Design and Physical Properties of 3-Dimensional Printed Models Used for Neurointervention

Neurosurgery DOI:10.1093/neuros/nyaa134

Three-dimensional (3D) printing has revolutionized training, education, and device testing. Understanding the design and physical properties of 3D-printed models is important.

OBJECTIVE: To systematically review the design, physical properties, accuracy, and experimental outcomes of 3D-printed vascular models used in neurointervention.

METHODS: We conducted a systematic review of the literature between January 1, 2000 and September 30, 2018. Public/Publisher MEDLINE (PubMed), Web of Science, Compendex, Cochrane, and Inspec databases were searched using Medical Subject Heading terms for design and physical attributes of 3D-printed models for neurointervention. Information on design and physical properties like compliance, lubricity, flow system, accuracy, and outcome measures were collected.

RESULTS: A total of 23 articles were included. Nine studies described 3D-printed models for stroke intervention. Tango Plus (Stratasys) was the most common material used to develop these models. Four studies described a population-representative geometry model. All other studies reported patient-specific vascular geometry. Eight studies reported complete reconstruction of the circle of Willis, anterior, and posterior circulation. Four studies reported a model with extracranial vasculature. One prototype study reported compliance and lubricity. Reported circulation systems included manual flushing, programmable pistons, peristaltic, and pulsatile pumps. Outcomes included thrombolysis in cerebral infarction, post-thrombectomy flow restoration, surgical performance, and qualitative feedback.

CONCLUSION: Variations exist in the material, design, and extent of reconstruction of vasculature of 3D-printed models. There is a need for objective characterization of 3D-printed vascular models. We propose the development of population representative 3D-printed models for skill improvement or device testing.

Failed Foramen Magnum Decompression in Chiari I Malformation Is Associated With Failure to Restore Normal Intracranial Compliance

Neurosurgery 86:E552–E557, 2020

The standard treatment for symptomatic Chiari malformation (CM) I is foramen magnum decompression (FMD) to facilitate cerebral spinal fluid flow through the foramen magnum, improve intracranial compliance, and alleviate symptoms (commonly headache). This procedure has a variable success rate, with a significant proportion of patients having persistent symptoms after surgery.

OBJECTIVE: To investigate intracranial pressure (ICP) hydrodynamics in symptomatic surgery-naïve patients with CM I and symptomatic patients who have had prior FMD.

METHODS: We undertook a retrospective, observational cohort study, extracting data from our departmental ICP database. Patients with untreated (“Virgin”) Chiari malformations (VCM), patients with previous “failed” FMD (ie, with persistent classical Chiari symptoms) (fFMD) and a normal control group, all with existing continuous ICP monitoring date were included. Median ICP (mICP) and median pulse amplitude (mPA) were compared between the groups.

RESULTS: A total of 33 CM patients (22 VCM and 11 fFMD) and 42 normal controls were included for analysis. mICP did not differ significantly between the normal control, VCM, and fFMD groups. mPA in the VCM and fFMD groups was significantly higher than the control group (P< .01 and P< .05, respectively).

CONCLUSION: In this cohort, patients with persistent symptoms after FMD have persistently impaired intracranial compliance, similar to patients who have not undergone surgery at all when compared with a control group. The reasons for this are not clear, and further research is required to establish the causation and optimum management for failed FMD.

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