Parieto-occipital encephalomalacia in children; clinical and electrophysiological features of twenty-seven cases

Abstract

Context:

Brain injuries occurring at a particular time may cause damages in well-defined regions of brain. Perinatal hypoxic ischemic encephalopathy and hypoglycemia are some of the most common types of brain injuries. Neonatal hypoglycemia can cause abnormal myelination in parietal and occipital lobes resulting in parieto-occipital encephalomalacia. There is a small number of studies about clinical and electroencephalographic (EEG) features of children with parieto-occipital encephalomalacia. They might have important neurologic sequelae such as cortical visual loss, seizures, and psychomotor retardation.

Aims:

We aimed to evaluate the causes of parieto-occipital encephalomalacia and evaluate the clinical and electrophysiological features of children with parieto-occipital encephalomalacia.

Settings and Design:

We evaluated clinical features and EEGs of 27 children with parieto-occipital encephalomalacia.

Statistical Analysis Used:

Descriptive statistics were used.

Results:

Hospitalization during the neonatal period was the most common cause (88.9%) of parieto-occipital brain injury. Eleven patients (40.7%) had a history of neonatal hypoglycemia. Twenty-three patients (85.2%) had epilepsy and nine of the epileptic patients (39%) had refractory seizures. Most of the patients had bilateral (50%) epileptic discharges originating from temporal, parietal, and occipital lobes (56.2%). However, some patients had frontal sharp waves and some had continuous spike and wave discharges during sleep. Visual abnormalities were evident in 15 (55.6%) patients. Twenty-two (81.5%) had psychomotor retardation. Fine motor skills, social contact and language development were impaired more than gross motor skills.

Conclusions:

In our study, most of the patients with parieto-occipital encephalomalacia had an eventful perinatal history. Epilepsy, psychomotor retardation, and visual problems were common neurologic complications.

Introduction

Anoxia and hypoglycemia can damage developing neonatal brain.[1] Magnetic resonance imaging of patients with symptomatic neonatal hypoglycemia can show abnormal and delayed myelination in the parieto-occipital regions of the brain.[1] Children with parieto-occipital encephalomalacia can present with neurodevelopmental deficits in later life.[2,3] Why parietal and occipital lobes are the affected regions is not exactly known.[2] Cognitive impairment, motor impairment, seizures, microcephaly, visual impairments are common reported outcomes and there is no clear indicator of later outcomes.[4,5] We aimed to evaluate the causes of parieto-occipital encephalomalacia and evaluate the clinical and electrophysiological features of children with parieto-occipital encephalomalacia.

Methods

We obtained approval for our study from Dokuz Eylul University Ethics Committee. The study was conducted in our Pediatric Neurology outpatient clinic between September 2012 and September 2013. Medical records of patients admitted during this period of time were evaluated. Patients who have encephalomalacia on parieto-occipital lobes were included in the study [Figure 1]. Hospital records of the patients were reviewed for birth date, sex, parental consanguinity, perinatal history (gestational age, birth weight, history of fetal distress), neonatal period (hypoglycemia, need for neonatal intensive care unit, neonatal convulsions), electroencephalographies (EEGs), Denver II development screen test results, evidence of epilepsy and refractory epilepsy (defined as at least one seizure during the past 6 months despite treatment with two antiepileptic drugs) seizure types, seizure frequency, visual problems, neurologic examination findings.[6] The last EEG of each patient was read again and classified as normal and abnormal. Abnormal EEGs were classified into two groups as “EEGs with nonspecific changes (slowing of the background EEG rhythm, intermittent or continuous generalized, localized or regional slowing)” and “epileptiform EEGs (spike, polyspike, sharp wave, spike wave, sharp slow wave, and polyspike wave).” Lateralization (right sided, left sided, bilateral or generalized) and localization (frontal, temporal, parietal, and occipital) of the epileptiform discharges were noted. Delay in each category of Denver II development screen test result (social contact, language, fine motor, and gross motor skills) were measured as years.

Figure 1.

Magnetic resonance imaging of a patient with parieto-occipital encephalomalacia

The study was approved by Dokuz Eylul University Ethical Committee. Informed consent was obtained from the parents of patients. SPSS, version 15 (SPSS Inc., Chicago, IL, USA), was used for statistical analysis. Potential differences in study population characteristics were calculated by Chi-square test and Mann–Whitney U-test. P < 0.05 was considered statistically significant.

Results

Twenty-seven children (6 females and 21 males) were included in the study. Mean age of the patients was 6.59 years (standard deviation = 5.01). Characteristics of patients are listed on Table 1. Eleven patients (40.7%) had neonatal hypoglycemia, 8 of them (29.6%) were born preterm and 11 of them (40.7%) had a history of perinatal hypoxia. Twenty-four (88.9%) of the patients needed hospitalization during the neonatal period. Twenty-five (92.6%) patients had a history of either neonatal hypoxia, hypoglycemia or preterm birth. 20 of them (74.1%) had neonatal seizures. Twenty-three patients (85.2%) had epilepsy and nine of the epileptic patients (39%) had refractory seizures. Neurologic examination was abnormal in 24 (88.9%) patients. Nine (33.3%) had microcephaly, 22 (81.5%) had psychomotor retardation, 15 (55.6%) had visual problems. Median delay in social contact (in years) was 1.75 (±2.81), in language was 1.75 (±2.54), in fine motor skills was 1.80 (±2.49), and in gross motor skills was 0.66 (±2.41) years.

Table 1.

Characteristics of patients with parieto-occipital encephalomalacia

Most of the patients had generalized tonic-clonic (8 patients, 29.6%), generalized tonic (5 patients, 15.8%) seizures, and infantile spasms (8 patients, 29.6%). Complex partial seizures and myoclonic seizures were also reported. EEG recordings were performed while awake in 4 (14.8%) patients and asleep in 23 (85.2%) patients. EEG on last examination was abnormal in 16 (%59.3) patients. Eight (50%) of them had bilateral, 4 (25%) had right sided, 3 (18.7) had left-sided and 1 (6.2%) had generalized epileptic discharges. Within patients with abnormal EEG, 9 (56.2%) had temporoparieto-occipital; 4 (25%) had parieto-occipital; 1 (6.2%) had parietal epileptic discharges [Figure 2]. Interestingly, one patient had bilateral frontal spike and wave discharges [Figure 3] and one of them had generalized epileptiform abnormality as continuous spike and wave discharges during sleep [Figure 4]. EEG abnormalities, seizure types and Denver II development screen test results are summarized in Table 2.

Figure 2.

Electroencephalography (EEG) of a patient with parieto-occipital encephalomalacia. The patient is 2.5 years old. EEG during sleep shows bilateral epileptiform disharges on temporal, parietal and occipital lobes

Figure 3.

Electroencephalography (EEG) of a patient with parieto-occipital encephalomalacia. EEG during sleep shows bilateral epileptiform discharges on frontal lobes

Figure 4.

Electroencephalography (EEG) of a patient with parieto-occipital encephalomalacia. EEG during sleep shows continuous spike and wave discharges

Table 2.

Seizure types, EEG abnormalities and Denver II test results of patients with parieto-occipital encephalomalacia

Neonatal hypoglycemia, neonatal hypoxia, preterm birth, hospitalization during neonatal period, history of neonatal convulsion, presence of mental motor retardation, generalized or localized EEG abnormality was not significantly associated with refractory epilepsy. Most of the patients with neonatal convulsions (90%) had psychomotor retardation, but we could not find a statistically significant association between neonatal convulsions and later psychomotor retardation (P = 0.054).

Discussion

Transient changes in blood glucose levels are commonly seen in infants during the metabolic transition period to the extrauterine environment.[2] Neonatal hypoglycemia can cause a well-defined pattern of brain injury with a tendency for the involvement of parietal and occipital white matter.[3,7,8,9] The reason for the involvement of parietal and occipital lobes is not exactly known.[10,11,12] Excitatory neurotoxins active at N-methyl-D-aspartate receptors, increased mitochondrial free radical production, initiation of apoptosis and alterations in cerebral energy production are the possible mechanisms of hypoglycemia induced cellular injury.[13,14,15,16] Parietal and occipital lobes are not especially sensitive to these effects.[17] However, it is shown that during hypoglycemia occipital lobes regional glucose uptake decreases due to the increased regional cerebral blood flow.[18] A difference in regional blood flow may help hypoglycemic damage through either loss of autoregulation or delayed hypoperfusion.[8] Neuronal injury in hypoglycemia may be limited to the areas with well-developed excitatory amino acid receptors.[8] Other comorbidities like ischemia and hypoxemia can also contribute to the brain injury.[17]

Here we evaluated the causes and clinical courses of pediatric parieto-occipital brain injury. We noticed that injury to the parieto-occipital lobes commonly occurs during the neonatal period. Only two of our patients reported an uneventful prenatal and natal history. These patients both had a history of head trauma. The remaining (25 patients; 92.6%) had complicated perinatal period such as preterm birth, neonatal hypoglycemia or hypoxia, and some of them had both. Eleven patients (40.7%) had neonatal hypoglycemia. In another study about occipital lobe injury in children, perinatal hypoglycemia was reported to be the most common cause (71.4%) of occipital lobe injury.[17] A limitation of our study was that we did not have detailed information about the lowest blood glucose level or duration of hypoglycemia in our patients. We also do not know whether the patients with a history of neonatal hypoxia or preterm birth had also coexisting hypoglycemia.

Epilepsy is a commonly reported neurologic problem in patients with parieto-occipital lobe injury.[2,17] We observed that 23 (74.1%) of our patients had epilepsy and nine of the epileptic patients (39%) had refractory seizures. Most of our patients developed seizures during the neonatal period. Nearly half of the patients had bilateral epileptiform discharges originating from temporal, parietal and occipital lobes. We did not find a significant association between the localization of the abnormal discharges and refractoriness of seizures. One of our patients had bilateral frontal discharges and one had continuous spike and wave discharges during sleep. We do not know the reason of this localization. Occipital lobe injury does not typically cause epileptic discharges whereas damage to the neighboring cortex can be the real cause.[17,19] The reason why some of these patients have refractory seizures is not known. Infantile spasms, generalized seizures, focal seizures, and febrile seizures are reported in these patients.[2] In our study, most of the patients had generalized seizures and infantile spasms. Abnormal discharges in the occipital lobe are thought to activate thalamus and reticular system causing infantile spasms.[17]

Neurologic examination was abnormal in 24 (88.9%) of our patients. Cognitive impairment, motor impairment and microcephaly were commonly noted. Tweny-two (81.5%) children had psychomotor retardation assessed by Denver II development screen test. Development of fine motor skills, language and social contact were more severely impaired than gross motor skills. Burns et al. reported that cognitive impairment was more likely than motor impairment in patients with symptomatic hypoglycemia because of the pattern of white matter injury sparing basal ganglia, thalami and posterior limb of the internal capsule.[2] Disorganization of brain tissue and epilepsy can affect mental development in these patients and mental functions were reported to improve after seizure control.[17] In our study, we could not find a significant association between psychomotor retardation and refractory seizures. However, none of the patients with normal development had refractory epilepsy. Most of our patients with neonatal convulsions (90%) had psychomotor retardation, but we could not find a statistically significant association between neonatal convulsions and later psychomotor retardation (P = 0.054).

Suboptimal head growth can be seen in patients with parieto-occipital lobe injury.[2] Nine (%33.3) of 27 children had a head circumference <3^rd percentile for age.

Visual problems is another important sequelae in children with parieto-occipital lobe injury.[17] Cortical visual impairment was observed in 15 (55.6%) of our patients. It is also not exactly known why some patients with occipital lobe injury do not have abnormal vision.[2]

In our study, we observed that most of the patients with parieto-occipital lobe injury had an eventful perinatal history like hypoxia, hypoglycemia or preterm birth, and sometimes these conditions were together. Epilepsy, psychomotor retardation, and visual impairment were the most common neurologic sequelae. Our study has some limitations. The number of patient group was small and it was a retrospective study. Further studies are needed for defining the reason why some patients with parieto-occipital encephalomalacia have less neurologic sequelae than others.