Features and functions of decision support systems for appropriate diagnostic imaging: a scoping review.

BACKGROUND: Diagnostic imaging decision support (DI-DS) systems could be effective tools for reducing inappropriate diagnostic imaging examinations. Since effective design and evaluation of these systems requires in-depth understanding of their features and functions, the present study aims to map the existing literature on DI-DS systems to identify features and functions of these systems. METHODS: The search was performed using Scopus, Embase, PubMed, Web of Science, and Cochrane Central Registry of Controlled Trials (CENTRAL) and was limited to 2000 to 2021. Analytical studies, descriptive studies, reviews and book chapters that explicitly addressed the functions or features of DI-DS systems were included. RESULTS: A total of 6,046 studies were identified. Out of these, 55 studies met the inclusion criteria. From these, 22 functions and 22 features were identified. Some of the identified features were: visibility, content chunking/grouping, deployed as a multidisciplinary program, clinically valid and relevant feedback, embedding current evidence, and targeted recommendations. And, some of the identified functions were: displaying an appropriateness score, recommending alternative or more appropriate imaging examination(s), providing recommendations for next diagnostic steps, and providing safety alerts. CONCLUSIONS: The set of features and functions obtained in the present study can provide a basis for developing well-designed DI-DS systems, which could help to improve adherence to diagnostic imaging guidelines, minimize unnecessary costs, and improve the outcome of care through appropriate diagnosis and on-time care delivery.

Psychological consideration in patients with cerebral gliomas candidates for intra-operative radiation therapy based on tumor location.

OBJECTIVE: Intra-operative Radiation Therapy (IORT) is gaining popularity as an adjuvant option to surgical resection, in treatment of glioblastoma multiforme (GBM) for increasing survival rate, which a highly aggressive cerebral tumor with poor prognosis. Τhe authors plan to investigate the effects of IORT combined with surgical resection on the psychological status of these patients based on tumor location. SUBJECT AND METHODS: From December 2013 to February 2017, we have enrolled 109 patients with high grade cerebral gliomas, documented by Magnetic Resonance Spectroscopy (MRS). Patients with previous history of brain surgery or radiation, altered mental status and psychological content and patients diagnosed with metastases were excluded. Demographic data, tumor volume based on pre-operative Magnetic Resonance Imaging (MRI) and psychological status were recorded based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria. The remaining 56 patients, were equally randomized into conventional (surgical resection-group A), and trial (surgical resection with IORT-group B) who underwent IORT using the 50kV INTRABEAM® system (Carl Zeiss Meditec AG, Germany). Psychological profiles of both groups were re-evaluated in the 3rd post-operative month. RESULTS: Group A consisted of 18 males and 10 females with mean age of 54.4 years, while group B consisted of 16 males and 12 females with mean age of 57.8 years. Tumor volumetry revealed mean 81.52cc and 82.8cc for group A and B respectively. (P value 0.14) Patients were classified based on glioma location on pre-operative MRI: a) left parietal lobe (6 in group A, 5 in group B); b) left temporal lobe (7 in group A, 5 in group B); c) right parietal lobe (5 in group A, 6 in group B); d) left fronto-temporal lobe (4 in group A, 6 in group B); e) left parieto-temporal lobe (4 in group A, 5 in group B); and, f) right frontal lobe (2 in group A, 1 in group B). Group B received mean 8.05 Gy radiation for mean 11.2 minutes. Post-operative psychological in the 3rd month evaluation revealed the following in each class: a) Group A: 1 mild depression, Group B: 1 mild depression and 2 major depression; b) Group A: no disorder, Group B: 1 mild depression; c) no disorders in both groups; d) Group A: no disorder, Group B: 1 mild depression, 1 major depression and 1 Obsessive-Compulsive Disorder (OCD); Conclusion: Utilization of IORT is shown to improve survival rate of patients suffering from GBM. However, the psychological status is a major determinating factor for the quality of life of these patients. Our study showed that IORT increased psychological disorders in patients with gliomas located in left parietal, left fronto-temporal and left parieto-temporal lobes and should be considered in pre-operative strategy selection.

Deep brain nucleus targeting in Parkinson's disease and essential tremor by image guided surgery using neuronavigation system with tractography and volume of tissue of activated assessment.

OBJECTIVE: Deep Brain Stimulation (DBS) is an effective surgical approach for treatment of Parkinson's disease (PD), dystonia and essential tremor (ET). Traditionally, DBS is performed using frame-based stereotactic technique. Recently, image guided surgery (IGS) using neuronavigation has gained popularity in neurosurgical procedures. We aim to investigate whether DBS using neuronavigation is capable of improving patient's outcome and minimize its complications. SUBJECT AND METHODS: From February 2011 to October 2016, 20 patients with PD and 6 patients with ET were enrolled in the study. Patients aged between 18 to 70 years, were included and they underwent Magnetic Resonance Imaging (MRI) for deep brain nucleus volumetry. Among PD patients, 14 cases underwent subthalamic nucleus (STN) implantation, while other 6 cases underwent globus pallidus internus (GPi) implantation. Furthermore, ventral intermediate nucleus (VIN) implantation was performed for ET patients, all with IGS using neuronavigation system. Patients were assessed by unified Parkinson's disease rating scale (UPDRS) for PD and tremor scores for ET in their follow ups. Authors utilized Butson model for volume of tissue activated (VTA) assessment. In addition, detailed tractography was performed to evaluate white matter circuits radiating from deep nucleuses. RESULTS: PD patients with GPi volume of more than 600mm3 and less than 400mm3 were excluded from the study. Mean right and left GPi volume was 519±94.2mm3 and 480±80.3mm3, respectively. Calculated VTA based on Butson model revealed that 70% of cases who exhibited improved UPDRS of more than 50% in the 7th month of follow-up, had their VTA outside their defined GPi and STN boundaries with outer layer overlap. In contrast, 60% of cases who showed UPDRS improvement of less than 50% in same follow-up month, have their VTA inside defined GPi and STN boundaries. Moreover, ET patients experienced mean 55% and 79% improvement in tremor scores at mean 6.7 and 9.9 follow up month respectively. No surgery related complications were observed. Furthermore, tractography analysis revealed increased superior frontal gyrus and thalamus connection in patients with improved UPDRS. CONCLUSION: IGS using neuronavigation allowed more accurate deep nucleus targeting, minimized intra- and post-operative complications and improved clinical outcome in DBS candidate patients. Our study revealed that increased white matter connections with remote parts of the brain would suggest that isolated deep nucleus stimulation could not explain symptom recovery and that patients' specific white matter stimulation by tractography coupled with IGS should be in priority.

Treatment Results for Pineal Region Tumors: Role of Stereotactic Biopsy Plus Adjuvant Therapy vs. Open Resection.

AIM: Pineal tumors represent uncommon intracranial tumors with highly diverse histologic subtypes. There still exists a controversy in literature about what influences overall survival and outcome. MATERIAL AND METHODS: We present the results of 48 patients with pineal tumor treated either by stereotactic biopsy followed by adjuvant therapy (23 patients) or open surgical resection without (18 patients) or with (7 patients) adjuvant therapy in Shohada Tajrish Hospital, Iran (1993-2008). RESULTS: Unremarkable pathology yield was 3/23 in the biopsy and 1/25 in the surgical group. Perioperative mortality and morbidity were 4.3% and 0% in the biopsy group and 32.0% and 4.0% in the surgical group. Analysis showed that age, gender, cranial nerve deficit, motor deficit, preoperative Karnofsky Performance Score (KPS), midbrain involvement, and brain stem involvement had no effect on neither perioperative mortality nor long-term survival, while local invasion and pineocytoma pathology increased perioperative mortality and presence of hydrocephalus and pineoblastoma pathology significantly decreased long-term survival. Hospitalization length was shorter in the stereotactic biopsy plus adjuvant therapy group. CONCLUSION: The results of the study suggests that although gross total resection is the standard of care in most pineal tumors nowadays, stereotactic biopsy followed by adjuvant therapy may still be a safe and viable option.

Psychological aspects in brain tumor patients: A prospective study.

OBJECTIVE: Very few studies have utilized specific criteria to assess mental disorders in brain tumor patients, and from them, they are mainly descriptive. The purpose of this study is to examine mental disorders in relation to tumor characteristics and patients' psychosocial factors using DSM-IV (depression, sleep and mood) criteria, among brain tumor patients. MATERIALS AND METHODS: From March 2009 to July 2011, 98 patients who surgically treated with intracranial neoplasm were included in this prospective study. The mean age of the patient group was 42.2 years with a range of 18-60 years with a male to female ratio of 1.2. The most common tumor type was glioblastoma multiform (30.3%), followed by meningioma (16.8%) and anaplastic glioma (12.3%). RESULTS: In our study, the prevalence of mild depression was about 30% for males and 38% for females before surgery; however at 3 months after surgery, this amount decreased to the amount of 25.6% and 26% for male and female patients respectively. Before tumor operation, the prevalence of major depression was 10.4% for males and 19.7% for females. At 3 months after operation the prevalence of major depression was 12.8% for males, and 6.7% for females. Aggression or suicide attempts were not seen related to depression. Before operative intervention, severe anxiousness as well as severe Obsessive Compulsive Disorder (OCD) symptoms was present in 14.7% of males while at 3 months after operation, prevalence of severe anxiousness and severe OCD symptoms decreased to 4% and 9.3% respectively. In females, 28.7% of the subjects had reported to have severe anxiousness and 25.6% severe OCD symptoms. Three months after surgery, these amounts were 17.6% and 38.7% respectively. CONCLUSION: Depressive symptoms as well as anxious and OCD psychopathology were shown to be prevalent signs among patients with brain tumor. Diagnosis of the previous mentioned symptoms were totally based on DSM-IV criteria and these disorders and the percentiles don't seem to be related to each other. Due to high variability of tumor stages, statistical analysis of whether the mentioned psychiatric symptoms get worsen at the later stages of the tumor genesis was not feasible. Although not measured directly, mentioned psychiatric symptoms seem to get worsen at the later stages of the brain tumor. The associated factors are tumor location, patient's premorbid psychiatric status, cognitive symptoms and adaptive or maladaptive response to stress.

Radioguided surgery using gamma detection probe technology for resection of cerebral glioma.

OBJECTIVE: Using microsurgical procedures without intraoperative imaging, Gross Total Resection (GTR) has so far only been achieved in less than 30% of all cases. Radio-guided surgery was introduced in the clinical setting in 1985 in an attempt to facilitate intraoperative tumor detection. Because of few studies in literature about this subject, we decided to use gamma probe with the hypothesis that we could increase extent of tumor resection. MATERIALS AND METHODS: From January 2013 till February 2014, 22 patients with cerebral glioma were randomized equally into two groups and evaluated. In the first group, 370MBq of Technetiumc-99m was injected. The microsurgical resection of the tumor was performed as much as possible, and then the tumoral bed was examined, if the signal was more than 2 times of the background signal, more tissue resection performed if feasible until the signal was diminished. In the control group, conventional resection of the tumor was performed. The extent of tumor resection was assessed by contrast magnetic resonance imaging (MRI) study. RESULTS: Before surgery the patients in the first group had average tumor volume of 81.68±9.78. In the second group the average tumor volume before surgery was 82.63±10.06cc. There is no significant difference between preoperative tumor volumes in two groups. In the first group, in the post-operative MRI, the tumor volume was 5.04±2.69cc and in the second group it was 9.5±4.8cc. Eight patients (72.7%) in the radioguided group experienced radical resection (more than 95%), but in the control group radical resection was achieved in just 3 patients (27.2%), radical resection was significantly higher in radioguided group (P<0.001). Due to the usage of the gamma detection probe, time of finding the tumor in the radioguided group was significantly less than control group (P=0.02). However total operation time in the radioguided group, was not significantly more than the control group (P=0.88). CONCLUSIONS: Neuronavigation system increases the percentage of gross total resection, but it is expensive, increases duration of surgery is not considered a real-time assessment, and is not accurate in determining the borders of glioma due to brain shift. In contrast, radio-guided surgery is easy to use, real time, not expensive, and increases the extent of tumor resection.

First Experience of Intraoperative Radiation Therapy in Cerebral High Grade Glioma in Iran: A Report of Three Cases and Literature Review.

INTRODUCTION: Among the high grade cerebral gliomas, Glioblastoma multiform for instance, would be the main pattern of local recurrence causes clinical deterioration and deaths. This has observed 2 - 3 cm upon the initial lesion. During the period of 2 - 4 weeks post-surgery, remaining tumor cells have re-grown until radiochemotherapy has initiated. So it has seemed clear that improved local control could hopefully translate into improved survival. As a matter of fact, mass reduction has insufficiently achieved in almost every case of GBM as that the tumor cell number has not fallen below a "threshold" that tumor control might achieve by the host immune system. Intraoperative Radiation therapy has been one of those add-on therapies, which has performed during or directly after resection and cleared the tumor cavity from microscopically remaining cells. Although IORT has presented a novel and feasible principle, the method faced a number of technical and geometrical errors and limitations, which has decreased its potential in the reports of previous studies. Examples could be mentioned as incomplete target volume coverage that seemed as the greatest influence on survival, due to irradiation with an inadequate electron cone size, due to angle errors, or inadequately low energies. In contrast to the previously used forward-beaming electron cones, spherical irradiation sources were specifically attractive in brain tumor IORT, even in post resection cavities with normal complex shapes. CASE PRESENTATION: We have been reporting 3 cases of high grade gliomas, one recurrent GBM, one primary glioma grade III, and the last one recurrent Rhabdoid GBM, which have been fulfilling our entrance criteria of IORT procedure, by using spherical applicators, which has been increasingly discussed in recent studies. CONCLUSIONS: It was the first experience of intraoperative radiation therapy for cerebral malignant tumours in Iran. Finally, we had a brief overview on the past and present IORT strategies in the treatment of GBM.

Evaluating the Possibility of Defining Cut-Off Points for ΔFA% in Order to Differentiate Four Major Types of Peri-Tumoral White Matter Tract Involvement.

BACKGROUND: Diffusion tensor imaging (DTI) and its different scalar values such as fractional anisotropy (FA) have recently been used for evaluation of peri-tumoral white matter (WM) involvement to help define safer surgical excision margins. OBJECTIVES: The purpose of this study is to evaluate the possibility of defining diagnostic cut-off points for differentiating four major types of peri-tumoral WM involvement using FA. PATIENTS AND METHODS: DTI was performed in 12 patients with high presumption of having brain tumors, on a 1.5 T MRI scanner. DTI data was processed by MedINRIA software. Two-hundred region of interests (ROI) were evaluated: 100 in the lesion zone and the rest in the normal WM in the contralateral hemisphere. FA value related to each ROI was measured, and the percentage of FA decrement (ΔFAs%) was calculated. RESULTS: Of the 100 ROIs on the lesion side, 74 were related to high-grade lesions, 23 to low-grade ones, and three to "gliosis". There were 54 "infiltrated", 22 "displaced", 15 "disrupted", and 9 "edematous" tracts. The major type of fiber involvement, both in low-grade and high-grade tumors was "infiltrated, whereas "edematous" fibers comprised the minority. ΔFA% was more than -35 for "displaced" and "edematous" fibers, and less than -35 for the majority of "disrupted" ones, but "infiltrated" fibers had scattered distribution. Mean ΔFA% was the least for "disrupted", followed by "infiltrated", "edematous" and "displaced" parts. CONCLUSION: Introducing definite diagnostic cut-points was not possible, due to overlap. Based on the fact that "disruption" is the most aggressive process, a sensitivity analysis was carried out for "disrupted" fibers for several presumptive cut-off points.

Effect of Ondansetron on Postoperative Shivering After Craniotomy.

INTRODUCTION: Postoperative shivering (POS) is an early complication after craniotomy. Preventive pharmacologic drugs are the mainstay of treatment. Meperidine is the drug of choice but with increased risk of apnea, nausea, and increased intracranial pressure. Some reports have suggested that ondansetron and meperidine have similar anti-shivering effects. OBJECTIVES: To assess the preventive effect of ondansetron on POS after craniotomy. METHODS: In a randomized, double-blind, placebo-controlled trial, 80 patients with American Society of Anesthesiologists status I to II between 20 and 60 years of age scheduled for elective craniotomy were enrolled in the study. Patients received either intravenous ondansetron 4 mg (n = 40) or saline (n = 40) 10 minutes before the end of surgery. RESULTS: POS was observed in 3 patients (7.5%) in the ondansetron group, significantly lower than in the control group (6 patients [15%]; P =0.048). Ondansetron decreased the relative risk of occurrence of POS after craniotomy from 4.42 (95% confidence interval [CI], 2.3-8.5; P = 0.0021) in the control group to 1.05 (95% CI, 0.76-2.20; P = 0.074). In the ondansetron group, the mean (± standard deviation) core temperature in the preoperative phase (36.6°C ± 0.66°C) was significantly higher than in the postoperative phase (34.2°C ± 0.56°C) (P = 0.001). In addition, the mean (± standard deviation) peripheral temperature in the preoperative phase (36.5°C ± 0.72°C) was significantly higher than in the postoperative phase (34.4°C ± 0.51°C) (P = 0.001). CONCLUSIONS: Ondansetron can effectively decrease POS after craniotomy. This effect is not mediated through maintenance of the core or peripheral temperature. Ondansetron probably acts by a central inhibitory mechanism on POS through 5-hydroxytryptaminergic pathways, not by changing thermoregulatory set points.

Clinical and magnetic resonance imaging factors which may predict the need for surgery in lumbar disc herniation.

STUDY DESIGN: Case-control. PURPOSE: Evaluate clinical and imaging factors which may predict the risk of failure of medical therapy in patients with lumbar disc herniation (LDH). OVERVIEW OF LITERATURE: LDH is a common cause of low back pain and radicular leg pain, with a generally favorable natural course. At present, however, it is not possible to identify patients who may be candidates for surgery in an early stage of their disease by means of clinical signs or diagnostic imaging criteria. METHODS: We designed a study investigating patients with untreated low back pain to assess the predictive value of demographic, clinical or imaging findings in identifying patients who finally would meet the classic current criteria for surgery. RESULTS: Among 134 patients, 80.6% were successfully treated with conservative therapy and 19.4% finally underwent surgery. Sex, occupation, involved root level, presence of Modic changes, osteophytes or annular tears were not significantly different between the 2 groups, while cerebrospinal fluid block, Pfirrmann's grade, location of herniation with regard to the midline, and type of herniation were significantly different. Anteroposterior fragment size was significantly higher and intervertebral foramen height and thecal sac diameters were significantly lower in the surgical group. CONCLUSIONS: Although it is strongly recommended to practice conservative management at first for patients with LDH symptoms, the results of this study shows that higher Pfirrmann's grade, more laterally located discs, extrusion and protrusion herniation types, and larger fragments could predict the risk of conservative treatment failure. This way, unnecessarily prolonged conservative management (beyond 4-8 weeks) may be precluded.

Factors predicting early deterioration in mild brain trauma: a prospective study.

PRIMARY OBJECTIVE: To evaluate risk factors for clinical deterioration in mild traumatic brain injury. RESEARCH DESIGN: Prospective cross-sectional. METHODS AND PROCEDURES: This study evaluated 203 patients with mild traumatic brain injury. A brain computed tomography scan was performed in all patients and they were observed for 6-48 hours. MAIN OUTCOMES AND RESULTS: Among these patients, 2.5% had cerebral contusions and the most common sites for contusions were frontal lobes; 94% of patients had no hematoma in the initial scan, while 3% had subgaleal haematoma, 1.5% had subdural haematoma, 1% showed subarachnoid haemorrhage, 0.5% intracerebral haemorrhage and 0.5% epidural haemorrhage. GCS was 15 in 96.6% and 13-14 in 3.4%. GCS deteriorated in three (1.5%). Presence of coagulopathy, anticoagulant drug use, GCS of 13-14 and increased age predicted further deterioration. Among CT findings, those with midline shift, cerebral contusion and diffuse cerebral oedema deteriorated more. Among different haematoma types, only SDH predicted a worse outcome. CONCLUSIONS: Although deterioration rarely occurs in patients with mild brain injury, those with coagulopathy, anticoagulant drug use, GCS of 13-14, increased age, midline shift, cerebral contusions, diffuse cerebral oedema and SDH were more prone to deterioration.

Comparison of the acute physiology and chronic health evaluation score (APACHE) II with GCS in predicting hospital mortality of neurosurgical intensive care unit patients.

BACKGROUND: The Glasgow Coma Scale (GCS) is popular, simple, and reliable, and provides information about the level of consciousness in trauma patients. However, a systemic evaluation scale specially in patients with multiple trauma is so important. The revised Acute Physiology and Chronic Health Evaluation system type 2 (APACHE II) is a physiologically based system including physiological variables. This study compares the efficacy of the predicting power for mortality and functional outcome of GCS and APACHEII in patients with multiple trauma in intensive care unit. METHODS: This study included the patients with head injury associated with systemic trauma admitted in the ICU of Shahid Rajaee Hospital in 2007 and 2008. Sensitivity, specificity and correct prediction of outcome by GCS and APACHE II were assessed and compared. RESULTS: This study included 93 patients (79 males, 14 females; mean age 60.5; range 14 to 87 years) with head injury associated with systemic trauma in 2007 and 2008. Mortality increased in the elderly group. The mean survival score using APACHE II was 36.5 and death score was 67.4 . These values using GCS were 10.3 and 6.8, respectively. CONCLUSION: For the assessment of mortality, the GCS score still provides simple, less-time consuming and effective information concerning head injury patients, especially in emergencies; however, for the prediction of mortality in patients with multiple trauma. APACHE II is superior to GCS since it includes the main physiologic parameters of patients.

Asymptomatic presentation of huge extradural hematoma in a patient with arachnoid cyst.

Haemorrhagic complications of arachnoid cysts have been reported as subdural or intracystic hematoma following trauma. In this paper, we report a patient with arachnoid cyst who developed extradural hematoma after a subtle head injury and presented with very mild symptoms in spite of the huge size of the hematoma.

Non-invasive estimation of cerebrospinal fluid pressure waveforms by means of retinal venous pulsatility and central aortic blood pressure.

Current techniques used for cerebrospinal fluid pressure (CSFp) measurements are invasive. They require a surgical procedure for placement of a pressure catheter in the brain ventricles or in the brain tissue. The human eye provides direct visualisation of its physiological structures and due to its anatomical connection with CSF via the retrolaminar optic nerve it may provide accessible information about CSFp. A total of 25 subjects were included in this study. 15 subjects were used to characterise the relationship between intraocular pressure (IOP), spontaneous retinal venous pulsatility (SRVP), and CSFp. IOP was manipulated and SRVP amplitudes recorded dynamically using the dynamic vessel analyzer (DVA). The relationship between IOP and SRVP amplitude was established to estimate CSFp. Additionally Doppler blood flow velocity of the middle cerebral artery and arterial blood pressure (ABP) were acquired for all subjects. This was to compare and validate our findings with an alternative approach (ICM+) which uses these values to estimate CSFp. A CSFp waveform was extracted from central blood pressure (CBP) waveform by removing its cardiac component frequency. Furthermore to calibrate the CSFp to CBP waveform ratio, invasive CSFp, and ABP was measured from 10 subjects with brain tumours who had a range of normal to elevated CSFp (i.e., 0-30 mmHg). Results show good agreement between the two methods (correlation r (2) = 0.55) Mean estimated CSFp for the two techniques did not show any significant difference (p > 0.05). A significant correlation between CBP pulse (CBPp) and invasive CSFp pulse (CSFpp) was observed (i.e., CSFpp = 0.0654CBBp + 3.91, p < 0.01). Estimated CSFpp was calibrated to CBPp according to this relation. In conclusion, the study demonstrated a good correlation between two different methods of estimating CSFp non-invasively and may provide a novel method to estimate CSF waveforms non-invasively.

Accuracy of combined EEG parameters in prediction the depth of anesthesia.

BACKGROUND: The importance of proper qualitative evaluation of EEG parameters during surgery has been recognized since many years. Although none of the characteristics based on the frequency, entropy, and Bi spectral characteristics have been regarded as a good predictor for detection of the depth of anesthesia alone. So it seems necessary to study multiple characteristics together. OBJECTIVES: In this study we tried to introduce the best combination of the mentioned characteristics. MATERIALS AND METHODS: EEG data of 64 patients undergoing general anesthesia with the same anesthesia protocol (total intravenous anesthesia) were recorded in all anesthetic stages in Shohada Tajrish Hospital. Quantitative EEG characteristics are classified into 4 categories: time, frequency, bi spectral and entropy based characteristics. Their sensitivity, specificity and accuracy in determination of the depth of anesthesia are yielded by comparison with recorded reference signal in awake, light anesthesia, deep anesthesia and brain death patients. Then, with combining 2, 3, 4 and 5 of characteristics and using coded algorithm we determined the error degree and introduced the combination yielding the least error. RESULTS: Fifteen vectors (of dimension two to five) which yielded the best results were introduced. Vectors combined of entropy based characteristics obtained 100% specificity and sensitivity during all 4 stages. CONCLUSIONS: The combination entropy based characteristics had high accuracy in predicting the depth of anesthesia. Reevaluation of classic indices cortical status index and BIS seems necessary. The next step is to find a system to simplify the evaluation of this information for technicians.

Presentation of a minimally symptomatic large extradural hematoma in a patient with an arachnoid cyst: a case report and review of the literature.

INTRODUCTION: Hemorrhagic complications of arachnoid cysts have been reported, extensively presenting with subdural or intracystic hematoma after trauma, but presentation with extradural hemorrhage is very rare. In this paper, we report the case of a patient with an arachnoid cyst who developed an extradural hematoma after a subtle head injury. Our patient presented with very mild symptoms in spite of the very large size of the hematoma. CASE PRESENTATION: Our patient was a 23-year-old Iranian man who complained of diffuse progressive headache and vomiting after mild head trauma. A brain computerized scan showed a very large extradural hematoma in the left frontotemporoparietal convexity over a large arachnoid cyst. CONCLUSION: Brain parenchyma containing an arachnoid cyst is vulnerable to trauma and increases the risk of serious hemorrhagic complications. We also suggest that the abnormal shape of the head should be considered as an indication for a computerized tomography scan in cases of mild head injury.

Extramedullary hematopoiesis presenting as a compressive cord and cerebral lesion in a patient without a significant hematologic disorder: a case report.

INTRODUCTION: Intracranial or spinal compressive lesions due to extramedullary hematopoiesis have been reported in the medical literature. Most of the reported cases are extradural lesions or, on rare occasions, foci within another neoplasm such as hemangioblastoma, meningioma or pilocytic astrocytoma. Often these cases occur in patients with an underlying hematological disorder such as acute myelogenic leukemia, myelofibrosis, or other myelodysplastic syndromes. Such lesions have also been reported in thalassemia major. CASE PRESENTATION: We report the case of a 43-year-old Iranian woman in whom extramedullary hematopoiesis presented as a compressive cord lesion and then later as an intracranial lesion. CONCLUSIONS: To the best of our knowledge, we document the first reported case of sacral, lumbar, thoracic and cranial involvement in the same patient with extramedullary hematopoiesis, which seems both rare and remarkable.

Lateral sacral meningocele presenting as a gluteal mass: a case report.

INTRODUCTION: Lateral meningocele is a very rare disorder. It has been reported in patients with neurofibromatosis or Marfan's syndrome. Previous reports have described lateral meningoceles in the thoracic or cervical region. Lateral meningocele in the sacral area was reported in the literature only once. CASE PRESENTATION: We describe a 3.5-year-old Iranian girl who presented with a lateral gluteal mass. Neuroimaging and intra-operative evaluation showed that the mass was a lateral sacral meningocele with spinal communication through the iliac bone. We also present a review of the literature about this entity. CONCLUSIONS: Although lateral meningoceles especially in the sacral region are rare disorders, their possibility should always be considered in young patients presenting with a paravertebral or gluteal mass.

Finite element analysis of an elastic model of the brain: distortion due to acute epidural hematoma--the role of the intra-ventricular pressure gradient.

INTRODUCTION: Recent studies on biomechanical properties of brain tissue have focused on computer simulation of this tissue during impacts, simulation of neurosurgical procedures, and improvements in navigational systems for image guided surgery. Several models have been proposed to explain the mechanical behavior of brain tissue in different conditions (dynamic, static and quasi-static), but the role of the ventricles and intra-ventricular pressure has not been studied so much, especially under static loading. It is clear that the ability of biomechanical models to predict the displacement of midline structures secondary to epidural hematoma could effectively improve the accuracy of intra-operative navigational systems. In addition, simulation of midline shift can help us to understand the mechanisms involved in pathogenesis of these conditions. Plain strain computer modeling based on finite element methods has been used to study the degree of displacement and deformation of the ventricles in acute epidural hematoma to determine the more important factors in achieving a more accurate model. MATERIALS AND METHODS: A patient with an acute epidural hematoma was used to produce a plain strain elastic model of brain tissue. The model was based on the CT data. The displacement of reference points in the modeled ventricle with changing intra-ventricular pressure gradients was compared with the displacement of similar points in the real ventricle as calculated from the CT scan, and the pressure gradients that resulted in the minimum error were determined. RESULTS: Our data showed that best results were achieved when the pressure gradient was 1.25 KPa (9.4 mm Hg). Also, the ventricle ipsilateral to the hematoma was predicted to be compressed from both the medial and lateral walls. CONCLUSION: In the plain strain biomechanical modeling of the brain in unilateral strain loading (conditions similar to those used in image guided systems), the intra-ventricular pressure gradients should be considered in order to achieve accurate results. In addition, the so-called "strain shadow effect" is emphasized.