Polymethyl Methacrylate Cranioplasty Is an Effective Ultrasound Window to Explore Intracranial Structures: Preliminary Experience and Future Perspectives.

OBJECTIVE: To evaluate the feasibility of transcranial sonography in patients harboring polymethylmethacrylate cranioplasties (PMMA-CP) and explore whether this material is a valid sonic window to explore intracerebral structures. METHODS: In 6 patients, we performed transcranial sonography (TCS), using the PMMA-CP as sonic window. To test the reliability of ultrasound images, we collected several quantitative and qualitative measurements of intracranial structures and compared these sonographic images with standard computed tomography (CT) scan images. RESULTS: We found that PMMA-CP is a very good sonic window and allowed us to obtain very good quality echographic images of intracranial structures, as shown by the comparison of measurements with CT scan, which were very reliable. The main drawback was related to the shape (i.e., the curvature) of the cranial flap, which hindered the ultrasound probe from correctly adhering to the scalp. CONCLUSIONS: Although limited by the restricted number of cases, this preliminary experience represents the first available data about the serial use of TCS using PMMA-CP as window. These results open the path to the routine use of TCS to longitudinally control patients already harboring PMMA-CP. More, we here discuss its potential role in globally reducing the number of follow-up CT and magnetic resonance imaging scans required in different type of patients and pathologies.

In-situ Cranioplasty after Microvascular Decompression: A Technical Note.

Cranioplasty is not only performed for cosmetic reasons but also for physiological requirements to balance the cerebral hemodynamics and to protect the brain from external traumas. Methyl methacrylate is one of the most preferred materials for cranioplasty. It is usually prepared out of the surgical site and therefore modelling of the cranioplasty material to fit the bone defect is sometimes difficult. In this technical note, we present our new technique of cranioplasty with methyl methacrylate in which the material is prepared on site of the bone defect and very easily shaped. Fixation materials are not needed. This technique is especially suitable for posterior fossa surgeries after craniectomy.

Intratumoral gene therapy versus intravenous gene therapy for distant metastasis control with 2-diethylaminoethyl-dextran methyl methacrylate copolymer non-viral vector-p53.

Lung cancer still remains to be challenged by novel treatment modalities. Novel locally targeted routes of administration are a methodology to enhance treatment and reduce side effects. Intratumoral gene therapy is a method for local treatment and could be used either in early-stage lung cancer before surgery or at advanced stages as palliative care. Novel non-viral vectors are also in demand for efficient gene transfection to target local cancer tissue and at the same time protect the normal tissue. In the current study, C57BL/6 mice were divided into three groups: (a) control, (b) intravenous and (c) intatumoral gene therapy. The novel 2-Diethylaminoethyl-Dextran Methyl Methacrylate Copolymer Non-Viral Vector (Ryujyu Science Corporation) was conjugated with plasmid pSicop53 from the company Addgene for the first time. The aim of the study was to evaluate the safety and efficacy of targeted gene therapy in a Lewis lung cancer model. Indeed, although the pharmacokinetics of the different administration modalities differs, the intratumoral administration presented increased survival and decreased distant metastasis. Intratumoral gene therapy could be considered as an efficient local therapy for lung cancer.

A methyl methacrylate-HEMA-CL(n) copolymerization investigation: from kinetics to bioapplications.

The radical copolymerization kinetics of methyl methacrylate (MMA) and poly-ϵ-caprolactone macromonomer functionalized with a vinyl end group (HEMA-CL(n)) is studied using a pulsed-laser technique. The reactivity ratios for this system are near unity, while a linear relationship between k(p,cop), the copolymer-averaged propagation rate coefficient, and the composition of macromonomer in the feed (0-80 wt% range) is determined. At 50 wt% macromonomer in the feed, a 1.67 ± 0.02 and 1.64 ± 0.06 increase in k(p,cop)/k(p,MMA) is determined for HEMA-CL3 and HEMA-CL2, respectively. These macromonomers are adopted to synthesize nanoparticles (NPs) in the range of 100-150 nm through batch emulsion free radical polymerization (BEP) to produce partially degradable drug delivery carriers. The produced NPs are tested in 4T1 cell line and show excellent characteristics as carriers: they do not affect cell proliferation, and a relevant number of NPs, thousands per cell, are internalized.

2-diethylaminoethyl-dextran methyl methacrylate copolymer nonviral vector: still a long way toward the safety of aerosol gene therapy.

Revealing the lung tumor genome has directed the current treatment strategies toward targeted therapy. First line treatments targeting the genome of lung tumor cells have been approved and are on the market. However, they are limited by the small number of patients with the current investigated genetic mutations. Novel treatment administration modalities have been also investigated in an effort to increase the local drug deposition and disease control. In the current study, we investigated the safety of the new nonviral vector 2-diethylaminoethyl-dextran methyl methacrylate copolymer (DDMC; Ryujyu Science), which belongs to the 2-diethylaminoethyl-dextran family by aerosol administration. Thirty male BALBC mice, 2 month old, were included and divided into three groups. However, pathological findings indicated severe emphysema within three aerosol sessions. In addition, the CytoViva technique was applied for the first time to display the nonviral particles within the pulmonary tissue and emphysema lesions, and a spectral library of the nonviral vector was also established. Although our results in BALBC mice prevented us from further investigation of the DDMC nonviral vector as a vehicle for gene therapy, further investigation in animals with larger airways is warranted to properly evaluate the safety of the vector.

Primary Ewing's sarcoma of the skull: radical resection and immediate cranioplasty after chemotherapy. A technical note.

PURPOSE: The current standard treatment of Ewing's sarcoma is chemotherapy followed by surgery, making an immediate cranial reconstruction in a one-step surgical procedure possible. METHODS: We describe the technique used to repair a cranial defect after the resection of a primary Ewing's sarcoma of the skull in a one-step surgical procedure. RESULTS: Bone repair with a custom-made cranioplasty immediately after resection of a primary Ewing's sarcoma of the skull avoids deformities and late complications associated with reconstructive surgery after radiotherapy and not interfere with radiotherapy and neither with follow-up. CONCLUSION: A one-step surgical procedure after chemotherapy for primary Ewing's sarcoma of the skull could be safer, less aggressive and more radical; avoiding deformities and late complications.

Percutaneous vertebroplasty for vertebral compression fractures with intravertebral cleft: cement injection under vacuum aspiration.

PURPOSE: To evaluate the efficacy of cement injection under vacuum aspiration (CIVAS) of cleft contents in percutaneous vertebroplasty for osteoporotic vertebral compression fractures with an intravertebral cleft. MATERIALS AND METHODS: From April 2008 to October 2010, vertebroplasty for single-level osteoporotic vertebral compression fractures with clefts was performed in 34 patients (seven women, 27 men; mean age, 77 y) with CIVAS and in 41 patients (three women, 38 men; mean age, 77 y) by conventional injection (control group). In this retrospective study, the cement volume, cement ratio, visual analog scale (VAS) pain score, and incidences of leakage, new vertebral compression fracture, and nonhealing were compared between groups. Vertebral height changes in the CIVAS group were also evaluated. RESULTS: There were significant decreases in VAS scores in both groups (P < .001). There were no significant differences in complications between groups (cement leakage, P = .70; new vertebral compression fracture, P = .17; nonhealing, P = .086). Vertebral height was significantly decreased by vacuum aspiration and increased by cement injection (P < .001). The mean cement volume was significantly higher (P = .0057) in the CIVAS group (4.87 mL) than in the control group (3.58 mL). Cement filling was achieved more sufficiently in the CIVAS group (P = .014). CONCLUSIONS: The CIVAS method is feasible and appears to improve cleft filling in the treatment of single-level vertebral compression fractures with a cleft, compared with conventional cement injection.

Temporal augmentation with methyl methacrylate.

Concavity in the temporal area reflects a deficiency in the bulk of the temporalis muscle or overlying temporal fat pad. It may be a reflection of senescence, low body fat, exaggerated adjacent skeletal or soft-tissue contours, idiopathic progressive atrophy, or postsurgical deformities. The authors describe the application of methyl methacrylate (MMA) to fill depressions in the temporal area. In instances in which no previous surgery has been performed or when the temporal area has served as a dissection plane for surgery in adjacent areas (eg, a subperiosteal facelift), the implant material is placed beneath the temporal muscle through a limited incision in the hair-bearing scalp. When previous reconstructive surgery has been performed in the temporal area, the area of depression is accessed through existing surgical incision scars to place MMA over the temporal muscle. These operative techniques have been reliable, durable, and relatively free of complications.

A biodegradable antibiotic delivery system based on poly-(trimethylene carbonate) for the treatment of osteomyelitis.

BACKGROUND AND PURPOSE: Many investigations on biodegradable materials acting as an antibiotic carrier for local drug delivery are based on poly(lactide). However, the use of poly(lactide) implants in bone has been disputed because of poor bone regeneration at the site of implantation. Poly(trimethylene carbonate) (PTMC) is an enzymatically degradable polymer that does not produce acidic degradation products. We explored the suitability of PTMC as an antibiotic releasing polymer for the local treatment of osteomyelitis. METHODS: This study addressed 2 separate attributes of PTMC: (1) the release kinetics of gentamicin-loaded PTMC and (2) its behavior in inhibiting biofilm formation. Both of these characteristics were compared with those of commercially available gentamicin-loaded poly(methylmethacrylate) (PMMA) beads, which are commonly used in the local treatment of osteomyelitis. RESULTS: In a lipase solution that mimics the in vivo situation, PTMC discs with gentamicin incorporated were degraded by surface erosion and released 60% of the gentamicin within 14 days. This is similar to the gentamicin release from clinically used PMMA beads. Moreover, biofilm formation by Staphylococcus aureus was inhibited by approximately 80% over at least 14 days in the presence of gentamicin-loaded PTMC discs. This is similar to the effect of gentamicin-loaded PMMA beads. In the absence of the lipase, surface erosion of PTMC discs did not occur and gentamicin release and biofilm inhibition were limited. INTERPRETATION: Since gentamicin-loaded PTMC discs show antibiotic release characteristics and biofilm inhibition characteristics similar to those of gentamicin-loaded PMMA beads, PTMC appears to be a promising biodegradable carrier in the local treatment of osteomyelitis.

Methyl methacrylate activates the Gsta1 promoter.

Residual monomers in resin-based biomaterials cause cytotoxicity. We previously showed that methyl methacrylate (MMA) induced mRNA expression of the glutathione S-transferase alpha 1 gene (Gsta1) located downstream of the cis-acting anti-oxidant responsive element (ARE). Herein, we tested the hypothesis that MMA activated the Gsta1 promoter through the ARE. HepG2 cells were transfected with a luciferase reporter vector containing the ARE and the Gsta1 promoter (-990 to +46 bp) and cultured for 12 hrs with MMA (initial concentration, 10 mM). Analysis of the expressed luciferase activity indicated that MMA activated the promoter 2.6-fold. MMA (from 1 to 30 mM) dose-dependently increased the promoter activity, which reached a plateau between 6 and 12 hrs. In HepG2 cells transfected with a reporter vector containing 2 AREs and a TATA-like promoter, 10 mM MMA increased the reporter expression 2.8-fold. These results suggest that MMA increases Gsta1 transcription through ARE-mediated promoter activation.

Acute respiratory arrest following partial suboccipital cranioplasty for cerebellar ptosis from Chiari malformation decompression.

Cerebellar ptosis is a rare complication following Chiari malformation decompression, and generally is the result of a very large suboccipital craniectomy. This can lead to the descent of the cerebellum through the craniectomy defect, which in turn may result in cerebellar herniation through the surgical defect as well as the reestablishment of contact between the cerebellar tonsils and the brainstem. In addition, dorsal adherence of the herniated cerebellum to the dura mater or dural patch and an associated obstruction of cerebrospinal fluid flow at the cervicomedullary junction may ensue. Such a result is not desirable, in that it reproduces or mimics the pathoanatomical relationships that existed prior to the surgical decompression.

Prophylactic injection of methylmetacrylate in vertebrae located between two previously cemented levels does not prevent a subsequent compression fracture in a patient with bone fragility.

A 68-year-old woman with a fragility fracture of the fourth lumbar vertebra was treated with a first vertebroplasty using methylmetacrylate with an initial good pain relief. Early painful recurrent vertebral fractures led to iterative vertebroplasties. Furthermore prophylactic treatment with methylmetacrylate of a non-fractured vertebra located between two previously injected ones did not prevent its collapse. This case report underlines the lack of a clear evaluation benefit/risk ratio of these procedures in patients with non-malignant bone fragility.

Percutaneous sacroplasty using CT fluoroscopy.

Sacral insufficiency fractures frequently cause significant pain and limit activities of daily living in patients with osteoporosis. Percutaneous vertebroplasty is a common procedure to alleviate the pain associated with thoracic and lumbar vertebral compression fractures. The sacral percutaneous vertebroplasty procedure (sacroplasty) has recently been introduced as an alternative to medical management of osteoporotic sacral insufficiency fractures. We describe our CT fluoroscopy technique in performing percutaneous sacroplasty.

Chest wall resection and reconstruction: analysis of 11 cases after methylmethacrylate reconstruction.

BACKGROUND: Patients with extensive resection of the chest wall, followed by reconstruction with methylmethacrylate and double prolene mesh in the form of "sandwich" prosthesis. Substitutes were assessed prospectively as chest wall defects continue to present a complicated treatment scenario for thoracic and reconstructive surgeons. OBJECTIVES: To evaluate the results of eleven patients who underwent chest wall resection and reconstruction. MATERIALS AND METHODS: Eleven patients were prospectively reviewed who underwent chest wall resection and reconstruction at National Cancer Institute Cairo University. Among them, 7 were male and 4 female. The mean age was 34.5 (SDV +/- 19.8) years. The indications for resection were primary chest wall tumor in 7 patients (63.7%), recurrence of breast cancer 2 (18.2%), lung cancer with invasion of chest wall 1 (9.1%) and pleuroblastoma 1 (9.1%). RESULTS: The mean number of rib resected was 4.18 +/- 1.16 ribs (3-6). Concomitant resection was done in 6 patients; including lung resection 2, partial resection of diaphragm 2, lateral clavicle with forequarter amputation 1 and partial sternectomy 1. All patients underwent skeletal reconstruction (SR) with methylmethacrylate and double prolene mesh in the form of"sandwich" prosthesis. Simultaneous SR and soft tissue reconstruction (STR) were performed in 7 patients 63.7%. Five patients (45.5%) developed postoperative complications with no perioperative mortality. Follow-up was carried out for a mean period of 18.7 months (11-36). Three patients developed relapse (27.3%), local recurrence in two cases and bone metastases in one case. CONCLUSIONS: Chest wall resection followed immediately by reconstruction utilizing synthetic mesh with a filler of methylmethacrylate with or without local or pedicled muscle flaps can be performed as a safe, effective one-stage surgical procedure for major chest wall defects which prevents paradoxical movement of chest wall and overcomes deformity.

Complications of percutaneous vertebroplasty and their prevention.

Vertebroplasty is an efficient treatment of vertebral collapses of malignant or benign origin but also carries a risk of complications. Cement extravasation is a frequent occurrence in vertebroplasty. It is well tolerated in the large majority of cases but is also the main source of complications especially nerve root compression in case of cement leakage into the intervertebral foramen and pulmonary embolism of cement complicating venous cement leakage. Rate of these complications are much higher in malignant than in osteoporotic collapses. The risk of neurological complication also increases at the cervical level. In addition, incidence of new vertebral fractures in adjacent vertebrae may be increased by vertebroplasty. General reactions possibly due to a reflex reaction to intramedullary bone injection and fat embolism may also occur. This article reviews the safety measures to reduce the risk of cement extravasation including high quality permanent radiological guidance enabling early detection of cement extravasation, use of conscious sedation, bilateral transpedicular approach at the thoracic and lumbar levels, careful selection of the bone penetration site in order to make a single vertebral needle path, careful needle placement to avoid the risk of cortical breakthrough, use of a well-opacified and refrigerated cement with a toothpaste consistency.

Ex vivo measurement of intravertebral pressure during vertebroplasty.

STUDY DESIGN: Ex vivo biomechanical study using cadaver vertebral bodies. OBJECTIVE.: To measure the increase in internal vertebral body pressure from cement injection during vertebroplasty. SUMMARY OF BACKGROUND DATA: Theoretically, the increased force required to inject polymerizing (viscous) cement into a vertebral body during vertebroplasty could produce a concomitant increase in intravertebral pressure and cause additional damage to the vertebral body. An alternative means of reducing intravertebral pressure during injection may be needed. METHODS: We placed 11-gauge cannulas bipedicularly in six vertebral bodies from each of two fresh female cadaver spines (one osteoporotic, one normal). One cannula served as the injection route; a manometer was connected to the other. After immersion of the spines in a saline bath, the vertebral bodies were injected with 10 mL of Simplex P cement by depressing the syringe plunger at a rate of 7 mm/sec using a materials testing machine. Static pressure was measured before and after injection. Peak pressure was measured during injection. Maximum pressure elevation was calculated as peak pressure minus initial static pressure. RESULTS: Maximum pressure elevation averaged (+/-SD) 9.4 +/- 8.5 mm Hg and 6.4 +/- 5.0 mm Hg in the osteoporotic and normal spines, respectively. In all cases (9 of 12) in which the pressure measurement system remained patent (i.e., not occluded by cement), postinjection pressure returned to the initial static pressure. CONCLUSION: The increase in intravertebral body pressure from cement injection during vertebroplasty is minimal. Alternative means of reducing intervertebral pressure before injection may not be needed.

Treatment of chronic symptomatic vertebral compression fractures with percutaneous vertebroplasty.

OBJECTIVE: Most fractures treated with percutaneous vertebroplasty are subacute and less than 1 year old. We report our experience treating chronic vertebral fractures with vertebroplasty. MATERIALS AND METHODS: Our database identified 41 patients with symptomatic fractures more than 1 year old. These patients were categorized into subgroups determined by fracture age: 12 months 1 day-24 months (n = 16) or more than 24 months 1 day (n = 25). Changes in pain and mobility for the study group were compared with those in 49 patients with fractures less than 1 year old. RESULTS: Thirty-three (80%) of the 41 patients in the study group had improvement in pain-seven (17%) had complete and 26 (63%) had partial relief. Forty-five (92%) of the 49 control group patients had improvement in pain-24 (49%) had complete and 21 (43%) had partial relief. The number of patients achieving partial or complete relief of pain was not statistically different between groups (p > 0.05), although complete relief was significantly more frequent in the control group (p = 0.002). Twenty patients (49%) in the study group versus 34 patients (69%) in the control group had improved mobility after vertebroplasty (p = 0.047). Patients with fractures 12 months 1 day-24 months old had improvement in mobility similar to that in patients in the control group (p = 0.962). Fractures more than 24 months 1 day old were associated with significantly less improvement in mobility (p = 0.006). CONCLUSION: Most patients with fractures more than 1 year old will experience clinical benefit from vertebroplasty. Complete relief of pain is more likely when less mature fractures are treated.

[Interventional lumbar spine radiology]. / Radiologie interventionnelle du rachis lombaire.

Three different techniques will be discussed. The first procedure is the biopsy of the lumbar vertebra or lumbar intervertebral disc for patients with tumors or infections of the lumbar spine. The different needles that can be used in function of consistency and location of the lesion will be shown. The transpedicular and posterolateral techniques will be described. Cementoplasty for tumors and selected patients with osteoporotic vertebral collapse generates much interest. The transpedicular and posterolateral techniques will be described. Indications and complications, more frequent in patients with tumors, will be reviewed. Finally, foraminal injections of steroids in patients with radicular symptoms secondary to degenerative change will be discussed. Techniques for needle placement will be reviewed. Results from these injections will also be reviewed.