Santiago Cepeda

Basic Principles of Hemodynamics and Cerebral Aneurysms.

BACKGROUND Rupture is the most serious consequence of cerebral aneurysms, and its likelihood depends on nonmodifiable and modifiable risk factors. Recent efforts have focused on analyzing the effects of hemodynamic forces on the initiation, growth, and rupture of cerebral aneurysms. Studies of the role of hemodynamics in the physiopathology of intracranial aneurysms fall between mechanical engineering and molecular biology. METHODS This review summarizes the basic principles of the effect of hemodynamic forces on the cerebral vascular wall. CONCLUSIONS The size of the aneurysm dome is the most common parameter used in clinical practice to estimate the risk of rupture. However, relying only on aneurysm size means excessively simplifying a more complicated reality. Aneurysms emerge in areas of the vascular wall exposed to high wall shear stress. The direction in which blood flows once an aneurysm forms depends on aspects such as neck diameter, its angle with respect to the parent artery, the parent vessel caliber, the caliber or the angle of efferent vessels, and aneurysm shape. The progression and rupture of aneurysms have been associated with zones of the aneurysm wall exposed to both high and low wall shear stresses. Advances in this challenging and growing field are intended to predict more precisely the risk of rupture of aneurysms and to better understand the mechanisms of origin and growth of aneurysms.

Cranioplasty after decompressive craniectomy. A prospective series analyzing complications and clinical improvement.

BACKGROUND Cranioplasty is carried out for cosmetic reasons and for protection, but it may also lead to some neurological improvement after the bone flap placement. Complications of cranioplasty are more frequent than expected for a scheduled neurosurgical procedure. We tried to identify factors associated with both complications and improvement after cranioplasty. METHODS We prospectively studied the cranioplasties performed in our hospital from November 2009 to November 2013. Patients whose initial reason for bone removal was tumor infiltration were excluded. Demographic, clinical and radiological data were collected. The NIH Stroke Scale and Barthel Self-Care Index scores were obtained both before and within 72 h after cranioplasty. The outcome measures were the occurrences of complications and clinical improvement. RESULTS Fifty-five cranioplasties were performed. The material used for the cranioplasty was autologous bone in 42 cases, polyetheretherketone (PEEK) in 7 and methacrylate in 6. The average size of the bone defect was 69.5 (19.5-149.5) cm2. The time elapsed between decompressive craniectomy and cranioplasty was 309 (25-1217) days. There were 10 complications (7 severe and 3 mild), an 18.2% complication rate. Statistically significant risk factors of complications were identified as a Barthel≤70 (Odds ratio [OR] 22; 2.5-192; P=0.005), age over 45 years (OR 13.5; 1.5-115; P=0.01) and early surgery (≤85 days; OR 8; 1.69-37.03, P=0.004). After multivariate analysis, Barthel≤70 and age over 45 years remained independent predictors of complications. Twenty-two (40%) of the 55 patients showed objective improvement. Early surgery (<85 days) increased the likelihood of improvement (OR 4.67; 1.05-20.83; P=0.035). Larger bone defects seemed to be related with improvement, but differences in defect size were not statistically significant (75.3 vs 65.6 cm2; P=0.1). CONCLUSIONS The complication rate of cranioplasty is higher than for other elective neurosurgical procedures. Older age, poorer functional situation (worse Barthel index score) and early surgery (≤85 days) are independent risk factors for complications. However, cranioplasty produces clinical benefits beyond protection and esthetic improvement. Earlier surgery and larger bone defects seem to increase the likelihood of clinical improvement.

Contrecoup Traumatic Intracerebral Hemorrhage: A Geometric Study of the Impact Site and Association with Hemorrhagic Progression

Traumatic intracerebral hemorrhage (TICH) represents 13-48% of the lesions after a traumatic brain injury (TBI). The frequency of TICH-hemorrhagic progression (TICH-HP) is estimated to be approximately 38-63%. The relationship between the impact site and TICH location has been described in many autopsy-based series. This association, however, has not been consistently demonstrated since the introduction of computed tomography (CT) for studying TBI. This study aimed to determine the association between the impact site and TICH location in patients with moderate and severe TBI. We also analyzed the associations between the TICH location, the impact site, the production mechanism (coup or contrecoup), and hemorrhagic progression. We retrospectively analyzed the records of 408 patients after a moderate or severe TBI between January 2010 and November 2014. We identified 177 patients with a total of 369 TICHs. We found a statistically significant association between frontal TICHs and impact sites located on the anterior area of the head (OR 5.8, p < 0.001). The temporal TICH location was significantly associated with impact sites located on the posterior head area (OR 4.9, p < 0.001). Anterior and lateral TICHs were associated with impact sites located at less than 90 degrees (coup) (OR 1.64, p = 0.03) and more than 90 degrees (contrecoup), respectively. Factors independently associated with TICH-HP obtained through logistic regression included an initial volume of <1 cc, cisternal compression, falls, acute subdural hematoma, multiple TICHs, and contrecoup TICHs. We demonstrated a significant association between the TICH location and impact site. The contrecoup represents a risk factor independently associated with hemorrhagic progression.

Spinal Cord Injury after Blunt Cervical Spine Trauma: Correlation of Soft-Tissue Damage and Extension of Lesion

This study retrospectively evaluates whether ligamentous injury or disk disruption after spinal cord injury correlates with lesion length. Length of lesion, disk disruption, ligamentous injury association, and extent of spinal cord injury were statistically assessed. The number of ligaments affected had a positive correlation with the extension of the lesion. Thus, in cervical spine trauma, a specific pattern of ligamentous injury correlates with the length of the spinal cord lesion. BACKGROUND AND PURPOSE: In patients with spinal cord injury after blunt trauma, several studies have observed a correlation between neurologic impairment and radiologic findings. Few studies have been performed to correlate spinal cord injury with ligamentous injury. The purpose of this study was to retrospectively evaluate whether ligamentous injury or disk disruption after spinal cord injury correlates with lesion length. MATERIALS AND METHODS: We retrospectively reviewed 108 patients diagnosed with traumatic spinal cord injury after cervical trauma between 1990–2011. Plain films, CT, and MR imaging were performed on patients and then reviewed for this study. MR imaging was performed within 96 hours after cervical trauma for all patients. Data regarding ligamentous injury, disk injury, and the extent of the spinal cord injury were collected from an adequate number of MR images. We evaluated anterior longitudinal ligaments, posterior longitudinal ligaments, and the ligamentum flavum. Length of lesion, disk disruption, and ligamentous injury association, as well as the extent of the spinal cord injury were statistically assessed by means of univariate analysis, with the use of nonparametric tests and multivariate analysis along with linear regression. RESULTS: There were significant differences in lesion length on T2-weighted images for anterior longitudinal ligaments, posterior longitudinal ligaments, and ligamentum flavum in the univariate analysis; however, when this was adjusted by age, level of injury, sex, and disruption of the soft tissue evaluated (disk, anterior longitudinal ligaments, posterior longitudinal ligaments, and ligamentum flavum) in a multivariable analysis, only ligamentum flavum showed a statistically significant association with lesion length. Furthermore, the number of ligaments affected had a positive correlation with the extension of the lesion. CONCLUSIONS: In cervical spine trauma, a specific pattern of ligamentous injury correlates with the length of the spinal cord lesion in MR imaging studies. Ligamentous injury detected by MR imaging is not a dynamic finding; thus it proved to be useful in predicting neurologic outcome in patients for whom the MR imaging examination was delayed.

The Effect of Cranioplasty on Cerebral Hemodynamics as Measured by Perfusion Computed Tomography and Doppler Ultrasonography

Cranioplasties are performed to protect the brain and correct cosmetic defects, but there is growing evidence that this procedure may result in neurological improvement. We prospectively studied cranioplasties performed at our hospital over a 5-year period. The National Institute of Health Stroke Scale and Barthel index were recorded prior to and within 72 h after the cranioplasty. A perfusion computed tomography (PCT) and transcranial Doppler sonography (TCDS) were performed prior to and 72 h after the surgery. For the PCT, regions irrigated by the anterior cerebral artery, the middle cerebral artery (MCA), the posterior cerebral artery, and the basal ganglia were selected, as well as the mean values for the hemisphere. The sonography was performed in the sitting and the supine position for the MCA and internal carotid. The velocities, pulsatility index, resistance index, and Lindegaard ratio (LR) were obtained, as well as a variation value for the LR (ΔLR = LR sitting - LR supine). Fifty-four patients were included in the study. Of these, 23 (42.6%) patients presented with objective improvement. The mean cerebral blood flow of the defective side (m-CBF-d) increased from 101.86 to 117.17 mL/100 g/min (p = 0.064), and the m-CBF of the healthy side (m-CBF-h) increased from 128.14 to 145.73 mL/100 g/min (p = 0.028). With regard to the TCDS, the ΔLR was greater on the defective side prior the surgery in those patients who showed improvement (1.295 vs. -0.714; p = 0.002). Cranioplasty resulted in clinical improvement in 40% of the patients, with an increase in the post-surgical CBF. The larger variations in the LR when the patient is moved from the sitting to the supine position might predict the clinical improvement.

Prognostic Value of the Amount of Bleeding After Aneurysmal Subarachnoid Hemorrhage: A Quantitative Volumetric Study.

BACKGROUND Quantitative estimation of the hemorrhage volume associated with aneurysm rupture is a new tool of assessing prognosis. OBJECTIVE To determine the prognostic value of the quantitative estimation of the amount of bleeding after aneurysmal subarachnoid hemorrhage, as well the relative importance of this factor related to other prognostic indicators, and to establish a possible cut-off value of volume of bleeding related to poor outcome. METHODS A prospective cohort of 206 patients consecutively admitted with the diagnosis of aneurysmal subarachnoid hemorrhage to Hospital 12 de Octubre were included in the study. Subarachnoid, intraventricular, intracerebral, and total bleeding volumes were calculated using analytic software. For assessing factors related to prognosis, univariate and multivariate analysis (logistic regression) were performed. The relative importance of factors in determining prognosis was established by calculating their proportion of explained variation. Maximum Youden index was calculated to determine the optimal cut point for subarachnoid and total bleeding volume. RESULTS Variables independently related to prognosis were clinical grade at admission, age, and the different bleeding volumes. The proportion of variance explained is higher for subarachnoid bleeding. The optimal cut point related to poor prognosis is a volume of 20 mL both for subarachnoid and total bleeding. CONCLUSION Volumetric measurement of subarachnoid or total bleeding volume are both independent prognostic factors in patients with aneurysmal subarachnoid hemorrhage. A volume of more than 20 mL of blood in the initial noncontrast computed tomography is related to a clear increase in poor outcome risk. ABBREVIATION : aSAH, aneurysmal subarachnoid hemorrhage.

Endovascular treatment of a true posterior communicating artery aneurysm

Background: Posterior communicating artery (PCoA) aneurysms are most commonly located at the junction of the internal carotid artery and the PCoA. “True” PCoA aneurysms, which originate from the PCoA itself, are rarely encountered. Most previously reported cases were treated surgically mainly before the endovascular option became available. Case Description: A 53-year-old male presented with sudden onset of right hemiparesis and aphasia. Left middle cerebral artery stroke was diagnosed. Further studies revealed a 3 mm left PCoA aneurysm arising from the PCoA itself, attached to neither the internal carotid artery nor the posterior cerebral artery. Endovascular treatment was performed and the aneurysm was coiled completely. Conclusion: Technical advances in endovascular interventional technology have permitted an additional approach to these lesions. The possible endovascular significance of the treatment of true PCoA aneurysms is discussed.

MRI Prognostication Factors in the Setting of Cervical Spinal Cord Injury Secondary to Trauma

OBJECTIVE Several studies have looked for an association between radiologic findings and neurologic outcome after cervical trauma. In the current literature, there is a paucity of evidence proving the prognostic role of soft tissue damage or bony integrity. Our objective is to determine radiologic findings related to neurologic prognosis in patients after incomplete acute traumatic cervical spinal cord injury, regardless of initial neurologic examination results. METHODS We retrospectively reviewed patients with acute traumatic cervical spinal cord injury who had a magnetic resonance imaging (MRI) performed within the first 96 hours. Clinical and epidemiologic data were recorded from the medical records along with several radiologic findings from the initial computed tomographic scan and MRI. Data were analyzed using a non-parametric test. Significant prognostic factors were analyzed through a stepwise multivariable logistic regression, adjusted by neurologic status at baseline. The receiver-operating characteristic curve was used to test the discriminative capacity of the model. RESULTS Eighty-six patients (68 males and 18 females) were included for the analysis. Mean age was 49 years. Ligamentum flavum injury, intramedullary edema larger than 36 mm, and facet dislocation were demonstrated to be associated with a lack of neurologic improvement at follow-up. Multivariable analysis showed that edema larger than 36 mm and facet dislocation were strong predictors of clinical outcome, regardless of the initial neurologic examination result. CONCLUSION Early MRI has an intrinsic prognostic value. Ligamentous injury and larger edema are strong predicting factors of a bad neurologic outcome at long-term follow-up.

Symptomatic ptosis cerebelli after suboccipital craniectomy in a patient with severe brain trauma

ABSTRACT Primary objective: To report the first case of symptomatic cerebellar ptosis after a large suboccipital craniectomy in a patient with severe brain trauma and a review of the literature. Patient and methods: A 36-year-old man suffered severe traumatic brain injury after a four-metre fall. He underwent a large suboccipital craniectomy because his computed tomography scan revealed a posterior fossa subdural haematoma and cerebellar swelling. Four weeks after admission, he developed communicating hydrocephalus, and a ventriculoperitoneal shunt was placed. Although he experienced good recovery, seven months after the trauma he complained of cephalea, dizziness, recurrent vomiting and diplopia. Magnetic resonance imaging (MRI) showed descent of the cerebellum through a wide bone defect. Results: We performed a posterior fossa cranioplasty after other causes of delayed worsening were ruled out, such as shunt malfunction, overdrainage and ischaemic lesions. The patient improved, and a post-operative MRI confirmed the upward migration of the cerebellum. Conclusions: Cerebellar ptosis must be considered in cases of delayed symptoms after large suboccipital craniectomy regardless of pathology. Posterior fossa cranioplasty to provide structural support to slumped cerebellum can improve or resolve symptoms.