Dynamic effects on the lumbar spinal canal: axially loaded CT-myelography and MRI in patients with sciatica and/or neurogenic claudication

STUDY DESIGN: In patients with sciatica or neurogenic claudication, the structures in and adjacent to the lumbar spinal canal were observed by computed tomographic myelography or magnetic resonance imaging in psoas-relaxed position and during axial compression in slight extension of the lumbar spine. OBJECTIVES: To determine the mechanical effects on the lumbar spinal canal in a simulated upright position. SUMMARY OF BACKGROUND DATA: For years, functional myelographic investigation techniques were shown to be of value in the evaluation of suspected encroachment of the spinal canal. Since the advent of computed tomography and magnetic resonance imaging, there have been few clinical and experimental attempts that have imitated these techniques. The data indicate that the space within the canal is posture dependent. METHODS: Portable devices for axial loading of the lumbar spine in computed tomographic and magnetic resonance examinations were developed. Fifty patients (94 sites) were studied with computed tomographic myelography, and 34 patients (80 sites) with magnetic resonance in psoas-relaxed position followed by axial compression in slight extension. The dural sac cross-sectional area at L2 to S1, the deformation of the dural sac and the nerve roots, and the changes of the tissues surrounding the canal were observed. RESULTS: In 66 of the investigated 84 patients, there was a statistically significant reduction of the dural sac cross-sectional area in at least one site during axial compression in slight extension. Of the investigated patients, 29 passed the borderlines for relative (100 mm2) or absolute stenosis (75 mm2) in 40 sites. In 30 patients, there was deformation of the dural sac in 46 sites. In 11 of the patients investigated with magnetic resonance imaging, there was a narrowing of the lateral recess in 13 sites, during axial compression in slight extension. CONCLUSIONS: Axial loading of the lumbar spine in computed tomographic scanning and magnetic resonance imaging is recommended in patients with sciatica or neurogenic claudication when the dural sac cross-sectional area at any disc location is below 130 mm2 in conventional psoas-relaxed position and when there is a suspected narrowing of the dural sac or the nerve roots, especially in the ventrolateral part of the spinal canal in psoas-relaxed position. The diagnostic specificity of the spinal stenosis will increase considerably when the patient is subjected to an axial load.     

Spontaneous epidural hematoma as a cause of sciatic pain in a schoolboy

A previously healthy 13-year-old boy began to manifest radiating pain in his left leg after heavy physical exertion during judo training. He also had a sensation of numbness in his left buttock and leg. Initially, the patient was treated conservatively with a clinical diagnosis of disc herniation. However, following 3 months of conservative treatment, there was no relief of pain. Magnetic resonance imaging of the lumbar spine demonstrated an epidural mass causing compression of the dural sac at the L4-L5 disc level. During surgery, the L5 nerve root was found to be severely compressed in the spinal canal because of a chronic epidural hematoma. Following microsurgical removal of this hematoid mass, the patient had a good recovery. Spontaneous epidural hematomas in the lumbar region are rare, and only a few cases presenting with features simulating those caused by a disc herniation have been reported. Our patient represents the first such case described in a child.     

Analysis of failures and poor results of lumbar spine surgery

The failures and poor results of lumbar spine surgery are analyzed in a retrospectively study of 105 consecutive patients referred to the authors for evaluation during 1976. Those who had a history of industrial or vehicular accident outnumbered others by about two to one. Review of histories, physical findings, and myelograms in most of the patients failed to substantiate the diagnosis of ruptured disc or nerve root compression. Many of the failures occurred in thos patients in whom little if any evidence of nerve root compression was found. The indications for surgery were poor in this group. Other failures occurred in patients who had improper, incomplete, or inadequate operations, especially those with lumbar spondylosis, a retained fragment of disc, or surgery at the wrong level. In addition to failure, poor results were recorded in patients who had significant nerve root or cauda equina injury from surgery, associated "arachnoiditis" which is thought to result from surgical trauma in many instances, or multiple operations leading to a hopelessly disabled state.     

A case of idiopathic spinal cord herniation

The authors experienced a case of idiopathic spinal cord herniation with duplicated dura mater. A 63-year-old woman presented right dominant slowly progressive spastic paraplegia and dissociated sensory disturbance. Magnetic resonance imaging (MRI) demonstrated an enlarged dorsal arachnoid space associated with an apparently focally narrowed thoracic cord. The cord was kinked towards the anterior and closely applied to vertebral body at the level of Th3-4. Computed tomographic myelography (CTM) revealed homogeneous filling at dorsal arachnoid space immediately after injection and no defects. At operation multilocular arachnoid cyst and duplicated dura mater was respectively observed dorsally, and ventrally. From defected area of the inner layer, a ventral part of the spinal cord was incarcerated between the two dural layers. After rejection of arachnoid cyst and inner layer was performed, the patient recovered neurologically. Idiopathic spinal cord herniation is a rare disease that shows slowly progressive myelopathy at middle age. The herniations were observed at ventral thoracic cord in all reported cases. The mechanism of this disease is still uncertain. But at least three successive factors seem to be necessary for formation of herniation, 1) abnormal structure of the dura mater such as defect, diverticulum and duplication; 2) adhesion between the cord and the destructive dura mater, and 3) continuous cerebrospinal fluid (CSF) pressure pushing the cord outward from subdural space. In the thoracic spine, mobility is limited compared with the cervical and lumbar spine, and because of physiological curvature the cord situates rather ventrally. For these reasons the incidence of adhesion might be higher at ventral thoracic spine. Although neuroradiological imagings especially MRI and CTM were useful, operative findings were necessary for definitive diagnosis in many reported cases. Considering the effectiveness of surgical treatment, study of the ventral side of the cord should be important to avoid misdiagnosis.     

Attempted experimental modification of the postlaminectomy membrane by local instillation of recombinant tissue-plasminogen activator gel

A prospective, randomized, blinded trial involving 25 adult mongrel dogs was performed to evaluate whether placement of a fat graft or local instillation of recombinant tissue-plasminogen activator gel (rt-PA) could modify the development of a postlaminectomy membrane. One component of the study involved the performance of a lumbar laminectomy and placement of gel rt-PA, free fat, or no tissue placement over the exposed dura mater. Three months later the animals were killed and sections of spine were removed en bloc, decalcified, and examined histologically. No significant differences were found in the degree of cellular fibrosis or heavy collagen production. A similar laminectomy at another lumbar level was also followed by gel rt-PA, free fat, or no tissue placement. Three months after surgery, surgery was performed again at this level immediately before death. There were no differences in the adhesiveness of the laminectomy membrane to dura mater or roots. It was concluded that the local instillation of gel rt-PA after laminectomy did not inhibit scar formation or scar adherence to the dura mater.     

Dural tears secondary to operations on the lumbar spine. Management and results after a two-year-minimum follow-up of eighty-eight patients

We reviewed the results of acute management of patients who had sustained a dural tear during an operation on the lumbar spine, and we attempted to determine the long-term sequelae of this complication. In the five years from July 1989 to July 1994, 641 consecutive patients had a decompression of the lumbar spine, performed by the senior one of us; of these patients, eighty-eight (14 percent) sustained a dural tear, which was repaired during the operation. The duration of follow-up ranged from two to eight years (average, 4.3 years). Postoperative management consisted of closed suction wound drainage for an average of 2.1 days and bed rest for an average of 2.9 days. Of the eighty-eight procedures that resulted in a dural tear, forty-five were revisions; these revisions were performed after an average of 2.2 previous operations on the lumbar spine, all of which resulted in a scar adherent to the dura. Only eight patients had headaches related to the spinal procedure and photophobia in the postoperative period; these symptoms resolved in all but two patients, both of whom had had a revision operation. Each of the two patients had symptoms of a persistent leak of spinal fluid and needed a reoperation for repair. Overall, seventy-six patients had a good or excellent result and twelve had a poor or satisfactory result with some residual back pain. One patient had arachnoiditis, and another had symptoms of viral meningitis one month postoperatively. A dural tear that occurs during an operation on the lumbar spine can be treated successfully with primary repair followed by bed rest. Such a tear does not appear to have any long-term deleterious effects or to increase the risk of postoperative infection, neural damage, or arachnoiditis. Closed suction wound drainage does not seem to aggravate the leak and can be used safely in the presence of a dural repair.     

Advanced nursing roles: their worth in nursing

The suitability of the cerebrospinal fluid (CSF) in the lumbosacral dural sac as an internal signal-intensity reference was studied on magnetic resonance imaging (MRI) of the lumbar spine using a surface coil and motion artefact suppression technique. A signal-intensity reference is needed when signal is compared between images, studies or subjects. Homogeneity of the CSF was estimated visually on T2-weighted images of 60 subjects at 1.5 T and of another 60 subjects at 0.1 T. Spines with a severely narrowed dural sac or marked scoliosis were excluded from the study to avoid partial volume effect. CSF was homogeneous in 82% and 73% of the examinations at 1.5 T and 0.1 T, respectively. The type and location of the local inhomogeneities did not relate to local narrowings of the dural sac. The signal intensity of CSF was measured in 108 examinations at 0.1 T after correcting the spatially-dependent signal-intensity non-uniformities with a phantom-based method. The signal-intensity difference between the CSF in the upper and lower lumbar dural sac was less than 10% in 73% of the examinations. The CSF in the lumbosacral dural sac can be a useful signal-intensity reference for estimation of the signal of the adjacent structures in patients without severe narrowing of the dural sac or marked scoliosis. It may contribute to assessing spinal disease processes.     

Anatomic relations of the thoracic pedicle to the adjacent neural structures

STUDY DESIGN: This study analyzed anatomic parameters between the thoracic pedicles and the spinal nerve roots. OBJECTIVES: To quantitatively determine the anatomic relations of the thoracic pedicle to the adjacent neural structures. SUMMARY OF BACKGROUND DATA: Pedicular screw placement carries with it potential hazard to the surrounding neural structures, especially in the thoracic spine. No studies exist regarding the anatomic relations of the thoracic pedicle to the adjacent nerve roots. METHODS: Fifteen cadavers were obtained for study of the thoracic spine. All soft tissue was dissected off the thoracic spine. Laminectomy and total removal of the superior and inferior articular facets was then performed on C7-T1 through T12-L1 to expose the pedicles, nerve roots, and dura. Measurements were taken from the pedicle to the nerve root superiorly and inferiorly as well as between the pedicles. Also, the superoinferior diameter of the nerve root and the frontal angle of the nerve root were measured. Symmetrical structures were measured bilaterally. RESULTS: The results showed that no epidural space could be found between the dural sac and the pedicle in all 15 cadavers. The average distances from the thoracic pedicle to the adjacent nerve roots superiorly or inferiorly at all levels ranged from 1.9 to 3.9 mm and from 1.7 to 2.8 mm, with a minimum of 1.3 mm, respectively. The interpedicular distance increased from T1 (13.8 mm) to T3, slightly decreased in T4-T5, then gradually increased to T12 (16.6 mm). The superoinferior diameter of the nerve root increased consistently from 2.9 mm at T1 to 4.6 mm at T11. The frontal nerve root angle decreased consistently from T1 (120.1 degrees) to T12 (57.1 degrees), except at T4-T5. CONCLUSIONS: This study suggested that more care be taken into consideration in placing a transpedicular screw in the transverse plane than in placing a screw in the sagittal plane in the thoracic spine.     

Middle fossa decompression of the trigeminal sensory root for trigeminal neuralgia--a re-appraisal and a modification of the technique

Twenty-three patients with intractable trigeminal neuralgia were treated by a modified technique of middle fossa extradural decompression of the trigeminal sensory root at the petrous ridge. After exposing the ganglion and the root at the petrous ridge, by an extradural Frazier's approach a thin layer of autogenous fat was interposed between the dura propria and the middle fossa dura anteriorly, and between the petrous ridge and the root posteriorly. The fat layers were used to prevent dural adhesions and to maintain a space between the petrous ridge and the root. The dura propria was preserved intact. All patients obtained immediate relief of pain following surgery. Twenty patients continue to remain pain free. Two patients have mild occasional pains and one has a persistent pain of moderate intensity. One patient developed a dense sensory loss and two had delayed facial weakness which recovered completely within a month. The mechanism of trigeminal neuralgia is discussed on the basis of anatomical, histopathological and electrophysiological findings and the rationale of middle fossa decompression of the root is stressed. This method is short, simple and safe and may serve as an alternative to the more recent methods of treating trigeminal neuralgia.     

Meningovertebral ligaments and their putative significance in low back pain

OBJECTIVE: To determine the presence and morphology of the meningovertebral ligaments (ligaments of Hofmann) as well as postulate their possible contribution to low back pain. DESIGN: Sagittal dissections were performed on 12 embalmed cadaver specimens including the L5/S1 intervertebral level cephalad to T1. Meningovertebral ligaments were labeled and documented in both the lumbar and thoracic regions. RESULTS: Meningovertebral ligaments were found in both the lumbar and thoracic regions of all cadaveric specimens. These ligaments were much more prevalent in the lumbar vertebral column but were also present throughout the thoracic vertebral column. The meningovertebral ligaments in the lumbar region were more robust as well as more frequently encountered than those found in the thoracic region. CONCLUSION: Dural sac attachments to the posterior aspect of the vertebral bodies and the posterior longitudinal ligament could act to traction the dural sac in the event of nuclear bulge or herniation. The prevalence of these ligaments in the lumbar spine, coupled with the high incidence of herniated nucleus pulposus and disc bulges in this region, may compound the effects of disc pathology and result in increased low back pain.     

Effect of source of iron on duodenal absorption of iron, calcium, phosphorous, magnesium, copper and zinc in rats with ferropoenic anaemia

The purpose of this study was to undertake a critical review of the potential role of magnetic resonance imaging (MRI) in the evaluation of low back pain (LBP) and to determine if there were differences in the MRI appearances between various occupational groups. The study group, 149 working men (78 aged 20-30 years and 71 aged 31-58 years) from five different occupations (car production workers, ambulance men, office staff, hospital porters and brewery draymen), underwent MRI of the lumbar spine. Thirty-four percent of the subjects had never experienced LBP. Twelve months later, the examination was repeated on 89 men. Age-related differences were seen in the MRI appearances of the lumbar spine. Disc degeneration was most common at L5/S1 and was significantly more prevalent (P < 0.01) in the older age group (52%) than in the younger age group (27%). Although LBP was more prevalent in the older subjects there was no relationship between LBP and disc degeneration. No differences in the MRI appearance of the lumbar spine were observed between the five occupational groups. Overall, 45% had 'abnormal' lumbar spines (evidence of disc degeneration, disc bulging or protrusion, facet hypertrophy, or nerve root compression). There was not a clear relationship between the MRI appearance of the lumbar spine and LBP. Thirty-two percent of asymptomatic subjects had 'abnormal' lumbar spines and 47% of all the subjects who had experienced LBP had 'normal' lumbar spines. During the 12-month follow-up period, 13 subjects experienced LBP for the first time. However, there was no change in the MRI appearances of their lumbar spines that could account for the onset of LBP. Although MRI is an excellent technique for evaluating the lumbar spine, this study shows that it does not provide a suitable pre-employment screening technique capable of identifying those at risk of LBP.     

Acquired dural arteriovenous malformations of the lumbar spine: case report

OBJECTIVE AND IMPORTANCE: Although dural arteriovenous malformations (AVMs) are considered to be acquired, no conclusive evidence has been obtained. The first case of dural AVMs of the lumbar spine that showed evidence supporting their being acquired lesions is described. CLINICAL PRESENTATION: A 27-year-old man was admitted to our hospital in November 1994, presenting with increasing pain and numbness in the left buttock to the left lower limb. Myelography and arteriography showed dural AVMs of the lumbar spine. However, the myelogram obtained before surgery for lumbar disc herniation in 1987 provided no findings suggestive of intradural vascular anomalies. INTERVENTION: Embolization procedures via the left iliolumbar arteries were performed. However, there was no improvement of the symptoms, and the patient underwent surgical treatment. CONCLUSION: The present report documents a case of dural AVMs of the lumbar spine that showed evidence supporting their being acquired lesions.     

Sensory nerve fibres from lumbar intervertebral discs pass through rami communicantes. A possible pathway for discogenic low back pain

It has been thought that lumbar intervertebral discs were innervated segmentally. We have previously shown that the L5-L6 intervertebral disc in the rat is innervated bilaterally from the L1 and L2 dorsal root ganglia through the paravertebral sympathetic trunks, but the pathways between the disc and the paravertebral sympathetic trunks were unknown. We have now studied the spines of 17 rats to elucidate the exact pathways. We examined serial sections of the lumbar spine using immunohistochemistry for calcitonin gene-related peptide, a sensory nerve marker. We showed that these nerve fibres from the intervertebral disc ran through the sinuvertebral nerve into the rami communicantes, not into the corresponding segmental spinal nerve. In the rat, sensory information from the lumbar intervertebral discs is conducted through rami communicantes. If this innervation pattern applies to man, simple decompression of the corresponding nerve root will not relieve discogenic pain. Anterior interbody fusion, with the denervation of rami communicantes, may be effective for such low back pain.     

Lumbar spine magnetic resonance imaging: comparison between fast spin echo proton density and spin echo T1 axial scans

Spin echo (SE) T1 axial scans are routinely obtained in magnetic resonance imaging of the lumbar spine in many centres. This study directly compared matched SE T1 and fast SE (FSE) proton density (PD) axial scans. Both SE T1 and FSE PD axial scans of the lumbar spine were obtained in 116 consecutive patients. The imaging parameters (field-of-view, slice thickness, interslice gap, number of excitations and matrix size) and scan levels were identical for each pair of sequences. At two selected levels, L4/5 and L5/S1, various structures were independently graded by two observers. In 232 lumbar levels analysed, the bone marrow, epidural fat, disc, extradural nerve root and facet joint were equally well seen on both sequences by both observers (combined mean grades of 2.93-2.99). The thecal sac was marginally better depicted on FSE PD than on SE T1 images, with mean grades of 2.96 and 2.88, respectively. The psoas muscle was adequately visualized for diagnostic purposes on both sequences (mean grades of 2.30-2.32). The cauda equina were better seen on FSE PD (mean grade 1.92) than on SE T1 (mean grade 1.00) images. In conclusion, FSE PD scans are comparable to and may potentially replace SE T1 axial MR scans of the lumbar spine.     

Lumbar disk prolapse surgery with or without free fat transplantation. A prospective triple-blind randomized study

The aim of this prospective triple-blind randomized study was to determine if a free fat transplant used in operation in lumbar disc herniation could reduce the degree of intraspinal scar tissue and to evaluate whether the scar tissue could lead to symptoms. Ninety-nine patients were subsequently examined after median 376 days. The clinical outcome was scored using the Low Back Pain Rating Scale. Enhanced CT-scanning was assessed regarding the degree of scar tissue and survival of the fat transplant. There was no difference in the clinical outcome between the two groups. Significantly fewer had dural scarring in the group who had a free fat transplantation, but there was no difference regarding the degree of radicular scarring. The transplant was shown on CT-scan at the follow-up examination in 66% of the patients who had a fat transplantation. Free fat transplantation can reduce the degree of dural scar tissue after operation for lumbal disc herniation, but does not result in a clinically better outcome.     

Posterior fossa decompression without duraplasty in infants and young children for treatment of Chiari malformation and achondroplasia

Some children with Chiari malformation and achondroplasia require posterior fossa decompression that typically includes expansion of the dural tube with duraplasty. Infants and young children, however, may have a more distensible dura mater than do older patients. Furthermore, the structures that compress the hindbrain of young patients may be the bone and abnormally thickened atlantooccipital membrane, i.e., dural band, rather than the dura mater. We have treated 7 children who had Chiari malformation or achondroplasia with posterior fossa decompression without duraplasty. All children were symptomatic; 3 had Chiari-I malformations, 2 Chiari-II malformations, and 2 achondroplasia. The age range was 3 months to 2.5 years (mean 15.1 months). The exent of tonsillar herniation and other hindbrain anomalies was assessed on preoperative magnetic resonance imaging. The infants with Chiari-II malformations underwent cervical laminectomies, whereas the other young children with Chiari-I malformations or achondroplasia underwent suboccipital craniectomy as well as cervical laminectomy. In Chiari malformation, the dural band was divided; in achondroplasia, there was no identifiable dural band. Following bony decompression and division of the identifiable dural band, immediate expansion of the stenotic region with visible cerebrospinal fluid space posterior to the neural elements could be ascertained by intraoperative ultrasonography. During a follow-up period ranging from 4.5 months to 4 years (mean 22 months), all patients made improvements in their symptoms, 3 having complete resolution of their symptoms. This preliminary experience indicates that in children 2 years of age or younger, posterior fossa bony decompression without duraplasty can be effective treatment for Chiari malformations or achondroplasia.     

Groin pain associated with lower lumbar disc herniation

STUDY DESIGN: Retrospective clinical and magnetic resonance imaging study of patients with groin pain associated with lower lumbar disc herniation. OBJECTIVES: To demonstrate the clinical features and magnetic resonance imaging findings of these patients. SUMMARY OF BACKGROUND DATA: Patients with lumbar disc herniation sometimes report groin pain. Little mention has been made, however, regarding the clinical features of groin pain stemmed from lower lumbar disc herniation until now, with only Murphey referring to groin pain in disc disease. METHODS: A total of 512 patients were diagnosed with singular lower lumbar disc herniation (L4-L5 and L5-S1) at Kakegawa City General Hospital between July 1990 and December 1993. Of these patients, 21 (4.1%) reported groin pain. The characteristic clinical features and magnetic resonance imaging findings of the 21 patients were investigated and compared with the features and findings of patients with no groin pain. RESULTS: Patients with groin pain had a higher mean age and lower rate of low back pain, and L4-L5 discs were more likely to be involved than L5-S1 discs. In their magnetic resonance images, herniation tended to be more central than in patients with no groin pain. CONCLUSIONS: Elderly patients with L4-L5 protruding herniation of the anulus fibrosus were most likely to experience groin pain. The sinuvertebral nerve that innervates the posterior anulus fibrosus, the posterior longitudinal ligament, and the dura was indicated as the afferent nerve of groin pain.     

Atraucan: a new needle for spinal anesthesia

BACKGROUND AND OBJECTIVES: Atraucan 26-gauge spinal needles have a tip designed to make a small linear cut (as opposed to a V-shaped cut) in the dura mater. The cut is shorter than the outside diameter of the needle and is dilated as the needle passes through the dura. The needle is used with a 20-gauge introducer. In vitro, it causes less leakage of cerebrospinal fluid than Quincke 26-gauge or Sprotte 24-gauge needles. This study was designed to test the ease of use and any damage caused to the needle tip during lumbar dural puncture. METHODS: This was a multicenter trial (six centers in five countries) involving 362 patients undergoing spinal anesthesia. A detailed questionnaire was filled in for every patient by the anesthesiologist. All the needles were returned to the factory and examined microscopically for damage. RESULTS: Lumbar dural puncture was successful in all but one patient. Spinal anesthesia was satisfactory for the planned surgery in 97%. Microscopy of the needle tips showed only a minor degree (0.01-0.19 mm) of bending in 14%, and none of the tips had a "hook." Postdural puncture headache (PDPH) occurred in nine patients (2.5%), all but one of whom (a 15-year-old male) were females under 55 years of age. CONCLUSIONS: The Atraucan needle is easy to use and has a high success rate in identifying the subarachnoid space. Lumbar dural puncture causes minimal damage to the tip. The incidence of PDPH is low, but a larger comparative study needs to be performed.     

Human dura mater as a wrapping material for hydroxyapatite implantation in the anophthalmic socket

Homologous sclera and autologous fascia lata have been accepted as common wrapping materials for hydroxyapatite implantation; however, various problems have been observed, such as the risk of transmittable diseases such as AIDS or hepatitis. This report details the use of cadaver dura mater to wrap hydroxyapatite implants. For 73 eyes of 73 patients with hydroxyapatite implantation, cadaver dura mater was used to wrap the hydroxyapatite after enucleation or secondary implantation. Of the 73 patients, 20 had conjunctival erosion; however, all of the patients but 1 healed spontaneously within an average of 22 days. Only 1 of the 73 patients progressed to implant exposure requiring a dermis graft. The authors suggest that cadaver dura mater is a suitable wrapping material for hydroxyapatite implantation.