Publications by authors named "Eric M Nyberg"

9 Publications

  • Page 1 of 1

RadExam Turns 1: Offering Solutions to Radiology Residencies.

J Am Coll Radiol 2019 Sep 17;16(9 Pt A):1206-1210. Epub 2019 Apr 17.

Geisel School of Medicine, Dartmouth University, Hanover, New Hampshire.

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September 2019

Beyond the embolus: "do not miss" diffusion abnormalities of ischaemic and non-ischaemic neurological disease.

Insights Imaging 2017 Dec 6;8(6):573-580. Epub 2017 Oct 6.

Department of Radiology, University of Colorado School of Medicine, Aurora, CO, 80045, USA.

Given the rapid evolution and technological advances in the diagnosis and treatment of acute ischaemic stroke (AIS), including the proliferation of comprehensive stroke centres and increasing emphasis on interventional stroke therapies, the need for prompt recognition of stroke due to acute large vessel occlusion has received significant attention in the recent literature. Diffusion-weighted imaging (DWI) is the gold standard for the diagnosis of acute ischaemic stroke, as images appear positive within minutes of ischaemic injury, and a high signal-to-noise ratio enables even punctate infarcts to be readily detected. DWI lesions resulting from a single arterial embolic occlusion or steno-occlusive lesion classically lateralise and conform to a specific arterial territory. When there is a central embolic source (e.g. left atrial thrombus), embolic infarcts are often found in multiple vascular territories. However, ischaemic disease arising from aetiologies other than arterial occlusion will often not conform to an arterial territory. Furthermore, there are several important entities unrelated to ischaemic disease that can present with abnormal DWI and which should not be confused with infarct. This pictorial review explores the scope and typical DWI findings of select neurologic conditions beyond acute arterial occlusion, which should not be missed or misinterpreted.

Teaching Points: • DWI abnormalities due to acute arterial occlusion must be promptly identified. • DWI abnormalities not due to arterial occlusion will often not conform to an arterial territory. • Several important non-ischaemic entities can present on DWI and should not be confused with infarct.
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December 2017

The Addition of Endovascular Intervention for Dural Venous Sinus Thrombosis: Single-Center Experience and Review of Literature.

J Stroke Cerebrovasc Dis 2017 Oct 9;26(10):2240-2247. Epub 2017 Jun 9.

Department of Neurology, University of Colorado, Aurora, Colorado. Electronic address:

Background: Dural venous sinus thrombosis (DVST) is a cause of infarction and intracranial hemorrhage (ICH) that can lead to significant morbidity. Endovascular therapy has emerged as an adjunctive therapy in select cases but has been associated with increased hemorrhagic complications. We present our experience with a large single-center cohort of DVST cases treated with current-generation thrombectomy devices.

Materials And Methods: In this retrospective cohort study, a chart review was performed to compare presentations and outcomes of patients treated with anticoagulation alone with those treated with additional interventional therapy, using the modified Rankin Scale (mRS) score at discharge and at 90 days' follow-up.

Results: A total of 66 patients were included; 37 were treated with anticoagulation alone, and 29 underwent additional interventional therapy. Patients presenting with ICH or infarction had a significantly greater likelihood of disability at the time of discharge (odds ratio [OR] of 64.5 and 45.8, respectively; P < .0001) and at 90 days (OR of 28.4 and 22.8, respectively; P < .0001). Patients presenting with ICH or infarction were more likely to be selected for endovascular therapy (P < .05). Endovascular therapy was typically performed within 24 hours of admission; 9 patients (31%) had post-treatment hemorrhage, with 2 being (6.9%) symptomatic. There were fewer patients with slight disability (mRS score ≤1) in the endovascular group compared with the anticoagulation group at discharge (P = .05), but outcomes were not significantly different at 90 days (P = .19).

Conclusions: Despite a higher rate of ICH or infarction at presentation in the endovascular group and an increased risk of postprocedural ICH, both treatment groups had similarly good functional outcomes at 90 days.
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October 2017

Cement technique correlates with tuberosity healing in hemiarthroplasty for proximal humeral fracture.

J Shoulder Elbow Surg 2017 Mar 7;26(3):437-442. Epub 2016 Oct 7.

Department of Orthopaedics, Southern California Permanente Medical Group, Harbor City, CA, USA.

Background: Tuberosity healing correlates with clinical outcomes after hemiarthroplasty for 4-part proximal humeral fractures (4PHFs). We seek to examine variables that affect tuberosity healing.

Methods: This was a retrospective comparative study. At 1 year postoperatively, patients who underwent hemiarthroplasty for 4PHFs were divided into 2 groups: those with anatomically healed tuberosities and those with tuberosity nonunion. The primary variables included time between injury and surgery, prosthesis fenestration, cement mantle classification, and both vertical and horizontal tuberosity reduction. Secondary demographic factors included age, gender, osteoporosis status, diabetes status, and smoking status.

Results: There were 84 individuals who met the inclusion criteria: 37 (44%) had anatomically healed tuberosities, and 47 (56%) did not. Individuals with anatomic healing had cement near or under the tuberosities 32% of the time, whereas individuals with nonunion or resorption had cement near the tuberosities 66% of the time (P = .002). There was no association between tuberosity healing and fenestration of the humeral stem (P = .84). Anatomic reduction between tuberosities was associated with healing (P <.001), whereas greater tuberosity-to-head height was not (P = .25). There were no significant differences in age, osteoporosis status, smoking status, diabetes status, or time to surgery between groups. Male patients had nearly double the rate of healing (P = .03).

Discussion And Conclusion: The classification and effect of cement technique on tuberosity healing have not previously been described. We suggest limiting cementation to a minimum of 5 mm below the level of the tuberosity fracture. The ideal candidate for hemiarthroplasty for a 4PHF is a male patient with anatomic tuberosity reduction and limited use of cement.
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March 2017

Postoperative Risk of Hepatic Decompensation after Orthopedic Surgery in Patients with Cirrhosis.

J Clin Transl Hepatol 2016 Jun 15;4(2):83-9. Epub 2016 Jun 15.

Department of Orthopaedics, Kaiser Permanente, San Diego, USA; Department of Orthopaedics, University of California at San Diego, San Diego, USA.

Background And Aims: Previous studies have shown increased hepatic decompensation in patients with cirrhosis undergoing surgery. However, there are little data available in cirrhotics undergoing orthopedic surgery compared to cirrhotics who did not undergo surgery. The aim of this study was to examine the demographics, comorbid conditions, and clinical factors associated with hepatic decompensation within 90 days in cirrhotics who underwent orthopedic surgery.

Methods: This is a retrospective matched cohort study. Inclusion criteria were cirrhosis diagnosis, age > 18 years, ≥ 6 months continuous health plan membership, and a procedure code for orthopedic surgery. Up to five cirrhotic controls without orthopedic surgery were matched on age, gender, and cirrhosis diagnosis date. Data abstraction was performed for demographics, socioeconomics, clinical, and decompensation data. Chart review was performed for validation. Multivariable analysis estimated relative risk of decompensation.

Results: Eight hundred fifty-three orthopedic surgery cases in cirrhotics were matched with 4,263 cirrhotic controls. Among the cases and matched controls, the mean age was 60.5 years, and 52.2% were female. Within 90 days after surgery, cases had more decompensation compared to matched controls (12.8% vs 4.9%). Using multivariable analysis, orthopedic surgery, a 0.5 g/dL decrease in serum albumin, and a 1-unit increase in Charlson Comorbidity Index were associated with a significant increase in decompensation within 90 days of surgery. Diabetes, chronic obstructive pulmonary disease, and chronic kidney disease were seen with increased frequency in cases vs. matched controls.

Conclusions: Cirrhotics who underwent orthopedic surgery had a significant increase in hepatic decompensation within 90 days of surgery compared to matched controls. An incremental decrease in serum albumin and an incremental increase in the Charlson Comorbidity Index were significantly associated with hepatic decompensation after surgery.
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June 2016

Morphologic changes in the mesolimbic pathway in Parkinson's disease motor subtypes.

Parkinsonism Relat Disord 2015 May 13;21(5):536-40. Epub 2015 Mar 13.

Department of Neurology, University of Colorado Denver, Aurora, CO, United States. Electronic address:

Background: Parkinson's disease (PD) is a common neurodegenerative disorder associated with gray matter atrophy. Cortical atrophy patterns may further help distinguish between PD motor subtypes. Comparable differences in subcortical volumes have not been found.

Methods: Twenty-one cognitively intact and treated PD patients, including 12 tremor dominant (TD) subtype, Nine postural instability gait dominant (PIGD) subtype, and 20 matched healthy control subjects underwent 3.0 T high-resolution structural MRI scanning. Subcortical volumetric analysis was performed using FreeSurfer and shape analysis was performed with FIRST to assess for differences between PD patients and controls and between PD subtypes.

Results: No significant differences in subcortical volumes were found between motor PD subtypes, but comparing grouped PD patients with controls revealed a significant increase in hippocampal volume in PD patients (p = 0.03). A significant shape difference was detected in the right nucleus accumbens (NAcc) between PD and controls and between motor subtypes. Shape differences were driven by positive deviations in the TD subtype. Correlation analysis revealed a trend between hippocampal volume and decreasing MDS-UPDRS (p = 0.06).

Conclusion: While no significant differences in subcortical volumes between PD motor subtypes were found, increased hippocampal volumes were observed in PD patients compared to controls. Right NAcc shape differences in PD patients were driven by changes in the TD subtype. These unexpected findings may be related to the effects of chronic dopaminergic replacement on the mesolimbic pathway. Further studies are needed to replicate and determine the clinical significance of such morphologic changes.
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May 2015

The Dotter method revisited: early experience with a novel method of rapid internal carotid artery revascularization in the setting of acute ischemic stroke.

J Neurointerv Surg 2016 Apr 30;8(4):360-6. Epub 2015 Jan 30.

Department of Radiology, University of Colorado, Aurora, Colorado, USA.

Background: Tandem occlusive disease in the setting of acute ischemic stroke involving cervical and cerebral arteries has been associated with poor neurological outcome and poses significant challenges to neurointerventionists. Previously described endovascular methods typically involve carotid revascularization with stent placement prior to or following intracranial thrombectomy. Stent-based approaches, however, require the use of antiplatelet therapy which may increase the risk of hemorrhagic transformation. We describe a novel modified Dotter technique which may be used for carotid revascularization in lieu of stenting. This technique can eliminate the need for antiplatelet therapy, reduce procedure times, and possibly reduce hemorrhagic conversion rates.

Methods: Seven patients presenting between April 2013 and January 2014 were treated with this technique. All patients had carotid stenosis of 65-100% and tandem middle cerebral artery occlusions. National Institutes of Health (NIH) Stroke Scale scores as well as clinical and procedural times were recorded. Pre- and post-Dotter stenosis was measured using the NASCET criteria. Follow-up imaging and clinical data were reviewed.

Results: The mean age was 64 years and mean initial NIH Stroke Scale score was 11.7. Mean groin to recanalization time was 26 min. Thrombolysis In Cerebral Infarction grade 2b-3 was achieved in all patients. The mean stenosis was 88% preoperatively and 61% postoperatively. There were no intracranial hemorrhages. The modified Rankin Scale score was 0 in six patients (86%) and 6 in one patient (14%).

Conclusions: The Dotter stroke technique is a feasible and safe alternative to carotid stenting in the setting of acute ischemic stroke and may reduce the risk of hemorrhagic conversion. No re-occlusion occurred during follow-up in patients with post-Dotter stenosis ≤65%.
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April 2016

Beneficial remodeling of small saccular intracranial aneurysms after staged stent only treatment: a case series.

J Stroke Cerebrovasc Dis 2014 Jan 13;23(1):80-5. Epub 2012 Nov 13.

Intermountain Neurosugery, St. Anthony's Hospital, Denver, Colorado.

Background: We evaluated the effect of stent alone treatment for small intracranial aneurysms that were not amenable to coil embolization without prior stent reconstruction.

Methods: This case series was conducted in the neurosurgical service at a tertiary care hospital in Denver, Colorado. Nine patients were electively treated for intracranial aneurysms. All patients had a single low porosity stent reconstruction device placed across the neck of a small intracranial aneurysm. The main outcome measures were changes in aneurysm size and parent vessel morphology during follow-up.

Results: Nine patients underwent stent alone treatment for unruptured intracranial aneurysms. The mean follow-up period was 9.6 months (range 6-17 months). There were no cases of periprocedural morbidity or aneurysm rupture during follow-up. All aneurysms decreased in size, and 3 of 9 aneurysms were gone at follow-up. In addition, at follow-up all parent vessels demonstrated straightening about the aneurysm site.

Conclusions: Beneficial remodeling with a decrease in the size of small intracranial aneurysms may be seen after treatment with a single stent alone, particularly if the aneurysm arises at an arterial bend or bifurcation. This phenomenon may be related to a degree of straightening of the parent artery, improving hemodynamic conditions about the aneurysm site.
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January 2014

Systemic to pulmonary venous shunt: imaging findings and clinical presentations.

J Thorac Imaging 2008 Aug;23(3):170-7

Department of Radiology, University Hospitals-Case Medical Center, Cleveland, OH, USA.

Multislice computed tomography technology has enabled sophisticated insights into the evaluation of collateral venous pathways in the thorax. A small but well-established body of literature has described the multiple venous pathways in patients with central venous obstruction. In unusual circumstances, however, physiologically maladaptive pathways have been described involving systemic to pulmonary venous shunts. This paper describes 21 patients with systemic to pulmonary venous shunts having a wide spectrum of etiologies. Clinical presentations typically include cardiopulmonary symptomatology and paradoxical emboli. Ultrafast magnetic resonance and multislice computed tomography established the diagnosis of this uncommon but important entity.
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August 2008