Eberval Gadelha Figueiredo

Decompressive craniectomy: a meta-analysis of influences on intracranial pressure and cerebral perfusion pressure in the treatment of traumatic brain injury

OBJECT In recent years, the role of decompressive craniectomy for the treatment of traumatic brain injury (TBI) in patients with refractory intracranial hypertension has been the subject of several studies. The purpose of this review was to evaluate the contribution of decompressive craniectomy in reducing intracranial pressure (ICP) and increasing cerebral perfusion pressure (CPP) in these patients. METHODS Comprehensive literature searches were performed for articles related to the effects of decompressive craniectomy on ICP and CPP in patients with TBI. Inclusion criteria were as follows: 1) published manuscripts, 2) original articles of any study design except case reports, 3) patients with refractory elevated ICP due to traumatic brain swelling, 4) decompressive craniectomy as a type of intervention, and 5) availability of pre- and postoperative ICP and/or CPP data. Primary outcomes were ICP decrease and/or CPP increase for assessing the efficacy of decompressive craniectomy. The secondary outcome was the persistence of reduced ICP 24 and 48 hours after the operation. RESULTS Postoperative ICP values were significantly lower than preoperative values immediately after decompressive craniectomy (weighted mean difference [WMD] -17.59 mm Hg, 95% CI -23.45 to -11.73, p < 0.00001), 24 hours after (WMD -14.27 mm Hg, 95% CI -24.13 to -4.41, p < 0.00001), and 48 hours after (WMD -12.69 mm Hg, 95% CI -22.99 to -2.39, p < 0.0001). Postoperative CPP was significantly higher than preoperative values (WMD 7.37 mm Hg, 95% CI 2.32 to 12.42, p < 0.0001). CONCLUSIONS Decompressive craniectomy can effectively decrease ICP and increase CPP in patients with TBI and refractory elevated ICP. Further studies are necessary to define the group of patients that can benefit most from this procedure.

Microsurgical anatomy of the safe entry zones on the anterolateral brainstem related to surgical approaches to cavernous malformations.

OBJECTIVE To study the microanatomy of the brainstem related to the different safe entry zones used to approach intrinsic brainstem lesions. METHODS Ten formalin-fixed and frozen brainstem specimens (20 sides) were analyzed. The white fiber dissection technique was used to study the intrinsic microsurgical anatomy as related to safe entry zones on the brainstem surface. Three anatomic landmarks on the anterolateral brainstem surface were selected: lateral mesencephalic sulcus, peritrigeminal area, and olivary body. Ten other specimens were used to study the axial sections of the inferior olivary nucleus. The clinical application of these anatomic nuances is presented. RESULTS The lateral mesencephalic sulcus has a length of 7.4 to 13.3 mm (mean, 9.6 mm) and can be dissected safely in depths up to 4.9 to 11.7 mm (mean, 8.02 mm). In the peritrigeminal area, the distance of the fifth cranial nerve to the pyramidal tract is 3.1 to 5.7 mm (mean, 4.64 mm). The dissection may be performed 9.5 to 13.1 mm (mean, 11.2 mm) deeper, to the nucleus of the fifth cranial nerve. The inferior olivary nucleus provides safe access to lesions located up to 4.7 to 6.9 mm (mean, 5.52 mm) in the anterolateral aspect of the medulla. Clinical results confirm that these entry zones constitute surgical routes through which the brainstem may be safely approached. CONCLUSION The white fiber dissection technique is a valuable tool for understanding the three-dimensional disposition of the anatomic structures. The lateral mesencephalic sulcus, the peritrigeminal area, and the inferior olivary nucleus provide surgical spaces and delineate the relatively safe alleys where the brainstem can be approached without injuring important neural structures.

The minipterional craniotomy: technical description and anatomic assessment.

OBJECTIVE To describe a modification of the pterional approach (PT), the minipterional craniotomy (MPT), and compare the anatomic exposure provided by these two approaches. METHODS The anatomic exposure offered by the MPT and PT were compared in eight sides of cadaver heads using a computerized tracking system, a robotic microscope, and an image-guidance system. The area of surgical exposure, angular exposure, and anatomic limits of each craniotomy were evaluated. Three recently operated clinical cases (EGF) are also reported. RESULTS There were no statistical differences in the total area of surgical exposure between the two craniotomies (PT, 1524.7 ± 305 mm2; MPT, 1469.7 ± 380.3 mm2; P > 0.05) or among the ipsilateral, middle, and contralateral components of the area (P > 0.05). There were no differences in angular exposure along the longitudinal and transverse axis angles for the three selected targets, the bifurcations of internal carotid and middle cerebral arteries, and the anterior communicating artery (P > 0.05). Except for the distal portion of the operculoinsular compartment of the sylvian fissure, no significant differences in the limits of the surgical exposure through the PT and MPT were apparent on the image-guidance system. CONCLUSION The MPT craniotomy provides comparable surgical exposure to that offered by the PT. The advantages of the MPT include reduction of tissue trauma and bony removal, a decrease in surgical time, and improved cosmetic outcomes.

Quantitative anatomic study of three surgical approaches to the anterior communicating artery complex.

OBJECTIVE: To compare the angles of approach and area of exposure to the anterior communicating artery (AComA) complex associated with pterional (PT), orbitopterional (OPT), and orbitozygomatic (OZ) craniotomies before and after gyrus rectus resection. METHODS: PT, OPT, and OZ craniotomies were performed on both sides of four heads, and the angles of approach and area of exposure to the AComA complex were measured before and after resection of the gyrus rectus. RESULTS: The vertical angle of approach increased significantly among the PT and OPT (P = 0.001), PT and OZ (P = 0.001), and OPT and OZ approaches (P = 0.005). The horizontal angle of approach was significantly larger between the PT to OPT (P = 0.001) and PT to OZ (P = 0.001) approaches but not between the OPT and OZ approaches (P = 0.757). After gyrus rectus resection, the vertical and horizontal angles of approach increased significantly for the PT approach but not for the OPT and OZ approaches. The area of exposure to the AComA complex increased progressively from the PT to OPT to OZ approach but did not reach statistical significance (P = 0.124). Resection of the gyrus rectus resulted in significant relative gains in the area of exposure for the PT (P = 0.01) and OPT (P = 0.04) approaches but not for the OZ approach (P = 0.88). CONCLUSION: The vertical and horizontal angles of approach to the AComA complex are significantly larger for the OPT and OZ approaches compared with the PT approach. Use of the OZ approach may decrease the need for frontal lobe retraction and resection of the gyrus rectus.

Cerebral hemodynamics: concepts of clinical importance

Cerebral hemodynamics and metabolism are frequently impaired in a wide range of neurological diseases, including traumatic brain injury and stroke, with several pathophysiological mechanisms of injury. The resultant uncoupling of cerebral blood flow and metabolism can trigger secondary brain lesions, particularly in early phases, consequently worsening the patients outcome. Cerebral blood flow regulation is influenced by blood gas content, blood viscosity, body temperature, cardiac output, altitude, cerebrovascular autoregulation, and neurovascular coupling, mediated by chemical agents such as nitric oxide (NO), carbon monoxide (CO), eicosanoid products, oxygen-derived free radicals, endothelins, K+, H+, and adenosine. A better understanding of these factors is valuable for the management of neurocritical care patients. The assessment of both cerebral hemodynamics and metabolism in the acute phase of neurocritical care conditions may contribute to a more effective planning of therapeutic strategies for reducing secondary brain lesions. In this review, the authors have discussed concepts of cerebral hemodynamics, considering aspects of clinical importance.

MR AND CT IMAGING IN THE DYKE-DAVIDOFF-MASSON SYNDROME : REPORT OF THREE CASES AND CONTRIBUTION TO PATHOGENESIS AND DIFFERENTIAL DIAGNOSIS

Cerebral hemiatrophy or Dyke-Davidoff-Masson syndrome is a condition characterized by seizures, facial asymmetry, contralateral hemiplegia or hemiparesis, and mental retardation. These findings are due to cerebral injury that may occur early in life or in utero. The radiological features are unilateral loss of cerebral volume and associated compensatory bone alterations in the calvarium, like thickening, hyperpneumatization of the paranasal sinuses and mastoid cells and elevation of the petrous ridge. The authors describe three cases. Classical findings of the syndrome are present in variable degrees according to the extent of the brain injury. Pathogenesis is commented.

Decompressive craniectomy and head injury: brain morphometry, ICP, cerebral hemodynamics, cerebral microvascular reactivity, and neurochemistry

There has been renewed interest in decompressive craniectomy as a surgical treatment for elevated intracranial pressure (ICP), although evidence-based clinical data are still lacking and some experimental results are conflicting. Ongoing clinical trials on the use of this operation after traumatic brain injury (TBI) may clarify the clinical application of this technique, however, some pathophysiological issues, such as the timing of this operation, its effect on brain edema formation, and its role for secondary brain damage, are still controversial. This review addresses recent clinical data on the influence of decompressive craniectomy on the brain pathophysiology in TBI. Decompressive craniectomy with dural augmentation enlarges intracranial space so that the swollen cerebral hemisphere could expand out of normal cranial limits, avoiding progression of brain herniation. The gain in intracranial volume results in both the improvement of cerebral compliance and a decrease in ICP; the latter favors a rise in both cerebral blood flow and cerebral microvascular perfusion, which can be accompanied by elevation in brain tissue oxygen tension (PbtO2) as well as the return of abnormal metabolic parameters to normal values in cases of cerebral ischemia. Enhancement of edema formation, impairment of cerebrovascular pressure reactivity, and non-restoration of brain aerobic metabolism due to metabolic crisis may occur after craniectomy and require further investigations. This review suggests that decompressive craniectomy as the sole treatment is likely to be insufficient; efforts must be made to maintain adequate brain hemodynamics, preferably coupled with brain metabolism, in addition to treating brain metabolic abnormalities, during postoperative stages.

Leptomeningeal dissemination of pilocytic astrocytoma at diagnosis in childhood: two cases report

Pilocytic astrocytoma (PA) is a benign tumor that rarely spread along the neuraxis. At the moment there are no more than five cases of leptomeningeal dissemination (LD) from PA at diagnosis described in the literature. Different patterns of presentation or recurrence may be noted: local recurrence, malignant transformation, multicentric disease or metastatic disease. LD and multicentric disease can be distinct pathological entities. We report two cases and analyse literature, emphasizing leptomeningeal spread at presentation. Hydrocephalus, biopsy and parcial ressection are likely to be favorable factors to the occurrence of LD. Otherwise, LD may be part of natural history of PA, as evidenced by its ocurrence in non-treated cases.

Mecanismos de lesão cerebral no traumatismo cranioencefálico

Traumatic brain injury is the main cause of death and disability in children and adults in Western Countries. The definitive brain injury is a consequence of pathophysiological mechanisms that begin at the moment of an accident and may extend for days or weeks. Traumatic brain injury may be classified as diffuse or focal. These two mechanisms are commonly associated in a patient, however one is generally predominant. Therefore knowledge of the pathophysiological mechanisms of brain injury in head trauma is important to establish the therapeutic, clinical and surgical measures. In this paper the authors present a critical review of the literature on the pathophysiological principles of traumatic brain injury.

Guidelines for neurosurgical trauma in Brazil

This chapter emphasizes some aspects of the Brazilian Guidelines for the Assessment of Head Injury Patients, written based on the experience of the Emergency Service, Neurosurgical Division of the University of São Paulo Medical School Hospital, and sponsored by the Brazilian Society of Neurosurgery. These guidelines approach the management of head-injury patients from their initial assessment in the Emergency Room until the final suggested clinical or surgical management. The Brazilian Guidelines represents our efforts to provide the basis for a common unified data collection system, which may allow cooperative studies in the future.