Two Hundred Thirty-Six Children With Developmental Hydrocephalus: Causes and Clinical Consequences

Few systematic assessments of developmental forms of hydrocephalus exist. We reviewed magnetic resonance images (MRIs) and clinical records of patients with infancy-onset hydrocephalus. Among 411 infants, 236 had hydrocephalus with no recognizable extrinsic cause. These children were assigned to 1 of 5 subtypes and compared on the basis of clinical characteristics and developmental and surgical outcomes. At an average age of 5.3 years, 72% of children were walking independently and 87% could eat by mouth; in addition, 18% had epilepsy. Distinct patterns of associated malformations and syndromes were observed within each subtype. On average, children with aqueductal obstruction, cysts, and encephaloceles had worse clinical outcomes than those with other forms of developmental hydrocephalus. Overall, 53% of surgically treated patients experienced at least 1 shunt failure, but hydrocephalus associated with posterior fossa crowding required fewer shunt revisions. We conclude that each subtype of developmental hydrocephalus is associated with distinct clinical characteristics, syndromology, and outcomes, suggesting differences in underlying mechanisms.

Ultrasound stylet for non-image-guided ventricular catheterization

OBJECT Urgent ventriculostomy placement can be a lifesaving procedure in the setting of hydrocephalus or elevated intracranial pressure. While external ventricular drain (EVD) insertion is common, there remains a high rate of suboptimal drain placement. Here, the authors seek to demonstrate the feasibility of an ultrasound-based guidance system that can be inserted into an existing EVD catheter to provide a linear ultrasound trace that guides the user toward the ventricle. METHODS The ultrasound stylet was constructed as a thin metal tube, with dimensions equivalent to standard catheter stylets, bearing a single-element, ceramic ultrasound transducer at the tip. Ultrasound backscatter signals from the porcine ventricle were processed by custom electronics to offer real-time information about ventricular location relative to the catheter. Data collected from the prototype device were compared with reference measurements obtained using standard clinical ultrasound imaging. RESULTS A study of porcine ventricular catheterization using the experimental device yielded a high rate of successful catheter placement after a single pass (10 of 12 trials), despite the small size of pig ventricles and the lack of prior instruction on porcine ventricular architecture. A characteristic double-peak signal was identified, which originated from ultrasound reflections off of the near and far ventricular walls. Ventricular dimensions, as obtained from the width between peaks, were in agreement with standard ultrasound reference measurements (p < 0.05). Furthermore, linear ultrasound backscatter data permitted in situ measurement of the stylet distance to the ventricular wall (p < 0.05), which assisted in catheter guidance. CONCLUSIONS The authors have demonstrated the ability of the prototype ultrasound stylet to guide ventricular access in the porcine brain. The alternative design of the device makes it potentially easy to integrate into the standard workflow for bedside EVD placement. The availability of a fast, easy-to-use, inexpensive guidance system can play a role in reducing the complication rate for EVD placement.

Initial clinical presentation of children with acute and chronic versus acute subdural hemorrhage resulting from abusive head trauma

OBJECT At presentation, children who have experienced abusive head trauma (AHT) often have subdural hemorrhage (SDH) that is acute, chronic, or both. Controversy exists whether the acute SDH associated with chronic SDH results from trauma or from spontaneous rebleeding. The authors compared the clinical presentations of children with AHT and acute SDH with those having acute and chronic SDH (acute/chronic SDH). METHODS The study was a multicenter retrospective review of children who had experienced AHT during 2004-2009. The authors compared the clinical and radiological characteristics of children with acute SDH to those of children with acute/chronic SDH. RESULTS The study included 383 children with AHT and either acute SDH (n = 291) or acute/chronic SDH (n = 92). The children with acute/chronic SDH were younger, had higher initial Glasgow Coma Scale scores, fewer deaths, fewer skull fractures, less parenchymal brain injury, and fewer acute noncranial fractures than did children with acute SDH. No between-group differences were found for the proportion with retinal hemorrhages, healing noncranial fractures, or acute abusive bruises. A similar proportion (approximately 80%) of children with acute/chronic SDH and with acute SDH had retinal hemorrhages or acute or healing extracranial injures. Of children with acute/chronic SDH, 20% were neurologically asymptomatic at presentation; almost half of these children were seen for macrocephaly, and for all of them, the acute SDH was completely within the area of the chronic SDH. CONCLUSIONS Overall, the presenting clinical and radiological characteristics of children with acute SDH and acute/chronic SDH caused by AHT did not differ, suggesting that repeated abuse, rather than spontaneous rebleeding, is the etiology of most acute SDH in children with chronic SDH. However, more severe neurological symptoms were more common among children with acute SDH. Children with acute/chronic SDH and asymptomatic macrocephaly have unique risks and distinct radiological and clinical characteristics.

An update on research priorities in hydrocephalus: overview of the third National Institutes of Health-sponsored symposium "Opportunities for Hydrocephalus Research: Pathways to Better Outcomes"

Building on previous National Institutes of Health-sponsored symposia on hydrocephalus research, "Opportunities for Hydrocephalus Research: Pathways to Better Outcomes" was held in Seattle, Washington, July 9-11, 2012. Plenary sessions were organized into four major themes, each with two subtopics: Causes of Hydrocephalus (Genetics and Pathophysiological Modifications); Diagnosis of Hydrocephalus (Biomarkers and Neuroimaging); Treatment of Hydrocephalus (Bioengineering Advances and Surgical Treatments); and Outcome in Hydrocephalus (Neuropsychological and Neurological). International experts gave plenary talks, and extensive group discussions were held for each of the major themes. The conference emphasized patient-centered care and translational research, with the main objective to arrive at a consensus on priorities in hydrocephalus that have the potential to impact patient care in the next 5 years. The current state of hydrocephalus research and treatment was presented, and the following priorities for research were recommended for each theme. 1) Causes of Hydrocephalus-CSF absorption, production, and related drug therapies; pathogenesis of human hydrocephalus; improved animal and in vitro models of hydrocephalus; developmental and macromolecular transport mechanisms; biomechanical changes in hydrocephalus; and age-dependent mechanisms in the development of hydrocephalus. 2) Diagnosis of Hydrocephalus-implementation of a standardized set of protocols and a shared repository of technical information; prospective studies of multimodal techniques including MRI and CSF biomarkers to test potential pharmacological treatments; and quantitative and cost-effective CSF assessment techniques. 3) Treatment of Hydrocephalus-improved bioengineering efforts to reduce proximal catheter and overall shunt failure; external or implantable diagnostics and support for the biological infrastructure research that informs these efforts; and evidence-based surgical standardization with longitudinal metrics to validate or refute implemented practices, procedures, or tests. 4) Outcome in Hydrocephalus-development of specific, reliable batteries with metrics focused on the hydrocephalic patient; measurements of neurocognitive outcome and quality-of-life measures that are adaptable, trackable across the growth spectrum, and applicable cross-culturally; development of comparison metrics against normal aging and sensitive screening tools to diagnose idiopathic normal pressure hydrocephalus against appropriate normative age-based data; better understanding of the incidence and prevalence of hydrocephalus within both pediatric and adult populations; and comparisons of aging patterns in adults with hydrocephalus against normal aging patterns.

Endoscopic third ventriculostomy and choroid plexus cauterization in infants with hydrocephalus: a retrospective Hydrocephalus Clinical Research Network study

OBJECT

The use of endoscopic third ventriculostomy (ETV) with choroid plexus cauterization (CPC) has been advocated as an alternative to CSF shunting in infants with hydrocephalus. There are limited reports of this procedure in the North American population, however. The authors provide a retrospective review of the experience with combined ETV + CPC within the North American Hydrocephalus Clinical Research Network (HCRN).

METHODS

All children (< 2 years old) who underwent an ETV + CPC at one of 7 HCRN centers before November 2012 were included. Data were collected retrospectively through review of hospital records and the HCRN registry. Comparisons were made to a contemporaneous cohort of 758 children who received their first shunt at < 2 years of age within the HCRN.

RESULTS

Thirty-six patients with ETV + CPC were included (13 with previous shunt). The etiologies of hydrocephalus were as follows: intraventricular hemorrhage of prematurity (9 patients), aqueductal stenosis (8), myelomeningocele (4), and other (15). There were no major intraoperative or early postoperative complications. There were 2 postoperative CSF infections. There were 2 deaths unrelated to hydrocephalus and 1 death from seizure. In 18 patients ETV + CPC failed at a median time of 30 days after surgery (range 4-484 days). The actuarial 3-, 6-, and 12-month success for ETV + CPC was 58%, 52%, and 52%. Time to treatment failure was slightly worse for the 36 patients with ETV + CPC compared with the 758 infants treated with shunts (p = 0.012). Near-complete CPC (≥ 90%) was achieved in 11 cases (31%) overall, but in 50% (10 of 20 cases) in 2012 versus 6% (1 of 16 cases) before 2012 (p = 0.009). Failure was higher in children with < 90% CPC (HR 4.39, 95% CI 0.999-19.2, p = 0.0501).

CONCLUSIONS

The early North American multicenter experience with ETV + CPC in infants demonstrates that the procedure has reasonable safety in selected cases. The degree of CPC achieved might be associated with a surgeon's learning curve and appears to affect success, suggesting that surgeon training might improve results.

Role of dorsal rhizotomy in spinal cord injury-induced spasticity

Selective dorsal rhizotomy may have a role in the management of spinal cord injury (SCI)-induced spasticity. Spasticity and spasms are common sequelae of SCI in children. Depending on the clinical scenario, treatments may include physical and occupational therapy, oral medications, chemodenervation, and neurosurgical interventions. Selective dorsal rhizotomy (SDR) is used in the management of spasticity in selected children with cerebral palsy, but, to the authors' knowledge, its use has not been reported in children with SCI. The authors describe the cases of 3 pediatric patients with SCI and associated spasticity treated with SDR. Two of the 3 patients have had significant long-term improvement in their preoperative spasticity. Although the third patient also experienced initial relief, his spasticity quickly returned to its preoperative severity, necessitating additional therapies. Selective dorsal rhizotomy may have a place in the treatment of selected children with spasticity due to SCI.

Risk factors for first cerebrospinal fluid shunt infection: findings from a multi-center prospective cohort study

OBJECTIVE

To quantify the extent to which cerebrospinal fluid (CSF) shunt revisions are associated with increased risk of CSF shunt infection, after adjusting for patient factors that may contribute to infection risk.

STUDY DESIGN

We used the Hydrocephalus Clinical Research Network registry to assemble a large prospective 6-center cohort of 1036 children undergoing initial CSF shunt placement between April 2008 and January 2012. The primary outcome of interest was first CSF shunt infection. Data for initial CSF shunt placement and all subsequent CSF shunt revisions prior to first CSF shunt infection, where applicable, were obtained. The risk of first infection was estimated using a multivariable Cox proportional hazard model accounting for patient characteristics and CSF shunt revisions, and is reported using hazard ratios (HRs) with 95% CI.

RESULTS

Of the 102 children who developed first infection within 12 months of placement, 33 (32%) followed one or more CSF shunt revisions. Baseline factors independently associated with risk of first infection included: gastrostomy tube (HR 2.0, 95% CI, 1.1, 3.3), age 6-12 months (HR 0.3, 95% CI, 0.1, 0.8), and prior neurosurgery (HR 0.4, 95% CI, 0.2, 0.9). After controlling for baseline factors, infection risk was most significantly associated with the need for revision (1 revision vs none, HR 3.9, 95% CI, 2.2, 6.5; ≥2 revisions, HR 13.0, 95% CI, 6.5, 24.9).

CONCLUSIONS

This study quantifies the elevated risk of infection associated with shunt revisions observed in clinical practice. To reduce risk of infection risk, further work should optimize revision procedures.

Evaluation of microbial bacterial and fungal diversity in cerebrospinal fluid shunt infection

Background

Cerebrospinal fluid shunt infection can be recalcitrant. Recurrence is common despite appropriate therapy for the pathogens identified by culture. Improved diagnostic and therapeutic approaches are required, and culture-independent molecular approaches to cerebrospinal fluid shunt infections have not been described.

Objectives

To identify the bacteria and fungi present in cerebrospinal fluid from children with cerebrospinal fluid shunt infection using a high-throughput sequencing approach, and to compare those results to those from negative controls and conventional culture.

Methods

This descriptive study included eight children ≤18 years old undergoing treatment for culture-identified cerebrospinal fluid shunt infection. After routine aerobic culture of each cerebrospinal fluid sample, deoxyribonucleic acid (DNA) extraction was followed by amplification of the bacterial 16S rRNA gene and the fungal ITS DNA region tag-encoded FLX-Titanium amplicon pyrosequencing and microbial phylogenetic analysis.

Results

The microbiota analyses for the initial cerebrospinal fluid samples from all eight infections identified a variety of bacteria and fungi, many of which did not grow in conventional culture. Detection by conventional culture did not predict the relative abundance of an organism by pyrosequencing, but in all cases, at least one bacterial taxon was detected by both conventional culture and pyrosequencing. Individual bacterial species fluctuated in relative abundance but remained above the limits of detection during infection treatment.

Conclusions

Numerous bacterial and fungal organisms were detected in these cerebrospinal fluid shunt infections, even during and after treatment, indicating diverse and recalcitrant shunt microbiota. In evaluating cerebrospinal fluid shunt infection, fungal and anaerobic bacterial cultures should be considered in addition to aerobic bacterial cultures, and culture-independent approaches offer a promising alternative diagnostic approach. More effective treatment of cerebrospinal fluid shunt infections is needed to reduce unacceptably high rates of reinfection, and this work suggests that one effective strategy may be reduction of the diverse microbiota present in infection.

Diffusion tensor imaging of the superior cerebellar peduncle identifies patients with posterior fossa syndrome

INTRODUCTION

Posterior fossa tumors are the most common brain tumor of children. Aggressive resection correlates with long-term survival. A high incidence of posterior fossa syndrome (PFS), impairing the quality of life in many survivors, has been attributed to damage to bilateral dentate nucleus or to cerebellar output pathways. Using diffusion tensor imaging (DTI), we examined the involvement of the dentothalamic tracts, specifically the superior cerebellar peduncle (SCP), in patients with posterior fossa tumors and the association with PFS.

METHODS

DTI studies were performed postoperatively in patients with midline (n = 12), lateral cerebellar tumors (n = 4), and controls. The location and visibility of the SCP were determined. The postoperative course was recorded, especially with regard to PFS, cranial nerve deficits, and oculomotor function.

RESULTS

The SCP travels immediately adjacent to the lateral wall of the fourth ventricle and just medial to the middle cerebellar peduncle. Patients with midline tumors that still had observable SCP did not develop posterior fossa syndrome (N = 7). SCPs were absent, on either preoperative (N = 1, no postoperative study available) or postoperative studies (N = 4), in the five patients who developed PFS. Oculomotor deficits of tracking were observed in patients independent of PFS or SCP involvement.

CONCLUSION

PFS can occur with bilateral injury to the outflow from dentate nuclei. In children with PFS, this may occur due to bilateral injury to the superior cerebellar peduncle. These tracts sit immediately adjacent to the wall of the ventricle and are highly vulnerable when an aggressive resection for these tumors is performed.

Low-dose head computed tomography in children: a single institutional experience in pediatric radiation risk reduction: clinical article

OBJECT

In this study, the authors describe their experience with a low-dose head CT protocol for a preselected neurosurgical population at a dedicated pediatric hospital (Seattle Children's Hospital), the largest number of patients with this protocol reported to date.

METHODS

All low-dose head CT scans between October 2011 and November 2012 were reviewed. Two different low-dose radiation dosages were used, at one-half or one-quarter the dose of a standard head CT scan, based on patient characteristics agreed upon by the neurosurgery and radiology departments. Patient information was also recorded, including diagnosis and indication for CT scan.

RESULTS

Six hundred twenty-four low-dose head CT procedures were performed within the 12-month study period. Although indications for the CT scans varied, the most common reason was to evaluate the ventricles and catheter placement in hydrocephalic patients with shunts (70%), followed by postoperative craniosynostosis imaging (12%). These scans provided adequate diagnostic imaging, and no patient required a follow-up full-dose CT scan as a result of poor image quality on a low-dose CT scan. Overall physician comfort and satisfaction with interpretation of the images was high. An additional 2150 full-dose head CT scans were performed during the same 12-month time period, making the total number of CT scans 2774. This value compares to 3730 full-dose head CT scans obtained during the year prior to the study when low-dose CT and rapid-sequence MRI was not a reliable option at Seattle Children's Hospital. Thus, over a 1-year period, 22% of the total CT scans were able to be converted to low-dose scans, and full-dose CT scans were able to be reduced by 42%.

CONCLUSIONS

The implementation of a low-dose head CT protocol substantially reduced the amount of ionizing radiation exposure in a preselected population of pediatric neurosurgical patients. Image quality and diagnostic utility were not significantly compromised.

Outcomes of CSF shunting in children: comparison of Hydrocephalus Clinical Research Network cohort with historical controls: clinical article

OBJECT

The Hydrocephalus Clinical Research Network (HCRN), which comprises 7 pediatric neurosurgical centers in North America, provides a unique multicenter assessment of the current outcomes of CSF shunting in nonselected patients. The authors present the initial results for this cohort and compare them with results from prospective multicenter trials performed in the 1990s.

METHODS

Analysis was restricted to patients with newly diagnosed hydrocephalus undergoing shunting for the first time. Detailed perioperative data from 2008 through 2012 for all HCRN centers were prospectively collected and centrally stored by trained research coordinators. Historical control data were obtained from the Shunt Design Trial (1993-1995) and the Endoscopic Shunt Insertion Trial (1996-1999). The primary outcome was time to first shunt failure, which was determined by using Cox regression survival analysis.

RESULTS

Mean age of the 1184 patients in the HCRN cohort was older than mean age of the 720 patients in the historical cohort (2.51 years vs 1.60 years, p < 0.0001). The distribution of etiologies differed (p < 0.0001, chi-square test); more tumors and fewer myelomeningoceles caused the hydrocephalus in the HCRN cohort patients. The hazard ratio for first shunt failure significantly favored the HCRN cohort, even after the model was adjusted for the prognostic effects of age and etiology (adjusted HR 0.82, 95% CI 0.69-0.96).

CONCLUSIONS

Current outcomes of shunting in general pediatric neurosurgery practice have improved over those from the 1990s, although the reasons remain unclear.

New and improved ways to treat hydrocephalus: Pursuit of a smart shunt

The most common treatment for hydrocephalus is placement of a cerebrospinal fluid shunt to supplement or replace lost drainage capacity. Shunts are life-saving devices but are notorious for high failure rates, difficulty of diagnosing failure, and limited control options. Shunt designs have changed little since their introduction in 1950s, and the few changes introduced have had little to no impact on these long-standing problems. For decades, the community has envisioned a “smart shunt” that could provide advanced control, diagnostics, and communication based on implanted sensors, feedback control, and telemetry. The most emphasized contribution of smart shunts is the potential for advanced control algorithms, such as weaning from shunt dependency and personalized control. With sensor-based control comes the opportunity to provide data to the physician on patient condition and shunt function, perhaps even by a smart phone. An often ignored but highly valuable contribution would be designs that correct the high failure rates of existing shunts. Despite the long history and increasing development activity in the past decade, patients are yet to see a commercialized smart shunt. Most smart shunt development focuses on concepts or on isolated technical features, but successful smart shunt designs will be a balance between technical feasibility, economic viability, and acceptable regulatory risk. Here, we present the status of this effort and a framework for understanding the challenges and opportunities that will guide introduction of smart shunts into patient care.

The assessment of bulging fontanel and splitting of sutures in premature infants: an interrater reliability study by the Hydrocephalus Clinical Research Network

OBJECT

Previous studies from the Hydrocephalus Clinical Research Network (HCRN) have shown a great degree of variation in surgical decision making for infants with posthemorrhagic hydrocephalus, such as when to temporize, when to shunt, or when to convert. Since much of this clinical decision making is dictated by clinical signs of increased intracranial pressure (including bulging fontanel and splitting of sutures), the authors investigated whether there was variability in how these signs were being assessed by neurosurgeons. They wanted to answer the following question: is there acceptable interrater reliability in the neurosurgical assessment of bulging fontanel and split sutures?

METHODS

Explicit written definitions of "bulging fontanel" and "split sutures" were agreed upon with consensus across the HCRN. At 5 HCRN centers, pairs of neurosurgeons independently assessed premature infants in the first 3 months of life for the presence of a split suture and/or bulging fontanel, according to the a priori definitions. Interrater reliability was then calculated between pairs of observers using the Cohen simple kappa coefficient. Institutional board review approval was obtained at each center and at the University of Utah Data Coordinating Center.

RESULTS

A total of 38 infants were assessed by 13 different raters (10 faculty, 2 fellows, and 1 resident). The kappa for bulging fontanel was 0.65 (95% CI 0.41-0.90), and the kappa for split sutures was 0.84 (95% CI 0.66-1.0). No complications from the study were encountered.

CONCLUSIONS

The authors have found a high degree of interrater reliability among neurosurgeons in their assessment of bulging fontanel and split sutures. While decision making may vary, the clinical assessment of this cohort appears to be consistent among these physicians, which is crucial for prospective studies moving forward.

Rapid sequence magnetic resonance imaging in the assessment of children with hydrocephalus

OBJECTIVE

Recent reports have shown the utility of rapid-acquisition magnetic resonance imaging (MRI) in the evaluation of children with hydrocephalus. Rapid sequence MRI (RS-MRI) acquires clinically useful images in seconds without exposing children to the risks of ionizing radiation or sedation. We review our experience with RS-MRI in children with shunts.

METHODS

Overall image quality, cost, catheter visualization, motion artifact, and ventricular size were reviewed for all RS-MRI studies obtained at Seattle Children's Hospital during a 2-year period. Image acquisition time was 12-19 seconds, with sessions usually lasting less than 3 minutes.

RESULTS

Image quality was very good or excellent in 94% of studies, whereas only one was graded as poor. Significant motion artifact was noted in 7%, whereas 77% had little or no motion artifact. Catheter visualization was good or excellent in 57%, poor in 36%, and misleading in 7%. Small ventricular size was correlated with poor catheter visualization (Spearman's ρ = 0.586; P < 0.00001). RS-MRI imaging cost ∼$650 more than conventional computed tomography (CT).

CONCLUSIONS

Our study supports that RS-MRI is an adequate substitute that allows reduced use of CT imaging and resultant exposure to ionizing radiation. Catheter position visualization remains suboptimal when ventricles are small, but shunt malfunction can be adequately determined in most cases. The cost is significantly more than CT, but the potential for lifetime reduction in radiation exposure may justify this expense in children. Limitations include the risk of valve malfunction after repeated exposure to high magnetic fields and the need for reprogramming with many types of adjustable valves.

Image-guided cerebrospinal fluid shunting in children: catheter accuracy and shunt survival

OBJECT

Cerebrospinal fluid shunt placement has a high failure rate, especially in patients with small ventricles. Frameless stereotactic electromagnetic image guidance can assist ventricular catheter placement. The authors studied the effects of image guidance on catheter accuracy and shunt survival in children.

METHODS

Pediatric patients who underwent placement or revision of a frontal ventricular CSF shunt were retrospectively evaluated. Catheters were placed using either anatomical landmarks or image guidance. Preoperative ventricular size and postoperative catheter accuracy were quantified. Outcomes of standard and image-guided groups were compared.

RESULTS

Eighty-nine patients underwent 102 shunt surgeries (58 initial, 44 revision). Image guidance was used in the placement of 56 shunts and the standard technique in 46. Shunt failure rates were not significantly different between the standard (22%) and image-guided (25%) techniques (p = 0.21, log-rank test). Ventricular size was significantly smaller in patients in the image-guided group (p < 0.02, Student t-test) and in the surgery revision group (p < 0.01). Small ventricular size did not affect shunt failure rate, even when controlling for shunt insertion technique. Despite smaller average ventricular size, the accuracy of catheter placement was significantly improved with image guidance (p < 0.01). Shunt accuracy did not affect shunt survival.

CONCLUSIONS

The use of image guidance improved catheter tip accuracy compared with a standard technique, despite smaller ventricular size. Failure rates were not dependent on shunt insertion technique, but an observed selection bias toward using image guidance for more at-risk catheter placements showed failure rates similar to initial surgeries.

Center effect and other factors influencing temporization and shunting of cerebrospinal fluid in preterm infants with intraventricular hemorrhage

OBJECT

There is little consensus regarding the indications for surgical CSF diversion (either with implanted temporizing devices [reservoir or subgaleal shunt] or shunt alone) in preterm infants with posthemorrhagic hydrocephalus. The authors determined clinical and neuroimaging factors associated with the use of surgical CSF diversion among neonates with intraventricular hemorrhage (IVH), and describe variations in practice patterns across 4 large pediatric centers.

METHODS

The use of implanted temporizing devices and conversion to permanent shunts was examined in a consecutive sample of 110 neonates surgically treated for IVH related to prematurity from the 4 clinical centers of the Hydrocephalus Clinical Research Network (HCRN). Clinical, neuroimaging, and so-called processes of care factors were analyzed.

RESULTS

Seventy-three (66%) of the patients underwent temporization procedures, including 50 ventricular reservoir and 23 subgaleal shunt placements. Center (p < 0.001), increasing ventricular size (p = 0.04), and bradycardia (p = 0.07) were associated with the use of an implanted temporizing device, whereas apnea, occipitofrontal circumference (OFC), and fontanel assessments were not. Implanted temporizing devices were converted to permanent shunts in 65 (89%) of the 73 neonates. Only a full fontanel (p < 0.001) and increased ventricular size (p = 0.002) were associated with conversion of the temporizing devices to permanent shunts, whereas center, OFCs, and clot characteristics were not.

CONCLUSIONS

Considerable center variability exists in neurosurgical approaches to temporization of IVH in prematurity within the HCRN; however, variation between centers is not seen with permanent shunting. Increasing ventricular size-rather than classic clinical findings such as increasing OFCs-represents the threshold for either temporization or shunting of CSF.

Intracerebral Abscess Associated With the Camino Intracranial Pressure Monitor: Case Report and Review of the Literature

BACKGROUND AND IMPORTANCE:

Intracranial pressure (ICP) monitoring is a mainstay in the management of traumatic brain injury. Large investigations have validated the safety and efficacy of ICP monitors in comatose patients. Clinically relevant infections are extremely rare and cerebral abscess has never been reported with the Camino device. We describe an exceptional case of a life-threatening intracerebral abscess from an intraparenchymal ICP monitor.

CLINICAL PRESENTATION:

A 35-month-old child required 7 days of ICP monitoring after a fall from a 2-story window. His hospital course was complicated by severe airway edema treated, in part, with high-dose corticosteroid therapy for a total of 10 days. Two weeks later, the patient deteriorated acutely owing to a large intracerebral abscess under the previous ICP monitor site. Urgent craniotomy with evacuation of the abscess was performed on 2 separate occasions. Cultures grew methicillin-sensitive Staphylococcus aureus, which was treated with long-term antibiotics. At the 3-month follow-up, the patient was meeting age-appropriate milestones without focal deficits.

CONCLUSION:

To the best of our knowledge, this is the first report describing an intracerebral abscess as a complication from an intraparenchymal pressure monitor. Corticosteroid therapy may have constituted an independent risk factor for the ICP monitor--associated infection, as well as reinsertion of the ICP monitoring device at the same site. That this is the first reported parenchymal infectious complication underscores the safety of this device with respect to infection. When reinsertion of a parenchymal monitor is considered, a new site should be chosen.

Brainstem hypertrophy, acquired Chiari malformation, syringomyelia, and hydrocephalus: diagnostic dilemma

This 18-year-old woman presented with symptoms of right upper-extremity ataxia and imaging evidence of syringomyelia and an acquired Chiari malformation after a previous suboccipital decompression for cerebellar hemorrhage. The patient underwent posterior fossa reexploration to detether any adhesions and release scar tissue in the fourth ventricular outlet. Her symptoms of syringomyelia resolved but she then developed symptoms of lethargy, confusion, and amnesia in addition to ataxia. Repeat neural axis imaging revealed resolution of the syrinx but prominent brainstem hypertrophy. Eventually, the placement of a ventriculoperitoneal shunt resulted in the resolution of both symptoms and brainstem hypertrophy. In the present article, the authors elaborate on this first reported case of a reversible brainstem hypertrophy responsive to CSF shunting.

Use of the ETV Success Score to explain the variation in reported endoscopic third ventriculostomy success rates among published case series of childhood hydrocephalus

OBJECT

Published case series of endoscopic third ventriculostomy (ETV) for childhood hydrocephalus have reported widely varying success rates. The authors recently developed and internally validated the ETV Success Score (ETVSS); this is a simplified means of predicting the 6-month success rate of ETV for a child with hydrocephalus, based on age, etiology of hydrocephalus, and presence of a previous shunt. The authors hypothesized that the ETVSS would be able to predict with reasonable accuracy the actual ETV success rate reported among published case series.

METHODS

A literature search was performed to identify published pediatric ETV papers that contained enough information with which to calculate an aggregate, mean predicted ETVSS for the cohort. This was then compared with the actual ETV success rate in the cohort. Data were extracted independently in triplicate, including by 2 individuals who were not involved with the development of the ETVSS.

RESULTS

Fifteen papers reporting on 322 patients were included. Interrater reliability was very high in determining the predicted ETVSS (intraclass correlation coefficient 0.99). The predicted ETVSS for each paper agreed strongly with the actual ETV success rate reported in each paper (reliability intraclass correlation coefficient 0.81). There was no significant difference in the magnitude of the predicted ETVSS and the actual ETV success (p = 0.98, paired t-test). In a linear regression model, the predicted ETVSS explained 62% of the variation in actual ETV success. When the entire cohort was combined and analyzed together, the overall mean predicted ETVSS was 57.9%, which was nearly identical to the actual ETV success rate of 59.2%.

CONCLUSIONS

The ETVSS closely predicts the actual ETV success rate reported in selected papers published over the last 20 years and explains much of the variation.

Functional magnetic resonance imaging for presurgical evaluation of very young pediatric patients with epilepsy

OBJECT

The authors describe their experience with functional MR (fMR) imaging in children as young as 5 years of age, or even younger in developmental age equivalent. Functional MR imaging can be useful for identifying eloquent cortex prior to surgical intervention. Most fMR imaging clinical work has been done in adults, and although children as young as 8 years of age have been included in larger clinical series, cases in younger children are rarely reported.

METHODS

The authors reviewed presurgical fMR images in eight patients who were 8 years of age or younger, six of whom were 5 or 6 years of age. Each patient had undergone neuropsychological testing. Three patients functioned at a below-average level, with adaptive functioning age scores of 3 to 4 years. Self-paced finger tapping (with passive movement in one patient) and silent language tasks were used as activation tasks. The language task was modified for younger children, for whom the same (not novel) stimuli were used for extensive practice ahead of time and in the MR imaging unit. Patient preparation involved techniques such as having experienced staff present to work with patients and providing external management during imaging. Six of eight patients had extensive training and practice prior to the procedure. In the two youngest patients, this training included use of a mock MR unit.

RESULTS

All cases yielded successful imaging. Finger tapping in all seven of the patients who could perform it demonstrated focal motor activation in the frontal-parietal region, with expected activation elsewhere, including in the cerebellum. Three of four patients had the expected verb generation task activations, with left-hemisphere dominance, including a 6-year-old child who functioned at the 3-year, 9-month level. The only child (an 8-year-old) who was not prepared prior to the imaging session for the verb generation task failed this task due to movement artifact.

CONCLUSIONS

Despite the challenges of successfully using fMR imaging in very young and clinically involved patients, these studies can be performed successfully in children with a chronological age of 5 or 6 years and a developmental age as young as 3 or 4 years.

Multidrug-resistant Enterococcus faecium meningitis in a toddler: characterization of the organism and successful treatment with intraventricular daptomycin and intravenous tigecycline

A case of enterococcal meningitis in a toddler is presented. The organism was highly resistant to all drugs previously used for pediatric Gram-positive meningitis. She was successfully treated with intraventricular and intravenous daptomycin and intravenous tigecycline. The organism was characterized as a member of CC17, a notorious emerging nosocomial clone of Enterococcus faecium.

An intracranial aneurysm and dural arteriovenous fistula in a newborn

The authors present the case of a newborn with an intracerebral aneurysm and a dural arteriovenous fistula. The patient initially presented with intraventricular hemorrhage and hydrocephalus, with evidence of remote subarachnoid hemorrhage, left hemispheric stroke, and sagittal sinus thrombosis. He was treated with a ventriculoperitoneal shunt and subsequent staged endovascular obliteration of both the aneurysm and fistula. Interestingly, the aneurysm did not appear on an artery feeding the abnormal fistula. Intracerebral aneurysms in the neonatal population are rare, and dural arteriovenous fistulae even more so; we present a case of a 2-month-old infant with both, as well as a review of the literature concerning these rare vascular abnormalities.

The posterior petrosal approach: technique and applications in pediatric neurosurgery

OBJECT

Various lesions occur in deep locations or at the skull base in pediatric patients and require skull base approaches for resection. Skull base surgery confers the advantages of improved line of sight, a wider operative corridor, and reduced brain retraction. The posterior petrosal approach provides simultaneous access to lesions in the posterior middle fossa and posterior fossa from the top of the clivus to the level of the jugular foramen. It allows visualization of the ventrolateral brainstem and may be combined with various other supra- and infratentorial approaches, thus giving the surgeon a wide array of access routes to the lesion.

METHODS

The authors conducted a retrospective review of all cases involving pediatric patients undergoing a posterior petrosal approach, either alone or in combination with other cranial approaches. Preoperative and postoperative data were collected, including presentation, neurological examination, imaging findings, pathological condition, operative details, perioperative complications, and postoperative outcomes.

RESULTS

There were 13 patients (6 female, 7 male) with a mean age of 12.6 years (range 14 months-9 years). The posterior petrosal was the sole skull base cranial approach in 4 patients, whereas the posterior petrosal was combined with 1 or more other cranial approaches in 9. A gross-total resection was achieved in 7 patients, subtotal resection in 5, and a biopsy was performed in 1. Complications occurred in 9 patients, including 7 new or worsened cranial neuropathies. There was no perioperative mortality.

CONCLUSIONS

Although infrequently used in pediatric neurosurgery, the posterior petrosal approach is a highly versatile approach that can access intra- and extraaxial pathology centered on the petrous bone. The authors believe that patient outcomes are directly related to the degree of experience using this approach. Therefore, if this approach is to be used, they recommend collaboration with a skull base neurosurgeon.

A new fiber-mediated carbon dioxide laser facilitates pediatric spinal cord detethering. Technical note

OBJECT

The authors report their experience with a novel flexible fiber capable of transmitting CO(2) laser energy during spinal cord tumor resection and detethering.

METHODS

A fiber optic system capable of transmitting CO(2) laser energy was used in the detethering of the spinal cord in 3 cases. The first case involved a 9-year-old girl with a terminal lipoma. The second case was an 11-month-old boy with a thoracic intramedullary dermoid and dermal sinus tract. The third case involved a 13-year-old girl suffering from a tethered spinal cord subsequent to a previously repaired myelomeningocele.

RESULTS

In all 3 cases, the new fiber CO(2) laser technology allowed the surgeon to perform microsurgical dissection while sparing adjacent neurovascular structures without time-consuming setup. The system was easy to implement, more ergonomic than previous technologies, and safe. The CO(2) laser provided the ability to cut and coagulate while sparing adjacent tissue because of minimal energy dispersion and ease of use, without the articulating arms involved in the prior generation of lasers.

CONCLUSIONS

Using a flexible fiber to conduct CO(2) laser energy allows accurate microneurosurgical dissection and renders this instrument a high-precision and ergonomic surgical tool in the setting of spinal cord detethering.

Is postoperative CT scanning predictive of subdural electrode placement complications in pediatric epileptic patients?

AIMS

To understand the reliability of postoperative CT scans to predict the development of intracranial hemorrhagic complications associated with subdural electrode implants for monitoring intractable seizure, we reviewed the data of a consecutive series of children treated at our institution.

METHODS

Forty children (mean age: 11.4 years) with subdural electrode implants were reviewed. The immediate postoperative CT scans were evaluated for the presence of hemorrhagic complications and/or brain swelling resulting in a midline shift.

RESULTS

Twenty-six patients (65%) presented a postoperative midline shift (range = 2-10 mm; mean shift = 4.0 mm). Two children had a midline shift of >5 mm. Two patients with a shift of <5 mm at the first CT scan required a repeat craniotomy. These patients experienced worsening neurologic symptoms in a delayed fashion on postoperative days 1 and 4, respectively. This was correlated to an increase in midline shift of >5 mm.

CONCLUSIONS

Subdural electrode implants in children are safe. The presence of a midline shift of <5 mm is common postoperatively. The presence and extension of the midline shift at the first CT scan does not seem to be predictive of the development of symptomatic complications with a mass effect. Complications happened in a delayed fashion.

Failed age-dependent maturation of the occipital condyle in patients with congenital occipitoatlantal instability and Down syndrome: a preliminary analysis

OBJECT

Normative morphological data pertaining to the development of the occipital condyle have not been reported. The first goal of this study was to establish normative data characterizing the shape of the occipital condyle in healthy children. The second objective of the study was to compare these data with measurements collected in patients with congenital occipitoatlantal instability (COI) or Down syndrome (DS). The effectiveness of CT and plain radiography data was also compared.

METHODS

The authors retrospectively reviewed data obtained in 39 patients (14 with DS/COI and 25 age-matched controls). Patients underwent plain lateral radiography and CT scanning of the cervical spine. Normalized measurements of the occipital condyle were obtained for both groups using plain radiography and CT imaging techniques.

RESULTS

The curvature of the occipital condyle in healthy children increased by 60% from infancy to adolescence. Comparison of condylar morphology on plain lateral radiographs and CT scans in patients with DS/COI and in age-matched controls demonstrated a significant difference in mean normalized depth/length ratios. Comparison of curvature data obtained using plain lateral cervical radiography with measurements obtained using cervical CT scanning demonstrated a correlation coefficient of 0.63. However, intra- and interobserver reliability for plain radiographic analysis of the occipital condyle was poor (r(2) = 0.40 and 0.44, respectively).

CONCLUSIONS

Patient with DS/COI who have occipitoatlantal instability fail to develop the curved architecture in the occipital condyle that occurs in age-matched controls over time. Sagittal 2D CT reconstructions accurately determine the precise structure of the occipital condyle, although the indications for CT scanning are limited. Because of the poor intra- and interrater reliability on static plain radiographs, dynamic flexion/extension cervical spine radiographs remain the study of choice by which to directly evaluate occipitocervical motion.

Craniopagus twins

Craniopagus twins represent a rare phenomenon of congenital misfortune. Modern neurosurgical techniques have created opportunities for successful separation and the promise of a normal existence for these children, who in the past were often left as historical footnotes or put on display as oddities of nature. The authors document a brief history of conjoined twinning and discuss the modern science of craniopagus epidemiology, classification, and separation. In particular, the strategies used and the rationale for staged surgical separation are highlighted.

Surgical shunt infection: significant reduction when using intraventricular and systemic antibiotic agents

Object

Infection represents the most common serious complication of shunt surgery, and typically its incidence ranges between 5 and 15%, despite the use of systemic antibiotic agents. Because systemic antibiotic medications generally penetrate the cerebrospinal fluid (CSF) poorly, the authors investigated, in a controlled study, whether the addition of intraventricular antibiotic treatment decreases the incidence of perioperative infection in adult patients.

Methods

Data pertaining to all CSF shunt procedures conducted at the authors’ institution during an 11-year period were reviewed. Perioperative infection was defined as culture-positive CSF and the clinical presence of infection-related symptoms occurring within 90 days of surgery. All patients underwent intraoperative systemic antistaphylococcal antibiotic therapy. Before May 16, 1999, the senior author (R.H.S.) also administered 4 mg of gentamicin intraventricularly at surgery (Group I); thereafter, 10 mg of vancomycin was additionally administered (Group II). Other neurosurgeons at this institution did not use intraventricular antibiotic therapy, and their patients served as additional controls in identical time periods (Groups III and IV).

A total of 802 shunt procedures were performed in 534 patients. Control infection rates were 5.4% (eight of 147) in Group I; 6.2% (nine of 145) in Group III; and 6.7% (18 of 267) in Group IV. With the combination of systemic antibiotic and intraventricular gentamicin and vancomycin (Group II), the infection rate fell significantly to 0.4% (one of 243). No complications were noted in association with intraventricular antibiotic administration.

Conclusions

The combination of intraventricular gentamicin and vancomycin with systemic antibiotic therapy significantly decreased the incidence of perioperative shunt infection. It is presumed that intraventricular antibiotic therapy extends prophylactic antibiotic coverage into the CSF and prevents bacterial seeding.

N-myc can substitute for insulin-like growth factor signaling in a mouse model of sonic hedgehog-induced medulloblastoma

Medulloblastoma is a malignant brain tumor that arises in the cerebellum in children, presumably from granule neuron precursors (GNP). Advances in patient treatment have been hindered by a paucity of animal models that accurately reflect the molecular pathogenesis of human tumors. Aberrant activation of the Sonic hedgehog (Shh) and insulin-like growth factor (IGF) pathways is associated with human medulloblastomas. Both pathways are essential regulators of GNP proliferation during cerebellar development. In cultured GNPs, IGF signaling stabilizes the oncogenic transcription factor N-myc by inhibiting glycogen synthase kinase 3beta-dependent phosphorylation and consequent degradation of N-myc. However, determinants of Shh and IGF tumorigenicity in vivo remain unknown. Here we report a high frequency of medulloblastoma formation in mice following postnatal overexpression of Shh in cooperation with N-myc. Overexpression of N-myc, alone or in combination with IGF signaling mediators or with the Shh target Gli1, did not cause tumors. Thus, Shh has transforming functions in addition to induction of N-myc and Gli1. This tumor model will be useful for testing novel medulloblastoma therapies and providing insight into mechanisms of hedgehog-mediated transformation.

Failure of cerebrospinal fluid shunts: part II: overdrainage, loculation, and abdominal complications

Complications from cerebrospinal fluid shunts are common and can present with a variety of signs and symptoms. In this second part of a two-part review, shunt overdrainage, loculation of the ventricular system in patients with shunts, and abdominal complications related to ventriculoperitoneal shunts are discussed. Familiarity with these types of shunt failure is essential for neurologists and pediatricians because they are often the first to evaluate and triage these children.

Failure of cerebrospinal fluid shunts: part I: Obstruction and mechanical failure

Ventricular shunts are commonly employed to treat children with hydrocephalus. Complications from shunts are common and can present with a variety of signs and symptoms. This pair of reviews discusses the common findings in patients with shunt malfunction, including physical examination and imaging findings. Part I of the series discusses obstruction and mechanical failure of shunts; Part II discusses overdrainage, loculation, and abdominal complications of shunts. An understanding of the presentation and etiology of shunt dysfunction is critical for neurologists and pediatricians who often are the first to evaluate and triage these children.

Percutaneous dilational tracheostomy in neurosurgical patients

INTRODUCTION

Tracheostomy is often performed in patients requiring long-term mechanical ventilation after severe neurological injury. Percutaneous dilational tracheostomy (PDT) is an alternative to traditional surgical tracheostomy (TST) for creating a tracheostomy. We compared these techniques in neurosurgical patients and assessed the impact on cost and clinical course.

METHODS

We conducted a retrospective chart review of 81 neurosurgical patients treated with either PDT (n = 43) or TST (n = 38). Several clinical endpoints were examined, including days intubated prior to tracheostomy, length of hospital stay, procedural complications, and overall procedure costs.

RESULTS

No serious complications occurred with PDT, whereas two minor postoperative complications occurred in the TST group. The time from intubation to tracheostomy was 8 days for the PDT group versus 13 days for the TST group (p < 0.001), and the time from intubation to discharge from the hospital was 20 days for the PDT group compared to 27 days for the TST group (p < 0.005). In our institution, the average cost of PDT was $980.69 less than the cost for TST.

CONCLUSION

PDT appears to have a low incidence of complications in neurosurgical patients and may shorten the length of hospitalization and the overall cost compared with TST.

Prophylaxis for deep venous thrombosis in neurosurgery: a review of the literature

The incidence of deep venous thrombosis (DVT) and subsequent pulmonary embolism (PE) in patients undergoing neurosurgery has been reported to be as high as 25%, with a mortality rate from PE between 9 and 50%. Even with the use of pneumatic compression devices, the incidence of DVT has been reported to be 32% in these patients, making prophylactic heparin therapy desirable. Both unfractionated and low-molecular-weight heparin have been shown to reduce the incidence of DVT consistently by 40 to 50% in neurosurgical patients. The baseline rate for major intracranial hemorrhage (ICH) following craniotomy has been reported to be between 1 and 3.9%, but after initiation of heparin therapy this rate has been found to be as high as 10.9%. Therefore, neurosurgeons must balance the risk of PE against the increased risk of postoperative ICH from prophylactic heparin for DVT. The authors review the literature on the incidence of DVT and PE in neurosurgical patients, focusing on the incidence of ICH related to the use of unfractionated and low-molecular-weight heparin in this patient population

Craniopagus twins: embryology, classification, surgical anatomy, and separation

INTRODUCTION

With recent advances in brain imaging and neurosurgical techniques, there has been a renewed interest in the surgical separation of craniopagus twins. Successful separation in recent cases, along with widespread publicity, has attracted craniopagus twins from all over the world to be referred to pediatric neurosurgical centers for evaluation and consideration for surgical separation.

SEPARATION OF BLOOD SUPPLY

It has become apparent, however, that the most critical decisions in surgical planning are related to separation of the blood supply to the conjoined brains. In fact, in craniopagus twins that survive pregnancy or the first few days of life, there is usually little shared brain tissue. The shared blood supply is far and away the more critical issue. It is very difficult to successfully separate craniopagus twins in one surgical procedure. Staged separation, with gradual re-routing of the shared blood supply, has been a successful alternative.

CASE STUDIES AND DISCUSSION

We discuss here our experience with three sets of craniopagus twins and our approach to staged separation.

Semantic monitoring of words with emotional connotation during fMRI: contribution of anterior left frontal cortex

Previous studies showed that cortex in the anterior portions of the left frontal and temporal lobes participates in generating words with emotional connotations and processing pictures with emotional content. If these cortices process the semantic attribute of emotional connotation, they should be active whenever processing emotional connotation, without respect to modality of input or mode of output. Thus, we hypothesized that they would activate during monitoring of words with emotional connotations. Sixteen normal subjects performed semantic monitoring of words with emotional connotations, animal names, and implement names during fMRI. Cortex in the anterior left frontal lobe demonstrated significant activity for monitoring words with emotional connotations compared to monitoring tone sequences, animal names, or implement names. Together, the current and previous results implicate cortex in the anterior left frontal lobe in semantic processing of emotional connotation, consistent with connections of this cortex to paralimbic association areas. Current findings also indicate that neural substrates for processing emotional connotation are independent of substrates for processing the categories of living and nonliving things.

Left-hemisphere processing of emotional connotation during word generation

Areas of the brain's left hemisphere involved in retrieving words with emotional connotations were studied with fMRI. Participants silently generated words from different semantic categories which evoked either words with emotional connotations or emotionally neutral words. Participants repeated emotionally neutral words as a control task. Compared with generation of emotionally neutral words, generation of words with emotional connotations engaged cortices near the left frontal and temporal poles which are connected to the limbic system. Thus, emotional connotations of words are processed in or near cortices with access to emotional experience.

Activity in the paracingulate and cingulate sulci during word generation: an fMRI study of functional anatomy

The supracallosal medial frontal cortex can be divided into three functional domains: a ventral region with connections to the limbic system, an anterior dorsal region with connections to lateral prefrontal systems, and a posterior dorsal region with connections to lateral motor systems. Lesion and functional imaging studies implicate this medial frontal cortex in speech and language generation. The current functional magnetic resonance imaging (fMRI) study of word generation was designed to determine which of these three functional domains was substantially involved by mapping individual subjects' functional activity onto structural images of their left medial frontal cortex. Of 28 neurologically normal right-handed participants, 21 demonstrated a prominent paracingu- late sulcus (PCS), which lies in the anterior dorsal region with connections to lateral prefrontal systems. Activity increases for word generation centered in the PCS in 18 of these 21 cases. The posterior dorsal region also demonstrated significant activity in a majority of participants (16/28 cases). Activity rarely extended into the cingulate sulcus (CS) (3/21 cases) when there was a prominent PCS. If there was no prominent PCS, however, activity did extend into the CS (6/7 cases). In no case was activity present on the crest of the cingulate gyrus, which is heavily connected to the limbic system. Thus, current findings suggest that medial frontal activity during word generation reflects cognitive and motor rather than limbic system participation. The current study demonstrates that suitably designed fMRI studies can be used to determine the functional significance of anatomic variants in human cortex.

Prospective localization of epileptogenic foci: comparison of PET and SPECT with site of surgery and clinical outcome

PURPOSE

To correlate prospective imaging findings in patients with intractable partial epilepsy with site of surgery and clinical outcome.

MATERIALS AND METHODS

Thirty-five patients (25 male, 10 female) underwent positron emission tomography (PET; n=25), interictal single photon emission computed tomography (SPECT; n=33), or postictal SPECT (n=23) for localization of epileptogenic foci. The standard of reference was site of surgery.

RESULTS

Sensitivity was 60%, 61%, and 52%; positive predictive value was 83%, 71%, and 55%; and localization was incorrect in 12% (three of 25 cases), 24% (eight of 33 cases), and 43% (10 of 23 cases) in PET, interictal SPECT, and postictal SPECT, respectively. There was no statistically significant difference in localization capabilities in a comparison of interictal SPECT and PET (correct localization, P=.999; incorrect localization, P=.625). There was a trend toward higher incorrect localization with interictal SPECT.

CONCLUSION

Postictal SPECT has low sensitivity and a high incorrect localization rate and should not be performed in these patients. Interictal SPECT with 6-8-mm full-width at half-maximum is an alternative to PET. However, the trend toward higher false-localization rates must be taken into consideration.