Mark E. Jentoft

Intracranial Gadolinium Deposition after Contrast-enhanced MR Imaging

PURPOSE To determine if repeated intravenous exposures to gadolinium-based contrast agents (GBCAs) are associated with neuronal tissue deposition. MATERIALS AND METHODS In this institutional review board-approved single-center study, signal intensities from T1-weighted magnetic resonance (MR) images and postmortem neuronal tissue samples from 13 patients who underwent at least four GBCA-enhanced brain MR examinations between 2000 and 2014 (contrast group) were compared with those from 10 patients who did not receive GBCA (control group). Antemortem consent was obtained from all study participants. Neuronal tissues from the dentate nuclei, pons, globus pallidus, and thalamus of these 23 deceased patients were harvested and analyzed with inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy, and light microscopy to quantify, localize, and assess the effects of gadolinium deposition. Associations between cumulative gadolinium dose, changes in T1-weighted MR signal intensity, and ICP-MS-derived tissue gadolinium concentrations were examined by using the Spearman rank correlation coefficient (ρ). RESULTS Compared with neuronal tissues of control patients, all of which demonstrated undetectable levels of gadolinium, neuronal tissues of patients from the contrast group contained 0.1-58.8 μg gadolinium per gram of tissue, in a significant dose-dependent relationship that correlated with signal intensity changes on precontrast T1-weighted MR images (ρ = 0.49-0.93). All patients in the contrast group had relatively normal renal function at the time of MR examination. Gadolinium deposition in the capillary endothelium and neural interstitium was observed only in the contrast group. CONCLUSION Intravenous GBCA exposure is associated with neuronal tissue deposition in the setting of relatively normal renal function. Additional studies are needed to investigate the clinical significance of these findings and the generalizability to other GBCAs. Online supplemental material is available for this article.

Gadolinium Deposition in Human Brain Tissues after Contrast-enhanced MR Imaging in Adult Patients without Intracranial Abnormalities

Purpose To determine whether gadolinium deposits in neural tissues of patients with intracranial abnormalities following intravenous gadolinium-based contrast agent (GBCA) exposure might be related to blood-brain barrier integrity by studying adult patients with normal brain pathologic characteristics. Materials and Methods After obtaining antemortem consent and institutional review board approval, the authors compared postmortem neuronal tissue samples from five patients who had undergone four to 18 gadolinium-enhanced magnetic resonance (MR) examinations between 2005 and 2014 (contrast group) with samples from 10 gadolinium-naive patients who had undergone at least one MR examination during their lifetime (control group). All patients in the contrast group had received gadodiamide. Neuronal tissues from the dentate nuclei, pons, globus pallidus, and thalamus were harvested and analyzed with inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy with energy-dispersive x-ray spectroscopy, and light microscopy to quantify, localize, and assess the effects of gadolinium deposition. Results Tissues from the four neuroanatomic regions of gadodiamide-exposed patients contained 0.1-19.4 μg of gadolinium per gram of tissue in a statistically significant dose-dependent relationship (globus pallidus: ρ = 0.90, P = .04). In contradistinction, patients in the control group had undetectable levels of gadolinium with ICP-MS. All patients had normal brain pathologic characteristics at autopsy. Three patients in the contrast group had borderline renal function (estimated glomerular filtration rate <45 mL/min/1.73 m2) and hepatobiliary dysfunction at MR examination. Gadolinium deposition in the contrast group was localized to the capillary endothelium and neuronal interstitium and, in two cases, within the nucleus of the cell. Conclusion Gadolinium deposition in neural tissues after GBCA administration occurs in the absence of intracranial abnormalities that might affect the permeability of the blood-brain barrier. These findings challenge current understanding of the biodistribution of these contrast agents and their safety.

Immunohistochemistry is highly sensitive and specific for detection of BRAF V600E mutation in pleomorphic xanthoastrocytoma

BackgroundHigh frequencies of the BRAF V600E mutation have been reported in pleomorphic xanthoastrocytoma (PXA). Recently, a BRAF V600E mutation-specific antibody has been developed and validated. We evaluated the immunohistochemical (IHC) detection of BRAF V600E mutation in PXA by comparing to gold standard molecular analysis and investigating the interobserver variability of the IHC scoring. We performed BRAF V600E IHC in 46 cases, of which 37 (80%) cases had sufficient tumor tissue for molecular analysis. IHC detection was performed using monoclonal mouse antibody VE1 (Spring Bioscience). IHC slides were scored independently by four reviewers blind to molecular data, including a primary (gold standard) and three additional reviewers. BRAF V600E mutation status was assessed by allele-specific polymerase chain reaction (PCR) with fragment analysis.ResultsAll 46 cases showed interpretable BRAF V600E IHC results: 27 (59%) were positive (strong cytoplasmic staining), 19 (41%) were negative (6 of these cases with focal/diffuse weak cytoplasmic staining, interpreted as nonspecific by the primary reviewer). By molecular analysis, all 37 cases that could be tested had evaluable results: 22 (59%) cases were positive for BRAF V600E mutation and were scored as “IHC-positive”, and 15 (41%) were negative (including 11 cases scored as “IHC-negative” and 4 cases scored as negative with minimal nonspecific staining). IHC detection of BRAF V600E mutant protein was congruent in all 37 cases that were successfully evaluated by molecular testing (sensitivity and specificity of 100%). Agreement for IHC scoring among the 4 reviewers was almost perfect (kappa 0.92) when cases were scored as “positive/negative” and substantial (kappa 0.78) when minimal nonspecific staining was taken into account.ConclusionsWe conclude that detection of BRAF V600E mutation by immunohistochemistry is highly sensitive and specific. BRAF V600E IHC interpretation is usually straightforward, but awareness of possible nonspecific staining is necessary and training is recommended. It is a practical rapid method that may avoid the need of labor-intensive molecular testing and may be most valuable in small biopsies unsuitable for molecular analysis.

Diagnostic utility of aquaporin-4 in the analysis of active demyelinating lesions

Objective: To assess, in a surgical biopsy cohort of active demyelinating lesions, the diagnostic utility of aquaporin-4 (AQP4) immunohistochemistry in identifying neuromyelitis optica (NMO) or NMO spectrum disorder (NMOSD) and describe pathologic features that should prompt AQP4 immunohistochemical analysis and AQP4–immunoglobulin G (IgG) serologic testing. Methods: This was a neuropathologic cohort study of 20 surgical biopsies (19 patients; 11 cord/9 brain), performed because of diagnostic uncertainty, interpreted as active demyelinating disease and containing 2 or more of the following additional features: tissue vacuolation, granulocytic infiltrates, or astrocyte injury. Results: AQP4 immunoreactivity was lost in 18 biopsies and increased in 2. Immunopathologic features of the AQP4 loss cohort were myelin vacuolation (18), dystrophic astrocytes and granulocytes (17), vascular hyalinization (16), macrophages containing glial fibrillary acid protein (GFAP)–positive debris (14), and Creutzfeldt-Peters cells (0). All 14 cases with available serum tested positive for AQP4-IgG after biopsy. Diagnosis at last follow-up was NMO/NMOSD (15) and longitudinally extensive transverse myelitis (1 each relapsing and single). Immunopathologic features of the AQP4 increased cohort were macrophages containing GFAP-positive debris and granulocytes (2), myelin vacuolation (1), dystrophic astrocytes (1), Creutzfeldt-Peters cells (1), and vascular hyalinization (1). Diagnosis at last follow-up was multiple sclerosis (MS) and both tested AQP4-IgG seronegative after biopsy. Conclusions: AQP4 immunohistochemistry with subsequent AQP4-IgG testing has diagnostic utility in identifying cases of NMO/NMOSD. This study highlights the importance of considering NMOSD in the differential diagnosis of tumefactive brain or spinal cord lesions. AQP4-IgG testing may avert biopsy and avoid ineffective therapies if these patients are erroneously treated for MS.

Comparison of Gadolinium Concentrations within Multiple Rat Organs after Intravenous Administration of Linear versus Macrocyclic Gadolinium Chelates

Purpose To compare gadolinium tissue concentrations of multiple linear and macrocyclic chelates in a rat model to better understand the scope and extent of tissue deposition following multiple intravenous doses of gadolinium-based contrast agent (GBCA). Materials and Methods In this Institutional Animal Care and Use Committee-approved study, healthy rats received 20 intravenous injections of 2.5 mmol gadolinium per kilogram (gadolinium-exposed group) or saline (control group) over a 26-day period. Unenhanced T1 signal intensities of the dentate nucleus were measured from magnetic resonance (MR) images obtained prior to GBCA injection and 3 days after final injection. Rat brain and renal, hepatic, and splenic tissues were harvested 7 days after final injection and subjected to inductively coupled plasma mass spectrometry and transmission electron microscopy for quantification and characterization of gadolinium deposits. Results Gadolinium deposition in brain tissue significantly varied with GBCA type (F = 31.2; P < .0001), with median concentrations of 0 μg gadolinium per gram of tissue (95% confidence interval [CI]: 0, 0.2) in gadoteridol-injected rats, 1.6 μg gadolinium per gram of tissue (95% CI: 0.9, 4.7) in gadobutrol-injected rats, 4.7 μg gadolinium per gram of tissue (95% CI: 3.5, 6.1) in gadobenate dimeglumine-injected rats, and 6.9 μg gadolinium per gram of tissue (95% CI: 6.2, 7.0) in gadodiamide-injected rats; a significant positive dose-signal intensity correlation was identified (ρ = 0.93; P < .0001). No detectable neural tissue deposition or MR imaging signal was observed in control rats (n = 6). Similar relative differences in gadolinium deposition were observed in renal, hepatic, and splenic tissues at much higher tissue concentrations (P < .0001). Gadolinium deposits were visualized directly in the endothelial capillary walls and neural interstitium in GBCA-injected rats, but not in control rats. Conclusion Tissue deposition of gadolinium was two- to fourfold higher following administration of the linear agents gadodiamide and gadobenate dimeglumine compared with the macrocyclic agents gadobutrol and gadoteridol. These findings suggest that organ tissue deposition is reduced but not eliminated following administration of macrocyclic GBCA chelates in lieu of linear chelates.

Intracranial gadolinium deposition following gadodiamide-enhanced magnetic resonance imaging in pediatric patients: A case-control study

Intracranial Gadolinium Deposition Following Gadodiamide-Enhanced Magnetic Resonance Imaging in Pediatric Patients: A Case-Control Study Approximately 40% of the 3 million annual pediatric magnetic resonance imaging (MRI) examinations in the United States are performed with intravenous administration of a gadolinium-based contrast agent (GBCA).1 Contrastenhanced MRI provides critical clinical information that is often not apparent on unenhanced MRI or other imaging modalities. Notwithstanding their widespread use, studies demonstrating the unexpected accumulation of gadolinium within the neural tissues of adults following intravenous GBCA exposure have prompted ongoing investigations by the US Food and Drug Administration and European Medicines Agency regarding the safety and toxicity of these agents.2,3 Because these prior studies were limited to adults, the purpose of this study was to determine the extent of deposition in the GBCA-exposed population and whether prior observations were related to age-dependent breakdown of the blood-brain barrier through study of a cohort of pediatric patients who received gadodiamide-enhanced MRI examinations.

Safety of intrathecal autologous adipose-derived mesenchymal stromal cells in patients with ALS

Objective: To determine the safety of intrathecal autologous adipose-derived mesenchymal stromal cell treatment for amyotrophic lateral sclerosis (ALS). Methods: Participants with ALS were enrolled and treated in this phase I dose-escalation safety trial, ranging from 1 × 107 (single dose) to 1 × 108 cells (2 monthly doses). After intrathecal treatments, participants underwent standardized follow-up, which included clinical examinations, revised ALS Functional Rating Scale (ALSFRS-R) questionnaire, blood and CSF sampling, and MRI of the neuroaxis. Results: Twenty-seven patients with ALS were enrolled and treated in this study. The safety profile was positive, with the most common side effects reported being temporary low back and radicular leg pain at the highest dose level. These clinical findings were associated with elevated CSF protein and nucleated cells with MRI of thickened lumbosacral nerve roots. Autopsies from 4 treated patients did not show evidence of tumor formation. Longitudinal ALSFRS-R questionnaires confirmed continued progression of disease in all treated patients. Conclusions: Intrathecal treatment of autologous adipose-derived mesenchymal stromal cells appears safe at the tested doses in ALS. These results warrant further exploration of efficacy in phase II trials. Classification of evidence: This phase I study provides Class IV evidence that in patient with ALS, intrathecal autologous adipose-derived mesenchymal stromal cell therapy is safe.

Transnasal Odontoid Resection: Is there an Anatomic Explanation for Differing Swallowing Outcomes?

OBJECT Swallowing dysfunction is common following transoral (TO) odontoidectomy. Preliminary experience with newer endoscopic transnasal (TN) approaches suggests that dysphagia may be reduced with this alternative. However, the reasons for this are unclear. The authors hypothesized that the TN approach results in less disruption of the pharyngeal plexus and anatomical structures associated with swallowing. The authors investigate the histological and gross surgical anatomical relationship between pharyngeal plexus innervation of the upper aerodigestive tract and the surgical approaches used (TN and TO). They also review the TN literature to evaluate swallowing outcomes following this approach. METHODS Seven cadaveric specimens were used for histological (n = 3) and gross anatomical (n = 4) examination of the pharyngeal plexus with the TO and TN surgical approaches. Particular attention was given to identifying the location of cranial nerves (CNs) IX and X and the sympathetic chain and their contributions to the pharyngeal plexus. S100 staining was performed to assess for the presence of neural tissue in proximity to the midline, and fiber density counts were performed within 1 cm of midline. The relationship between the pharyngeal plexus, clivus, and upper cervical spine (C1-3) was defined. RESULTS Histological analysis revealed the presence of pharyngeal plexus fibers in the midline and a significant reduction in paramedian fiber density from C-2 to the lower clivus (p < 0.001). None of these paramedian fibers, however, could be visualized with gross inspection or layer-by-layer dissection. Laterally based primary pharyngeal plexus nerves were identified by tracing their origins from CNs IX and X and the sympathetic chain at the skull base and following them to the pharyngeal musculature. In addition, the authors found 15 studies presenting 52 patients undergoing TN odontoidectomy. Of these patients, only 48 had been swallowing preoperatively. When looking only at this population, 83% (40 of 48) were swallowing by Day 3 and 92% (44 of 48) were swallowing by Day 7. CONCLUSIONS Despite the midline approach, both TO and TN approaches may injure a portion of the pharyngeal plexus. By limiting the TN incision to above the palatal plane, the surgeon avoids the high-density neural plexus found in the oropharyngeal wall and limits injury to oropharyngeal musculature involved in swallowing. This may explain the decreased incidence of postoperative dysphagia seen in TN approaches. However, further clinical investigation is warranted.

Chronic meralgia paresthetica and neurectomy: a clinical pathologic study.

Objective: To understand the pathologic and clinical correlates of patients with chronic meralgia paresthetica (MP) undergoing lateral femoral cutaneous nerve (LFCN) neurectomy. Methods: A retrospective cohort approach was utilized to identify 7 patients undergoing LFCN neurectomy for intractable pain. Control autopsied LFCN was obtained. Clinical, radiologic, and electrophysiologic features were reviewed. Results: In identified cases, preoperative symptoms included severe lateral thigh pain and numbness. The duration of symptoms prior to surgery ranged from 2 to 15 years. Body mass index (BMI) varied from 20 kg/m2 to 44.8 kg/m2 (normal–morbidly obese), with 6 out of 7 patients being obese. No patients were diabetic. Focal nerve indentation at the inguinal ligament was seen intraoperatively and on gross pathology in 4 of 7 cases. Multifocal fiber loss, selective loss of large myelinated fibers, thinly myelinated profiles, regenerating nerve clusters, perineurial thickening, and subperineurial edema were seen. None of these features were observed in control nerve. Morphometric analysis confirmed loss of large myelinated fibers with small and intermediate size fiber predominance. Five patients had varying degrees of intraneural and epineurial inflammation. Six of 7 reported improved pain after neurectomy, sometimes dramatic. Conclusions: Patients with chronic MP and intractable pain have an LFCN mononeuropathy with loss of nerve fibers. Pathologic and clinical study supports a compressive pathogenesis as the primary mechanism. Abnormal nerve inflammation coexists and may play a role in pathogenesis. These selected patients typically benefited from neurectomy at a site of inguinal ligament compression. Classification of Evidence: This study provides Class IV evidence that patients with chronic MP LFCN neurectomy experience improvement in MP-related pain.

Magnetic resonance imaging evidence for perineural spread of endometriosis to the lumbosacral plexus: report of 2 cases

Sciatic nerve endometriosis (EM) is a rare presentation of retroperitoneal EM. The authors present 2 cases of catamenial sciatica diagnosed as sciatic nerve EM. They propose that both cases can be explained by perineural spread of EM from the uterus to the sacral plexus along the pelvic autonomie nerves and then further distally to the sciatic nerve or proximally to the spinal nerves. This explanation is supported by MRI evidence in both cases. As a proof of concept, the authors retrieved and analyzed the original MRI studies of a case reported in the literature and found a similar pattern of spread. They believe that the imaging evidence of their institutional cases together with the outside case is a very compelling indication for perineural spread as a mechanism of EM of the nerve.