Three-dimensional printing of a sinus pericranii model: technical note

Surgical Management of Sinus Pericranii With Crouzon Syndrome

BACKGROUND

Sinus pericranii (SP) is a rare vascular malformation which connects the intracranial dural sinuses to the extracranial venous drainage system. Although the majority of SP cases are caused by trauma, some of them are congenital. Furthermore, a few SP cases have been reported in association with craniosynostosis. The authors' objective is to discuss the surgical management of SP with Crouzon's syndrome in children.

METHODS

Three-Dimensional reconstruction with enhanced CT scan was used for evaluate the condition of SP with Crouzon's syndrome in all 4 cases. Two cases with small single-hole defect on skull were only treated by cranioplasty with distraction osteogenesis. In the management of the other 2 SP patients with large skull defect, titanium mesh was used for compression of dilated venous sinus to inhabit filling and promote shrinking.

RESULT

Four cases of SP with Crouzon's syndrome were treated in the authors' department. With cranioplasty with distraction osteogenesis only, 2 patients with single-hole skull defect experienced SP spontaneous involution at 4 to 6 months postoperatively. With titanium mesh compression, SP with large skull defect shrank significantly without clinical recurrence, but long-term follow-up was still in need.

CONCLUSION

For small single-hole skull defect in SP patient with Crouzon's syndrome, the only application of cranioplasty for decreasing intracranial pressure can promote SP spontaneous involution. 3D printed titanium mesh compression renders a safe and efficient approach for SP with large skull defect. Long-time follow up and further accumulation of cases may establish the efficacy of the authors' management.

Conventional and advanced MRI evaluation of brain vascular malformations

Vascular malformations (VMs) of the central nervous system (CNS) include a wide range of pathological conditions related to intra and extracranial vessel abnormalities. Although some VMs show typical neuroimaging features, other VMs share and overlap pathological and neuroimaging features that hinder an accurate differentiation between them. Hence, it is not uncommon to misclassify different types of VMs under the general heading of arteriovenous malformations. Thorough knowledge of the imaging findings of each type of VM is mandatory to avoid these inaccuracies. Conventional MRI sequences, including MR angiography, have allowed the evaluation of CNS VMs without using ionizing radiation. Newer MRI techniques, such as susceptibility-weighted imaging, black blood sequences, arterial spin labeling, and 4D flow imaging, have an added value of providing physiopathological data in real time regarding the hemodynamics of VMs. Beyond MR images, new insights using 3D printed models are being incorporated as part of the armamentarium for a noninvasive evaluation of VMs. In this paper, we briefly review the pathophysiology of CNS VMs, focusing on the MRI findings that may be helpful to differentiate them. We discuss the role of each conventional and advanced MRI sequence for VMs assessment and provide some insights about the value of structured reports of 3D printing to evaluate VMs.

Three-dimensional printing in medicine: a systematic review of pediatric applications

BACKGROUND

Three-dimensional printing (3DP) addresses distinct clinical challenges in pediatric care including: congenital variants, compact anatomy, high procedural risk, and growth over time. We hypothesized that patient-specific applications of 3DP in pediatrics could be categorized into concise, discrete categories of use.

METHODS

Terms related to "three-dimensional printing" and "pediatrics" were searched on PubMed, Scopus, Ovid MEDLINE, Cochrane CENTRAL, and Web of Science. Initial search yielded 2122 unique articles; 139 articles characterizing 508 patients met full inclusion criteria.

RESULTS

Four categories of patient-specific 3DP applications were identified: Teaching of families and medical staff (9.3%); Developing intervention strategies (33.9%); Procedural applications, including subtypes: contour models, guides, splints, and implants (43.0%); and Material manufacturing of shaping devices or prosthetics (14.0%). Procedural comparative studies found 3DP devices to be equivalent or better than conventional methods, with less operating time and fewer complications.

CONCLUSION

Patient-specific applications of Three-Dimensional Printing in Medicine can be elegantly classified into four major categories: Teaching, Developing, Procedures, and Materials, sharing the same TDPM acronym. Understanding this schema is important because it promotes further innovation and increased implementation of these devices to improve pediatric care.

IMPACT

This article classifies the pediatric applications of patient-specific three-dimensional printing. This is a first comprehensive review of patient-specific three-dimensional printing in both pediatric medical and surgical disciplines, incorporating previously described classification schema to create one unifying paradigm. Understanding these applications is important since three-dimensional printing addresses challenges that are uniquely pediatric including compact anatomy, unique congenital variants, greater procedural risk, and growth over time. We identified four classifications of patient-specific use: teaching, developing, procedural, and material uses. By classifying these applications, this review promotes understanding and incorporation of this expanding technology to improve the pediatric care.

A Simple Surgical Technique for Pediatric Sinus Pericranii: Intraoperative Manual Compression of a Major Shunting Point

INTRODUCTION

Sinus pericranii is a vascular anomaly with extra- and intracranial venous connections. Sinus pericranii is categorized into 2 groups according to its contribution to the normal venous circulation. The accessory type sinus pericranii, which does not contribute to the normal major venous circulation, can be managed. Despite several proposed operative maneuvers, a standardized technique is yet to be established to control intraoperative bleeding.

CASE PRESENTATION

A 2-week-old neonate underwent examination of a subcutaneous mass in the parieto-occipital region. The subcutaneous mass had a major venous connection to the superior sagittal sinus on ultrasonography. The subcutaneous mass was partially thrombolized on magnetic resonance imaging and was minimally enhanced on computed tomography venography. The subcutaneous mass seemed not to contribute to the normal venous circulation. Surgical removal of the subcutaneous mass was performed due to its increased size at the age of 1 year and 3 months. While subcutaneous mass was detached from the scalp, the major venous connection was manually compressed, and minor venous connections were easily detected. The intraoperative bleeding was controllable. The pathological diagnosis was sinus pericranii. The patient is now followed up in the outpatient clinic. No recurrence was seen 18 months after the surgery.

DISCUSSION/CONCLUSION

Intraoperative hemostasis is essential while sinus pericranii is detached from the cranium. Hemostatic agents such as bone wax or absorbable gelatin and heat coagulation seem to be useful. However, complicative hemorrhage concerning to the preceded technique has been also reported. As seen in our case, to detect minor shunting points between the sinus pericranii and the intracranial veins, the major venous connection was manually compressed. Intraoperative manual compression of a major venous connection of sinus pericranii can be an option to manage intraoperative bleeding.

Sound Measurement in Patient-Specific 3D Printed Bench Models of Venous Pulsatile Tinnitus

HYPOTHESIS

We hypothesize patient-specific flow models to be an adequate in vitro surrogate to allow for characterization of pulsatile tinnitus (PT) that affects three to five million Americans.

BACKGROUND

PT, rhythmic sounds without an extracorporeal source that patients appreciate, can be caused by aberrant blood flow in large cerebral veins near the cochlea. To investigate the sound production mechanism, we created 3D printed flow models based on patient-specific cerebral venous anatomies.

METHODS

Magnetic resonance angiography datasets from two patients with PT were used to generate patient-specific 3D printed flow models. A flow circuit connecting the patient-specific models to a pulsatile, continuous flow pump simulating cardiac cycle was created. Sound recordings were made along the surface of the models using an electronic stethoscope. Peak-to-rms amplitude, and area under the power spectral density (PSD) curve values were computed to evaluate the sound measurements. Wilcoxon rank sum test was used to statistically determine the differences in measurements between the patient-specific models.

RESULTS

In patient-1, the recordings (peak-to-rms) from the internal jugular vein stenosis of baseline model (4.29 ± 1.26 for 146 samples) were significantly louder (p < 0.001) than that of the altered model (3.29 ± 0.96 for 143 samples). In patient-2, the sound measured at the transverse sinus stenosis in the pre-lumbar puncture model (4.84 ± 1.11 for 148 samples) was significantly louder (p < 0.0001) than that of the post-lumbar puncture model (3.14 ± 0.87 for 135 samples).

CONCLUSIONS

The models are able to generate sounds very similar to those appreciated by patients and examiners in the cases of objective PT.

Dynamic morphological changes of thrombosed lateral sinus pericranii revealed by serial magnetic resonance images

BACKGROUND

Sinus pericranii (SP) is a rare venous anomaly involving an abnormal connection of the intracranial dural sinuses with the extracranial veins. Magnetic resonance (MR) imaging (MRI) with MR venography can detect the typically congested intra- and extracranial venous components of SP.

CLINICAL PRESENTATION

We report a rare case of lateral SP associated with the superior sagittal sinus, which might had already developed almost total thrombosis of the SP at the first MRI. As this patient had not presented with classical manifestations of SP on clinical or neuroradiological findings, the initial diagnosis of SP was difficult. Repeated MRI revealed dynamic morphological changes associated with reperfusion of the thrombosed SP via the cortical vein.

CONCLUSION

MR venography combined with gadolinium enhancement was useful for diagnosis of the SP with an extremely slow flow status.