Clinical Neurology and Neurosurgery 113 (2011) 925–927

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Clinical Neurology and Neurosurgery
journal homepage: www.elsevier.com/locate/clineuro

Case report

Perfusion computer tomography helps to differentiate seizure and stroke in
acute setting
Chuh-Hyoun Lie a , Mirko Seifert b , Jörg Poggenborg b , Gereon R. Fink a,c , Lothar Burghaus a,∗
a
b
c

Department of Neurology, University Hospital of Cologne, 50924 Cologne, Germany
Department of Radiology, University Hospital of Cologne, Cologne, Germany
Institute of Neuroscience and Medicine, Cognitive Neurology Section, Research Centre Juelich, Juelich, Germany

a r t i c l e

i n f o

Article history:
Received 21 July 2010
Received in revised form 5 June 2011
Accepted 25 June 2011
Available online 23 July 2011
Keywords:
Perfusion CT
Nonconvulsive status epilepticus
Stroke

2. Case report
2.1. Medical history
A 68-year-old patient was admitted to the hospital with aphasia
and right-sided hemiparesis. The patient had a history of left occipital meningeoma resection 3 years ago, causing a right homonymous
hemianopsia. Slight secondary deterioration in the later course, due
to recurrent meningeoma, resulted in a radiation therapy 3 months
ago. No other neurological deficits, apart from hemianopsia, were
observed either post-surgery or post-radiation.
2.2. Diagnostic issues

1. Introduction
The acute onset of neurological symptoms raises the suspicion of stroke, but a subgroup of patients suffers conditions that
mimic stroke. Seizures are a common feature of stroke-mimicking
symptoms and include postictal state with Todd’s paralysis or
inhibitory seizures. In an acute setting, imaging is an important part
of the diagnostic work-up in stroke patients, because thrombolytic
therapy relies on the exclusion of hemorrhage. Non-enhanced computer tomography (CT) is the most common imaging technique in
acute stroke, and additional scans (CT angiography [CT-A], perfusion CT [P-CT]) help to improve the diagnostic value. The wealth of
data regarding the use of P-CT in acute stroke is contrasted by the
absence of data regarding the diagnostic value of P-CT in epilepsy.
We report the case of a patient with an acute onset of aphasia and
right-sided hemiparesis, in which a P-CT scan revealed regional
hyperperfusion and further diagnostic supported an epileptic origin.

Initially, an acute stroke was assumed and a CT scan was performed in order to assess whether thrombolytic therapy could be
administered. The nonenhanced CT scan showed a left occipital
post-operative defect, while no signs of an acute ischemia were
found. CT-A and P-CT were performed additionally.
2.3. Methods
Using a Philips multislice scanner (Brilliance G), P-CT comprised
of two series during intravenous administration of iodinated contrast material. Region of interest analysis was applied, thereby
allowing for a comparison of areas between hemispheres with
regard to cerebral blood flow (CBF), cerebral blood volume (CBV)
and mean transit time (MTT).
2.4. Results
P-CT revealed regional hyperperfusion, with elevated CBF and
CBV in the left parietal lobe, while MTT was not significantly altered
when comparing both hemispheres (see Fig. 1, see Table 1). CT-A
did not show significant differences in the diameter between the
right and left posterior cerebral artery.
2.5. Further course and therapy

∗ Corresponding author. Tel.: +49 221 478 4014; fax: +49 221 478 88819.
E-mail address: lothar.burghaus@uk-koeln.de (L. Burghaus).
0303-8467/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.clineuro.2011.06.009

Later on, the patient presented clonic movements of the
right leg, which could be prevented by intravenous application

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C.-H. Lie et al. / Clinical Neurology and Neurosurgery 113 (2011) 925–927

Fig. 1. (a–c) Perfusion CT showing the mean transit time (MTT [s]) and the regionally increased cerebral blood flow (CBF [ml/100 g/min]) and cerebral blood volume (CBV
[ml/100 g]) in the left parietal lobe; (d) Non-enhanced CT-scan; (e–g) MRI-data: exclusion of acute infarction on (e) diffusion-weighted imaging (DWI), (f) T2-weighted
imaging and exclusion of stenosing artery disease by (g) intracranial time-of-flight angiography. Right (R), Left (L).

of lorazepam 4 mg. Electroencephalography (EEG) showed a
widespread delta-focus in the left hemisphere, including a parietooccipital maximum with several sharp waves. An antiepileptic
therapy with levetiracetam was initiated (day 1: 500 mg bid,
day 2: 1000 mg bid [maintenance dose]). Subsequently, no more
clonic jerks were observed. Aphasia and right-sided hemiparesis resolved completely within the next few hours. Thereafter,
the patient reported right-sided hemihypaesthesia and hemiparaesthesia prior to the onset of his right sided hemiparesis and
aphasia, which had occurred for the first time, and for less than
a minute, two weeks before. Magnetic resonance imaging (MRI)
including MR angiography (MR-A), diffusion-weighted images
(DWI), and apparent diffusion coefficient (ADC) was performed
the following day. Cerebral ischemia and stenosing artery disease
could be excluded as well as recurrent menigeoma (see Fig. 1).
In comparison to postictal EEG, follow-up EEG showed a smaller
theta–delta-focus with a maximum left occipital and rare sharp
waves. Since then, just two episodes of headache and difficulties in
concentrating have occurred, potentially caused by focal seizures.
3. Discussion
This case demonstrates P-CT as a useful tool to differentiate
stroke and stroke-mimicking conditions in the acute setting. Initially, P-CT was performed in order to assess whether thrombolytic
therapy could be administered. Contrary to expectations, P-CT
revealed regional hyperperfusion, and further clinical course as
well as EEG revealed an epileptic origin of symptoms.
With the patient having no history of epilepsy, this first
epileptic episode was remarkable, as it presented itself as a prolonged focal inhibitory seizure. The patient was fully conscious but
noted sensory phenoma prior to the subacute onset of aphasia

and right-sided hemiparesis, which is an unusual seizure propagation phenomenon (occipital → parietal → temporal → frontal),
especially because the symptoms developed before convulsive
movements of the right leg occurred. This may also be due to a
high-frequent series of seizures, which sometimes causes unusual
propagations and symptoms (epileptic region versus symptomatic
region). In any case, during the performance of P-CT epileptic
activity was present, as hyperperfusion could not be explained otherwise. Other conditions, probably causing focal hyperperfusion,
could be excluded: CT-A and MR-A did not show signs of a vascular
pathology, and laboratory test and MRI did not show any signs of
an encephalitis.
Focal inhibitory seizures are less easily recognized, as seizures
present themselves more often with positive phenomena such
as tonic, clonic or myoclonic movements. Nonconvulsive status
epilepticus (NCSE) probably occurs more often than is generally assumed, but terminologies used in the literature have
been inconsistent. Inhibitory seizures have been described e.g. as
inhibitory epilepsy, aphasic status epilepticus or nonconvulsive
seizure paralysis and comprise entities such as focal or generalized nonconvulsive status epilepticus or subtle status epilepticus.
Inhibitory epileptic activity with inhibition of motor function has
been suggested to arise from epileptic foci in so called ‘negative
motor areas’ [1], which have been located in different association
areas. Inhibitory phenomena thus may arise from interference of
information processing in such multimodal areas.
Previous perfusion studies of patients with prolonged focal
inhibitory seizures using SPECT [2] showed regionally hyperperfused brain regions contralateral to the side of clinical symptoms,
which compares well with our findings. Cerebral perfusion measurements have been used for seizure focus determination, as
epileptic activity was found to be associated with increased

Table 1

Region of interest

Mean transit time (s)

Cerebral blood volume (ml/100 g)

Cerebral blood flow (ml/100 g/min)

Left parietal lobe (L)
Right parietal lobe (R)

3.85
3.72

39.70
12.13

618.24
195.54

C.-H. Lie et al. / Clinical Neurology and Neurosurgery 113 (2011) 925–927

metabolic demands and temporarily increased regional hyperperfusion. SPECT studies demonstrated regional hyperperfusion in the
ictal and hypoperfusion in the postictal phase. Recent MRI data is
compatible with these findings, showing regional hyperperfusion
in ictal states and providing complementary data by delineation of
associated diffusion changes in focal status epilepticus [3].
While mainly SPECT and MRI have been used before for characterization of brain perfusion alterations in ictal or periictal
conditions, P-CT data are still rare. The advantage of P-CT is that
it is broadly available and could easily be applied in the acute management of epileptic conditions. Short processing times using CT
are especially favourably in patients who need monitoring and who
do not tolerate more time-consuming examinations. Recent studies using P-CT have been promising in that they demonstrate the
feasibility of delineating regional hyperperfusion in nonconvulsive
status epilepticus [4]. Although in our case Todd’s paresis might
be discussed as a possible differential diagnosis, the clinical signs
and the observation of regional cortical hyperperfusion could be
well explained by focal nonconvulsive status epilepticus. Moreover,
the cerebral perfusion alterations are consistent with other recent
P-CT studies [4], which demonstrated cortical hyperperfusion to
be a discriminating feature of nonconvulsive status epilepticus, as
compared to postictal states. Consistent with these data, a previous
P-CT study delineated regional hypoperfusion in a case of postictal
Todd’s paresis [5]. These differential findings also suggest that the
underlying pathophysiology of postictal Todd’s paresis differs from
that of focal inhibitory seizures.

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While these observations are promising, further systematic
studies may help to validate the method and to better understand
the dynamics and the pathophysiological correlates of different
perfusion parameters using P-CT in the context of ictal and periictal
conditions.
4. Conclusion
Our case confirms the feasibility and the diagnostic value of
perfusion CT in the emergency situation, where therapeutic decisions have to be made quickly and where the clinical differentiation
between stroke and a nonconvulsive status epilepticus may not be
unequivocal.
References
[1] Luders HO, Dinner DS, Morris HH, Wyllie E, Comair YG. Cortical electrical stimulation in humans. The negative motor areas. Adv Neurol 1995;67:115–29.
[2] Bussière M, Pelz D, Reid RH, Young GB. Prolonged deficits after focal inhibitory
seizures. Neurocrit Care 2005;2(1):29–37.
[3] Szabo K, Poepel A, Pohlmann-Eden B, Hirsch J, Back T, Sedlaczek O, et al.
Diffusion-weighted and perfusion MRI demonstrates parenchymal chages in
complex partial status epilepticus. Brain 2005;128:1369–76.
[4] Hauf M, Slotboom J, Nirkko A, von Bredow F, Ozdoba C, Wiest R, et al. Cortical regional hyperperfusion in nonconvulsive status epilepticus measured by
dynamic brain perfusion CT. AJNR 2009;30(4):693–8.
[5] Mathews MS, Smith WS, Wintermark M, Dillon WP, Binder DK. Local cortical
hypoperfusion imaged with CT perfusion during postictal Todd’s paresis. Neuroradiology 2008;50(5):397–401.