Oculopalpebral prosthesis prototype design using the additive manufacturing technique: A case study.

Three-dimensional (3D) printing technology has advanced for applications in the field of reconstructive surgery. This study reports the application of a comprehensive methodology to obtain an anatomical model, using computed tomography and 3D printing, to treat a patient with cancer who designed a prototype oculopalpebral prosthesis for the reconstruction of the affected area of the face (left eye). A personalized prototype was obtained, which adapted to the face of the person, and improved the aesthetics and quality of life. The applied techniques helped to make definitive prostheses using materials that could be permanent. The training and tests carried out in this study favored the understanding and assimilation of the technology and the possibility of applying it to patients in need of facial prosthetic rehabilitation.

Finite element analysis of a customized implant in PMMA coupled with the cranial bone.

This computational study investigates the effect of the Von Misses stresses and deformations distribution generated by coupling a customized cranial implant with its fixation system for anchoring in the cranial bone of a specific patient. Three simulations were carried out under static loads, in different areas of the implant and during the rest-activity; and another three simulations were considered preset maximum intracranial pressures. Anatomical models were obtained by computed tomography. The design of the device to be implanted was carried out by applying reverse engineering processes, from the corresponding computer-aided design (CAD) model of the bone structure of interest. Likewise, the anchoring system was modeled in detail. Loads were applied at three points on the custom implant. The stress distribution on the artificial plate and the implant-natural bone interface was analyzed. The distribution of the stresses caused by the internal load states on the plate and the anchoring system was also studied. The neurocranial reconstruction with the customized polymethylmethacrylate (PMMA)-based implant and the finite element analysis demonstrated that the fixation and coupling system of the bone-implant interface guarantees adequate protection for the internal structures of the restored area. In addition, the custom-designed and placed implant will not cause non-physiological harm to the patient. Nor will failures occur in the anchoring system.

Grading of moyamoya disease allows stratification for postoperative ischemia in bilateral revascularization surgery.

BACKGROUND: Moyamoya disease (MMD) may be graded based on DSA, the presence of ischemia in MRI and cerebrovascular reserve capacity allowing the prediction of ischemic symptoms in patients. Cerebral ischemia represents a severe complication in revascularization surgery. Focusing on different clinical features of hemodynamic impairment, MMD grading may allow prediction of ischemic complications. It was the aim to analyze whether MMD grading stratifies for ischemic complications in revascularization surgery for MMD. METHOD: In 37 MMD patients a bilateral, standardized, one-staged revascularization approach consisting of STA-MCA bypass/encephalomyosynangiosis (EMS) and single EMS on the contralateral hemisphere was performed. Clinical data including DSA, MRI and rCBF (Xenon-CT) studies were assessed and used for grading MMD. All patients were observed on the ICU for at least 24 h and received CT imaging on the first postoperative day and in case of neurological deterioration. Ischemic complications were analyzed until the day of discharge and at 6-month follow-up. RESULTS: Grading of MMD revealed 11 hemispheres (15 %) as grade I, 33 hemispheres (44 %) as grade II and 30 hemispheres (41 %) as grade III. Eight ischemic complications were observed (11 %). MMD grading demonstrated a significant correlation with ischemic complications: 0 complications in grade I, 3 in grade II (9 %) and 5 in grade III hemispheres (16 %; p < 0.05, Fisher's exact test). CONCLUSIONS: The proposed grading system allows to stratify for ischemic complications in MMD patients that receive bilateral, one-staged revascularization surgery. Future studies will have to investigate its use for predicting ischemic complications in other revascularization strategies for MMD.

Characterization of direct and indirect cerebral revascularization for the treatment of European patients with moyamoya disease.

BACKGROUND: The best revascularization strategy for moyamoya disease (MMD) remains unknown. Our aim was to characterize angiographic revascularization effects of a bilateral standardized revascularization approach, consisting of superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and encephalomyosynangiosis (EMS) on one hemisphere and single EMS on the contralateral hemisphere of each patient, and to compare the effects of both revascularization strategies on cerebral hemodynamics. METHODS: In 30 patients (18 females/12 males, age 8-63 years), standardized revascularization was performed. Digital subtraction angiography was performed preoperatively and at 7 days, 6 months and 12 months postoperatively. STA-MCA and EMS functions were graded I (poor), II (medium) or III (extensive) according to angiographic aspects. In 20 patients, cerebrovascular reserve capacity (CVRC) was assessed pre- and postoperatively (at 12 months) using xenon CT. RESULTS: After 12 months, STA-MCA/EMS function was grade 1 in 40/40%, grade 2 in 27/26%, and grade 3 in 27/10% of hemispheres, respectively. Twelve months after surgery, single EMS showed grade I in 37%, grade II in 27%, and grade III in 20% of hemispheres. Combined revascularization improved CVRC significantly compared to preoperative measurement (preoperative: 16.5 ± 34.6% vs. postoperative: 60.8 ± 64.22%; p < 0.05). Single EMS did not improve CVRC significantly (preoperative: 21.8 ± 35.9% vs. postoperative: 34.8 ± 63.0%; p < 0.05). CONCLUSIONS: Combined and indirect revascularization may be successfully applied in a bilateral standardized approach. STA-MCA/EMS is superior to single EMS in restoring CVRC in adult MMD patients.

Proposal for a new grading of Moyamoya disease in adult patients.

BACKGROUND: Moyamoya disease (MMD) is graded based on digital subtraction angiography (DSA) with limited clinical applications. The aim was to identify clinically relevant parameters that may be used to develop a novel MMD grading system. METHODS: In 40 MMD patients bilateral revascularization surgery was performed. Clinical data including DSA, MRI and regional cerebral blood flow studies were assessed. χ(2) test corrected for dependency of measurements at the same subject and analysis of receiver operating characteristics were used to identify key parameters. Grading system included: DSA (stenosis/occlusion = 1 point; stenosis/occlusion + intracranial compensation = 2 points; stenosis/occlusion + intracranial compensation + extra-intracranial compensation = 3 points), MRI (no sign of ischemia = 0 points; signs of ischemia = 1 point) and cerebrovascular reserve capacity (CVRC > -5% = 0 points; CVRC < -5% = 2 points). MMD grade I referred to 1-2 points, grade II to 3-4 and grade III to 5-6 points. RESULTS: DSA, MRI and CVRC were dependent factors associated with the occurrence of clinical symptoms. Receiver operating characteristics analysis indentified the grading system as superior to each single parameter in predicting clinical symptoms. Fourteen hemispheres were graded as mild (grade I), 35 as moderate (grade II) and 31 as severe (grade III); 21% of grade I, 63% of grade II and 93% of grade III hemispheres were clinically symptomatic. CONCLUSIONS: The proposed grading system allows to stratify for clinical symptomatology in MMD patients. Future studies will have to investigate its value for assessing clinical symptoms and treatment risks.

[Moyamoya disease]. / Enfermedad de moyamoya.

AIMS: To describe the clinical manifestations and to summarise the knowledge currently available about the epidemiology, physiopathology, histopathology, diagnosis and treatment of moyamoya disease. DEVELOPMENT: Moyamoya disease is produced by the spontaneous, progressive occlusion of the circle of Willis with the simultaneous appearance of natural intracranial and extra-intracranial collaterals. Both children and adults can be affected and it is to be found not only in Asia but also in Europe and America, although the frequency is unknown. Its primary lesion is a thickening of the tunica interna in the distal segment of the internal carotids, initially within the anterior portion of the circle of Willis. This results in the appearance of collateral vessels, which are first intracranial (moyamoya vessels) and then extracranial, to offset the critical reduction in regional cerebral blood flow. The most common clinical manifestation is motor-type ischaemic episodes, although it may also be accompanied by intracerebral haemorrhages. It can be diagnosed by means of suitable morphological and functional studies, such as cerebral pan angiography and xenon-CT, in patients with a founded clinical suspicion. Neurosurgical revascularisation is to date the most widely accepted treatment and can bring about a permanent clinical cure. CONCLUSIONS: Moyamoya disease is a rare pathology that can be successfully treated using cerebral revascularisation, provided a timely diagnosis is reached and in indicated patients. Such therapy makes it possible to prevent the repetition of ischaemic events or haemorrhages that usually bring about severe limitations in the individual's personal development.

[Permanent endovascular occlusion of the middle cerebral artery in Wistar rats: a description of surgical approach through the internal carotid artery]. / Oclusión endovascular permanente de la arteria cerebral media en ratas Wistar: descripción del abordaje a través de la arteria carótida interna.

INTRODUCTION: The importance of cerebral ischemia in clinical practice has driven the development of diverse experimental models of its different forms and different methods of producing it have been described. Here we report our experience with the use of the internal carotid artery (ICA) as an access route for the permanent endoluminal occlusion of the middle cerebral artery (MCA) in Wistar rats, and a detailed description of the procedure. AIMS: Our aim at the at the Universidad de Cuenca Research Institute was to establish a standard technique for the constant and repeatable production of a focal cerebral infarct in the MCA territory in Wistar rats. MATERIALS AND METHODS: Using a cervical approach, the ICA was dissected in 20 Wistar rats and, by means of an arteriotomy, a 25 mm long nylon 3-0 or 4-0 filament was introduced until the MCA was obstructed. The infracted area was delimited with 2,3,5-triphenyltetrazolium chloride and its volume was calculated using computer software. RESULTS: Positive results were obtained in 10 cases, the mean volume of the infarct was 488.84 mm3, and the standard error was found to be 63.91 mm3. Subcortical infarcts occurred on three occasions. Two cases presented subarachnoid haemorrhage and two others showed parenchymatous haemorrhages; there were three deaths. CONCLUSIONS: The use of the ICA as an entry point is an effective alternative for the endovascular production of focal cerebral ischemia and the use of a nylon 4-0 filament was more efficient than using a calibre 3-0 filament.

[A report of 62 cerebral aneurysms that were clipped at the Hospital Regional Docente Vicente Corral Moscoso in the city of Cuenca, Ecuador]. / Comunicado de 62 aneurismas cerebrales clipados en el Hospital Regional Docente Vicente Corral Moscoso de la ciudad de Cuenca, Ecuador.

AIMS: The purpose of this study was to establish certain epidemiological characteristics of cerebral aneurysm surgery at the Hospital Regional Docente Vicente Corral Moscoso (HVCM), in the city of Cuenca. PATIENTS AND METHODS: We examined the medical records of the patients who were treated at the HVCM, in Cuenca, over a 14 year period after being diagnosed as suffering from aneurysmal subarachnoid haemorrhage (ASAH), which was confirmed using cerebral arteriography. Patients were catalogued according to age, sex, origin, marital status, the number of months the aneurysm had been ruptured, their Hunt and Hess score on admission, incurrent diseases, habit of smoking, neurological signs on admission, the site of the aneurysm, treatment received, complications, surgery-rupture and admission-surgery time and outcomes when discharged. Only patients who had undergone surgical treatment were considered. RESULTS: There were an average of 6.07 cases of ASAH and 4.7 aneurysm operations a year. Most patients were females from the provinces of Azuay and El Oro; the average age was 45.9 years, and incidence was higher in the months of March-April and August-September. The most common site for presentation was the posterior communicating artery, which occurred in 44% of the cases. The most frequently observed preoperative complications were rebleeding and vasospasm. Surgery was performed on a total of 67 patients and none of them were submitted to early surgery. Operative death rate was 6%. Overall results were optimal in 55.2%. CONCLUSIONS: The therapeutic option offered by our service for this pathology is satisfactory. Indeed, it is similar to that employed in other centres throughout Latin America and has improved over the last few years thanks to the experience that has been acquired in this field.