Percutaneous cervical cordotomy for chest wall pain from mesothelioma in the setting of neuromyelitis

A 75-year-old man presented to our Interventional Cancer Pain service for consideration of a percutaneous cervical cordotomy (PCC) to control severe chest wall pain secondary to malignant mesothelioma. His medical history included a neuroinflammatory disorder, neuromyelitis optica, for which he had previously had a prolonged hospital admission, with ongoing neurological deficit. Little information is available regarding the safety of PCC in a patient with this condition, specifically the risk of neurological relapse, and we were initially wary about going ahead. After discussion with the patient's neurology team and other UK experts and with the patient's informed consent, we proceeded to PCC with additional steroid cover. No adverse neurological symptoms were encountered perioperatively or postoperatively and the patient had an excellent analgesic result. As this combination of circumstances has not to our knowledge been documented, we wished to present this case and discuss the factors affecting our decision and management.

Cervical Cordotomy for Intractable Pain: Do Postoperative Imaging Features Correlate with Pain Outcomes and Mirror Pain?

BACKGROUND AND PURPOSE

Percutaneous cervical cordotomy offers relief of unilateral intractable oncologic pain. We aimed to find anatomic and postoperative imaging features that may correlate with clinical outcomes, including pain relief and postoperative contralateral pain.

MATERIALS AND METHODS

We prospectively followed 15 patients with cancer who underwent cervical cordotomy for intractable pain during 2018 and 2019 and underwent preoperative and up to 1-month postoperative cervical MR imaging. Lesion volume and diameter were measured on T2-weighted imaging and diffusion tensor imaging (DTI). Lesion mean diffusivity and fractional anisotropy values were extracted. Pain improvement up to 1 month after surgery was assessed by the Numeric Rating Scale and Brief Pain Inventory.

RESULTS

All patients reported pain relief from 8 (7-10) to 0 (0-4) immediately after surgery (P = .001), and 5 patients (33%) developed contralateral pain. The minimal percentages of the cord lesion volume required for pain relief were 10.0% on T2-weighted imaging and 6.2% on DTI. Smaller lesions on DWI correlated with pain improvement on the Brief Pain Inventory scale (r = 0.705, P = .023). Mean diffusivity and fractional anisotropy were significantly lower in the ablated tissue than contralateral nonlesioned tissue (P = .003 and P = .001, respectively), compatible with acute-phase tissue changes after injury. Minimal postoperative mean diffusivity values correlated with an improvement of Brief Pain Inventory severity scores (r = -0.821, P = .004). The average lesion mean diffusivity was lower among patients with postoperative contralateral pain (P = .037).

CONCLUSIONS

Although a minimal ablation size is required during cordotomy, larger lesions do not indicate better outcomes. DWI metrics changes represent tissue damage after ablation and may correlate with pain outcomes.

Spinal signalling of C-fiber mediated pleasant touch in humans

C-tactile afferents form a distinct channel that encodes pleasant tactile stimulation. Prevailing views indicate they project, as with other unmyelinated afferents, in lamina I-spinothalamic pathways. However, we found that spinothalamic ablation in humans, whilst profoundly impairing pain, temperature and itch, had no effect on pleasant touch perception. Only discriminative touch deficits were seen. These findings preclude privileged C-tactile-lamina I-spinothalamic projections and imply integrated hedonic and discriminative spinal processing from the body.

Exercise modulates chloride homeostasis after spinal cord injury

Activity-based therapies are routinely integrated in spinal cord injury (SCI) rehabilitation programs because they result in a reduction of hyperreflexia and spasticity. However, the mechanisms by which exercise regulates activity in spinal pathways to reduce spasticity and improve functional recovery are poorly understood. Persisting alterations in the action of GABA on postsynaptic targets is a signature of CNS injuries, including SCI. The action of GABA depends on the intracellular chloride concentration, which is determined largely by the expression of two cation-chloride cotransporters (CCCs), KCC2 and NKCC1, which serve as chloride exporters and importers, respectively. We hypothesized that the reduction in hyperreflexia with exercise after SCI relies on a return to chloride homeostasis. Sprague Dawley rats received a spinal cord transection at T12 and were assigned to SCI-7d, SCI-14d, SCI-14d+exercise, SCI-28d, SCI-28d+exercise, or SCI-56d groups. During a terminal experiment, H-reflexes were recorded from interosseus muscles after stimulation of the tibial nerve and the low-frequency-dependent depression (FDD) was assessed. We provide evidence that exercise returns spinal excitability and levels of KCC2 and NKCC1 toward normal levels in the lumbar spinal cord. Acutely altering chloride extrusion using the KCC2 blocker DIOA masked the effect of exercise on FDD, whereas blocking NKCC1 with bumetanide returned FDD toward intact levels after SCI. Our results indicate that exercise contributes to reflex recovery and restoration of endogenous inhibition through a return to chloride homeostasis after SCI. This lends support for CCCs as part of a pathway that could be manipulated to improve functional recovery when combined with rehabilitation programs.

[Lampreys as an animal model in regeneration studies after spinal cord injury]

Spinal cord injuries are an important sanitary and economical problem for the society. In mammals, including humans, a traumatic injury to the spinal cord leads to a loss of motor and sensorial function, which is irreversible due to the low regenerative ability of the central nervous system. In contrast to mammals, functional recovery occurs spontaneously after a complete spinal cord transection in lampreys. Functional recovery occurs because in these animals about 50% of the reticulospinal axons regenerate after injury and also because of the occurrence of processes of reorganization and plasticity of the spinal circuits. In this review, we first analyze the characteristics and regeneration ability of lampreys as compared to mammals. Then, we compile the knowledge about the process of recovery after a spinal cord injury acquired in studies using the lampreys as animal model and finally we provide some general perspectives about the molecular processes implicated in regeneration that can be investigated in a very advantageous way in this animal model and which knowledge could allow to develop new therapies for patients suffering spinal cord injury.

Kyphectomy in children with myelomeningocele

BACKGROUND

Patients with myelomeningocele and rigid lumbar and thoracolumbar kyphosis face substantial functional difficulties with sitting and lying supine and are prone to skin breakdown over the gibbus and risk of infection. Kyphectomy, along with cordotomy and segmental spinal instrumentation down to the pelvis, is one alternative that can provide reliable correction of the deformity but also can maintain that correction over a period of time.

QUESTIONS/PURPOSES

We determined the fusion rates, deformity correction and maintenance, and perioperative complications of kyphectomy with long segmental spinal instrumentation using the Warner and Fackler technique.

METHODS

We retrospectively reviewed the charts and radiographs of 33 patients with myelomeningocele who had kyphectomy with segmental spinal instrumentation down to the pelvis between 1991 and 2006. The average age at surgery was 7.6 years (range, 3-19 years). Twenty-one patients had a minimum 2-year followup (average, 7.0 years; range, 2.4-15.7 years).

RESULTS

The average preoperative kyphosis of 124° (range, 75°-210°) improved at last followup to 22° (range, 3°-55°) with an average correction of 81% (range, 59%-98%). We identified 17 postoperative complications. Wound and skin complications were most common; 11 secondary surgeries were performed in 10 patients.

CONCLUSIONS

Surgery for myelomeningocele kyphosis is technically demanding and carries substantial risk. Kyphectomy and posterior spinal fusion and instrumentation with the Warner and Fackler technique allow correction and maintenance of sagittal alignment.

Origins of endomorphin-2 immunopositive fibers and terminals in the spinal dorsal horn of the rat

Endomorphin 2 (EM2) plays essential roles in regulating nociceptive transmission within the spinal dorsal horn, where EM2-immunopositive (EM2-IP) fibers and terminals are densely encountered. However, the origins of these EM2-IP structures are still obscure. Unilateral primary sensory afferents disruption (lumbar 3-6 dorsal roots rhizotomy) significantly decreased the density of EM2-IP fibers and terminals in the superficial laminae (laminae I and II) on the ipsilateral but not contralateral lumbar dorsal horn (LDH). Spinal hemisection at the 7th thoracic (T7) segment down-regulated bilateral EM2 expression, with a higher influence on the ipsilateral side of the LDH. Unilateral L3-6 dorsal roots rhizotomy combined with spinal transection but not with hemisection at T7 level completely obliterated EM2-IP fibers and terminals on the rhizotomized-side of the LDH. Disruption of bilateral (exposure to the primary afferent neurotoxin, capsaicin) primary sensory afferents combined with spinal hemisection at T7 decreased the EM2-IP density bilaterally but could obliterate it on neither side of the LDH. While in capsaicin plus transection rats, EM2 was depleted symmetrically and completely. In the colchicine treated rats, no EM2-IP neuronal cell bodies could be detected in the spinal gray matter. After injecting tetramethyl rhodamine dextran-amine (TMR) into the LDH, some of the TMR retrogradely labeled neurons in the nucleus tractus solitarii (NTS) showed EM2-immunoreactivities. The present results indicate that EM2-IP fibers and terminals in the spinal dorsal horn originate from the ipsilateral primary afferents and bilateral descending fibers from NTS.

Bilateral open thoracic cordotomy for refractory cancer pain: a neglected technique?

At least 10% of patients with cancer have pain that is refractory to systemic analgesics. For most of these patients, interventional techniques may be of benefit but are often not considered or are difficult to access. Of these techniques, spinal analgesia is most commonly used in Australia and the United Kingdom, and neurosurgical procedures, such as open cordotomy with sectioning of the spinothalamic tract, are rarely used. We describe a case illustrating the successful use of bilateral open thoracic cordotomy in a patient with refractory mixed nociceptive and neuropathic pain secondary to a lumbosacral tumor. We discuss the various interventional options and review the recent literature regarding the use of both percutaneous and open cordotomy for cancer pain.

Effect of cervical dorsolateral funiculotomy on reach-to-grasp function in the rat

Cervical spinal cord injury (SCI) can severely impair reaching and grasping ability, and several descending systems, including the rubrospinal tract and corticospinal tract, have been implicated in the control of reach-to-grasp movements. The primary aim of this study was to characterize further the forelimb deficits associated with a cervical dorsolateral funiculotomy, which ablates the rubrospinal tract but spares the dorsal and ventral corticospinal tract in the rat. Adult female rats that preferred to use their right forelimb to reach for single pellets received a lesion to the right cervical dorsolateral funiculus between the C3-4 dorsal roots. Gross forelimb motor function was assessed by measuring spontaneous forelimb usage during exploration in a cylinder, and fine motor function was assessed using staircase and single pellet reaching tests. Single pellet reaching was further evaluated by qualitative and quantitative kinematic scoring of the movement components. Histological analysis included the quantification of spared white matter. Cervical dorsolateral funiculotomy produced marked deficits in reaching performance on both the single pellet and staircase reaching tests, with transient deficits in gross forelimb usage in the cylinder. Quantitative kinematics also revealed a reduction in digit abduction during the reach, which persisted throughout the 8-week post-SCI period. Tests of reach-to-grasp function, therefore, were more sensitive than a test of gross forelimb usage after cervical dorsolateral funiculotomy and did not show recovery over the 8-week survival period. We suggest that the staircase test is a useful screening tool for intervention studies because of its ease of implementation, and that the single pellet test is valuable for examining reaching accuracy and detailed kinematics.

[Effects of transection of cervical spinal cord on lipopolysaccharide induced acute lung injury in rat]

OBJECTIVE

To investigate the effects of transection of cervical spinal cord (TCSC) on acute lung injury (ALI) and its potential mechanism in rat.

METHODS

Seventy-two rats were randomly divided into three groups: normal control group (NC, n=8), endotoxemia group (ET, n=32) and endotoxemia with TCSC group (TCSC, n=32), and the latter two groups were divided into four subgroups respectively according to different time intervals (n=8). Endotoxemia model was established by injecting lipopolysaccharide (LPS, 10 mg/kg) intravenously, and the spinal cord at 7th cervical spine of rats was transected in TCSC group. Samples of blood and lung were collected at different time intervals. The plasma levels of norepinephrine (NE) and interleukin-6 (IL-6) were measured by high performance liquid chromatography (HPLC) and enzyme-lined immunosorbent assay (ELISA) respectively, and arterial blood oxygen pressure (PaO2) was determined by blood-gas analyser. The changes in histopathology and lung wet/dry weight (W/D) ratio were also observed in every group.

RESULTS

The changes in the levels of NE and lung W/D ratio of the TCSC group was significantly decreased than those of ET group, but PaO2 of TCSC group was increased obviously than that of ET group (all P<0.05), and the degree of lung injury was less intensive in the TCSC group. At all the time points, the level of IL-6 of TCSC group was lower compared with ET group (all P<0.05). The results of correlation analysis suggested that there was a positive correlation between plasma NE and IL-6 concentration (r=0.458, P<0.05), a negative correlation between NE and PaO2 (r= -0.528, P<0.05).

CONCLUSION

Sympathectomy as a result of TCSC at 7th cervical spine may palliate the degree of ALI and improve oxygenation in rats with endotoxemia by inhibiting excessive activation of adrenoceptor.

Therapeutic strategy for acute spinal cord contusion injury: cell elimination combined with microsurgical intervention

Background

No cure is available for human spinal cord injury. Cell elimination by localized radiation therapy that is timed within 2–3 weeks postinjury can facilitate repair of structure and function in transected rat spinal cord. In pilot studies in contusion spinal cord injury, a model similar to crush/fracture injury in human, we did not observe the expected beneficial effects of radiation therapy. Long forgotten data show that in contusion/crush injury, fluid accumulation from hemorrhage is critical. Alfred Reginald Allen observed that the most devastating sequelae in contusive injury are secondary to fluid accumulation which could be alleviated by surgical intervention, midline slits (myelotomy) at the lesion site.

Methods and Findings

Here, we tested whether release of fluid buildup by microsurgery (partial myelotomy) would affect the structural outcome of radiation therapy in the severely contused rat spinal cord. Surgical intervention alone significantly enhanced tissue and functional preservation in the contused cord, thus confirming Allen's observations. Combining partial myelotomy with radiation therapy that is specifically timed postinjury elicited substantial beneficial therapeutic outcome; it led to significant increase in tissue repair/preservation compared with the group that received surgical intervention only, as determined by histology and in vivo MRI. Altogether, the combined treatments led to a 1.8 fold increase in tissue repair/preservation as compared with the contused group.

Conclusions

The data suggest that a clinical protocol could be developed to treat acute human spinal cord injury through conventional clinical procedures, a combination of microsurgical manipulation and radiation therapy. These also suggest it is imperative to first prevent the secondary damage caused by fluid accumulation for a cure to be possible.

Inhibitory postsynaptic potentials in lumbar motoneurons remain depolarizing after neonatal spinal cord transection in the rat

GABA and glycine are excitatory in the immature spinal cord and become inhibitory during development. The shift from depolarizing to hyperpolarizing inhibitory postsynaptic potentials (IPSPs) occurs during the perinatal period in the rat, a time window during which the projections from the brain stem reach the lumbar enlargement. In this study, we investigated the effects of suppressing influences of the brain on lumbar motoneurons during this critical period for the negative shift of the reversal potential of IPSPs (E(IPSP)). The spinal cord was transected at the thoracic level on the day of birth [postnatal day 0 (P0)]. E(IPSP), at P4-P7, was significantly more depolarized in cord-transected than in cord-intact animals (E(IPSP) above and below resting potential, respectively). E(IPSP) at P4-P7 in cord-transected animals was close to E(IPSP) at P0-P2. K-Cl cotransporter KCC2 immunohistochemistry revealed a developmental increase of staining in the area of lumbar motoneurons between P0 and P7 in cord-intact animals; this increase was not observed after spinal cord transection. The motoneurons recorded from cord-transected animals were less sensitive to the experimental manipulations aimed at testing the functionality of the KCC2 system, which is sensitive to [K(+)](o) and blocked by bumetanide. Although bumetanide significantly depolarized E(IPSP), the shift was less pronounced than in cord-intact animals. In addition, a reduction of [K(+)](o) affected E(IPSP) significantly only in cord-intact animals. Therefore influences from the brain stem may play an essential role in the maturation of inhibitory synaptic transmission, possibly by upregulating KCC2 and its functionality.

Diaphragm recovery by laryngeal innervation after bilateral phrenicotomy or complete C2 spinal section in rats

This study aimed to highlight the functional aspects of diaphragm reinnervation by laryngeal motoneurons after bilateral phrenicotomy or complete cervical transection. The left recurrent laryngeal nerve was connected to the left phrenic nerve in 14 rats. Five months later, all bridged rats presented a substantial ipsilateral diaphragm recovery (74.2 +/- 10% of contralateral activity) whereas the diaphragm remained paralysed in non-bridged rats (n = 5/5). After additional right phrenicotomy, functional breathing persisted in bridged rats whereas all non-bridged died. After complete C2 spinal transection, diaphragm respiratory discharges persisted in bridged rats. The reinnnervation by laryngeal motoneurons was confirmed by retrograde labeling, stimulus-elicited diaphragm response by vagal stimulation and diaphragm inactivation after vagotomy. In conclusion, the recurrent-phrenic nerve anastomosis induces a reliable functional diaphragm outcome even after contralateral diaphragm denervation or complete high cervical spinal cord injury, and could be considered as a clinical repair strategy for re-establishing diaphragm autonomy following spinal cord trauma.

Genetic manipulation of intraspinal plasticity after spinal cord injury alters the severity of autonomic dysreflexia

Severe spinal cord injuries above mid-thoracic levels can lead to a potentially life-threatening hypertensive condition termed autonomic dysreflexia, which is often triggered by painful distension of pelvic viscera (bladder or bowel) and consequent sensory fiber activation, including nociceptive C-fibers. Interruption of tonically active medullo-spinal pathways after injury causes disinhibition of thoracolumbar sympathetic preganglionic neurons, and intraspinal sprouting of nerve growth factor (NGF)-responsive primary afferent fibers is thought to contribute to their hyperactivity. We investigated spinal levels that are critical for eliciting autonomic dysreflexia using a model of noxious colorectal distension (CRD) after complete spinal transection at the fourth thoracic segment in rats. Post-traumatic sprouting of calcitonin gene-related peptide (CGRP)-immunoreactive primary afferent fibers was selectively altered at specific spinal levels caudal to the injury with bilateral microinjections of adenovirus encoding the growth-promoting NGF or growth-inhibitory semaphorin 3A (Sema3a) compared with control green fluorescent protein (GFP). Two weeks later, cardio-physiological responses to CRD were assessed among treatment groups before histological analysis of afferent fiber density at the injection sites. Dysreflexic hypertension was significantly higher with NGF overexpression in lumbosacral segments compared with GFP, whereas similar overexpression of Sema3a significantly reduced noxious CRD-evoked hypertension. Quantitative analysis of CGRP immunostaining in the spinal dorsal horns showed a significant correlation between the extent of fiber sprouting into the spinal segments injected and the severity of autonomic dysreflexia. These results demonstrate that site-directed genetic manipulation of axon guidance molecules after complete spinal cord injury can alter endogenous circuitry to modulate plasticity-induced autonomic pathophysiology.

Neuronal overexpression of tissue-type plasminogen activator does not enhance sensory axon regeneration or locomotor recovery following dorsal hemisection of adult mouse thoracic spinal cord

CNS axons rarely regenerate spontaneously back to original targets following spinal cord injury (SCI). Neuronal expression of the serine protease tissue-type plasminogen activator (tPA) enhances axon growth in vitro and following PNS injury. Here we test the hypothesis that neuronal overexpression of tPA in adult transgenic mice promotes CNS axon regeneration and functional recovery following SCI. Adult wild-type and transgenic mouse spinal cords were subjected to dorsal hemisection at the level of the T10/T11 vertebrae. PCR confirmed incorporation of the transgene. Immunolabeling revealed overexpression of tPA in transgenic mice in neurons, including large-diameter neurons in lumbar dorsal root ganglia that contribute axons to the dorsal columns. Immunolabeling also revealed the presence of tPA protein within axons juxtaposing the injury site in transgenics but not wild types. In situ zymography revealed abundant enzymatic activity of tPA in gray matter of thoracic spinal cords of transgenics but not wild types. Rotorod locomotor testing revealed no differences between groups in locomotor function up to 21 days postinjury. Transganglionic tracer was injected into the crushed right sciatic nerve 28 days postinjury, and mice were killed 3 days later. There was no evidence for regrowth of ascending dorsal column sensory axons through or beyond the injury site. In conclusion, despite neuronal overexpression of tPA in injured neurons of transgenics, neither locomotor recovery nor regeneration of ascending sensory axons was observed following thoracic dorsal hemisection.

Effect of the potassium channel opener WAY-133537 on the overactive bladder of spinalized rats

AIMS

To test the efficacy of WAY-133537 for the treatment of overactive bladder (OAB) in a chronic paraplegic rat model.

MATERIALS AND METHODS

Forty-eight female Sprague-Dawley rats were used in this study. Six animals served as normal controls (without spinal cord transaction (ST)), while 42 rats underwent ST at the 10th thoracic vertebra. Two weeks after ST, cystometrogram (CMG) was performed in six randomly chosen animals to ensure the development of neurogenic detrusor overactivity. The remaining 36 rats were divided into three equal groups, 12 received the vehicle as "paraplegic controls," 12 received WAY-133537 0.3 mg/kg, and 12 received WAY-133537 3 mg/kg. Each "paraplegic control" and treatment group was further divided into two sub-groups (n = 6), with CMG at 3 and 4 weeks after ST, respectively.

RESULTS

Two weeks after ST, all "vehicle control" rats developed detrusor overactivity with a mean frequency of 0.96 and 1.48 contractions/min and amplitude of 22.96 and 31.22 cm H(2)O with 1- and 2-week treatment, respectively. Neurogenic detrusor overactivity disappeared from 50% of rats that received WAY-133537 0.3 mg/kg for 1 week, and frequency decreased to 0.41 contractions/min. After 2 weeks of treatment, detrusor overactivity vanished from 67% of the animals with even further reduction in the frequency of detrusor overactivity (0.22 contractions/min, P < 0.01). In rats that received 3 mg/kg of the drug for 1 week, detrusor overactivity disappeared from only one animal with a non-significant decline in frequency. Fifty percent of rats given WAY-133537 at the dose of 3 mg/kg/day for 2 weeks manifested no detrusor overactivity.

CONCLUSIONS

WAY-133537 shows efficacy in increasing bladder capacity and reducing the frequency of spontaneous bladder contractions after ST in rats without decreasing voiding pressure.

Differential activation of astrocytes and microglia after spinal cord injury in the fetal rat

BACKGROUND

As the immature spinal cord was nerve growth permissive, we examined glial reactions that influence regeneration of the spinal cord in a fetal rat spinal cord injury model.

METHODS

Three, 7, 21, and 35 days after intrauterine surgery, offspring were killed and the thoracic and lumbar spinal cords were carefully removed from the spinal column and then cut into 10 mum longitudinal sections. These sections were stained with hematoxylin-eosin, anti-glial fibrillary acidic protein antibody (GFAP) as a marker of astrocytes, and anti-complement CR3 antibody (OX-42) as a marker of microglia. A cordotomy model in a young adult rat was utilized as a control.

RESULTS

In the present study, collagen fibers and scar formation were seen in the severed spinal cords of mature rats, but scar formation was not seen in the fetal rat cordotomy group, regardless of spinal continuity. In the control group, biological activity of GFAP-positive cells increased over time. In the fetal rat cordotomy model, activity elevated slightly immediately after cordotomy, and disappeared shortly thereafter. In the control group, OX-42-positive macrophage-like cells proliferated over time. However, in the fetal rat cordotomy model, OX-42- positive macrophage-like cells were recognized on postoperative days 3 and 7, and then disappeared. At 5 mm from the cordotomy site, reactive microglia were recognized in the white matter of control group spinal cords, but these microglia were not recognized in the fetal rat cordotomy model.

CONCLUSIONS

In the present study, collagen fibers and scar formation were seen in the severed spinal cords of adult rats, but scar formation was not seen in the fetal rat cordotomy group. Lack of inflammation and scar formation thus appear advantageous for regeneration of the fetal spinal cord. Between fetal and mature rats, chronological changes in the immunohistochemical reactions of astrocytes and microglia following cordotomy were compared, and the results confirmed many differences. The results of the present study suggest that the presence of activated glial cells around damaged central nervous tissue and the quick disappearance of these cells after injury are important for the repair of damaged central nervous system tissue, and that the role of glial cells in nerve regeneration can change depending on the level of maturity of glial cells or surrounding cells, site of injury, or the state of tissue around the injury.

Combining Schwann cell bridges and olfactory-ensheathing glia grafts with chondroitinase promotes locomotor recovery after complete transection of the spinal cord

Numerous obstacles to successful regeneration of injured axons in the adult mammalian spinal cord exist. Consequently, a treatment strategy inducing axonal regeneration and significant functional recovery after spinal cord injury has to overcome these obstacles. The current study attempted to address multiple impediments to regeneration by using a combinatory strategy after complete spinal cord transection in adult rats: (1) to reduce inhibitory cues in the glial scar (chondroitinase ABC), (2) to provide a growth-supportive substrate for axonal regeneration [Schwann cells (SCs)], and (3) to enable regenerated axons to exit the bridge to re-enter the spinal cord (olfactory ensheathing glia). The combination of SC bridge, olfactory ensheathing glia, and chondroitinase ABC provided significant benefit compared with grafts only or the untreated group. Significant improvements were observed in the Basso, Beattie, and Bresnahan score and in forelimb/hindlimb coupling. This recovery was accompanied by increased numbers of both myelinated axons in the SC bridge and serotonergic fibers that grew through the bridge and into the caudal spinal cord. Although prominent descending tracts such as the corticospinal and reticulospinal tracts did not successfully regenerate through the bridge, it appeared that other populations of regenerated fibers were the driving force for the observed recovery; there was a significant correlation between numbers of myelinated fibers in the bridge and improved coupling of forelimb and hindlimb as well as open-field locomotion. Our study tests how proven experimental treatments interact in a well-established animal model, thus providing needed direction for the development of future combinatory treatment regimens.

[Cordotomy in the treatment of pain conditions]

During the time interval from January 1978 to January 2003, total of 128 chordotomy procedures have been done due to cancer's pain at the Institute of neurosurgery in Clinical Centre of Serbia. That pain has been mostly of uncontrolled intensity and it was resistant on applieed conservative treatment. Bilateral chordotomy has been performed in 6 patients only in exceptional cases when fixed paraplegia has proved; unilateral chordotomy has been performed in 122 cases. Bilateral chordotomy is much more dangerous than unilateral one because of greater posibility of appearance of motor deficits, sphincteral disturbances or subsequent formed pain. This procedure has several negative aspects. Firstly, it is an opened surgical intervention in general anesthesia and therefore, there is no communication with patient. We had a habit to perform DREZ surgery rather than chordotomy when ever it has been indicated. In 80.1% of all cases, the successfulness of surgery has been marked as excellent, in 15.2% of all cases, it has been marked as good, and in 4.7% of all cases, bad outcome has been detected. The rate of complication was 4.4%.

L1.1 is involved in spinal cord regeneration in adult zebrafish

Adult zebrafish, in contrast to mammals, regrow axons descending from the brainstem after spinal cord transection. L1.1, a homolog of the mammalian recognition molecule L1, is upregulated by brainstem neurons during axon regrowth. However, its functional relevance for regeneration is unclear. Here, we show with a novel morpholino-based approach that reducing L1.1 protein expression leads to impaired locomotor recovery as well as reduced regrowth and synapse formation of axons of supraspinal origin after spinal cord transection. This indicates that L1.1 contributes to successful regrowth of axons from the brainstem and locomotor recovery after spinal cord transection in adult zebrafish.

Continuous Intrathecal Meperidine for Severe Refractory Cancer Pain

The control of severe cancer pain may be problematic despite advances in pain management. Patients with severe intractable pain and/or intractable side effects may require aggressive interventional pain management strategies including the administration of medications by the continuous intrathecal route and/or neurosurgical procedures. Various medications, including opioids, local anesthetics, and alpha-2 agonists may be used intrathecally for the control of cancer pain. Failure of the intrathecal route may require the additional use of neurosurgical procedures such as cordotomy for pain control. We describe a case of severe cancer pain refractory to conventional intrathecal medications and cordotomy that was successfully managed by the addition of meperidine to the intrathecal regimen.

[Spinal cord regeneration in rats after thoracic segmentectomy: restoration of the anatomical integrity of the spinal cord]

Spinal cord (SC) segmentectomy was performed at ThX level in 28 rats. The scar formation in place of surgery and the degree of restoration of anatomical integrity were studied in control rats (group I) and in rats, in which SC defect was replaced by either Spherogel neuromatrix (group II) or Spherogel containing dispersed embryonic nerve cells (group II). While in group I rats by weeks 1-2 SC defect was filled with fibrin masses, in rats of experimental groups II and III the formation of connective tissue scar was found by the same time. By weeks 10-11 these animals demonstrated partial restoration of motion in three joints of the hindlimb. In the scar tissue and in adjacent SC zones numerous regenerating thin myelinated nerve fibers were found. They were clearly demonstrated in the zones of cranial and caudal borders along the whole distance until the appearance of typical tissue of SC. In slides from the animals of control group, thin myelinated nerve fibers were found only in close proximity to SC substance, while in the scar tissue and in the cellular bands of the intermediate zone nerve fibers were scarce.

Comparison of the effects on spinal reflexes of acetylsalicylate and metamizol in spinalized and normal rats

The effects of nonsteroidal antiinflammatory drugs, acetylsalicylate and metamizol, on spinal monosynaptic reflexes were investigated in spinalized and normal rats. Adult rats (n=36) weighing 150-200 g were anesthetized with ketamine and artificially ventilated. Half of rats were spinalized at C1 level. A laminectomy was performed in the lumbosacral region. Following electrical stimulation of the sciatic nerve by single pulses, reflex potentials were recorded from the ipsilateral L5 ventral root. Acetylsalicylate was administered orally (100 mg/kg for both spinalized and normal rats). Metamizol was administered intramuscularly (15 mg/kg for both spinalized and normal rats). These drug administrations significantly decreased the amplitude of reflex response in all groups (p < 0.05). These data verify that observed inhibition by acetylsalicylicate and metamizol may be at the level of spinal cord. Also we suggested that the cyclooxygenase products of arachidonic acid may play an important role in regulating the reflex potential.

Ablative procedures for chronic pain

The advent of neuroaugmentative techniques has reduced the application of neuroablative procedures, especially as regards pain of functional origin. Although intracranial ablative procedures are now rarely performed, spinal ablative procedures, such as anterolateral cordotomies or midline myelotomies, remain important in the management of cancer pain. These procedures produce immediate and satisfactory pain relief with acceptable complication rates. An important future trend will be the application of radiosurgery guided by functional imaging (eg,fMRI, PET) to place such intracranial lesions as cingulotomies or medial thalamotomies.

The surgical treatment of chronic pain: destructive therapies in the spinal cord

Stereotactic pain surgery is accepted as a group of procedures. These are usually highly sophisticated and technically risky procedures. In practice, the most important part of this discipline is not the technical abilities of the surgeon, but selection of the most appropriate patients for the available procedures. We must remember that we are performing all these procedures with the cooperation of patients. The energy that is used for lesioning can be stopped when desired. The target we want to approach can be definitely and anatomically visualized and demonstrated, and the function of the target is evaluated with neurophysiologic impedance techniques and stimulation. Thus, if we are able to understand the language of the central nervous system, these are available, effective, and safe procedures in neurosurgical practice. We must remember that if intractable pain can be controlled by minimally invasive destructive techniques, the patients will not be dependent on implantable systems, drugs,and medical units. This independent lifestyle is a critical goal central to quality of life for patients having intractable pain.

Multiple Spontaneous Rhythmic Activity Patterns Generated by the Embryonic Mouse Spinal Cord Occur Within a Specific Developmental Time Window

Spontaneous rhythmic activity is a ubiquitous phenomenon in developing neural networks and is assumed to play an important role in the elaboration of mature circuitry. Here we describe the day-by-day evolution of spontaneous activity in the embryonic mouse spinal cord and show that, at a specific developmental stage, 2 distinct rhythms coexist. On embryonic days E12.5 and E13.5, we observed a single type of regularly recurring short spike-episodes synchronized across cervical, thoracic, and lumbar levels. By E14.5, in addition to this motor rhythm, another type of spontaneous synchronous activity appeared, characterized by much longer lasting episodes separated by longer time intervals. On E15.5, these long episodes disappeared. Short episodes were less numerous and more irregular except at the cervical level where a rhythm was occasionally observed. By E16.5, this cervical rhythm became more robust, whereas the lumbar level fell almost silent. Surprisingly, at E17.5, spontaneous activity resumed at caudal levels, now characterized by numerous erratic short episodes. A striking ontogenetic feature of spontaneous activity was the occurrence of long episodes only at E14.5. Although concomitant at all levels of the spinal cord, long episodes displayed different patterns along the spinal cord, with tonic firing at the thoracic level and rhythmic discharge with occasional sequences of left/right alternation at the lumbar level. Thus at E14.5, the originally synchronized network has started to segregate into more specialized subnetworks. In conclusion, this work suggests that ongoing spontaneous rhythms do not follow a smooth evolution during maturation, but rather undergo profound changes at very specific stages.

Effect of spinal cord injury on urinary bladder spinal neural pathway: a retrograde transneuronal tracing study with pseudorabies virus

OBJECTIVES

To determinate the effect of acute and chronic spinal cord injury (SCI) resulting from thoracic cord transection on the urinary bladder spinal neural pathway.

METHODS

Seventy-six adult Sprague-Dawley rats were randomly divided into four groups, non-SCI (normal rats undergoing no surgical procedure except pseudorabies virus [PRV] injection), SCI(b) (SCI and PRV injected immediately after SCI), SCI(c) (SCI and PRV injected at 3 weeks after SCI), and SCI(d) (SCI and PRV injected at 3 months after SCI). Transcardiac perfusion fixation was done at appropriate survival periods after PRV injection into the bladder wall tissue. Sections of the dorsal root ganglion, spinal cord, and brain were processed for visualization of the virus by the streptavidin-peroxidase immunohistochemical procedure.

RESULTS

The bladder weight of the non-SCI, SCI(b), SCI(c), SCI(d) rats was 144 +/- 9 mg, 142 +/- 8 mg, 486 +/- 51 mg, and 656 +/- 69 mg, respectively. The time-ordered flow charts of PRV tracing were similar in the non-SCI and SCI rats. The cross-sectional area of the labeled dorsal root ganglion cell profiles increased significantly after SCI (P <0.001): 593 +/- 40 microm2, 588 +/- 39 microm2, 815 +/- 53 microm2, and 902 +/- 57 microm2 in the non-SCI, SCI(b), SCI(c), SCI(d) rats, respectively. The number of labeled cells in the dorsal horn in the L6 and S1 segments 3 days after PRV injection markedly increased in chronic SCI rats, as did the number of labeled motor neurons 4 days after injection.

CONCLUSIONS

Acute and chronic SCI have no effect on the process of virus transneuronal transport below the level of the lesion. Subsequent to chronic SCI, reorganization of the micturition reflex pathways may occur.

The role of the dorsal columns in neuropathic behavior: evidence for plasticity and non-specificity

Despite conflicting clinical and experimental evidence, textbook description of somatic sensations continues to follow a rigid dichotomy based on the concept that pain sensation is transmitted cephalad primarily through anterolateral pathways, while touch is mediated through the dorsal column pathway. This study provides an example of the dynamic rerouting in the transmission of the nociceptive signals following injuries to the peripheral and central processes of sensory neurons. In two rat models for mononeuropathy, the chronic constriction injury model [Bennett, G.J., Xie, Y.K., Pain 33 (1988) 87-107] and the spared nerve injury model [Decosterd, I., Woolf, C.J., Pain 87 (2000) 149-158], we demonstrate that selective dorsal columns lesion produced significant decrease of tactile and cold allodynias and thermal hyperalgesia which were assessed by the Von Frey hair filaments, the acetone drop test and the heat-induced paw withdrawal, respectively. These manifestations, however, can reappear 2 weeks after bilateral dorsal column lesion in rats subjected to spared nerve injury mononeuropathy and appear also in animals sustaining chronic bilateral dorsal column lesion followed by either model of mononeuropathy. Lesion of the dorsal column on the side opposite to the neuropathic leg did not alter the neuropathic manifestations in both animal models. Changes in the sequence of timing of the dorsal column lesion and induction of mononeuropathy, suggest that the effects of the former last for 1 to 2 weeks. The results of this study show that the dorsal columns are involved in neuropathic manifestations and at the same time are not necessary for their full development and persistence. Furthermore, these results shade doubts on the validity of the concept of segregation of pathways involved in the transmission of neuropathic manifestations. Therefore, principles governing acute pain transmission are not necessarily applicable to chronic pain situations. The latter conditions seem to engage other available pathways to reestablish the pain signaling system.

Functional plasticity in the human primary somatosensory cortex following acute lesion of the anterior lateral spinal cord: neurophysiological evidence of short-term cross-modal plasticity

The primary somatosensory cortex (S1) in adult animals and humans is capable of rapid modification after deafferentation. These plastic changes may account for a loss of tonic control by nociceptive inputs over inhibitory mechanisms within structures of the dorsal column-medial lemniscal system. Most studies, however, have been performed under conditions where deafferentation of C and A delta fibres coexists with large-diameter fibres deafferentation. In this study the effect of the acute lesion of one ascending anterior lateral column on neuronal activity within the dorsal column-medial lemniscal system was assessed by recording somatosensory evoked potentials (SEPs) in seven patients who underwent unilateral percutaneous cervical cordotomy (PCC) as treatment for drug-resistant malignant pain.Spinal, brainstem and cortical SEPs were recorded 2h before and 3h after PCC by stimulating the posterior tibial nerve at both ankles. Amplitudes of cortical potentials obtained by stimulation of the leg contralateral to PCC were significantly increased after PCC. No significant changes in spinal or brainstem potentials were observed. PCC did not affect SEP components obtained by stimulation of the leg ipsilateral to PCC. Our results suggest that nociceptive deafferentation may induce a rapid modulation of cortical neuronal activity along the lemniscal pathway, thus providing the first evidence in humans of short-term cortical plasticity across the spinothalamic and lemniscal systems.

Axonally transported peripheral signals regulate alpha-internexin expression in regenerating motoneurons

The class IV neuronal intermediate filament (IF) family proteins includes the neurofilament (NF) triplet proteins NF-L, NF-M, and NF-H and also the more recently characterized alpha-internexin-NF66. It is well established that NF-L, -M, and -H protein and mRNA are downregulated after peripheral nerve injury. We examined alpha-internexin protein expression after three facial nerve lesion paradigms: crush, transection, and resection. Alpha-internexin immunoreactivity was absent in the perikarya of uninjured facial motoneurons but increased dramatically in all three injury paradigms, with maximum immunoreactivity observed at 7 d after injury. Twenty-eight days after nerve crush or transection, there was a dramatic decrease in the number of alpha-internexin-positive cells. In contrast, alpha-internexin remained elevated 28 d after nerve resection, an injury that hinders regeneration and target reinnervation. In situ hybridization studies showed an increase in alpha-internexin mRNA expression in the facial nucleus at 7 and 14 d after injury. Retrograde transport of fluorogold from the whisker pads to the facial nucleus was seen only in motoneurons that lacked alpha-internexin immunoreactivity, supporting the idea that target reinnervation and inhibitory signals from the periphery regulate the expression of alpha-internexin. Blockage of axonal transport through local colchicine application induced strong immunoreactivity in motoneurons. Alpha-internexin expression was also examined after central axotomy of rubrospinal neurons, which constitutively show alpha-internexin immunoreactivity. After rubrospinal tractotomy, alpha-internexin immunoreactivity transiently increased by 7 d after injury but returned to control levels by 14 d. We conclude that alpha-internexin upregulation in injured motoneurons suggests a role for this IF protein in neuronal regeneration.

Association of spinothalamic lamina I neurons and their ascending axons with calbindin-immunoreactivity in monkey and human

The calbindin-immunoreactivity of spinothalamic (STT) lamina I neurons and their ascending axons was examined in two experiments. In the first experiment, lamina I STT neurons in macaque monkeys were double-labeled for calbindin and for retrogradely transported WGA*HRP following large (n=2) or small (n=1) injections that included the posterior thalamus. Most, but not all (78%) of the contralateral retrogradely labeled lamina I STT cells were positive for calbindin. Calbindin-immunoreactivity was not selectively associated with any particular anatomical type of lamina I STT cell; 82% of the fusiform cells, 78% of the pyramidal cells and 67% of the multipolar cells were double-labeled. In the second experiment, oblique transverse sections from upper cervical spinal segments of three macaque monkeys, one squirrel monkey and five humans were stained for calbindin-immunoreactivity. In each case, a distinct bundle of fibers was densely stained in the middle of the lateral funiculus. This matches the location of anterogradely labeled ascending lamina I axons observed in prior work in cats and monkeys, and it matches the location of the classically described 'lateral spinothalamic tract' in humans. This bundle had variable shape across cases, an observation that might have clinical significance. These findings support the view that lamina I STT neurons are involved in spinal cordotomies that reduce pain, temperature and itch sensations.

The roles of pathways in the spinal cord lateral and dorsal funiculi in signaling nociceptive somatic and visceral stimuli in rats

The spinothalamic tract (STT) is a major ascending nociceptive pathway, interruption of which by cordotomy is used for pain relief, whereas the dorsal column (DC) pathway is usually not considered to be involved in pain transmission. However, recent clinical studies showed good relief of visceral pain in cancer patients after a DC lesion. Electrophysiological recordings in animals suggest that the analgesic effect is due to interruption of axons ascending from postsynaptic dorsal column (PSDC) neurons located in the vicinity of the central canal. In this behavioral study, we used a decrease in exploratory activity in rats after a noxious stimulus as an indicator of perceived pain, independent of withdrawal reflexes. Intradermal capsaicin injection almost abolished exploratory activity in naïve animals or in rats after a DC lesion, but did not change it in rats after ipsilateral dorsal rhizotomy or a lesion of the lateral funiculus on the side opposite to the injection. In contrast, a bilateral DC lesion counteracted the decrease in exploratory activity induced by noxious visceral stimuli for at least 180 days after the surgery. Although neurons projecting in both the STT and the PSDC path can be activated by noxious stimuli of cutaneous or visceral origin, our results suggest that the STT plays a crucial role in the perception of acute cutaneous pain and that the DC pathway is important for transmission of visceral pain.

Norepinephrine metabolism in neuron: dissociation between 3,4-dihydroxyphenylglycol and 3,4-dihydroxymandelic acid pathways

AIM

To investigate the pre-synaptic metabolism of norepinephrine (NE), judged by variations in plasma concentration of 3,4-dihydroxyphenylglycol (DHPG) and 3,4-dihydroxymandelic acid (DOMA).

METHODS

Pithed and electrically stimulated (2.5 Hz) rats were given intravenous infusion of exogenous NE (6 nmol . kg-1 . min-1). Plasma NE, DHPG, DOMA, and the activities of mono- amine oxidases (MAO) were measured with the radio-enzymatic assay.

RESULTS

Exogenous NE induces an about 100-fold increase in plasma NE concentration while blood pressure remained within normal limits. A 12-fold increase in plasma DHPG and 1.2-fold increase for DOMA were observed. When NE transportation across the pre-synaptic membrane was inhibited by desipramine (2 mg/kg, iv), a great reduction in plasma DHPG concentration (about 25 % of control) was observed while DOMA remained unchanged. When MAO-A activity was inhibited to 25 % of control by clorgyline (2 mg/kg, iv) and MAO-B to 30 % by deprenyl, the plasma DHPG and DOMA concentrations were reduced to 15 % and 70 % of controls, and to 26 % and 76 % of controls, respectively. When clorgyline and deprenyl were combined, plasma DHPG was vanished (less than 2 % of control) while plasma DOMA remained in the same range (72 % of control).

CONCLUSION

The metabolizing system of NE in pre-synapse, associating with the pre-synaptic reuptake plus oxidative deamination on the external membrane of mitochondria, is predominant for the reduction to DHPG.

Neurosurgical approaches to pain treatment

In a multidisciplinary approach to the management of chronic pain, neurosurgical methods are an indispensable part of the therapeutic armamentarium. With the exception of percutaneous interventions for trigeminal neuralgia and facet joint syndromes, most ablative pain surgery procedures (neurotomy, rhizotomy, sympathectomy, etc.) have been replaced by neuromodulatory approaches such as electrical stimulation of the central nervous system (CNS). However, cordotomy is still a valuable operation for certain forms of cancer related pains (Pancoast's syndrome, breakthrough pain) which are relatively resistant to pharmacotherapy. Another example of ablative surgery is the dorsal root entry zone (DREZ) operation, which is generally the only treatment option for pain due to root avulsion and segmental pain in spinal cord injury. Spinal cord stimulation (SCS) has proven to be most useful for the management of pain following peripheral nerve injury (including complex regional pain syndromes) and rhizopathy. For these conditions which are otherwise often therapy resistant, SCS may produce substantial and long-lasting pain relief in 60-70% of the patients. Considering that such pains are common and the fact that SCS has been shown to be cost-effective, this treatment is no doubt at present underused. Complications and side-effects are very rare. SCS has also been found to be useful for pain in peripheral vascular disorders and angina pectoris. In the latter condition the overall results are favorable in about 80% of patients with a significant reduction of the frequency and severity of angina attacks and the need for nitrates. Stimulation of the motor cortex is a novel and promising treatment of central, post-stroke pain and painful trigeminal neuropathy.

Adaptations in myosin heavy chain profile in chronically unloaded muscles

In this review, myosin heavy chain (MHC) adaptations in response to several models of decreased neuromuscular activity (i.e. electrical activation and loading of a muscle) are evaluated. In each of these "reduced-activity" models it is important to: a) quantify the changes in electrical activation of the muscle as a result of the intervention; b) quantify the forces generated by the muscle; and c) determine whether the neuromuscular junction remains normal. Most of the models, including spaceflight, hindlimb suspension, spinal cord isolation, spinal cord transection, denervation, and limb immobilization in a shortened position, result in increases in the percentage of fast MHCs (or fast MHC mRNA) in normally slow rat muscles. It also can be inferred from histochemical data that increases in fast MHCs occur with TTX application and bed rest. The only "reduced-activity" model to consistently increase slow muscle myosin mRNA, and slow fibers is limb immobilization in a stretched position; however, this model results in at least a temporary increase in tension. It appears that the most common feature of these models that might induce MHC adaptations is the modification in loading rather than a change in the neuromuscular activity.

New pain following cordotomy: clinical features, mechanisms, and clinical importance

OBJECT

The clinical features, possible causes, and contributing factors associated with novel spontaneous pain following unilateral cordotomy were investigated to clarify the mechanism and clinical importance of this pain.

METHODS

Forty-five patients who underwent cordotomy for severe unilateral cancer pain were included in this study. New pain occurred in 33 (73.3%) of 45 patients. Pathological conditions of tissue demonstrated on imaging corresponded to new pain in eight patients, referred pain in five, and neither of these in 15 patients. New pain was centered opposite the site of the original pain in a mirror-image location in 28 patients and rostral to the original pain in five patients. It was temporary in seven patients, weaker than the original pain in 25, and as severe as the original pain in one patient. The incidence of moderate or severe pain was significantly higher in patients with confirmed tissue disease (six of eight patients) than in those without (six of 20 patients). An important contributing factor to the occurrence of new pain was the achievement of analgesia by performing the cordotomy.

CONCLUSIONS

The present results indicate that new pain occurs frequently after unilateral cordotomy. Nonetheless, cordotomy may still be indicated for unilateral uncontrollable pain because new pain, when present, was weaker and more easily controlled than the original pain in nearly all cases. The authors speculate that new pain may represent a type of referred pain from the original painful area or may arise from sensitization of contralateral spinal nociceptive circuits due to metastasis or tumor infiltration, and that new pain is potentiated by the interruption of descending inhibitory pathways.

Inhibition of pudendal reflexes in spinal rats. Reassessing the role of serotonin

The effects of serotonin (5-HT) and thyrotropin-releasing hormone (TRH) on penile reflexes were investigated in intact and spinally transected male rats. Doses of intrathecal 5-HT (0.0, 1.13, 2.26, 11.3, 22.6, and 113.0 nmol), in a range previously shown to inhibit pudendal reflexes in anesthetized spinal preparations, prolonged the latency to the first penile erection in awake intact rats. However, these doses also provoked hyperreactivity and vocalization. Doses of intrathecal TRH (100 and 500 pmol) that effectively inhibited penile erection in intact animals were less effective in spinalized animals. Finally, a combination of subthreshold doses of TRH (100 pmol) and 5-HT (4.0 nmol) at a ratio known to affect other TRH/5-HT-mediated circuits significantly extended erection latency in animals with spinal transections. These data suggest that 5-HT and TRH are both involved in the inhibitory circuits regulating penile erection, either through corelease onto the same population of cells or through independent release onto different populations of neurons.

Posttraumatic therapeutic vaccination with modified myelin self-antigen prevents complete paralysis while avoiding autoimmune disease

Spinal cord injury results in a massive loss of neurons, and thus of function. We recently reported that passive transfer of autoimmune T cells directed against myelin-associated antigens provides acutely damaged spinal cords with effective neuroprotection. The therapeutic time window for the passive transfer of T cells was found to be at least 1 week. Here we show that posttraumatic T cell-based active vaccination is also neuroprotective. Immunization with myelin-associated antigens such as myelin basic protein (MBP) significantly promoted recovery after spinal cord contusion injury in the rat model. To reduce the risk of autoimmune disease while retaining the benefit of the immunization, we vaccinated the rats immediately after severe incomplete spinal cord injury with MBP-derived altered peptide ligands. Immunization with these peptides resulted in significant protection from neuronal loss and thus in a reduced extent of paralysis, assessed by an open-field behavioral test. Retrograde labeling of the rubrospinal tracts and magnetic resonance imaging supported the behavioral results. Further optimization of nonpathogenic myelin-derived peptides can be expected to lead the way to the development of an effective therapeutic vaccination protocol as a strategy for the prevention of total paralysis after incomplete spinal cord injury.

Cordotomy for bilateral cord abductal paralysis

OBJECTIVE

To investigate the clinical effects of cordotomy on bilateral cord abductal paralysis.

METHODS

With unilateral cordotomy, we treated 4 patients with bilateral cord paralysis whose glottis size was about 2.0 mm to 2.5 mm. They were followed up for over one year.

RESULTS

One week after surgery, the tracheotomy tubes of all 4 patients were plugged and no dyspnea occurred during rest and mild action. Their voices were more hoarse than before surgery. After 3 months, the tracheotomy tubes were successfully decannulated, and in the following one year, their respiration was normal and then speech was clear, although their voices were still a little hoarse.

CONCLUSION

We suggest that cordotomy be one option in the treatment of bilateral cord abductal paralysis.

The crossing of the spinothalamic tract

The question whether the spinothalamic and spinoreticular fibres cross the cord transversely or diagonally was investigated in cases of anterolateral cordotomy and in a case of thrombosis of the anterior spinal artery. The pattern of sensory loss following transection of the anterolateral quadrant of the cord consists of a narrow area of decreased nociception and thermanalgesia at the level of the incision; it extends for 1-2 segments cranial and cordal to the incision. This area is immediately cranial to the area of total loss of these modalities. This pattern of sensory loss is explained as follows. The cordotomy incision transects two groups of fibres: those that are already within the anterior and anterolateral funiculi and those that are crossing the cord. The area of total thermanaesthesia and analgesia is due to transection of fibres that are already within this region. The area of partial sensory loss is due to transection of the fibres that are crossing the cord at that level. Owing to the craniocaudal extent of the branches of the dorsal roots, there is an overlap of their collaterals that results in every spinothalamic neurone receiving an input from several dorsal roots. The narrow cordotomy incision thus divides the few fibres crossing at that level, causing diminished noxious and thermal sensibility over a few segments above and below the incision. These facts can be accounted for only on the assumption that these spinothalamic fibres are crossing the cord transversely. This evidence of transverse crossing was found in the cervical, thoracic and lumbar segments. There were three of 63 cordotomies for which this explanation of the partial sensory loss could not be maintained. Although no explanation has been suggested, this is unlikely to be due to the fibres crossing the cord diagonally.

Delayed glial cell death following wallerian degeneration in white matter tracts after spinal cord dorsal column cordotomy in adult rats

The devastating consequences of spinal cord injury (SCI) result primarily from damage to long tracts in the spinal white matter. To elucidate the secondary injury processes occurring after SCI, we investigated the relationship between apoptosis and Wallerian degeneration in spinal white matter tracts. In the rat spinal cord, the corticospinal tract (CST) and the dorsal ascending tract (DAT) are separated from each other in the dorsal column and relay information in opposite directions. A dorsal column cordotomy at the eighth thoracic (T8) level simultaneously induces Wallerian degeneration in the CST caudal to and in the DAT rostral to the injury. Using the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method, we demonstrate that apoptosis occurred in areas of Wallerian degeneration in both tracts throughout the length of the cord segments studied (from T3 to T12). This delayed cell death, more apparent in the DAT, began at 7 days after injury and peaked at 14 days for the DAT and 28 days for the CST. Although a few TUNEL+ cells, slightly above the noninjury control level, were found in intact areas of both tracts, statistically significant differences in the number of TUNEL+ cells were found between the intact and the lesioned tract segments (CST, F < 0.01; DAT, F < 0.001). Within a particular spinal segment, a mean number of 64 and 939 TUNEL+ cells in the degenerating CST and DAT, respectively, were estimated stereologically at 14 days postinjury. TUNEL+ cells in degenerating tracts outnumber their intact counterparts by 3.8:1 in the CST and 4.1:1 in the DAT, although a statistically significant difference between the two was only found in the DAT at this time point (P < 0.05). Finally, we demonstrated that oligodendrocytes, the myelin-forming cells in the central nervous system, constitute at least a portion of the cells undergoing apoptosis within areas of Wallerian degeneration.

Blunted pressor responsiveness to intravenous quinpirole in conscious, chronic spinal cord-transected rats: peripheral vs. spinal mechanisms

Intravenous quinpirole (1 mg/kg) in conscious rats with chronic spinal cord transection (at T5-T7) induced an initial pressor effect, which was significantly reduced in both magnitude and duration compared with that in sham-operated rats, which was then followed by a long-lasting depressor effect. To distinguish the spinal and/or peripheral origin of this phenomenon, conscious, spinal cord-transected rats were also pretreated with either intravenous (0. 5 mg/kg), intrathecal (40 microg/kg) or combined intravenous and intrathecal domperidone, a dopamine D(2) receptor antagonist that does not cross the blood-brain barrier. Intravenous pretreatment with domperidone enhanced, but did not completely restore, the pressor effect of quinpirole, and had no effect upon the depressor component. However, both the depressor component and the reduction of the pressor effect induced by spinal section were fully abolished by intrathecal or combined intrathecal and intravenous domperidone. Quinpirole-induced changes in mean aortic pressure were also fully abolished by intravenous pretreatment with metoclopramide (5 mg/kg). Neither the pressor nor the bradycardiac response to intravenous phenylephrine differed between sham-operated and spinal rats. These results suggest that the blunted pressor response to quinpirole after spinal cord transection is related to an enhanced spinal dopamine D(2) receptor-mediated depressor effect rather than to hypersensitivity of peripheral dopamine D(2) receptors or vascular hyporesponsiveness to alpha(1)-adrenoceptor stimulation. Thus, in conscious intact rats, the prominent central pressor effect of quinpirole seems to oppose, not only a peripheral sympathoinhibitory depressor effect, as previously thought, but also a spinal depressor effect.