The Shunt Valve Recession Technique as a Neuroplastic Surgery Adjunct in Complex and High-Risk Shunt Revisions: Technical Note and Case Series.

BACKGROUND AND OBJECTIVES: Ventricular shunting is one of the most common procedures in neurosurgery. However, complications and revisions are frequent. Patients requiring multiple revisions often suffer secondary issues with scalp healing over hardware. Many common ventricular shunt valves have an obligate thickness that creates a visible protrusion and can potentially cause local tissue ischemia and breakdown in the setting of repeated surgery. The authors present a simple technique for recessing the shunt valve into the underlying bone to alleviate protrusion in high-risk cases. Three example cases utilizing this technique are presented. METHODS: The skull directly underlying the planned valve site is uniformly recessed with a cutting burr several millimeters as desired while maintaining the inner cortical bone layer. The valve is fixed with standard cranial plating hardware. EXPECTED OUTCOMES: Three patients are reported who underwent shunt valve recession as an adjunct to their shunt revision with neuroplastic surgery assistance. All patients had undergone multiple prior surgeries that had resulted in thin and high-risk fragile scalp. In 1 patient, the prior valve was eroding through the scalp before the described revision. All patients had satisfactory cosmetic outcomes, and there were no revisions in the 2-month follow-up period. DISCUSSION: Complex and high-risk ventricular shunt patients should be considered for shunt valve recession into the bone to reduce wound-related complications and enhance healing. This is a technically simple, safe, and effective technique to include as a neuroplastic adjunct.

Adult Age Differences in Self-Reported Pain and Anterior CSF Space in Chiari Malformation.

Chiari malformation type I (CMI) is a neural disorder with sensory, cognitive, and motor defects, as well as headaches. Radiologically, the cerebellar tonsils extend below the foramen magnum. To date, the relationships among adult age, brain morphometry, surgical status, and symptom severity in CMI are unknown. The objective of this study was to better understand the relationships among these variables using causal modeling techniques. Adult CMI patients (80% female) who either had (n = 150) or had not (n = 151) undergone posterior fossa decompression surgery were assessed using morphometric measures derived from magnetic resonance images (MRI). MRI-based morphometry showed that the area of the CSF pocket anterior to the cervico-medullary junction (anterior CSF space) correlated with age at the time of MRI (r = - .21). Also, self-reported pain increased with age (r = .11) and decreased with anterior CSF space (r = - .18). Age differences in self-reported pain were mediated by anterior CSF space in the cervical spine area-and this effect was particularly salient for non-decompressed CMI patients. As CMI patients age, the anterior CSF space decreases, and this is associated with increased pain-especially for non-decompressed CMI patients. It is recommended that further consideration of age-related decreases in anterior CSF space in CMI patients be given in future research.

Impact of Surgical Status, Loneliness, and Disability on Interleukin 6, C-Reactive Protein, Cortisol, and Estrogen in Females with Symptomatic Type I Chiari Malformation.

Chiari malformation type I (CMI) provides an opportunity for examining possible moderators of allostatic load. CMI patients who had (n = 43) and had not (n = 19) undergone decompression surgery completed questionnaires regarding pain, disability, and loneliness, and provided serum samples for IL-6, CRP, estrogen, and free estradiol assays, and saliva samples to assess diurnal cortisol curves. ANOVAs examining surgical status (decompressed versus non-decompressed), loneliness (high vs. low), and disability (high vs. low) as independent variables and biomarker variables as dependent factors found that loneliness was associated with higher levels of cortisol, F(1, 37) = 4.91, p = .04, η2P = .11, and lower levels of estrogen, F(1, 36) = 7.29, p = .01, η2P = .17, but only in decompressed patients. Results highlight the possible impact of loneliness on biological stress responses and the need to intervene to reduce loneliness in patients with symptomatic CMI.

Assessing the predictive value of common gait measure for predicting falls in patients presenting with suspected normal pressure hydrocephalus.

OBJECTIVE: To assess the predictive value of common measures validated to predict falls in other geriatric populations in patients presenting with suspected Normal Pressure Hydrocephalus (NPH). METHODS: One hundred ninety-five patients over the age of 60 who received the Fall Risk Questionnaire were retrospectively recruited from the CSF Disorders clinic within the departments of Neurosurgery and Neurology. Multiple logistic regression was used to create a model to predict falls for patients with suspected NPH using common measures: Timed Up & Go, Dual Timed Up & Go, 10 Meter Walk, MiniBESTest, 6-Minute Walk, Lower Extremity Function (Mobility), Fall Risk Questionnaire, and Functional Activities Questionnaire. RESULTS: The Fall Risk Questionnaire and age were shown to be the best predictors of falls. The model was 95.92% (Positive predictive value: 83.93%) sensitive and 47.92% specific (Negative predictive value: 77.78%). CONCLUSION: Patients presenting with suspected NPH are at an increased fall risk, 75% of the total patients and 89% of patients who responded to a temporary drain of CSF had at least one fall in the past 6 months. The Fall Risk Questionnaire and age were shown to be predictive of falls for patients with suspected NPH. The preliminary evidence indicates measures that have been validated to assess fall risk in other populations may not be valid for patients presenting with suspected NPH.

Extended lumbar drainage in idiopathic normal pressure hydrocephalus: a systematic review and meta-analysis of diagnostic test accuracy.

BACKGROUND: When appropriately selected, a high proportion of patients with suspected idiopathic normal pressure hydrocephalus (iNPH) will respond to cerebrospinal fluid diversion with a shunt. Extended lumbar drainage (ELD) is regarded as the most accurate test for this condition, however, varying estimates of its accuracy are found in the current literature. Here, we review the literature in order to provide summary estimates of sensitivity, specificity, positive- and negative predictive value for this test through meta-analysis of suitably rigorous studies. METHODS: Studies involving a population of NPH patients with predominantly idiopathic aetiology (>80%) in which the intention of the study was to shunt patients regardless of the outcome of ELD were included in the review. Various literature databases were searched to identify diagnostic test accuracy studies addressing ELD in the diagnosis of iNPH. Those studies passing screening and eligibility were assessed using the QUADAS-2 tool and data extracted for bivariate random effects meta-analysis. RESULTS: Four small studies were identified. They showed disparate results concerning diagnostic test accuracy. The summary estimates for sensitivity and specificity were 94% (CI 41-100%) and 85% (CI 33-100%), respectively. The summary estimates of positive and negative predictive value were both 90% (CIs 65-100% and 48-100%, respectively). CONCLUSION: Large, rigorous studies addressing the diagnostic accuracy of ELD are lacking, and little robust evidence exists to support the use of ELD in diagnostic algorithms for iNPH. Therefore, a large cohort study, or ideally an RCT, is needed to determine best practice in selecting patients for shunt surgery.

The Impact of Hydrocephalus Shunt Devices on Quality of Life.

BACKGROUND: Despite advances in hydrocephalus shunt technology and improvement in hydrocephalus management, many patients have chronic disability and require multiple surgeries throughout their lifetime. There is limited data from patients' perspective regarding the impact of shunt devices on quality-of-life. METHODS: A cross-sectional survey was developed to evaluate the impact of shunt devices on patient quality-of-life. The survey was distributed via social media platforms of the Hydrocephalus Association, and patients self-selected to anonymously complete the online questionnaire. A literature review was performed to contextualize the findings from the survey. RESULTS: A total of 562 survey responses were obtained from a network encompassing 35,000 members. The mean age was 30 years old (0.5-87), and 65% identified as female. Eighty one percent underwent at least 1 shunt revision surgery, with a reported average of 10 shunt revision surgeries per patient (1-200 surgeries). Occlusion, shunt migration and infection were the leading causes for revision at 60%, 47%, and 35%, respectively. In addition, 72% of patients reported pain and discomfort from the device, and 68% expressed avoidance of certain activities due to "fear of bumping shunt." Despite numerous articles discussing shunt technology, a review of the literature indicated a paucity of studies specifically evaluating the burden of shunt devices from a patient/caregiver perspective. CONCLUSIONS: The findings from this study suggest long-term physical and psychosocial burden associated with shunt devices. Importantly, this study highlights the need for concerted efforts to develop validated tools to study patient reported outcomes as it relates to neurocranial implanted devices.

Standardized regression-based clinical change score cutoffs for normal pressure hydrocephalus.

BACKGROUND: Presently, for patients presenting with suspected Normal Pressure Hydrocephalus (NPH) who undergo temporary drainage of cerebrospinal fluid (CSF) there is no defined model to differentiate chance improvement form clinical significance change at the individual patient level. To address this lack of information we computed standard regression based clinical change models for the 10 Meter Walk Test, Timed Up & Go, Dual Timed Up & Go, 6-Minute Walk Test, Mini-Balance Evaluation Systems Test, Montreal Cognitive Assessment, and Symbol Digit Modalities using data from patients with suspected NPH that underwent temporary drainage of CSF. These clinically significant change modes can classify clinically significant improvement following temporary drainage of CSF at the individual patient level. This allows for physicians to differentiate a clinically significant improvement in symptoms from chance improvement. METHODS: Data was collected from 323 patients, over the age of 60, with suspected NPH that underwent temporary drainage of CSF with corresponding gait and cognitive testing. McSweeney Standardized Regression Based Clinical Change Models were computed for standard gait and cognitive measures: Timed Up & Go, Dual Timed Up & Go, 10 Meter Walk Test, MiniBESTest, 6-Minute Walk Test, Montreal Cognitive Assessment, and Symbol Digit Modalities Test. To assess the discriminate validity of the measures we used correlations, Chi2, and regression analyses. RESULTS: The clinical change models explained 69-91.8% of the variability in post-drain performance (p <  0.001). As patient scores became more impaired, the percent change required for improvement to be clinically significant increased for all measures. We found that the measures were not discriminate, the Timed Up & Go was highly related to the 10 Meter Walk Test (r = 0.85, R2 = 0.769-0.738, p <  0.001), MiniBESTest (r = - 0.67, R2 = 0.589-0.734, p <  0.001), and 6 Minute Walk Test (r = - 0.77, R2 = 0.71-0.734, p <  0.001). CONCLUSION: Standardized Regression Based Clinically Significant Change Models allow for physicians to use an evidence-based approach to differentiate clinically significant change from chance improvement at the individual patient level. The Timed Up & Go was shown to be predictive of detailed measures of gait velocity, balance, and endurance.

Evidence of Neural Microstructure Abnormalities in Type I Chiari Malformation: Associations Among Fiber Tract Integrity, Pain, and Cognitive Dysfunction.

BACKGROUND: Previous case-control investigations of type I Chiari malformation (CMI) have reported cognitive deficits and microstructural white matter abnormalities, as measured by diffusion tensor imaging (DTI). CMI is also typically associated with pain, including occipital headache, but the relationship between pain symptoms and microstructure is not known. METHODS: Eighteen CMI patients and 18 adult age- and education-matched control participants underwent DTI, were tested using digit symbol coding and digit span tasks, and completed a self-report measure of chronic pain. Tissue microstructure indices were used to examine microstructural abnormalities in CMI as compared with healthy controls. Group differences in DTI parameters were then reassessed after controlling for self-reported pain. Finally, DTI parameters were correlated with performance on the digit symbol coding and digit span tasks within each group. RESULTS: CMI patients exhibited greater fractional anisotropy (FA), lower radial diffusivity, and lower mean diffusivity in multiple brain regions compared with controls in diffuse white matter regions. Group differences no longer existed after controlling for self-reported pain. A significant correlation between FA and the Repeatable Battery for the Assessment of Neuropsychological Status coding performance was observed for controls but not for the CMI group. CONCLUSIONS: Diffuse microstructural abnormalities appear to be a feature of CMI, manifesting predominantly as greater FA and less diffusivity on DTI sequences. These white matter changes are associated with the subjective pain experience of CMI patients and may reflect reactivity to neuroinflammatory responses. However, this hypothesis will require further deliberate testing in future studies.

Investigation of a Valve-Agnostic Cranial Implant for Adult Hydrocephalus Patients Requiring Ventriculoperitoneal Shunting.

INTRODUCTION: Currently, the most effective treatment strategy for adults with hydrocephalus involves cerebrospinal fluid diversion by means of a shunt system, most commonly ventriculoperitoneal shunts (VPS). Ventriculoperitoneal shunting is associated with high complication and/or revision rates, in part due to the high-profile programmable valve designs. Thus, the valve-agnostic cranial implant (VACI) was designed and investigated as a safe and effective method of reducing the valve's high profile and is currently undergoing clinical trials. As such, the objective of this study was to collate preliminary, multi-institutional data of early outcomes using a VACI approach for patients requiring VPS by way of an Institutional Review Board approved registry. METHODS: A total of 25 adult patients across 4 institutions and 6 surgeons underwent VACI placement for VPS based on preoperative evaluation and perceived benefit. Patient demographics, operative details, and preliminary outcomes are presented here. RESULTS: Valve-agnostic cranial implant placement via a limited size craniectomy at time of shunt revision was performed with no adverse events. Over an average follow-up period of 1 year (394 ±â€Š178 days), 92% of patients experienced no major shunt-related or scalp-related complications. There were 2 cases with a major complication requiring reoperation: 1 shunt tubing extrusion and 1 case of meningitis. The most frequent postsurgical intervention seen in this study was related to adjustment of drainage: a non-invasively performed valve reprogramming after initial shunt placement when proper flow rate is being established. Of the 8 cases of drainage adjustment, all but 1 (88%) were receiving a VPS for the first time, with the exception undergoing a fourth shunt revision. All instances of improper flow were treated non-surgically and remediated effectively via shunt reprogramming in clinic. Removal of the VACI was not indicated in any treatment course. In this way, all complications as they relate to the shunt valve were minor and required nonsurgical intervention, and no complications reported were directly or indirectly caused by using the VACI. CONCLUSION: Preliminary findings from this multicenter trial suggest promising outcomes with a low complication rate for patients with hydrocephalus undergoing VACI placement during VPS. Ongoing research will continue to provide a more robust clinical picture of VACI in hydrocephalus management as more data becomes available.

An Electrophysiological Study of Cognitive and Emotion Processing in Type I Chiari Malformation.

Type I Chiari malformation (CMI) is a neurological condition in which the cerebellar tonsils descend into the cervical spinal subarachnoid space resulting in cervico-medullary compression. Early case-control investigations have indicated cognitive deficits in the areas of attention, memory, processing speed, and visuospatial function. The present study further examined cognitive and emotional processing deficits associated with CMI using a dual-task paradigm. Nineteen CMI patients were recruited during pre-surgical consultation and 19 matched control participants identified emotional expressions in separate single and asynchronous dual-task designs. To extend earlier behavioral studies of cognitive effects in CMI, we recorded event-related potentials (ERPs) in the dual-task design. Though response times were slower for CMI patients across the two tasks, behavioral and ERP analyses indicated that patients did not differ from matched controls in the ability to allocate attentional resources between the two tasks. P1 ERP component analyses provided no indication of an emotional arousal deficit in our CMI sample while P3 ERP component analyses suggested a CMI-related deficit in emotional regulation. P3 analysis also yielded evidence for a frontalization of neurophysiological activity in CMI patients. Pain and related depression and anxiety factors accounted for CMI deficits in single-task, but not dual-task, response times. Results are consistent with a dysfunctional fronto-parietal attentional network resulting from either the indirect effects of chronic pain or the direct effects of CMI pathophysiology stemming from cervico-medullary compression.

A morphometric assessment of type I Chiari malformation above the McRae line: A retrospective case-control study in 302 adult female subjects.

PURPOSE: Type I Chiari malformation (CMI) is a radiologically-defined structural dysmorphism of the hindbrain and posterior cranial fossa (PCF). Traditional radiographic identification of CMI relies on the measurement of the cerebellar tonsils in relation to the foramen magnum with or without associated abnormalities of the neuraxis. The primary goal of this retrospective study was to comprehensively assess morphometric parameters above the McRea line in a group of female CMI patients and normal controls. MATERIAL AND METHODS: Twenty-nine morphological measurements were taken on 302 mid-sagittal MR images of adult female CMI patients (n=162) and healthy controls (n=140). All MR images were voluntarily provided by CMI subjects through an online database and control participant images were obtained through the Human Connectome Project and a local hospital system. RESULTS: Analyses were performed on the full dataset of adult female MR images and a restricted dataset of 229 participants that were equated for age, race, and body mass index. Eighteen group differences were identified in the PCF area that we grouped into three clusters; PCF structures heights, clivus angulation, and odontoid process irregularity. Fourteen group differences persisted after equating our CMI and control groups on demographic characteristics. CONCLUSION: PCF structures reliably differ in adult female CMI patients relative to healthy controls. These differences reflect structural abnormalities in the osseous and soft tissue structures of the clivus, odontoid process, and cerebellum. Clinical and pathophysiological implications are discussed.

Longitudinal Metabolite Profiling of Cerebrospinal Fluid in Normal Pressure Hydrocephalus Links Brain Metabolism with Exercise-Induced VEGF Production and Clinical Outcome.

Idiopathic normal pressure hydrocephalus is a neurological disease caused by abnormal cerebrospinal fluid flow and presents with symptoms such as dementia. Current therapy involves the removal of excess cerebrospinal fluid by shunting. Not all patients respond to this therapy and biomarkers are needed that could facilitate the characterization of patients likely to benefit from this treatment. Here, we measure brain metabolism in normal pressure hydrocephalus patients by performing a novel longitudinal metabolomic profiling study of cerebrospinal fluid. We find that the levels of brain metabolites correlate with clinical parameters, the amount of vascular endothelial growth factor in the cerebrospinal fluid, and environmental stimuli such as exercise. Metabolomic analysis of normal pressure hydrocephalus patients provides insight into changes in brain metabolism that accompany cerebrospinal fluid disorders and may facilitate the development of new biomarkers for this condition.

Cerebrospinal fluid flow impedance is elevated in Type I Chiari malformation.

Diagnosis of Type I Chiari malformation (CMI) is difficult because the most commonly used diagnostic criterion, cerebellar tonsillar herniation (CTH) greater than 3-5 mm past the foramen magnum, has been found to have little correlation with patient symptom severity. Thus, there is a need to identify new objective measurement(s) to help quantify CMI severity. This study investigated longitudinal impedance (LI) as a parameter to assess CMI in terms of impedance to cerebrospinal fluid motion near the craniovertebral junction. LI was assessed in CMI patients (N = 15) and age-matched healthy controls (N = 8) using computational fluid dynamics based on subject-specific magnetic resonance imaging (MRI) measurements of the cervical spinal subarachnoid space. In addition, CTH was measured for each subject. Mean LI in the CMI group (551 ± 66 dyn/cm5) was significantly higher than in controls (220 ± 17 dyn/cm5, p < 0.001). Mean CTH in the CMI group was 9.0 ± 1.1 mm compared to -0.4 ± 0.5 mm in controls. Regression analysis of LI versus CTH found a weak relationship (R2 = 0.46, p < 0.001), demonstrating that CTH was not a good indicator of the impedance to CSF motion caused by cerebellar herniation. These results showed that CSF flow impedance was elevated in CMI patients and that LI provides different information than a standard CTH measurement. Further research is necessary to determine if LI can be useful in CMI patient diagnosis.

Cortical Laminar Necrosis After Severe Hydrocephalus: Case Report and Review of the Literature.

Objectives: We present a case of cortical laminar necrosis after severe hydrocephalus to highlight considerations for multimodal cerebral autoregulation monitoring to determine mean arterial pressure (MAP) thresholds during neurological emergencies, as well as postoperative head imaging for patients with ventriculoperitoneal shunts (VPS). Methods: A 40-year-old woman with a history of Chiari II malformation and non-communicating hydrocephalus with VPS presented in septic shock from a sacral wound. One week after colostomy for fecal diversion, the patient became comatose and had progressive slowing to full suppression on electroencephalogram (EEG). Results: CT imaging revealed hydrocephalus, most likely due to VPS distal obstruction from intraperitoneal surgery. Despite neurosurgical and neurocritical care management, MRI confirmed diffuse cortical hypoxic ischemic injury. Discussion: The Neurocritical Care Society's Emergency Neurological Life Support (ENLS) protocol for neurological emergencies focuses on managing increased intracranial pressure (ICP) but does not set MAP goals. As ICP may be very high during brain herniation, our case demonstrates that higher MAP may be required to maintain adequate circulation. To determine the optimal MAP target, bedside multimodality monitoring, including ICP monitors, transcranial doppler, and near infrared spectroscopy, can help establish individualized cerebral autoregulation guided thresholds. Outside of a neurological intensive care unit, EEG can monitor cerebral blood flow and indicate windows for intervention before exam or imaging changes. Additionally, our case demonstrates how a post-operative surveillance CT head should be considered for patients with VPS.

Molecular Signatures of Normal Pressure Hydrocephalus: A Largescale Proteomic Analysis of Cerebrospinal Fluid.

Given the persistent challenge of differentiating idiopathic Normal Pressure Hydrocephalus (iNPH) from similar clinical entities, we conducted an in-depth proteomic study of cerebrospinal fluid (CSF) in 28 shunt-responsive iNPH patients, 38 Mild Cognitive Impairment (MCI) due to Alzheimer's disease, and 49 healthy controls. Utilizing the Olink Explore 3072 panel, we identified distinct proteomic profiles in iNPH that highlight significant downregulation of synaptic markers and cell-cell adhesion proteins. Alongside vimentin and inflammatory markers upregulation, these results suggest ependymal layer and transependymal flow dysfunction. Moreover, downregulation of multiple proteins associated with congenital hydrocephalus (e.g., L1CAM, PCDH9, ISLR2, ADAMTSL2, and B4GAT1) points to a possible shared molecular foundation between congenital hydrocephalus and iNPH. Through orthogonal partial least squares discriminant analysis (OPLS-DA), a panel comprising 13 proteins has been identified as potential diagnostic biomarkers of iNPH, pending external validation. These findings offer novel insights into the pathophysiology of iNPH, with implications for improved diagnosis.

Complications of intrathecal baclofen pumps in children: experience from a tertiary care center.

BACKGROUND/AIMS: Intrathecal baclofen (ITB) therapy is useful in treating spasticity and dystonia but it has many complications, more so in children. The main aim of the study was to look at the complications of ITB pumps in children with the goal of future prevention. METHODS: Charts of all patients ≤21 years with an ITB pump, implanted by a single pediatric neurosurgeon, at a single center, between 1996 and 2011 were reviewed retrospectively. Data regarding an ITB test trial were also recorded. RESULTS: During 1996-2011, 119 children (mean age 13.2 years) underwent ITB pump placement; 84% had spastic quadriplegic cerebral palsy. The gross motor function classification system level was ≥4 for most. The pump was removed in 5 (4.2%) patients due to inefficacy. The mean follow-up was 38 months. Mechanical complications requiring pump and/or catheter revision occurred in 19.3% and infections in an additional 21.8%. Seven patients (6%) had meningitis. No complication was noted after 72 months of initial pump insertion, even after pump reinsertion. CONCLUSION: There is a need for better infection control as well as better pump, catheter and surgical technology to lower the complications of ITB pumps in children.

Modifying the ICP pulse wave: effects on parenchymal blood flow pulsatility.

Pulsation of the cerebral blood flow (CBF) produces intercranial pressure (ICP) waves. The aim of this study is to determine whether externally modifying ICP pulsatility alters parenchymal blood flow pulsatility. A cardiac-gated inflatable device was inserted in the lateral epidural space of 12 anesthetized canines (canis familiaris) and used to cause reduction, inversion, and augmentation of the ICP pulse. CBF in each hemisphere was measured using laser Doppler velocimetry. A significant increase in both mean CBF and its amplitude was observed for reduction as well as inversion of the ICP pulse, with larger changes observed for the inversion protocol. Significant increases in the mean CBF were also observed ipsilaterally for the augmentation protocol together with indications of reduced CBF amplitude contralaterally. External alteration of the ICP pulse thus caused significant changes in parenchymal blood flow pulsatility. The inverse relationship between the ICP and CBF amplitude suggests that the changes did not occur via modification of the intracranial Windkessel mechanism. Thus, the effects likely occurred in the low-pressure vessels, i.e., capillaries and/or venules, rather than the high-pressure arteries. Future MRI studies are however required to map and quantify the effects on global cerebral blood flow.NEW & NOTEWORTHY This study demonstrated that external modification of ICP pulsatility, using a cardiac-gated inflatable device implanted epidurally in canines, alters brain tissue blood flow pulsatility. Specifically, decreasing systolic ICP increased blood flow pulsatility in brain tissue. The results suggest that the altered CBF pulsatility is unlikely to depend on modification of the Windkessel effect on the feeding arterial system but was rather an effect directly on tissue and the lower pressure distal vessels.

Establishing proof of concept for sonolucent cranioplasty and point of care ultrasound imaging after posterior fossa decompression for Chiari malformation.

BACKGROUND: Evaluation after posterior fossa decompression for Chiari malformation can require repeated imaging, particularly with persistent symptoms. Typically, CT or MRI is used. However, CT carries radiation risk and MRI is costly. Ultrasound is an inexpensive, radiation-free, point-of-care modality that has, thus far, been limited by intact skull and traditional cranioplasty materials. Ultrasound also allows for imaging in different head positions and body postures, which may lend insight into cause for persistent symptoms despite adequate decompression on traditional neutral static CT or MRI. We evaluate safety and feasibility of ultrasound as a post-operative imaging modality in patients reconstructed with sonolucent cranioplasty during posterior fossa decompression for Chiari malformation. METHODS: Outcomes were analyzed for 26 consecutive patients treated with a Chiari-specific sonolucent cranioplasty. This included infection, need for revision, CSF leak, and pseudomeningocele. Ultrasound was performed point-of-care in the outpatient clinic by the neurosurgery team to assess feasibility. RESULTS: In eight months mean follow up, there were no surgical site infections or revisions with this novel sonolucent cranioplasty. Posterior fossa anatomy was discernable via transcutaneous ultrasound obtained point-of-care in the clinic setting at follow up visits. CONCLUSION: We demonstrate proof of concept for ultrasound as a post-operative imaging modality after posterior fossa decompression for Chiari malformation. With further investigation, ultrasound may prove to serve as an alternative to CT and MRI in this patient population, or as an adjunct to provide positional and dynamic information. Use of sonolucent cranioplasty is safe. This technique deserves further study.

First Experience With Postoperative Transcranial Ultrasound Through Sonolucent Burr Hole Covers in Adult Hydrocephalus Patients.

BACKGROUND: Managing patients with hydrocephalus and cerebrospinal fluid (CSF) disorders requires repeated head imaging. In adults, it is typically computed tomography (CT) or less commonly magnetic resonance imaging (MRI). However, CT poses cumulative radiation risks and MRI is costly. Ultrasound is a radiation-free, relatively inexpensive, and optionally point-of-care alternative, but is prohibited by very limited windows through an intact skull. OBJECTIVE: To describe our initial experience with transcutaneous transcranial ultrasound through sonolucent burr hole covers in postoperative hydrocephalus and CSF disorder patients. METHODS: Using cohort study design, infection and revision rates were compared between patients who underwent sonolucent burr hole cover placement during new ventriculoperitoneal shunt placement and endoscopic third ventriculostomy over the 1-year study time period and controls from the period 1 year before. Postoperatively, trans-burr hole ultrasound was performed in the clinic, at bedside inpatient, and in the radiology suite to assess ventricular anatomy. RESULTS: Thirty-seven patients with sonolucent burr hole cover were compared with 57 historical control patients. There was no statistically significant difference in infection rates between the sonolucent burr hole cover group (1/37, 2.7%) and the control group (0/57, P = .394). Revision rates were 13.5% vs 15.8% (P = 1.000), but no revisions were related to the burr hole or cranial hardware. CONCLUSION: Trans-burr hole ultrasound is feasible for gross evaluation of ventricular caliber postoperatively in patients with sonolucent burr hole covers. There was no increase in infection rate or revision rate. This imaging technique may serve as an alternative to CT and MRI in the management of select patients with hydrocephalus and CSF disorders.