✓ Various anatomical courses of the vertebral artery (VA) and posterior inferior cerebellar artery (PICA) have been described. The authors present a unique case of a subarachnoid hemorrhage resulting from an aneurysm in a patient with an anatomical variation of the extracranial portion of the VA and cervical origin of the PICA. The surgical implications of this variant are discussed, and the pertinent literature reviewed. Subarachnoid hemorrhage caused by rupture of a PICA aneurysm is reported for the first time in association with a rare variation of the course of the VA.
William W. Ashley Jr. and Michael R. Chicoine
William W. Ashley Jr., Sepideh Amin-Hanjani, Ali Alaraj, John H. Shin and Fady T. Charbel
✓Extracranial–intracranial bypass surgery has advanced from a mere technical feat to a procedure requiring careful patient selection and a justifiable decision-making paradigm. Currently available technologies for flow measurement in the perioperative and intraoperative setting allow a more structured and analytical approach to decision making. The purpose of this report is to review the use of flow measurement in cerebral revascularization, presenting algorithms for flow-assisted surgical planning, technique, and surveillance.
Ali Alaraj, William W. Ashley Jr., Fady T. Charbel and Sepideh Amin-Hanjani
The superficial temporal artery (STA) is the mainstay of donor vessels for extracranial–intracranial bypass in cerebral revascularization. However, the typically used STA anterior or posterior branch is not always adequate in its flow-carrying capacity. In this report the authors describe the use of the STA trunk at the level of the zygoma as an alternative donor and highlight the benefits and pitfalls of this revascularization option.
The authors reviewed the cases of 4 patients in whom the STA trunk was used as a donor site for anastomosis of a short interposition vein graft. The graft was implanted into the middle cerebral artery to trap a cartoid aneurysm in 2 patients, and the posterior cerebral artery for vertebrobasilar insufficiency in the other 2. Discrepancies in size between the interposition vein and STA trunk were compensated for by a beveled end-to-end anastomosis or by implanting the STA trunk into the vein graft in an end-to-side fashion.
Intraoperative flow measurements confirmed the significantly higher flow-carrying capacity of the STA trunk (54–100 ml/minute) compared with its branches (10–28 ml/minute). The STA trunk interposition graft has several advantages compared with an interposition graft to the cervical carotid, including a shorter graft and no need for a neck incision. However, in the setting of ruptured aneurysm trapping, with the risk of subsequent vasospasm, it is a poor conduit for endovascular therapies.
The STA trunk is a valuable donor option for cerebral revascularization, but should be avoided in the setting of subarachnoid hemorrhage.
William W. Ashley Jr., Trisha Weatherly, and Tae Sung Park
Standard brachial plexus repair techniques often involve autologous nerve graft placement and neurotization. However, when performed to treat severe injuries, this procedure can sometimes yield poor results. Moreover, harvesting the autologous graft is time-consuming and exposes the patient to additional surgical risks. To improve surgical outcomes and reduce surgical risks associated with autologous nerve graft retrieval and placement, the authors use collagen matrix tubes (Neurogen) instead of autologous nerve graft material.
Between 1991 and 2005, the authors surgically treated 65 infants who had suffered brachial plexus injury at birth. During this time, seven patients were treated using collagen matrix tubes (Neurogen). This study is a retrospective analysis of the initial five patients who were treated using the tubes. Two patients underwent tube placement recently and were excluded from the analysis because of the inadequate follow-up period.
Four of the five patients experienced a good recovery (motor scale composite [MSC] > 0.6), and three exhibited an excellent recovery (MSC > 0.75) at 2 years postoperatively. The MSC improved by an average of 69 and 78% at 1 and 2 years, respectively. The movement scores improved to greater than or equal to 50% range of motion in most patients, and the contractures were usually mild or moderate. Follow-up physical and occupational therapy evaluations confirm these patients’ functional status. When last seen, four of five of these children could feed and dress themselves.
Technically, the use of the collagen matrix tubes was straightforward and efficient, and there were no complications. The outcomes in this small series are encouraging.
William W. Ashley Jr., Jeffrey G. Ojemann, Tae Sung Park and Franz J. Wippold II
✓The authors report on a 12-year-old girl with a suprasellar mass and primary hypothyroidism in whom the lesion promptly regressed following initiation of thyroid replacement therapy. Based on this experience, it is suggested that secondary pituitary hyperplasia be included in the differential diagnostic considerations of a suprasellar lesion in a child and that resolution of the hyperplasia may occur in a matter of weeks rather than months as previously reported.
Ralph G. Dacey Jr., Gregory J. Zipfel, William W. Ashley, Michael R. Chicoine and Michael Reinert
The authors describe the use of the Cardica C-Port xA Distal Anastomosis System to perform an automated, high-flow extracranial–intracranial bypass. The C-Port system has been developed and tested in coronary artery bypass surgery for rapid distal coronary artery anastomoses. Air-powered, it performs an automated end-to-side anastomosis within seconds by nearly simultaneously making an arteriotomy and inserting 13 microclips into the graft and recipient vessel. Intracranial use of the device was first simulated in a cadaver prepared for microsurgical anatomical dissection.
The authors used this system in a 43-year-old man who sustained a subarachnoid hemorrhage after being assaulted and was found to have a traumatic pseudoaneurysm of the proximal intracranial internal carotid artery. The aneurysm appeared to be enlarging on serial imaging studies and it was anticipated that a bypass would probably be needed to treat the lesion. An end-to-side bypass was performed with the C-Port system using a saphenous vein conduit extending from the common carotid artery to the middle cerebral artery. The bypass was demonstrated to be patent on intraoperative and postoperative arteriography. The patient had a temporary hyperperfusion syndrome and subsequently made a good neurological recovery.
The C-Port system facilitates the performance of a high-flow extracranial–intracranial bypass with short periods of temporary arterial occlusion. Because of the size and configuration of the device, its use is not feasible in all anatomical situations that require a high-flow bypass; however it is a useful addition to the armamentarium of the neurovascular surgeon.
William W. Ashley Jr., Jack D. Baty, Trisha Hollander, Michael J. Noetzel and Tae Sung Park
Due to the complex and variable nature of brachial plexus injury, outcome analysis can be cumbersome and imprecise. Many scales have been devised, but no single scale is used uniformly. Moreover, despite several studies in which the authors have reported brachial plexus surgical data, no highly predictive clinical model has been defined.
In this study the authors performed a retrospective analysis of 114 consecutive brachial plexus surgeries performed by the senior author during the past 14 years at St. Louis Children's Hospital. Of these, 63 are included in this study. The authors defined the motor score composite (MSC) and used this novel metric to perform a detailed analysis of their surgical outcomes.
The mean MSC was 0.50 preoperatively, 0.71 at 1 year postoperatively, and 0.80 at 2 years postoperatively. By 2 years postoperatively, 89% of the patients attained a good or excellent recovery. Age at surgery, time to visit, location, and severity were predictive of outcome. Using MSC data, the authors developed a prognostic model that enabled the prediction (with 88% accuracy) of surgical outcomes using preoperative variables.
The MSC is an efficient metric for the reporting of data regarding outcomes of brachial plexus injury. It provides information about extent and severity of injury in a single proportion and facilitates complex data analysis. The authors used the MSC model to accurately predict surgical outcome. This metric could have wide applicability for the prediction of postoperative recovery to improve both surgical decision making and family counseling.
William W. Ashley Jr., Robert C. McKinstry, Jeffrey R. Leonard, Matthew D. Smyth, Benjamin C. Lee and Tae Sung Park
The authors examine the use of rapid-sequence magnetic resonance (rsMR) imaging to make the diagnosis of malfunctioning and/or infected shunts in patients with hydrocephalus. Computerized tomography (CT) scanning is usually used in this context because it rapidly acquires high-quality images, yet it exposes pediatric patients to particularly high levels of radiation. Standard MR imaging requires longer image acquisition time, is associated with movement artifact, and, in children, usually requires sedation. Standard MR imaging provides greater structural resolution, yet visualization of ventricular catheters is relatively poor.
The authors analyzed a series of 67 rsMR imaging examinations performed without sedation in pediatric patients with hydrocephalus whose mean age was 4 years at the time of the examination. The mean study duration was 22 minutes. Catheter visualization was good or excellent in more than 75% of studies reviewed, and image quality was good or excellent in more than 60% of studies reviewed. The authors analyzed cancer risk with a model used for atomic bomb survivors. Fifty percent of their patients with hydrocephalus had undergone more than four brain imaging studies (CT or MR imaging) in their lifetimes. For the many patients who had undergone more than 15 studies, the total estimated lifetime attributable cancer mortality risk was calculated to be at least 0.35%.
Rapid-sequence MR imaging yields reliable visualization of the ventricular catheter and offers superior anatomical detail while limiting radiation exposure. The authors' protocol is rapid and each image is acquired separately; therefore, motion artifact is reduced and the need for sedation is eliminated. They recommend the use of rsMR imaging for nonemergent evaluation of pediatric hydrocephalus.
Case report and review of the literature
William W. Ashley Jr., Prithvi Narayan, Tae Sung Park, Pang-hsien Tu, Arie Perry and Jeffrey R. Leonard
✓Juvenile xanthogranuloma (JXG) is a specialized form of non—Langerhans cell histiocyte proliferation that occurs in children. The majority of cases present as a solitary cutaneous lesion with a predilection for the head and neck region; however, isolated lesions occasionally have been identified in the central nervous system. The cutaneous forms of JXG usually follow a benign course. Other physicians have reported surgery as the first line of treatment in symptomatic patients with accessible lesions. Adjuvant therapies may be indicated for multicentric or surgically inaccessible lesions. The authors describe an unusual case of isolated intraparenchymal JXG in an asymptomatic child with no cutaneous manifestations and provide a review of the literature.
Daniel Lubelski, Roy Xiao, Debraj Mukherjee, William W. Ashley, Timothy Witham, Henry Brem, Judy Huang and Stacey Quintero Wolfe
Neurosurgery seeks to attract the best and brightest medical students; however, there is often a lack of early exposure to the field, among other possible barriers. The authors sought to identify successful practices that can be implemented to improve medical student recruitment to neurosurgery.
United States neurosurgery residency program directors were surveyed to determine the number of medical student rotators and medical students matching into a neurosurgery residency from their programs between 2010 and 2016. Program directors were asked about the ways their respective institutions integrated medical students into departmental clinical and research activities.
Complete responses were received from 30/110 institutions. Fifty-two percent of the institutions had neurosurgery didactic lectures for 1st- and 2nd-year medical students (MS1/2), and 87% had didactics for MS3/4. Seventy-seven percent of departments had a neurosurgery interest group, which was the most common method used to integrate medical students into the department. Other forms of outreach included formal mentorship programs (53%), lecture series (57%), and neurosurgery anatomy labs (40%). Seventy-three percent of programs provided research opportunities to medical students, and 57% indicated that the schools had a formal research requirement. On average, 3 medical students did a rotation in each neurosurgery department and 1 matched into neurosurgery each year. However, there was substantial variability among programs. Over the 2010–2016 period, the responding institutions matched as many as 4% of the graduating class into neurosurgery per year, whereas others matched 0%–1%. Departments that matched a greater (≥ 1% per year) number of medical students into neurosurgery were significantly more likely to have a neurosurgery interest group and formal research requirements. A greater percentage of high-matching programs had neurosurgery mentorship programs, lecture series, and cadaver training opportunities compared to the other institutions.
In recent decades, the number of applicants to neurosurgery has decreased. A major deterrent may be the delayed exposure of medical students to neurosurgery. Institutions with early preclinical exposure, active neurosurgery interest groups, research opportunities, and strong mentorship recruit and match more students into neurosurgery. Implementing such initiatives on a national level may increase the number of highly qualified medical students pursuing neurosurgery.