Today: Neurosurgical Approaches to the Cranial Compartments

Neurosurgical Approaches to the Cranial Compartments

This course is aimed at ST3-ST8 level trainees and subspecialty (skull base and cerebrovascular) fellows. Teaching of the approaches are tailored to the specific needs and experience of the individual trainee. This workshop is co-organised by the east and west of Scotland training programs. The program includes complex surgical procedures which cannot be performed by trainees without prior cadaveric exposure.

It covers the whole armamentarium of intracranial approaches and provides fundamental insight to very complex procedures. The focus is on enabling trainees to safely approach superficial and deep seated vascular and benign intracranial lesions arising from or being in proximity to the cranial vault or skull base. Trainees will gain a heightened appreciation of the critical structures encountered through these approaches.

Suitability

ST3-ST8 and subspecialty (skull base and cerebrovascular) fellows. Teaching of the approaches will be tailored to the specific needs and experience of the individual trainee.

Relevant Grades: ST3, ST4, ST5, ST6, ST7, ST8, SpR, SAS

Course Format

Introductory Lectures followed by hands on Cadaveric workshops. Commonly performed techniques such as pterional, bifrontal, middle fossa and retrosigmoid craniotomies will be covered as well as more complex approaches to the third ventricle, pineal region, antero-lateral brainstem and C1/C2 complex. State of the art Pentero Zeiss microscopes, Integra Mayfield clamps, Codman microinstruments, and Anspach high speed drills will be readily available in all stations (two participants per station – one faculty member per station)

Course Objectives

Familiarize trainees with the surgical anatomy pertinent to common as well as complex neurosurgical procedures, which will be comprehensively taught. Identify anatomical avenues for the safe exposure of both superficial and deeper intracranial structures. Expose trainees to microsurgical principles (appropriate application of the operating microscope, high speed drill, and microdissection).

Learning Outcomes

Upon completion of the course, participants should be able to:

  • Enable trainees to safely approach superficial and deep seated vascular and benign intracranial lesions arising from or being in proximity to the cranial vault or skull base.
  • Trainees will have a heightened appreciation of the critical structures encountered through these approaches.

Unplanned hospital readmission after cranial neurosurgery

Unplanned hospital readmission after cranial neurosurgery

Many readmissions may be preventable and occur at predictable time intervals. The causes and timing of readmission vary significantly across neurosurgical subgroups. Future studies should focus on detecting specific complications in select cohorts at predefined time points, which may allow for interventions to lower costs and reduce patient morbidity 1).


Hospital readmission to a hospital (non-index) other than the one from which patients received their original care (index) has been associated with increases in both morbidity and mortality for cancer patients.

Of patient readmissions following brain tumor resection, 15.6% occur at a non-index facility. Low procedure volume is a confounder for non-index analysis and is associated with an increased likelihood of major complications and mortality, as compared to readmission to high-procedure-volume hospitals. Further studies should evaluate interventions targeting factors associated with unplanned readmission 2).


In a single-center Canadian experience. Almost one-fifth of neurosurgical patients were readmitted within 30 days of discharge. However, only about half of these patients were admitted for an unplanned reason, and only 10% of all readmissions were potentially avoidable. This study demonstrates unique challenges encountered in a publicly funded healthcare setting and supports the growing literature suggesting 30-day readmission rates may serve as an inappropriate quality of care metric in neurosurgical patients. Potentially avoidable readmissions can be predicted, and further research assessing predictors of avoidable readmissions is warranted 3).

A study of Elsamadicy et al. suggested that infection, altered mental status, and new sensory/motor deficits were the primary complications leading to unplanned 30-day readmission after cranial neurosurgery 4).


The preponderance of postdischarge mortality and complications requiring readmission highlights the importance of posthospitalization management 5).


Obstructive sleep apnea (OSA) is known to be associated with negative outcomes and is underdiagnosed. The STOP-Bang questionnaire is a screening tool for OSA that has been validated in both medical and surgical populations. Given that readmission, after surgical intervention is an undesirable event, Caplan et al. sought to investigate, among patients not previously diagnosed with OSA, the capacity of the STOP-Bang questionnaire to predict 30-day readmissions following craniotomy for a supratentorial tumor.

For patients undergoing craniotomy for treatment of a supratentorial neoplasm within a multiple-hospital academic medical center, data were captured in a prospective manner via the Neurosurgery Quality Improvement Initiative (NQII) EpiLog tool. Data were collected over a 1-year period for all supratentorial craniotomy cases. An additional criterion for study inclusion was that the patient was alive at 30 postoperative days. Statistical analysis consisted of simple logistic regression, which assessed the ability of the STOP-Bang questionnaire and additional variables to effectively predict outcomes such as 30-day readmission, 30-day emergency department (ED) visit, and 30-day reoperation. The C-statistic was used to represent the receiver operating characteristic (ROC) curve, which analyzes the discrimination of a variable or model.

Included in the sample were all admissions for supratentorial neoplasms treated with craniotomy (352 patients), 49.72% (n = 175) of which were female. The average STOP-Bang score was 1.91 ± 1.22 (range 0-7). A 1-unit higher STOP-Bang score accurately predicted 30-day readmissions (OR 1.31, p = 0.017) and 30-day ED visits (OR 1.36, p = 0.016) with fair accuracy as confirmed by the ROC curve (C-statistic 0.60-0.61). The STOP-Bang questionnaire did not correlate with 30-day reoperation (p = 0.805) or home discharge (p = 0.315).

The results of this study suggest that undiagnosed OSA, as assessed via the STOP-Bang questionnaire, is a significant predictor of patient health status and readmission risk in the brain tumor craniotomy population. Further investigations should be undertaken to apply this prediction tool in order to enhance postoperative patient care to reduce the need for unplanned readmissions 6).


Lopez Ramos et al., from the Department of Neurological Surgery, University of California San Diego, La Jolla, CA, USA, examined clinical risk factors and postoperative complications associated with 30-day unplanned hospital readmissions after cranial neurosurgery.

They queried the American College of Surgeons National Surgical Quality Improvement Program database from 2011-2016 for adult patients that underwent a cranial neurosurgical procedure. Multivariable logistic regression with backwards model selection was used to determine predictors associated with 30-day unplanned hospital readmission.

Of 40,802 cranial neurosurgical cases, 4,147 (10.2%) had an unplanned readmission. Postoperative complications were higher in the readmission cohort (18.5% vs 9.9%, p <0.001). On adjusted analysis, clinical factors predictive of unplanned readmission included hypertension, COPD, diabetes, coagulopathy, chronic steroid use, and preoperative anemia, hyponatremia, and hypoalbuminemia (all p ≤ 0.01). Higher ASA class (III-V), operative time >216 minutes, and unplanned reoperation were also associated with an increased likelihood of readmission (all p ≤0.001). Postoperative complications predictive of unplanned readmissions were wound infection (OR 4.90, p <0.001), pulmonary embolus (OR 3.94, p <0.001), myocardial infarction/cardiac arrest (OR 2.37, p <0.001), sepsis (OR 1.73, p <0.001), deep venous thrombosis (1.50, p=0.002), and urinary tract infection (OR 1.45, p=0.002). Female sex, transfer status, and postoperative pulmonary complications were protective of readmission (all p <0.05)

Unplanned hospital readmission after cranial neurosurgery is a common event. Identification of high-risk patients who undergo cranial procedures may allow hospitals to reduce unplanned readmissions and associated healthcare costs 7).


Cusimano et al., conducted a systematic review of several databases; a manual search of the Journal of NeurosurgeryNeurosurgeryActa NeurochirurgicaCanadian Journal of Neurological Sciences; and the cited references of the selected articles. Quality review was performed using the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) criteria. Findings are reported according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.

A total of 1344 articles published between 1947 and 2015 were identified; 25 were considered potentially eligible, of which 12 met inclusion criteria. The 30-day readmission rates varied from 6.9% to 23.89%. Complications arising during or after neurosurgical procedures were a prime reason for readmission. Race, comorbidities, and longer hospital stay put patients at risk for readmission.

Although readmission may be an important indicator for good care for the subset of acutely declining patients, neurosurgery should aim to reduce 30-day readmission rates with improved quality of care through systemic changes in the care of neurosurgical patients that promote preventive measures 8).

References

1)

Taylor BE, Youngerman BE, Goldstein H, Kabat DH, Appelboom G, Gold WE, Connolly ES Jr. Causes and Timing of Unplanned Early Readmission After Neurosurgery. Neurosurgery. 2016 Sep;79(3):356-69. doi: 10.1227/NEU.0000000000001110. PubMed PMID: 26562821.
2)

Jarvis CA, Bakhsheshian J, Ding L, Wen T, Tang AM, Yuan E, Giannotta SL, Mack WJ, Attenello FJ. Increased complication and mortality among non-index hospital readmissions after brain tumor resection is associated with low-volume readmitting hospitals. J Neurosurg. 2019 Oct 4:1-13. doi: 10.3171/2019.6.JNS183469. [Epub ahead of print] PubMed PMID: 31585421.
3)

Wilson MP, Jack AS, Nataraj A, Chow M. Thirty-day readmission rate as a surrogate marker for quality of care in neurosurgical patients: a single-center Canadian experience. J Neurosurg. 2018 Jul 1:1-7. doi: 10.3171/2018.2.JNS172962. [Epub ahead of print] PubMed PMID: 29979117.
4)

Elsamadicy AA, Sergesketter A, Adogwa O, Ongele M, Gottfried ON. Complications and 30-Day readmission rates after craniotomy/craniectomy: A single Institutional study of 243 consecutive patients. J Clin Neurosci. 2018 Jan;47:178-182. doi: 10.1016/j.jocn.2017.09.021. Epub 2017 Oct 12. PubMed PMID: 29031542.
5)

Dasenbrock HH, Yan SC, Smith TR, Valdes PA, Gormley WB, Claus EB, Dunn IF. Readmission After Craniotomy for Tumor: A National Surgical Quality Improvement Program Analysis. Neurosurgery. 2017 Apr 1;80(4):551-562. doi: 10.1093/neuros/nyw062. PubMed PMID: 28362921.
6)

Caplan IF, Glauser G, Goodrich S, Chen HI, Lucas TH, Lee JYK, McClintock SD, Malhotra NR. Undiagnosed obstructive sleep apnea as a predictor of 30-day readmission for brain tumor patients. J Neurosurg. 2019 Jul 19:1-6. doi: 10.3171/2019.4.JNS1968. [Epub ahead of print] PubMed PMID: 31323636.
7)

Lopez Ramos C, Brandel MG, Rennert RC, Wali AR, Steinberg JA, Santiago-Dieppa DR, Burton BN, Pannell JS, Olson SE, Khalessi AA. Clinical Risk Factors and Postoperative Complications Associated with Unplanned Hospital Readmissions After Cranial Neurosurgery. World Neurosurg. 2018 Jul 24. pii: S1878-8750(18)31614-0. doi: 10.1016/j.wneu.2018.07.136. [Epub ahead of print] PubMed PMID: 30053566.
8)

Cusimano MD, Pshonyak I, Lee MY, Ilie G. A systematic review of 30-day readmission after cranial neurosurgery. J Neurosurg. 2017 Aug;127(2):342-352. doi: 10.3171/2016.7.JNS152226. Epub 2016 Oct 21. PubMed PMID: 27767396.

Cranial nerve tractography

Cranial nerve tractography

Diffusion imaging tractography caught the attention of the scientific community by describing the white matter architecture in vivo and noninvasively, but its application to small structures such as cranial nerves remains difficult. The few attempts to track cranial nerves presented highly variable acquisition and tracking settings.

A “targeted” review of the scientific literaturewas carried out using the MEDLINEdatabase.

Jacquesson et al., selected studies that reported how to perform the tractography of cranial nerves, and extracted the following: clinical context; imaging acquisition settings; tractography parameters; regions of interest (ROIs) design; and filtering methods.

Twenty-one published articles were included. These studied the optic nerves in suprasellar tumors, the trigeminal nerve in neurovascular conflicts, the facial nerve position around vestibular schwannomas, or all cranial nerves. Over time, the number of MRI diffusion gradient directions increased from 6 to 101. Nine tracking software packages were used which offered various types of tridimensional display. Tracking parameters were disparately detailed except for fractional anisotropy, which ranged from 0.06 to 0.5, and curvature angle, which was set between 20° and 90°. ROI design has evolved towards a multi-ROI strategy. Furthermore, new algorithms are being developed to avoid spurious tracts and improve angular resolution.

This review highlights the variability in the settings used for cranial nerve tractography. It points out challenges that originate both from cranial nerve anatomy and the tractography technology, and allows a better understanding of cranial nerve tractography 1).

Case series

Five neurologically healthy adults and 3 patients with brain tumors were scanned with diffusion spectrum imaging that allowed high-angular-resolution fiber tracking. In addition, a 488-subject diffusion magnetic resonance imaging template constructed from the Human Connectome Project data was used to conduct atlas space fiber tracking of CNs.

The cisternal portions of most CNs were tracked and visualized in each healthy subject and in atlas fiber tracking. The entire optic radiation, medial longitudinal fasciculus, spinal trigeminal nucleus/tract, petroclival portion of the abducens nerve, and intrabrainstem portion of the facial nerve from the root exit zone to the adjacent abducens nucleus were identified. This suggested that the high-angular-resolution fiber tracking was able to distinguish the facial nerve from the vestibulocochlear nerve complex. The tractography clearly visualized CNs displaced by brain tumors. These tractography findings were confirmed intraoperatively.

Using high-angular-resolution fiber tracking and atlas-based fiber tracking, we were able to identify all CNs in unprecedented detail. This implies its potential in localization of CNs during surgical planning 2).

Videos

Visualization of Cranial Nerves Using High-Definition Fiber Tractography

References

1)

Jacquesson T, Frindel C, Kocevar G, Berhouma M, Jouanneau E, Attyé A, Cotton F. Overcoming Challenges of Cranial Nerve Tractography: A Targeted Review. Neurosurgery. 2019 Feb 1;84(2):313-325. doi: 10.1093/neuros/nyy229. PubMed PMID: 30010992.
2)

Yoshino M, Abhinav K, Yeh FC, Panesar S, Fernandes D, Pathak S, Gardner PA, Fernandez-Miranda JC. Visualization of Cranial Nerves Using High-Definition Fiber Tractography. Neurosurgery. 2016 Jul;79(1):146-65. doi: 10.1227/NEU.0000000000001241. PubMed PMID: 27070917.
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