The devastating Venezuelan crisis

The Venezuelan crisis is filling the headlines and truly deserves the world's attention. It is a wake-up call to all as it holds relevant lessons for both developing and developed countries. The country suffers a severe humanitarian crisis. Its economy has declined at a faster pace than any other peacetime economy worldwide. Hardship and repression have led millions to flee the country creating a refugee crisis in Colombia and other neighboring countries, and millions more are expected to flee unless conditions improve. It raises serious security concerns in the whole Western Hemisphere. The country of Venezuela sits on and owns the largest oil reserves in the world. Oil helps explain the "rent-seeking" behavior that is at the root of this crisis. ("Rent-seeking" is simply getting money from the government for the oil it sells and giving little or nothing back to the government in return. -EEd) However, oil cannot be blamed for this crisis - it helped Venezuela get out of the poverty trap and become a modern democratic society in the 20^th century. This crisis comes from the perverse combination of bad politics, bad policy, and corruption that besieged the country over the last 20 years. Since he was elected in 1998, Hugo Chávez paved the way to authoritarianism while making the economy more vulnerable to the ups and downs of oil prices. Chávez died in early 2013. When Nicolás Maduro, his anointed heir, was elected to succeed him, the economy was in bad shape and institutions were already weak, but problems had been papered over thanks to high oil prices and the money the government made from its sale. When oil prices were high worldwide, Venezuelan governments did not save money for possible future economic losses. When oil prices began falling in 2014 and threatened the money from "rent-seeking" by many Venezuelans, Maduro chose the road to overt authoritarianism instead of seeking to restore the basics of an open society and a prosperous economy: the rule of law, property rights, transparency, prudent fiscal and monetary policy, and essential public goods such as education, health, housing, transportation, and infrastructure. This paper is a brief history of how the present Crisis in Venezuela developed and how it can be reasonably resolved. The Venezuelan people are suffering. There are lessons here for everyone in the world (A Venezuelan and James Ausman).

Cerebral and somatic venous oximetry in adults and infants

Background:

The development in the last decade of noninvasive, near infrared spectroscopy (NIRS) analysis of tissue hemoglobin saturation in vivo has provided a new and dramatic tool for the management of hemodynamics, allowing early detection and correction of imbalances in oxygen delivery to the brain and vital organs.

Description:

The theory and validation of NIRS and its clinical use are reviewed. Studies are cited documenting tissue penetration and response to various physiologic and pharmacologic mechanisms resulting in changes in oxygen delivery and blood flow to the organs and brain as reflected in the regional hemoglobin oxygen saturation (rSO₂). The accuracy of rSO₂ readings and the clinical use of NIRS in cardiac surgery and intensive care in adults, children and infants are discussed.

Conclusions:

Clinical studies have demonstrated that NIRS can improve outcome and enhance patient management, avoiding postoperative morbidities and potentially preventing catastrophic outcomes.

Follow-up angiography of intracranial aneurysms treated with endovascular placement of Guglielmi detachable coils

OBJECTIVE

The success of endovascular treatment of intracranial aneurysms with Guglielmi detachable coils (GDCs) is dependent on the long-term exclusion of the aneurysm from the circulation. We reviewed our experience with the long-term angiographic follow-up monitoring of aneurysms that had been treated with GDCs.

METHODS

All patients whose aneurysms had been treated with GDCs between January 1995 and August 1999 and who subsequently underwent follow-up angiography at 6 months or more were included in this study. We reviewed all of the angiographic findings, to determine the percentage of aneurysm occlusion on the initial angiograms and on the last available follow-up angiograms. The categories of aneurysm occlusion used were 100%, >or=95%, and less than 95% occlusion.

RESULTS

One hundred thirty patients with 141 aneurysms underwent 143 endovascular coiling procedures and subsequently underwent angiographic follow-up monitoring of 6 months or more. There were 102 female and 28 male patients. The mean angiographic follow-up period was 16.7 months (range, 6-62 mo). The initial rates of occlusion were 100% for 56 aneurysms (39%), >or=95% for 65 aneurysms (46%), and less than 95% for 22 aneurysms (15%). Recurrence of one aneurysm (1.8%) was observed. Of the 87 aneurysms that were incompletely occluded initially, there was progressive thrombosis in 40 (46%), stable neck remnants in 23 (26%), and enlargement of the residual neck in 24 (28%). The final occlusion rates, determined on the last available angiograms, were 100% for 88 aneurysms (61%), >or=95% for 31 aneurysms (22%), and less than 95% for 24 aneurysms (17%). No patient experienced repeat or new subarachnoid hemorrhage more than 6 months after the initial treatment.

CONCLUSION

Late angiographic follow-up monitoring of aneurysms that have been treated with GDCs demonstrates the durability of the treatment. Aneurysms with large residual neck remnants were subjected to further treatment, whereas aneurysms with small residual neck remnants remain under observation.

Contemporary management of subarachnoid hemorrhage and vasospasm: the UIC experience

BACKGROUND

Cerebral vasospasm is a well-known and serious complication of aneurysmal subarachnoid hemorrhage. The means of monitoring and treatment of vasospasm have been widely studied. Each neurosurgical center develops a protocol based on their experience, availability of equipment and personnel, and cost, so as to keep morbidity and mortality rates as low as possible for their patients with vasospasm.

METHODS

At the University of Illinois at Chicago, we have developed algorithms for the diagnosis and management of cerebral vasospasm based on the experience of the senior authors over the past 25 years. This paper describes in detail our approach to diagnosis and treatment of aneurysmal subarachnoid hemorrhage and vasospasm. Our discussion is highlighted with data from a retrospective analysis of 324 aneurysm patients.

RESULTS

Over 3 years, 324 aneurysms were treated; 185 (57%) were clipped, 139 (43%) were coiled. The rate of vasospasm for the 324 patients was 27%. The rate of hydrocephalus was 32% for those patients who underwent clipping, and 29% for those coiled. The immediate outcomes for those who underwent clipping was excellent in 35%, good in 38%, poor in 15.5%, vegetative in 3%, and death in 8% of the patients. For those who underwent coiling the immediate outcome was excellent in 64%, good in 14.5%, vegetative in 2.5%, and death in 14.5% of the patients. These statistics include all Hunt and Hess grades. For those patients who underwent clipping, 51% were intact at 6 months follow-up, 15% had a permanent deficit, 10% had a focal cranial nerve deficit, and 2% had died from complications not directly related to the procedure. For those patients who had undergone coiling, 75% were intact at 6 months follow-up, 12.5% had a permanent deficit, and 12.5% had a cranial nerve deficit, with no deaths.

CONCLUSIONS

The morbidity and mortality of cerebral vasospasm is significant. A good outcome after aneurysmal subarachnoid hemorrhage is dependent upon careful patient management in the preoperative, perioperative, and postoperative periods. The timely work-up and aggressive treatment of neurological deterioration, whether or not it is because of vasospasm, is paramount.

Glued Catheters during Embolisation of Brain AVMs with Acrylic Glue

SUMMARY

We evaluated the frequency and the side effects associated with gluing a piece of microcatheter in the feeder during embolisation of brain AVMs with acrylic glue. A retrospective analysis of 233 brain AVMs embolised with acrylic glue over a 15 year period has shown that 29 microcatheters were glued into the feeder. This represents 936 superselective catheterizations of different feeders followed by injection of glue. There was no side effect in 27 cases. Eight cases were operated upon a few hours or days after the complication occurred. The piece of tubing was removed in six cases. The reason for early surgery was the fear of extensive thrombosis of a major trunk (MCA or BA) or taking advantage of the catheter being still free in the cerebral vessel. In one case of temporal AVM, a Magic 1.5F coiled up into the distal basilar and PCA. In one case of left parietotemporal AVM, surgery was done one month after having glued a piece of tubing into the left MeA without side effect. The patient became hemiplegic and aphasic two hours after surgery. The thrombosed left MeA was reopened with Urokinase. The patient recovered with minor residual aphasia. The risk of side effects increases with the use of the Magic 1.5F that coils up into the vessel more easily than the Magic 1.8F. Leaving a piece of Magic catheter in the feeder to a brainAVM usually has no side effect. When there is a risk of thrombosis of a major trunk (MCA, BA) or when surgical resection is indicated, surgery should be done as soon as possibile because it is usually possible and easy to retrieve the piece of tubing from the intracranial circulation. The frequency of this complication has decreased since we starded using more diluted acrylic glue.

Direct cervical internal carotid access for GDC treatment of an ophthalmic origin carotid aneurysm

The use of detachable coils in the treatment of intracranial aneurysms continues to evolve since its introduction in 1991 [1-5]. Although not well described in the literature, technical considerations in gaining and maintaining access to intracranial aneurysms play a pivotal role in any successful endovascular treatment. Tortuosity and looping of the cervical internal carotid artery (ICA) is one problem occasionally encountered. These unusual loops, in addition to the normal turns of the carotid siphon result in less control of the microcatheter tip. This problem culminated in this case where an ophthalmic origin carotid aneurysm could not be successfully treated from the standard femoral approach due to the presence of multiple ICA turns, with the presence of a proximal cervical ICA turn being particularly bothersome. This problem was circumvented by use of direct surgical access to the cervical ICA above the cervical ICA turn, allowing for successful endovascular aneurysm treatment with detachable coils.

Angiography and treatment of a pial occipital malformation supplied by a posterior temporo-occipital branch of the anterior choroidal artery

The anterior choroidal artery rarely supplies the posterior temporal and occipital lobes. We describe such an anatomical variation association with an arteriovenous malformation of the occipital lobe.

Determination of regional cerebral oxygen consumption in the human: 17O natural abundance cerebral magnetic resonance imaging and spectroscopy in a whole body system

17O natural abundance imaging in a whole body imager is demonstrated using standard MRI spectrometer and 1H imaging methods. A novel design of a highly sensitive 17O/1H doubly tuned surface head coil is shown. The head probe allows simultaneous acquisition of 17O and 1H images using a single coil. The relatively low 17O signal intensity due to the low natural abundance of 17O (0.037 atom percent) is partially compensated by fast repetition of the pulse sequence, achievable due to the short spin lattice relaxation time, T1. A small number of signal averages (e.g., NEX = 50) is sufficient for obtaining images having signal to noise of about 5:1. Due to the short longitudinal relaxation time of 17O, i.e., 2-5 msec, short TR values can be used. 128 phase encoding steps with TR = 10-25 msec correspond to total acquisition time of 1 to 2.5 min. Due to the small gyromagnetic ratio of 17O and the relatively small gradients in a standard whole body system, i.e. 0.5 G/cm, the image in-plane resolution is about 3 mm and a slice thickness of 15 mm. In vivo 17O MRS and MRI natural abundance spectroscopic signals and images of human brain have been observed. The transverse relaxation time, T2 was found to be 2.00 +/- 0.17 msec at 1.5 T. MRS 17O measurements of signal intensity in the occipital cortex during inhalation of oxygen gas, 21.8% 17O enriched, showed a maximum signal enhancement of 25% within the inhalation period. The rate of the metabolism of oxygen (CMRO2) in the occipital cortex was found to be 1.5 mumole/(g tissue) in good agreement with the value of 1.435 mumole/(g tissue) given in the literature. Current measurements using higher 17O enrichments and larger quantities of 17O enriched oxygen gas will enhance resolution and provide more accurate determination of the rate of oxygen metabolism rate and blood flow. The potential of 17O imaging is thus demonstrated in physiological in vivo studies of cerebral metabolism of oxygen and blood flow.

Stereotactic endoscopic interventions in cystic and intraventricular brain lesions

Image guided stereotaxis is an accurate and safe method of directing therapy to target volumes defined in two-dimensional (2D) multiplanes or three-dimensional (3D) perspectives using computer reconstruction of image data. The major limitations of stereotactic techniques are related to a lack of intraoperative visualization and direct monitoring of the procedures and to changes of intracranial coordinates after decompression of cystic lesions or aspiration of cerebrospinal fluid in the management of intraventricular lesions. Endoscopic laser stereotaxis (ELS) involves integration of rigid-flexible endoscopy and Nd-YAG laser to 3D-2D multiplanar image-guided stereotactic procedures. The major advantages of ELS include: direct intraoperative visualization, hemostasis, evacuation or resection assessment, and wide exploration of intracranial cavities or ventricles. The technique allows safe aspiration, biopsy, and resection or internal decompression of deep and subcortical intracranial lesions. ELS has proved to be safe and effective in the management of 76 clinical cases and appears to be a promising technique in the management of cystic and intraventricular lesions.

Application of multimodality imaging stereotactic localization in the surgical management of vascular lesions

Multidimensional image preplanning and accurate pre and intraoperative localization for intracranial vascular lesions have been implemented. Methodology include carbon fiber base ring, localizer plates, any X-ray tubes, PC compatible software and intraoperative localizing unit. Surgical management of deep arteriovenous malformations is especially suitable for this technique, including the use of intraoperative digital angiography.

Image-guided stereotactic centered craniotomy and laser resection of solid intracranial lesions

A technique in which solid intracranial lesions are removed using computerized image processing under stereotactic conditions is described. A specially developed carbon fiber ring holder compatible with most image studies is used as a reference system. Intraoperatively it affords freedom of patient positioning and unobstructed access to any site of the head. Four position alternatives of the aiming device allow the removal of lesions from any location. For superficial lesions located near eloquent areas, a 'centered' craniotomy is performed, usually under local anesthesia, and removal is performed using loupe magnification, bipolar coagulation ultrasonic aspiration of the Nd:YAG laser fiber in the contact or noncontact technique. In deep-seated lesions, a surgical 'corridor' is established and kept by means of retractors adapted for use with the stereotactic apparatus. Microsurgical techniques and the CO2 laser are used in solid lesions; in vascular lesions, bipolar coagulation or the ND:YAG laser can be used. Centered craniotomy allows the precise localization, enhancement, three-dimensional orientation and removal of lesions with minimal trauma to the surrounding brain. The technique has been applied in 78 cases where the extreme accuracy of the technique, benign postoperative course and short hospitalization have been impressive.