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Right brain? Hemispheric dominance and the United States presidency

Nathan R. Selden

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Mentorship: service, education, progress. The 2015 CNS Presidential Address

Nathan R. Selden

The theme of the 65th Annual Meeting of the Congress of Neurological Surgeons and the title of this presidential address focus on mentorship as a valuable service owed to the profession of neurological surgery by its members, a crucial tool for the education of new neurosurgeons, and a fundamental contributor to the progress of the specialty. The author explores the origin of the term “mentor” in Homeric tradition and the impact of mentorship on the historical legacy of neurological surgery. He outlines the role mentorship played in his own professional development, as well as the changing face of mentorship today due to increasing numbers of women in neurosurgery.

Many surgeons perceive modern educational approaches as threats to the tradition of personal mentorship in medicine. The author argues that intentional educational methods, such as the Society of Neurological Surgeons (SNS) “matrix” curriculum, the Accreditation Council for Graduate Medical Education “milestones,” and the SNS “boot camp” courses, each focus, enhance, and empower, but do not replace, personal mentorship. The author further describes the important role of mentorship in the definition, growth, and health of the specialty of neurological surgery and in the personal well-being and fulfillment of its practitioners.

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Minimal tethered cord syndrome: what's necessary to justify a new surgical indication?

Nathan R. Selden

✓Traditionally, surgical division of the terminal filum (filum terminale) has been reserved for patients with imaging-apparent spinal cord tethering. The occurrence of medically refractory voiding dysfunction of neurogenic origin, without magnetic resonance (MR) imaging documentation of abnormality in the spine, has been termed “minimal” tethered cord syndrome (TCS). The rationale for and utility of using surgical division of the terminal filum in the treatment of minimal TCS are unproven.

Six studies that involved surgical division of the terminal filum for minimal TCS were identified and reviewed. A seventh study conducted prior to the MR imaging era, in which authors used myelography, was also included. In addition, two investigations of the clinicopathological findings in such cases were analyzed. A tripartite criterion for justifying the introduction of a new surgical indication is proposed and analyzed in light of this evidence.

In children with minimal TCS there are definite pathological changes in the terminal filum that are not visible on routine spinal MR imaging. These changes suggest that the pathophysiology of minimal TCS, like TCS that is demonstrated on neuroimaging, may involve abnormal traction on the distal spinal cord. Additional data are needed regarding the sensitivity and specificity of various clinical studies intended to identify children with minimal TCS. All existing data supporting the efficacy of surgery for minimal TCS have been generated by Class III studies. Clinical equipoise exists for this surgical indication, and, therefore, a prospective randomized trial should be completed.

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Stem cells and central nervous system therapeutics

Nathan R. Selden

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Occult tethered cord syndrome: the case for surgery

Nathan R. Selden

Object

Controversy exists regarding proper indications for surgical lysis of the terminal filum in children with voiding dysfunction and tethered spinal cord. Recently, surgery has been offered to children who have a normally positioned conus medullaris and no terminal filum abnormality visible on 1.5-tesla magnetic resonance images (referred to as minimal or occult tethered cord syndrome [TCS]). The author evaluates existing clinical and scientific evidence relevant to this controversy.

Methods

Five retrospective, observational, noncontrolled studies of surgical terminal filum lysis for occult TCS in children were identified. Two further studies in which the authors reported surgical results in children with a normal-level conus medullaris were also identified.

Conclusions

These studies document encouraging clinical outcomes following surgery. Clinicopathological evidence suggests that occult TCS may result from radiographically occult structural abnormalities of the terminal filum. Although a preponderance of Class III clinical evidence supports the use of surgical filum lysis to treat occult TCS, no Class I or II evidence exists. Clinical practice varies; therefore, performance of a prospective randomized clinical trial of surgical terminal filum lysis for the treatment of occult TCS is advocated.

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Dura-splitting decompression of the craniocervical junction: reduced operative time, hospital stay, and cost with equivalent early outcome

Farhad M. Limonadi and Nathan R. Selden

Object. The choice of surgical technique for decompressive surgery in patients with Chiari I malformation is controversial. Good preliminary postoperative outcomes have been achieved in patients with Chiari I malformation (without syringomyelia) after using a dura-splitting technique. The authors evaluated safety, resource use, and early outcome after this surgery in patients without syringomyelia and compared the findings associated with duraplasty in patients with syringomyelia.

Methods. A prospective series of 24 patients with Chiari I malformation (12 with a syrinx) underwent decompression of the craniocervical junction (CCJ). An allograft-augmented duraplasty was performed in patients with syringomyelia. Intraoperative ultrasonography confirmed adequate tonsillar decompression after lysis of the periosteal bands at the foramen magnum and C-1 arch as well as partial resection of the outer leaf of the dura in patients without syringomyelia. Patients in each group were of similar mean age (syringomyelia 10.8 years and no syringomyelia 7.6 years old; p = 0.07) and functional status. The mean follow-up period was 15.3 months (range 3–30 months). Dura-splitting decompression required significantly less mean operative time (99 minutes compared with 169 minutes, respectively; p < 0.001), total operating room time (166 minutes compared with 249 minutes, respectively; p < 0.001), duration of hospitalization (3 days compared with 3.75 days, respectively; p < 0.05), perioperative charges ($3615 compared with $5538, respectively; p < 0.001), and overall hospital charges ($7705 compared with $9759, respectively; p < 0.001) than the duraplasty. Mean clinical outcome scores were similar (syringomyelia 1.53 of 2; no syringomyelia 1.67 of 2; not statistically significant).

Conclusions. Dura-splitting CCJ decompression in pediatric patients with Chiari I malformation and without syringomyelia is safe, provides good early clinical results, and significantly reduces resource use. A randomized controlled trial of dura-splitting decompression in a uniform population of patients with Chiari I malformation is indicated.

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Pullout-proofing external ventricular drains

Technical note

Nathaniel L. Whitney and Nathan R. Selden

Object

The authors describe a method of securing an external ventricular drain (EVD) to prevent dislodgement and discourage CSF leakage and infection.

Methods

The EVD is secured using a single permanent suture, creating a box stitch around the exit site attached to a modified roman sandal. Multiple knots are tied after each loop to avoid “telescoping,” loosening, and pullout.

Results

In 12 years of high-volume pediatric practice by one of the authors, only one drain has broken, and none have pulled out.

Conclusions

The modified roman sandal technique tightly secures EVDs against pullout. Anecdotal evidence suggests that the strength of the suture construct securing the drain is greater than that of the drain tubing itself.

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Technical challenges to anterior temporal lobectomy after laser interstitial thermal therapy for mesial temporal lobe epilepsy: technical note

Molly E. Hubbard, Nasser K. Yaghi, and Nathan R. Selden

Mesial temporal sclerosis (MTS) is a frequent cause of medically refractory epilepsy, for which laser interstitial thermal therapy (LITT) is an effective treatment. However, experience with the technical considerations posed by additional surgery after an initial LITT procedure is lacking. The authors present the case of a 12-year-old female with medically refractory temporal lobe epilepsy and left MTS who underwent LITT at a separate institution prior to referral. This patient had no change in early postoperative seizure control (Engel class IVB) and then her seizures worsened despite ongoing medical treatment (Engel class IVC). Post-LITT MRI revealed sparing of the mesial hippocampus head, a poor prognostic factor. The authors describe the technical details illustrated by this case of secondary, stereotactic electroencephalography–guided mesial temporal resection following LITT. The case was managed with anterior temporal lobectomy including the resection of residual hippocampus and amygdala.

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Utility of serial computed tomography imaging in pediatric patients with head trauma

Susan R. Durham, Kenneth C. Liu, and Nathan R. Selden

Object

The purpose of this study was to evaluate the risk of progression of traumatic intracranial lesions in children by comparing initial and subsequent computed tomography (CT) scans. Reserving repeated CT imaging for patients who harbor higher-risk lesions may reduce overall radiation exposure, the need for sedative agents, and cost.

Methods

The authors performed a retrospective cohort study in 268 patients younger than 18 years of age who underwent repeated CT scanning within 24 hours of their initial CT scanning procedure. The risk of progression between the initial and repeated CT scanning sessions and the need for delayed neurosurgical intervention were determined for each lesion type.

In 54 patients (20.1%) the normal findings on the initial CT study did not change on subsequent imaging. In 61 (28.5%) of the 214 patients in whom abnormal findings were present on the initial scan, progression was demonstrated. Patients with epidural hematoma (EDH; odds ratio [OR] 12.29), subdural hematoma (SDH; OR 3.18), cerebral edema (OR 9.34), and intraparenchymal hemorrhage (IPH; OR 18.3) were found to be at a significantly increased risk for progression and to require delayed neurosurgical intervention (OR 11.91). No significantly increased risk was found for patients with subarachnoid hemorrhage (SAH), intraventricular hemorrhage (IVH), diffuse axonal injury (DAI), or skull fracture.

Conclusions

Repeated CT imaging in children with high-risk lesions such as EDH, SDH, cerebral edema, and IPH is recommended. However, in children with low-risk lesions, such as SAH, IVH, DAI, and isolated skull fractures but no sign of clinical deterioration, repeated imaging may be less likely to alter the clinical management scheme. The limited benefits of undertaking repeated imaging in these patients should be weighed against the risks of radiation exposure, sedation, intrahospital transportation, and patient monitoring.

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Results of a North American survey of rapid-sequence MRI utilization to evaluate cerebral ventricles in children

Clinical article

Eric M. Thompson, Lissa C. Baird, and Nathan R. Selden

Object

Growing concern about potential adverse effects of ionizing radiation exposure during imaging studies is particularly relevant to the pediatric population. To decrease radiation exposure, many institutions use rapid-sequence (or quick-brain) MRI to evaluate cerebral ventricle size. There are obstacles, however, to widespread implementation of this imaging modality. The purpose of this study was to define and quantify these obstacles to positively affect institutional and governmental policy.

Methods

A 9-question survey was emailed to pediatric neurosurgeons who were either members or candidate members of the American Society of Pediatric Neurosurgeons at every one of 101 institutions in the US and Canada having such a neurosurgeon on staff. Responses were compiled and descriptive statistics were performed.

Results

Fifty-six institutions completed the survey. Forty-four (79%) of the 56 institutions currently have a rapid-sequence MRI protocol to evaluate ventricle size, while 36 (64%) use it routinely. Of the 44 institutions with a rapid-sequence MRI protocol, 29 (66%) have had a rapid-sequence MRI protocol for less than 5 years while 39 (89%) have had a rapid-sequence MRI protocol for no more than 10 years. Thirty-six (88%) of 41 rapid-sequence MRI users responding to this question obtain a T2-weighted rapid-sequence MRI while 13 (32%) obtain a T1-weighted rapid-sequence MRI. Twenty-eight (64%) of 44 institutions never use sedation while an additional 12 (27%) rarely use sedation to obtain a rapid-sequence MRI (less than 5% of studies). Of the institutions with an established rapid-sequence MRI protocol, obstacles to routine use include lack of emergency access to MRI facilities in 18 (41%), lack of staffing of MRI facilities in 12 (27%), and the inability to reimburse a rapid-sequence MRI protocol in 6 (14%). In the 12 institutions without rapid-sequence MRI, obstacles to implementation include lack of emergency access to MRI facilities in 8 (67%), lack of staffing of MRI facilities in 7 (58%), the inability to reimburse in 3 (25%), and lack of administrative support in 3 (25%). To evaluate pediatric head trauma, 53 (96%) of 55 institutions responding to this question use noncontrast CT, no institution uses rapid-sequence MRI, and only 2 (4%) use standard MRI.

Conclusions

Many North American institutions have a rapid-sequence MRI protocol to evaluate ventricle size, with most developing this technique within the past 5 years. Most institutions never use sedation, and most obtain T2-weighted sequences. The greatest obstacles to the routine use of rapid-sequence MRI in institutions with and in those without a rapid-sequence MRI protocol are the lack of emergency access and staffing of the MRI facility during nights and weekends.