Seizure as the Early and Main Manifestation of Infantile Vanishing White Matter Disease: A Case Report

Childhood leukodystrophies consist of various inherited white matter disorders with an incidence ranging from 1.2 to 3.01 per 100,000 persons/year (1). Vanishing white matter disease (VWM) is an autosomal recessive disorder and one of the most common types of leukodystrophies and engages all ages including antenatal, infantile, early childhood, late childhood, and adults (2). No data exists regarding the exact incidence of VWM; however, it seems that this type of leukodystrophy is more common in Caucasians. It has also been reported in non-white cases from South America and Asia.

The molecular basis of the disease has been shown to be due to mutations in any of the five genes encoding subunits of eukaryotic translation initiation factor B (eiF2B). These genes are known as EIF2B1-5. EIF2B is considered as an important molecule which plays a significant role in the protein synthesis and managing the cellular stress conditions. To date, more than 110 mutations have been discovered in EIF2B genes; mostly recognized in EIF2B5, followed by EIF2B4 and EIF2B2 genes (3).

The infantile form of the disease appears before the age of 2 years and usually is determined by hypotonia, progressive neurological deterioration, cerebellar ataxia, early onset cataracts, spasticity, fever and vomiting (3). Moreover, only few cases of early onset or infantile type of vanishing white matter disease with refractory seizures have been reported (2, 3).

Here, we report the clinical and radiologic findings of a boy with infantile type of vanishing white matter disease who was presented with early onset serial seizures at 4 months of age. Molecular genetic evaluations indicated a mutation in EIF2B2 gene which confirmed the disease.

The patient is a 12 month old boy who was born at term to a consanguinous couple with birth weight of 2550 grams and head circumference of 34cm. His parents brought him to a primary care physician at 2 months of age due to his poor weight gain. At 4 months, frequent seizures with staring, clonic movements of the left side limbs and truncal hypotonia developed. Therefore, the patient was referred to our hospital (children’s Medical center) for further evaluation. Neurological examinations did not show spasticity nor exaggerated deep tendon reflexes, but axial hypotonia was present. Neurological deterioration was not recognized. Awake electroencephalography (EEG) at age of 4 months showed tonic and focal seizures consisting of flattening of the background preceded by generalized and multifocal spike waves followed by diffuse slow waves. Brain magnetic resonance imaging (MRI) was performed at the time of seizure onset for further evaluation (Figure 1). Brain MRI transverse spin echo (SE) T2 weighted images at the level of midbrain and high parietal centrum semi-oval demonstrated diffuse abnormally increased signal of deep and subcortical white matter. In addition, bilateral higher signal of anterior temporal subcortical white matter in T2 weighted image compared to deep white matter suggested early cystic degeneration in these areas. Coronal SE T2 weighted image and T1 fluid attenuated inversion recovery (FLAIR) sequences at the level of posterior limb of internal capsule and dentate nuclei indicated diffuse supra and infratentorial white matter increased signals which were relatively low in T1 FLAIR. Overall findings were consistent with severe demyelination of white matter. We considered a demyelinating type of childhood leukodystrophy as the probable etiology for the clinical scenario of this patient regarding to MRI pattern involvement, early onset refractory seizures and global developmental delay. Seizures of the patient stopped with intravenous anti-epileptic medications and he was discharged 2 weeks later with phenobarbital. Basic metabolic tests were all normal; therefore performing of molecular study was discussed with parents to establish the diagnosis.

In his follow-up, truncal tone was improved with occupational therapy at the age of 6 months; however, he experienced frequent tonic seizures unresponsive to anti-epileptic drugs at 7 months of age. Therefore, the patient was admitted to pediatric intensive care unit (PICU) of our hospital for 1 month for better control of seizures. The patient was discharged from the hospital with oral phenobarbital, phenytoin and levetiracetam. By obtaining informed consent from parents blood sample of the patient was sent to laboratory for molecular studies.

Two weeks later at the age of 8.5 months the patient was hospitalized again with decreased level of consciousness and 5 to 6 times of tonic seizures per day. Meanwhile, he experienced respiratory failure in PICU. Intubation was performed; followed by tracheostomy due to long term intubation.

And now, at the age of 12 months, the patient is discharged from hospital and his seizures are under control by phenobarbital, topiramate, lamotrigine, and oxcarbazepine. His respiration is supported by mechanical ventilation through T-tube and oxygen therapy. The last systemic and neurologic examinations showed central hypotonia, microcephaly, dense cataract, global developmental delay and poor weight gain. The results of molecular studies at age 12 months showed the final diagnosis.

Frequent seizures were the main manifestation in this patient. As seizure occurrs in rare cases of infantile VWM, suspecting this type of leukodystrophy as a potential diagnosis in the early stage of the disease in this patient was not possible. To date, no specific algorithmic approach has been introduced for diagnosis of leukodystrophies. However, clinical scenario of individuals, imaging findings and MRI pattern involvement, and genetic tests are the three main dimensions for diagnosis. In this study, the most common clinical presentations of VWM were not observed in the early stage of the disease, but hypotonia. It took about 8 months after the first episodes of seizures until other clinical features; including microcephaly and cataract, were recognized. Up to now features like spasticity, ataxia and fever have not been observed. Although the overall clinical presentations were confusing and couldn’t lead to diagnosis, demyelinating pattern in MRI and reported homozygous mutation in EIF2B2 gene make the diagnosis of VWM definite. It is worth to mention that although genetic analysis is the most suitable modality for diagnosis of VWM and other types of leukodystrophies; its high cost and late response are the biggest challenges of its use. Therefore, to reduce the economic burden of diagnosis of leukodystrophies one should focus more on clinical presentations and imaging MRI findings as much as possible.

To date only few cases of early onset VWD have been reported in whom frequent seizures have been prominent as clinical manifestations of the disease. These are listed in Table 1. In one study epilepsy occurrence coincided with various other manifestations of VWD (5); yet another one reported seizure as the only clinical manifestation (6). Like our study, 2 of these trials reported mutations in EIF2B2 gene. However, the DNA levels of mutation were different. Leng et al. (7) reported a patient with a compound heterozygous mutation in EIF2B2 gene that caused by c.254T4A, p. Val85Gly mutation in father and c.922G4A, p.Val308Met mutation in mother; however, homozygosity of the mutations in our patient is due to consanguineous marriage of his parents.

The study was approved by ethics committee of children’s hospital center, pediatric center of excellence.