Neurovascular relationship at the trigeminal root entry zone in persistent idiopathic facial pain: findings from MRI 3D visualisation.

BACKGROUND: Patients with atypical neuralgia or atypical facial pain have been surgically treated with microvascular decompression (MVD) of the trigeminal root entry zone (TREZ). There are no data regarding the sensitivity and specificity of a vessel-TREZ relationship as a cause of pain in patients with persistent idiopathic facial pain (PIFP) according to the definition given by the International Headache Society (IHS). METHODS: The TREZ was visualised by 3D CISS MRI in 12 patients with unilateral PIFP according to the IHS criteria. RESULTS: The frequency of artery-TREZ, vein-TREZ, or vessel (artery/vein)-TREZ contacts on the symptomatic and asymptomatic sides did not differ significantly. On the symptomatic side, vessel-TREZ contact was found in 58% of patients (sensitivity). On the asymptomatic side, vessel-TREZ contact was absent in 33% of patients (specificity). CONCLUSIONS: On the basis of the low sensitivity and specificity found in the present study, PIFP cannot be attributed to a vessel-TREZ contact, and therefore, pain relief after MVD cannot be expected.

Cortical T2 signal shortening in amyotrophic lateral sclerosis is not due to iron deposits.

Signal shortening of the motor cortex in T2-weighted MR images is a frequent finding in patients with amyotrophic lateral sclerosis (ALS). The cause of signal shortening in ALS is unknown, although iron deposits have been suggested. To test this hypothesis, we acquired T2*-weighted gradient-echo (GRE) MR images in addition to T2-weighted turbo spin-echo in 69 patients with ALS. Signal shortening in T2-weighted images was found in 31 patients. In T2*-weighted GRE images, only three patients had signal shortening. One patient with additional bifrontal haemorrhage had frontal but no motor cortex signal shortening. Iron deposits do not cause cortical signal shortening in patients with ALS predominantly. Other factors are presumably more important in the generation of cortical T2 shortening in ALS.

Iatrogenic (para-) spinal abscesses and meningitis following injection therapy for low back pain.

Low back pain is often treated with paraspinal injections of analgesics and steroids. Infectious complications of these techniques are rare but they can potentially hold high risks for the patients. History and clinical data of all patients admitted to a neurological unit suffering from community acquired purulent meningitis were prospectively analyzed during an 8 year interval (1992 and 2000) with special regard to the previous medical history. One hundred and twenty eight patients were included in the study. Eight out of 128 patients (6.25%) had a history of single or repeated paravertebral (4/8), facet-joint (2/8), peridural (1/8) or spinal (1/8) injections 2-21 days before admission to the hospital. In six out of eight patients either Staphylococcus aureus (4/8) or coagulase-negative staphylococci (2/8) were found in the cerebro spinal fluid (CSF), in two patients no causative organism was detected. One patient died, three survived with sequel. Repeated paraspinal, peridural or spinal injections with analgesic drugs in combination with corticosteroids hold a risk for parameningeal inoculation of bacteria resulting in paraspinal, spinal, and epidural abscesses or meningitis. The absolute frequency of these complications may be rare but they are responsible for a considerable proportion of community acquired purulent CNS infections.

The AGE/RAGE/NF-(kappa)B pathway may contribute to the pathogenesis of polyneuropathy in impaired glucose tolerance (IGT).

Binding of ligands to the receptor for advanced glycation end products (RAGE) results in activation of the transcription factor nuclear factor kappa B (NF-(kappa)B) and subsequent expression of NF-(kappa)B-regulated cytokines. This has been shown to be a relevant pathomechanism in diabetic polyneuropathies (PNP). To determine whether this pathway may contribute to the pathogenesis of PNP due to impaired glucose tolerance (IGT) we performed a pilot study to demonstrate the presence of the RAGE ligand N (epsilon)-(Carboxymethyl)lysine (CML), the receptor itself and N-(kappa)B in sural nerve biopsies of 4 patients with IGT-related PNP. Biopsies of either 4 patients with diabetic PNP and with Charcot-Marie-Tooth disease (CMT) I and II served as positive and negative controls, respectively. In IGT-related PNP and diabetic PNP, CML, RAGE, and NF-(kappa)B was found in the perineurium, epineurial vessels and in part in endoneurial vessels. CMT patients showed, if any, only weak staining for one or the other antigen. These data suggest that activation of the RAGE pathway may be one of the first steps in the pathogenesis of PNP even before chronic hyperglycemia occurs.

The RAGE pathway in inflammatory myopathies and limb girdle muscular dystrophy.

Oxidative stress and nuclear factor-kappaB (NF-kappaB) activation are linked to the pathogenesis of many metabolic, degenerative, and chronic inflammatory diseases. Activation of the receptor for advanced glycation end products (RAGE) by its specific ligand N(epsilon)-carboxymethyllysine (CML) results in the activation of NF-kappaB and the production of proinflammatory cytokines. To determine whether engagement of RAGE contributes to the pathogenesis of inflammatory myopathies, we performed immunohistochemical studies on the presence of CML-modified proteins, RAGE and activated NF-kappaB in muscle biopsies of patients with polymyositis (PM, n=10), dermatomyositis (DM, n=10), limb girdle muscular dystrophy (LGMD, n=10) and in 10 controls with normal muscle biopsy results. In inflammatory myopathies CML, RAGE and NF-kappaB were detected in mononuclear cells and in regenerating muscle fibers. CML, NF-kappaB and, to a lesser extent, RAGE were also found in degenerating muscle fibers, but colocalization of CML, RAGE and NF-kappaB was only seen in infiltrating mononuclear cells and regenerating muscle fibers. Immunofluorescence double labeling demonstrated an expression of CML, RAGE and NF-kappaB in CD4-, CD8-, CD22- and CD68-positive mononuclear cells. Western blot analysis showed an increased immunoreactivity for CML-modified proteins in PM and DM. In LGMD, CML, RAGE and NF-kappaB were found in regenerating muscle fibers and less frequently in degenerating muscle fibers, and with lower staining intensities than in inflammatory myopathies. Our data suggests that the CML-RAGE-NF-kappaB pathway is an evident proinflammatory pathomechanism in mononuclear effector cells in PM and DM. RAGE-mediated NF-kappaB activation may be involved in muscle fiber regeneration in inflammatory myopathies and LGMD.

Short TE single-voxel 1H-MR spectroscopy of hippocampal structures in healthy adults at 1.5 Tesla--how reproducible are the results?

The purpose of our study was to evaluate inter- and intra-subject variability and scan-rescan reproducibility of single-voxel 1H-MR spectroscopy (1H-MRS) in hippocampal structures at 1.5 T field strength. Thirty healthy adults were studied bilaterally by optimized, standardized short echo time single-voxel 1H-MRS (PRESS, TE=30 ms, TR=3000 ms, oblique voxel orientation, voxel size 2 cm3). Spectral analysis and absolute metabolite quantitation of N-acetylaspartate+N-acetylaspartyl-glutamate (tNAA), choline (Cho), creatine (Cr), total glutamate plus glutamine (Glu+Gln) and myo-inositol (Ins) were carried out by LCModel. Inter- and intra-individual reproducibility of these metabolite values were investigated by calculation of mean, standard deviation, coefficient of variation (CV), and by analysis of variance for repeated measurements. The smallest CV in intersubject variability was obtained for tNAA, followed by Cr, Cho, Ins and Glu+Gln. The results of the analysis of variance for repeated measures in inter-subject variability showed a marginal effect of scan repetition for Cr (p=0.063) and Glu+Gln (p=0.082); the rescan of both metabolites showed slightly higher concentrations. No statistical significant effect of scan repetition was seen for tNAA (p=0.913), Cho (p=0.857), and Ins (p=0.826). Rescan led to the same results and gave proof of good reproducibility. Scan-rescan testing in one subject showed comparable results: tNAA (CV=4.8%), followed by Cr, Ins, Glu+Gln and Cho (all CV above 10%).