Christopher M. Holland

Spatial Distribution of White-Matter Hyperintensities in Alzheimer Disease, Cerebral Amyloid Angiopathy, and Healthy Aging

Background and Purpose— White-matter hyperintensities (WMHs) detected by magnetic resonance imaging are thought to represent the effects of cerebral small-vessel disease and neurodegenerative changes. We sought to determine whether the spatial distribution of WMHs discriminates between different disease groups and healthy aging individuals and whether these distributions are related to local cerebral perfusion patterns. Methods— We examined the pattern of WMHs by T2/fluid-attenuated inversion recovery–weighted magnetic resonance imaging in 3 groups of subjects: cerebral amyloid angiopathy (n=32), Alzheimer disease or mild cognitive impairment (n=41), and healthy aging (n=29). WMH frequency maps were calculated for each group, and spatial distributions were compared by voxel-wise logistic regression. WMHs were also analyzed as a function of normal cerebral perfusion patterns by overlaying a single photon emission computed tomography atlas. Results— Although WMH volume was greater in cerebral amyloid angiopathy and Alzheimer disease/mild cognitive impairment than in healthy aging, there was no consistent difference in the spatial distributions when controlling for total WMH volume. Hyperintensities were most frequent in the deep periventricular WM in all 3 groups. A strong inverse correlation between hyperintensity frequency and normal perfusion was demonstrated in all groups, demonstrating that WMHs were most common in regions of relatively lower normal cerebral perfusion. Conclusions— WMHs show a common distribution pattern and predilection for cerebral WM regions with lower atlas-derived perfusion, regardless of the underlying diagnosis. These data suggest that across diverse disease processes, WM injury may occur in a pattern that reflects underlying tissue properties, such as relative perfusion.

Cognitive dysfunction in patients with clinically isolated syndromes or newly diagnosed multiple sclerosis

Cognitive dysfunction is common in patients with multiple sclerosis (MS), and has been associated with MRI measures of lesion burden and atrophy. Little is known about the prevalence of cognitive impairment in patients with early MS. The associations between cognitive impairment and MRI measures of disease severity early in the disease course are also unclear. This study used a brief battery of cognitive tests to determine the prevalence and pattern of cognitive impairment in patients with clinically isolated syndromes or newly diagnosed MS. The associations between cognitive impairment and MRI measures of disease severity early in the disease course were also examined. Ninety-two patients with clinically isolated syndromes or the diagnosis of MS within the last 3 years participating in the CLIMB study underwent a neurologic examination, neuropsychological evaluation and MRI at 1.5T. Forty-nine percent of patients were impaired on one or more cognitive measures. There were no significant correlations between cognitive scores and MRI measures of disease severity including total T2 lesion volume, normal appearing white matter volume, grey matter volume, and brain parenchymal fraction. These findings suggest that cognitive impairment may predate the appearance of gross structural abnormalities on MRI and serve as an early marker of disease activity in MS. Multiple Sclerosis 2007; 13: 1004—1010. http://msj.sagepub.com

Reduction in cerebral blood flow in areas appearing as white matter hyperintensities on magnetic resonance imaging

The purpose of this study was to examine cerebral blood flow (CBF) as measured by arterial spin labeling (ASL) in tissue classified as white matter hyperintensities (WMH), normal appearing white matter, and grey matter. Seventeen healthy older adults received structural and ASL MRI. Cerebral blood flow was derived for three tissue types: WMH, normal appearing white matter, and grey matter. Cerebral blood flow was lower in WMH areas relative to normal appearing white matter, which in turn, was lower than grey matter. Regions with consistently lower CBF across individuals were more likely to appear as WMH. Results are consistent with an emerging literature linking diminished regional perfusion with the risk of developing WMH.

The relationship between normal cerebral perfusion patterns and white matter lesion distribution in 1,249 patients with multiple sclerosis.

The pathological differences underlying the clinical disease phases in multiple sclerosis (MS) are poorly characterized. We sought to explore the relationship between the distribution of white matter (WM) lesions in relapsing‐remitting (RR) and secondary progressive (SP) MS and the normal regional variability of cerebral perfusion.

Atlas-derived perfusion correlates of white matter hyperintensities in patients with reduced cardiac output.

Reduced cardiac output is associated with increased white matter hyperintensities (WMH) and executive dysfunction in older adults, which may be secondary to relations between systemic and cerebral perfusion. This study preliminarily describes the regional distribution of cerebral WMH in the context of a normal cerebral perfusion atlas and aims to determine if these variables are associated with reduced cardiac output. Thirty-two participants (72 ± 8 years old, 38% female) with cardiovascular risk factors or disease underwent structural MRI acquisition at 1.5T using a standard imaging protocol that included FLAIR sequences. WMH distribution was examined in common anatomical space using voxel-based morphometry and as a function of normal cerebral perfusion patterns by overlaying a single photon emission computed tomography (SPECT) atlas. Doppler echocardiogram data was used to dichotomize the participants on the basis of low (n=9) and normal (n=23) cardiac output. Global WMH count and volume did not differ between the low and normal cardiac output groups; however, atlas-derived SPECT perfusion values in regions of hyperintensities were reduced in the low versus normal cardiac output group (p<0.001). Our preliminary data suggest that participants with low cardiac output have WMH in regions of relatively reduced perfusion, while normal cardiac output participants have WMH in regions with relatively higher regional perfusion. This spatial perfusion distribution difference for areas of WMH may occur in the context of reduced systemic perfusion, which subsequently impacts cerebral perfusion and contributes to subclinical or clinical microvascular damage.

Interhospital Transfer of Neurosurgical Patients to a High-Volume Tertiary Care Center: Opportunities for Improvement.

BACKGROUND Neurosurgical indications for patient transfer include absence of local or available neurosurgical coverage, subspecialty or interdisciplinary requirements, and family preference. Transfer of patients to regional centers will increase with further centralization of medical care. OBJECTIVE To report the transfer records of a large tertiary care center to identify trends, failures, and opportunities to improve interhospital transfer of neurosurgical patients. METHODS All consecutive, prospectively documented requests for interhospital patient transfer to the adult neurosurgical service of Emory University Hospitals were retrospectively identified from a centralized transfer center database for a 1-year study period. RESULTS Requests for neurosurgical care constituted 1323 of the 9087 calls (14.6%); 81.1% of these requests were accepted, and a total of 984 patients (74.4%) arrived at our institutions. Patients arrived from 133 unique facilities throughout a catchment area of 66 287 sq miles. Although the median travel time for transfer patients was 36 minutes, the median interval between the request and patient arrival was 4 hours 2 minutes. The most frequent diagnoses were intracranial hemorrhage (31.8%), subarachnoid hemorrhage (31.2%), and intracranial tumor (15.2%). The overall diagnostic error rate was 10.3%. Only 42.5% of patients underwent neurosurgical intervention, and 57 patients admitted to intensive care were immediately transitioned to a lower level of care. CONCLUSION Interhospital transfer requires a coordinated effort among hospital administrators, physicians, and staff to make complex decisions that govern this important and costly process. These data suggest common failures and numerous opportunities for improvement in transfer efficiency, diagnostic accuracy, triage, and resource allocation.

Posterior cervical spinal fusion in a 3-week-old infant with a severe subaxial distraction injury

Unstable spinal injuries in the neonate pose particular challenges in the clinical and radiographic assessment as well as the surgical stabilization of the spine. In this report, the authors present the unfortunate case of a 3-week-old infant who suffered a severe subaxial cervical fracture dislocation with spinal cord injury that occurred as a result of nonaccidental trauma. Imaging demonstrated severe distraction at C5-6 and near-complete spinal cord transection resulting in quadri-paresis. Open surgical reduction was performed with noninstrumented posterior fusion augmented with split rib autograft and recombinant human bone morphogenetic protein-2. Postoperative imaging demonstrated progressive bony fusion at 2 months, and clinical examination findings progressed to a motor examination classification of ASIA C. At 2 years, the fusion mass is stable and cervical alignment is maintained. The patient remains flaccid in the bilateral lower extremities, but has movement with some dexterity in both hands. Follow-up MRI shows severe spinal cord injury with evidence of bilateral C-5 nerve root avulsions. This case represents the first report of spinal fusion in an infant of less than 1 month of age. Given the extreme young age of the patient, the diagnostic challenges as well as the mechanical and technical considerations of surgical fusion are discussed.

Magnetic resonance imaging of traumatic injury to the craniovertebral junction: a case-based review.

OBJECT The craniovertebral junction (CVJ) is unique in the spinal column regarding the degree of multiplanar mobility allowed by its bony articulations. A network of ligamentous attachments provides stability to this junction. Although ligamentous injury can be inferred on CT scans through the utilization of craniometric measurements, the disruption of these ligaments can only be visualized directly with MRI. Here, the authors review the current literature on MRI evaluation of the CVJ following trauma and present several illustrative cases to highlight the utility and limitations of craniometric measures in the context of ligamentous injury at the CVJ. METHODS A retrospective case review was conducted to identify patients with cervical spine trauma who underwent cervical MRI and subsequently required occipitocervical or atlantoaxial fusion. Craniometric measurements were performed on the CT images in these cases. An extensive PubMed/MEDLINE literature search was conducted to identify publications regarding the use of MRI in the evaluation of patients with CVJ trauma. RESULTS The authors identified 8 cases in which cervical MRI was performed prior to operative stabilization of the CVJ. Craniometric measures did not reliably rule out ligamentous injury, and there was significant heterogeneity in the reliability of different craniometric measurements. A review of the literature revealed several case series and descriptive studies addressing MRI in CVJ trauma. Three papers reported the inadequacy of the historical Traynelis system for identifying atlantooccipital dislocation and presented 3 alternative classification schemes with emphasis on MRI findings. CONCLUSIONS Recognition of ligamentous instability at the CVJ is critical in directing clinical decision making regarding surgical stabilization. Craniometric measures appear unreliable, and CT alone is unable to provide direct visualization of ligamentous injury. Therefore, while the decision to obtain MR images in CVJ trauma is largely based on clinical judgment with craniometric measures used as an adjunct, a high degree of suspicion is warranted in the care of these patients as a missed ligamentous injury can have devastating consequences.

Association of Overlapping Surgery With Patient Outcomes in a Large Series of Neurosurgical Cases

Importance Overlapping surgery (OS) is common. However, there is a dearth of evidence to support or refute the safety of this practice. Objective To determine whether OS is associated with worsened morbidity and mortality in a large series of neurosurgical cases. Design, Setting, and Participants A retrospective cohort study was completed for patients who underwent neurosurgical procedures at Emory University Hospital, a large academic referral hospital, between January 1, 2014, and December 31, 2015. Patients were operated on for pathologies across the spectrum of neurosurgical disorders. Propensity score weighting and logistic regression models were executed to compare outcomes for patients who received nonoverlapping surgery and OS. Investigators were blinded to study cohorts during data collection and analysis. Main Outcomes and Measures The primary outcome measures were 90-day postoperative mortality, morbidity, and functional status. Results In this cohort of 2275 patients who underwent neurosurgery, 1259 (55.3%) were female, and the mean (SD) age was 52.1 (16.4) years. A total of 972 surgeries (42.7%) were nonoverlapping while 1303 (57.3%) were overlapping. The distribution of American Society of Anesthesiologists score was similar between nonoverlapping surgery and OS cohorts. Median surgical times were significantly longer for patients in the OS cohort vs the nonoverlapping surgery cohort (in-room time, 219 vs 188 minutes; skin-to-skin time, 141 vs 113 minutes; both P < .001). Overlapping surgery was more frequently elective (93% vs 87%; P < .001). Regression analysis failed to demonstrate an association between OS and complications, such as mortality, morbidity, or worsened functional status. Measures of baseline severity of illness, such as admission to the intensive care unit and increased length of stay, were associated with mortality (intensive care unit: odds ratio [OR], 25.5; 95% CI, 6.22-104.67; length of stay: OR, 1.03; 95% CI, 1.00-1.05), morbidity (intensive care unit: OR, 1.85; 95% CI, 1.43-2.40; length of stay: OR, 1.06; 95% CI, 1.04-1.08), and unfavorable functional status (length of stay: OR, 1.03; 95% CI, 1.02-1.05). Conclusions and Relevance These data suggest that OS can be safely performed if appropriate precautions and patient selection are followed. Data such as these will help determine health care policy to maximize patient safety.

Thoracic lateral extracavitary corpectomy for anterior column reconstruction with expandable and static titanium cages: Clinical outcomes and surgical considerations in a consecutive case series

OBJECTIVE Many surgical interventions have emerged as effective means of restoring mechanical stability of the anterior column of the spine. The lateral extracavitary approach (LECA) allows for broad visualization and circumferential reconstruction of the spinal column. However, early reports demonstrated significant complication rates, protracted operative times, and prolonged hospitalizations. More recent reports have highlighted concerns for subsidence, particularly with expandable cages. Our work seeks to describe a single-surgeon consecutive series of patients undergoing LECA for thoracic corpectomy. Specifically, the objective was to explore the surgical considerations, clinical and radiographic outcomes, and complication profile of this approach. METHODS A retrospective study examined data from 17 consecutive patients in whom single or multi-level corpectomy was performed via a LECA by a single surgeon. Vertebral body replacement was achieved with either a static or expandable titanium cage. The Karnofsky Performance Scale (KPS) was utilized to assess patient functional status before and after surgery. Radiographic outcomes, particularly footplate-to-body ratio and subsidence, were assessed on CT imaging at 6 weeks after surgery and at follow-up of at least 6 months. RESULTS The majority of patients had post-operative KPS scores consistent with functional independence (≥70, 12/17 patients, 71%). Fourteen patients had improved or maintained function by last follow-up. In both groups, all patients had a favorable footplate-to-body ratio, and rates of subsidence were similar at both time points. Notably, the overall complication rate (24%) was significantly lower than that published in the literature, and no patient suffered a pneumothorax that required placement of a thoracostomy tube. CONCLUSION The LECA approach for anterior column reconstruction with static or expandable cages is an important surgical consideration with favorable surgical parameters and complication rates. Further, use of expandable cages may allow for reconstruction over a larger segment without increased risk of subsidence.