Cystic encephalomalacia mimicking ventriculomegaly

A 6-month-old female patient presented with complaints of sudden onset high-grade fever associated with maculopapular rash and cough for three days. The mother also informed us about the noisy breathing, abnormal stiffening of the neck and all the limbs, and recurrent episodes of aspiration post-breastfeeding. The birth history was uneventful.

On ultrasonographic examination, dilatation of the third and fourth ventricles was noted with an Evans index > 0.3, suggesting ventriculomegaly. The cerebral cortex had thinned out (Figure 1), but the anterior fontanelle was depressed (Figure 2), ruling out increased pressure hydrocephalus as the cause. No aqueductal stenosis was noted. No signs of papilloedema were noted.

The MRI depicted dilatation of the third and lateral ventricles. The left lateral ventricle measured 4.37 cm, and the right lateral ventricle was 4.01 cm in a transverse section with paper thinning of cerebral parenchyma and T2 hyperintense non-enhancing areas of cystic encephalomalacia in the bilateral temporal, left occipital, and bilateral frontoparietal regions (Figures 3a and 3b). The fourth ventricle and the aqueduct of Sylvius were found to be normal.

The final diagnosis was cystic encephalomalacia with ex vacuo dilatation of the ventricular system, likely due to hypoxic ischaemic encephalopathy.

Periventricular leukomalacia (PVL) is the most common type of neuropathological form of brain damage and the leading recognised cause of cerebral palsy and cognitive impairments in premature babies [1–3]. It is mainly diagnosed by ultrasonographic examination in neonatal intensive care unit patients. Rarely, it may be diagnosed prenatally by ultrasonography; however, cystic changes are not seen until one week or more after the birth. Thus, it often goes undiagnosed when examined during this period [1].

Premature infants, mainly those born before 32 weeks of gestation, are more prone to germinal matrix bleeding, which is a precursor to PVL. In a few cases of PVL, blood may enter the ventricular system, affecting the CSF dynamics and leading to hydrocephalus formation [1]. The pathophysiology of PVL involves focal necrosis and gliosis of cellular elements located deep in cerebral white matter, with subsequent cyst formation [2,4]. Thus, the most expected sequelae to PVL are loss of white-matter volume and ventriculomegaly due to loss of myelin [4]. The aetiology mainly involves perinatal asphyxia, hypoxia, ischemia, hypotension, and inflammation of oligodendrocyte progenitor cells in the days or weeks just before the delivery [1,3].

The diagnosis of PVL is mainly based on clinicopathological and imaging correlations, like neurosonography. However, loss of myelination is primarily diagnosed on diffusion-weighted MR imaging [5,6]. On clinical examination, the newborn may have cerebral palsy, visual impairment, intellectual disabilities, hydrocephalus, and delayed developmental milestones.

Ultrasonographic examination in the early stages may show echogenicity in the periventricular region, more often in the peri-trigonal area and areas anterior and lateral to the frontal horns. In chronic stages, cyst formation may be noted [6] (Figure 1). In late stages, MR imaging may show T2 hyperintense, FLAIR-suppressed cystic areas of CSF density [6]. MRS of the affected regions shows a decrease in N-acetylaspartate (NAA) levels and an increase in NAA to choline and creatine ratios, giving indirect evidence of neuronal damage. The clinical findings, contrast enhancement, along with MR spectroscopy can help make a definite diagnosis in such extensive lesions [7].

The majority of full-term infants with mild encephalopathy generally make a full recovery. 20% of the affected newborns may not make post-neonatal periods. The remaining 25% may be affected for a lifetime by neurological impairment [8]. However, preterm neonates have an overall bad prognosis [9]. Studies mention a minimal window period of approximately 2–6 hours for successful intervention in reducing the severity of brain damage in neonates with hypoxic brain insults. Though only supportive treatment and limited intervention are available, early recognition of neonates who sustained hypoxic-ischemic insults to the brain is of extreme importance in deciding the course of management and treatment [10].

Written informed patient consent for publication has been obtained from the guardian.