Distribution of morphine and meperidine after intrathecal administration in rat and mouse

Morphine and meperidine distribution in the neuroaxis were studied in rats after intrathecal injection through catheters ending at the lumbar level. 14C-Morphine and 3H-meperidine were injected with pharmacologic doses of each drug. Radioactivity was measured in spinal cord segments at different times. At 14 min the segment with maximum morphine concentration (T11-12) contained 8.6 +/- 2.4 (mean +/- SD) pmol/mg, a value 215 times higher than would be observed if distribution in the body were homogeneous. The ratio between concentration in the most rostral segment (C3-4) and in the segment with maximal concentration was 0.21 +/- 0.10. At 14 min the segment with maximum meperidine concentration (T9-10) contained 161.4 +/- 33.9 pmol/mg wet tissue, a value 75 times higher than would be seen with even distribution in the body. The ratio (C3-4 vs. T9-10) was 0.10 +/- 0.04 at this time. The distribution of 14C-morphine in the whole central nervous system (CNS) was studied in mice by whole body autoradiography after intrathecal injections of 5 microliters at the L5-6 level. High levels of radioactivity were detected in the whole spinal cord and in brain regions close to the basal cisterns until 2 h after injection. At 4 h only the caudal part of the spinal cord had detectable levels of radioactivity. The per cent of the injected dose of morphine that was recovered from the spinal cord was 26.5 +/- 4.5 at 14 min, 19.9 +/- 8.8 at 44 min, and 4.5 +/- 1.7 at 179 min after injection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Near-anatomical reduction and stabilization of burst fractures of the lower thoracic or lumbar spine

Summary Thirty-one consecutive symptomatic patients with burst fractures of the lower thoracic or lumbar spine (T11-L4) were treated by early surgery in a 36-month period, with near-anatomical reduction being achieved via the postero-lateral route. Fusion and reconstruction of the vertebral body was done by using autologous or processed bovine bone. Correction of the kyphotic deformity was obtained by using distraction rods or transpedicular devices. The post-operative mean degree of kyphosis, percent vertebral height, and percent canal stenosis showed statistically significant differences, compared with the corresponding pre-operative mean values. All but one of the 25 patiens with incomplete paraplegia exhibited neurological improvement, with complete recovery occurring in 20 cases (median followup: 16 months) irrespective of the location of the lesion at the thoraco-lumbar junction (T11-L1) or the lower lumbar segment (L2-L4). Out of the 6 patients with pre-operative complete paraplegia, useful motor power returned in one case with a lesion below L1.The results confirm the suitability of the postero-lateral route and are consistent with the assumption that early near-anatomical reduction and stabilization favours maximum neurological recovery in symptomatic patients.     

椎管内胸神经根移位至腰神经根的解剖学研究

目的 了解椎管内T9～12神经根移位修复L2～4神经根、恢复截瘫后股四头肌功能的解剖学基础.方法 5 具成人尸体标本,其中男性2具,女性3具.完全显露胸段及腰段椎管,观察T9～L4神经根在脊髓上发出的部位,T12及L1椎体水平与椎管内各神经根之间的关系;测量T9～L4神经根在椎管内的长度,T9～L4神经根的直径,T9～L4各神经根起始部之间的距离,T9～12神经根自硬脊膜穿出到L2椎体中部水平的距离.结果 T9神经根发自T9椎体中部,L4神经根发自L2椎体中部;T9～L4神经根在椎管内的长度均值分别为16.12、22.97、30.43、43.47、56.02、70.03、88.70和113.65mm.T9～L4神经根的直径均值分别为2.45、2.04、1.96、2.18、2.32、2.56、3.10和3.26 mm.各神经根起始部之间的距离均值分别为22.87、25.08、28.47、27.38、29.78、31.93和31.00 mm.T9～12神经根自硬脊膜穿出到L2椎体中部水平的距离均值分别为118.69、95.82、70.74和42.27 mm.结论 T9～12神经根均可以作为动力神经;可以将L2椎体的中部作为受体神经吻合平面修复L2～4神经根.     

Perspective graphics as a means of portraying the distribution of radiolabelled ligands in the spinal cord--a pilot study using intrathecally administered 3H morphine

Tritium-labelled morphine sulphate was injected into the lumbar (L4-5) subarachnoid space of an adult male baboon. Three hours after injection, the animal was sacrificed. Using quantitative light microscopic autoradiographic mapping techniques, contour and perspective diagrams were prepared that described the position of radiolabel and by inference the distribution of morphine binding sites within the spinal cord. High concentrations of 3H was found in the medial regions of laminae I, II (substantia gelatinosa) and III of the dorsal horns. Smaller, but significant levels were seen bilaterally in the spinal anterolateral quadrant. Minimal 3H activity was seen in the remainder of the spinal cord with the lowest level being recorded in the spinal canal. Perspective graphics proved a precise and attractive method for locating the position and quantifying the concentration of radiolabel in baboon spinal cord.     

An experimental study of sensory innervation of the ureter in the dog using wheat germ agglutinin-horseradish peroxidase conjugates]

The sensory innervations of the ureter in the dog were studied using the anterograde and retrograde axonal transport of wheat germ agglutinin-horseradish peroxidase conjugates (WGA-HRP). Following upper ureteral injections, labeled cells were observed in the ipsilateral T7-L3 spinal ganglia to the injection site, with the greatest concentration at the T12-L2 levels. And labeled cells were seen in the contralateral T7--L3 spinal ganglia to the injection site with the greatest concentration at the T10 and L3 ganglia. Lower ureter injections resulted in the labeling of ipsilateral T11-Co1 and contralateral T9-Co1 spinal ganglia, with highest concentration at the ipsilateral L3 and S2 levels. Following thoracic and lumbar spinal ganglia T12, L1-L3 injections labeled fibers bundles were observed in the adventitia of the upper and lower ureter. Some labeled fibers were bifurcated from these bundles and passed through the two layers of the smooth muscles. In tunica submucosa and tunica propria mucosae, many labeled fibers were observed. A few labeled fibers were seen in the epithelium. After injections into the sacral and coccygeal spinal ganglia S1-Co1, labeled fibers were not observed in the upper ureter. Course and distribution of labeled fibers in the lower ureter were similar to those of the case in which injection was done into the thoracic and lumbar spinal ganglia.     

Concomitant Administration of Morphine and an N-Methyl-D-Aspartate Receptor Antagonist Profoundly Reduces Inflammatory Evoked Spinal c-Fos Expression

Background: After intraplantar injection of carrageenin, peripheral inflammation and spinal c-Fos expression are extensive, with the latter being sensitive to both large doses of morphine or N-methyl-D-aspartate receptor antagonism. The authors investigated the effects of coadministered morphine and (+)-HA966, a functional antagonist at the glycine site of the N-methyl-D-aspartate receptor, on the two parameters.

Methods: The effects of morphine, (+)-HA966 and coadministration of morphine and (+)-HA966 on spinal c-Fos expression in segments L4-L5 of the spinal cord and peripheral edema, induced at 1.5 h and 3 h after intraplantar carrageenin (6 mg/150 micro liter) were studied.

Results: Previous coadministration of 0.3 mg/kg systemic morphine and 2.5 mg/kg subcutaneous (+)-HA966 significantly reduced c-Fos expression induced 1.5 h, but not 3 h, after carrageenin administration. However, coadministration of a larger dose of morphine (3 mg/kg) with (+)-HA966 (2.5 mg/kg) reduced c-Fos expression at 3 h after carrageenin administration, in a partially naloxone-reversible manner.     

Anatomic considerations for anterior instrumentation of the lumbar spine.

One hundred seventy lumbar vertebrae from L1-L4 were used to quantitatively evaluate the lumbar vertebral body and examine the relationship of the maximum posterior angles of screw placement to the spinal canal. Anatomic evaluation included dimensions of the vertebral body. Three entrance points on the lateral aspect of the vertebral body for screw insertion and an additional point 3 mm from the posterolateral corner of the spinal canal were defined and marked. The maximum posterior screw angles were determined as the angles between the line connecting the entrance point with the additional point and the coronal plane. Results showed that vertebral body dimensions increased from L1-L4. The average vertebral body depth, width, and height were approximately 26 mm, 36 mm, and 22 mm at L1, and 30 mm, 44 mm, and 23 mm at L4, respectively. The spinal canal may be penetrated if the screws are directed posteriorly 2 degrees-5 degrees at L1 - L2 and 9 degrees - 14 degrees at L3-L4 starting at the junction between the pedicle and vertebral body, 22 degrees - 32 degrees at L1-L4 from the level of 10 mm anterior to the junction, and 43 degrees -50 degrees from the level of 20 mm anterior to the junction. Therefore, mid-body screws should be directed perpendicular to the lateral plane of the vertebral body. For a more anteriorly placed screw, slightly posterior angulation is recommended.     

Lumbar epidural morphine in humans and supraspinal analgesia to experimental heat pain

BACKGROUND: Epidural administration of morphine is a common analgesic technique to manage pain. Morphine spreads from the epidural space to the cerebrospinal fluid and then rostrally, causing side effects mediated by the brain stem. However, data on the rostral spread of morphine-mediated analgesia are sparse. This study examined the rostral spread of analgesic effects on heat and electrical pain after epidural administration of morphine. METHODS: In a randomized, double-blinded, placebo-controlled, crossover study, 5 mg morphine or saline placebo were injected into the lumbar epidural space in nine healthy volunteers. Correct needle placement was confirmed with fluoroscopy. Analgesia to experimental nociceptive heat and electrical stimuli was measured at lumbar (L4), thoracic (T10), cervical (C2), and trigeminal (V2) levels before and 2, 5, 10, and 24 h after epidural injection. Plasma samples for assaying morphine concentrations were drawn before and after each analgesic evaluation. RESULTS: Epidural morphine significantly attenuated experimental heat pain at all dermatomes tested compared with saline placebo. Analgesic effects were significant at L4 after 2, 5, and 10 h, at T10 after 5, 10, and 24 h, and at V2 after 10 h. Electrical pain was attenuated at the lumbar and thoracic but not at the cervical dermatome. Analgesic effects were significant at L4 after 2, 5, and 10 h and at T10 after 5 and 10 h. Morphine plasma concentrations were below the detection limit (1 ng/ml) in eight of the nine subjects 10 h after epidural injection. CONCLUSIONS: Lumbar epidural injection of morphine attenuated cutaneous heat pain up to the trigeminal dermatome during a 24-h observation period. In a clinical context, this implies that some types of pain may be attenuated up to the supraspinal level after lumbar epidural administration of morphine.     

Anatomical configuration of the spinal column in the supine position. II. Comparison of pregnant and non-pregnant women

To assess the changes in the curvature of the spinal column in the supine position during pregnancy, we studied seven pregnant (32-37 weeks of pregnancy) and seven non-pregnant women using magnetic resonance imaging. T1-weighted sagittal midline magnetic resonance images of the spinal column were obtained with subjects in the supine position with left tilt. There was no significant difference in the maximum angle of decline of the lumbar spinal canal between the pregnant (mean 12.4 (SD 3.3) degrees) and non-pregnant (13.4 (3.9) degrees) groups. The maximum angle of incline of the upper thoracic spinal canal was smaller in the pregnant (15.8 (2.9) degrees) than in the non-pregnant (22.7 (6.0) degrees) group. The highest point of the lumbar spinal canal was located at a lower lumbar region in the pregnant (median L4-5 (range L4 to L4-5)) than in the non-pregnant (L4 (L3-4 to L4)) group. The lowest point of the thoracic spinal canal was located at a higher thoracic region in the pregnant (T6-7 (T6 to T7-8)) than in the non-pregnant (T8 (T6-7 to T9)) group. This study revealed that the apex of lumbar lordosis was caudad and thoracic kyphosis was reduced in the supine position in the later stages of pregnancy. These changes in the curvature of the spinal column may explain, in part, the enhanced cephalad spread of subarachnoid hyperbaric anaesthetic solutions in the later stages of pregnancy.      

A Comparison of Epidural Morphine and Epidural Bupivacaine for Postoperative Pain Relief

In 32 patients subjected to total hip replacement, postoperative pain relief was achieved by random treatment with either 5 mg of morphine in 10 ml of saline (n = 15) or 6–8 ml of 0.5% bupivacaine with epinephrine (n = 17), both drugs administered by the lumbar epidural route. In an additional group of 10 patients, post-traumatic thoracic or post-operative abdominal pain was relieved first by 4–6 ml of 0.5% bupivacaine with epinephrine and subsequently by 5 mg of morphine in 10 ml of saline, both drugs being administered by the thoracic epidural route. The duration of analgesia was significantly longer, on average, with morphine (28 h) than with bupivacaine (4.3 h) when the drugs were given by the lumbar route. Thoracic administration of morphine also resulted in a significantly longer duration of pain relief (on average 9.8 h) than that of bupivacaine (3.8 h). Morphine gave satisfactory pain relief in all cases. It was not associated with motor block, loss of sensitivity to temperature, touch, or pin-prick, or any signs of sympathetic block, as was the case with epidural bupivacaine. Plasma concentrations of morphine were not detectable 8 h after injection, though the patients still had pain relief. One case of delayed severe respiratory depression occurred 6 h after morphine injection via the thoracic route. Epidural morphine analgesia should therefore be reserved for patients in whom continual surveillance is possible, at least until more is known about the pharmacokinetics of narcotics in the epidural and subarachnoid space.     

Sensory innervation of the dorsal portion of the lumbar intervertebral discs in rats

STUDY DESIGN: The levels of dorsal root ganglions (DRGs) innervating the dorsal portion of the lumbar intervertebral discs from L1-L2 to L4-L5 were investigated in rats by the retrograde transport method. The pathways and functions of nerve fibers supplying the dorsal portion of the discs were investigated by denervation and immuno-histochemistry. OBJECTIVES: To investigate the sensory innervation of the dorsal portion of the lumbar intervertebral discs in rats. SUMMARY OF BACKGROUND DATA: The dorsal portion of the L5-L6 disc has been reported to be innervated multisegmentally, and anesthetic blockade of the paravertebral sympathetic trunks and the L2 spinal nerve can relieve discogenic low back pain. However, sensory innervation of the dorsal portion of the lumbar discs at other levels has not been clarified. METHODS: A retrograde transport of Fluoro-Gold was used. We studied a nonsympathectomy group (n = 44) and a sympathectomy group (n = 50) in which paravertebral sympathetic trunks were resected from L1 to L5 levels. Using a ventral approach, Fluoro-Gold crystals were inserted into the dorsal portion of the L1-L2, L2-L3, L3-L4, and L4-L5 discs. Seven days after surgery, Fluoro-Gold-labeled neurons were counted in the bilateral dorsal root ganglions from T10 to L6. RESULTS: Fluoro-Gold-labeled neurons were distributed in dorsal root ganglions from T11 to L5 levels in the nonsympathectomy group. However, in the sympathectomy group the number of labeled neurons was less than that of the nonsympathectomy group in T11, T12, and T13 dorsal root ganglions of the L1-L2 disc group, in T12, T13, and L1 dorsal root ganglions of the L2-L3 disc group, in T12, T13, L1, and L2 dorsal root ganglions of the L3-L4 disc group, and in T12, T13, L1, and L2 dorsal root ganglions of the L4-L5 disc group. CONCLUSION: The dorsal portion of the lumbar discs from L1-L2 to L4-L5 is multisegmentally innervated by the T11 through L5 dorsal root ganglions. Sensory fibers from the upper dorsal root ganglions innervate the dorsal portion of the discs via the paravertebral sympathetic trunks, although those from the lower dorsal root ganglions innervate via the sinuvertebral nerves. Furthermore, sensory nerve fibers enter the paravertebral sympathetic trunks through the corresponding ramus communicans and reach the dorsal root ganglions via each ramus communicans at the L2 and/or more cranial levels.     

The anatomy of the thoracic spinal canal investigated with magnetic resonance imaging (MRI)

BACKGROUND AND OBJECTIVES: Anesthesiologists are reluctant to consider higher levels for spinal anesthesia, largely due to direct threats to the spinal cord. The goal of this study is to investigate, with magnetic resonance imaging (MRI), the distances between the relevant structures of the spinal canal (spinal cord, thecal tissue, etc.) to determine modal anatomical positions for neuraxial anesthesia. METHOD: A group of 19 patients were imaged with an MRI scanner in supine position. Medial sagittal slices of the thoracic and lumbar spine were measured for the relative distances between anatomical structures, including epidural space, dura, and spinal cord. RESULTS: The posterior dura - spinal cord distance is significantly greater in the middle thoracic region than at upper and lower thoracic levels (e.g. T6 9.5 +/- 1.8 mm, T12 3.7 +/- 1.2 mm, p < 0.001, T1 4.7 +/- 1.7 mm, p < 0.001). There is variation in modal distances between the structures important for neuraxial anesthesia, at different levels of the spinal canal. CONCLUSIONS: The spinal cord tends to follow the straightest line through the imposed geometry of the spine. Considering the necessary angle of entry of the needle at mid-thoracic levels, there is relatively (more than at upper thoracic and lumbar levels) substantial separation of cord and surrounding thecal tissue. Anesthesiologists perform spinal blockades up to the L2-L3 interspace, but avoid higher levels for fear of neurological damage. The information that there is substantially more space in the dorsal subarachnoid space at thoracic level, might lead to potential applications in regional anesthesia. In contrast, the cauda equina sits more dorsally in the lumbar region.     

Degenerative lumbar listhesis and bone mineral density in elderly women. The study of osteoporotic fractures

STUDY DESIGN: A cross-sectional and prospective study. OBJECTIVES: To investigate the association between lumbar listhesis in elderly white women and bone mineral density at the spine, hip, radius, and calcaneus. SUMMARY OF BACKGROUND DATA: Several types of degenerative spinal changes have been found to be associated with high bone mineral density at the spine and other body sites. METHODS: Lateral radiographs of the lumbar spine for 1400 elderly women enrolled in the Study of Osteoporotic Fractures were digitized. Listhesis (antero and retro) was assessed at L3-L4, L4-L5, and L5-S1. Bone mineral density was measured at the spine, hip, calcaneus, and the distal and proximal radius. RESULTS: After adjusting the data for age and body mass index, retrolisthesis at L3-L4, L4-L5, and L5-S1 was associated with mean spinal bone mineral density levels that were 9% to 13% higher compared with those levels in women with no listhesis (P < 0.0001). In addition, bone mineral density at the hip and appendicular sites increased from 4% to 9%. The mean lumbar spinal bone mineral density of women with anterolisthesis at L3-L4 was 12% higher (P < 0.05) than that of women with no listhesis; it was the same for both groups at L4-L5 and was 7% lower (P < 0.005) at L5-S1. At L5-S1 the bone mineral density level at the hip and appendicular sites was also lower among the women with anterolisthesis at that level. CONCLUSIONS: This study suggests that retrolisthesis, like other spinal degenerative diseases, is associated with increased spinal bone mineral density. Anterolisthesis, however, may involve a different etiology, because its association with bone mineral density varies by spinal level.     

CSF and plasma pharmacokinetics of the NMDA receptor antagonist CPP after intrathecal, extradural and i.v. administration in anaesthetized pigs

The N-methyl-D-aspartate (NMDA) receptor complex plays a centraldegrees in the modulation of neuronal information in the centralnervous system. This study was designed to examine the pharmacokineticsof the NMDA antagonist 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonicacid (CPP) in plasma and cerebrospinal fluid (CSF) and rostralspread in the CSF after lumbar intrathecal, extradural and i.v.administration. Anaesthetized pigs were given a lumbar intrathecal,lumbar extradural or an i.v. injection of a mixture of [³H]labelledand unlabelled CPP. CSF was sampled over 10 h through intrathecalcatheters positioned at the L1, T5 and C1 vertebral levels.Blood samples were obtained over the same period. Haemodynamicand arterial blood-gas variables and acid-base balance weremonitored during the study. The area under the radioactivityconcentration-time curves showed a gradient between cervicaland lumbar CSF radioactivity of about 1:2500 after intrathecaladministration and about 1:140 after extradural administration,indicating that only small fractions of lumbar administeredCPP spread rostrally. About 2% of an extradurally administereddose was found in the CSF. After i.v. administration of [³H]CPP,clearance was mean 122 (SEM 16) ml min^–1 and the CSF:serumradioactivity gradient was approximately 1:4. The half-lifeof [³H]CPP varied little (mean range 94–191 min) irrespectiveof the route of administration or the level of sampling. Cervicalradioactivity after lumbar intrathecal administration probablyresulted from rostral transport via CSF bulk flow, whereas afterextradural administration, systemic absorption and redistributionvia the blood-brain barrier probably contributed. Renal excretionwas the main route of systemic elimination. No effects on haemodynamics,arterial blood-gas tensions or acid-base balance could be correlatedwith intrathecal or extradural administration of CPP. The steepgradient between cervical and lumbar concentrations of [³H]CPPsuggests that it may be possible to administer CPP spinallyat the lumbar level in pharmacologically active doses with littledistribution to the supraspinal level.     

Distribution of 3H-morphine following lumbar subarachnoid injection in unanesthetized rabbits

Morphine sulfate (40-100 micrograms) and 3H-morphine (125-200 pmol) were injected into the lumbar subarachnoid space of 18 unanesthetized rabbits through a surgically implanted catheter. Radioactivity remaining in the spinal cord 2, 4, 6, and 12 h later revealed recovery (mean +/- SEM) of 45 +/- 5.6% (n = 3), 30.5 +/- 14.1% (n = 4), 11.23 +/- 4.4% (n = 3), and 3.7 +/- 1.1% (n = 3), respectively, of the injected radioactivity. Tritiated morphine was found to be predominantly centered around the injection site, with limited rostral and caudal spread in the cord. No significant radioactivity was detected in plasma or cerebrospinal fluid (CSF) samples from the cisterna magna taken at 5, 15, 30, min and 1, 2, 4, 6, 12, and 24 h after receiving radioactive labeled drug (with the exception of that in one rabbit). Of the injected radioactivity, 75% was recovered in the urine in 12 h. These results suggest that the persistence of morphine in the spinal cord could account for its prolonged analgesic effect following intrathecal administration.     

Lumbar Epidural Morphine in Humans and Supraspinal Analgesia to Experimental Heat Pain

Background: Epidural administration of morphine is a common analgesic technique to manage pain. Morphine spreads from the epidural space to the cerebrospinal fluid and then rostrally, causing side effects mediated by the brain stem. However, data on the rostral spread of morphine-mediated analgesia are sparse. This study examined the rostral spread of analgesic effects on heat and electrical pain after epidural administration of morphine.

Methods: In a randomized, double-blinded, placebo-controlled, crossover study, 5 mg morphine or saline placebo were injected into the lumbar epidural space in nine healthy volunteers. Correct needle placement was confirmed with fluoroscopy. Analgesia to experimental nociceptive heat and electrical stimuli was measured at lumbar (L4), thoracic (T10), cervical (C2), and trigeminal (V2) levels before and 2, 5, 10, and 24 h after epidural injection. Plasma samples for assaying morphine concentrations were drawn before and after each analgesic evaluation.

Results: Epidural morphine significantly attenuated experimental heat pain at all dermatomes tested compared with saline placebo. Analgesic effects were significant at L4 after 2, 5, and 10 h, at T10 after 5, 10, and 24 h, and at V2 after 10 h. Electrical pain was attenuated at the lumbar and thoracic but not at the cervical dermatome. Analgesic effects were significant at L4 after 2, 5, and 10 h and at T10 after 5 and 10 h. Morphine plasma concentrations were below the detection limit (1 ng/ml) in eight of the nine subjects 10 h after epidural injection.     

"Spinolith": case report of a loose body in the spinal canal

STUDY DESIGN: Case report. A hitherto unreported finding of a bony loose body found lying in the spinal canal causing spinal canal stenosis is presented. SUMMARY OF CLINICAL DETAILS: A 68-year-old, fit man presented with a history of progressive neurologic claudication and neurologic deficit in both his lower limbs. Clinical examination revealed excellent range of movements in his lumbar spine and bilaterally normal straight leg raising. He had no significant pain in his back. Neurologic examination showed affection of L5 and S1 dermatomes and myotomes bilaterally. Magnetic resonance imaging scan showed severe localized lumbar spinal stenosis at L4-L5. In the absence of any obvious pathology on the scan, it was presumed that the stenosis was the result of infolding of the redundant ligamentum flavum. His walking distance and neurologic deficit continued to deteriorate, although sphincters were not involved. He underwent a posterior spinal decompression of L4-L5. On performing the laminectomy an ovoid and well-defined pearly white loose body was discovered lying loose in the spinal canal causing stenosis. Histologically, the loose body consisted of trabecular bone with areas of cartilage. The patient made a speedy recovery after surgery and was back to his previous level of activity within a month. DISCUSSION: Several different types of foreign body have been identified in the spinal canal. However, this case of an autologous loose body in the spinal canal causing symptomatic canal stenosis is unique. Because the authors could not identify the source of this loose body, they have termed it "spinolith."     

Direct administration of methotrexate into the central nervous system of primates. Part 2: Distribution of 3H methotrexate after intrathecal lumbar injection.

The kinetics of distribution of 3H methotrexate (3HMTX) in the central nervous system, plasma, and urine after intraventricular, lumbar percutaneous puncture, and spinal catheter injections were compared. Levels of 3HMTX in whole brain after lumbar percutaneous injection were 40 times less than after intraventricular injection. Injection of 3HMTX via a spinal catheter increased the level of 3HMTX in whole brain but this was still tenfold less than after direct intraventricular instillation. Also, it was found that a disproportionately high amount of 3HMTX was in the brain-stem-cerebellum region which would further reduce the concentration of methotrexate in the cerebral hemispheres. Both intraventricular and lumbar spinal catheter administration of 3HMTX produced 3HMTX levels greater than 10(-6)M (moles/kg wet weight) in spinal cord tissue as measured by 3H specific activity between 2 to 8 hours after injection. Administration by lumbar percutaneous puncture, however, rarely resulted in this suggested therapeutic level of 10(-6)M. Initial 3HMTX levels in plasma after lumbar percutaneous instillation was 24 times greater than after intraventricular or lumbar spinal catheter injections. This indicated significant and unavoidable extradural leakage after lumbar percutaneous puncture, which may account for the substantially lower levels of 3HMTX in the brain and spinal cord tissue. It is concluded that intraventricular instillation of methotrexate is the best route of administering the drug to achieve therapeutic levels of methotrexate in both whole brain and throughout the spinal cord.     

Anatomical configuration of the spinal column in the supine position. I. A study using magnetic resonance imaging

In order to clarify the anatomical configuration of the spinal column in the supine position, we have examined T1-weighted sagittal midline magnetic resonance images of the spinal column in 20 healthy volunteers (11 men, nine women) in the supine position. The mean maximum angles of decline of the lumbar spinal canal in men and women were 12.6 (SD 3.9) degrees and 13.4 (3.3) degrees in the cephalad direction, respectively. The maximum angles of incline of the upper thoracic spinal canal in men and women were 20.3 (4.0) degrees and 18.5 (2.5) degrees, respectively. The median highest points of the lumbar spinal canal in men and women were located at L4 (range L3-4 to L4) and L4 (L4), respectively. The lowest point of the thoracic spinal canal was located at T8 (T7-T9) in both men and women. We have demonstrated that both lumbar lordosis and thoracic kyphosis differ between individuals, particularly with respect to the lowest point of the thoracic spinal canal, which is located between T7 and T9.      

Changes in the iliac crest-lumbar relationship from standing to prone.

BACKGROUND CONTEXT: It is known that positioning patients on the Jackson and Andrews operative tables causes changes in lumbar lordosis and pelvic rotation. However, it is unknown if the relationship between the iliac crest and underlying lumbar levels, in particular the L4-L5 interspace, changes from standing to prone on these tables. PURPOSE: To assess the changes in the relationship between the iliac crests and lumbar spinal levels from standing to prone on two different operative positions using the Jackson and Andrews frames. STUDY DESIGN/SETTING: Comparative analysis of iliac crest position relative to spinal levels in the preoperative standing position and while positioned on the Jackson and Andrews frames. PATIENT SAMPLE: 48 randomly selected patients who underwent spinal surgery on either the Jackson or Andrews frame. OUTCOME MEASURES: Imaging. METHOD: Comparative measurements were made of the preoperative and intraoperative plain lateral lumbar radiographs. The location of the superior border of the iliac crest relative to the L4 lumbar spine level was compared between radiographs. RESULTS: Preoperatively, the iliac crest aligned with L4/L4-L5 spinal level in 79.2% of the 48 patients compared with 85.5% of intraoperative cases (p=.59). Intraoperative iliac crest level aligned with the L4/L4-L5 level in 80.8% and 90.9% of the patients on the Andrews and Jackson tables respectively (p=.43). Thirty-four patients (70.8%) demonstrated no change in iliac crest alignment between intraoperative and preoperative radiographs. There was a trend for the iliac crest to shift cephalad with operative positioning. CONCLUSION: Approximately 30% of patients demonstrated changes in the relationship between the iliac crest and lumbar levels between standing and positioning prone. The intraoperative position of the iliac crest aligned more accurately with the L4/L4-L5 spine level on the Jackson and Andrews frame compared with preoperative standing radiographs respectively. Further biomechanical studies should investigate the implication for lumbopelvic fixation.