Significance of postshunt ventricular asymmetries

Neurocysticercosis presenting as focal hydrocephalus

A 40-year-old man presented with a 2-month history of headache, nausea and vomiting, with generalised seizures for the past 15 days. On examination he had bilateral papilloedema, visual acuity was 6/6 in both eyes but perimetry showed right homonymous inferior quadrantanopia. His MRI showed numerous small cystic lesions with eccentric nodules, diffusely distributed in bilateral cerebral and cerebellar hemispheres. There was also focal hydrocephalus involving occipital and temporal horns of the left lateral ventricle leading to its selective dilation. Stool examination showed ova of Taenia solium. He was treated with albendazole, prednisone and sustained release sodium valproate for 1 month. His headache resolved and he is free of seizures. Repeat perimetry at 1 month also showed resolution of visual field defect.

Intraventricular hydatid cyst causing entrapped temporal horn syndrome: Case report and review of literature

Entrapped temporal horn is due to obstruction of one lateral ventricle in the region of trigone causing dilatation of the temporal horn. The isolated temporal horn presents itself as mass lesion. Intraventricular hydatid cyst presenting as an entrapped temporal horn has not been reported in literature till now. We report two cases of intraventricular hydatid cyst causing entrapped temporal horn.

A consensus on the classification of hydrocephalus: its utility in the assessment of abnormalities of cerebrospinal fluid dynamics

BACKGROUND

Between 2009 and 2011 an attempt has been made to develop a consensus on the classification of hydrocephalus. Clinicians and basic scientists who are recognized internationally for their work in hydrocephalus attended working meetings in which the concepts of classification of hydrocephalus were discussed at length.

PURPOSE

This review attempts to explain the relevance of a classification scheme based on the point of obstruction to the flow of cerebrospinal fluid to basic science research into the pathophysiology and effects of hydrocephalus. The review is designed to give examples of the value of this classification in analyzing research utilizing animal models. The development of hydrocephalus in the absence of a point of obstruction (true communicating hydrocephalus) is analyzed.

CONCLUSION

Contemporary neuroimaging techniques are now available that can identify the actual point of obstruction to the flow of CSF, if any, which results in the development of hydrocephalus. Such identification may lead to improved ability to analyze animal models used in hydrocephalus research as well as deciding among various treatment options.

Headaches in patients with shunts

Headache is one of the most common afflictions suffered by humans. Headache in patients with a shunt triggers a series of events that includes utilization of expensive technologies and often potentially dangerous surgical intervention. The purpose of this study was to determine the incidence of headaches in patients with shunts and, hopefully, the relationship of those headache disorders to the treatment of hydrocephalus. The Hydrocephalus Association maintains a self-reporting database recorded from individuals treated for hydrocephalus and their families. This database was mined to determine the incidence of severe headaches requiring treatment and interfering with normal life in patients who have been treated for hydrocephalus. There were 1,242 responders between the ages of 19 months and 45 years of age. Of these, 1,233 answered the question, "Do you or your family member suffer from (does your child complain of) frequent or chronic headaches?" This subset forms the basis of this study. Three groups were defined by age: children (19 months-12 years), adolescents (13 years-19 years), and young adults (20 years-45 years). Most respondents were initially treated during infancy (before 18 months of age); 84% of children and 69% of both adolescents and young adults were treated very early in life. Severe headaches became a more frequent problem as the age of the population treated for hydrocephalus increased. In terms of frequency and severity of headaches, direct comparisons with epidemiologic studies of normal populations are difficult because of the limitations of data available in the database. However, it is likely that this population has a higher incidence of severe headaches than normal populations. The cost of management of headaches in this population is very high, and the patients are at risk throughout life. Early treatment decisions have a significant effect on later quality of life. Strategies that lead to normalization of cerebrospinal fluid dynamics and life without shunt dependency are justified if they can be shown to improve later quality of life.

The importance of the cortical subarachnoid space in understanding hydrocephalus

OBJECT

In this paper the authors define the role of the cortical subarachnoid space (CSAS) in poorly understood forms of hydrocephalus to cerebrospinal fluid (CSF) dynamics to improve understanding of the importance of the CSAS and its role in selecting patients for endoscopic third ventriculostomy (ETV). The secondary purpose of this work was to define testable hypotheses to explain enigmatic disorders of CSF dynamics and to suggest how these concepts could be tested.

METHODS

The magnitude of the contribution of the CSAS is explored using the solid geometry of concentric spheres. With this starting point, clinical conditions in which CSF dynamics are not easily understood are explored regarding the potential role of the CSAS. Overall, problems of CSF dynamics are easily understood. Insights may be gained when the results of a pathological process or its treatment vary from what has been expected.

RESULTS

Acute changes in ventricular volume at the time that hydrocephalus develops, the failure of shunts, and the changes in ventricular volume with shunt repair may occur very rapidly. Changes in the volume of water in the brain, especially in the brain substance itself, are unlikely to occur at this rapid rate and may be interpreted as a simple redistribution of the CSF between the ventricle and CSAS with no initial change in the actual volume of brain parenchyma. Problems such as pseudotumor cerebri, shunt failure with nonresponsive ventricles, and negative-pressure hydrocephalus can be explained by assessing the ability of ventricular CSF to flow to the CSAS and the ability of this fluid to exit this compartment. Ventricular enlargement at the time of shunt failure implies a failure of flow between the ventricles and CSAS, implying that all patients who show this phenomenon are potential candidates for ETV.

CONCLUSIONS

The important role of the CSAS in the pathophysiology of various forms of hydrocephalus has been largely ignored. Attention to the dynamics of the CSF in this compartment will improve understanding of enigmatic conditions of hydrocephalus and improve selection criteria for treatment paradigms such as ETV. These concepts lead to clearly defined problems that may be solved by the creation of a central database to address these issues.

Severe intracranial hypertension in slit ventricle syndrome managed using a cisterna magna–ventricle–peritoneum shunt

OBJECT

Severely increased intracranial pressure (ICP) can be life threatening in patients who had previously undergone shunt treatment but who do not experience ventricular enlargement. The authors analyzed the utility of placing shunts into the cisterna magna concurrently with ventricular shunts in patients who were not candidates for lumboperitoneal (LP) shunt placement.

METHODS

Ten patients treated with cisterna magna-ventricle-peritoneum (CMVP) shunts for complex problems of shunt function were reviewed retrospectively. All patients had documented increases in ICP and ventricles that did not expand despite life-threatening increases (> 80 mm Hg in one case) in ICP. Between 1995 and 2003, 10 patients (four males and six females, age range 4-32 years) were identified as having life-threatening increases in ICP despite small or slit-like ventricles on imaging studies. Each episode was documented with intraparenchymal pressure monitoring. All patients had documented ventricular catheter failures at the time of the intervention, and all had undergone at least one previous attempt to treat the condition with a valve upgrade and replacement of the ventricular catheter. Three patients had achondroplasia, four had spina bifida, and three had a preexisting Chiari malformation Type I. All patients improved after the procedure, and none suffered permanent complications. For at least 48 hours after surgery, all patients underwent intraparenchymal monitoring of ICP (an intraparenchymal monitor was used that documented normal ICP).

CONCLUSIONS

The CMVP shunts are an excellent option for patients who are not candidates for LP shunts but who have high ICP and ventricles that do not enlarge at shunt failure. The ability to access the spinal fluid in the cortical subarachnoid space presumably accounts for this success.

Influence of the shunt type in the difference in reduction of volume between the two lateral ventricles in shunted hydrocephalic children

INTRODUCTION

After shunt insertion there is commonly a disproportionate reduction in size of the lateral ventricle containing the catheter (shunted lateral ventricle), which is almost certainly related to shunt function. To explore the difference between two shunt types, the Differential Pressure Medium Pressure cylindrical (M.P.) and Delta 1.5 valves (manufactured by P.S. Medical, Goleta, CA, USA), we measured lateral ventricle volumes preoperatively and after 3 months, using segmentation techniques on CT or MR scans.

MATERIALS AND METHODS

There were 40 patients (mean age 65.7 months), 17 with M.P. and 23 with Delta valves. There were 22 new shunts (8 M.P. and 14 Delta), and 18 revisions (9 M.P. and 9 Delta). Shunted to non-shunted ventricle volume ratios and the difference in ratios (preoperative to 3 months) was calculated. A ratio considerably less than 1 would indicate disproportionate reduction in the volume of the shunted ventricle in comparison to the non-shunted one.

RESULTS

In the new shunt group, the preoperative ratio was 1.63 for M.P. and 1.07 for Delta (p=0.148, one-way ANOVA). The 3-month ratio was 0.71 for M.P. and 1.44 for Delta. The difference in ratios was 0.91 for M.P. and -0.36 for Delta (p=0.042, one-way ANOVA). There were 4 shunt obstructions in this group (3 with M.P. and 1 with the Delta valve). In the revision group, the preoperative ratio was 0.85 for M.P. and 0.88 for Delta (p=0.859, one-way ANOVA). The 3-month ratio was 0.74 for M.P. and 0.60 for Delta. The difference in ratios was 0.11 for M.P. and 0.27 for Delta (p=0.274, one-way ANOVA). There were 5 shunt obstructions in this group (2 with M.P. and 3 with the Delta valve). No correlation was found between incidence of shunt obstruction and shunt type or ventricular volume ratio difference (preoperative to 3 months) in either of the two operation groups.

CONCLUSIONS

Following new shunt insertion, the presence of a differential pressure valve results in early significant reduction in the shunted lateral ventricle volume. This may predispose to shunt obstruction although this study has not proven this. This effect was not observed with the Delta valve after 3 months. Following shunt revision, no difference between the two valve types was observed. This may indicate a chronic effect of the presence of a shunt on the ventricular system size, obviating the effect of different shunt types.

The effect of intracranial hypotension on cerebral blood flow in a feline model

Intracranial hypotension is a known clinical entity but its pathophysiology has been meagerly studied. Any setting with cerebrospinal fluid leakage or drainage can cause intracranial hypotension. A feline model of kaolin induced chronic hydrocephalus with controlled cerebrospinal fluid drainage from a lateral ventricle yields reproducible intracranial hypotension of up to -15 torr for several hours to -80 torr of about 10 minutes. The magnitude of this hypotension is significantly greater than can be attained by cisterna magna drainage. This new model allows multiple cerebral parameters to be studied during intracranial hypotension. In 11 cats with stable blood pressure and intracranial hypotension of at least -15 torr, regional blood flow utilizing the hydrogen clearance method in the cerebral cortex and subcortical nuclei was unchanged relative to the baseline. These results imply that: 1) cerebral vascular autoregulation is maintained during significantly increased perfusion pressure due to negative intracranial pressure, 2) the symptomatology of clinical intracranial hypotension is not due to decreased cerebral perfusion.

Age-related changes of cerebral ventricular size. Part II: Normalization of ventricular size following shunting

Thirty-one hydrocephalic patients were investigated prospectively by means of computed tomographic scan performed prior to and one week after cerebrospinal fluid (CSF) shunting. Planimetric measurements of the size of the cerebral ventricles were compared before and after shunting. Children under two years of age and elderly patients showed significantly less reduction of ventricular size (8.5 +/- 6.3% and 9.7 +/- 3.5% respectively) than older children and young adults (61.2 +/- 5.2%). The degree of reduction of ventricular size did not correlate with pre-operative size of ventricles, duration of disease, or clinical improvement. These findings suggest that reduction of ventricular size following CSF shunting is related to age. We postulate that the size of cerebral ventricles in hydrocephalic patients is not exclusively related to CSF dynamics, but also depends upon the intrinsic elastic properties of the cerebral parenchyma which vary with age.

Subdural fluid collections following transcortical approach to intra- or paraventricular tumours

Subdural fluid collections appeared in 15 cases (39%) after removal of 38 intra- and paraventricular tumours in the third or lateral ventricle through 18 frontal and 20 parietal transcortical approaches. Transient fluid collections which disappeared within 2 weeks occurred in 6 cases (16%) and persistent ones in 9 cases (24%). Four of the 9 cases (11%) of collections required surgical treatment because of positive clinical signs and symptoms. Two cases had expansive fluid collections and the other two contained subdural haematomas at surgery. The risk factors likely to contribute to a persistent collection were preoperative ventriculomegaly (frontal horn index greater than 0.38) and a frontal transcortical approach. A symptomatic collection should be considered as a potential complication of the transcortical approach to intraventricular tumours and some methods should be devised to prevent it when intra- or paraventricular tumours with ventriculomegaly are removed.

Entrapment of the temporal horn: a form of focal obstructive hydrocephalus

Three cases of a form of focal hydrocephalus are described which the authors term "entrapment of the temporal horn". Obstruction of one lateral ventricle in the region of the trigone isolates the temporal horn. Continued secretion of cerebrospinal fluid within the temporal horn causes it to behave as a mass lesion. In the cases described the causes of the condition were recurrent glioma, previous tuberculous meningitis and surgical excision of an arteriovenous malformation which extended into the trigone. Shunting of the trapped temporal horn provides satisfactory treatment.

Asymmetrical hydrocephalus following ventriculitis from rupture of a thalamic abscess

Ventriculitis developed suddenly in a patient with an undiagnosed abscess and was accompanied by obtundation, fever, meningismus, and hemiplegia. Aspiration of a streptococcal thalamic abscess and high doses of intravenous penicillin produced marked improvement. Increasing dysphasia 5 weeks later was accompanied by ventricular dilatation, most marked on the left, with no evidence of recurrent abscess. The left foramen of Monro was demonstrably patent. Shunting relieved the symptoms of aphasia; they recurred with one episode of malfunction of the shunt. This case lends support to the belief that parenchymal characteristics are important in hydrocephalus and demonstrates how asymmetrical ventricular dilatation can produce focal symptoms.

Subtemporal decompressions for shunt-dependent ventricles: mechanism of action

The literature suggests that subtemporal decompression is an effective treatment for the syndrome of shunt-dependent ventricles because it allows the ventricle to enlarge around the shunt catheter tip. Pre- and post craniectomy ventricular areas were measured from computed tomography scans with a computer digitizing technique in three patients with this syndrome who had undergone four surgical procedures. All patients improved symptomatically following craniectomy. A significant decrease in total ventricular area was noted in all instances. The results suggest that subtemporal craniectomy causes the ventricles to become smaller, not larger. Other possible explanations for the effectiveness of the procedure are discussed.