Seizure 1995; 4:61-65

CASE REPORT

Seizures and 'disappearing' brain lesions
T. HEMANTH RAO, RICHARD B. LIBMAN & MAHENDRA PATEL*
Departments of Neurology and *Radiology, Long Island Jewish Medical Center, The Long Island Campus for The
Albert Einstein College of Medicine, New Hyde Park, New York, USA.
Address correspondence to: Richard B. Libman, MD, The Department of Neurology, Long Island Jewish Medical Center, New
Hyde Park, NY 11042, USA.

Background--Patients with seizures may have abnormal brain imaging. Lesions demonstrated on computerized tomography or magnetic resonance imaging often suggest the underlying cause of the seizures, and may
prompt an invasive investigation for diagnosis and treatment. In an increasingly recognized subset of patients
however, the imaged lesions spontaneously resolve. While poorly understood, these 'disappearing' lesions may
in fact be the consequence of seizures, rather than the cause. Two patients with 'disappearing' lesions are
presented: the first patient had a proven cause, the second a probable one.
Case 1. A patient with new onset seizures had an abnormal MRI. An angiogram confirmed thrombosis of the
straight sinus. On follow-up, she was doing well; repeat imaging was normal with resolution of the lesion.
Case 2. A patient with a long seizure history had been well controlled on medications, and had no change in
frequency of her seizures. She was found to have a left homonymous hemianopsia. MRI revealed a right
parieto-occipital lesion. The patient refused further work-up and was lost to follow-up. She returned almost a
year later; repeat imaging was normal.
Conclusion--Patients with seizures and abnormal imaging suggestive of structural lesions may occasionally
have lesions that resolve spontaneously. While some diagnoses remain elusive, an important consideration to
exclude in these patients is venous thrombosis.

Key words: seizures; epilepsy; cysticercosis; venous thrombosis.

In patients with seizures, focal abnormalities
on computerized tomography (CT) or magnetic
resonance imaging (MRI) prompt f u r t h e r
investigation to determine w h e t h e r or not
these lesions are causative. In most cases,
these lesions persist unless specific therapeutic
interventions are undertaken. Rarely, lesions
disappear spontaneously and are believed to be
the consequence of seizures. They m ay repr es en t metabolic disturbances t h a t occur
around a seizure focus 1-3. Disappearing lesions
m a y have other aetiologies, however 4-8. We
report two patients with seizures and lesions
on MRI t h a t spontaneously disappeared, but
which were apparently not caused by seizures.
Recognition of this poorly understood entity
m a y change the approach to some seizure
patients with abnormal imaging.
1059-1311/95/010061 +05 $08.00•0

PATIENT 1
A 43-year-old woman without a significant
past medical history was referred to our institution after a first generalized seizure. She was
reportedly in her usual state of good health the
day of admission, when she suddenly lost consciousness. H er family noted t h a t her eyes
rolled upward and she developed shaking of all
her extremities, which lasted between 1 and 2
minutes. This was associated with u r i n a r y
incontinence, but t here was no tongue biting,
faecal incontinence or any other associated
features. She denied similar episodes in the
past. She was t a k e n to her family doctor who
obtained an MRI scan and referred her to our
institution. In the emergency room she was
without complaints. On general examination
© 1995 British Epilepsy Association

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T.H. Rao et aL

(b)
!.

Fig. 1 : (a) Initial T2-weighted MRI showing abnormal signal in bilateral occipital regions. (b) Cerebral angiogram showing straight
sinus thrombosis (L-enlarged vein of Labbe; small arrows--presumed location of thrombosed straight sinus; large arrow-thrombosis extending to torcular Herophili). (c) MRI 9 weeks later.

she was afebrile, normotensive, and her neck
was supple without adenopathy. The rest of her
general physical exam was normal. Her neurological examination was normal.
Routine laboratory investigations including
a complete blood count, chemistry panel, liver
function tests, kidney function tests and coagulation profile were within normal limits. Her

T-2 weighted MRI scan revealed two areas of
increased signal in both parieto-occipital
areas, confined mostly to white matter (Fig.
l(a)). A cerebral arteriogram was done because
of the peculiar distribution of the lesions,
which confirmed a straight sinus thrombosis
(Fig. l(b)).
The patient was started on carbamazepine

Disappearing lesions

and her hospital course was uneventful. On
follow-up she remained asymptomatic. A
repeat MRI scan obtained 8-9 weeks later was
normal (Fig. l(c)).

63

therapeutic procedures during the previous
year.

DISCUSSION
PATIENT 2

A 54-year-old woman had a long history of
post-traumatic seizures, believed secondary to
have been beaten with a baseball bat as a
teenager. She was seen in clinic for routine
follow-up. She reported an average seizure frequency of once or twice per year. Her seizures
typically began with right-sided clonic jerks
followed by secondary generalization. Her last
seizure had been 12 days prior to evaluation,
and had been relatively brief according to her
family (less than 1 minute). This seizure was
atypical because it was generalized from the
outset without right-sided clonic movements.
There had been no change in seizure type or
frequency over the previous few years. She had
been compliant with her anticonvulsant medication (phenytoin). There was no history of
foreign travel, drug abuse, or recurrent
trauma. Imaging studies in the past, including
a CT scan done within the previous month
were negative for acute structural pathology,
showing only an area of encephalomalacia in
the left parietal region, consistent with her
history of trauma. The EEG showed only left
fronto-parietal slowing; no focal spikes had
ever been documented.
The general physical examination was
normal without adenopathy or meningismus.
Neurological examination was normal except
for a left homonymous hemianopsia which had
not been present on her examination 4 months
previously. She underwent an MRI which, in
addition to the previously documented area of
encephalomalacia, revealed an area of increased signal in the right temporo-occipital
region on proton density images, apparently
confined to the white m a t t e r and without mass
effect (Fig. 2(a)). A neoplastic or infectious
lesion was suspected, but the patient refused
further work-up and was lost to follow-up. One
y e a r later, she was re-evaluated. She remained
asymptomatic, and the homonymous hemianopsia was no longer present. A repeat MRI
showed virtually complete resolution of the
abnormal signal (Fig. 2(b)). EEG was
unchanged from her previous studies. She
denied taking any medication other than her
phenytoin or undergoing any diagnostic or

Transient CT lesions that correlate with an
ictal focus are thought to be secondary to a
metabolic disturbance around the focus, resulting in abnormal vascular permeability and cerebral edema 1-3. These CT lesions have been
reported with either repeated focal seizures 1'2
or focal status epilepticus 3. The location of the
imaged lesion generally corresponds to the presumed seizure focus 1, which was not the case in
our patients. These lesions disappear when the
seizures are controlled with medications. The
above mechanism of abnormal vascular permeability is also the most likely explanation
for the reversible lesions seen in eclampsia 5'6.
Our first patient had a documented straight
sinus thrombosis as the presumed cause of her
seizures and imaged lesions on MRI. These
lesions were probably due to venous ischemia
which did not progress to infarction because of
rapid recanalization. Our second patient had a
similar lesion on MRI scan, and she did not
have prolonged or repeated focal seizures.
Therefore, the postulate that seizures were the
cause
of our patient's lesion, while possible,
seems unlikely. Another possible cause of disapearing lesions is thought to be cryptic angiomas that rupture. The signal characteristics
of our patient's lesion were not suggestive of
haemorrhage.
Self-limited focal encephalitis is a possible
diagnosis in our second patient. Focal encephalitis secondary to a bacterial pathogen such as
tuberculosis does not resolve without specific
therapy, making that diagnosis highly improbable. The bulk of patients reported with
disappearing lesions have been from the
Indian subcontinent and Central or South
America where cysticercosis is endemic. The
reported lesions have typically been without
mass effect2. A certain percentage of patients
with cysticercosis during the acute encephalitic phase do spontaneously resolve 4 and
spontaneous radiographic disappearance of
cerebral cysticercosis has also been reported 7.
To attribute our patient's lesion to cysticercosis
is difficult because she was not from an endemic area, and was without a history of travel
to an endemic area, although sporadic cases of
cerebral cysticercosis acquired in the United
States have been documenteds'9. In our second

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(a)

(b)

Fig. 2: (a) Initial proton density MRI showing abnormal signal in right parieto-occipital region. (b) MRI 1 year later.

T.H. Rao et al.

Disappearing lesions

p a t i e n t t h e d i f f e r e n t i a l diagnosis m a y include
a s e l f - l i m i t e d focal e n c e p h a l i t i s p e r h a p s due to
cysticercosis, possibly a n u n i d e n t i f i e d v i r a l
infection, b u t m o r e likely u n s u s p e c t e d (and
u n d o c u m e n t e d ) v e n o u s ischemia.
I n conclusion, p a t i e n t s w i t h seizures m a y
h a v e a b n o r m a l i m a g i n g s u g g e s t i v e of struct u r a l lesions, w i t h p r e s u m e d v a s o g e n i c o e d e m a
b u t w i t h o u t significant m a s s effect. A s u b s e t of
t h e s e p a t i e n t s will h a v e ' d i s a p p e a r i n g ' lesions.
T h e t e r m ' d i s a p p e a r i n g ' lesions p r o b a b l y
e n c o m p a s s e s a h e t e r o g e n e o u s g r o u p of disorders. To o u r knowledge, this is t h e first reported association between 'disappearing'
lesions a n d v e n o u s t h r o m b o s i s . V e n o u s t h r o m bosis is a n i m p o r t a n t diagnosis to exclude as
specific t h e r a p y , i.e. a n t i c o a g u l a t i o n , could be
i n i t i a t e d a n d m i g h t p r e v e n t clinical deterior a t i o n or i m p r o v e t h e c h a n c e s of good recove r y 1°.

ACKNOWLEDGEMENT
We t h a n k R o n a l d K a n n e r , MD, for his helpful
r e v i e w of a n e a r l i e r v e r s i o n of t h e m a n u s c r i p t .

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Appearing and disappearing CT scan abnormalities

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