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Immediate Application Cranioplasty During Decompressive Craniectomy for Head Injuries


OBJECTIVE: To develop a Cranioplasty construct for immediate application during Decompresive Craniectomy for relief of increased intracranial pressure refractory to medical management. The construct spares the costs of a delayed Cranioplasty. DESCRIPTION: Decompressive Craniectomy(ies) (DC) or the neurosurgical emergency procedure removing part of the skull to relieve brain pressure from traumatic injuries have been widely employed during the OIF/OEF period to ensure wartime head injury patient survival for long transport to tertiary medical treatment facilities(1, 2). The skull defect that results while awaiting a second-staged procedure to cover this defect (Cranioplasty) has given rise to an intervening disorder, the Syndrome of the Trephined (ST), which causes behavioral and motor deficits in patients and compromise their ability to carry out rehabilitative treatment, thus prolonging their hospital stay(3-5). The current surgical practice of waiting for an average of 6 months before subjecting the craniectomized patient to Cranioplasty was influenced by by Rish and co-workers6who in a 1979 publication of a large series of open head injuries recommended a minimum waiting period of 1 year to avoid infections associated with Cranioplasties. During the 2002-08 period, the Walter Reed Army Medical Center (WRAMC)-Neurosurgery compared the craniectomy-cranioplasty interval with the incidence of CNS infection to validate the conclusions made in the late"70s by Rish, et al that craniectomies done earlier than 6 months were prone to infection. Of the 188 craniectomies done by WRAMC-Neurosurgery during the 2002-08 period, 144 cases qualified as having reliable clinical data to determine their respective craniectomy cranioplasty interval periods which ranged from 11 days to 36 months (extent shortened to 19 months in the depicted graph). CNS infection cases (n=25) all had documented positive cultures taken from the craniectomy site. The data7 showed a period of lesser infection incidence at the early end of the interval period range (<3 month interval). Of the 23 patients who underwent cranioplasty<3 months from craniectomy in our series, only one CNS infected case was detected. The isolated infection case showing Streptococcus viridians growth in the CSF, occurring within the<3 month interval period (2 months post-Craniectomy) was that of an allied NATO soldier referred from a non-US military health facility. Although smaller than the 1030 patient review cited by Rish, et al for penetrating head injuries, results on the Craniectomy-Cranioplasty interval analysis for our series include both penetrating and closed head injuries and favor a paradigm shift from the current practice of staging late (>6 months - 1 year) cranioplasties for craniectomized head injuries. Previously cited publications (8-14) support important predictors for CNS infections other than timing for the Cranioplasty procedure and more importantly, signify that it is not the waiting period for the Cranioplasty procedure per se, but the interruption of wound healing, as seen in staged or operative revisions, that increases the infection risk. Since the least wound healing interruption is accomplished during the initial craniectomy, the development of a cranioplasty construct suited for simultaneous application during Decompressive Craniectomy spares the patient from a second surgery. It is to be noted that the current commercially available cranioplasty constructs are all designed for a second staged surgical procedure since they do not address the brain swelling found with Decompressive Craniectomies of acute head injuries. A semi-rigid cranioplasty construct which conforms to the expansion of the brain and its outer layer (dura) during brain edema and adapt to its normal contour upon its resolution will provide the technical gap to make this one-staged procedure viable. PHASE I: In Phase I, the performer will demonstrate the feasibility of the Cranioplasty construct design by computer simulation and 3D Model Testing. First, by noting the different time points of brain swelling on neuroimaging from its intitiation to its cessation from MRI images of head injury patients who have undergone Decompressive Craniectomy, a temporal profile of the brain swelling event will be created. Time gaps found between the available MRI images will be filled through a computer process called rendering. Secondly, the cranioplasty design, which would be based on actual post-craniectomy skull defects, will be simulated as well, as it interacts with the event of brain swelling. This can be done by utilizing available software (MIMICS) used for configuring neuroimaging (MRI, CT) into viewable and movable 3D images. These digital images will also be transformed into 3D plastic/rubber models of a phantom skull and brain which can be mechanically observed as they interact with event of brain swelling through a process known as stereolithography. A brain phantom setup will be created using a gelatin-filled elastic capsule containing two inner tubes with inflatable tips each constructed to the known 12% capacities of blood vessels and of CSF respective to the total brain volume fitting the intracranial cavity of the skull models(15). Based on 100 simulation trials to be carried out interplaying the cerebral edema event with the cranioplasty design both on the virtual and the 3D model levels, the outcome will iterate to an alpha prototype system, Cranioplasty Prototype Construct (CPC), which will be deliverable by the end of Phase I. Deliverable will also include a device development and testing plan for phase II, to include drafts of research protocols required for animal and possible human testing. PHASE II: Phase II will focus on the implementation of animal studies and to answer the question: What is the safety and efficacy profile of the Cranioplasty Construct Prototype among mammals? A related question of whether tissue ingrowth of an embedded cranioplasty implant will impede its migration during the process of cerebral edema resolution, will be answered and addressed in this Phase. The performer will implement a TBI animal survival model to approximate the known 3-month period of healing bone and will document bone growth in the post-Cranioplasty test animal survivor through serial CT with 3D Bone reconstructed imaging. Versions of currently used Cranioplasty materials (Polymethyl methacrylate, Titanium) using the prototype design will be compared and analyzed. The performer will also interact with FDA to develop a regulatory compliance plan. The performer will also develop a rational commercialization plan for addressing both the military and civilian markets. The performer will also deliver a refined Beta-prototype of the Cranioplasty Construct and system characterization data to military subject matter experts by the conclusion of Phase II. The performer will also apply for a Humanitarian Device Exempt (HDE) status from the FDA and submit a study protocol to the Walter Reed National Military Medical Center (WRNMMC) IRB for selected Head Injury subjects requiring Decompressive Craniectomy whose condition will not tolerate a second-staged Cranioplasty. Human subjects approval will also be required from the US Army Medical Research and Materiel Command"s Office of Research Protections. PHASE III DUAL USE APPLICATIONS: The further development of the Phase II-developed Beta Cranioplasty prototype will be extended to clinical testing in Phase III. The performer working with industrial partner(s) and/or industry-related funding, will seek out collaborations with neurosurgical institutions both in civilian and military sectors to consolidate outcome studies using the Cranioplasty Prototype in statistically powerful numbers of patients. The preliminary outcomes for prior patient recruitment under the FDA and IRB-approved HDE status will be documented and published. The performer will deliver a plan on how FDA approval will be achieved utilizing current Good Manufacturing Practices (cGMP). Quality Management and device applications will be completed and executed. In the military sphere, the prototype will be made available for Role 2/3 (Forward Surgical Team/Combat Support Hospital) and upward-Medical Treatment Facilities. Deliverables will also include clear, concise and standardized brochures and device guidelines that can be reliably followed by at least a minimally trained healthcare provider at the level of medic/operating room technician and above. REFERENCES: 1. Bell RS, Mossop CM, Dirks MS, Stephens FL, Mulligan L, Ecker R, Neal CJ, Kumar A, Tigno T, Armonda RA,"Early Decompressive Craniectomy for Severe Penetrating and Closed Head Injury During Wartime", Neurosurgical Focus 28:5, May 2010 2. Bell R, Armonda RA,"Severe Traumatic Brain Injury: Evolution and Current Surgical Management", ePublication, Medscape, June, 2008 3. Granthan E, Landis H,"Cranioplasty and the post-traumatic syndrome."J Neurosurg 5:19-22, 1947 4. Yamaura A, Makino H,"Neurological Deficits in the Presence of the Sinking Flap following Decompressive Craniectomy."Neurol Med Chir 17:43-53, 1977 5. Dujovny M, Agner C, Aviles A."Syndrome of the Trephined: Theory and Facts", Crit Rev Neurosurg 9:271-278, 1999. 6. Rish BL, Dillon JD, Meirowsky AM, Caveness WF, Mohr JP, Kistler JP, et al.,"Cranioplasty: A Review of 1030 Cases of Penetrating Head Injury", Neurosurgery 4:381-385, 1979 7. Tigno TA, Armonda RA,"Scientific Reports and Accomplishments for Cranioplasty for the Syndrome of the Trephined", Part I, 2012: https: // reports/ 8. Cheng YK, Weng HH, Yang JT, Lee MH, Wang TC, Chang CN,"Factors Affecting Graft infection After Cranioplasty", J Clin Neurosci 15:1115-1119, 2008 9. Carvi Y, Nievas MN, Hollerhage HG,"Early Combined Cranioplasty and Programmable Shunt in Patients with Skull Bone Defects and CSF Circulation Disorders", Neurol Res 28:139-144, 2006 10. Liang W, Xiaofeng Y, Weiguo L, Gang S, Xuesheng Z, Fei C, et al.,"Cranioplasty of Large Cranial Defect at an Early Stage After Decompressive Craniectomy Performed for Severe Head Trauma", J Craniofac Surg 18:526-532, 2007 11. Gooch MR, Gin GE, Kenning TJ,"Complications of Cranioplasty Following Decompressive Craniectomy: Analysis of 62 Cases", Neurosurg Focus 26 (6):E9, 2009 12. Korinek AM,"Risk Factors for Neurosurgical Site Infections After Craniotomy: A Prospective Multicenter Study of 1944 Patients. The French Study Group of Neurosurgical Infections, the SEHP and the C-CLIN Paris-Nord. Service Epidemiologie Hygiene et Prevention."Neurosurgery 41:1073-1079, 1997 13. Stephens FI., Mossop CM, Bell RS, Tigno TA, Rosner MK, Kumar A, Moores L, Armonda RA,"Cranioplasty Complications following Wartime Decompressive Craniectomy", Neurosurgical Focus/Journal of Neurosurgery, Volume 28, Number 5, May 2010 14. Matsuno, A., H. Tanaka, et al.,"Analyses of the factors influencing bone graft infection after delayed cranioplasty."Acta Neurochir (Wien) 148(5): 535-40; discussion 540, 2006 15. Mokri B,"The Monro-Kellie Hypothesis: Applications in CSF Volume Depletion."Neurology 56(12): 1746-8, 2001
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