Two-Stage Pulsatile Human Placenta Model for Microvascular Anastomosis Training in Neurosurgery.

OBJECTIVE: The development of microsurgical skills is crucial for neurosurgical education. The human placenta is a promising model for practicing vascular anastomosis due to its similarities with brain vessels. We propose a 2-stage model for training in extracranial-to-intracranial anastomosis using the placenta. METHODS: Initially, we propose practicing anastomosis in 2 adjacent placentas. Once successful, the procedure advances to a more challenging configuration that employs a 3-dimensionally printed skull with a window simulating a pterional craniotomy. It is positioned an intracranial placenta and an extracranial one, and the latter has a prominent vessel exposed toward the side of the craniotomy. Both placentas have one artery and vein cannulated in the umbilical cord, and we present an artificial placental circulation system for microvascular training that regulates pulsation and hydrodynamic pressure while keeping veins engorged with a pressurized bag. To verify anastomosis patency, we utilize sodium fluorescein and iodine contrast. RESULTS: The 2-stage model simulated several aspects of microvascular anastomosis. Our perfusion system allowed for intraoperative adjustments of hydrodynamic pressure and pulsation. Using iodine contrast and fluorescein enabled proper evaluation of anastomosis patency and hydrodynamic features. CONCLUSIONS: Training in the laboratory is essential for developing microsurgical skills. We have presented a model for microvascular anastomosis with artificial circulation and postoperative imaging evaluation, which is highly beneficial for enhancing the learning curve in microvascular procedures.

Superficial Temporal Artery-Middle Cerebral Artery Bypass Ex Vivo Hybrid Simulator: Face, Content, Construct, and Concurrent Validity.

BACKGROUND: Cerebrovascular bypass surgical procedures require highly developed dexterity and refined bimanual technical skills. To attain such a level of prowess, neurosurgeons and residents have traditionally relied on "flat" models (without depth of field), such as chicken wings, live rats, silicone vessels, and other materials that stray far from the reality of the operating room, albeit more accessible. We have explored the use of a hybrid ex vivo simulator that takes advantage of the availability of placenta vessels and retains the complexity of surgery performed on a human skull to create a more realistic method for the development of cerebrovascular bypass surgical skills. METHODS: Twelve ex vivo simulators were constructed using 3 human placentas and 1 synthetic human skull for each. Face, content, construct, and concurrent validity were assessed by 12 neurosurgeons (6 trained vascular surgeons and 6 general neurosurgeons) and compared with those of other bypass models. RESULTS: The fidelity grade was ranked as low (Linkert scale score, 1-2), medium (score, 3), and high (score, 4-5). The face and content validity of the model showed high fidelity to superficial temporal artery-middle cerebral artery bypass surgery. Construct validity showed that cerebrovascular neurosurgeons had better performance, and concurrent validity highlighted that all surgical steps were present. CONCLUSION: The simulator was found to have strong face and content, construct, and concurrent validity for microsurgical cerebrovascular training, allowing for simulation of all surgical steps of the bypass procedure. The hybrid simulator seems to be a promising method for shortening the bypass surgery learning curve. However, more studies are required to evaluate the predictive validity of the model.

The Anterolateral Limit of the Occipital Lobe: An Anatomical and Imaging Study.

Objectives The boundaries of the temporal lobe, the parietal lobe, and the anterior portion of the occipital lobe (OL) are poorly defined. Lesions in these areas can be difficult to localize. Therefore, we studied the anterolateral limit of the OL to identify reliable anatomical landmarks. Design In 10 formalin-fixed cadaveric heads, the boundaries of the OL and relative anatomical landmarks were studied. Main Outcome Measures Distances between the following structures were measured: (1) preoccipital tentorial plica (POTP) to the junction between lambdoid suture and superior border of the transverse sinus (POTP-SL), (2) POTP to the sinodural angle of Citelli (POTP-PP), (3) lambda to parietooccipital sulcus (L-POS), and (4) preoccipital notch to termination of the vein of Labbé (PON-VL). Landmarks in 559 computed tomography and magnetic resonance images were also studied. Results The POTP was found on the tentorium of all anatomical specimens, located at the same coronal level as the PON and its attachment to the bony protuberance (BP) at the lateral cranial wall. The mean distances were POTP-SL, 6.5 ± 6.4 mm; POTP-PP, 18.1 ± 7.8 mm; L-POS, 10.8 ± 5.0 mm; and PON-VL, 8.8 ± 10.1 mm. Conclusion Osseous (asterion, lambda, and BP), dural (POTP), and vascular (VL) landmarks can be used as reference structures to identify the anterolateral limit of the OL.

Intracerebral hemorrhage due to cerebral amyloid angiopathy after head injury: Report of a case and review of the literature.

Cerebral amyloid angiopathy (CAA) is an important cause of spontaneous intracerebral hemorrhage in the elderly. A few case reports of CAA-related intracerebral hemorrhage after head injury, usually following a fall, have been published. More rarely, it may occur in the setting of a traffic accident, with only four cases having been reported. We describe a case of CAA-related intracerebral hemorrhage in an 88-year-old man injured in a road traffic accident. The patient died 14 h after the accident. Autopsy examination revealed a left frontoparietal hematoma and CAA of most of the small leptomeningeal and cortical arteries, as well as several capillaries, predominantly in the parietal and occipital lobes. Except for bruises in the frontal and zygomatic regions, elbow and forearm, to the left, there were no skull fractures or traumatic lesions in other parts of the body. We review the literature on CAA-related intracerebral hemorrhage associated with head injury. CAA-related intracerebral hemorrhage after head injury may occur due to a minor trauma, minor and severe falls, or in the setting of a traffic accident. However, even in this last condition, it seems to happen mostly in patients who had a mild to moderate head injury. These facts show that replacement of the contractile components of the arterial tunica media by amyloid renders the affected cerebral blood vessels more vulnerable to head injury associated with acceleration and deceleration, independently of the severity of the dynamic loading acting on the head.

Midline as a landmark for the position of the superior sagittal sinus on the cranial vault: An anatomical and imaging study.

BACKGROUND: Craniotomies involving the midline are regular practice in neurosurgery, during which injury to the superior sagittal sinus (SSS), an uncommon yet devastating event, may occur. The midline tends to be the most common landmark used to identify the position of the SSS. In this study we examined the reliability of the midline as a landmark for the SSS. METHODS: We performed bilateral craniectomies on eight cadaveric heads, preserving the coronal, sagittal, and lambdoid sutures. The width of the SSS and its displacement from midline were measured on the cadaveric specimens and on 105 normal magnetic resonance images (MRIs) of the head at the following locations: halfway between nasion and bregma (NB), bregma (B), halfway between bregma and lambda (BL), lambda (L), and inion (I). RESULTS: In all cadaveric specimens, the SSS was partially or totally displaced toward one side of midline, usually to the right. It tended to be closer to midline in the frontal region and more displaced posteriorly. The SSS usually drained into the right-side transverse sinus. The mean width of the SSS was 4.3, 5.9, 6.9, 7.9, and 7.8 mm, and the average displacement from midline was 4.3, 6.3, 5.5, 6.9, and 6.0 mm for NB, B, BL, L, and I, respectively. These measurements were then compared with those obtained from the MRIs. CONCLUSION: The SSS was consistently displaced on either side of midline. Thus, the midline is not reliable for identifying the SSS, and caution should be used within 6-10 mm on either side of midline.

The history of neurosurgical procedures for moyamoya disease.

Almost 50 years of research on moyamoya disease (1957-2006) has led to the development of a variety of surgical and medical options for its management in affected patients. Some of these options have been abandoned, others have served as the basis for the development of better procedures, and many are still in use today. Investigators studying moyamoya disease during this period have concluded that the best treatment is planned after studying each patient's presenting symptoms and angiographic pattern. The surgical procedures proposed for the treatment of moyamoya disease can be classified into three categories: direct arterial bypasses, indirect arterial bypasses, and other methods. Direct bypass methods that have been proposed are vein grafts and extracranial-intracranial anastomosis (superficial temporal artery-middle cerebral artery [STA-MCA] anastomosis and occipital artery-MCA anastomosis). Indirect techniques that have been proposed are the following: 1) encephaloduroarteriosynangiosis; 2) encephalomyosynangiosis; 3) encephalomyoarteriosynangiosis; 4) multiple cranial bur holes; and 5) transplantation of omentum. Other options such as cervical carotid sympathectomy and superior cervical ganglionectomy have also been proposed. In this paper the authors describe the history of the development of surgical techniques for treating moyamoya disease.

[Decompressive craniotomy for the early treatment of traumatic intracranial hypertension]. / Craniotomia descompressiva para tratamento precoce da hipertensão intracraniana traumática.

There is no clear role for decompressive craniotomy (DC) for the intracranial hypertension (ICH) treatment in the literature. Actually, there is a lack of class I or II published data for DC, so it is recomended as a second tier option for the refractory ICH. Recent studies has analized the role of early DC for pos traumatic ICH. The present study analizes 21 patients who has received the early DC for the treatment of traumatic ICH. The majority of the patients had Glasgow Coma Scale < 9 and harboring a brain swelling or acute subdural hematoma at cranial computadorized tomography. Hydrocephalus was frequent after DC (28.5%). Good results were obtained in 11 patients (52.5%). We favour the early application of DC for pos traumatic hypertension.

Craniotomia descompressiva para tratamento precoce da hipertensão intracraniana traumática / Decompressive craniotomy for the early treatment of traumatic intracranial hypertension

O papel da craniotomia descompressiva (CD) no tratamento da hipertensão intracraniana (HIC) refratária ainda não está estabelecido na literatura. Atualmente é recomendada como opção, pois há deficiência de trabalhos classe I ou II que suportem seu emprego. Trabalhos recentes têm avaliado a eficácia da CD quando aplicada precocemente no tratamento da HIC pós traumática. No presente trabalho analisam-se 21 pacientes nos quais a CD foi realizada precocemente. A maioria dos pacientes apresentava traumatismo cranioencefálico grave (Escala de coma glasgow <9) e tomografia de crânio evidenciando tumefação cerebral (brain swelling) ou hematoma subdural agudo. A principal complicação inerente à técnica foi a hidrocefalia (28,5 por cento). Boa reabilitação social ocorreu em 11 pacientes (52,5 por cento). Parece que a CD, quando realizada precocemente, é eficaz no tratamento da HIC refratária, ressaltando-se ainda a necessidade de estudos classe I e II que suportem esta opinião.

Diffuse vascular injury in fatal road traffic accident victims: its relationship to diffuse axonal injury.

The authors have reported a macro- and microscopic study of brain lesions in 120 victims of fatal road traffic accidents, independent of the survival time. Diffuse vascular injury (DVI) was found in 14 patients (11.7%). All patients with DVI died within 24 h after the accident. The 14 patients with DVI also showed severe (Grade 2 or 3) diffuse axonal injury (DAI). Since DVI is restricted to road traffic accidents and incompatible with life, the high frequency observed in our series could be explained by the fact that all 120 patients were victims of road traffic accidents, and 69.2% had died within 24 h after the accident. The association between DVI and severe DAI (Grades 2 and 3) suggests that both lesions depend on the same mechanism, with the degree of axonal and vascular damage being determined by the intensity of the head acceleration. Our results show a relationship between DVI and DAI that suggest there may be a spectrum or at least a continuum between these entities as distinct from DVI being a separate entity.

Lesäo axonal difusa: aspectos fisiopatológicos / Diffuse axonal injury: physiopathological aspects

É realizada uma revisäo da literatura sobre a lesäo axonal difusa, enfocando especialmente a sua biomecâmica. Com base nos trabalhos da literatura e dos autores é proposta uma explicaçäo mecânica, baseada na açäo das forças inerciais sobre a conformaçäo característica do encéfalo, para a localizaçäo mais freqüente e lateralizada da lesäo axonal difusa nas formaçöes inter-hemisféricas e na porçäo rostral do tronco encefálico.