A rare case of colpocephaly with macrocephaly successfully treated with ventriculo-peritoneal shunting.

Dear Sir,

Colpocephaly refers to the condition where there is asymmetric dilatation of lateral ventricle. Usually there is gross dilatation of occipital horns but with normal caliber frontal horns. It belongs to the wider group of neuronal migration disorders characterized by malformations of the cortex caused by disruption to its normal process of formation, including proliferation, migration, and organization. Characteristically, it is typically associated with microcephaly and developmental delay. Specific symptoms include decreased IQ, visual impairment, locomotor abnormalities, muscle spasms, and seizures. We present a rare type of colpocephaly associated with macrocephaly instead of microcephaly and successfully managed with a ventriculo-peritoneal shunt.

A 5-month-old female child presented with delayed milestone development with no social smile and neck holding. Antenatal and perinatal histories were insignificant. On examination there was gross macrocephaly with head circumference being 48 cm. Anterior fontanelle was open and tense. CT scan demonstrated grossly dilated occipital and temporal horns of both lateral ventricles [Figure 1a], which were noncommunicating to each other. The frontal horns on both sides were normal with normal sized third and fourth ventricles. There was a cyst toward posterior part of septum pellucidum probably representating a persistent cavum pellucidum. MRI confirmed these features and its sagittal images clearly showed the absence of corpus callosum [Figure 1b and c]. There was a thin rim of cerebral tissue at the posterior part of both cerebral hemispheres; however, in the anterior part and posterior fossa, the brain was fully developed. A bi-ventricular ventricular peritoneal shunt was done in the hope of expansion of thin cerebral tissue. At 4-month follow-up the patient is showing improvement clinically with development of neck holding, social smile, sitting with support which are comparable to the normal development for that age. Head size has also diminished and become normal.

Figure 1

(a) Bilateral symmetrical dilated occipital horns with normal sized frontal horns and dilated posterior part of septum pellucidum. The absence of cerebral sulci suggestive of increased intracranial pressure (b) Sagittal MRI showing the absence of corpus callosum (c) T2-weighted axial MRI image showing the pathology

Colpocephaly results from the disturbed neuronal migration process and has been described as the persistence of the fetal configuration of the lateral ventricles.[1] The pathologic picture is characterized by multiple features of disturbed or arrested development of the brain, which results in diminished thickness of the cerebral white matter in the posterior portion of the centrum semiovale, giving rise to large occipital horns of the lateral ventricles. Normally, in the process of embryogenesis of brain, new neurons arise at the level of germinal matrix, located in the subependymal layer of the walls of the lateral ventricles, during the 7th week of gestation. Most of these neurons migrate from the germinal zone to their final destination in the cortex. Neurons constituting the inner layers of cortex migrate early with the exception of layer 1 neurons which migrate the earliest. Any antenatal or perinatal assault in the form of either infections such as cytomegalovirus, toxoplasmosis, toxins from metabolic disorders, and radiation exposure can interfere with the normal migration of neurons leading to various developmental anomaly of neuronal migration disorders.

Literature has reported seizures, mental retardation, and focal neurological deficits as the most common finding in colpocephaly patients.[23] Our case was significant in that it showed features of increased intracranial pressure in form of macrocephaly and tense anterior fontanelle. It prompted us to do a ventriculo-peritoneal shunt in the hope of alleviating this. Fortunately this rare type of colpocephaly with macrocephaly and increased intracranial pressure showed positive response to ventriculo-peritoneal shunt. So it emphasizes the role of CSF diversionary procedures in selected cases of colpocephaly having definite signs of increased intracranial pressure. We could not find such successful treatment of colpocephaly through ventriculo-peritoneal shunt in the literature.