Long term prognosis of symptomatic occipital lobe epilepsy ... - sepeap

Longitudinal clinical course 97
Figure 3 Sleep EEG recorded at the age of 5 years showing
frequent sharp waves in the right occipital region.
Figure 4 Sleep EEG recorded at the age of 5 years showing
frequent sharp waves in the right occipital region.
EEG and MRI findings (Table 4 and Figs. 3—5)
Interictal EEGs showed occipital or parieto-occipital spikes
in all patients (Figs. 3 and 4) during infancy and early childhood.
Frequency and amplitude of spikes were gradually
decreased and disappeared in 1 patient (Patient 3). Frontal
spikes as well as occipital spikes were also seen in 1 patient
(Patient 2). Frontal or central spikes were seen in late childhood
or adolescence in 3 patients (Patients 2—4), while their
clinical seizure symptoms went unchanged.
MRI revealed cortical atrophy and T2 prolongation in the
parieto-occipital region in 4 patients, of whom additional
frontal lesions were present in 3 patients (Figs. 2, 3 and 5).
One patient (Patient 6) showed hippocampal atrophy on both
sides without temporal lobe seizures. MRI was unremarkable
in 1 patient (Patient 4).
Discussion
It is well known that hypoglycemic brain injury predominantly
involves the occipital lobe (Murakmi et al., 1999;
Caraballo et al., 2004; Filan et al., 2006; Yalnizoglu and
Halioglu, 2007). We reported on 6 patients who had a history
of neonatal hypoglycemia and occipital lobe epilepsy
later on. Our patients had ictal symptoms compatible with
occipital lobe epilepsy, such as eye deviation, eye blinking,
staring, visual hallucinations, and ictal vomiting (Williamson
et al., 1992). Interictal EEGs showed spike waves in the
posterior region during the active periods of epilepsy in all
patients. MRI also revealed posterior cerebral damage in 4
patients. These findings indicate that epileptic foci of the
patients could mainly be caused by neonatal hypoglycemia.
Although 2 patients (Patients 4 and 6) could not be identified
with posterior cerebral lesion on MRI, they showed
typical clinical symptoms and EEG findings for occipital
lobe epilepsy. They could not be diagnosed as having idiopathic
childhood occipital epilepsy coincidentally, because
the onset and clinical course of seizures were not compatible
with those of Panayiotopoulos syndrome or Gastaut type.
They may have had very mild occipital lesions which could
not be recognized on MRI.
Perinatal hypoxic-ischemic encephalopathy in term
infants also causes parieto-occipital lobe epilepsy (Gil-Nagel
et al., 2005; Oguni et al., 2008). It is sometimes difficult to
distinguish between perinatal hypoxic-ischemic brain injury
and neonatal hypoglycemic brain injury in clinical symptoms
and neuroimaging findings. The perinatal hypoxic-ischemic
brain injury in term infants usually involves the deeper sulcal
portion of the convolutions and spares the crowns, so
called ‘‘mushroom gyri’’ or ‘‘ulegyria’’. The brain lesions
are located in parasagittal watershed vascular territories,
such as frontal and parieto-occipital lobes. It is usually more
marked in the posterior regions at the watershed zone of
the 3 major cerebral arteries. Perinatal hypoxic-ischemic
encephalopathy in term infants usually causes moderate to
severe neurological deficit, including mental or developmental
delay, motor palsy, visual impairment, and epilepsy,
while milder cases have been reported (Oguni et al., 2008).
Although EEG abnormalities and epileptic foci may be multifocal
or widespread, parieto-occipital lobe epilepsy may be
common. These two conditions sometimes coexist simultaneously
and would enhance each other, creating more brain
injury. In the series of Oguni et al. (2008), 3 of the 10
patients with parieto-occipital lobe epilepsy as sequela of
perinatal asphyxia were reported to have hypoglycemia in
the neonatal period. In the reports of neonatal hypoglycemic
encephalopathy, other associated factors including perinatal
asphyxia and fetal distress were highly present (Murakmi
et al., 1999; Yalnizoglu and Halioglu, 2007; Montassir et
al., 2009). In the present study, additional perinatal factors
which were possibly associated with brain injury other than
hypoglycemia were highly present; low birth weight for gestational
age in 5, low Apgar score in 3, neonatal seizure in 5.
MRI demonstrated abnormalities in the frontal lobe as well
as the occipital lobe in 3 patients (Patients 2, 3, and 5). MRI
of Patients 2 and 5 showed ‘‘mushroom gyri’’ or ‘‘ulegyria’’
in the posterior regions. These findings indicate that not
only hypoglycemia but also perinatal hypoxia or ischemia
played an important role in the genesis of brain injury. The
vulnerability of the brain to hypoglycemia is enhanced by
concomitant other perinatal factors. In term infants, therefore,
hypoglycemic encephalopathy and hypoxic-ischemic
encephalopathy often overlap and sometimes cannot be distinguishable
in practice. There may be some difference in
response to treatment; epileptic patients with perinatal