Unilateral hydrocephalus in paediatric patients, a trial of endoscopic fenestration.

R Kumar 
 Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, U.P., 226014, India., India

Correspondence Address:
R Kumar
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, U.P., 226014, India.
India

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::   Introduction

Unilateral dilatation of lateral ventricle is uncommon entity in children. Obstruction of one of the foramen of monro may cause hydrocephalus confined to one lateral ventricle.[1],[2] This may be secondary to wide range of causes including third ventricular tumours,[1],[3] acute or chronic inflammatory conditions,[4] subependymal gliosis,[3] arteriovenous malformations,[2] postoperative oedema,[5] cysticercosis, post shunting and overdrainage of lateral ventricle.[1] Congenital atresia of foramen of monro has also been reported.[1],[6],[7] Unilateral hydrocephalus results in clinical features of raised intracranial pressure. Various procedures have been proposed to treat the condition i.e. open third ventriculostomy, fenestration of foramen of monro as well as septum pellucidum and placement of ventriculoperitoneal shunt.[7] Two paediatric cases of asymmetrical, unilateral hydrocephalus are reported here. Endoscopic fenestration of foramen of monro and septum pellucidum was tried in these two cases of membranous occlusion of monro. The complications and results of procedure are presented here.

::   Material and methods

Two paediatric patients of asymmetrical, unilateral hydrocephalus of uncommon aetiology were managed during the last one year duration. Detailed clinical evaluation of both the cases was done. Cranial MRI was also done in first case to rule out the existence of any mass lesion in the region of foramen of monro. However, plain and contrast CT studies were done in both the cases [Table I], [Figure. 1a] and [Figure. 2]. In these patients, the foramen of monro were thought to be occluded by membrane and hence the enlarged ventricles were negotiated by Storz's rigid neuroendoscopie, through precoronal burr holes.

::   Results

The detailed clinical data is given in [Table I]. Fenestration of membrane and septum was done in both the cases. Endoscope was passed through foramen in first case to see the normal third ventricular floor, while it could not be advanced further because of bleeding from choroid plexus and membrane in second case. Bleeding was controlled by irrigation intraoperatively. Ultimately this patient required CSF diversion by unilateral shunt, suggesting the patency of the fenestrations, made in septum pellucidum. The procedure remained uneventful and successful in first case [Table I].

::   Discussion

Unilateral hydrocephalus is asymmetrical dilation of one lateral ventricle caused by obstruction of foramen of monro, and is distinct from unilateral ventricular enlargement caused by asymmetrical cerebral hypoplasia or atrophy. In review of unilateral hydrocephalus, two groups of patients are usually discussed; those who develop hydrocephalus due to acquired neoplastic or inflammatory obstruction of foramen of monro and those who appear to have congenital stenosis or atresia of the foramen of monro.[8],[9] While the acquired form occurs in children and adults, the congenital form occurs almost exclusively in children.[8] The neoplasm in third or lateral ventricle and acute or chronic inflammatory conditions are the common causes, though this uncommon entity has been attributed to many causes.[1],[3] Acquired causes include tumours at or near the foramen of monro, cysticercus cyst, post inflammatory gliosis, vascular malformation and as a consequence of shunt placement in contralateral ventricle.[7] The rare cases of idiopathic obstruction of foramen of monro fall broadly into two major categories. In some, foramen was found to be absent,[10],[11] while in others it was narrow enough to just allow the choroid plexus to pass through them.[7],[8] In second group, a thin membrane appeared to occlude the normal sized foramen.[7],[8] First case of the present report is obviously falling in second group, while the second case showed the features of both the groups, as there was narrowing of foramen along with the presence of relatively thick membrane. This picture might be the result of chronic, old healed infection or some unreported type of obstruction of foramen, which did not permit the endoscope to pass through it.



Various modes of treatment have been advocated for present condition. These include placement of shunt CSF diversion from dilated ventricle,[11] fenestration of septum pellucidum by open craniotomy, the outcome of which is thought to be favorable,[8] and fenestration of septum pellucidum by stereotactic method.[1] Dilatation of narrowed foramen was performed microscopically in a report but ventriculoperitoneal shunt had to be instituted, as patient deteriorated postoperatively.[12] Though the use of neuroendoscope in unilateral hydrocephalus was advocated as early as 1973 by Fukusima et al,[13] only few other reports mention its merits in inspecting ventricular system and the occluded foramen of monro. Cohen described the successful neuroendoscopic fenestration of occluded foramen of monro due to post operative adhesions.[14] Mohanty et al reported successful endoscopic fenestration of foramen, which was covered by thin avascular membrane.[7] Whereas the diameter of foramen of monro was normal in their case, one of the present cases had membranous occlusion of foramen of monro. In this case the procedure of neuroendoscopic fenestration was successful. Perforation of septum pellucidum was also performed. In the second case the diameter of foramen of monro was subnormal having tough vascular covering membrane, crowded by choroid plexus. The endoscopic fenestration of membrane was complicated by bleeding, hence procedure was stopped after perforation of septum pellucidum without negotiating the foramen. This case improved after unilateral shunt CSF diversion. However, it was difficult to predict whether perforation of septum was functioning here or the contralateral ventricle was dilated secondary to the shift of septum pellucidum preoperatively, which started draining after the introduction of shunt.







It seems that endoscopic inspection in cases of unilateral hydrocephalus (due to occlusion of foramen of monro) may reasonably guide about the further course of action. The fenestration of foramen of monro may be advocated if the diameter of foramen is normal and covering membrane is thin and avascular. Perforation of septum pellucidum, however, may avoid the need of biventricular shunt in cases of obstructed or narrowed foramen of monro.

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