Critical reviews in neurosurgery : CR最新文献

In this manuscript, the authors review current developments in intraoperative magnetic resonance imaging (MRI) and analyze the feasibility of obtaining intraoperative MRI images, current available instrumentation, and the advantages and disadvantages of performing a neurosurgical procedure using interactive or real time scans and neuronavigation.

Solitary fibrous tumors most often affect the pleura, but examples are increasingly being reported in a wide variety of sites including the central nervous system. This tumor shows characteristic expression of CD34, which facilitates histopathologic differentiation of this lesion from other more common and better recognized spindle-cell tumors such as fibrous meningioma, hemangiopericytoma, or nerve sheath tumors. In this paper, we review current information on cranial and paracranial solitary fibrous tumors and emphasize the need for clinical recognition of this lesion as a distinct entity.

While oxyhemoglobin (oxyHb) is deemed to be the principal cause of cerebral vasospasm following subarachnoid hemorrhage, the mechanism(s) whereby it leads to vasospasm is by no means clear. Of importance is the fact that prolonged contraction of arterial smooth muscle is not the sole feature of cerebral vasospasm, particularly in humans. Vasospasm is also associated with the occurrence of organic changes in the arterial wall as well as the derangement of cerebral microcirculation. These additional features may play a pivotal role when vasospasm in the proximal arteries incurs delayed ischemic neurological deficits and cerebral infarction. The question then arises as to whether or not all the features of vasospasm are attributable to the actions of oxyHb. In this regard, owing to the recent advances in vascular physiology, it has become clear that the cerebral vasculature should be regarded as an organ, not a mere conduit, in which all intracellular mechanisms are functionally integrated for the maintenance and regulation of cerebral blood flow (CBF). In the sense that the arterial function is not simply a sum of the individual cellular functions, it may be described as "holistic". According to extant literature, oxyHb has multifarious actions that can be divided into the following three categories: (1) scavenging of nitric oxide (NO), (2) generation of reactive oxygen species (ROS), (3) activation of the tyrosine kinase/mitogen-activated kinase (TK/MAPK) pathway. Based on such knowledge, the present review aims at a speculative synthesis in terms of how oxyHb pertains to the occurrence of vasospasm, in which the highly integrated, holistic mechanisms within the cerebral artery are perturbed for a prolonged period.

The pathophysiology behind "the syndrome of the trephined" has been under investigation over the past 50 years. Research related to barometric pressure, cellular metabolism, cerebrospinal fluid (CSF) dynamics, and the vasculature have attempted to decipher the mechanism of disease. These subjects are discussed in five papers along with specific topics related to the syndrome. The symptoms experienced after craniectomy, the resolution of symptoms with cranioplasty as well as CSF, cerebral blood flow, and metabolic studies are presented, respectively, with a review of the theories.

The morphological variability, diameter, and length of the anterior communicating artery (ACoA) are important factors in clinical and surgical decisions. This artery presents branches that supply the optic nerves and chiasm, the lamina terminalis, the hypothalamus, and the subcallosal region. The ACoA has the most frequent incidence of saccular aneurysms in the anterior portion of the circle of Willis. Lesions to the ACoA's branches may be related to neuropsychological sequelae such as amnesia, confabulation and personality changes, besides other basal ganglia syndromes. In this paper, anatomical studies of the ACoA and its branches are reviewed and the results of an anatomical study carried out in our laboratory presented.

This article reviews recent reports on high-dose chemotherapy combined with autologous stem-cell rescue for patients with newly diagnosed or recurrent malignant brain tumors. Children with newly diagnosed malignant central nervous system (CNS) tumors are included - in these patients it was desirable to avoid radiotherapy. The drugs used were thiotepa, etoposide, cyclophosphamide, busulfan, melphalan, and carboplatin. At a toxic death rate of 8-13%, their toxicity was considered acceptable. However, in patients receiving high-dose chemotherapy, neurologic complications were not uncommon. Therefore, the effects of this drug therapy on the post-treatment cognitive function of long-term survivors must be examined prospectively. Regarding the types of tumor that respond to drug therapy, medulloblastoma and cerebral primitive neuroectodermal tumor (PNET) appear to be good candidates, as are malignant astrocytic tumors in the cerebral hemisphere of children younger than 3 years. On the other hand, brain stem gliomas do not appear to respond well to high-dose chemotherapy. Radiotherapy can be avoided in a significant proportion of young children with malignant brain tumors. Larger patient series need to be studied to determine which patients are most likely to benefit from high-dose chemotherapy and to pinpoint the optimal time for treatment intervention.

Since the introduction of anterior approaches to the cervical spine for the surgical treatment of degenerative disc disease, controversies have developed regarding the necessity of fusion following anterior cervical discectomy, the use of allografts instead of autologous bone for fusion, and, recently, the employment of anterior cervical plating systems in addition to fusion for uncomplicated disc disease. We reviewed seven clinical papers dealing with these issues; these articles surveyed a total of 1153 patients. Several observations can be made from these reviews. First, there is little or no difference in clinical outcome following single-level anterior discectomy, whether a fusion is performed or not, regardless of whether the operation was for soft discs or osteophytes. Second, most patients who underwent two-level discectomies had outcomes comparable to patients who underwent surgery at one level, regardless of whether they were fused or not. Data from four prospective randomized clinical studies in addition to multiple non-randomized or retrospective studies support these conclusions. Although the incidence of complications such as persistent postoperative posterior cervical and shoulder pain and kyphotic deformities is higher in unfused patients (and is quite significant in some series), the advantages conferred by interbody fusion such as biomechanical stability, decreased incidence of kyphotic deformity, and decreased pain are offset by graft and donor-site morbidity. Specific indications for fusion include multi-level discectomies, significant straightening of the cervical spine, failed prior fusions, and trauma. It has been demonstrated that comparable fusion rates can be achieved with allografts rather than harvested autologous bone. The advantages of autografts over allografts are relatively slight in most patients who undergo anterior fusion for one- or two-level disc disease, although patients with impaired healing, significant osteopenia, or concomitant microvascular disease, such as chronic smokers, may benefit from autologous bone. The use of allografts avoids donor-site morbidity in patients without these problems. Anterior cervical plates are useful for cases of instability requiring fusion (such as trauma); these implants may decrease reoperation rates and the incidence of delayed instability in select cases. However, the cost-effectiveness of their generalized use for uncomplicated cervical disc disease has not been demonstrated. In conclusion, a general statement regarding the optimal surgical treatment for cervical disc herniations using anterior approaches is difficult to make with this limited review. Surgeons' experience and familiarity with a particular approach are probably the most important factors in ensuring successful outcomes.