Research

Neurosurgical Residency Away Rotation

Neurosurgical Residency Away Rotation

Neurosurgical Residency Away Rotation is an important component in the education of a neurosurgical resident. Subspecialization of physicians and regional centers concentrate the volume of certain rare cases into fewer hospitals. Consequently, the primary institution of a Neurosurgical Resident Training Program may not have sufficient case volume to meet the current Residency Review Committee case minimum requirements in some areas. To ensure the competency of graduating residents through comprehensive neurosurgical education, programs may need residents to travel to outside institutions for exposure to cases that are either less common or more regionally focused.

Harvey Williams Cushing 14-month Wanderjahr had a profound effect on his subsequent personal career, which in turn ushered in the modern age of American neurosurgery. From July 1900 to August 1901, he traveled to European neurosurgical centers in England, France, Switzerland, Italy, and Germany. His excursion happened at a crucial moment in his trajectory; it was built on his existing foundation of Halstedian surgical training and occurred at a time when interest in the special field of neurological surgery was emerging. The research and clinical experiences on his journey-good and bad-undoubtedly informed his fledgling neurosurgical practice. Salwi et al. present a concise account of Harvey Cushing’s time in Europe that consolidates accounts from Cushing’s travel journals, biographers, and other neurosurgeons.

The article of Salwi et al. highlights tensions in prior works and reveals new insights into the transformative nature of his Wanderjahr. Furthermore, he contextualizes his travels and achievements within the broader transformation of American medical education at the turn of the 20th century to elucidate how Europe influenced American medicine. They briefly consider the parallel benefits of Harvey Cushing’s Wanderjahr and modern domestic or international training opportunities and present potential areas of implementation 1)

Selection of the area of research

The selection of the area of research is essential. There are many arguments in favor of selecting research projects to be close to the individual trainee‘s clinical interest. Studies far away from the individual’s clinical interest in most cases are less productive and will not be pursued later. There are also many advantages if cooperation is planned with other institutions. The residency program director or staff members play an important role in the selection of the research project, of an appropriate laboratory or institution, and in the process of financing a research rotation 2)

Advantages

A neurosurgical residency away rotation allows a neurosurgical resident to spend time at another institution, usually for several weeks or months, to gain additional experience and training in the field of neurosurgery. Some potential benefits of a neurosurgical away rotation may include:

Exposure to a different patient population: Away rotations can expose neurosurgical residents to a different patient population, which may help broaden their clinical skills and experience.

Exposure to different surgical techniques and approaches: The host institution may use different surgical techniques and approaches than the resident’s home institution, which can broaden the resident’s skill set and knowledge of neurosurgery.

Access to specialized equipment and resources: The host institution may have access to specialized equipment or resources that are not available at the resident’s home institution. This can provide a unique learning opportunity and exposure to cutting-edge technology.

Networking opportunities: Away rotations provide opportunities to build relationships with faculty members, residents, and other medical professionals at the host institution. This can be valuable for future job opportunities or collaborations.

Improved residency application: Completing an away rotation at a program of interest can provide neurosurgical residents with an opportunity to showcase their skills and abilities, potentially improving their chances of being accepted into the program.

Overall, a neurosurgical residency away rotation can provide valuable learning experiences, networking opportunities, and exposure to different clinical scenarios and surgical techniques, which can help to enhance the skills and knowledge of neurosurgical residents.

Disadvantages

While there are many potential benefits to a neurosurgical residency away rotation, there are also some potential disadvantages to consider. These may include:

Disruption of continuity of care: When neurosurgical resident is away from their home institution, they may miss out on some aspects of patient care and continuity of care. This can lead to challenges in communication and follow-up for patients.

Potential differences in practice style: The host institution may have different practice styles, expectations, or protocols than the resident’s home institution. This can create confusion or challenges for the resident in terms of adapting to a new environment and different expectations.

Financial costs: Neurosurgical residents may need to bear the costs of travel, lodging, and other expenses associated with completing an away rotation. This can be a significant financial burden, particularly for residents with limited financial resources.

Challenges adapting to a new environment: Moving to a unique institution, even temporarily, can be stressful and challenging for neurosurgical residents. They may need to adapt to new living arrangements, a new hospital system, and new colleagues.

Limited time for exploration: While an away rotation can provide exposure to a different patient population and clinical setting, the limited amount of time can make it difficult to fully explore and understand the nuances of the institution and its practice.

Overall, a neurosurgical residency away rotation can be a valuable experience, but residents should carefully consider the potential disadvantages before making the decision to participate. It’s important to weigh the potential benefits against the costs and challenges to determine if an away rotation is a right choice for the individual resident.

ACGME rules regarding away rotations

Gephart et al. sought to evaluate off-site rotations to better understand the changing demographics and needs of resident education. This would also allow prospective monitoring of modifications to the neurosurgery training landscape. They completed a survey of neurosurgery program directors and a query of data from the Accreditation Council of Graduate Medical Education to characterize the current use of away rotations in the neurosurgical education of residents. They found that 20% of programs have mandatory away rotations, most commonly for exposure to a pediatric, functional, peripheral nerve, or trauma cases. Most of these rotations are done during postgraduate years 3 to 6, lasting 1 to 15 months. Twenty-six programs have 2 to 3 participating sites and 41 have 4 to 6 sites distinct from the host program. Programs frequently offset potential financial harm to residents rotating at a distant site by the support of housing and transportation costs. As medical systems experience fluctuating treatment paradigms and demographics, over time, more residency programs may adapt to meet the Accreditation Council of Graduate Medical Education case minimum requirements through the implementation of away rotations 3).

In 2019, the ACGME implemented new rules regarding away rotations, in an effort to promote resident well-being, reduce the burden of travel and expense associated with away rotations, and improve the quality of the educational experience for residents. Under these new rules, the ACGME now requires that:

Residency programs must limit the number of away rotations to no more than four weeks per year, per resident. Programs must have a written policy that outlines the process for selecting and approving away rotations, and must ensure that residents receive appropriate supervision and support during their away rotations. Programs must ensure that away rotations do not interfere with resident education and training, and that residents have adequate time to meet program requirements and prepare for board exams. The ACGME’s requirements related to away rotations are part of a larger effort to improve the quality of graduate medical education in the United States, and to ensure that residents receive the training and support they need to become competent and compassionate physicians.

1)

Salwi S, Chitale RV, Kelly PD. Harvey Cushing’s Wanderjahr (1900-1901). World Neurosurg. 2020 Oct;142:476-480. doi: 10.1016/j.wneu.2020.07.034. Epub 2020 Jul 19. PMID: 32698081; PMCID: PMC8048037.
2)

Reulen HJ. Basic research vs. applied research. Acta Neurochir Suppl. 2002;83:45-8. doi: 10.1007/978-3-7091-6743-4_8. PMID: 12442620.
3)

Gephart MH, Derstine P, Oyesiku NM, Grady MS, Burchiel K, Batjer HH, Popp AJ, Barbaro NM. Resident away rotations allow adaptive neurosurgical training. Neurosurgery. 2015 Apr;76(4):421-5; discussion 425-6. doi: 10.1227/NEU.0000000000000661. PMID: 25635889.

Vancomycin

Vancomycin

Vancomycin is a glycopeptide antibiotic medication.

Blood levels may be measured to determine the correct dose.

When taken by mouth it is poorly absorbed.

Vancomycin Cerebrospinal Fluid Pharmacokinetics

A study described the cerebrospinal fluid (CSF) exposure of vancomycin in 8 children prescribed intravenous vancomycin therapy for cerebral ventricular shunt infection. Vancomycin CSF concentrations ranged from 0.06 to 9.13 mg/L and the CSF: plasma ratio ranged from 0 to 0.66. Two of 3 children with a staphylococcal CSF infection had CSF concentrations greater than the minimal inhibitory concentration at the end of the dosing interval 1).

Cerebrospinal fluid (CSF) penetration and the pharmacokinetics of vancomycin were studied after continuous infusion (50 to 60 mg/kg of body weight/day after a loading dose of 15 mg/kg) in 13 mechanically ventilated patients hospitalized in an intensive care unit. Seven patients were treated for sensitive bacterial meningitis and the other six patients, who had a severe concomitant neurologic disease with intracranial hypertension, were treated for various infections. Vancomycin CSF penetration was significantly higher (P < 0.05) in the meningitis group (serum/CSF ratio, 48%) than in the other group (serum/CSF ratio, 18%). Vancomycin pharmacokinetic parameters did not differ from those obtained with conventional dosing. No adverse effect was observed, in particular with regard to renal function 2).

Ichinose et al. evaluated the concentration of Vancomycin in the plasma and CSF of postoperative neurosurgical patients with bacterial meningitis and evaluated the factors that affect the transferability of VCM to CSF. The concentrations of VCM in plasma (trough) and CSF were determined in eight patients (four males and four females) with bacterial meningitis who were treated with VCM using High-performance liquid chromatography. The ratio of the VCM concentrations in CSF/plasma was also calculated by estimating the blood VCM concentration at the same time as the VCM concentration in CSF was measured. The results showed that the VCM concentration in CSF was 0.9-12.7 µg/mL and the CSF/plasma VCM concentration ratio was 0.02-0.62. They examined the effect of drainage on the transferability of VCM to CSF, which showed that the VCM concentration in CSF and the CSF/plasma VCM concentration ratio were significantly higher in patients not undergoing drainage than in patients who were undergoing drainage. The CSF protein and glucose concentrations, which are diagnostic indicators of meningitis, were positively correlated with the VCM concentration in CSF and the CSF/plasma VCM concentration ratio. Thus, VCM transferability to CSF may be affected by changes in the status of the blood-brain barrier and blood-cerebrospinal fluid barrier due to drainage or meningitis 3).

Indications

Vancomycin Indications.

Vancomycin powder

see Vancomycin powder.

Intraventricular Vancomycin

Intraventricular Vancomycin

1)

Autmizguine J, Moran C, Gonzalez D, Capparelli EV, Smith PB, Grant GA, Benjamin DK Jr, Cohen-Wolkowiez M, Watt KM. Vancomycin cerebrospinal fluid pharmacokinetics in children with cerebral ventricular shunt infections. Pediatr Infect Dis J. 2014 Oct;33(10):e270-2. doi: 10.1097/INF.0000000000000385. PMID: 24776517; PMCID: PMC4209191.
2)

Albanèse J, Léone M, Bruguerolle B, Ayem ML, Lacarelle B, Martin C. Cerebrospinal fluid penetration and pharmacokinetics of vancomycin administered by continuous infusion to mechanically ventilated patients in an intensive care unit. Antimicrob Agents Chemother. 2000 May;44(5):1356-8. doi: 10.1128/AAC.44.5.1356-1358.2000. PMID: 10770777; PMCID: PMC89870.
3)

Ichinose N, Shinoda K, Yoshikawa G, Fukao E, Enoki Y, Taguchi K, Oda T, Tsutsumi K, Matsumoto K. Exploring the Factors Affecting the Transferability of Vancomycin to Cerebrospinal Fluid in Postoperative Neurosurgical Patients with Bacterial Meningitis. Biol Pharm Bull. 2022;45(9):1398-1402. doi: 10.1248/bpb.b22-00361. PMID: 36047211.

Sevoflurane

Sevoflurane (Ultane®)

Mildly increases CBF and ICP, and reduces CMRO2. Mild negative inotrope, cardiac output not as well maintained as with isoflurane or desflurane.

Indications

Sevoflurane is a sweet-smelling, nonflammable, highly fluorinated methyl isopropyl ether used as an inhalational anesthetic for induction and maintenance of general anesthesia. After desflurane, it is the volatile anesthetic with the fastest onset.

The general inhalation anesthetic sevoflurane can be used for the topical treatment of complicated wounds. It is applied in liquid form and may be used to irrigate the inside of cavities. Sevoflurane also exhibits in vitro antimicrobial activity. Therefore, sevoflurane may be used as an alternative to typical antibiotic or surgical treatment of complicated, localized infections.

Prospective preliminary studies

Joys et al. from Chandigarh, used digital subtraction angiography to compare the effects of propofol and sevoflurane on the luminal diameter of cerebral vessels and on cerebral vascular mean transit time in patients with aneurysmal subarachnoid hemorrhage (aSAH).

This prospective preliminary study included adult patients with good-grade aSAH scheduled for endovascular coil embolization; patients were randomized to receive propofol or sevoflurane anesthesia during endovascular coiling. The primary outcome was the luminal diameter of 7 cerebral vessel segments measured on the diseased and nondiseased sides of the brain at 3-time points: awake, postinduction of anesthesia, and post coiling. Cerebral transit time was also measured as a surrogate for cerebral blood flow.

Eighteen patients were included in the analysis (9 per group). Baseline and intraoperative parameters were similar between the groups. Propofol increased the diameter of 1 vessel segment at postinduction and post coiling on the diseased side and in 1 segment at post coiling on the nondiseased side of the brain (P<0.05). Sevoflurane increased vessel diameter in 3 segments at postinduction and in 2 segments at post coiling on the diseased side, and in 4 segments at post coiling on the nondiseased side (P<0.05). Cerebral transit time did not change compared with baseline awake state in either group and was not different between the groups.

Sevoflurane has cerebral vasodilating properties compared with propofol in patients with good-grade aneurysmal subarachnoid hemorrhage (aSAH). However, sevoflurane affects cerebral vascular mean transit time comparably to propofol 1).

Case reports

The case of a 61-year-old male patient who suffered a cranioencephalic trauma 18 years previously is presented. The patient underwent surgeries related to the trauma on numerous occasions. To date, he has suffered various recurrent epidural abscesses, which have been treated with surgical cleaning and antibiotic treatment. In the most recent episode, he presented a frontal epidural abscess 25 mm in diameter with fistulization of the skin. The patient gave written informed consent to be treated with sevoflurane irrigation, and the Pharmacy Service authorized the off-label use. Sevoflurane was applied via a catheter placed inside the cavity during weekly outpatient procedures. The procedures began 8 weeks after the clinically and radiologically verified recovery of the abscess. By avoiding surgery and the associated hospital admission, this novel alternative may prevent patient morbidity and, furthermore, may produce important economic savings.

The treatment of complicated wounds with liquid sevoflurane may be an effective and economically efficient clinical alternative for some patients 2).

1)

Joys S, Panda NB, Ahuja CK, Luthra A, Tripathi M, Mahajan S, Kaloria N, Jain C, Singh N, Regmi S, Jangra K, Chauhan R, Soni SL, Bhagat H. Comparison of Effects of Propofol and Sevoflurane on the Cerebral Vasculature Assessed by Digital Substraction Angiographic Parameters in Patients Treated for Ruptured Cerebral Aneurysm: A Preliminary Study. J Neurosurg Anesthesiol. 2022 Jan 28. doi: 10.1097/ANA.0000000000000833. Epub ahead of print. PMID: 35090162.
2)

Ferrara P, Domingo-Chiva E, Selva-Sevilla C, Campos-García J, Gerónimo-Pardo M. Irrigation with Liquid Sevoflurane and Healing of a Postoperative, Recurrent Epidural Infection: A Potential Cost-Saving Alternative. World Neurosurg. 2016 Jun;90:702.e1-5. doi: 10.1016/j.wneu.2016.02.079. Epub 2016 Feb 24. PubMed PMID: 26924116.

Animal model

Animal model

Is a living, non-human animal used during the research and investigation of human disease, for the purpose of better understanding the disease process without the added risk of harming an actual human. The animal chosen will usually meet a determined taxonomic equivalency to humans, so as to react to disease or its treatment in a way that resembles human physiology as needed. Many drugs, treatments and cures for human diseases have been developed with the use of animal models.

Animal models representing specific taxonomic groups in the research and study of developmental processes are also referred to as model organisms.

There are three main types of animal models: Homologous, Isomorphic and Predictive. Homologous animals have the same causes, symptoms and treatment options as would humans who have the same disease. Isomorphic animals share the same symptoms and treatments, only. Predictive models are similar to a particular human disease in only a couple of aspects. However, these are useful in isolating and making predictions about mechanisms of a set of disease features.

Animal Model for microvascular anastomosis

Animal Model for microvascular anastomosis.

Animal models of spinal injury for studying back pain and SCI

Animal models to understand the back pain mechanism, treatment modalities, and spinal cord injury are widely researched topics worldwide. Despite the presence of several animal models on disc degeneration and Spinal Cord Injury, there is a lack of a comprehensive review.

A methodological narrative literature review was carried out for the study. A total of 1273 publications were found, out of which 763 were related to spine surgery in animals. The literature with full-text availability was selected for the review. Scale for the Assessment of Narrative Review Articles (SANRA) guidelines was used to assess the studies. Only English language publications were included which were listed on PubMed. A total of 113 studies were shortlisted (1976-2019) after internal validation scoring.

The animal models for spine surgery ranged from rodents to primates. These are used to study the mechanisms of back pain as well as spinal cord injuries. The models could either be created surgically or through various means like use of electric cautery, chemicals or trauma. Genetic spine models have also been documented in which the injuries are created by genetic alterations and knock outs. Though the dorsal approach is the most common, the literature also mentions the anterior and lateral approach for spine surgery animal experiments.

There are no single perfect animal models to represent and study human models. The selection is based on the application and the methodology. Careful selection is needed to give optimum and appropriate results 1).

Animal models for central poststroke pain

Dejerine Roussy syndrome or thalamic pain syndrome is a condition developed after a thalamic stroke, a stroke causing damage to the thalamus. Ischemic strokes and hemorrhagic strokes can cause lesioning in the thalamus. The lesions, usually present in one hemisphere of the brain, most often cause an initial lack of sensation and tingling in the opposite side of the body. Weeks to months later, numbness can develop into severe and chronic pain that is not proportional to an environmental stimulus, called dysaesthesia or allodynia. As initial stroke symptoms, numbness and tingling, dissipate, an imbalance in sensation causes these later syndromes, characterizing Dejerine–Roussy syndrome. Although some treatments exist, they are often expensive, chemically based, invasive, and only treat patients for some time before they need more treatment, called “refractory treatment.” Thalamic pain syndrome is a condition developed after a thalamic stroke. Research into its underlying mechanisms and treatment options could benefit from a valid animal model. Nine different animal models have been published, but there are relatively few reports on successful reproductions of these models and so far only little advances in the understanding or the management have been made relying on these models. In general, the construct validity (similarity in underlying mechanisms) of these animal models is relatively high, although this cannot be evaluated into depth because of lack of understanding the mechanisms through which thalamic stroke can lead to thalamic pain syndrome. The face validity (symptom similarity) is relatively low, mainly because pain in these models is tested almost exclusively through evoked mechanical/thermal hypersensitivity assessed by reflexive measures and given the conflicting results with similar tests in patients with thalamic pain syndrome. The predictive validity (similarity in treatment efficacy) has not been evaluated in most models and incorporates difficulties that are specific to thalamic pain syndrome. De Vloo et al., compare the different models regarding these types of validity and discuss the robustness, reproducibility, and problems regarding the design and reporting of the articles establishing these models. They conclude with various proposals on how to improve the validity and reproducibility of thalamic pain syndrome animal models. Until further improvements are achieved, prudence is called for in interpreting results obtained through these models 2).

Animal model for multiple sclerosis

Kalkowski et al. combined the advantages of the demyelination model with experimental autoimmune encephalomyelitis (EAE) to provide a local autoimmune encephalomyelitis (LAE) inside the rat brain. They induced a demyelinating lesion by immunizing male Wistar rats, followed by blood-brain barrier opening protein (vascular endothelial growth factor) by stereotactic injection. They confirmed the immunization against myelin epitopes and minor neurological impairment. The histological assessment confirmed the lesion development after both 3- and 7 days post-injection. This approach was sufficient to develop a demyelinating lesion with high reproducibility and low morbidity 3).

Books

Experimental Neurosurgery in Animal Models (Neuromethods) From Humana Press

This volume provides a full explanation and technical details to perform surgical techniques properly on small and large animal models. The first six chapters of Experimental Neurosurgery in Animal Models focus primarily on the brain, while the next six chapters concern the spinal cord in rodents. The last four chapters provide a description of operative procedures in large animals. Written for the popular Neuromethods series, chapters include the kind of detail and key implementation advice that ensures successful results in the laboratory.

Authoritative and practical, Experimental Neurosurgery in Animal Models aims to ensure successful results in the further study of this vital field.

Murine model

Murine model

1)

Goel SA, Varghese V, Demir T. Animal models of spinal injury for studying back pain and SCI. J Clin Orthop Trauma. 2020;11(5):816-821. doi:10.1016/j.jcot.2020.07.004
2)

De Vloo P, Morlion B, van Loon J, Nuttin B. Animal models for central poststroke pain: a critical comprehensive review. Pain. 2017 Jan;158(1):17-29. PubMed PMID: 27992392.
3)

Kalkowski L, Golubczyk D, Kwiatkowska J, Domzalska M, Walczak P, Malysz-Cymborska I. Local autoimmune encephalomyelitis model in a rat brain with precise control over lesion placement. PLoS One. 2022 Jan 21;17(1):e0262677. doi: 10.1371/journal.pone.0262677. PMID: 35061807.