Contralateral Lateral Ventricle Research Articles

The Device for Intraventricular Entry guide: a novel solution to a perpetual problem.

The authors designed a low-profile device for reliable ventricular access and prospectively studied its safety, efficacy, and accuracy at a large academic center. A novel device for ventricular entry, the Device for Intraventricular Entry (DIVE) guide, was designed and created by the first and senior authors. Fifty patients undergoing external ventricular drainage (EVD) or shunt placement were prospectively enrolled for DIVE-assisted catheter placement at a single academic center. The primary outcome was the catheter tip location on postprocedural CT. Secondary outcomes included number of catheter passes, clinically significant hemorrhages, and procedure-related infections. Fifty patients were enrolled. Indications included subarachnoid hemorrhage, intraventricular hemorrhage, traumatic brain injury, hydrocephalus, pseudotumor, and postsurgical wound drainage. In total, 76% (38/50) of patients underwent right-sided placement and 24% (12/50) underwent left-sided placement. All 100% (50/50) of patients had successful cannulation with an average of 1.06 passes. Postprocedural head CT confirmed ipsilateral frontal horn or third ventricle placement (Kakarla grade 1) in 92% (46/50) of patients and placement in the contralateral lateral ventricle in 8% (4/50) (Kakarla grade 2). There were no clinically significant track hemorrhages or procedural infections. This single-center prospective study investigated the safety and efficacy of DIVE-assisted ventricular access. In total, 100% of procedures had successful ventricular cannulation, with 92% achieving Kakarla grade 1, with an average of 1.06 passes without any clinical complications.

Accuracy, Hemorrhagic Complications and CT Radiation Dose of Emergency External Ventricular Drain (EVD) Placement in Pediatric Patients: A 15-Year Retrospective Analysis.

To assess accuracy, the frequency of hemorrhagic complications and computed tomography (CT) radiation dose parameters in pediatric patients undergoing landmark-guided external ventricular drain (EVD) placement in an emergency setting. Retrospective analysis comprised 36 EVD placements with subsequent CT control scans in 29 patients (aged 0 to 17 years) in our university hospital from 2008 to 2022. The position of the EVD as well as the presence and extension of bleeding were classified according to previously established grading schemes. Dose length product (DLP), volume-weighted CT dose index (CTDIvol) and scan length were extracted from the radiation dose reports and compared to the diagnostic reference values (DRLs) issued by the German Federal Office for Radiation Protection. After the initial EVD placement, optimal positioning of the catheter tip into the ipsilateral frontal horn or third ventricle (Grade I), or a functional positioning in the contralateral lateral ventricle or the non-eloquent cortex (Grade II), was achieved in 28 and 8 cases, respectively. In 32 of 36 procedures, no evidence of hemorrhage was present in the control CT scan. Grade 1 (<1 mL) and Grade 2 (≥1 to 15 mL) bleedings were detected after 3 and 1 placement(s), respectively. For control scans after EVD placements, CTDIvol (median [25%; 75% quartile]) was 39.92 [30.80; 45.55] mGy, DLP yielded 475.50 [375.00; 624.75] mGy*cm and the scan length result was 136 [120; 166] mm. Exceedances of the DRL values were observed in 14.5% for CTDIvol, 12.7% for DLP and 65.6% for the scan length. None of these values was in the range requiring a report to the national authorities. Landmark-based emergency EVD placement in pediatric patients yielded an optimal position in most cases already after the initial insertion. Complications in terms of secondary hemorrhages are rare. CT dose levels associated with the intervention are below the reportable threshold of the national DRLs in Germany.

768 The Device for Intraventricular Entry (DIVE) Guide: A Novel Solution to a Perpetual Problem

INTRODUCTION: Safe and reliable access to the ventricular system is a necessary skill in the neurosurgical armamentarium. The freehand technique for catheter placement remains an accepted method, yet the inaccuracy rate can be as high as 40%, with as many as 3 passes per procedure, and complication rates between 10-40%. A number of devices have been developed to assist with catheter placement, however, these devices inhibit ergonomics or require larger incisions and expensive navigation technology. METHODS: A novel device for ventricular entry, the DIVE guide, was designed by the first and senior author. 50 patients undergoing extra ventricular drain (EVD) or shunt placement were prospectively enrolled for DIVE assisted catheter placement under an IRB approved study with a non-significant risk (NSR) device designation. The primary outcome is catheter location on CT. Secondary outcomes include number of catheter passes, clinically significant hemorrhages and procedure-related infections. RESULTS: 50 patients were enrolled at a single academic center for ventricular access with DIVE assistance. Indications included subarachnoid or intraventricular hemorrhage, TBI, hydrocephalus, pseudotumor and post-surgical wound drainage. 76% (38/50) underwent right sided placement and 24% (12/20) underwent left. 100% (50/50) had successful cannulation in an average of 1.06 passes. Post procedure head CT confirmed ipsilateral frontal horn or 3rd ventricle placement (Kakarla Grade 1) in 92% (46/50) and 8% (4/50) in the contralateral lateral ventricle (Grade 2). There were no significant tract hemorrhages or procedural infections. CONCLUSIONS: This a prospective study to investigate the safety and efficacy of DIVE-assisted ventricular access. 100% of procedures had successful ventricular cannulation, with 92% achieving Kakarla Grade 1, in an average of 1.06 passes.

Palliative ventriculoperitoneal shunting in dogs with obstructive hydrocephalus caused by tumors affecting the third ventricle.

BackgroundHypertensive or obstructive hydrocephalus is a common complication in dogs with tumors affecting the third ventricle for which few therapeutic options are available.ObjectivesTo describe signalment, neurological status, and pre‐ and postsurgical findings, complications and survival time in 4 dogs with obstructive hydrocephalus caused by third ventricle tumors that were palliatively treated using ventriculoperitoneal shunting (VPS).AnimalsFour client‐owned dogs with obstructive hydrocephalus caused by tumors affecting the third ventricle.MethodsMedical records were reviewed for dogs diagnosed with third ventricular tumors. Inclusion criteria were complete medical record, advanced diagnostic imaging for review, and VPS as sole surgical treatment.ResultsAt the time of diagnosis, all patients displayed acute onset and rapidly progressive diffuse intracranial clinical signs. On advanced imaging, all dogs had a homogeneously enhancing mass occupying or collapsing the third ventricle as well as obstructive hydrocephalus. All of the dogs underwent VPS of the most dilated lateral ventricle. In 2 of the patients, intracranial hypertension followed by normotension after VPS placement was confirmed intraoperatively by means of direct intracranial pressure monitoring. Excellent clinical improvement was observed in all dogs immediately after surgery. Three patients required a second VPS in the contralateral lateral ventricle 3, 7 and 11 months after the first surgery, all of them with renewed improvement in clinical signs.Conclusion and Clinical ImportanceVentriculoperitoneal shunting is a rapid and effective treatment for patients with obstructive (hypertensive) hydrocephalus caused by tumors located within the third ventricle.

Subventricular zone volumetric and dosimetric changes during postoperative brain tumor irradiation and its impact on overall survival

PurposeThe aim of this retrospective study was to investigate the relationship between the dose to the subventricular zone (SVZ) and overall survival (OS) of 41 patients with glioblastoma multiforme (GBM), who were treated with an adaptive approach involving repeated topometric CT and replanning at two-thirds (40 Gy) of their course of postoperative radiotherapy for planning of a 20 Gy boost. MethodsWe examined changes in the ipsilateral lateral ventricle (LV) and SVZ (iLV and iSVZ), as well as in the contralateral LV and SVZ (cLV and cSVZ). We evaluated the volumetric changes on both planning CT scans (primary CT1 and secondary CT2). The survival of the GBM patients was analyzed using the Kaplan–Meier method; the multivariate Cox regression was also performed. ResultsMedian follow-up and OS were 34.5 months and 17.6 months, respectively. LV and SVZ structures exhibited significant volumetric changes on CT2, resulting in an increase of dose coverage. At a cut-off point of 58 Gy, a significant correlation was detected between the iSVZ2 mean dose and OS (27.8 vs 15.6 months, p = 0.048). In a multivariate analysis, GBM patients with a shorter time to postoperative chemoradiotherapy (<3.8 weeks), with good performance status (≥70%) and higher mean dose (≥58 Gy) to the iSVZ2 had significantly better OS. ConclusionsSignificant anatomical and dose distribution changes to the brain structures were observed, which have a relevant impact on the dose-effect relationship for GBM; therefore, involving the iSVZ in the target volume should be considered and adapted to the changes.

Enhanced Homing of Mesenchymal Stem Cells Overexpressing Fibroblast Growth Factor 21 to Injury Site in a Mouse Model of Traumatic Brain Injury.

Mesenchymal stem cells (MSCs) are emerging as a potential therapeutic intervention for brain injury due to their neuroprotective effects and safe profile. However, the homing ability of MSCs to injury sites still needs to be improved. Fibroblast Growth Factor 21 (FGF21) was recently reported to enhance cells migration in different cells type. In this study, we investigated whether MSCs that overexpressing FGF21 (MSC-FGF21) could exhibit enhanced homing efficacy in brain injury. We used novel Molday IONEverGreen™ (MIEG) as cell labeling probe that enables a non-invasive, high-sensitive and real-time MRI tracking. Using a mouse model of traumatic brain injury (TBI), MIEG labeled MSCs were transplanted into the contralateral lateral ventricle followed by real-time MRI tracking. FGF21 retained MSC abilities of proliferation and morphology. MSC-FGF21 showed significantly greater migration in transwell assay compared to control MSC. MIEG labeling showed no effects on MSCs’ viability, proliferation and differentiation. Magnetic resonance imaging (MRI) revealed that FGF21 significantly enhances the homing of MSC toward injury site. Histological analysis further confirmed the MRI findings. Taken together, these results show that FGF21 overexpression and MIEG labeling of MSC enhances their homing abilities and enables non-invasive real time tracking of the transplanted cells, provides a promising approach for MSC based therapy and tracking in TBI.

Proximal ventricular shunt malfunctions in children: Factors associated with failure

Ventricular shunt failures and subsequent revisions are a significant source of patient morbidity. We conducted a review of pediatric patients undergoing placement or revision of ventricular shunts at our institution between January 2007 and December 2008. Patients were followed through to July 2014. Data collected included patient demographics, shunt history and indication for procedure, approach taken for shunt placement, and location of shunt tip in relation to the foramen of Monro. Univariate and multivariate analyses were conducted to identify factors associated with proximal failure. A total of 87 procedures were identified in 40 patients, consisting of 23 initial placements and 64 revisions. Thirty-nine proximal catheter malfunctions were identified. Indications for shunt placement included Chiari II malformation (33%) and intraventricular hemorrhage (33%). Mean follow-up period was 5.5years. Median time to shunt failure was 1.57years. In the multivariate model, younger age at placement was associated with decreased time to proximal failure (hazard ratio [HR]=0.80 per increasing year of age, 95% confidence interval [CI] 0.64–0.98). Both anterior approach (HR=0.39, 95% CI 0.23–0.67) and farther distance to foramen of Monro (HR=0.02 per increasing 10mm, 95% CI 0.00–0.22) were associated with increased time to proximal failure when the catheter tip was located within the contralateral lateral ventricle. Optimizing outcomes in patients with shunt-dependent hydrocephalus continues to be a challenge. Despite unsatisfactory outcomes, particularly in the pediatric population, few conclusions can be drawn from studies assessing operative variables.

A novel single twist-drill access device for multimodal intracranial monitoring: a 5-year single-institution experience.

Multimodal intracranial monitoring in the neurosurgical patient requires insertion of probes through multiple craniostomies. To report our 5-year experience with a novel device allowing multimodal monitoring though a single twist-drill hole. All devices (Hummingbird Synergy, Innerspace) were placed at the Kocher point between 2008 and 2013 at our institution. An independent clinical research nurse prospectively collected data on all bedside placements. Placement accuracy was graded on computed tomography scan as grade 1 (ipsilateral frontal horn or third ventricle), grade 2 (contralateral lateral ventricle), and grade 3 (anywhere else). Infection was monitored with serial cerebrospinal fluid samples. Two hundred seventy-five devices (198 at bedside, 77 in operating room) were placed in patients with spontaneous subarachnoid hemorrhage (49%), traumatic brain injury (47%), and others (4%) for a median duration of 6 days. A junior (postgraduate year 1-2), midlevel (postgraduate year 3-4), or senior resident (postgraduate year 5-6) placed 39%, 32%, and 29% of the devices, respectively. Ninety-two percent of all devices placed were draining cerebrospinal fluid, ie, were grade 1 (75%) or 2 (17%). Placement accuracy did not vary with level of training. Complications included hemorrhage (10%) and infection (4%), with 1 patient requiring intraparenchymal hematoma evacuation and a second requiring abscess drainage. These rates were lower than reported in the literature for standard external ventricular drains. Hummingbird Synergy is a novel single-port access device for multimodal intracranial monitoring that can be placed safely at the bedside or in the operating room with placement accuracy and has a complication profile similar to or better than that for standard external ventricular drains.

Accuracy and Safety of Bedside External Ventricular Drain Placement at Two Different Cranial Sites : Kocher's Point versus Forehead

External ventricular drain (EVD) is commonly performed with a freehand technique using surface anatomical landmarks at two different cranial sites, Kocher's point and the forehead. The aim of this study was to evaluate and compare the accuracy and safety of these percutaneous ventriculostomies. A retrospectively review of medical records and head computed tomography scans were examined in 227 patients who underwent 250 freehand pass ventriculostomy catheter placements using two different methods at two institutions, between 2003 and 2009. Eighty-one patients underwent 101 ventriculostomies using Kocher's point (group 1), whereas 146 patients underwent 149 forehead ventriculostomies (group 2). In group 1, the catheter tip was optimally placed in either the ipsilateral frontal horn or the third ventricle, through the foramen of Monro (grade 1) in 82 (81.1%) procedures, in the contralateral lateral ventricle (grade 2) in 4 (3.9%), and into eloquent structures or non-target cerebrospinal space (grade 3) in 15 (14.8%). Intracerebral hemorrhage (ICH) >1 mL developed in 5 (5.0%) procedures. Significantly higher incidences of optimal catheter placements were observed in group 2. ICH>1 mL developed in 11 (7.4%) procedures in group 2, showing no significant difference between groups. In addition, the mean interval from the EVD to ventriculoperitoneal shunt was shorter in group 2 than in group 1, and the incidence of EVD-related infection was decreased in group 2. Accurate and safe ventriculostomies were achieved using both cranial sites, Kocher's point and the forehead. However, the forehead ventriculostomies provided more accurate ventricular punctures.

Brain-Derived Neurotrophic Factor Contributes to Recovery of Skilled Reaching After Focal Ischemia in Rats

Brain-derived neurotrophic factor (BDNF) is involved in neuronal survival, synaptic plasticity, learning and memory, and neuroplasticity. Further, exogenous treatment with BDNF or exposing animals to enrichment and exercise regimens, which also increase BDNF, enhances behavioral recovery after brain injury. Thus, the beneficial effects of rehabilitation in promoting recovery after stroke may also depend on BDNF. We tested this hypothesis by evaluating the contribution of BDNF to motor skill relearning after endothelin-1-induced middle cerebral artery occlusion in rats. Antisense BDNF oligonucleotide, which blocks the expression of BDNF (or saline vehicle) was infused into the contralateral lateral ventricle for 28 days after ischemia. Animals received either a graduated rehabilitation program, including running exercise and skilled reaching training, which simulates clinical practice, or no rehabilitation. Functional recovery was assessed with a battery of tests that measured skilled reaching, forelimb use asymmetry, and foraging ability. Rehabilitation significantly improved skilled reaching ability in the staircase task. Antisense BDNF oligonucleotide effectively blocked BDNF mRNA, and negated the beneficial effects of rehabilitation on recovery of skilled reaching. Importantly, antisense BDNF oligonucleotide did not affect reaching with the unaffected limb, body weight, infarct size, or foraging ability, indicating the treatment was specific to relearning of motor skill after ischemia. This study is the first to identify a critical role for BDNF in rehabilitation-induced recovery after stroke, and our results suggest that new treatments to enhance BDNF would constitute a promising therapy for promoting recovery of function after stroke.

Neuroendoscopic Removal of Intraventricular Hemorrhage Combined with Hydrocephalus

The neuroendoscope is playing an increasing role in the diagnosis and treatment of several types of lesions, in particular in the ventricular system. Hydrocephalus associated with intraventricular hemorrhage (IVH) is a good indication for neuroendoscopic surgery. We describe herein our experiences with 17 cases of IVH combined with hydrocephalus treated using a neuroendoscope. The subjects comprised 17 patients with IVH combined with hydrocephalus treated in our department, including cases of thalamic hemorrhage (n=10), caudate hemorrhage (n=5), moya-moya disease (n=1), and dural arteriovenous fistula (n=1). We used a flexible fiberscope that was inserted into the anterior horn of the lateral ventricle. Hematoma was easily evacuated through the working channel of the neuroendoscope by manual maneuvers. Hematomas in the third ventricle, aqueduct and fourth ventricle could also be evacuated. With the addition of septostomy, hematomas in the contralateral lateral ventricle could also be evacuated. All patients underwent successful procedures with good outcomes. No permanent morbidity and mortality was associated with any neuroendoscopic procedures. Shunt insertion was required in 3 cases due to malabsorption of cerebrospinal fluid (CSF) in the chronic stage. Neuroendoscopic procedures with a flexible fiberscope for the removal of IVH allow resolution of the disturbed CSF circulation. This procedure improves the safety and accuracy of treatment for IVH combined with hydrocephalus.

Safety and accuracy of bedside external ventricular drain placement.

To study the safety and accuracy of ventriculostomy by neurosurgical trainees. Initial computed tomographic studies of 346 consecutive patients who underwent bedside ventriculostomy were reviewed retrospectively. Diagnosis, catheter tip location, midline shift, and procedural complications were tabulated. To analyze catheter placement, we used a new grading system: Grade 1, optimal placement in the ipsilateral frontal horn or third ventricle; Grade 2, functional placement in the contralateral lateral ventricle or noneloquent cortex; and Grade 3, suboptimal placement in the eloquent cortex or nontarget cerebrospinal fluid space, with or without functional drainage. Statistical analysis was performed using Fisher's exact test and a weighted kappa coefficient. Diagnoses included the following: subarachnoid hemorrhage, n = 153 (44%); trauma, n = 64 (18%); intracerebral hemorrhage/intraventricular hemorrhage, n = 63 (18%); and other, n = 66 (20%). There were 266 (77%) Grade 1, 34 (10%) Grade 2, and 46 (13%) Grade 3 catheter placements. Hemorrhagic complications occurred in 17 (5%). Four patients (1.2%) were symptomatic, with two (0.6%) requiring surgery. Inter- and intraobserver agreement was almost perfect (kappa = 0.846 and 0.922, respectively) as applied to our grading system. Rates of suboptimal placement were highest in patients with midline shift (P = 0.059) and trauma (P = 0.0001). Rates of optimal placement were highest in patients with subarachnoid hemorrhage (P = 0.003) and when the catheter was placed ipsilateral to the side of midline shift (P = 0.063). Neither the resident's training experience nor the side of placement seemed to affect accuracy. Bedside ventriculostomy is a safe and accurate procedure for intracranial pressure monitoring and cerebrospinal fluid drainage.

SAFETY AND ACCURACY OF BEDSIDE EXTERNAL VENTRICULAR DRAIN PLACEMENT

Abstract Objective: To study the safety and accuracy of ventriculostomy by neurosurgical trainees. Methods: Initial computed tomographic studies of 346 consecutive patients who underwent bedside ventriculostomy were reviewed retrospectively. Diagnosis, catheter tip location, midline shift, and procedural complications were tabulated. To analyze catheter placement, we used a new grading system: Grade 1, optimal placement in the ipsilateral frontal horn or third ventricle; Grade 2, functional placement in the contralateral lateral ventricle or noneloquent cortex; and Grade 3, suboptimal placement in the eloquent cortex or nontarget cerebrospinal fluid space, with or without functional drainage. Statistical analysis was performed using Fisher's exact test and a weighted k coefficient. Results: Diagnoses included the following: subarachnoid hemorrhage, n = 153 (44%); trauma, n = 64 (18%); intracerebral hemorrhage/intraventricular hemorrhage, n = 63 (18%); and other, n = 66 (20%). There were 266 (77%) Grade 1, 34 (10%) Grade 2, and 46 (13%) Grade 3 catheter placements. Hemorrhagic complications occurred in 17 (5%). Four patients (1.2%) were symptomatic, with two (0.6%) requiring surgery. Interand intraobserver agreement was almost perfect (k = 0.846 and 0.922, respectively) as applied to our grading system. Rates of suboptimal placement were highest in patients with midline shift (P = 0.059) and trauma (P = 0.0001). Rates of optimal placement were highest in patients with subarachnoid hemorrhage (P = 0.003) and when the catheter was placed ipsilateral to the side of midline shift (P = 0.063). Neither the resident's training experience nor the side of placement seemed to affect accuracy. Conclusion: Bedside ventriculostomy is a safe and accurate procedure for intracranial pressure monitoring and cerebrospinal fluid drainage.

Neuronal Migration Defect: A Case of Subcortical Heterotopia in a California Sea Lion

A 2 and a half-year-old male California sea lion (Zalophus californianus) presented with a history of intermittent generalized seizures. Magnetic resonance imaging revealed a large focal mass occupying the right cerebral hemisphere with moderate dilatation of the contralateral lateral ventricle. At necropsy, the right cerebral hemispheric white matter was expanded by numerous irregularly shaped, pale pink nodules up to 10 mm in diameter. The overlying cortex was characterized by increased numbers of small, poorly developed gyri with shallow, often indistinct, sulci (polymicrogyria). Microscopically, nodules were composed of neurons, oligodendroglia, microglia, and supporting neuropil and were well delineated from the surrounding white matter. The gross, histological, and immunohistochemical features of this lesion are consistent with a neuronal migration defect resulting in unilateral subcortical heterotopia.

Accuracy of the freehand pass technique for ventriculostomy catheter placement: retrospective assessment using computed tomography scans

The standard method of ventriculostomy catheter placement is a freehand pass technique using surface anatomical landmarks. This study was undertaken to determine the accuracy of successful ventriculostomy procedures performed at a single institution's intensive care unit (ICU). The authors hypothesized that use of surface anatomical landmarks alone with successful results frequently do not correlate with desirable catheter tip placement. Retrospective evaluation was performed on the head computed tomography (CT) scans of 97 patients who underwent 98 freehand pass ventriculostomy catheter placements in an ICU setting. Using the postprocedure CT scans of the patients, 3D measurements were made to calculate the accuracy of ventriculostomy catheter placement. The mean distance (+/- standard deviation [SD]) from the catheter tip to the Monro foramen was 16 +/- 9.6 mm. The mean distance (+/- SD) from the catheter tip to the center of the bur hole was 87.4 +/- 14.0 mm. Regarding accurate catheter tip placement, 56.1% of the catheter tips were in the ipsilateral lateral ventricle, 7.1% were in the contralateral lateral ventricle, 8.2% were in the third ventricle, 6.1% were within the interhemispheric fissure, and 22.4% were within extraventricular spaces. The accuracy of freehand ventriculostomy catheterization at the authors' institution typically required 2 passes per successful placement, and, when successful, was 1.6 cm from the Monro foramen. More importantly, 22.4% of these catheter tips were in nonventricular spaces. Although many neurosurgeons believe that the current practice of ventriculostomy is good enough, the results of this study show that there is certainly much room for improvement.

Intracranial pressure changes during fluid percussion, controlled cortical impact and weight drop injury in rats

In traumatic brain injury research, the fluid percussion injury (FPI) model in the rat is widely used. The injury is graded based on indirect criteria, such as the extracranial pressure wave and/or physiological responses to the injury. We designed this study to investigate if the extracranially monitored pressure in the FPI-device corresponded to the actual intracranial situation. Severe controlled cortical impact (CCI) and severe weight drop injury (WDI) were studied for comparison. We tested the correlation between the extra- and intracranial pressures during severe FPI in rat (2.6-2.9 atm), using pressure probes (diameter 0.34 mm) with high frequency (500 Hz) and high pressure range (1-5 atm). The probes were inserted into either of the lateral ventricles in FPI and in the contralateral lateral ventricle in CCI and WDI to compare the ictal pressure pulses between the models. FPI showed a time lag between the extracranial, intracranial ipsilateral and intracranial contralateral pressure curves respectively, reflecting the different distances between the pressure source and the individual pressure probes. There was a high degree of correlation (r = 0.994, p<0.0001) between the extra- and intracranial pressure pulses, once corrected for the time lag. We found no significant differences between the extracranial and the intracranial peak pressure in either ventricle in FPI. In CCI and WDI the contralateral pressure pulses were significantly smaller than in FPI. CCI resulted in higher pressure peaks than WDI, due to higher impact velocity. The extracranial pressure pulse appears to be a good estimate of the intraventricular pressure pulse generated during FPI. Severe CCI and WDI generated intraventricular pressure pulses of much lower magnitude than FPI, explaining the lesser degree of brain stem involvement in the former models.

The isolated lateral ventricle. Experience at the hospital for sick children

Isolation of the lateral ventricle has long been known to occur following ventriculitis. However, in recent years, functional isolation of the lateral ventricle has been seen with increasing frequency. Since 1979, eight patients without evidence of infection have required treatment for an isolated lateral ventricle following insertion of a contralateral ventriculoperitoneal shunt at the Hospital for Sick Children, Toronto, Ontario, Canada. Two of these patients developed their hydrocephalus after intraventricular hemorrhage, and in six patients the hydrocephalus was associated with myelodysplasia. We specifically excluded patients in whom isolation of the lateral ventricle was secondary to ventriculitis. We feel that the isolated lateral ventricle following ventriculoperitoneal shunting may be due to a dynamic situation where overdrainage of the shunted ventricle leads to a functional obliteration of the foramen of Monro and subsequent enlargement of the contralateral lateral ventricle.

Intraventricular aneurysm of the medial posterior choroid artery clipped via the contralateral transcallosal approach.

In lesions located in the lateral ventricle of the dominant hemisphere the contralateral transcallosal approach provides maximum protection of the dominant side as well as excellent visualization of the cella media of the contralateral lateral ventricle. We demonstrated this safe approach in a rare case with intraventricular aneurysm of the left medial choroid artery. The literature on aneurysms in the lateral ventricle is discussed.

Contralateral ventricular dilatation in supratentorial tumors.

The computerized tomographic (CT) scans of 411 patients with supratentorial lateralized tumors were compared with an assessment of their clinical condition. More than one-third of these patients showed dilatation of the contralateral lateral ventricle, which was associated with a lower level of consciousness.

Computed tomography of extracerebral hematoma

The appearance on C.T. of 30 extracerebral hematomas is described. Acute subdural hematomas were seen as bandlike lesions with markedly increased, homogenous density. Epidural hematomas demonstrated a high density and a biconvex, lenticular shape. During the process of liquefaction the density decreases and three hematomas appeared as isodense lesions. The majority of chronic subdural hematomas presented a mildly to moderately decreased, nonhomogenous density, the clearly identifiable inner wall of the lesion being either convex or concave. Subdural hygromas showed a homogeneous, markedly decreased density. Almost all the hematomas caused compression of the homolateral lateral ventricle and displacement of midline structures, particularly of the septum pellucidum. In 60% of the hematomas a dilatation of the contralateral lateral ventricle, predominantly of the posterior part was seen. Acute hematomas presented oedema in varying degrees, in chronic hematomas oedema was usually absent. In the original interpretation extracerebral hematomas were recognized as a lesion on C.T. in 97% (1 false negative result), in 90%, the lesion was correctly diagnosed as an extracerebral hematoma (1 false negative and 2 incorrect). The series contained one false positive C.T. scan and 2 intracerebral hematomas were interpreted incorrectly as subdural hematomas. The review C.T. diagnosis proved to be correct in 100%. C.T. and angiography appeared to have about the same diagnostic accuracy. However, C.T. is a non invasive investigation and it provides valuable additional information with regard to all the intracranial contents. Therefore C.T. should be the method of first choice in the diagnosis of extracerebral hematomas.