Arthur Adolfo Nicolato

Human Placenta Aneurysm Model for Training Neurosurgeons in Vascular Microsurgery

BACKGROUND: Neurosurgery, a demanding specialty, involves many microsurgical procedures that require complex skills, including open surgical treatment of intracranial aneurysms. Simulation or practice models may be useful for acquiring these skills before trainees perform surgery on human patients. OBJECTIVE: To describe a human placenta model for the creation and clipping of aneurysms. METHODS: Placental vessels from 40 human placentas that were dimensionally comparable to the sizes of appropriate cerebral vessels were isolated to create aneurysms of different shapes. The placentas were then prepared for vascular microsurgery exercises. Sylvian fissure--like dissection technique and clipping of large- and small-necked aneurysms were practiced on human placentas with and without pulsatile flow. A surgical field designed to resemble a real craniotomy was reproduced in the model. RESULTS: The human placenta has a plethora of vessels that are of the proper dimensions to allow the creation of aneurysms with dome and neck dimensions similar to those of human saccular and fusiform cerebral aneurysms. These anatomic scenarios allowed aneurysm inspection, manipulation, and clipping practice. Technical microsurgical procedures include simulation of sylvian fissure dissection, unruptured aneurysm clipping, ruptured aneurysm clipping, and wrapping; all were reproduced with high fidelity to the haptics of live human surgery. Skill-training exercises realistically reproduced aneurysm clipping. CONCLUSION: Human placenta provides an inexpensive, widely available, convenient biological tissue that can be used to create models of cerebral aneurysms of different morphologies. Neurosurgical trainees may benefit from the preoperative use of a realistic model to gain familiarity and practice with critical surgical techniques for treating aneurysms.

Face, Content, and Construct Validity of Brain Tumor Microsurgery Simulation Using a Human Placenta Model

BACKGROUND: Brain tumors are complex 3-dimensional lesions. Their resection involves training and the use of the multiple microsurgical techniques available for removal. Simulation models, with haptic and visual realism, may be useful for improving the bimanual technical skills of neurosurgical residents and neurosurgeons, potentially decreasing surgical errors and thus improving patient outcomes. OBJECTIVE: To describe and assess an ex vivo placental model for brain tumor microsurgery using a simulation tool in neurosurgical psychomotor teaching and assessment. METHODS: Sixteen human placentas were used in this research project. Intravascular blood remnants were removed by continuous saline solution irrigation of the 2 placental arteries and placental vein. Brain tumors were simulated using silicone injections in the placental stroma. Eight neurosurgeons and 8 neurosurgical residents carried out the resection of simulated tumors using the same surgical instruments and bimanual microsurgical techniques used to perform human brain tumor operations. Face and content validity was assessed using a subjective evaluation based on a 5-point Likert scale. Construct validity was assessed by analyzing the surgical performance of the neurosurgeon and resident groups. RESULTS: The placenta model simulated brain tumor surgical procedures with high fidelity. Results showed face and content validity. Construct validity was demonstrated by statistically different surgical performances among the evaluated groups. CONCLUSION: Human placentas are useful haptic models to simulate brain tumor microsurgical removal. Results using this model demonstrate face, content, and construct validity. ABBREVIATION: VR, virtual reality

Face, content, and construct validity of human placenta as a haptic training tool in neurointerventional surgery

OBJECT The development of neurointerventional treatments of central nervous system disorders has resulted in the need for adequate training environments for novice interventionalists. Virtual simulators offer anatomical definition but lack adequate tactile feedback. Animal models, which provide more lifelike training, require an appropriate infrastructure base. The authors describe a training model for neurointerventional procedures using the human placenta (HP), which affords haptic training with significantly fewer resource requirements, and discuss its validation. METHODS Twelve HPs were prepared for simulated endovascular procedures. Training exercises performed by interventional neuroradiologists and novice fellows were placental angiography, stent placement, aneurysm coiling, and intravascular liquid embolic agent injection. RESULTS The endovascular training exercises proposed can be easily reproduced in the HP. Face, content, and construct validity were assessed by 6 neurointerventional radiologists and 6 novice fellows in interventional radiology. CONCLUSIONS The use of HP provides an inexpensive training model for the training of neurointerventionalists. Preliminary validation results show that this simulation model has face and content validity and has demonstrated construct validity for the interventions assessed in this study.

Transitory somatoparaphrenia associated with a left frontoparietal meningioma

The term somatoparaphrenia has been used to describe delusional beliefs involving the left side of the body in patients with right brain lesions [4, 12]. Somatoparaphrenia patients complain of a feeling of strangeness affecting the contralateral body parts and present a delusional belief that the affected body parts belong to someone else. Patients may also believe the limbs of another person belong to them [12]. A 62-year-old right-handed woman presented with a history of headache and vomiting lasting a few days. A computed tomography scan showed a left frontoparietal lesion surrounded by edema (Fig. 1). She was started on dexametasone treatment and showed improvement of symptoms. There was no previous history of neurologic or psychiatric symptoms. On neurologic examination, the patient had intact temporal and spatial orientation, mild proximal weakness in her right arm and leg, tactile and pain hypoesthesia in the right half of her body and impaired discrimination of two points. No impairment of proprioception or vibration sense was observed. She was able to point to all parts of her body and the examiner’s body, showing no signs of astereoagnosia, finger agnosia, agraphia, alexia or impairment of visual fields. Right–left disorientation and primary acalculia were detected. Line bisection tasks were performed correctly as were drawings to test visuospatial neglect. No impairment of spontaneous movements of her right arm was observed and she was able to reach and use objects in her right space with her right hand. She reported a feeling of strangeness involving her right upper limb and stated that her limb did not belong to her. Additionally, she mistook her sister’s left upper limb as her own, denying that she was mistaken despite demonstrations proving the contrary. No abnormal movement involving her affected limb was observed. Complete resection of the lesion was performed. Five days after neurosurgery, she no longer denied ownership of her right limb although the signs associated with left parietal dysfunction remained. Histopathologic diagnosis was a meningothelial meningioma. Somatoparaphrenia must be differentiated from asomatognosia, which is defined as a lack of awareness of affected parts of the body associated with agnosia. Patients generally complain that their limbs are missing or imperceptible to them [4, 12]. This distinction, however, is not clear. Some authors describe somatoparaphrenia as a type of asomatognosia and use the term to describe all disorders of bodily awareness [4, 6, 7]. Another differential diagnosis is the alien hand syndrome, characterized by involuntary motor activities sometimes associated with a feeling of strangeness in the affected limb [1, 2]. In these cases, patients fail to recognize their left hand when it is touched by their right hand in the absence of visual confirmation [3]. Other related disorders such as autotopagnosia and motor neglect were ruled out by neurologic evaluation in our patient [8, 10]. R. Beato (&) Departamento de Clı́nica Médica, Faculdade de Medicina da UFMG, Avenida Alfredo Balena, 190-30130-100, Belo Horizonte, MG, Brazil e-mail: rogbeato@uol.com.br

A new expansive two-open-doors laminoplasty for multilevel cervical spondylotic myelopathy: technical report and follow-up results

UNLABELLED The laminoplasty technique was devised by Hirabayashi in 1978 for patients diagnosed with multilevel cervical spondylotic myelopathy. OBJECTIVE To describe an easy modification of Hirabayashis method and present the clinical and radiological results from a five-year follow-up study. METHOD AND RESULTS Eighty patients had 5 levels of decompression (C3-C7), 3 patients had 6 levels of decompression (C2-T1) and 3 patients had 4 levels of decompression (C3-C6). Foraminotomies were performed in 23 cases (27%). Following Nurick`s scale, 76 patients (88%) improved, 9 (11%) had the same Nurick grade, and one patient worsened and was advised to undergo another surgical procedure. No deaths were observed. The mean surgery time was 122 min. Radiographic evaluation showed an increase in the mean sagittal diameter from 11.2 mm at pretreatment to 17.3 mm post surgery. There was no significant difference between pretreatment and post-surgery C2-C7 angles. CONCLUSIONS This two-open-doors laminoplasty technique is safe, easy and effective and can be used as an alternative treatment for cases of multilevel cervical spondylotic myelopathy without instability.

Comparative morphometric study of the sigmoid sinus sulcus and the jugular foramen

OBJECTIVE To compare the right and left sides of the same skulls as far as the described landmarks are concerned, and establish the craniometric differences between them. METHOD We carried out measurements in 50 adult dry human skulls comparing both sides. RESULTS The sigmoid sinus width at the sinodural angle level was larger on the right side in 78% of the cases and at the level of the digastric notch in 72%. The jugular foramen width was also larger on the right side in 84% of the cases. The sigmoid sinus distance at the level of the digastric notch was larger on the right side in 64% of the cases, and the sigmoid sinus distance at the level of the digastric notch to the jugular foramen was larger on the right side in 70% of the cases. CONCLUSION Significant craniometric differences were found between both sides of the same skulls.

Evaluation of the trajectory of the bicortical screws in relation to the internal carotid artery, in fixation by the harms and melcher technique: an experimental study in cadavers

OBJECTIVE: The objective of this study is to study the relationship between bicortical screws and the internal carotid artery, in anatomical body parts, in screw fixation by the Harms and Melcher technique. METHODS: Our sample consisted of five cadavers. RESULTS: The results were as follows: the average shortest distance between the outlet of the screw and the medial edge of the right internal carotid artery was 11.55 mm (range 10.05 to 14.23 mm), while on the left side, the average was 7.50 mm (ranging from 2.75 to 12.42 mm). The average shortest distance between the posterior edge of the internal carotid artery and the anterior cortical C1 lateral mass on the right was 4.24 mm (ranging from 2.08 to 7.48 mm), while the left side, the average was 2.98 mm (ranging from 1.83 to 3.83 mm). CONCLUSION: The results are consistent with similar studies in the literature that emphasize the need for a careful assessment of images of anatomical position of the internal carotid artery prior to the use of bicortical screws in the C1 lateral mass by posterior access.OBJETIVO: O objetivo deste trabalho e estudar, em pecas anatomicas; a relacao entre os parafusos bicorticais pela tecnica de Harms e Melcher e a arteria carotida interna. METODOS: Nossa amostra consiste em cinco cadaveres. RESULTADOS: Os resultados encontrados foram: a media da menor distância entre o orificio de saida do parafuso e a borda medial da arteria carotida interna direita foi de 11,55 mm (com variacao de 10,05 a 14,23 mm), enquanto do lado esquerdo a media foi de 7,50 mm (variando de 2,75 a 12,42 mm). A media da menor distância entre a borda posterior da arteria carotida interna e a cortical anterior da massa lateral de C1 a direita foi de 4,24 mm (variando de 2,08 a 7,48 mm), enquanto do lado esquerdo a media obtida foi de 2,98 mm (com variacao de 1,83 a 3,83 mm). CONCLUSAO: Os resultados encontrados estao de acordo com os estudos similares existentes na literatura que enfatizam a necessidade de uma avaliacao imaginologica criteriosa da posicao anatomica da arteria carotida interna antes da utilizacao de parafusos bicorticais na massa lateral de C1 por via posterior.

Evaluación de la trayectoria de los tornillos bicorticales en la técnica de harms y melcher en relación con la arteria carótida interna: un estudio experimental en cadáveres

OBJECTIVE: The objective of this study is to study the relationship between bicortical screws and the internal carotid artery, in anatomical body parts, in screw fixation by the Harms and Melcher technique. METHODS: Our sample consisted of five cadavers. RESULTS: The results were as follows: the average shortest distance between the outlet of the screw and the medial edge of the right internal carotid artery was 11.55 mm (range 10.05 to 14.23 mm), while on the left side, the average was 7.50 mm (ranging from 2.75 to 12.42 mm). The average shortest distance between the posterior edge of the internal carotid artery and the anterior cortical C1 lateral mass on the right was 4.24 mm (ranging from 2.08 to 7.48 mm), while the left side, the average was 2.98 mm (ranging from 1.83 to 3.83 mm). CONCLUSION: The results are consistent with similar studies in the literature that emphasize the need for a careful assessment of images of anatomical position of the internal carotid artery prior to the use of bicortical screws in the C1 lateral mass by posterior access.OBJETIVO: O objetivo deste trabalho e estudar, em pecas anatomicas; a relacao entre os parafusos bicorticais pela tecnica de Harms e Melcher e a arteria carotida interna. METODOS: Nossa amostra consiste em cinco cadaveres. RESULTADOS: Os resultados encontrados foram: a media da menor distância entre o orificio de saida do parafuso e a borda medial da arteria carotida interna direita foi de 11,55 mm (com variacao de 10,05 a 14,23 mm), enquanto do lado esquerdo a media foi de 7,50 mm (variando de 2,75 a 12,42 mm). A media da menor distância entre a borda posterior da arteria carotida interna e a cortical anterior da massa lateral de C1 a direita foi de 4,24 mm (variando de 2,08 a 7,48 mm), enquanto do lado esquerdo a media obtida foi de 2,98 mm (com variacao de 1,83 a 3,83 mm). CONCLUSAO: Os resultados encontrados estao de acordo com os estudos similares existentes na literatura que enfatizam a necessidade de uma avaliacao imaginologica criteriosa da posicao anatomica da arteria carotida interna antes da utilizacao de parafusos bicorticais na massa lateral de C1 por via posterior.

Avaliação da trajetória dos parafusos bicorticais pela técnica de harms e melcher em relação à artéria carótida interna: estudo experimental em cadáveres

OBJECTIVE: The objective of this study is to study the relationship between bicortical screws and the internal carotid artery, in anatomical body parts, in screw fixation by the Harms and Melcher technique. METHODS: Our sample consisted of five cadavers. RESULTS: The results were as follows: the average shortest distance between the outlet of the screw and the medial edge of the right internal carotid artery was 11.55 mm (range 10.05 to 14.23 mm), while on the left side, the average was 7.50 mm (ranging from 2.75 to 12.42 mm). The average shortest distance between the posterior edge of the internal carotid artery and the anterior cortical C1 lateral mass on the right was 4.24 mm (ranging from 2.08 to 7.48 mm), while the left side, the average was 2.98 mm (ranging from 1.83 to 3.83 mm). CONCLUSION: The results are consistent with similar studies in the literature that emphasize the need for a careful assessment of images of anatomical position of the internal carotid artery prior to the use of bicortical screws in the C1 lateral mass by posterior access.OBJETIVO: O objetivo deste trabalho e estudar, em pecas anatomicas; a relacao entre os parafusos bicorticais pela tecnica de Harms e Melcher e a arteria carotida interna. METODOS: Nossa amostra consiste em cinco cadaveres. RESULTADOS: Os resultados encontrados foram: a media da menor distância entre o orificio de saida do parafuso e a borda medial da arteria carotida interna direita foi de 11,55 mm (com variacao de 10,05 a 14,23 mm), enquanto do lado esquerdo a media foi de 7,50 mm (variando de 2,75 a 12,42 mm). A media da menor distância entre a borda posterior da arteria carotida interna e a cortical anterior da massa lateral de C1 a direita foi de 4,24 mm (variando de 2,08 a 7,48 mm), enquanto do lado esquerdo a media obtida foi de 2,98 mm (com variacao de 1,83 a 3,83 mm). CONCLUSAO: Os resultados encontrados estao de acordo com os estudos similares existentes na literatura que enfatizam a necessidade de uma avaliacao imaginologica criteriosa da posicao anatomica da arteria carotida interna antes da utilizacao de parafusos bicorticais na massa lateral de C1 por via posterior.