Dokkyo Journal of Medical Sciences37（2）：125 〜 128，2010

125

Case Report

Lennox-Gastaut Syndrome Associated with Unilateral
Hemispheric Porencephaly
121

3George Imataka , Masahiro Ogino , Yoshiyuki Watabe , Shigeko Kuwashima ,Teisuke Hashimoto 3 and Osamu Arisaka 1
Department of Pediatrics 1 , Neurosurgery 2 and Radiology 3 ,Dokkyo Medical University School of Medicine

SUMMARY
We report an 18 year-old male with a hemispheric large porencephaly who demonstrated symptomaticWest syndrome and then developed into Lennox-Gastaut syndrome. An electroencephalogram showed anasymmetrical high voltage slow spike and wave discharges only on the right side as a side of porencephalichemisphere. Interestingly, on the opposite side of the porencephalic hemisphere, an electroencephalogram
showed a low amplitude background activity in general. In this unique features both right side hemisphericporencephaly and asymmetric high voltage slow spike and waves due to Lennox-Gastaut syndrome, theporencephalic hemisphere due to cortical parenchymal loss may be more affected than the other hemisphereby epileptiform discharge in this patient.
Key Words：Lennox-Gastaut syndrome（LGS）, porencephaly, electroencephalogram, magnetic resonanceimaging, single photon emission computed tomography

INTRODUCTION
West syndrome due to unilateral radiological lesions

spike and wave discharges.

CASE REPORT

has been often reported 1）. However, Lennox-Gastaut

The patient was born by spontaneous delivery in

syndrome（LGS）with unilateral hemispheric MRI ab-

the 36 th week of pregnancy with no asphyxia. His birthnormalities is less frequently observed, in spite of theweight was 1,618 g. During pregnancy, his mother had

fact that West syndrome can sometimes evolve intoneither infection nor received any medicine. From ear-LGS 1 〜 4, 6）.

ly infancy, his developmental milestones were delayed.

In this report, we document a rare case of a large

Neck stabilization was observed at 4 months, sitting at

unilateral porencephaly that developed into West syn-

9 months, walking at 17 months. At 1.5 year-of-age,

drome followed by LGS and then discuss the relation

motor paralysis was observed in the left upper andbetween clinically very unique patient’s EEG findings

lower limbs. Brain CT showed a large porencephaly le-with demonstrable unilateral diffuse high voltage slow

sion on the right side.
At the age of 2 years and 3 months, atonic and gen-

Received March 2, 2010；accepted May 19, 2010
Reprint requests to：George Imataka, MD.
Department of Pediatrics, Dokkyo Medical
University School of Medicine, Mibu, Tochigi
321-0293 Japaneralized tonic clonic seizures were frequently observed. An EEG showed asymmetrical right side dominant high amplitude hypsarrythmia. G-band
chromosomal analysis and amino acid, organic acid,and lactic acid levels were all normal, and a diagnosis

126George Imataka

DJMS

Fig. 1 Electroencephalogram：EEG
Interictal EEG revealed abnormal asymmetric 1.5 Hz to 2 Hz diffuse
slow spike and wave discharges predominantly in the frontal area inthe right hemisphere, which was consistent with the EEG features ofasymmetric Lennox-Gastaut syndrome.

of symptomatic West syndrome was made. ACTH

sidered, but his parents’ did not consent to the sur-therapy（0.015 mg/kg/day）by intramuscular injection

gery.

was administered for 4 weeks, then the EEG findings
improved. Subsequently, the epileptic seizures were
controlled by the administration of sodium valporate
and vitamin B6.

DISCUSSION
The patient showed the unique asymmetric EEG
features of LGS with high voltage slow spike and wave

At 12 years of age, he could run slowly while motor

discharges manifested only on the side of porencephal-paralysis was present in the left side upper and lower

ic hemisphere. Velasco et al.6） reported a similar cases

limbs. His gripping dynamiter showed 3 Kg on the left

with ours, demonstrating asymmetrical EEG activity

side and 15 Kg on the right side. Asymmetric tonic

with higher amplitude spikes and waves over the vari-seizures developed mainly in the right upper and low-ous hemispheric dysplasia diagnosed with MRI in pa-er limbs. An interictal EEG showed 1.5 to 2 Hz diffuse

tients with LGS. The definition of diffuse slow spike

irregular slow spikes and wave discharges on only theand wave discharges in LGS stress the importance ofright side alone（Fig. 1）, therefore he was diagnosed

bilateral synchrony 1 〜 4, 6）. Therefore, in this patient, thewith LGS. Asymmetric tonic seizures were controlled

unilateral diffuse slow spike and wave discharges onwith valporate, ethosuxmide, and acetazolamide. Brain

only the unilateral side is not the typical EEG features

MRI showed a large porencephaly lesion in the rightof LGS. One possible explanation is that the unilateralhemisphere（Fig. 2a, 2b）. Interictal

99m

Tc-ECD SPECT

diffuse slow spike and wave discharges EEG in our pa-

showed a decrease in blood flow in the remaining cere-tient may originate from a cerebral cortical parenchy-

bral cortex area in the right porencephalic hemisphere

mal loss due to large porencephaly. Interestingly, the（Fig. 2c, 2d）. Surgical treatment for epilepsy was con-opposite hemisphere without porencephaly showed37（2）（2010）LGS Associated with Porencephaly

12799mM agnetic resonance imaging（2a, 2b）and
Tc-ECD Single photonemission computed tomography：SPECT（2c, 2d）Brain MRI：T2-weighted images（spin echo：TR＝3,500 msec/TE＝100 msec）
revealed a large porencephaly lesion in the right hemisphere（2a, 2b）. Interictal
Fig. 299m

Tc ECD-SPECT showed a decreased perfusion of the cerebral blood flow inthe right hemisphere consistent with brain MRI images of a large porencephaly.

suppressed EEG amplitude, which may be affected bymonitoring, ictal SPECT studies and functional MRI,

the contralateral epileptiform discharges. Clinically, hisetc,will be needed before surgical indication, MRI

asymmetric tonic seizure that occurred at 12 years-of-clearly demonstrated diffuse right hemispheric pathol-age, was dominantly observed on his right limbs rath-ogy and EEG showed interictal epileptiform discharges

er than left. It may be masked by his left hemiparesis,

recorded only on this side. The patient’s family denied

inconsistent with the fact that his right hemisphere issurgical consultation and the patient has not yet been

covered by unique unilateral diffuse slow spike andsent to the presurgical evaluation.

wave discharges in this LGS. The mechanism of diffuse slow spike and wave discharges with LGS range

Acknowledgement.

This study was partly support-

from disorders of the bilateral cerebral cortices withed by the Dokkyo Medical University, Investigator-In-

disorders in the thalamus and brainstem to those ofvestigated Research Grant（No. 2010-01-6）.

the diencephalic reticular formations 5）. We think thisREFERENCES

case is a very suitable clinical example of large hemispheric MRI anomalies with cerebral parenchymal loss
with asymmetric high voltage slow spike and wave
discharges in LGS.
As for surgical treatment of this patient, he can be acandidate for right hemispherotomy. Although additional evaluations, including long-term video EEG

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George Imataka

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DJMS
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