The role of bone SPECT/CT in patients with persistent or recurrent lumbar pain following lumbar spine stabilization surgery.

PURPOSE: Despite recent advances in lumbar spine stabilization surgery (LSSS), a high number of patients continue to complain of persistent/recurrent lumbar pain after LSSS. Conventional imaging (plain radiography, CT and MRI) is commonly performed to assess potential lumbar pain generators, but findings are equivocal in approximately 20% of patients. The purpose of this study was to assess the diagnostic performance of 99mTc-HDP bone SPECT/CT in identifying potential pain generators in patients with persistent/recurrent lumbar pain after LSSS but in whom conventional diagnostic imaging is inconclusive. METHODS: A total of 187 patients (median age 56 years, 70 men) with persistent/recurrent lumbar pain following LSSS with inconclusive conventional imaging (plain radiography, CT and/or MRI) underwent 99mTc-HDP bone SPECT/CT and were included in the study. Tracer uptake on SPECT/CT, as an indicator of ongoing or altered osteoblastic activity, was assessed in the lumbar spine stabilization segment(s) and in adjacent segments. Uptake intensity was graded as (1) high (the same as or more than iliac crest uptake), (2) mild (the same as or more than nondiseased vertebral uptake but less than iliac crest uptake), or (3) negative (normal scan). Mild and high uptake were regarded as positive. RESULTS: In 160 of the 187 patients (85.6%), SPECT/CT showed positive mild or high tracer uptake in the LSSS region. More than half of the patients had abnormal tracer uptake in the stabilized segments (56.7%) and/or in the adjacent segments (55.6%). Although positive stabilized segment findings were commonly seen at <2 years (70.3%) and the rate decreased with time after LSSS, they were seen at >6 years after surgery in 38.2% of patients. In 51.4% of patients, abnormal activity was seen in the adjacent segments <2 years after LSSS, suggesting early/accelerated degeneration after surgery. The proportion of patients with abnormal activity in the adjacent segments increased to 67.3% at >6 years after LSSS (p < 0.05). Positive SPECT/CT findings in the stabilized segments were more frequent in patients with three or more stabilized segments (p < 0.05), but were not more frequent in the adjacent segments. Overall, positive SPECT/CT guided therapy in 64% of patients, which included facet joint/nerve root injections or re-do surgery at active sites and/or adjacent sites. CONCLUSION: Bone SPECT/CT is a sensitive diagnostic tool for identifying altered osteoblastic activity, which might be a pain generator in patients with persistent/recurrent pain after lumbar surgery especially when conventional imaging is inconclusive.

Atlantoaxial TB with paralysis: posterior-only cervical approach with good results.

Early posterior cervical approach is an effective strategy for patients with cervical tuberculosis in the appropriate circumstances.

Successful outcomes following transforaminal epidural steroid injections for C4/5 cervical disc prolapse associated with profound neurological deficit.

PURPOSE: To show that with C5 radiculopathy and profound neurological deficit, good outcomes can be obtained with injection therapy. METHOD: We present two cases of cervical radiculopathy secondary to disc prolapse associated with profound neurological deficit. In both cases, cervical injection therapy was used as the primary management. RESULTS: The two cases presented were both male, 59 and 36 years, and were diagnosed on MRI imaging with C4/5 disc prolapses. They presented with severe motor deficit and were both treated with foraminal epidural steroid injections, one of the patients also had two previous injections elsewhere prior to the first review. In both patients, pain and neurological deficit improved in a timely manner resulting in full recovery. MRI taken after recovery showed complete resorption of the disc prolapse in both cases. CONCLUSION: In C5 radiculopathy, even with severe neurological deficit, cervical injection therapy should be considered. These cases illustrate that excellent results can be obtained without the need for open surgery with its inherent risks.

Circulatory dynamics of the cauda equina in lumbar canal stenosis using dynamic contrast-enhanced magnetic resonance imaging.

BACKGROUND CONTEXT: There has been no study regarding the cauda equina circulation of patients with neurogenic intermittent claudication (NIC) in lumbar spinal canal stenosis (LSCS) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). PURPOSE: The mechanism responsible for the onset of NIC was investigated using DCE-MRI to examine changes in cauda equina blood flow in patients with LSCS. STUDY DESIGN: This was a retrospective longitudinal registry and magnetic resonance imaging study. PATIENT SAMPLE: The subjects consisted of 23 patients who had LSCS associated with NIC (stenosis group). Ten asymptomatic volunteers who did not have NIC served as controls (control group). In the LSCS group, the cross-sectional area of the dural sac was <75 mm2 at the site of most severe stenosis. These patients were further divided into single and double stenosis subgroups. OUTCOME MEASURES: The main measures we used were the signal intensity (S-I) ratio and the shape and size of the time intensity (T-I) curves. We compared these between the stenosis and control groups. METHODS: At first, plain T1-weighted MR images were obtained and the lumbar dural sac cross-sectional area was measured using a digitizer. For DCE-MRI, sagittal T1-weighted images of the same slice were acquired continuously for 10 minutes after administration of gadolinium as an intravenous bolus to observe the distribution of contrast medium (gadolinium) in the cauda equina. To objectively evaluate changes in contrast enhancement of the cauda equina at the site of canal stenosis, regions of interest were established. The signal intensity (SI) ratio was calculated to compare the signal intensities before and after contrast enhancement, and time-intensity curves were prepared to investigate changes over time. RESULTS: The static imaging findings and the changes of gadolinium uptake showed striking differences between the study and control patients. In the stenosis group, abnormal intrathecal enhancement showed around the site of stenosis on enhanced MR imaging. The SI ratio at the site of canal stenosis had a slower increase in the arterial phase when compared with that in the control group and remained high in the venous phase for up to 10 minutes. Finally, abnormal intrathecal enhancement was visible around the site of stenosis on enhanced MR imaging in all patients. CONCLUSIONS: These clinical data indicate that cauda equina nerve roots in the LSCS patients are pathologic even when symptoms are not elicited in the supine position, suggesting that intraradicular venous congestion and edema themselves do not influence the existence of radicular symptoms.

Isolated tuberculosis of the posterior spinal elements: case report and discussion of management.

In neurologically intact patients with isolated tuberculosis of the posterior spinal elements, surgical intervention can be of benefit in select patients by reducing instability, deformity and late complications.

Cervical synovial cyst.

Synovial cysts of the cervical spine are extremely rare. They can therefore pose a diagnostic challenge. We present an unusual case of acute symptomatology secondary to spontaneous haemorrhage into a cervical facet joint cyst.

Ten-year survival and clinical outcome of the AcroFlex lumbar disc replacement for the treatment of symptomatic disc degeneration.

BACKGROUND CONTEXT: We have previously reported on the osseointegration, stability, and preserved motion of the AcroFlex lumbar disc replacement (LDR) in a nonhuman primate model. Detailed biomechanical testing of the device predicted implant survival for at least 10 years of in vivo use. Significant improvements in the clinical outcome were reported at 2 years. However, mechanical failure of the polyolefin rubber was detected by fine-cut computed tomography (CT) in a number of subjects within 2 years. As a result, no further devices were implanted. PURPOSE: To report on the 10-year survival and clinical outcome of the AcroFlex elastomeric LDR when used for the treatment of one- or two-level symptomatic disc degeneration between L4 and S1. STUDY DESIGN: Prospective nonrandomized clinical trial with a mean 10-year follow-up. PATIENT SAMPLE: Twenty-eight patients with symptomatic disc degeneration who underwent AcroFlex LDR at one or two levels. OUTCOME MEASURES: Clinical: Visual Analog Score for back pain, Oswestry Disability Index (ODI), Low Back Outcome Score (LBOS), and Short Form-36 (SF-36). Survival: Kaplan-Meier analysis over 10 years with first revision surgery as the end point. Radiographic: Dynamic flexion/extension radiographs at 2 years. Magnetic resonance imaging (MRI) and CT scans at 10 years. METHODS: Twenty-eight subjects (14 male, mean age 41 years) with symptomatic disc degeneration unresponsive to nonsurgical treatment were enrolled into a prospective nonrandomized trial of the AcroFlex LDR. Visual analog score for back pain, ODI, LBOS, and SF-36 questionnaires were administered preoperatively at 6 months, 1, 2, and 10 years after the index procedure. All subjects were invited to undergo an MRI and for those with the device remaining in situ, a lumbar CT scan. Kaplan-Meier survival analysis was performed with first revision surgery as the end point. RESULTS: At a mean of 9 years, 8 months (range, 8 years, 8 months-11 years, 3 months) after surgery, 17 of 28 patients did not require a revision surgery, representing a cumulative survival of 60.7%. In contrast, 11 of 28 patients (39.3%) underwent a total of 14 revision procedures; 9 of 11 patients underwent a conversion to anterior lumbar interbody fusion supplemented with pedicle screw fixation. Indications for a revision included device failure in seven and disabling pain in four patients. Mean time to revision was 3 years, 10 months (range, 23 months-8 years, 4 months). Mean ODI at 10 years for nonrevision cases was 27.5 (±17.6) compared with 41.8 (±26) for revision cases. Mean improvement over 10 years in the ODI for nonrevision cases was 17.9 (±16.9) compared with 12 (±16.1) for revision cases. Similar trends were observed in LBOS and SF-36 scores. Radiographic findings in the revision group included midsubstance tears in the rubber, osteolysis, and implant displacement. CT findings in 11 of 17 survivors included heterotopic bone formation (85%), osteolysis (50%), and subsidence (14%). Magnetic resonance imaging in 14 of 23 subjects at the final follow-up demonstrated an adjacent-level disc degeneration in 68% of those with the AcroFlex LDR in situ and in 40% of those who had been converted to fusion. Skip-level disc degeneration was present in 44% of those with AcroFlex device in situ and in 20% of those who had been converted to fusion. CONCLUSIONS: The cumulative survival was 60.7% at 10 years when the first revision surgery was taken as the end point. The etiology of the implant failure prompting the revision included failure of osseointegration, midsubstance elastomeric tears, and osteolysis. Further use of this implant is not justified. The incidence of adjacent-level disc degeneration for the AcroFlex was comparable with that observed adjacent to the spinal fusion. Salvage procedures involving conversion to spinal fusion are technically demanding, but appear to improve outcomes modestly.

Lidocaine cytotoxicity to the bovine articular chondrocytes in vitro: changes in cell viability and proteoglycan metabolism.

PURPOSE: A lot of studies on the effect of intra-articular injections are clinical, but many questions on the effect of lidocaine to articular chondrocytes remain unanswered. This study was performed to determine the effects of varying concentrations and exposure times of lidocaine on the viability and proteoglycan metabolism of chondrocytes in vitro. METHOD: Cartilage was obtained from metatarsal joints of adult bovines. Chondrocytes in alginate beads were cultured in medium containing 6% fetal calf serum at 370 mOsmol at cell densities of 4 million cells/ml. They were then cultured for 24 h under 21% oxygen with 0.125, 0.25, 0.5, and 1% lidocaine and without lidocaine as control. The cell viability profile across intact beads was determined by manual counting using fluorescent probes and transmission electron microscopy. RESULT: Lactate production was measured enzymatically as a marker of energy metabolism. Glycosaminoglycan (GAG) accumulation was measured using a modified dimethylmethylene blue assay. Cell viability decreased in a time- and dose-dependent manner in the concentration range of 0.125-1.0% lidocaine under the confocal microscope. Under the electron microscope, apoptosis increased as the concentration of lidocaine increased. GAG accumulation/tissue volume decreases as the concentration of lidocaine increased. However, GAG produced per million cells and the rate of lactate production per live cell were significantly higher for cells cultured at 0.5 and 1% lidocaine than the control group. Bovine chondrocytes cultured in alginate beads under high oxygen pressure are negatively influenced by increasing concentrations of lidocaine. CONCLUSION: Cell viability and proteoglycan production (GAG accumulation/tissue volume) decreased as the concentration of lidocaine increased. These data suggest caution in prolonged exposure of cartilage to high concentration lidocaine. Repeated joint injection of lidocaine potentially worsens osteoarthrosis by accelerating cartilage degradation.

Microvascular system of the lumbar dorsal root ganglia in rats. Part I: a 3D analysis with scanning electron microscopy of vascular corrosion casts.

OBJECT: So far, the morphological features of the vascular system supplying the dorsal root ganglion (DRG) have been inferred only from microangiograms. However, in the past most of these studies lacked 3D observations. This study presents the details of the microvasculature of the lumbar DRG visualized by scanning electron microscopy of vascular corrosion casts. METHODS: Wistar rats were anesthetized with intraperitoneal sodium pentobarbital. After thoracotomy, the vascular system was perfused with heparinized saline, and Mercox resin was injected into the thoracic aorta. After polymerization of the resin, the vascular casts were macerated with potassium hydroxide, washed with water, and dried. The casts were examined with a scanning electron microscope. RESULTS: The vascular cast of the DRG was observed to have a higher density of vessels than the nerve root. Bifurcation or anastomoses of capillaries took place at approximately right angles, in a T-shaped pattern. Within the DRG, both the arterial supply and the capillary network contained blood flow control structures (ring-shaped constrictions in the cast probably representing a vascular sphincter in the microvessel). Three types of vessels could be distinguished: tortuous, straight, and bead-like capillaries. The dilations, bulges, and tortuousness of capillaries could serve the function of locally increasing the capillary surface area in a sensory neuron. CONCLUSIONS: The results of this study suggest a causal relationship between the metabolic demands of local neuronal activity and both the density of the capillary network and the placement of the blood flow control structures.

Microvascular system of the lumbar dorsal root ganglia in rats. Part II: neurogenic control of intraganglionic blood flow.

OBJECT: The dorsal root ganglion (DRG) should not be overlooked when considering the mechanism of low-back pain and sciatica, so it is important to understand the morphological features of the vascular system supplying the DRG. However, the neurogenic control of intraganglionic blood flow has received little attention in the past. The authors used an immunohistochemical technique to investigate the presence and distribution of autonomic and sensory nerves in blood vessels of the DRG. METHODS: Ten Wistar rats were used. To investigate the mechanism of vasomotion on the lumbar DRG, the authors used immunohistochemical methods. Sections were incubated overnight with antisera to tyrosine hydroxylase (TH), aromatic L-amino-acid decarboxylase (AADC), 5-hydroxytryptamine, substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP), somatostatin (SOM), neuropeptide Y (NPY), leucine-enkephalin, and cholineacetyl transferase (Ch-E). The avidin-biotin complex method was used as the immunohistochemical procedure, and the sections were observed under a light microscope. RESULTS: In the immunohistochemical study, TH-, AADC-, SP-, CGRP-, VIP-, SOM-, NPY-, and Ch-E-positive fibers were seen within the walls of blood vessels in the DRG. This study revealed the existence of a comprehensive perivascular adrenergic, cholinergic, and peptidergic innervation of intraganglionic blood vessels, with a possible role in neurogenic regulation (autoregulation) of intraganglionic circulation. CONCLUSIONS: The presence of perivascular nerve plexuses around intraganglionic microvessels suggests that autonomic nerves play an important role in intraganglionic circulation.

Vertebral hemangioma: an important differential in the evaluation of locally aggressive spinal lesions.

STUDY DESIGN: A case report and a discussion of recent published data. OBJECTIVE: To highlight the importance of vertebral hemangioma (VH) as a differential diagnosis in the evaluation of locally aggressive spinal lesions. SUMMARY OF BACKGROUND DATA: VH commonly occur as incidental findings, however, locally aggressive VH have been described. Difficulties in diagnosing these lesions are well reported and relate to changes in fat content causing uncharacteristic appearances on imaging. The management options for these lesions include a combination of observation, embolization, sclerotherapy, surgical decompression, or stabilization and radiotherapy. METHODS: A 45-year-old patient who was previously well presented with back pain and rapidly progressive paraparesis. Imaging confirmed the presence of an extensive lesion centered within the right T3 vertebral pedicle with intrusion into the spinal canal. Urgent surgical decompression was undertaken and was complicated by extensive intraoperative hemorrhage requiring massive transfusion. RESULTS: Histologically, the lesion was shown to be a cavernous VH with no evidence of malignancy. Following radiation oncology review, he was offered adjuvant radiotherapy to minimize the risks of recurrence. He achieved a near full neurologic recovery within 2 weeks and had a full recovery by 12 months. CONCLUSION: VH should be considered in the evaluation of locally aggressive spinal lesions. Angiography is a useful adjunct in the evaluation of these lesions, both as a diagnostic and therapeutic tool. After diagnosed correctly a wide range of treatment options exist that may prevent the patient from undergoing major surgical resection and reconstruction procedures, which may be associated with high rates of morbidity.

Lidocaine cytotoxicity to the zygapophysial joints in rabbits: changes in cell viability and proteoglycan metabolism in vitro.

STUDY DESIGN.: To examine whether lidocaine cytotoxicity to chondrocytes has been implicated in the development of osteoarthritis of the zygapophysial joints. OBJECTIVE.: This study was performed to determine the effects of varying concentrations and exposure times of lidocaine on the viability and proteoglycan metabolism of rabbit zygapophysial chondrocytes in vitro. SUMMARY OF BACKGROUND DATA.: Zygapophysial joint injections are commonly administered with lidocaine for chronic spinal pain in orthopedic treatment. A lot of studies on the effect of zygapophysial joint injections are clinical, but many questions on the effect of lidocaine to zygapophysial chondrocytes remain unanswered. METHODS.: Cartilage was obtained from zygapophysial joints of adult rabbits. Chondrocytes in alginate beads were cultured in medium containing 6% fetal calf serum at 370 mOsmol at cell densities of 4 million cells/mL. They were then cultured for 24 hours under 21% oxygen with 0.125%, 0.25%, 0.5%, and 1% lidocaine, and without lidocaine as control. The cell viability profile across intact beads was determined by manual counting using fluorescent probes (LIVE/DEAD assay) and transmission electron microscopy. Lactate production was measured enzymatically as a marker of energy metabolism. Glycosaminoglycan (GAG) accumulation was measured using a modified dimethylmethylene blue assay. RESULTS.: Cell viability decreased in a time- and dose-dependent manner in the concentration range of 0.125% to 1.0% lidocaine under the confocal microscope. Under the electron microscope, apoptosis increased as the concentration of lidocaine increased. GAG accumulation/tissue volume decreases as the concentration of lidocaine increased. However, GAG produced per million cells and the rate of lactate production per live cell was significantly higher for cells cultured at 0.5% and 1% lidocaine than the control group. CONCLUSION.: While these in vitro results cannot be directly extrapolated to the clinical setting, this data suggestcaution in prolonged exposure of zygapophysial cartilage to high concentration lidocaine.

Parosteal aneurysmal bone cyst of the humerus with birdcage-like ossification on three-dimensional CT scanning: a case report.

A rare case of parosteal aneurysmal bone cyst arising from the humerus in a 7-year-old boy is reported. Plain radiography and CT scanning revealed a marked periosteal reaction and a soft tissue mass surrounded by bone. Erosion of the cortex did not extend to involve the medulla. Three-dimensional CT scanning (3-DCT) revealed a birdcage-like ossified structure that was attached to the cortex of the humerus. 3-DCT was also used to visualize the extent of the tumor and the architecture of the bone, providing important information for planning of surgery. Inside the tumor, there were a number of fluid-fluid levels on T1-weighted MRI and high intensity areas on T2-weighted images. Pathologic examination revealed a central cavity containing a large volume of blood in the tumor and reactive osteogenesis mainly at the marginal regions, and these findings reflected the birdcage-like ossified structure observed by 3-DCT. Pathological examination was required to rule out osteosarcoma in particular, but a diagnosis of parosteal aneurysmal bone cyst was made because of the absence of findings suggestive of malignancy. The tumor was excised en bloc with a clear margin. At 3 years after surgery, there is no evidence of recurrent tumor.

A phenotypic comparison of proteoglycan production of intervertebral disc cells isolated from rats, rabbits, and bovine tails; which animal model is most suitable to study tissue engineering and biological repair of human disc disorders?

The nucleus pulposus (NP) of the intervertebral disc in cattle and humans shows the most dramatic changes with aging of any cartilaginous tissue. In humans, notochordal cells disappear from the NP and are replaced with chondrocytic cells by adolescence. However, notochordal cells of the NP persist into adult life in some species, such as rats and rabbits. Therefore, comparison of the metabolic activity of notochordal and nonnotochordal cells is considered to be important for determining the type of cell to use for transplantation to regenerate intervertebral discs. In this study, we investigated the notochordal NP cells of rats and rabbits, as well as nonnotochordal (chondrocyte-like) bovine NP cells, in a three-dimensional culture system to examine whether proteoglycan metabolism varied among these three cell types. As a result, bovine NP cells produced around 0.18 mg/mL of glycosaminoglycan after culture for 5 days, while rat and rabbit NP cells produced about four and two times more glycosaminoglycan than bovine cells, respectively. In conclusion, this study demonstrated marked differences of energy metabolism and production of matrix components between notochordal and nonnotochordal NP cells. Animals with notochordal cells in the NP, such as rats and rabbits, may not provide good models for investigation of biological repair and tissue engineering for human disc disorders.

Vasomotion of intraradicular microvessels in rat.

STUDY DESIGN: This study is to investigate the changes of vasomotion of intraradicular microvessels in vivo. OBJECTIVE: We have observed microvascular corrosion casts of the lumbar nerve root by scanning electron microscopy and used an immunohistochemical technique to investigate the presence and distribution of autonomic and sensory nerve in blood vessels of the nerve root. SUMMARY OF BACKGROUND DATA: It is generally considered that the genesis of radiculopathy associated with the degenerative conditions of the spine may result from both mechanical compression and circulatory disturbance. However, the neurogenic control of intraradicular blood flow has received little attention in the past. METHODS: For three-dimensional observation of intraradicular vessels, we used scanning electron microscopic examination of microvascular corrosion casts in ten Wister rats. To investigate the mechanism of vasomotion of the nerve root, we used immunohistochemical methods. The sections were incubated overnight with antisera to tyrosine hydroxylase, choline acetyl transferase, substance P, calcitonin-gene-related peptide, vasoactive intestinal peptide, somatostatin, neuropeptide Y, leucine-enkephalin, cholecystokinin octapeptide, brain-nitric oxide synthase, and endothelium-nitric oxide synthase. Abidin-biotin complex method was used as the immunohistochemical procedure and the sections were observed under the light microscope. RESULTS: The general view of whole vascular casts of the lumbar spinal cord and nerve roots showed a high density of vessels. Bifurcation or anastomoses of capillaries approximately took place at right angles in a T-shaped pattern and capillaries showed a lot of ring-like compressions. This ring-like compression on the cast may represent a vascular sphincter in the microvessels. This study also reveals the existence of perivascular adrenergic, cholinergic, peptidergic, and nitroxydergic innervation with a possible role in neurogenic regulation of nerve root circulation. CONCLUSION: Perivascular nerve plexuses around intraradicular microvessels suggest that the autonomic nerves play an important role in intraradicular circulation.

Ultrastructural analysis on lumbar disc herniation using surgical specimens: role of neovascularization and macrophages in hernias.

STUDY DESIGN: The mechanisms responsible for the spontaneous regression of lumbar disc herniation (LDH) were studied by examining herniated tissue collected at operation from patients with LDH. OBJECTIVE: The aim of the present study was to investigate the role of neovascularization and macrophages in hernias when spontaneous regression of LDH occurred. SUMMARY OF BACKGROUND DATA: Spontaneous regression of LDHs has already been demonstrated by diagnostic imaging with tools such as magnetic resonance imaging. However, there have been few studies on the mechanisms of spontaneous regression based on pathologic examination of herniated tissue. In particular, there has been no detailed work on the role of macrophages, which are thought to be closely associated with spontaneous regression. METHODS: The magnetic resonance imaging and operative findings of 73 patients who underwent surgery were investigated, and specimens collected during surgery were examined by light and transmission electron microscopy. RESULTS: Capillaries that invade the hernia and macrophages derived from monocytes migrating out of these capillaries are considered to be important factors in the regression of the herniated disc. Macrophages contain lysosomes filled with collagen-degrading enzymes that break down substances after phagocytosis, whereas primary lysosomes are secreted by these cells and break down intercellular substances such as collagen. Both of these mechanisms are closely involved in the regression of herniation. CONCLUSION: The inflammatory response that occurs around hernia tissue in the epidural space is believed to play an important role in herniated disc resorption, although it may also have a harmful effect on the adjacent nerve root. Therefore, control of the inflammatory reaction is an important challenge when treating patients with disc herniation.

Changes in blood flow, oxygen tension, action potentials, and vascular permeability induced by arterial ischemia or venous congestion on the lumbar dorsal root ganglia in dogs.

It is generally believed that radiculopathy associated with the degenerative conditions of the spine may result from both mechanical compression and circulatory disturbance. However, the basic pathophysiology of circulatory disturbance induced by ischemia and congestion is not fully understood. This study investigated the effect of ischemia and congestion on the dorsal root ganglion (DRG) using an in vivo model. The sixth and seventh lumbar laminae were removed and the seventh lumbar DRG was exposed using adult dogs. The aorta was clamped as an ischemic model in the DRG, and the inferior vena cava was clamped as a congestion model at the sixth costal level for 30 min using forceps transpleurally. Measurements of blood flow, partial oxygen pressure, and action potentials in the DRG were recorded over a period of 1 h after clamp release. Finally, we examined the status of intraganglionic blood permeability under a fluorescence microscope following injection of Evans blue albumin into the cephalic vein to determine the type of circulatory disturbance occurring in the DRG. Immediately after inferior vena cava clamping, the central venous pressure increased approximately four times and marked extravasation of protein tracers was induced in the lumbar DRG. Blood flow, partial oxygen pressures, and action potentials within the DRG were more severely affected by the aorta clamping; however, this ischemic model did not reveal any permeability changes in the DRG. The permeability change in the DRG was more easily increased via venous congestion than by arterial ischemia. The intraganglionic venous flow was stopped with compression at much lower pressures than that needed to impact arterial flow. From a clinical perspective, intraganglionic edema formation, rather than arterial ischemia, may be an earlier phenomenon inducing DRG dysfunction.

Visualization of intraneural edema using gadolinium-enhanced magnetic resonance imaging of carpal tunnel syndrome.

BACKGROUND: In general, carpal tunnel syndrome (CTS) is diagnosed based mainly on clinical findings and electrophysiology. However, the pathological state of the compressed median nerve could not be shown on imaging. Gadolinium-enhanced magnetic resonance (MR) imaging may give us an idea about the status of the blood-nerve barrier of peripheral nerves. Therefore, detecting intraneural edema may be a way of diagnosing entrapment neuropathy. The present study investigated the diagnostic role of gadolinium-enhanced MR imaging of CTS. METHODS: The subjects were 23 patients (34 hands) with idiopathic CTS. To serve as control subjects, 12 wrists of asymptomatic volunteers were studied. Using the spin-echo method, T1- and T2-weighted axial MR images were obtained. Intravenously injected gadolinium was used to obtain enhanced images. We studied the relation between nerve enhancement and the symptomatology. RESULTS: After intravenous injection of gadolinium, there was no enhancement of the unaffected nerves in the carpal tunnels of the control group. Gadolinium enhancement was found in only 87% of patients with CTS who visited the hospital at an early stage and therefore had no nerve deficiency on electrophysiological studies (39%). Based on this finding, during the early stages when the nerve is in a state of neuropraxia, gadolinium-enhanced MR imaging of the median nerve might prove to be the most sensitive modality for detecting early nerve dysfunction. MR imaging also revealed a higher frequency of enhancement in the advanced stage of CTS with muscle atrophy. CONCLUSIONS: We conclude that gadolinium-enhanced MR imaging can detect not only morphological changes but also pathological changes of the median nerve in patients with CTS. Currently, gadolinium-enhanced-MR imaging is probably most commonly used to image patients who have ambiguous electrodiagnostic studies and clinical examination in an early stage of CTS.

Fine structure of cartilage canal and vascular buds in the rabbit vertebral endplate. Laboratory investigation.

OBJECT: The vascular terminations (vascular buds) in the bone-disc junction area are structurally very similar to cartilage. In all previous studies to date, however, the roles of cartilage canals and vascular buds were mainly discussed using histological and transparent sections but not electron microscopic sections. The purpose of this study was to clarify the ultrastructure of the vascular bud seen in the bone-disc junction in comparison to the cartilage canal. METHODS: Japanese white rabbits from 2 days to 6 months of age were used in this study. The bone-disc junctions were examined by microangiogram and light and electron microscopy, and morphological changes and their association with the age of the animals were noted. RESULTS: The fine structure of the vascular bud was similar to that of the cartilage canal that nourished the growing cartilage. They were composed of arteries, veins, capillaries, cells resembling fibroblasts, and macrophages. The capillaries in the cartilage canal were all the fenestrated type. Vascular buds were seen over the entire bone-cartilage interface, with maximum density in the area related to the nucleus pulposus. They projected into the bone-disc junction area from the vertebral body contacting the cartilaginous endplate directly. CONCLUSIONS: The results of this study clarify the formation process and ultrastructure of the vascular bud seen in the bone-disc junction. The authors found a strong structural resemblance between the vascular bud and the cartilage canal and hypothesize that the immature cells seen surrounding the cartilage canal and vascular bud represent a common precursor for the 3 main types of connective tissue cells seen during early vertebral development.