Axial MR Angiography in Evaluating Revascularization after Indirect Bypass Surgery for Moyamoya

INTRODUCTION

At our institution, revascularization after indirect moyamoya surgery is routinely evaluated using magnetic resonance angiography (MRA) rather than catheter angiography. This study reviews how revascularization can be visualized on axial MRA versus catheter angiography and compares clinical outcomes of surgeries evaluated by routine postoperative MRA versus routine catheter angiography.

METHODS

We reviewed the records of all patients treated at our institution who underwent unilateral encephaloduroarteriosynangiosis (EDAS)/pial synangiosis 2004-2021 at 1-21 years of age. Inclusion criteria included undergoing preoperative MRA within 18 months of surgery and postoperative MRA 3 to 30 months after surgery. Clinical outcome measures included postoperative stroke and transient ischemic attacks (TIAs), changes in symptoms (improved, unchanged, worsened), and new postoperative symptoms. Measures were compared between surgeries evaluated by routine postoperative MRA versus routine postoperative angiograms. For each surgery, we determined the ratios of the diameters and areas of the donor and contralateral corresponding vessels and the relative signal intensities of these two vessels on preoperative- and 3-to-30-month postoperative MRA. We did the same for the middle meningeal artery (MMA) ipsilateral to the donor artery and the contralateral MMA. We assessed changes from pre- to post-operation in diameter ratios, area ratios, relative signal intensity, ivy sign, and brain perfusion on arterial spin labeled (ASL) imaging. MRI and MRA measures of revascularization and flow were compared to Matsushima grades in patients who had postoperative catheter angiograms.

RESULTS

Fifty-one operations were included. There were no significant differences in rates of strokes, TIAs, changes or new symptoms after surgeries evaluated by routine postoperative MRA versus catheter angiogram. Significant associations existed between greater collateralization on postoperative MRA and greater median increases in preoperative-to-postoperative ratios of donor-vessel-over-contralateral-vessel diameter (p=0.0461) and ipsilateral-MMA-over-contralateral-MMA diameter (p=0.0135). The median increase in the ratio of the donor-vessel-over-corresponding-contralateral-vessel diameters was significantly higher for Matsushima grade A versus B (p=0.036). The median increase in the ratio of the sum of donor-and-ipsilateral-MMA diameters over the sum of the contralateral vessel diameters was significantly higher for improved-versus-unchanged perfusion on ASL imaging (p=0.0074). There was a nonsignificant association between greater postoperative collateralization on MRA and Matsushima grade (p=0.1160) Conclusion: Cerebral revascularization after EDAS/pial synangiosis can be evaluated on axial MRA by comparing the diameter and/or signal intensity of the donor vessel and ipsilateral MMA to those of the corresponding contralateral vessels on postoperative-versus-preoperative MRA. The use of routine postoperative MRA rather than catheter angiography does not appear to negatively affect outcomes.

Pediatric pineal region masses: a single-center experience over 25 years

PURPOSE

Pineal region tumors (PRT) represent less than 1% of brain neoplasms. The rare and heterogeneous nature of these tumors is reflected in the variety of treatment modalities employed.

METHODS

A single-center retrospective review of all pediatric patients with pineal region tumors between November 1996 and June 2021 was performed. Fifty-six cases of pineal tumors were reviewed for age and symptoms upon presentation, diagnostic methods, imaging characteristics, histological classification, treatment modalities, recurrence, and mortality rates.

RESULTS

The average age at diagnosis was 11.3 years. The majority of patients were male (82.1%) and Caucasian (73.2%). The most common presenting symptoms were headache (n = 38, 67.9%) and visual problems (n = 34, 60.7%). Hydrocephalus was present in 49 patients (87.5%). Germinoma (n = 20, 35.7%) and non-germinomatous germ cell tumor (NGGCT) (n = 17, 30.4%) were the most common tumors. Chemotherapy was employed for 54 patients (96.4%), radiation for 49 (87.5%), and surgical resection for 14 (25.0%). The average duration of treatment was 5.9 months. Progression-free survival was 74.4% at 5 years and 72.0% at 10 years. Overall survival was 85.7% at 5 years and 77.1% at 10 years.

CONCLUSION

Treatment of pineal region tumors must be targeted to each patient based on presentation, subtype, presence of hydrocephalus, and extent of disease. Upfront surgical resection is usually not indicated. As advances in oncological care proceed, treatment modalities may continue to improve in efficacy.

Magnetic resonance imaging-guided stereotactic laser ablation therapy for the treatment of pediatric epilepsy: a retrospective multiinstitutional study

OBJECTIVE

The authors of this study evaluated the safety and efficacy of stereotactic laser ablation (SLA) for the treatment of drug-resistant epilepsy (DRE) in children.

METHODS

Seventeen North American centers were enrolled in the study. Data for pediatric patients with DRE who had been treated with SLA between 2008 and 2018 were retrospectively reviewed.

RESULTS

A total of 225 patients, mean age 12.8 ± 5.8 years, were identified. Target-of-interest (TOI) locations included extratemporal (44.4%), temporal neocortical (8.4%), mesiotemporal (23.1%), hypothalamic (14.2%), and callosal (9.8%). Visualase and NeuroBlate SLA systems were used in 199 and 26 cases, respectively. Procedure goals included ablation (149 cases), disconnection (63), or both (13). The mean follow-up was 27 ± 20.4 months. Improvement in targeted seizure type (TST) was seen in 179 (84.0%) patients. Engel classification was reported for 167 (74.2%) patients; excluding the palliative cases, 74 (49.7%), 35 (23.5%), 10 (6.7%), and 30 (20.1%) patients had Engel class I, II, III, and IV outcomes, respectively. For patients with a follow-up ≥ 12 months, 25 (51.0%), 18 (36.7%), 3 (6.1%), and 3 (6.1%) had Engel class I, II, III, and IV outcomes, respectively. Patients with a history of pre-SLA surgery related to the TOI, a pathology of malformation of cortical development, and 2+ trajectories per TOI were more likely to experience no improvement in seizure frequency and/or to have an unfavorable outcome. A greater number of smaller thermal lesions was associated with greater improvement in TST. Thirty (13.3%) patients experienced 51 short-term complications including malpositioned catheter (3 cases), intracranial hemorrhage (2), transient neurological deficit (19), permanent neurological deficit (3), symptomatic perilesional edema (6), hydrocephalus (1), CSF leakage (1), wound infection (2), unplanned ICU stay (5), and unplanned 30-day readmission (9). The relative incidence of complications was higher in the hypothalamic target location. Target volume, number of laser trajectories, number or size of thermal lesions, or use of perioperative steroids did not have a significant effect on short-term complications.

CONCLUSIONS

SLA appears to be an effective and well-tolerated treatment option for children with DRE. Large-volume prospective studies are needed to better understand the indications for treatment and demonstrate the long-term efficacy of SLA in this population.

Use of the Posterior Auricular Artery for Indirect Bypass in Moyamoya: A Pediatric Case Series

INTRODUCTION

Encephaloduroarteriosynangiosis (EDAS) for moyamoya is predominantly performed using a branch of the superficial temporal artery (STA) as the donor artery. At times, other branches of the external carotid artery (ECA) are better suited for EDAS than is the STA. There is little information in the literature concerning using the posterior auricular artery (PAA) for EDAS in the pediatric age group. In this case series, we review our experience using the PAA for EDAS in children and adolescents.

CASE PRESENTATIONS

We describe the presentations, imaging, and outcomes of three patients in whom the PAA was used for EDAS, as well our surgical technique. There were no complications. All three patients were confirmed to have radiologic revascularization from their surgeries. All patients also had improvement of their preoperative symptoms, and no patient has had a stroke postoperatively.

CONCLUSION

The PAA is a viable option for use as a donor artery in EDAS for the treatment of moyamoya in children and adolescents.

Postoperative general medical ward admission following Chiari malformation decompression

OBJECTIVE

Prior to 2019, the majority of patients at Children's Hospital Colorado were admitted to the pediatric intensive care unit (PICU) following Chiari malformation (CM) decompression surgery. This study sought to identify the safety and efficacy of postoperative general ward management for these patients.

METHODS

After a retrospective baseline assessment of 150 patients, a quality improvement (QI) initiative was implemented, admitting medically noncomplex patients to the general ward postoperatively following CM decompression. Twenty-one medically noncomplex patients were treated during the QI intervention period. All patients were assessed for length of stay, narcotic use, time to ambulation, and postoperative complications.

RESULTS

PICU admission rates postoperatively decreased from 92.6% to 9.5% after implementation of the QI initiative. The average hospital length of stay decreased from 3.4 to 2.6 days, total doses of narcotic administration decreased from 12.3 to 8.7, and time to ambulation decreased from 1.8 to 0.9 days. There were no major postoperative complications identified that were unsuitable for management on a conventional pediatric medical/surgical nursing unit.

CONCLUSIONS

Medically noncomplex patients were safely admitted to the general ward postoperatively at Children's Hospital Colorado after decompression of CM. This approach afforded decreased length of stay, decreased narcotic use, and decreased time to ambulation, with no major postoperative complications.

Spinal cord tethering after selective dorsal rhizotomy below the conus medullaris

BACKGROUND

Two techniques for selective dorsal rhizotomy (SDR) involve stimulating and sectioning nerve rootlets either below the conus medullaris or above the entrances to their respective dural root sleeves. In general, both techniques lead to sustained improvements in lower extremity spasticity with low complication rates. To our knowledge, spinal cord tethering has not been previously reported as a complication of SDR using either technique.

METHODS

We review the presentation, treatment, and outcome of two patients who developed symptomatic spinal cord tethering after SDR below the conus.

RESULTS

A 4-year-old male and a 6-year-old female each with a history of spastic diparetic cerebral palsy underwent L1-L2 osteoplastic laminectomy and SDR below the conus. Both surgeries went well with no known complications. Both patients initially did well, with marked improvement in their tone and gait. There were no significant immediate postoperative bowel or bladder problems. The male patient presented 10 months after surgery with new-onset urinary incontinence. A urological evaluation was performed but no imaging was performed. He re-presented 8 months later with worsened urinary incontinence, new fecal incontinence, and worsened gait. An MRI showed signs of tethering, including a holocord syrinx. He underwent two untethering surgeries as well syrinx fenestration, and although his gait improved, it remained worse than it had been several months after surgery. The incontinence did not improve. The second patient also developed urinary incontinence a year after SDR. Due to our experience with the first patient, we obtained an MRI immediately and found evidence of tethering. She underwent untethering and her incontinence improved.

CONCLUSION

We report two cases of spinal cord tethering after SDR below the conus, a previously unreported complication. It is important to realize that this complication can occur after SDR.

Placement of leads for stereotactic electroencephalography without the use of anchor bolts: technical note

OBJECTIVE

Stereotactic electroencephalography (SEEG) is an increasingly common technique that neurosurgeons use to help identify the epileptogenic zone. The anchor bolt, which typically secures the electrode to the skull, can be problematic in very thin bone or in electrodes placed in the occiput.

METHODS

A technique is described to place electrodes without the use of an anchor bolt. Accuracy data for entry point, target point, and depth were collected and compared between electrodes placed with and those placed without an anchor bolt.

RESULTS

A total of 58 patients underwent placement of 793 electrodes, of which 25 were boltless. The mean entry and depth errors at target were equivalent, although there was a trend toward greater depth error with boltless electrodes (3.4 mm vs 2.01 mm and 2.59 mm in the bolted groups, respectively). The mean lateral target error was slightly but significantly smaller for boltless electrodes. The majority (60%) of boltless leads were placed into thin temporal squamous bone. The average skull thickness at the entry point for all boltless leads was 1.85 mm.

CONCLUSIONS

Boltless SEEG electrodes can be placed through thin bone, adjacent to a cranial defect, or in the occiput with equivalent accuracy to electrodes placed with anchor bolts.

Magnetic resonance-guided stereotactic laser ablation therapy for the treatment of pediatric brain tumors: a multiinstitutional retrospective study

OBJECTIVE

This study aimed to assess the safety and efficacy of MR-guided stereotactic laser ablation (SLA) therapy in the treatment of pediatric brain tumors.

METHODS

Data from 17 North American centers were retrospectively reviewed. Clinical, technical, and radiographic data for pediatric patients treated with SLA for a diagnosis of brain tumor from 2008 to 2016 were collected and analyzed.

RESULTS

A total of 86 patients (mean age 12.2 ± 4.5 years) with 76 low-grade (I or II) and 10 high-grade (III or IV) tumors were included. Tumor location included lobar (38.4%), deep (45.3%), and cerebellar (16.3%) compartments. The mean follow-up time was 24 months (median 18 months, range 3-72 months). At the last follow-up, the volume of SLA-treated tumors had decreased in 80.6% of patients with follow-up data. Patients with high-grade tumors were more likely to have an unchanged or larger tumor size after SLA treatment than those with low-grade tumors (OR 7.49, p = 0.0364). Subsequent surgery and adjuvant treatment were not required after SLA treatment in 90.4% and 86.7% of patients, respectively. Patients with high-grade tumors were more likely to receive subsequent surgery (OR 2.25, p = 0.4957) and adjuvant treatment (OR 3.77, p = 0.1711) after SLA therapy, without reaching significance. A total of 29 acute complications in 23 patients were reported and included malpositioned catheters (n = 3), intracranial hemorrhages (n = 2), transient neurological deficits (n = 11), permanent neurological deficits (n = 5), symptomatic perilesional edema (n = 2), hydrocephalus (n = 4), and death (n = 2). On long-term follow-up, 3 patients were reported to have worsened neuropsychological test results. Pre-SLA tumor volume, tumor location, number of laser trajectories, and number of lesions created did not result in a significantly increased risk of complications; however, the odds of complications increased by 14% (OR 1.14, p = 0.0159) with every 1-cm3 increase in the volume of the lesion created.

CONCLUSIONS

SLA is an effective, minimally invasive treatment option for pediatric brain tumors, although it is not without risks. Limiting the volume of the generated thermal lesion may help decrease the incidence of complications.

Outcome of hospital discharge on postoperative Day 1 following uncomplicated tethered spinal cord release

OBJECTIVE Postoperative management following the release of simple spinal cord-tethering lesions is highly variable. As a quality improvement initiative, the authors aimed to determine whether an institutional protocol of discharging patients on postoperative day (POD) 1 was associated with a higher rate of postoperative CSF leaks than the prior protocol of discharge on POD 2. METHODS This was a single-center retrospective review of all children who underwent release of a spinal cord-tethering lesion that was not associated with a substantial fascial or dural defect (i.e., simple spinal cord detethering) during 2 epochs: prior to and following the institution of a protocol for discharge on POD 1. Outcomes included the need for and timing of nonroutine care of the surgical site, including return to the operating room, wound suturing, and nonsurgical evaluation and management. RESULTS Of 169 patients identified, none presented with CSF-related complications prior to discharge. In the preintervention group (n = 113), the postoperative CSF leak rate was 4.4% (5/113). The mean length of stay was 2.3 days. In the postintervention group, the postoperative CSF leak rate was 1.9% (1/53) in the patients with postdischarge follow-up. The mean length of stay in that group was 1.3 days. CONCLUSIONS At a single academic children's hospital, a protocol of discharging patients on POD 1 following uncomplicated release of a simple spinal cord-tethering lesion was not associated with an increased rate of postoperative CSF leaks, relative to the previous protocol. The rates identified are consistent with the existing literature. The authors' practice has changed to discharge on POD 1 in most cases.

Cathepsin B-like proteolysis and MARCKS degradation in sub-lethal NMDA-induced collapse of dendritic spines

Sub-lethal excitotoxic injury to dendrites can elicit loss or shrinkage of dendritic spines. Here, we used a cell culture model of sub-lethal NMDA-induced injury to investigate a role for proteolysis in spine collapse. Transient incubation with NMDA-induced spine collapse and spine F-actin loss within 10 min, an effect not mimicked by the actin assembly inhibitor latrunculin A. NMDA-induced spine collapse was significantly attenuated by preincubation with broad-spectrum cysteine protease inhibitors. Results obtained using several class-specific protease inhibitors suggested that this protective effect was due to specific blockade of cathepsin B/L type protease activity, since selective inhibitors of only these proteases significantly attenuated spine loss. Cathepsin B-like immunoreactivity was observed at synaptic sites, but lysosomes were not. Immunoblot analysis showed that MARCKS (myristoylated-alanine-rich C-kinase substrate), a known substrate of cathepsin B, was specifically degraded in response to intense NMDA receptor stimulation. This effect was blocked by preincubation with a cathepsin B-selective inhibitor. Together these data suggest a model in which NMDA-induced spine collapse involves cathepsin B-like proteolysis of MARCKS, and possibly other proteins that regulate the actin-based cytoskeleton.

[Analysis of re-osteosynthesis in femur shaft fractures 1980 to 1989]

Between 1980 and 1989, 210 patients with 212 femoral shaft fractures were treated at our hospital, 191 patients with 193 fractures (91%) had a follow-up control. Of these 193 fractures only 16 required totally 26 (13.5%) reosteosynthesis, with AO-Switzerland performing 625 (14.5%) reosteosynthesis in the same period of time, with the methods of primary fracture care only varying inconsiderably. The different reasons for reinterventions were planned reosteosynthesis, malposition, delayed union and pseudoarthrosis, loose and broken implants and infection. In comparison with AO-Switzerland the main difference was that we had no case with malposition (AO-Switz. 20%) leading to reosteosynthesis. The early infection rate at our hospital was 0.9% (AO-Switz. 2.6%) in comparison to a late infection rate of 2.1% (AO 2.2%). The screw-plate osteosynthesis and reamed femur-nail have both proved to be safe methods for primary fracture care, whereas combined osteosynthesis (e.g. two plates/reamed femur-nail and a plate) has a high rate of reosteosynthesis and therefore should be avoided.

Factors affecting the extension of peritumoural brain oedema. A CT-study

In human brain tumours the extension of peritumoural brain oedema may vary considerably. 37 brain tumours of various pathology and 2 abscesses were examined to identify the factors and mechanisms responsible for the oedema spreading. Peritumoural oedema profiles were determined towards the white matter and ventricle by measuring the CT-numbers of consecutive tissue blocks of 3.0-3.6 mm from the tumour to the normal white matter or the ventricle. It was found that neither the size of the tumour nor the histology has a close relationship to the amount of peritumoural oedema. The distance of oedema spreading rather is determined by the amount of fluid accumulation in the white matter immediately bordering the tumour. This relationship corresponds to a semilogarithmic function and represents the relation between the tumour-adjacent accumulation of extracellular fluid volume and the distance of extracellular fluid movement. The analysis of this relation leads to the suggestion that pressure gradients and bulk flow are involved in the development of human peritumoural oedema.

Attenuation of endotoxin-induced cytotoxicity and prostacyclin production in cultured bovine pulmonary artery endothelial cells by phosphodiesterase inhibition

Exposure of cultured bovine pulmonary endothelial cells to endotoxin (lipopolysaccharide, LPS) causes cytotoxicity and increased prostacyclin production. Since cyclic nucleotides have been proposed as modulators of inflammation, we wondered whether they were involved in LPS-induced endothelial damage. Bovine pulmonary endothelial cells were exposed for 24 h to LPS and the effects of 1-methyl-3-isobutylxanthine (MIX), a phosphodiesterase inhibitor, dibutyryl cyclic AMP (db-cAMP), forskolin (an adenylate cyclase activator), and sodium nitroprusside (an agent known to stimulate intracellular cyclic GMP generation) on LPS-induced injury were determined. Injury was assessed by measurement of lactate dehydrogenase (LDH) (activity) and prostacyclin (6-keto-PGF1 alpha) in the bathing medium. Incubation with MIX attenuated LPS-induced endothelial cytotoxicity and prostacyclin production in a dose-dependent manner (ANOVA, p less than 0.001). Dibutyryl cyclic AMP also inhibited LPS-stimulated LDH release from the endothelial cells but did not suppress increased prostacyclin production. The combinations of MIX and dibutyryl cyclic AMP produced protection similar to that of MIX alone. Neither nitroprusside nor forskolin affected LPS-induced endothelial injury. Measurements of intracellular cyclic nucleotide concentrations showed that MIX caused marked increases in both cyclic AMP and cyclic GMP within 30 min of incubation, while forskolin and nitroprusside failed to cause such early elevations. Thus, phosphodiesterase inhibition protects endothelial cells from the effects of LPS. Increased intracellular concentrations of cyclic AMP also protect endothelial cells from LPS-induced cytotoxicity but do not alter the prostanoid response. We conclude that increased intracellular concentrations of cyclic AMP protect against LPS-induced endothelial cytotoxicity if present early in the exposure. We further conclude that LPS-mediated endothelial cytotoxicity can be separated from increased prostacyclin production.

Erythropoietin and the regulation of erythropoiesis

Recent advances in experimental hematology have provided new insight into the physiology of erythropoiesis. Techniques are now available for cloning in vitro the various hematopoietic progenitor cells of both animals and man. Erythropoietin has been purified and a radioimmunoassay for the hormone has been described. In this paper, we discuss the physiology of erythropoietin and erythropoiesis with special emphasis on data obtained through the employment of new technology.