Suhas Udayakumaran

Posterior fossa craniotomy for trapped fourth ventricle in shunt-treated hydrocephalic children: long-term outcome

OBJECT Trapped fourth ventricle (TFV) is a rare late complication of postinfectious or posthemorrhagic hydrocephalus. This entity is distinct from a large fourth ventricle because TFV entails pressure in the fourth ventricle and posterior fossa due to abnormal inflow and outflow of CSF, causing significant symptoms and signs. As TFV is mostly found in children who were born prematurely and have cerebral palsy, diagnosis and treatment options are a true challenge. METHODS Between February 1998 and February 2007, 12 children were treated for TFV in Dana Childrens Hospital by posterior fossa craniotomy/craniectomy and opening of the TFV into the spinal subarachnoid space. The authors performed a retrospective analysis of relevant data, including pre- and postoperative clinical characteristics, surgical management, and outcome. RESULTS Thirteen fenestrations of trapped fourth ventricles (FTFVs) were performed in 12 patients. In 6 patients with prominent arachnoid thickening, a stent was left from the opened fourth ventricle into the spinal subarachnoid space. One patient underwent a second FTFV 21 months after the initial procedure. No perioperative complications were encountered. All 12 patients (100%) showed clinical improvement after FTFV. Radiological improvement was seen in only 9 (75%) of the 12 cases. The follow-up period ranged from 2 to 9.5 years (mean 6.11 ± 2.3 years) after FTFV. CONCLUSIONS Fenestration of a TFV via craniotomy is a safe and effective option with a very good long-term outcome and low rate of morbidity.

Unusual subacute diencephalic edema associated with a trapped fourth ventricle: resolution following foramen magnum decompression

IntroductionA 4-year-old girl with a ventriculoperitoneal shunt presented to us with complaints of ataxia and altered consciousness. These symptoms were subacute at onset and progressive in nature.Case reportRadiological evaluation revealed a trapped fourth ventricle with brainstem compression, associated with abnormal diffuse diencephalic signal changes compatible with edema. The entrapment was managed by foramen magnum decompression, resulting in complete symptom resolution and improvement in the abnormal magnetic resonance findings.DiscussionWhile trapped fourth ventricle is a well-described entity, we could not find a similar reported case where such an acute clinical syndrome was associated with such a distinct radiological picture.ConclusionsIn this paper, we review the pre-morbid history, clinical syndrome, and imaging. We then discuss possible mechanisms, their implications on decision-making, and the preferred modes of treatment.

Temporal lobe herniation of developmental origin: a novel radiological association with open spina bifida and Chiari II malformation

Dear Editor,With regards to our recent paper on the phenomenon ofchronic uncal herniation [1], we came across an 11-year-oldchild with open spina bifida, associated with a temporallobe herniation, albeit with a difference.TheboywedescribewasbornwithanopenspinabifidaofL4level.Hehadahistoryoflumbarmyelomeningocelerepairat day1 of life. He had a ventriculoperitoneal shunt forprogressive hydrocephalus at 2 weeks of age. Subsequently,he had foramen magnum decompression when he was2 months old for persistent symptoms of brainstem compres-sionincludingrecurrentapneas.Presentlythechildhasseverepsychomotor retardation and is spastic quadriparetic.A recent follow-up MRI of the brain showed herniationof the temporal lobe and downwardly displaced occipitallobes associated with a thinned out vermis, an almostnonexistent cerebellum, thinning of the brainstem, and adeficient tentorium cerebelli (Fig. 1). His older imagingfrom his infancy demonstrated the same phenomenon oftemporal lobe herniation in association with the otheranomalies usually associated with Chiari II malformation[2, 3]. The finding of cerebral herniation in Chiari IImalformation to the best of our knowledge has previouslynot been described.In our previous paper on the similar phenomenon, wehad proposed that chronic uncal herniation was a conse-quence of the presence of a cystoperitoneal shunt and thenegative pressure gradient it created across the tentorium,and it was a treatment sequel of posterior fossa cysticcollection shunting [1]. We propose that the cerebral uncalherniation in this described child with Chiari II malforma-tion may be a sequel of the open spinal defect-associatedpressure gradient between the supratentorial compartmentand infratentorial compartment, existing prior to the closureof the CSF leak at the spinal level, analogous to thetonsillar herniation (as explained by the unified hypothesisby McLone and Knepper [4]) occurring in open spinaldefects and hence is a developmental intrauterine anomaly.The cerebral herniation probably represented an extremityof the spectrum. Note the severely hypoplastic cerebellum(“ vanishing” cerebellum [4]) in the figure (Fig. 1). It ispossible a relatively “spacious” posterior fossa instead ofthe usual tight posterior fossa, due to lack of cerebellum incombination with a widened tentorial hiatus and partlydeficient tentorium contributed to the picture in this specificchild and situation (Fig. 1). Also, the perinatal hydroceph-alus may have been contributory to the picture.Chiari II malformation is characterized by mesodermaldysplasia and premature condensation of the basilar skullanlagen, small and dysplastic lower cranial nerve ganglia,deficient tentorium cerebelli, hypoplastic and dysmorphiccerebellum, and thickened basal meninges. These anomaliesall are attributable to defective or deficient mesenchyme,which presumably deprived the skull base, hindbrain, andrhombencephalon of normal inductive effects [5].Our patient had no significant progression of neurolog-ical status; hence, probably the finding of temporal lobe

Unusual Case of ‘Trapped Fourth Ventricle’ in a Child with Posthemorrhagic Hydrocephalus – Lessons Learnt

In most of the children with posthemorrhagic hydrocephalus (PHH), multidisciplinary follow-up is performed, with the focus on consequences of prematurity, cerebral palsy (CP) and hydrocephalus. A large fourth ventricle is common in these children but imaging performed in order to document ventricles and tissue damage is not oriented to exclude coexisting rare pathologies. We report a 3-year-old child with spastic CP, secondary to prematurity and PHH. A ventriculoperitoneal shunt was inserted at the age of 2 months. On follow-up imaging the child demonstrated well-drained supratentorial ventricles with a persistent large fourth ventricle. Because of a neurological change in spasticity and new-onset torticollis, a repeat MRI was performed, suggesting a cystic, nonenhancing lesion of the fourth ventricle. The surgical exploration revealed a large dermoid of the fourth ventricle. We analyze the differential diagnosis of a clinically significant large fourth ventricle in a shunted child with PHH and CP. This includes conditions without pressure in the posterior fossa such as tissue loss due to cerebellar atrophy, or pathologies causing a true increase in pressure of the fourth ventricle (isolated fourth ventricle, cystic lesions and neoplasms of the fourth ventricle). Neurologically compromised children pose additional challenges in reaching a definitive diagnosis and hence require a careful regular assessment of their clinical status with additional well-timed imaging with appropriate protocols to allow appropriate treatment when indicated and to avoid morbidity due to delayed diagnosis. We present a rare coexistence of a dermoid tumor within the fourth ventricle in a CP child with PHH and express the dilemmas associated with its management.

Reversible diencephalic edema in trapped fourth ventricle: a diagnostic and therapeutic marker and reversal by aqueductoplasty

Dear Editor,Diagnosis and treatment schemes in a trapped fourthventricle have always been a dilemma, especially in infantsand in children with poor neurological baseline.In our previous article [1] on trapped fourth ventricle, wehad reported the occurrence of diencephalic edema inassociation with trapped fourth ventricle and had demon-strated its disappearance following foramen magnumdecompression. We had also observed that this sign mightrepresent a diagnostic sign to the trapped nature of thefourth ventricle [1]. We provide further material in supportof this concept, albeit with a few essential differences.We came across a 3-month-old prematurely born infant,who had a ventriculoperitoneal shunt (VPS) post-intraventricularhemorrhage.Hepresentedtouswithahistoryof insertion of VPS and removal secondary to shunt-relatedmeningitis. Clinically, the infant had sunset eyes, a fullanterior fontanelle, ophisthotonus, and a feeble cry.His MRI revealed dilated ventricles with multipleloculations and an enlarged fourth ventricle. The enlargedfourth ventricle was associated with a sign of brainstemcompression and transtentorial herniation. The T2-weightedsequences showed hyperintense signal changes in thediencephalon (Fig. 1). As the issue of meningitis was notsolved, we resorted to endoscopic fenestration of theloculations and an aqueductoplasty to relieve the trappedfourth ventricle. For the hydrocephalus, we continued to taphis lateral ventricles whenever the fontanelles were bulgingand the child symptomatic. The infant subsequentlyunderwent a VPS post-adequate antibiotic therapy.Postoperative MRI, 2 weeks after the aqueductoplastywhile the infant was awaiting a definitive CSF diversion,showed resolution of the signal changes in the diencepha-lon (Fig. 2). Notably, this was in present persistenthydrocephalus and signal changes elsewhere.As detailed in our previous article, the diencephalic/peri-fourth ventricular (transtentorially herniating fourth) signalchanges appeared to be secondary to pressure elevationwithin the entrapped fourth ventricle and a secondaryincrease in tissue water content [1]. Edema can occur at theareas of highest ventricular concavity, greatest expansivestress, and ependymal damage [2–4]. Additionally, vascularcompromise secondary to raised pressure, especially in the

Post CSF shunting Chiari I malformation--sequel or complication? Hypertension or hypotension?

Dear Editor: We read with great interest the article by Caldarelli et al. [1]. It is an excellent thought-provoking and truly intriguing “late complication” of CSF shunt surgery. However, we would like to take issue on few pertinent points. The authors have tried to explain this “developmental” anomaly as the result of modifications of skull growth induced by shunt, and consider this finding as a “variant” of slit ventricle syndrome. Here, we illustrate a preterm infant shunted at fourth month of infancy for posthaemorrhagic hydrocephalus, with MRI at 11 months of age showing an acquired postshunt Chiari I malformation (Fig. 1). Is “posterior fossa disproportion” enough to explain tonsillar herniation of such an early onset? The authors have not explored the possibility of intracranial hypotension secondary to shunting, primarily causing Chiari I malformation. Chiari I malformation and syringomyelia [3–5] have been described in association with cerebral hypotension, probably secondary to the sagging induced by the lack of buoyant action of intracranial CSF (one patient in the authors’ series had syringomyelia). Relief of hydrocephalus alleviating tonsillar herniation [2, 6] and contrary of shunt failure causing disappearance of tonsillar herniation [personal communication, Swift. D, March 27, 2009] have been well documented. In addition to tonsillar herniation, the authors describe thickening of the skull vault and base, increase in paranasal sinuses volume, and reduced ventricular volume, as effects of “satisfactorily working CSF shunt”. It is therefore not surprising that in this series, there is a lack of correlation of the radiological findings to the symptomatology (some patients had severe Chiari I but were asymptomatic) and the patient’s response to surgery. Out of six patients who underwent surgical treatment, only one patient underwent suboccipital craniectomy and still developed syringomyelia. Additionally, five patients underwent cranial vault enlargement, implying the posterior fossa disproportion has never been addressed or implicated directly in the authors’ series. Fig. 1 Sagittal MR of a shunted premature infant with posthaemorrhagic hydrocephalus with evidence of acquired Chiari I malformation

An Analysis of Outcome of Endoscopic Fenestration of Cavum Septum Pellucidum Cyst - More Grey than Black and White?

Background: Cavum septum pellucidum (CSP) and cavum vergae are actually fluid-filled, generally communicating midline cavities located between the third ventricle and corpus callosum. There have been various reports of their association with many behavioral and psychiatric disorders. Infrequently, they have been associated with an obstructive hydrocephalus-like picture. Although the structure and management of CSP has long been known, it has been an enigma as far as functional significance and management indications are concerned. The authors of this article try to analyze the significance of a persistent cavum and involvement of the same entity in varied presentations ranging from an incidental imaging finding to acute hydrocephalus, and propose a possible implication on the present surgical intervention paradigm. Purpose: To assess the surgical outcome of fenestration of a CSP cyst. Methods: Retrospective analysis of 3 patients who underwent endoscopic fenestration for CSP with obstructive hydrocephalus between 2012 and 2014 was done, and data were analyzed for symptomatic clinical improvement in particular behavior. Results: Pre- and postoperative brain MRI showed a significant decrease in the size of the cyst as well as the ventricles. There were no recurrences during follow-up. All of the patients improved. Conclusions: (1) Endoscopic fenestration of symptomatic CSP cysts is a safe treatment option. (2) Neurocognitive assessment is essential in the evaluation and outcome assessment of CSP.

Rare Manifestation of a Craniovertebral Junction Anomaly: Is Blue Breath Holding Always Benign?

Breath-holding or reflex anoxic seizures predominantly occur in preschool children and usually resolve by late childhood, rarely persisting through adolescence and into adulthood. Investigations are generally unnecessary. Education and reassurance is the mainstay of management. In this report, the author describes a case in which an infant presented with breath-holding spells due to a significant craniovertebral anomaly, and underwent a C1-C2 posterior stabilization. Following the stabilization of his dislocation the breath-holding spells never reappeared. Authors have previously described a rare manifestation of craniovertebral junction anomaly. Additionally, it is important to recognize that in a subset of patients breath-holding spells may be hazardous and not benign.

Cerebral cavernous malformations in the pediatric age group

Abstract Cerebral cavernous malformations (CMs) are benign intraparenchymal vascular malformations. CM represent 10%–20% of cerebral vascular lesions and their prevalence in children is around 0.5%. CMs may present at any age, however, only about 25% present during childhood. CMs are rare during the first year of life and even rarer in the neonatal and prenatal period. CMs in the pediatric age group in general, and amongst infants and neonates specifically, may have a higher bleeding tendency, distinct radiological features, and unclear natural history. In this review paper, we focus on specific features of CMs in the pediatric and infant age groups.

A bizarre reentry phenomenon of distal shunt tip causing shunt malfunction

IntroductionWe report a bizarre presentation of a distal shunt malfunction in a 5-year-old child with a ventriculoperitoneal shunt.DiscussionThe plain radiographs done as a workup for possible shunt malfunction demonstrated the distal shunt tip reentering the abdominal wall from inside the peritoneal cavity. We discuss the possible explanation for the phenomenon.ConclusionWe conclude that the case is just another reminder of the fact that shunt malfunctions can have multiple presentations; hence, a regular follow-up with appropriate imaging and high index of suspicion is mandatory in preventing morbidities.