Aseem Sharma

Perils of intravascular methylprednisolone injection into the vertebral artery. An animal study.

BACKGROUND Intravascular injection of particulate steroids during cervical nerve root blocks has been postulated to be a source of catastrophic neurologic complications that might be avoided with the use of non-particulate steroids. The objective of this study was to compare the effects of direct intravascular injection of particulate and non-particulate steroids on the spinal cord and central nervous system. METHODS Eleven adult pigs underwent direct injection, under fluoroscopic guidance, into the vertebral artery while under general anesthesia. A particulate steroid (methylprednisolone) was injected into four animals (Group 1), whereas seven animals received a non-particulate steroid (dexamethasone in four animals [Group 2] and prednisolone in three [Group 3]). Following injection, the animals were assessed by direct observation of physical activity and with magnetic resonance imaging. After the animals were killed, brain and spinal cord material was retrieved, fixed in paraformaldehyde for one week, and then subjected to histopathologic analysis. RESULTS All four animals in Group 1 failed to regain consciousness after the injection and required ventilatory support. The animals in Groups 2 and 3 recovered fully and demonstrated no evidence of neurologic injury. Magnetic resonance imaging revealed upper cervical cord and brain stem edema in Group 1, but not in Groups 2 and 3. Histologic analysis showed early evidence of hypoxic and ischemic damage-specifically, early eosinophilic neuronal necrosis, nuclear condensation, white-matter pallor, and extracellular edema-in Group 1 but not in Groups 2 and 3. CONCLUSIONS These data suggest that one etiology of neurologic complications following cervical nerve blocks may be inadvertent intravascular injection of particulate steroids, as all animals injected with methylprednisolone had neurologic deficits while none of the controls injected with non-particulate steroids were affected. To our knowledge, this study is the first to demonstrate that particulate steroids cause neurologic deficits and to suggest that use of non-particulate steroids might prevent such complications.

Imaging pattern of intracranial hemorrhage in the setting of posterior reversible encephalopathy syndrome

IntroductionIntracranial hemorrhage (ICH) has been rarely described in the setting of posterior reversible encephalopathy syndrome (PRES). However, existing studies have even more rarely addressed the imaging pattern of PRES-related intracranial hemorrhage. The primary purpose of this study was to define the imaging characteristics of subarachnoid and intraparenchymal hemorrhage in the setting of PRES, including the location of hemorrhage with respect to the regions of parenchymal edema. We also reviewed PRES-related clinical features.MethodsWe conducted a retrospective review of 263 patients with PRES seen at our institution between 2001 and 2008, and identified patients with PRES-related hemorrhage. We reviewed clinical charts and imaging studies of these patients in detail. The clinical data studied included factors predisposing to PRES (such as hypertension, eclampsia, immunosuppressant toxicity, etc.), mean arterial pressure, and coagulation parameters. Imaging characteristics we analyzed included the amount of hemorrhage, its location, multiplicity, and spatial relationship with parenchymal edema.ResultsWe identified a total of 51 patients with PRES-related hemorrhage. The blood pressure was elevated in 80% of these patients, while 47% patients showed coagulopathy. Intraparenchymal hemorrhage (IPH) was present in 46 patients and subarachnoid hemorrhage (SAH) in 14. SAH spared basal cisterns in all patients, and was usually small in amount. IPH was often multifocal, and associated mass effect was rare. In most of the 51 patients, hemorrhage occurred near the parenchymal edema.ConclusionsThe prevalence of ICH in PRES was 19.4% in our series. Both SAH and IPH can occur in association with PRES, typically in a location approximating that of parenchymal edema.

Association between Annular Tears and Disk Degeneration: A Longitudinal Study

BACKGROUND AND PURPOSE: Annular tears and nuclear degeneration often occur concurrently, but their temporal association remains unknown. The purpose of this study was to assess whether annular tears precede nuclear degeneration and whether the evolution of nuclear degeneration is affected by presence of annular tears. MATERIALS AND METHODS: From our radiology report data base, 46 patients with back pain were identified, each with 2 previously obtained lumbar spine MR imaging examinations in the absence of any spinal intervention. Two neuroradiologists evaluated intervertebral disks between the T12 and S1 segments in a random blinded fashion. Hyperintense foci within the anulus were noted to diagnose annular tears. The signal intensity of disks was graded on an ordinal scale, and overall degeneration, on the scale of Pfirrmann et al. Mean signal-intensity and degeneration grades were calculated for disks with and without annular tears, and differences were tested for statistical significance. Mean changes in these grades on follow-up studies were also calculated and compared for 2 groups. RESULTS: The study included 13 men and 33 women, with a mean age of 53.6 ± 15.2 years (range, 20–88 years). The mean interval between the imaging studies was 31.8 months. Annular tears were seen in 203 of 276 (73.5%) disks. Twenty-one of these had normal central signal intensity. Compared with disks without annular tears, disks with annular tears demonstrated significantly higher degeneration grades and a higher change in these grades on follow-up. CONCLUSIONS: Annular tears occur in the early stages of disk degeneration and are associated with a faster subsequent nuclear degeneration.

ACR Appropriateness Criteria Head Trauma

Neuroimaging plays an important role in the management of head trauma. Several guidelines have been published for identifying which patients can avoid neuroimaging. Noncontrast head CT is the most appropriate initial examination in patients with minor or mild acute closed head injury who require neuroimaging as well as patients with moderate to severe acute closed head injury. In short-term follow-up neuroimaging of acute traumatic brain injury, CT and MRI may have complementary roles. In subacute to chronic traumatic brain injury, MRI is the most appropriate initial examination, though CT may have a complementary role in select circumstances. Advanced neuroimaging techniques are areas of active research but are not considered routine clinical practice at this time. In suspected intracranial vascular injury, CT angiography or venography or MR angiography or venography is the most appropriate imaging study. In suspected posttraumatic cerebrospinal fluid leak, high-resolution noncontrast skull base CT is the most appropriate initial imaging study to identify the source, with cisternography reserved for problem solving. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

Association between visual parameters and neuroimaging features of idiopathic intracranial hypertension

BACKGROUND/AIMS Papilledema refers to optic disc swelling resulting from high intracranial pressure (ICP). The precise mechanism by which papilledema occurs remains uncertain. Although orbital neuroimaging features associated with papilledema are well-described, it is unclear whether these findings correlate with visual function. Idiopathic Intracranial Hypertension (IIH) is a condition in which the intracranial pressure is elevated with no obvious cause, causing papilledema and visual loss. The utility of papilledema and IIH neuroimaging findings as a surrogate marker for visual loss, or a predictor of visual loss, is understudied. This retrospective cross-sectional review aims to correlate parameters of visual function with orbital magnetic resonance imaging (MRI) findings. METHODS Patients meeting criteria for IIH who had received orbital imaging within 4 weeks of examination were included. Visual parameters of papilledema grade, visual field mean deviation, and visual acuity were correlated with neuroimaging features, including optic nerve thickness, and optic nerve sheath thickness, among others. All MRI scans were reviewed by a neuroradiologist blinded to clinical status. Spearman rank correlations and t-tests were generated with SAS (v9.2). RESULTS Thirty five patients were included. No significant relationships were found between the main visual parameters of papilledema grade and visual field mean deviation, and MRI findings. CONCLUSIONS We found no significant correlation between visual parameters and imaging features of papilledema. This might indicate that MRI features may provide insight into the structural changes that occur in papilledema, but may not be helpful when making clinical management decisions for patients with IIH in particular, and papilledema in general.

Temporal association of annular tears and nuclear degeneration: lessons from the pediatric population.

BACKGROUND AND PURPOSE: Studies done mainly in adults have shown an association between annular tears and nuclear degeneration. We wanted to study this association in the pediatric population to better understand the natural history of disk degeneration in its early stages. We hypothesized that this association is discernible even at a young age and that annular tears precede nuclear degeneration. MATERIALS AND METHODS: Twenty-six children with back pain and known disk pathology were identified from our radiology report data base. Two neuroradiologists independently evaluated T12 through S1 intervertebral disks in these images. One reader evaluated the disks for the presence and type of annular tears. The other reader graded the signal intensity of the disks on an ordinal scale and the extent of disk degeneration on the Pfirrmann scale. Mean degeneration and signal-intensity grades were compared for disks with radial tears, disks with nonradial tears, and disks without annular tears. RESULTS: Fifty-six disks had radial tears. These demonstrated significantly higher nuclear degeneration grades and greater signal-intensity loss than disks with nonradial tears or disks with no annular tears. About one third (30.3%) of the disks with radial tears had a normal nuclear signal intensity. Only 3% of disks with a signal-intensity grade of ≥3 had an intact annulus. CONCLUSIONS: Nuclear degeneration in children is associated with radial annular tears and rarely occurs in the absence of annular tears.

Hyperintense Optic Nerve Heads on Diffusion-Weighted Imaging: A Potential Imaging Sign of Papilledema

This retrospective review of 19 patients with papilledema and 20 controls sought to determine if optic nerve head DWI hyperintensity was present in the former group. The authors discovered that DWI optic nerve head hyperintensity was significantly associated with papilledema and that when bilateral it was 100% specific for it. Its absence, however, did not exclude papilledema. BACKGROUND AND PURPOSE: Changes at the optic nerve head on DWI in the presence of papilledema have not been systematically studied. The purpose of this study was to evaluate if hyperintensity of ON heads on DWI is associated with papilledema. MATERIALS AND METHODS: In this retrospective study, 19 patients (4 men, 15 women; median age, 32 years) with papilledema and 20 control participants (7 men, 13 women; median age, 48 years) who had undergone prior MR imaging of the brain were identified. Two neuroradiologists blinded to the diagnosis independently reviewed the DWI for the presence of hyperintense signal at the ON head of each eye. If present, they graded the signal as mild or prominent. Groups with and without papilledema were compared for the prevalence of ON head hyperintensity by using the Fisher exact test, with analyses performed both for groups of patients and for individual eyes. Presence of ON head hyperintensity was also studied as a function of Frisen papilledema grade on fundoscopy, when available. RESULTS: Hyperintensity of the ON heads on DWI was significantly associated with papilledema (P = .001). For the 2 readers, hyperintensity at both ON heads was 26.3% and 42.1% sensitive and 100% specific in the detection of papilledema. The presence of unilateral ON head hyperintensity was not specific for papilledema and was invariably graded as mild when seen in the control group. Patients with higher papilledema grades had a higher prevalence of hyperintensity at the ON heads. CONCLUSIONS: Hyperintensity of the ON heads on DWI can serve as a useful imaging marker for papilledema, especially if bilateral. Its absence, however, does not exclude papilledema.

Correlation between papilledema grade and diffusion-weighted magnetic resonance imaging in idiopathic intracranial hypertension.

Background: To explore the relationship between diffusion-weighted magnetic resonance imaging (DWI) hyperintensity of the optic nerve head (ONH) and papilledema grade in patients with idiopathic intracranial hypertension (IIH). Methods: A retrospective chart review was conducted of patients with definitively diagnosed IIH by clinical examination and visual field (VF) analysis who underwent orbital magnetic resonance imaging (MRI) within 4 weeks of diagnosis. A neuroradiologist masked to the diagnosis assessed the results of DWI for each eye independently and graded the signal intensity of the ONH into none, mild, and prominent categories. DWI grading was compared with papilledema grade and visual field mean deviation (VFMD) by Spearman rank correlation analysis and t-tests. Results: Forty-two patients were included in the study. A statistically significant difference (P = 0.0195) was found between papilledema grade and patients with prominent DWI findings (n = 16; mean papilledema grade 3.75 ± 1.25) vs mild or no ONH hyperintensity (n = 26; mean papilledema grade 2.79 ± 1.24) at the time of initial diagnosis. DWI hyperintensity of the ONH at diagnosis was also found to be significantly correlated with the degree of papilledema at follow-up (&rgr; = 0.39, P = 0.0183) but not with VFMD. Conclusions: We found a significant correlation between the severity of papilledema and ONH hyperintensity on DWI in patients with IIH but not with VF loss or other visual parameters. These findings may offer insight into the pathophysiology of papilledema in IIH and provide a surrogate marker for the presence and severity of papilledema.

Temporal interactions of degenerative changes in individual components of the lumbar intervertebral discs: a sequential magnetic resonance imaging study in patients less than 40 years of age.

Study Design. A retrospective longitudinal observational study using baseline and follow-up magnetic resonance imaging (MRI). Objective. To study the natural history of disc degeneration, focusing on the significance of changes affecting the individual components of the intervertebral disc. Summary of Background Data. The natural history of the degenerative disc disease is poorly understood. Focusing on the relative prevalence, temporal evolution, and interactions of pathology in the anulus fibrosus, nucleus pulposus, and the end plates can help in better understanding of this process. Methods. MRIs of the lumbar spine in 63 patients, obtained at a mean interval of 30 months, were evaluated independently by two neuroradiologists to assess the temporal evolution of degeneration changes in 378 discs between T12 through S1 segments. In addition, a direct side-by-side comparison of two studies was also performed. Statistical analysis was performed to assess the association between the degeneration of individual disc components and to find the predictors of future degeneration. Results. Radial anular tears and end plate defects were associated with worse nuclear degeneration at the time of the initial study. Both end plate defects and nuclear degeneration were rare in the absence of radial tears. Multiple nominal logistic regression analysis showed that radial tears and herniation at the time of the initial study, along with the duration between the two imaging studies were the significant predictors of worsening nuclear degeneration. Age, sex, and the segmental disc level did not show any significant association with temporal progression of nuclear degeneration. Conclusion. Radial tears and herniation are significant predictors of progressive nuclear degeneration, which was not seen in the absence of radial tears. End plate defects also frequently occur before nuclear degeneration but rarely in the absence of anular tears.

A Two-Tiered Approach to MRI for Hearing Loss: Incremental Cost of a Comprehensive MRI Over High-Resolution T2-Weighted Imaging

OBJECTIVE The objective of our study was to compare the cost-effectiveness of two approaches to using MRI for the evaluation of patients with hearing loss. MATERIALS AND METHODS We developed a decision tree to compare the cost-effectiveness of conventional MRI with that of a proposed two-tiered model in which an initial 3D T2-weighted imaging examination was used to determine the need for comprehensive MR scanning. Three radiologists independently and blindly reviewed the 3D T2-weighted images acquired as part of the comprehensive MR examinations of 256 patients with hearing loss to assess the diagnostic efficacy of the two-tiered approach. Costs were defined in terms of both the scanner utilization time for the imaging facility and the dollar amount for payers. Effectiveness was defined in terms of the ability to correctly detect the presence or absence of disease. RESULTS The conventional approach was less cost-effective, with a baseline incremental cost-effectiveness ratio (ICER) of 27,299 minutes of scanner utilization per unit increase in effectiveness. Assuming a 50% reduction in the reimbursement of the technical component from the current level by the Centers for Medicare & Medicaid Services, this result reflected an ICER of