Changes In Nerve Roots Research Articles

Diffusion-Weighted MR Neurography with Unidirectional Motion-Probing Gradient to Evaluate Lumbar Nerve Roots at 1.5T MR.

Recent studies have demonstrated the usefulness of diffusion-weighted MR neurography (DW MRN) for assessing nerve roots. This study aimed to evaluate the utility of DW MRN with a unidirectional motion-probing gradient (MPG) for the lumbar nerve roots at 1.5T MR. Sixty-four lumbar spine MRI scans with DW MRN using anteroposterior unidirectional MPG were retrospectively analyzed. Any changes in the 512 lumbar spinal nerve roots from L3 to S1 were evaluated using T2-weighted imaging (T2WI), contrast-enhanced T1-weighted imaging (CE T1WI), and DW MRN, with agreement and correlation analysis. T2WI revealed compression of 78 nerve roots, and CE T1WI revealed 52 instances of nerve root enhancement. Sixty-seven nerve roots showed swelling and hyperintensity on DW MRN. A total of 42 nerve roots showed changes in the CE T1WI and DW MRN sequences. Moderate to substantial agreement and moderate positive correlation were observed between DW MRN and CE T1WI, as well as DW MRN and T2WI (κ = 0.59-0.65, ρ = 0.600-0.653). DW MRN with unidirectional anteroposterior MPG can help evaluate neuritis-related changes in spinal nerve roots and could serve as a sequence capable of complementing or substituting gadolinium CE imaging.

An Ultrasonographic Evaluation for the Early Detection of Nerve Root Changes in Herpes Zoster-associated Motor Paresis.

We herein report a case of herpes zoster complicated by right-arm paralysis, wherein cervical nerve root ultrasonography enabled the early diagnosis and a therapeutic efficacy evaluation. A 71-year-old man developed progressive weakness in the muscles innervated by the right C5-6 nerve root following the appearance of a painful rash. Cervical nerve root ultrasonography revealed C5-6 nerve root inflammatory swelling. Methylprednisolone pulse therapy and subsequent oral prednisolone therapy gradually improved the muscle weakness. At three weeks following admission, ultrasonography revealed C5-6 nerve root inflammatory swelling improvement. Ultrasonography may aid in the early detection of nerve root inflammatory swelling and help monitor treatment efficacy.

Fast Independent Component Analysis Algorithm-Based Diagnosis of L5 Nerve Root Compression and Changes of Brain Functional Areas Using 3D Functional Magnetic Resonance Imaging.

In this paper, the application of 3-dimensional (3D) functional magnetic resonance imaging (FMRI) in the diagnosis of the 5th lumbar (L5) nerve root compression and brain functional areas in patients with lumbar disc herniation (LDH) was analyzed. The traditional fast independent component analysis (Fast ICA) algorithm was optimized based on the modified whitening matrix to establish a new type of Modified-Fast ICA (M-Fast ICA) algorithm that was compared with the introduced traditional Fast ICA and ICA. M-Fast ICA was applied to the 3D FMRI diffusion tensor imaging (DTI) evaluation of 65 patients with L5 nerve root pain due to LDH (group A) and 50 healthy volunteers (group B). The values of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in the lumbar nerve roots (L3, L4, L5, and the 1st sacral vertebra (S1)) were recorded among subjects from the two groups. Besides, the score of edema degree in the lumbar nerve roots (L5 and S1) and activity of brain functional areas were also recorded among all subjects of the two groups. The results showed that the mean square error of M-Fast ICA was smaller than that of traditional Fast ICA and ICA, while its signal-to-noise ratio (SNR) was greater than that of Fast ICA and ICA (P < 0.05). The FA of L5 and S1 nerve roots in patients of group A was sharply lower than the values of group B, while the ADC of patients in group A was greater than that of the control group (P < 0.05). Besides, the score of edema in L5 and S1 nerve roots of patients in group A increased in contrast to group B (P < 0.05). The brain areas were activated after surgery including bilateral temporal lobe, left thalamus, splenium of corpus callosum, and right internal capsule. In conclusion, the 3D image denoising performance of M-Fast ICA optimized and constructed in this study was superior to that of the traditional Fast ICA and ICA. The FA of patients with L5 nerve root pain due to LDH decreased steeply, while the ADC increased dramatically. L5 nerve root pain caused by LDH resulted in changes in brain functional areas of the patients to inhibit the resting state default network activity, and the corresponding brain functional areas could be activated through treatment.

Evaluation of L7-S1 nerve root pathology with low-field MRI in dogs with lumbosacral foraminal stenosis.

To describe low-field MRI findings associated with lumbosacral foraminal stenosis and radiculopathy and correlate these with clinical signs. Retrospective study. Client-owned dogs (n = 240) that underwent a clinical examination and standardized MRI protocol of the lumbosacral junction. Medical records of dogs with degenerative lumbosacral stenosis with neurological clinical evaluation and MRI of the lumbosacral junction were used to describe imaging pathologies and relate them to clinical status. In total, 480 L7 neuroforamina were evaluated. A loss of foraminal fat signal was identified in 364 of 480 neuroforamina of which 87.9% (n=320) showed also concurrent nerve root changes. Magnetic resonance imaging features of L7 radiculopathy included nerve root enlargement and hyperintensity to surrounding connective tissue in dorsal oblique gradient echo short time inversion recovery sequences and specific changes in shape, size, or position of the nerve root in transverse T1-weighted sequences. Radiculopathy was noted as a consequence of either circumferential (entrapment) or focal (impingement) foraminal stenosis. Lateral vertebral spondylotic and intervertebral facet joint changes were the most common underlying spinal and neuroforaminal pathologies. Clinical signs were present in the ipsilateral hind leg in 85% (n = 65) of dogs with unilateral lumbosacral imaging findings. A loss of foraminal fat signal was likely to be associated with L7 radiculopathy and foraminal stenosis. Unilateral lesions were generally associated with clinical signs on the ipsilateral limb. Loss of foraminal fat signal revealed by low-field MRI should prompt the assessment of concurrent radiculopathy and underlying stenosis, and in coherence with clinical findings, when is combined with clinical findings, improves the diagnosis of lumbosacral foraminal stenosis.

The phenotypic morphology of human lumbar plexus roots associated with changes in the thoracolumbar vertebral count and trade-off

This study investigated the developmental basis for the human phenotypic morphology of the interaction between the vertebrae and the nerve plexus by evaluating changes in the human lumbar plexus according to various thoracolumbar formulas. The dissection found that the changes in lumbar nerve roots reported by experimental embryology studies to be concomitant with thoracolumbar trade-off, i.e., a change in vertebrae from thoracic to lumbar with no change in the overall thoracolumbar count, were not apparent in humans with the usual 17 or mutant 16 thoracolumbar vertebrae. When vertebral changes in two segments were examined by comparing spines with a reduced thoracolumbar count of 16 to those with an increased count of 18, this tended to show only a single-segment caudal shift of the lumbar plexus. We cannot provide evidence for the phylogenetic difference in the concomitant changes of lumbar nerves and vertebrae, but comparisons between experimental rodents and humans highlighted fewer and shorter lumbar vertebra and more complicated lumbar plexus in humans. Therefore, these multiple differences may contribute to a human phenotypic morphology that is not evident in the concomitant transformation of vertebrae and lumbar nerves reported in experimental rodents.

DIFFUSION-TENSOR MRI IN TRIGEMINAL NEURALGIA CAUSED BY NEUROVASCULAR CONFLICT

Diffusion-tensor imaging in modern MR units is perspective tool for creation of tracts of brain white matter. Most often reason for trigeminal neuralgia (TN) is vascular compression. Very important part in pain pathogenesis is played by structural changes, due to demyelination of trigeminal nerve root, caused by compression. Studying of structural changes of trigeminal nerve root in trigeminal neuralgia with DTI could clear influence of vascular compression for development of TN. The aim of this study was to estimate fractional anisotropy changes in trigeminal nerve root. Study included 33 patients with TN, who underwent microvascular decompression. Some of patients also had manipulation on trigeminal nerve root in anamnesis. It was revealed that fractional anisotropy (FA) is linked with compression degree and TN type — the less FA the higher the degree. After estimation of DTI it was revealed that FA is the less when patient had on trigeminal nerve root in anamnesis. Obtained data show changes that DTI could be helpful in choice of treatment tactics, allowing to demonstrate link of trigeminal root changes with compression.

Microstructural changes in compressed nerve roots treated by percutaneous transforaminal endoscopic discectomy in patients with lumbar disc herniation.

To investigate the microstructural changes in compressed nerves using diffusion tensor imaging (DTI) of herniated disc treated with percutaneous transforaminal endoscopic discectomy.Diffusion tensor imaging has been widely used to visualize peripheral nerves, and the microstructure of compressed nerve roots can be assessed using DTI. However, the microstructural changes after surgery are not well-understood in patients with lumbar disc herniation.Thirty-four consecutive patients with foraminal disc herniation affecting unilateral sacral 1 (S1) nerve roots were enrolled in this study. DTI with tractography was performed on S1 nerve roots before and after surgery. The mean fractional anisotropy (FA) and apparent diffusion coefficient values were calculated from tractography images.In compressed nerve roots, the FA value before surgery was significantly lower than that after surgery (P = 0.000). A significant difference in FA values was found between the compressed and normal sides before surgery (P = 0.000). However, no significant difference was found between the compressed and normal sides after surgery (P = 0.057). A significant difference in apparent diffusion coefficient values was found before and after surgery at the compressed side (P = 0.023). However, no significant difference was found between the compressed and normal sides after surgery (P = 0.203).We show that the diffusion parameters of compressed nerve roots were not significantly different before and after percutaneous transforaminal endoscopic discectomy, indicating that the microstructure of the nerve root recovered after surgery.

Changes in lumbosacral spinal nerve roots on diffusion tensor imaging in spinal stenosis.

Lumbosacral degenerative disc disease is a common cause of lower back and leg pain. Conventional T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI) scans are commonly used to image spinal cord degeneration. However, these modalities are unable to image the entire lumbosacral spinal nerve roots. Thus, in the present study, we assessed the potential of diffusion tensor imaging (DTI) for quantitative assessment of compressed lumbosacral spinal nerve roots. Subjects were 20 young healthy volunteers and 31 patients with lumbosacral stenosis. T2WI showed that the residual dural sac area was less than two-thirds that of the corresponding normal area in patients from L3 to S1 stenosis. On T1WI and T2WI, 74 lumbosacral spinal nerve roots from 31 patients showed compression changes. DTI showed thinning and distortion in 36 lumbosacral spinal nerve roots (49%) and abruption in 17 lumbosacral spinal nerve roots (23%). Moreover, fractional anisotropy values were reduced in the lumbosacral spinal nerve roots of patients with lumbosacral stenosis. These findings suggest that DTI can objectively and quantitatively evaluate the severity of lumbosacral spinal nerve root compression.

A rat model for chronic spinal nerve root compression

The pathophysiology of radiculopathy associated with lumbar spinal stenosis and lumbar disc herniation is incompletely understood. The goal of the present study was to establish a chronic spinal nerve root compression model that can mimic lumbar disc herniation or spinal stenosis using silicone tube compression. We also try to link the pathology changes of damaged nerve root with the reaction of microglia in spinal cord in same rat at different time points. Thirty rats were used in this study. The L5 nerve roots (dorsal and ventral) were exposed by hemilaminectomy; the diameter of the L5 nerve root was measured at the 2mm proximal from the dorsal root ganglia. The dorsal and ventral nerve roots of L5 were compressed using a silicone tube, and the sham group was only exposed dorsal and ventral roots of L5. Five rats from the sham group were perfused at 8days after surgery, and 25 rats from the model groups were perfused at 3, 8, 12, 45days, and 5months after surgery, each model group was composed of 5 rats according to the time point. The L5 spinal cord segments and nerve root that compressed by silicone tube were harvested from the same rat. Microglia and neuron in the spinal cord were stained by immunohistochemistry, and the nerve root was shown by electron microscope. In sham-operated rat, the arrangement of axon and myelin sheath is normal, the ventral root is mainly composed of large axon (>6μm) and it is composed of 46.3% of all the axons of the ventral root; the average myelin thickness of large axon is 1.86μm; the dorsal root is mainly composed of medium (2-3.9 or 4-5.9μm) axons and they are composed of 79.1% of all the axons of the dorsal root; the average myelin thickness of this category is 0.94 or 1.55μm. The average myelin thickness of large axon in ventral root reduced to 0.97 and 1.19μm from more than 1.86μm after compression for 3 and 8days separately. Most of myelin sheath disappeared after 12days of compression; the myelin sheath was partly restored at 45days after compression which the myelin sheath thickness of large axons in ventral root was 0.47μm. The medium category in dorsal root reduced to 0.59 or 0.72μm from 0.94μm, and 1.55μm after compression for 3days (p<0.05 to p<0.0001). The medium category axon in dorsal root is also 0.47μm after compression for 45days (p≤0.0001). The myelin sheath was almost totally restored at the 5months of compression; the myelin sheath thickness returned to normal and the axons were intact in structure under EM. The number of Iba1-positive microglia increased by 18.69, 40.44, and 18.49% after compression for 3, 8, and 12days separately in the ipsilateral dorsal horn and 21.26, 32.15, 22.87% in ventral horns, and the activation of microglia was also prominent in contralateral sides of the dorsal and ventral horn at 8days time point. The microglia cell reconverted to resting status after compression for 45days or 5months. The chronic spinal nerve root compression with silicone tube produces a recoverable damage to nerve root, which produces recoverable microglial activation in the spinal cord. These results demonstrated that the chronic spinal nerve root compression with silicone tube could mimic the pathological changes of lumbar spinal stenosis or lumbar disc herniation.

A CASE OF ‘PING–PONG’ GAZE OF UNKNOWN CAUSE

A 66 year-old Indian gentleman with a background of type II diabetes, Crohn's disease and previously treated tuberculosis presented with double vision and unsteadiness.He was found to have a right-sided...

Bickerstaff’s Brainstem Encephalitis Presenting to the ICU

Bickerstaff's brainstem encephalitis continues to pose a diagnostic and treatment challenge since the original descriptions by Bickerstaff and Miller-Fisher. The clinical syndrome overlaps with AIDP and MFS, but is accompanied by decreased level of consciousness not attributable to other causes, and the variable presence of long-tract signs. The methods in this study include the case presentation with autopsy findings of an elderly male presented with progressive weakness and impairment of consciousness and the literature review. Examination revealed areflexia and loss of most brainstem reflexes. Some improvement occurred after several weeks in the ICU, prior to death from pulmonary embolism. Pathologic specimens were similar to others in the literature, with inflammatory changes in nerve roots and brainstem. The above findings led us to conclude that Bickerstaff's brainstem encephalitis remains a clinical diagnosis despite advances in electrophysiologic testing and neuroimaging. BBE likely represents part of a spectrum, overlapping with AIDP and MFS. Immunomodulation may be helpful in shortening the clinical course.

Three-Dimensional Magnetic Resonance Rendering Imaging of Lumbosacral Radiculography in the Diagnosis of Symptomatic Extraforaminal Disc Herniation With or Without Foraminal Extension

Retrospective analysis of lumbosacral radiculography using 3-dimensional (3D) magnetic resonance (MR) rendering in patients with extraforaminal disc herniation. To investigate the significance of lumbosacral radiculography as depicted by 3D MR rendering in the diagnosis of symptomatic extraforaminal disc herniation with or without foraminal extension. Given that accurate evaluation of the extraforaminal zones on routine axial and sagittal images is difficult, extraforaminal disc herniations tend to be sometimes overlooked. In addition, oblique coronal images along intervertebral foramina and MR myelography may not clearly demonstrate a detailed full view of nerve root changes. Furthermore, the detection of the morphologic changes of the nerve root is very important for the diagnosis of symptomatic extraforaminal disc herniation. Thus, a useful method for evaluating the nerve root in order to diagnose symptomatic extraforaminal disc herniation is required. Twenty-four patients with extraforaminal and combined (extraforaminal with foraminal) lumbar disc herniations were included in this study. Conventional spin-echo sequence and 3D coronal fast-field echo sequences with selective water excitation by using the principles of the selective excitation technique (Proset imaging) were acquired. Indentation and swelling of the nerve roots and dorsal root ganglion (DRG) in the symptomatic sides and levels were evaluated on the basis of 3D MR rendering images of the lumbar spine. The tilting angle of the nerve root in the symptomatic side was compared with those in the asymptomatic contralateral side again on the basis of the 3D MR rendering images. Dorsal root ganglion indentation without swelling of the nerve roots was found in 7 patients whereas that with swelling of the nerve roots was observed in 6 patients. Swelling of the entire segment of the nerve from nerve root to spinal nerve (n = 9) or only the spinal nerve (n = 2) was observed in 11 patients. Compared with the contralateral nerve root, 7 patients exhibited a tilting angle abnormality of the ipsilateral nerve root. Based on lumbosacral radiculography through 3D MR rendering, important findings related to the diagnosis of symptomatic extraforaminal disc herniation include swelling of DRG and/or nerve roots and DRG indentation. Ultimately, 3D MR lumbosacral radiculography is a very useful method in the diagnosis of the symptomatic extraforaminal disc herniation.

Structural and Functional Changes in Nerve Roots Due to Tension at Various Strains and Strain Rates: An In-Vivo Study

This study investigates the functional and structural responses of spinal nerve roots in vivo to various strains and strain rates. Seventy-two L5 dorsal nerve roots from male Sprague-Dawley rats were each subjected to a predetermined strain (<10%, 10-20%, and >20%; n = 8) and rate (0.01 mm/sec, 1 mm/sec, or 15 mm/sec; n = 24). Neurophysiologic recordings were performed before and after stretch to determine changes in conduction velocity (CV), amplitude, and area of the compound action potential (CAP). Morphological injury as evident by primary and secondary axotomy as well as impaired axoplasmic transport (IAT) was determined using the palmgren silver impregnation technique and betaAPP immunostaining, respectively. The results from neurophysiologic recordings indicate that as strain and rate increased, there was a decrease in CV, amplitude, and area of the CAP. Further, high strains led to a complete conduction block that appeared to be rate dependent. Strains of 16%, 10%, and 9%, at 0.01 mm/sec, 1 mm/sec, and 15 mm/sec, respectively, led to 50% probability of complete conduction block in the nerve roots. Results from histological assessment indicate an increase in periaxonal spacing (secondary axotomy) and torn fibers (primary axotomy), as well as impaired IAT, with increasing strain and rate. Overall, the results from the current study indicate that (1) functional nerve root injuries as evident by changes in the CV, amplitude, and area of the CAP are strain- and rate-dependent; (2) high strains at low rates cause complete conduction block in the roots, while a similar block was observed at lower strains at the high rate; (3) the extent of IAT and primary and secondary axotomy occurred concomitant with functional injury and were strain- and rate-dependent.

Symptomatic Nerve Root Changes on Contrast-Enhanced MR Imaging after Surgery for Lumbar Disk Herniation

The significance of postoperative nerve root changes (enhancement, thickening, and displacement) is still a topic of debate. The purpose of this study was to evaluate the association between nerve root changes and residual or recurrent symptoms after lumbar surgery with contrast-enhanced MR imaging. A total of 120 patients with 140 postoperative lumbar disk lesions causing residual or recurrent pain underwent contrast-enhanced MR imaging. The levels at which diskectomies had been performed were retrospectively evaluated for nerve root enhancement (NRE), thickening, and displacement. Association between nerve root changes and corresponding clinical presentations were statistically assessed. Nerve root changes in recurrent disk herniation (RDH) and postoperative epidural fibrosis (PEF) were also evaluated with clinical symptoms. Ninety-two (65.7%) of the 140 disks demonstrated NRE. Regarding the association with clinical symptoms, the sensitivity was 91.7%, the specificity was 73.2%, the positive predictive value (PPV) was 83.7%, and the negative predictive value was 85.4% (P = .000). Nerve root thickening and displacement were significantly associated with the clinical symptoms, especially when NRE was combined (PPV, 87.7% and 87.2%, respectively). When RDH was combined with all 3 nerve root changes, the PPV was increased up to 94.1%. However, in PEF, the association between nerve root changes and clinical symptoms was not significant unless all 3 nerve root changes were combined. In patients with residual or recurrent pain after surgery for lumbar disk herniation, nerve root changes on contrast-enhanced MR imaging were well associated with clinical symptoms, of which NRE was the most significant finding.

The Intrasacral Meningocele

Meningeal diverticula arising as a protrusion of the arachnoid through a weak place in the dura are called sacral meningoceles. They occur in the sacral region and produce local vertebral erosions. Eleven cases of this rare and potentially progressive lesion were detected on 3250 CT examinations of the lumbosacral spine. The pathogenesis and clinical picture of the condition are reviewed. Intrasacral meningoceles are well displayed on CT and MRI scans, although the diagnosis may also be established at myelography. Such arachnoid cysts should be distinguished from lumbosacral dural anomalies observed in von Recklinghausen neurofibromatosis. Surgical excision should be carried out before irreversible nerve root changes occur.

Pathomechanisms of nerve root injury caused by disc herniation: an experimental study of mechanical compression and chemical irritation.

An electrophysiologic and histologic study on nerve roots after mechanical compression and/or local application of nucleus pulposus (NP) was performed. To assess the effects of mechanical compression and/or chemical irritation caused by NP. It has been shown that application of NP to nerve roots without compression induces histologic and functional changes in nerve roots and the dorsal root ganglia. In clinical situations, however, mechanical compression has also been considered an important factor in disc herniation. Eighteen dogs (9-15 kg) were used in this study. Four groups were used to assess the effect of each factor: 1) sham group (n = 3); 2) NP group (NP applied under the S1 lamina) (n = 5); 3) comp group (a plastic balloon placed under the S1 lamina) (n = 5); and 4) comp+NP group (a balloon and NP placed under the S1 lamina) (n = 5). Ascending cauda equina action potentials (CEAPs) and cauda equina-sensory nerve conduction velocity (SCV) were recorded before, immediately after, and 1 week after treatment. Histologic changes were also assessed by light microscopy. There were no significant differences in CEAP and SCV among the four groups immediately after the treatment. However, 1 week after treatment, the amplitudes in the NP group, comp group, and comp+NP group were statistically significantly lower compared with those in the sham group. The comp+NP group showed significantly lower amplitude than did the NP group and comp group. Immediately after treatment, SCV in the NP group and comp group did not show significant differences compared with that in the sham group. However, 1 week after treatment, SCV in the comp+NP group was significantly lower compared with that in the sham group. Histologic changes such as intraneural edema, Schwann cell edema, and nerve fiber injury seemed to be more pronounced in the comp+NP group than in the other groups. It was shown that each of the assessed factors induces nerve dysfunction. However, the combination of mechanical compression (mass effect of herniated NP) and chemical irritation (inflammation around nerve root) may induce more nerve root injury than each factor per se.

Bismuth-induced neuronal cell death in rat dorsal root ganglion: a stereological study.

The goal of the present study has been to quantify the morphological changes in myelinated nerve roots and dorsal root ganglion (DRG) cells in rats exposed to bismuth subnitrate. Male Wistar rats (n =30) were divided into three groups of ten animals. The ten animals in each group were given intraperitoneal injections of one of the following: (1) 500 mg/kg bismuth subnitrate, (2) 1,000 mg/kg bismuth subnitrate, or (3) saline. The mean total cell number of B-cells in the DRG was significantly smaller in the two treated groups, 18% (2P <0.001) and 23% (2P <0.001), respectively, than it was in the control group. In addition, there was an 11% reduction in the number of A-cells (2P =0.039) in rats exposed to the highest concentration of bismuth. Bismuth did not affect the total number or mean cross sectional area of axons and myelin sheaths of the myelinated nerve fibers in the ventral or dorsal nerve root of the DRG. This is the first study to investigate pathological changes of the peripheral nervous system after bismuth intoxication.

Nerve vasculature changes induced by serotonin under chronic cauda equina compression.

An analysis of nerve vascular changes in nerve roots induced by serotonin in chronically compressed nerve roots. To assess the hypotheses that serotonin might have a vasoconstrictive effect in chronically compressed nerve roots. The 5-hydroxytryptamine 2A receptor is involved in serotonin-induced activation or sensitization of sensory nerve terminals. Serotonin exerts complex effects on pain and hyperalgesia through various receptor subtypes located at various levels of the pain transmission system. Serotonin induces endothelium-dependent contraction in vascular diseases. However, there is no knowledge regarding a response of nerve vasculature induced by serotonin in chronically compressed nerve roots. A total of 45 dogs were used. A plastic balloon was placed under the lamina L7 and inflated to 10 mm Hg and left for 1 week. Four experimental groups were used: no operation (Group A, n = 15), the balloon was placed under the lamina but not inflated (Group B, n = 10), the balloon was inflated to 10 mm Hg for 1 week and the pressure was released just before the measurement (Group C, n = 10), and the balloon was inflated to 10 mm Hg for 1 week and inflation was maintained during the measurements (Group D, n = 10). The blood vessels of the second or third sacral nerve were defined after an intra-arterial injection of 0.5 micromol/L or 1.0 micromol/L serotonin using a specially designed operation microscope equipped with a video camera. In all groups 0.5 micromol/L serotonin (each group, n = 5) or 1.0 micromol/L serotonin (each group, n = 5) was injected. In Group A (n = 5) saline was injected. The measurements of diameter of observed blood vessels and blood flow index were performed on video recordings. All statistical assessments were performed by Wilcoxon signed-ranks test and Fisher's PLSD. In Group A, the diameter of blood vessels and blood flow did not change after administration of saline. In the noncompression groups (Groups A and B) the diameter of blood vessels and blood flow increased after injection of 0.5 micromol/L serotonin. In compression groups (Groups C and D) the blood vessels contracted after injecting 0.5 micromol/L serotonin and blood flow decreased. There was a significant difference in the diameter of blood vessels and blood flow between noncompression and compression groups (P < 0.01). There was no difference regarding diameter of blood vessels between released compression (Group C) and maintained compression during measurement group (Group D). In all groups blood vessels contracted and blood flow decreased after injecting 1.0 micromol/L. In electron microscopic observation tight junction of endothelial cells was destroyed in chronically compression nerve roots. The present study demonstrated that serotonin had a vasodilative effect on the intact nerve roots, whereas there was a vasoconstrictive effect to the chronically compressed nerve roots. There was no difference in the diameter of blood vessels between released compression and maintained compression during measurement group. Results suggested that dysfunction of endothelial cells induced by serotonin rather than mechanical compression itself might lead to contraction of blood vessels under chronic compression. Serotonin had a vasoconstrictive effect on the chronically compressed nerve roots.

LUMBAR HERNIATED DISKS

Patients with low back and leg pain require careful evaluation and it is essential that there is correlation between the symptoms and signs of sciatica and the imaging demonstration of nerve root compression or displacement by a disk herniation before invasive therapy is undertaken. The natural history of herniations of the nucleus pulposus is complex and the relationship between the appearances on imaging and low back and radicular pain still has to be completely resolved. Considerable experimental work has been undertaken on the relationship between nerve compression, inflammation, and pain and recent studies on cytokines may lead to more precise pharmacologic therapies. The prime value of MR imaging may be in monitoring disk and nerve root changes in longitudinal studies of patients randomized to different therapeutic programs.

Neuron loss in cerebellar cortex of rats exposed to mercury vapor: a stereological study.

Mercury vapor produces tremor in humans and experimental animals. We have previously reported that mercury vapor intoxication over an 8-week period induces only subtle changes in dorsal root ganglia and nerve roots in rats. In the present study we have carried out stereological analyses of the cerebellum of the same rats, and demonstrated significant losses of Purkinje cells (12.7%, 2P = 0.005) and granule cells (15.6%, 2P = 0.016). All sizes of Purkinje cells were lost with an equal probability, i.e. there were no indication of any preferential loss of any subpopulation of the neurons. The volume of the granular cell layer was significantly reduced (18.9%, 2P = 0.0 15), whereas the volumes of the molecular layer and the white matter were unchanged. Previous stereological studies have demonstrated that methyl mercury intoxication primarily induces degeneration in the peripheral nervous system, while sparing the cerebellum. We therefore suggest that metallic mercury vapor and methyl mercury have different toxicological profiles in rats, where metallic mercury vapor mainly affects the central nervous system and methyl mercury mainly affects the peripheral nervous system.