Evaluation of tenoxicam on prevention of arachnoiditis in rat laminectomy model

Post laminectomy arachnoiditis has been shown by experiments with rats and post operative radiological imaging in humans. The purpose of this experimental study was to determine the efficacy of tenoxicam in preventing arachnoiditis in rats. Twenty-four Wistar rats were divided into two groups, and L3 laminectomy was performed. In the tenoxicam group, 0.5 mg/kg tenoxicam was applied intraperitoneally. Normal saline was applied intraperitoneally in the control group. Later, the rats were killed at weeks 3 and 6, and the laminectomy sites were evaluated pathologically for arachnoiditis. The results showed that 6 weeks after surgery, the tenoxicam group showed lowest arachnoiditis grades. However, statistically significant difference was not found in arachnoiditis between the control group and the tenoxicam group. Based on these findings it is concluded that application of the tenoxicam after lumbar laminectomy did not effectively reduce arachnoiditis. Performing the most effective surgical technique without damage around tissue in a small surgical wound and having meticulous hemostasis in surgery seem to be the key for preventing arachnoiditis effectively.

Prevention of arachnoiditis and postoperative tethering of the spinal cord with Gore-Tex surgical membrane: an experimental study with rats

OBJECTIVE

Arachnoidal adhesions and inflammation were evaluated in 72 rats after spinal dural repair with one of three materials, i.e., Gore-Tex surgical membrane, collagen-coated Vicryl mesh, or lyophilized spinal dural allograft.

METHODS

Laminectomy at L1 was performed, and then a 3- x 4-mm segment of spinal dura mater and arachnoid membrane was excised. After implantation of the dural substitute, the animals were divided into normal and injured groups. In the injured group, a spinal cord injury was produced at the midpoint of the duraplasty site by the clip compression technique, with 25-g force for 1 minute. Neurological performance was assessed by the inclined plane technique, and groups of rats were killed at 8 to 24 weeks after surgery. The spinal column was removed en bloc and processed for histological examination.

RESULTS

There were no differences in neurological function among the three dural substitutes in either injured or noninjured rats. However, there were major differences among the groups in the incidence and severity of arachnoid adhesions and tethering. The neural tissue was bound to a thick neomembrane surrounding the lyophilized dural allograft and the collagen-coated Vicryl mesh. In contrast, the Gore-Tex surgical membrane induced only a thin membranous adhesion, which was loose and flexible. The inflammatory and foreign body response was most pronounced in rats treated with collagen-coated Vicryl mesh, at 8 and 24 weeks.

CONCLUSION

In the present study, Gore-Tex surgical membrane was a very good material for the surgical repair of spinal dural defects. Additional experimental studies are required to compare Gore-Tex membrane with autologous tissues.

The effect of urokinase in preventing the formation of epidural fibrosis and/or leptomeningeal arachnoiditis

BACKGROUND

Epidural fibrosis and leptomeningeal adhesion formation are among the common causes of failed back surgery syndrome. Urokinase has been commonly used in treating aneurysmal subarachnoid hemorrhage and intracerebral hematoma.

METHODS

In a rat model, the potential of local urokinase in preventing the production of epidural fibrosis due to bleeding was investigated.

RESULTS

A reduction of approximately 48% in leptomeningeal adhesion formation with the use of urokinase was demonstrated. Adhesion score was 2.300 in the control group and 0.700 in the urokinase treated group on day 42 of the postoperative period.

CONCLUSIONS

It can be concluded that urokinase has the important effect of preventing the formation of leptomeningeal adhesion, but many more extensive studies clearly need to be done before such material can be clinically used.

Peroperative prednisolone fails to improve the clinical outcome following surgery for prolapsed lumbar intervertebral disc. A randomized controlled trial

Ninety three patients undergoing their first conventional hemilaminectomy for lumbar disc protusion were randomized to a double blind clinical trial. Half of the patients were treated immediately following surgery with prednisolone; 50 mg per day for fourteen days and then 25 mg per day for another 14 days. The other patients were treated for the same time period with placebo tablets. Assessments using subjective and objective outcome criteria at 26 weeks, 52 weeks and 156 weeks of follow-up, demonstrated no statistically significant differences between the randomized groups. It is concluded that systemic prednisolone administration in the pre- and postoperative period does not in this study improve the clinical outcome after first time lumbar discectomy.

Effects of laminectomy and retained extradural foreign body on cauda equina adhesion

The histologic effects of posterior lumbar surgery and retained extradural foreign bodies on the cauda equina were investigated in rats over time. The following four groups of rats were provided: Group 1, sham operation (laminar exposure alone); Group 2, laminectomy alone; Group 3, laminectomy with retained extradural silk thread; Group 4, laminectomy with extradural kaolin; and the control. Histological study was performed on the transverse sections of laminectomized (L5) and nonlaminectomized (L4) areas. In Group 1, adhesive changes involving the cauda equina, consisting of dilatation of nutrient vessels, and eosinophilic exudative changes between the adhering cauda rootlets were seen the day after surgery, but the fibrinous adhesion was resolved spontaneously in all rats after 1 week without permanent sequelae. In Groups 2 and 3, postoperative adhesion of the cauda equina roots was conspicuous, but it resolved by 6 weeks. In Group 4, obvious adhesion persisted through the 12th week after surgery. Destruction of the myelin sheath and axonal loss of the cauda equina occurred in the first week after surgery in all the experimental groups except in the sham group. The severity and extent of the neural degeneration were mostly parallel to the severity of inflammatory changes in the epidural areas. At the nonlaminectomized area (L4) in each group, the arachnoid and cauda equina tended to congregate the day after surgery, but these changes were all transitory. The severity and persistency of the arachnoiditis and neural degeneration directly corresponded to the magnitude of the inflammation and wound healing processes. This seems to imply that careful surgical intervention with no use of foreign bodies is necessary to reduce postoperative adhesive arachnoiditis.

A pilot investigation of poloxamer 407 for the prevention of leptomeningeal adhesions in the rabbit

Leptomeningeal adhesion formation frequently complicates operations and diseases of the central nervous system. Chronic adhesive arachnoiditis may follow intraspinal surgery for disc, tumor, and closure of myelomeningocele, eventually producing pain and declining neurological status of the patient. Reoperation for scar removal is seldom successful as the arachnoidal adhesions reform. Poloxamer 407 (P407) has been shown to reduce postoperative peritoneal adhesion formation in rats and golden hamsters. In a rabbit model, we investigated the potential of P407 to prevent the production of arachnoidal adhesions and nerve root scarring following laminectomy and surgical meningeal injury. The lumbar spinal roots of 8 New Zealand white rabbits were surgically isolated under magnification. One root sleeve axilla was opened and immediately closed with 10-0 suture (control site) and a second root sleeve axilla was opened, P407 injected, and closed with 10-0 suture (treatment site). Five of 7 rabbits treated with P407 and followed for 7-42 days showed no arachnoidal adhesions at the level of the nerve root. Four New Zealand white rabbits had the lamina removed, and the dura over the spinal cord was opened at two sites separated by one to two lumbar segments. At one site P407 was inserted beneath the dura following durotomy, and the other site was opened in a similar fashion and immediately closed without the insertion of P407. There was a 50% reduction in leptomeningeal adhesion formation with the use of P407. P407 may be useful in neurosurgery for the prevention of arachnoidal adhesions.

The effect of omental pedicle graft transfer on spinal microcirculation and laminectomy membrane formation

The properties of the omentum and its effect on spinal neurologic disease was investigated. Omental pedicle grafts were transferred to the laminectomized lumbar spines of nine neurologically normal dogs. Grafts were placed on either the dura or the spinal cord. Interruption of the graft's circulation was examined. To study the effect, the artery of the graft was injected with contrast and the graft-dura interface studied histologically. All injected specimens demonstrated vascular connections from the graft to the neural elements. The graft was found to decrease postoperative perineural scarring. The omentum appears to possess properties that could be applied to improve outcomes in spinal surgery.

Surgical considerations in the initial repair of meningomyelocele and the introduction of a technical modification

Tethering of the spinal cord has been increasingly recognized as a cause of late deterioration in the child with repaired meningomyelocele. Findings at reoperation include dense arachnoiditis, dermal inclusion cysts, fibrolipoma of the filum terminale, and, on occasion, foreign body granulomas. This article reviews four key steps in meningomyelocele repair and the guidelines for detection of surgically remediable lesions associated with this disorder. In addition, it proposes a modification of the standard dural closure that may reduce the incidence of contributory adhesive arachnoiditis by the creation of a capacious cerebrospinal fluid space about the neural plaque.

The effect of hydration on the acute and chronic complications of aqueous myelography. An experimental study

The effect of hydration on the incidence of complications from myelography with aqueous media was studied. Myelography was performed with methylglucamine iocarmate in dehydrated and vigorously hydrated monkeys. The incidence of seizures and the severity of arachnoiditis were significantly greater in the dehydrated animals. The authors suggest that patients be permitted fluids ad lib. prior to myelography with aqueous media, or in some cases be given fluids intravenously.

Ineffectiveness of prophylactic intrathecal methylprednisolone in myelography with aqueous media

The effectiveness of prophylactic intrathecal methylprednisone (MP) in preventing arachnoiditis from iocarmate myelography was studied. Monkeys were injected intrathecally with locarmate, MP, or a combination of the two. Twelve weeks later the severity of arachnoiditis was determined in each animal. There was no significant prophylactic effect of intrathecal MP on arachnoiditis from locarmate. Some arachnoiditis was found in control animals treated with MP alone.

Arachnoiditis from experimental myelography with aqueous contrast media

Myelography was performed on 80 monkeys to study postmyelographic arachnoiditis. Metrizamide myelography caused arachnoiditis when high concentrations were used, but not with the usual clinical concentrations. Arachnoiditis resulted after myelography with meglumine iocarmate; however, the risk of arachnoiditis was reduced by diluting the contrast medium. Prophylactic intrathecal methylprednisolone was not effective in preventing arachnoiditis. Blood in the cerebrospinal fluid did not affect the degree of arachnoiditis.

The postoperative myelogram. Radiographic evaluation of arachnoiditis and dural/arachnoidal tears

Either arachnoriditis or dural/arachnoidal tears may cause symptoms in the postoperative spinal patient. Surgery and myelography as causes of arachnoiditis are discussed. Intradural arachnoid cyst formation and intramedullary cavitation may present as unusual sequelae of arachnoiditis. Extra-dural cysts and cerebrospinal fluid fistulas resulting from dural/arachnoidal tears are unusual postoperative complications presenting striking myelographic features. Their mechanisms of formation, clinical significance, and radiographic features are discussed.

Chronic arachnoiditis after a pantopaque study of the posterior fossa

Reported is a case in which chronic arachnoiditis resulted as a complication of using Pantopaque in studying the posterior fossa. The possibility that prophylactic intrathecal injections of methylprednisolone acetate while performing Pantopaque myelography help avoid serious complications is discussed.