 70 to 80% of patients will remain
seizure free after surgery. If the seizures persist after lesionectomy,
then a more detailed and comprehensive evaluation could be undertaken
with subdural grids, strips or intracerebral electrodes. This approach
would minimize the expense and risk of invasive intracranial monitoring
in all patients and seems a cost-efficient and effective compromise.
There are several studies in the literature
that have attempted to compare lesionectomy to lesionectomy plus
surrounding epileptic cortex. The earliest study was a retrospective
review by Gonzales and Elvidge at the Montreal Neurological Institute
of 100 patients with low grade astrocytomas and intractable seizures.
(23) Fifty two patients underwent lesionectomy and 48 had lesionectomy
plus resection of surrounding cortex guided by intraoperative EcoG.
Of the 53 remaining patients available for follow up at 5 years,
9 of 25 (36%) of lesionectomy candidates continued to have seizures
compared to 6 of 28 (21%) who had undergone lesionectomy plus. Goldring
et al compared the results of lesionectomy versus lesionectomy plus
in patients with a variety of structural lesions and concluded that
simple excision of the lesion was favorable and provided better
seizure control. (24,25) Spencer et al reported their experience
in 27 patients with lesions primarily involving the temporal lobe
and observed a dramatic advantage of lesionectomy plus tailored
cortical resection over simple excision. (26) All of these studies
were flawed by their non-randomized nature and a retrospective selection
Modern series of lesionectomy alone
have demonstrated acceptable seizure free rates after surgery. Cascino
et al reported their experience from the Mayo Clinic of stereotactic
lesionectomy without cortical resection and found that this approach
provided satisfactory outcomes in over 80% of patients although
significantly fewer were completely seizure free. (27) The majority
of these cases were extra-temporal and additional cortical resection
was limited by the location of the lesions in eloquent cortex. The
same group subsequently reported their experience in 51 patients
with low-grade gliomas using either lesionectomy (n=17) or lesionectomy
plus corticectomy (n=34) and noted 34/51 of their patients were
seizure free at > 2 years follow-up. (28) Patients in both groups
did equally well but patients with complete tumor resection had
the best outcome.
In a large series of patients harboring
tumors in the temporal lobe, complete lesion resection was associated
with a 81% seizure free rate with a failure of seizure control associated
with incomplete resection of the lesion. (29) Resection was not
guided by EcoG and seizure free rates were not related to extent
of mesial resection.
In contrast, other groups have found
that simple excision of lesions involving the temporal lobe is often
not successful in relieving seizures. Lombardi et al reported their
experience in 15 cases of temporal lobe lesion and in 7 case of
extra-temporal lesions. (30) In the 8 cases in the temporal lobe
that did not involve the amygdala -hippocampus, lesionectomy alone
yielded a Engel Class I in 4 cases but no improvement in the remaining
4. These 4 failures were reoperated upon with resection of the amygdalo-hippocampus
with good results. Of the 7 extratemporal cases, lesionectomy alone
was completely successful (Engel Class I) in 5, partially successful
(Engel Class II) in 1 and unsuccessful (Engel Class IV) in 1. The
last patient underwent subsequent invasive intracranial monitoring
and frontal lobectomy to become seizure free at two years. An alternative
approach to tumors in the temporal region is to perform en-bloc
resections of the temporal lobe along with the tumor. In 31 patients
with low-grade gliomas (predominately DNETs), this technique made
81% of patients seizure free. (31)
In 47 patients with structural lesions
evaluated at the Cleveland Clinic, the presurgical evaluation involved
both non-invasive EEG recordings and invasive EEG recordings using
implanted subdural grids. (32) These grids were placed over the
lesion and ictal recordings obtained. The epileptic zone involved
the lesion only in 11/47 cases and extended beyond the lesion in
18/47 cases. In the remaining 18 cases, remote and noncontiguous
epileptic zones were discovered. Postoperative control of seizures
was obtained in 17 of 18 patients who underwent complete lesion
excision regardless of the extent of seizure focus excision. Postoperative
control of seizures was obtained in 5 of 6 patients with incomplete
lesion excision but complete seizure focus excisions but in only
12 of 23 with incomplete lesion excision and incomplete focus excision.
The most important variable predicting success of the surgical intervention
was the completeness of lesion resection.
In a large series of 146 patients with
brain tumors and medically intractable epilepsy, lesionectomy plus
corticectomy yielded an Engel Class I outcome in 82% of patients
at 6 months. (33) Most lesions were located in the temporal lobe
and most were indolent low grade primary brain tumors ( gangliogliomas,
pilocytic astrocytomas, DNET). This experience reinforces the importance
of complete lesion resection in seizure control.
The experience with lesionectomy for
cavernous angiomas is similar to that with low grade tumors. Lesionectomy
alone can lead to seizure free rates in 70 - 90 % of patients. (34)
Lesionectomy plus more extensive cortical resection may be necessary
in case where the is poor concordance between the location of the
lesion and the localizing data. Lesionectomy plus guided by intraoperative
EcoG also provides seizure free rates of 80 - 90 %. It is generally
agreed upon that the hemosiderin ring around the cavernoma must
also be removed in order to achieve complete relief of seizures
but several recent studies have suggested that this is unnecessary.
Seizures may occur secondary to a cortical
AVM whether the lesion has produced a clinical SAH or not. Seizures
are the initial manifestation in about a third of patients but are
generally intractable and incapacitating in only 10-15% of patients.
Larger AVMs tend to be associated with seizures whereas smaller
AVMs tend to be associated with SAH. Surgery for those patients
with intractable epilepsy can achieve excellent results in @ 70%
of patients. Outcomes appear to be better in patients who are slightly
older at presentation (>30 years of age) and who have had seizures
for less than one year.(36)
A recent meta-analysis of all studies
involving lesional epilepsy reported in the literature using inappropriate
outcome criteria (study size > 5 patients, postoperative follow
up of > 2 years, and Engel Classification of seizure outcome)
demonstrated a clear advantage of lesionectomy plus corticectomy
over lesionectomy alone.(37) The analysis revealed that while both
surgical approaches clearly reduce seizures in many patients, a
patient who had undergone lesionectomy alone was almost twice as
likely to continue to experience seizures after surgery as a patient
who had undergone lesionectomy plus surrounding cortex for the same
pathological lesion. The problem with this type of analysis is that
surgical techniques differ from center to center. Some centers perform
tailored resections based upon prolonged intraoperative EcoG while
others use chronically implanted electrodes. The variations in presurgical
evaluation and surgical technique make direct comparisons of outcome
difficult. Nevertheless, it does appear that lesionectomy plus resection
of surrounding epileptic cortex can provide improved seizure control
in the majority of cases of lesional epilepsy.
It is clear that lesionectomy can provide
excellent seizure control in many patients. This is especially true
for those patients with lesions who have infrequent or rare seizures
of less than a years duration. Even patients with a long history
of intractable epilepsy may be relieved of their seizures by simple
resection of the lesion. However, in order to select those patients
that might benefit from lesionectomy and those that might need lesionectomy
plus corticectomy, the presurgical evaluation must be individualized.
In certain cases, it may be adequate
to select patients for surgery simply on the basis of MRI identification
of the lesion and the clinical semiology of the seizures. If the
clinical features of the patients seizures are entirely consistent
with the location of the lesion, then lesionectomy alone has a reasonable
chance of success. This is especially true for lesions that are
small and are highly epileptogenic such as cavernous angiomas and
low grade gliomas. In these situations, resection of the lesion
is generally associated with a good prognosis in terms of seizure
control. If seizures are not well-controlled, then a more rigorous
and intensive presurgical investigation could be carried out.
In most cases, however, inter-ictal
and ictal EEG recordings are necessary to better define the zone
of seizure onset in relationship to the lesion. This is especially
true in patients with complex partial seizures in whom the clinical
semiology of the seizure often does not provide convincing localizing
information. Inter-ictal EEG recordings alone may be sufficient
in cases where there is good correlation between the lesion location
and inter-ictal EEG evidence of epileptogenicity. In most cases
however, the principles of multidisciplinary presurgical evaluation
are followed by attempting to localize the seizure onset to the
site of the lesion. Ictal-EEG recordings that demonstrate that the
seizures arise from the same region as the lesion identified on
neuroimaging, implies that resection of the lesion will impart substantial
therapeutic benefit. Invasive EEG recordings may be required when
a lesion is identified but seems anatomically distinct from the
area of seizure onset. Intracranial recordings with subdural strip
or intracerebral electrodes may demonstrate that the lesion is an
incidental finding and unrelated to seizure onset or that seizures
actually do arise in close proximity to the lesion but were not
detectable on scalp electrodes. Intracranial EEG investigation may
also be necessary in cases of diffuse lesions involving large areas
of cortex in order to identify the cortical regions adjacent to
the lesion where seizures arise. This is particularly true when
investigating lesions associated with ischemic cerebrovascular disease
One issue that is extremely important
in terms of a favorable surgical outcome is the completeness of
resection of the lesion. Surgical approaches that do not entirely
remove the offending lesion are generally less successful. In certain
situations, the location of the lesion and its involvement of essential
cortex prevents the complete removal of the lesion because of the
risk of irreversible neurological deficit.
Specific pathological issues are of great importance in that certain
lesions are associated with a high incidence of surgical success
after lesionectomy. These include cavernous angioma which is associated
with a greater than 80% seizure free rate. The low grade gliomas
including pilocytic astrocytoma, ganglioglioma and DNET are also
associated with an extremely high success rate after lesionectomy
alone. In these instances, lesionectomy is an appropriate first
Overall, it appears that the surgical
results following lesionectomy plus corticectomy are superior to
lesionectomy alone. This may be due to a variety of factors including
patient selection, differences in presurgical evaluation, center
experience and surgical technique. In general, a tailored resection
guided by detailed presurgical evaluation, intracranial or intraoperative
EEG recordings is more likely to remove the causative lesion as
well as surrounding epileptogenic cortex. This approach is more
likely to remove not only the regions of seizure onset but also
the areas involved in seizure propagation and areas of secondary
epileptogenesis. In the temporal lobe, lesionectomy alone is often
not successful because there are additional regions in the involved
temporal lobe that are fundamentally involved in seizure onset and
propagation. Lesionectomy alone is rarely successful in the temporal
lobe where dual pathology is often present and pathways of propagation
often have kindled nearby areas.
There is no question that modern neuroimaging
has detected an increasing number of lesions. The presence of a
lesion certainly increases the localization accuracy of seizure
onset. The presurgical evaluation and treatment however must be
individualized in all circumstances. Lesionectomy is often successful
in certain circumstances including cavernous angioma and low grade
gliomas. If lesionectomy is unsuccessful in these patients, a more
detailed and comprehensive evaluation is often necessary. Lesionectomy
plus corticectomy is generally more successful than lesionectomy
alone in most patients with lesional epilepsy. Overall, the prognosis
for seizure control is excellent in patients undergoing surgical
treatment of seizures related to tumors, vascular malformations
and cerebral vascular disease.
Figure 1 Axial T1-weighted MRIwith
gadolinium demonstrates a heterogenous lesion in the left temporal
lobe consistent with a cavernous angioma. Note the heterogenous
signal of the lesion with a surrounding ring of low signal likely
representing hemosiderin. This young women had intractable simple
and complex partial seizures characterized by speech arrest which
were completely cured by lesionectomy despite the fact that EEG
recordings were non-localizing.
Figure 2 Coronal T1-weighted MRI demonstrates
a low grade cystic tumor in the left mesial temporal lobe. Interictal
EEG recordings demonstrated frequent left temporal spike discharges
and the patient underwent lesionectomy plus anterior temporal corticectomy
and has been seizure free for over 5 years. Pathology demonstrated
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