H. Hunt Batjer and Duke S. Samson
✓ Giant paraclinoidal carotid artery aneurysms frequently require temporary interruption of local circulation to facilitate safe occlusion. Due to brisk retrograde flow through the ophthalmic artery and cavernous branches, simple trapping of the aneurysm by cervical internal carotid artery clamping and intracranial distal clipping may not adequately soften the lesion. The authors describe a retrograde suction method of aspiration of this collateral supply which they have used in over 40 cases. After temporary trapping, a No. 18 angiocatheter is inserted into the cervical internal carotid artery. This catheter is then connected to a wall suction point allowing rapid aneurysm deflation. This technique, accomplished by the surgical assistant, permits the surgeon the freedom to use both hands in dealing quickly with the aneurysm.
H. Hunt Batjer and Vin Shen Ban
This AANS presidential address focuses on enduring values of the neurosurgical profession that transcend the current political climate. The address was delivered by Dr. Batjer during a US presidential election year, but the authors have intentionally avoided discussing the current chaos of the American health care system in the knowledge that many pressing issues will change depending on the outcome of the 2016 elections. Instead, they have chosen to focus on clarifying what neurosurgeons, and the American Association of Neurological Surgeons, in particular, stand for; identifying important challenges to these fundamental principles and values; and proposing specific actions to address these challenges. The authors cite “de-professionalism” and commoditization of medicine as foremost among the threats that confront medicine and surgery today and suggest concrete action that can be taken to reverse these trends as well as steps that can be taken to address other significant challenges. They emphasize the importance of embracing exceptionalism and never compromising the standards that have characterized the profession of neurosurgery since its inception.
Phillip D. Purdy, H. Hunt Batjer and Duke Samson
✓ Endovascular embolization procedures have undergone dramatic evolution and improvement in recent years. Despite these advances, controversy remains regarding the optimal role of these procedures in treating cerebral arteriovenous malformations (AVM's) and whether their purpose should be as a presurgical adjunct or as primary therapy. This controversy risks fragmentation between disciplines in the broader efforts to improve management of cerebrovascular disorders.
The authors report seven cases of life-threatening hemorrhages that occurred during staged invasive therapy for AVM's which illustrate the value of a unified team approach to optimize patient care. Each patient underwent at least one embolization procedure using polyvinyl alcohol particles, followed in two cases by the occlusion of proximal feeding vessels by platinum microcoils and in one case by the attempted detachment of an endovascular balloon. In three patients, catheter penetration into the subarachnoid space resulted in subarachnoid hemorrhage. One patient suffered rupture of a large feeding vessel during balloon inflation. The final three patients sustained intracranial hemorrhage 2 hours, 8 hours, and 5 days, respectively, following embolization. All but two patients underwent emergency craniotomy at the time of the complication. These cases underscore the advantages of interdisciplinary management optimizing decision-making and providing expeditious care when life-threatening complications develop.
Cole A. Giller, Kurt Hodges and H. Hunt Batjer
✓ Although blood velocity in the major intracranial vessels is readily measured with transcranial Doppler ultrasound (TCD), the interpretation of velocity changes is by no means straightforward. For example, a velocity increase can arise from either a local stenosis or a decrease in downstream resistance, and these mechanisms have contradictory implications for blood flow. To determine whether TCD pulsatility might distinguish these two mechanisms, Doppler ultrasonic readings were taken from an artificial vascular model under conditions of either stenosis or distal dilation. In addition, TCD studies of nine patients with unihemispheric arteriovenous malformations (AVM's) and 16 TCD studies of seven patients with unihemispheric aneurysmal vasospasm were reviewed, and pulsatilities of the AVM's (representing decreased resistance) were compared with those of the vasospastic vessels (representing stenosis).
The average percentage drop in pulsatility in the vasodilated configuration of the model/percentage increase in velocity was 0.38 ± 0.08 (± standard error of the mean), while that for stenosis was 0.20 ± 0.01. Similar comparisons of the patient population yielded 0.67 ± 0.16 for the AVM group and 0.26 ± 0.04 for the vasospasm group. These differences were significant (p < 0.05). The fall in pulsatility associated with a given increase in velocity is significantly greater when the velocity increase arises from diminished downstream resistance than from stenosis.
M. Sean Grady, H. Hunt Batjer and Ralph G. Dacey
Postgraduate training in medicine has been under scrutiny over the past 10 years with a major focus on physician personal health and patient safety. The culmination of a series of events led to the 80-hour work week instituted by the Accreditation Council on Graduate Medical Education in 2003. The effect this mandate has had on surgical education, and specifically training in neurological surgery, has been incompletely evaluated. Nevertheless, external pressure has prompted the Institute of Medicine to issue a new report on resident work hours and patient safety.
In this report, the authors focus on the unique aspects of neurosurgical training in which physicians are trained to safely and effectively carry out complex high-risk tasks, the experience from abroad where work hours are reduced to well below 80 hours/week, and the risk that further reduction in work hours poses to the public. The authors conclude that there must be an adequate balance between the risks associated with resident fatigue and those associated with an inexperienced neurosurgical work force for public health.
Christopher S. Eddleman, H. Hunt Batjer and Sean Lavine
This issue of Neurosurgical Focus comes at an exciting and perhaps transformational time for those neuroscientists and clinicians involved in the study and treatment of complex cerebrovascular disease. Our diagnostic and therapeutic practices have seen dramatic advances. Imaging capabilities, both anatomical and functional, have improved at a dramatic rate and include neuronavigation modalities for intraoperative guidance, the application of new MR imaging sequences to cerebrovascular disease, and fluorescence angiography to aid in intraoperative decision making.
Case report and review of the literature
Stefan A. Mindea, Benson P. Yang and H. Hunt Batjer
✓The authors report on a patient harboring an unruptured cortical arteriovenous malformation (AVM), who had presented with obstructive hydrocephalus due to compression of the cerebral aqueduct by a large venous varix. Although patients with ruptured AVMs are known to either present with or later suffer from obstructive hydrocephalus, those with unruptured AVMs who present in this manner are quite rare. Moreover, hydrocephalus caused by a venous varix draining an AVM, to our knowledge, has never been previously reported in the literature. This report serves to illustrate two primary points, namely, that tortuous venous varices draining AVMs can result in obstructive hydrocephalus and that this unusual circumstance can be fostered in the setting of venous outflow obstruction.
Jing Guo, Jonathan A. White and H. Hunt Batjer
✓ To evaluate etomidate as a neuroprotective agent in the brain stem, 33 dogs were divided into seven groups and were exposed to isolated, reversible brainstem ischemia in the presence or absence of etomidate using a newly developed canine model of brainstem ischemia. Brainstem auditory evoked potentials (BAEP) and regional cerebral blood flow were measured during ischemia and for 5 hours after reperfusion. This model provides a potential physiological environment in which to test the efficacy of putative brainstem ischemic protective strategies.
During ischemia, BAEP were abolished in all animals. Without etomidate 10 minutes of ischemia was of short enough duration to allow complete recovery of BAEP. Ischemia of 20 or 30 minutes' duration resulted in minimal recovery. The dose of etomidate administered did not suppress BAEP or brainstem cardiovascular response to ischemia. In animals receiving etomidate and rendered ischemic for 20 minutes, a significant but only temporary recovery in BAEP was seen. Etomidate failed to have a significant effect in animals rendered ischemic for 30 minutes.
The minimal effect of etomidate on the current measures of brainstem function is in contrast to etomidate's known suppressive effect on cortical electroencephalogram and predicts that etomidate does little to alter brainstem metabolism. Etomidate's failure to provide for permanent recovery of BAEP suggests that the drug does not give sufficient protection from ischemia to the brainstem neurons in the auditory pathway. If these auditory neurons reflect brainstem function as a whole, etomidate may not be the protective agent of choice during temporary arterial occlusion of posterior circulation.
H. Hunt Batjer, Alan I. Frankfurt, Phillip D. Purdy, Shirley S. Smith and Duke S. Samson
✓ The operative management of large and giant aneurysms is complicated by their typically atheromatous and thick walls, frequent intramural thrombosis with calcification, and broad-based necks that often incorporate perforating and other vital vessels. Not infrequently, it is necessary to at least focally arrest the intracranial circulation and open or excise these aneurysms to facilitate vascular reconstruction. This maneuver, in patients whose disease processes have destroyed autoregulatory function or who have inadequate sources of anatomical collateral supply, may cause the threshold for permanent ischemic injury to be exceeded. The authors have recently treated 14 such patients while under electroencephalographic monitoring to document electrical burst suppression induced by the administration of etomidate, followed by temporary clipping to permit vascular repair and intraoperative angiography to document patency of parent arteries. Up to 60 minutes of internal carotid artery occlusion, 35 minutes of middle cerebral artery occlusion, 19 minutes of upper basilar artery occlusion, and 4½ minutes of lower basilar artery occlusion have been well tolerated using this protocol. In such situations, etomidate may be effective in protecting the cerebral circulation without the detrimental cardiotoxicity observed with protective doses of barbiturates.