Ascending transaqueductal cystoventriculoperitoneal shunting in Dandy-Walker malformation: technical note

Retrocerebellar Ependymal Cyst Presenting with Obstructive Hydrocephalus in an Infant

Intracranial ependymal cysts (ECs) are rare benign lesions. They are frequently asymptomatic and arise in the supratentorial regions. Retrocerebellar ECs is a rare location. We present a case of 3-months-old infant who developed obstructive hydrocephalus, bulging fontanel, and macrocephaly secondary to a retrocerebellar EC. Magnetic resonance imaging (MRI) showed a large retrocerebellar cyst that compressed the cerebellum and the brainstem, producing fourth ventricle outlet obstruction and supratentorial hydrocephalus. Microsurgical fenestration of the cyst to the obex of the fourth ventricle and a cystic wall biopsy were performed. The procedure improved supratentorial hydrocephalus, as well as the patient's clinical condition. A histopathological study confirmed the diagnosis of an EC.

As far as we know, after a thorough review of the literature, this is the first reported case of retrocerebellar EC. It is a rare cause of hydrocephalus due to outlet obstruction of the fourth ventricle. Treatment of the cause itself was shown to be effective.

Transtentorial Distortion Syndrome: Consistent Complication Following Lateral and Fourth Ventricular Shunting in Adults

BACKGROUND

Complex hydrocephalus affecting lateral and fourth ventricles separately is occasionally managed with cerebrospinal fluid diversion via supratentorial and infratentorial ventricular catheters. The optimal configuration to reduce complications is currently unknown in adults. We describe a consistently similar clinical presentation of patients with complex hydrocephalus and a fourth ventricle separately drained by infratentorial shunt insertion.

METHODS

This was a retrospective single-center case series. Medical notes were reviewed for clinical presentation, brain imaging, and neurophysiologic tests results. All patients underwent intracranial pressure monitoring (ICPM). Outcomes were determined by ventricular appearance on brain imaging computed tomography and symptomatic improvements postoperatively.

RESULTS

Five adult patients referred to the hydrocephalus service had separate infratentorial and supratentorial shunt systems. A common clinical presentation was observed, including lower motor neuron facial palsy (confirmed with electrophysiology), ophthalmoplegia, dysarthria, impaired gait headache, and nausea. We refer to this as transtentorial distortion syndrome. Twenty-four-hour ICPM demonstrated clear low pressures. All patients underwent shunt revision connecting the transtentorial shunts via a Y-connector and the addition of a distal valve. All subjects had improved ventricular appearance on computed tomography scans post revision, and normalization of ICPM was observed. In the follow-up period of 6 months, no patient required further shunt revision.

CONCLUSION

To prevent transtentorial distortion syndrome, supratentorial and infratentorial shunt constructs in adults with encysted fourth ventricles should be similar to the shunt systems widely known in the pediatric population with Dandy-Walker syndrome (i.e., joint output to a single valve distal to the connection of the 2 proximal drainage catheters).