Potential neurotoxicity of spinal anesthesia with lidocaine

Survey investigation of articaine use in the United States

BACKGROUND

Local anesthesia is an essential component of dentistry, but there is limited quantifiable understanding of what techniques and local anesthetic solutions are used by practicing dentists. Use of the local anesthetic articaine has been highly debated in dentistry regarding its efficacy and risks for paresthesia. The aims of this study were to expand the knowledge of local anesthesia practices of dentists in the United States through a large-scale survey and associate potential influencing factors regarding articaine use specifically.

METHODS

The 23-item survey was sent to 10,340 practicing dentists in the United States, gathering demographic data and local anesthesia approaches and concerns. Statistical analysis consisted of descriptive, bivariate, and multivariate logistic regression analyses.

RESULTS

A total of 1,128 dentists completed the survey. Previous experience with articaine was reported by 97.6% of respondents, with 3.3% no longer using articaine. Sixty percent of respondents indicated using articaine for most local anesthetic injections administered. Multivariable regression analysis found those reporting to use articaine for all local anesthetic injections involving vasoconstrictors were more likely to be male (odds ratio, 1.59; P = .002) or general dentists (odds ratio, 1.63; P < .001).

CONCLUSIONS

Articaine has a perceived benefit to practitioners as most respondents reported using articaine as their primary local anesthetic. A practitioner's sex and type were found to affect the profile of use of articaine.

PRACTICAL IMPLICATIONS

Assembling evidenced-based local anesthesia practices would be beneficial to ensure US practitioners are more standardized in administering local anesthetics, particularly articaine, in the safest and most efficacious way.

P53 and taurine upregulated gene 1 promotes the repair of the DeoxyriboNucleic Acid damage induced by bupivacaine in murine primary sensory neurons

The research aimed to explore the biological role of p53 protein and long non-coding RNA (lncRNA) taurine upregulated gene 1 (TUG1) in bupivacaine (bup)-induced neurotoxicity. Our work treated dorsal root ganglion (DRG) cells with bup, detected cell viability through CCK-8, apoptosis through TUNEL assays, DeoxyriboNucleic Acid (DNA) damage through γ-H2AX protein and comet assay, including p53 mRNA, protein and TUG1 expression through q-PCR and western blot, furthermore, cell viability and DNA damage were determined after the silencing of p53 and TUG1, biological information and TUG1 FISH combined with p53 protein immunofluorescence (IF) was performed to determine the cellular localization of these molecule. In vivo experiments, we explored the impact of intrathecal injection of bup on p53 mRNA and protein, TUG1, γ-H2AX protein expression. The results showed that bup was available to signally decreased cell viability, promoted apoptosis rate and DNA damage, additionally, bup increased p53 mRNA and protein and TUG1 expression. P53 siRNA and TUG1 siRNA significantly increased DNA damage. Furthermore, bioinformatics analysis and colocalization experiments revealed that the p53 protein is a transcription factor of TUG1, in vivo experiment, intrathecal injection of bup increased the p53 mRNA, p53 protein, TUG1 and γ-H2AX protein in the murine DRG. In this study, it was found p53 and TUG1 promote the repair of the DNA damage induced by bup in murine dorsal root ganglion cells, suggesting a new strategy for the amelioration of bup-induced neurotoxicity.

Risk of Dementia in Patients Who Underwent Surgery under Neuraxial Anesthesia: A Nationwide Cohort Study

The incidence of dementia in patients with surgery under neuraxial anesthesia and the possibility of surgery under neuraxial anesthesia as a risk factor for dementia were investigated. We performed a retrospective matched cohort study with nationwide, representative cohort sample data of the Korean National Health Insurance Service in South Korea between 1 January 2003, and 31 December 2004. The participants were divided into control (n = 4488) and neuraxial groups (n = 1122) using propensity score matching. After 9 years of follow-up, the corresponding incidences of dementia were 11.5 and 14.8 cases per 1000 person-years. The risk of dementia in the surgery under neuraxial group was 1.44-fold higher (95% confidence interval [95%CI], 1.17-1.76) than that in the control group. In the subgroup analysis of dementia, the risk of Alzheimer's disease in those who underwent surgery under neuraxial anesthesia was 1.48-fold higher (95%CI, 1.17-1.87) than that in those who did not undergo surgery under anesthesia. Our findings suggest that patients who underwent surgery under neuraxial anesthesia had a higher risk of dementia and Alzheimer's disease than those who did not undergo surgery under neuraxial anesthesia.

Downregulation of microRNA-199a-5p alleviated lidocaine-induced sensory dysfunction and spinal cord myelin lesions in a rat model

Lidocaine induces neurotoxicity in the spinal cord, but the underlying mechanisms remain unclear. In this study, we evaluated the effects of miR-199a-5p on 10 % lidocaine neurotoxicity. Increased expression of miR-199a-5p in the spinal cord of rats treated with 10 % lidocaine was assessed by qRT-PCR. Furthermore, after miR-199a-5p antagomir administration, the sensory dysfunction and myelin sheath lesions (evaluated by semithin sections stained with toluidine blue, electron microscopy, g-ratios and myelin thickness) induced by 10 % lidocaine were alleviated. Myelin regulatory factor (MYRF), a key molecule of myelin sheath development, was predicted to be a target gene of miR-199a-5p by the TargetScan and miRBase databases. MYRF and its downstream factors myelin basic protein (MBP), proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG) were significantly decreased after intrathecal 10 % lidocaine administration. Moreover, these changes were reversed after miR-199a-5p antagomir administration. FISH-immunofluorescence showed coexpression of miR-199a-5p and MYRF in the spinal cord white matter of rats. A luciferase reporter assay further demonstrated the functional association between miR-199a-5p and MYRF. Overall, miR-199a-5p upregulation is involved in 10 % lidocaine-induced spinal cord toxicity through regulation of MYRF. Therefore, downregulating miR-199a-5p expression may be a potential strategy to ameliorate spinal cord neurotoxicity induced by 10 % lidocaine.

An inadvertent subarachnoid injection reversed by cerebrospinal fluid lavage for the treatment of chronic low back pain: A case report

RATIONALE

We present a case of high spinal anesthesia after inadvertent injection of local anesthetics and corticosteroids into the subarachnoid space during attempted epidural injection. Cerebrospinal fluid (CSF) lavage is a suitable method for treatment.

PATIENT CONCERNS

A 45-year-old woman presented with posterior thigh, leg, and ankle pain for >6 months and was treated with epidural injection. Five minutes after the third time of epidural injection, the patient complained loss of sensation and muscle strength in the lower extremities and abdominal area.

DIAGNOSES

A high spinal anesthesia was confirmed by the patient loss of sensation and muscle strength in the lower extremities and abdominal area.

INTERVENTIONS

CSF lavage was performed for treatment.

OUTCOMES

After CSF lavage, the patient gradually returns to normal sensory and motor functions of lower limbs. On the fourth day, the patient sensed her physical function restoring gradually and was discharged uneventfully. At 4-month follow-up, the patient could have normal activities without obvious subsequent complications and any pain.

LESSONS

We conclude that CSF lavage could be a helpful maneuver to clear lidocaine and betamethasone and avoid potential nerve damage caused by an unintentional intrathecal injection during an epidural injection for the treatment of chronic low back pain.

Successful Control of Pain from Malignant Psoas Syndrome by Spinal Opioid with Local Anesthetic Agents

BACKGROUND

Malignant psoas syndrome (MPS) is a rare but distressing pain syndrome observed in advanced cancer patients. Pain due to MPS is often refractory to multimodal analgesic treatment, including opioid analgesics. As only 1 case demonstrating the efficacy of neuraxial analgesia in managing pain due to MPS has been reported, its role in MPS remains uncertain.

CASES

We present 3 cases demonstrating the successful management of pain due to MPS using spinal opioids with local anesthetic agents. All patients were under the care of the palliative care consultation service in an acute care hospital and refractory to multimodal analgesic treatment, including opioid, non-opioid, and adjuvant analgesics. Switching opioid administration to the epidural or intrathecal route with a local anesthetic agent provided good pain control in all 3 patients. Moreover, all patients showed improvements in both Palliative Performance Scale and Functional Independence Measure scores after starting a spinal opioid with a local anesthetic agent.

CONCLUSIONS

The findings in the present cases indicate neuraxial analgesia may be of benefit, in terms of managing pain and improving functional status, in MPS patients with insufficient pain control by multimodal analgesic treatment. Physicians should consider the use of neuraxial analgesia in cases of MPS where pain is uncontrolled with multimodal analgesic treatment to provide the best possible quality of life for patients with MPS.

Continuous Spinal Anesthesia for Obstetric Anesthesia and Analgesia

The widespread use of continuous spinal anesthesia (CSA) in obstetrics has been slow because of the high risk for post-dural puncture headache (PDPH) associated with epidural needles and catheters. New advances in equipment and technique have not significantly overcome this disadvantage. However, CSA offers an alternative to epidural anesthesia in morbidly obese women, women with severe cardiac disease, and patients with prior spinal surgery. It should be strongly considered in parturients who receive an accidental dural puncture with a large bore needle, on the basis of recent work suggesting significant reduction in PDPH when intrathecal catheters are used. Small doses of drug can be administered and extension of labor analgesia for emergency cesarean delivery may occur more rapidly compared to continuous epidural techniques.

Neurotoxicity Comparison of Two Types of Local Anaesthetics: Amide-Bupivacaine versus Ester-Procaine

Local anaesthetics (LAs) may lead to neurological complications, but the underlying mechanism is still unclear. Many neurotoxicity research studies have examined different LAs, but none have comprehensively explored the distinct mechanisms of neurotoxicity caused by amide- (bupivacaine) and ester- (procaine) type LAs. Here, based on a CCK8 assay, LDH assay, Rhod-2-AM and JC-1 staining, 2′,7′-dichlorohy-drofluorescein diacetate and dihydroethidium probes, an alkaline comet assay, and apoptosis assay, we show that both bupivacaine and procaine significantly induce mitochondrial calcium overload and a decline in the mitochondrial membrane potential as well as overproduction of ROS, DNA damage and apoptosis (P < 0.05). There were no significant differences in mitochondrial injury and apoptosis between the bupivacaine and procaine subgroups (P > 0.05). However, to our surprise, the superoxide anionic level after treatment with bupivacaine, which leads to more severe DNA damage, was higher than the level after treatment with procaine, while procaine produced more peroxidation than bupivacaine. Some of these results were also affirmed in dorsal root ganglia neurons of C57 mice. The differences in the superoxidation and peroxidation induced by these agents suggest that different types of LAs may cause neurotoxicity via different pathways. We can target more accurate treatment based on their different mechanisms of neurotoxicity.

Forty years later: Mitochondria as therapeutic targets in muscle diseases

The hypothesis that mitochondrial dysfunction can be a general mechanism for cell death in muscle diseases is 40 years old. The key elements of the proposed pathogenetic sequence (cytosolic Ca2+ overload followed by excess mitochondrial Ca2+ uptake, functional and then structural damage of mitochondria, energy shortage, worsened elevation of cytosolic Ca2+ levels, hypercontracture of muscle fibers, cell necrosis) have been confirmed in amazing detail by subsequent work in a variety of models. The explicit implication of the hypothesis was that it "may provide the basis for a more rational treatment for some conditions even before their primary causes are known" (Wrogemann and Pena, 1976, Lancet, 1, 672-674). This prediction is being fulfilled, and the potential of mitochondria as pharmacological targets in muscle diseases may soon become a reality, particularly through inhibition of the mitochondrial permeability transition pore and its regulator cyclophilin D.

Drug induced mitochondrial dysfunction: Mechanisms and adverse clinical consequences

Several commonly used medications impair mitochondrial function resulting in adverse effects or toxicities. Drug induced mitochondrial dysfunction may be a consequence of increased production of reactive oxygen species, altered mitochondrial permeability transition, impaired mitochondrial respiration, mitochondrial DNA damage or inhibition of beta-oxidation of fatty acids. The clinical manifestation depends on the specific drug and its effect on mitochondria. Given the ubiquitous presence of mitochondria and its central role in cellular metabolism, drug-mitochondrial interactions may manifest clinically as hepatotoxicity, enteropathy, myelosuppression, lipodystrophy syndrome or neuropsychiatric adverse effects, to name a few. The current review focuses on specific drug groups which adversely affect mitochondria, the mechanisms involved and the clinical consequences based on the data available from experimental and clinical studies. Knowledge of these adverse drug-mitochondrial interactions may help the clinicians foresee potential issues in individual patients, prevent adverse drug reactions or alter drug regimens to enhance patient safety.

Comparison of saddle, lumbar epidural and caudal blocks on anal sphincter tone: A prospective, randomized study

Objective

To compare the effects of saddle, lumbar epidural and caudal blocks on anal sphincter tone using anorectal manometry.

Methods

Patients undergoing elective anorectal surgery with regional anaesthesia were divided randomly into three groups and received a saddle (SD), lumbar epidural (LE), or caudal (CD) block. Anorectal manometry was performed before and 30 min after each regional block. The degree of motor blockade of the anal sphincter was compared using the maximal resting pressure (MRP) and the maximal squeezing pressure (MSP).

Results

The study analysis population consisted of 49 patients (SD group, n = 18; LE group, n = 16; CD group, n = 15). No significant differences were observed in the percentage inhibition of the MRP among the three regional anaesthetic groups. However, percentage inhibition of the MSP was significantly greater in the SD group (83.6 ± 13.7%) compared with the LE group (58.4 ± 19.8%) and the CD group (47.8 ± 16.9%). In all groups, MSP was reduced significantly more than MRP after each regional block.

Conclusions

Saddle block was more effective than lumbar epidural or caudal block for depressing anal sphincter tone. No differences were detected between lumbar epidural and caudal blocks.

Neuromyelitis optica after a spinal anaesthesia with bupivacaine

We report the case of a 53-year old woman who developed a neuromyelitis optica (NMO or Devic’s syndrome) after a spinal anaesthesia with bupivacaine. To our knowledge, the use of bupivacaine in human has not been associated to neurological complications like myelitis or NMO. The patho genesis of this complication will be discussed.

Revealing oxidative damage to enzymes of carbohydrate metabolism in yeast: An integration of 2D DIGE, quantitative proteomics, and bioinformatics

Clinical usage of lidocaine, a pro-oxidant has been linked with severe, mostly neurological complications. The mechanism(s) causing these complications is independent of the blockade of voltage-gated sodium channels. The budding yeast Saccharomyces cerevisiae lacks voltage-gated sodium channels, thus provides an ideal system to investigate lidocaine-induced protein and pathway alterations. Whole-proteome alterations leading to these complications have not been identified. To address this, S. cerevisiae was grown to stationary phase and exposed to an LC50 dose of lidocaine. The differential proteomes of lidocaine treatment and control were resolved 6 h post exposure using 2D DIGE. Amine reactive dyes and carbonyl reactive dyes were used to assess protein abundance and protein oxidation, respectively. Quantitative analysis of these dyes (⩾ 1.5-fold alteration, p ⩽ 0.05) revealed a total of 33 proteoforms identified by MS differing in abundance and/or oxidation upon lidocaine exposure. Network analysis showed enrichment of apoptotic proteins and cell wall maintenance proteins, while the abundance of proteins central to carbohydrate metabolism, such as triosephosphate isomerase and glyceraldehyde-3-phosphate dehydrogenase, and redox proteins superoxide dismutase and peroxiredoxin were significantly decreased. Enzymes of carbohydrate metabolism, such as phosphoglycerate kinase and enolase, the TCA cycle enzyme aconitase, and multiple ATP synthase subunits were found to be oxidatively modified. Also, the activity of aconitase was found to be decreased. Overall, these data suggest that toxic doses of lidocaine induce significant disruption of glycolytic pathways, energy production, and redox balance, potentially leading to cell malfunction and death.

The influence of adjuvants used in regional anesthesia on lidocaine-induced neurotoxicity in vitro

BACKGROUND

Neurotoxic properties of local anesthetics can rarely lead to irreversible neuronal damage as in cauda equina syndrome. Clinically, local anesthetics are often combined with adjuvants to improve or prolong the anesthetic effect, whereas the impact of such adjuvants on lidocaine-induced apoptosis is unclear. Therefore, we investigated the influence of different adjuvants on the neurotoxicity of lidocaine.

METHODS

Human neuroblastoma cells and primary rat astrocytes were incubated for 24 hrs with lidocaine at a toxic concentration alone and in combination with morphine, sufentanil, clonidine, epinephrine, neostigmine, ketamine, and midazolam. Subsequently, the rates of cell death and early apoptosis were measured by flow cytometry in neuroblastoma cells, whereas astrocyte viability was analyzed by mitochondrial activity assay. In addition, isobolograms were calculated to describe the additive effects of lidocaine with ketamine or midazolam, respectively.

RESULTS

Coadministration of lidocaine with sufentanil, clonidine, epinephrine, and neostigmine did not alter the rates of cell death compared with cells treated with lidocaine alone. Morphine improved the viability of astrocytes only at concentrations beyond those occurring clinically. In contrast, coincubation of lidocaine with ketamine or midazolam led to significantly increased rates of cell death. The combined toxicity of ketamine and lidocaine was additive, whereas the combined toxicity of midazolam and lidocaine was subadditive.

CONCLUSIONS

Sufentanil, clonidine, epinephrine, and neostigmine do not influence the neurotoxicity of lidocaine in vitro. Morphine may have some cytoprotective effect at concentrations greater than those seen intrathecally in humans. In contrast, ketamine and midazolam increase the neurotoxicity of lidocaine in vitro, presumably by additive induction of mitochondrial apoptosis.

A comparison of articaine and fentanyl-supplemented articaine for hemodialysis fistula creation under ultrasound-guided axillary block

The aim of this prospective randomized, double-blinded study was to evaluate the effect of fentanyl addition to articaine on the duration of sensory as well as motor blocks, and the duration of analgesia during hemodialysis fistula creation under ultrasound-guided axillary block. Fifty patients were randomly allocated to two groups, an articaine group (A), receiving 40 mL of articaine HCI (20 mg/mL) with 2 mL of isotonic sodium chloride solution, and an articaine-fentanyl group (AF), receiving 40 mL of articaine HCI (20 mg/mL) with 2 mL (100 µg) of fentanyl. The onset as well as the duration of sensory and motor blocks, the time necessary for first analgesic administration, the hemodynamic parameters, and the side effects were recorded. Three patients in Group A and two patients in Group AF due to incomplete block were excluded from the study. The duration of sensory and motor blocks was significantly longer in the AF group than in the A group. The first time for analgesic need was also significantly longer in group AF (363 ± 134 min) than in group A (244 ± 84 min) (p = 0.001). The addition of fentanyl did not improve the onset of sensory and motor block times. Hemodynamic parameters were similar in the two groups. In conclusion, the addition of fentanyl to articaine in axillary block prolongs the duration of sensory and motor blocks, as well as the time of first analgesic requirement.

Coupled obturator neurotomies and lidocaine intrathecal infusion to treat bilateral adductor spasticity and drug-refractory pain

Spastic diplegia is present in three-fourths of children with cerebral palsy, interfering with gait and frequently accompanied by severe pain. The authors report the case of a 28-year-old woman with history of perinatal hypoxia, who presented with cerebral palsy and severe spastic diplegia (Ashworth Scale Score 4, Tardieu Scale Score 5) and was confined to a wheelchair. She complained of pain in the left hip and knee with mixed neuropathic and somatic components. She consistently rated pain intensity as 10 of 10 on a visual analog scale, and her symptoms were resistant to multiple treatments. The patient underwent selective bilateral adductor myotomies and the implantation of an infusion pump for intrathecal lidocaine application. Postoperative control of pain and spasticity was dramatic (scores of 0 on the Ashworth, Tardieu, and visual analog scales) and persisted throughout a follow-up period of 36 months. This is the first report in the literature of combined selective neurotomies for the treatment of spasticity and chronic lidocaine subarachnoid infusion to treat associated pain. This therapy could represent an alternative to treat spasticity associated with neuropathic and somatic pain.

Cytotoxicity of local anesthetics in human neuronal cells

BACKGROUND

In addition to inhibiting the excitation conduction process in peripheral nerves, local anesthetics (LAs) cause toxic effects on the central nervous system, cardiovascular system, neuromuscular junction, and cell metabolism. Different postoperative neurological complications are ascribed to the cytotoxicity of LAs, but the underlying mechanisms remain unclear. Because the clinical concentrations of LAs far exceed their EC(50) for inhibiting ion channel activity, ion channel block alone might not be sufficient to explain LA-induced cell death. However, it may contribute to cell death in combination with other actions. In this study, we compared the cytotoxicity of six frequently used LAs and will discuss the possible mechanism(s) underlying their toxicity.

METHODS

In human SH-SY5Y neuroblastoma cells, viability upon exposure to six LAs (bupivacaine, ropivacaine, mepivacaine, lidocaine, procaine, and chloroprocaine) was quantitatively determined by the MTT-(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetra-odium bromide) colorimetry assay and qualitatively confirmed by fluorescence imaging, using the LIVE/DEAD assay reagents (calcein/AM and ethidium homodimer-1). In addition, apoptotic activity was assessed by measuring the activation of caspase-3/-7 by imaging using a fluorescent caspase inhibitor (FLICA). Furthermore, LA effects on depolarization- and carbachol-stimulated intracellular Ca(2+)-responses were also evaluated.

RESULTS

1) After a 10-min treatment, all six LAs decreased cell viability in a concentration-dependent fashion. Their killing potency was procaine < or = mepivacaine < lidocaine < chloroprocaine < ropivacaine < bupivacaine (based on LD(50), the concentration at which 50% of cells were dead). Among these six LAs, only bupivacaine and lidocaine killed all cells with increasing concentration. 2) Both bupivacaine and lidocaine activated caspase-3/-7. Caspase activation required higher levels of lidocaine than bupivacaine. Moreover, the caspase activation by bupivacaine was slower than by lidocaine. Lidocaine at high concentrations caused an immediate caspase activation, but did not cause significant caspase activation at concentrations lower than 10 mM. 3) Procaine and chloroprocaine concentration-dependently inhibited the cytosolic Ca(2+)-response evoked by depolarization or receptor-activation in a similar manner as a previous observation made with bupivacaine, ropivacaine, mepivacaine, and lidocaine. None of the LAs caused a significant increase in the basal and Ca(2+)-evoked cytosolic Ca(2+)-level.

CONCLUSION

LAs can cause rapid cell death, which is primarily due to necrosis. Lidocaine and bupivacaine can trigger apoptosis with either increased time of exposure or increased concentration. These effects might be related to postoperative neurologic injury. Lidocaine, linked to the highest incidence of transient neurological symptoms, was not the most toxic LA, whereas bupivacaine, a drug causing a very low incidence of transient neurological symptoms, was the most toxic LA in our cell model. This suggests that cytotoxicity-induced nerve injury might have different mechanisms for different LAs and different target(s) other than neurons.

Lidocaine induces apoptosis via the mitochondrial pathway independently of death receptor signaling

BACKGROUND

Local anesthetics, especially lidocaine, can lead to persistent cauda equina syndrome after spinal anesthesia. Recently, lidocaine has been reported to trigger apoptosis, although the underlying mechanisms remain unknown. To elucidate the pathway of lidocaine-induced apoptosis, the authors used genetically modified cells with overexpression or deficiencies of key regulators of apoptosis.

METHODS

Human Jurkat T-lymphoma cells overexpressing the antiapoptotic protein B-cell lymphoma 2 as well as cells deficient of caspase 9, caspase 8, or Fas-associated protein with death domain were exposed to lidocaine and compared with parental cells. The authors evaluated cell viability, mitochondrial alterations, cytochrome c release, caspase activation, and early apoptosis. Apoptosis was in addition investigated in neuroblastoma cells.

RESULTS

In Jurkat cells, lidocaine reduced viability, associated with a loss of the mitochondrial membrane potential. At low concentrations (3-6 mm) of lidocaine, caspase 3 was activated and release of cytochrome c was detected, whereas at higher concentrations (10 mm), no caspase activation was found. Apoptosis by lidocaine was strongly reduced by B-cell lymphoma-2 protein overexpression or caspase-9 deficiency, whereas cells lacking the death receptor pathway components caspase 8 and Fas-associated protein with death domain were not protected and displayed similar apoptotic alterations as the parental cells. Lidocaine also induced apoptotic caspase activation in neuroblastoma cells.

CONCLUSIONS

Apoptosis is triggered by concentrations of lidocaine occurring intrathecally after spinal anesthesia, whereas higher concentrations induce necrosis. The data indicate that death receptors are not involved in lidocaine-induced apoptosis. In contrast, the observation that B-cell lymphoma-2 protein overexpression or the lack of caspase 9 abolished apoptosis clearly implicates the intrinsic mitochondrial death pathway in lidocaine-induced apoptosis.

Gender differences in spinal cord injury are not estrogen-dependent

Recent attention has been given to gender differences in neurotrauma, and the anecdotal suggestion is that females have better outcomes than males, suggesting that circulating levels of estrogen (E(2)) may be neuroprotective. In order to address this issue, both young adult male and ovariectomized female rats were subjected to a T10 spinal cord injury (SCI), and E2 levels were maintained at chronic, constant circulating levels. Animals were clinically evaluated for locomotor changes using the Basso-Beattie-Bresnahan (BBB) scoring system. Morphologic differences were evaluated with unbiased stereology. Data analysis failed to reveal any significant benefit for the E2 therapy in either males or females. We did find a non-estrogen-dependent difference between male and female rats in length of injury, and percent of spared tissue, with female outcomes more favorable. These results suggest that E(2) does not provide a viable therapy following SCI.

Chronic Subarachnoid Administration of 1-(4chlorobenzoyl)-5methoxy-2methyl-1H-indole-3 Acetic Acid (Indomethacin): An Evaluation of Its Neurotoxic Effects in an Animal Model

Neuraxial administration of nonsteroid antiinflammatory drugs has been suggested as an alternative in the management of intractable pain, but there is little evidence that the neurotoxic effects of indomethacin by this route of administration have been evaluated. In this study, we evaluated histological neurotoxicity of indomethacin after its subarachnoid administration in guinea pigs. The hypothesis tested was "Does subarachnoid administration of indomethacin produce damage in the spinal cord of guinea pigs?" Ten male guinea pigs were anesthetized, and a polyamide catheter connected to a subcutaneous osmotic micro-pump was implanted at the L2-3 level. Animals were randomly assigned in 2 groups of 5 animals each. Indomethacin or saline solution was administered by continuous infusion (0.5 microL/h) for 14 days. Neurotoxicity was determined by spinal cord histopathology. There was no evidence of toxicity in the histological examinations of either group. These data suggest that subarachnoid administration of indomethacin infusion, at these doses, did not produce lesions typical of neurotoxicity in the spinal cord. We have concluded that epidural administration of indomethacin may be considered an alternative for application in human pain management, although more studies to determine its safety are required.

Clinical Pharmacology of Local Anesthetics

Whereas currently available local anesthetics may be suitable for intraoperative and in-hospital postoperative use, long-acting analgesia after outpatient procedures will require new techniques and drugs. Catheter delivery systems are rapidly gaining clinical acceptance and allow for great flexibility in dosing. Encapsulated local anesthetics can provide the slow release of drugs. Novel, long-acting local anesthetics are being investigated but are not yet ready for clinical use. In addition to the effects on the sodium channel, other actions of these novel compounds need to be explored, because both beneficial and detrimental effects may be induced with these compounds.

L’arachnoïdite médullaire adhésive : une complication tardive de l’analgésie péridurale obstétricale

A 30-year-old woman, G3P3, was progressively affected by spastic paraparesis with loss of sensitivity and urinary incontinence due to medullar adhesive arachnoiditis occurring five months after an epidural analgesia for repeat cesarean section. Magnetic resonance imaging showed a voluminous subarachnoid cyst and a septated syringomyelic cavitation attributed to metabisulfite, the preservative of epinephrine and to multiple lidocaine injections through the catheter in the postoperative period. Despite two decompressive neurosurgical operations, the neurological state of the patient continues to worsen.

Efficacy of Intrathecal Bupivacaine: How Important Is the Flow Rate?

We present two cases of cancer patients with intractable mechanical and visceral pain that was unrelieved with either comprehensive medical management or intrathecal morphine who received intrathecal bupivacaine. While the continuous administration of a seemingly significant daily dose neither relieved pain nor caused measurable clinical changes, the addition of small, presumably negligible bolus doses on top of the continuous infusion resulted in spectacular pain control, clear thermoanalgesic suspended block, and in one of the patients, significant hypotension. To the best of our knowledge, such an observation has neither been reported before nor can we provide a satisfactory explanation for it. However, we believe it may have significant implications for the treatment of some patients, in particular, cancer patients with mechanical pain that cannot be adequately relieved with morphine whatever the route of administration.

The use of intrathecal midazolam in humans: a case study of process

Early preclinical work demonstrated the potential role of spinal benzodiazepine pharmacology in regulating spinal nociceptive transmission. We review this preclinical activity and the evolving implementation of intrathecal midazolam in humans for pain management. Important elements in this development for use in humans are issues pertinent to safety and the preclinical reports that have increased our understanding of intrathecal midazolam toxicity. We seek to emphasize the time course of these studies and how they merged to provide enabling data that drove the clinical implementation. In the case of midazolam, we point to the potential issues that arose when preclinical safety data were unreasonably ignored and how consideration of preclinical safety data can serve to facilitate drug development by demonstrating reasonable safety profiles that document the minimal degree of potential risk to the patient. Issues that are of continuing relevance to the use of intrathecal midazolam, including issues of formulation and kinetics, are considered.

IMPLICATIONS

The intrathecal use of midazolam has evolved over 20 years though a combination of preclinical and clinical investigations. We review the time course of this development to define critical elements that should be pursued in reducing the risk associated with the clinical use of a novel spinal drug.

Spinal cord lesion after long-term intrathecal clonidine and bupivacaine treatment for the management of intractable pain

Long-term intrathecal drug administration using implanted pumps is increasingly used in the treatment of chronic refractory pain [Anderson and Burchiel 1999, Neurosurgery 44 (1999) 289; Krames 2002, Best Pract Res Clin Anaesthesiol 16 (2002) 619; Wallace 2002, Neurology 59 (2002) S18]. Extensive clinical experience over the last 15 years suggests that in selected cases the technique is safe, although infections, system malfunction and drug-related complications have been reported. In most cases, drug-related spinal cord injuries have resulted from the compression of a spinal inflammatory mass or abcess rather than from a direct neurotoxic effect. We report on a case of toxic spinal cord lesion occurring after more than 3 years of uneventful continuous infusion of a mixture of bupivacaine and clonidine.

Unexpected complication of attempted epidural anaesthesia: cauda equina syndrome

Cauda equina syndrome after regional anaesthesia is a serious and devastating complication. Its occurrence after epidural anaesthesia is rare. We report a 46-year-old male who received epidural anaesthesia for ureterorenoscopic lithotripsy and developed cauda equina syndrome postoperatively. Despite one failed attempt at entering the epidural space with an epidural needle resulting in dural puncture, an epidural catheter was inserted and 20 ml pH adjusted lignocaine 2% with 1:200,000 adrenaline injected via the catheter without untoward event. The possible causes of this complication are discussed. Fortunately, this patient recovered almost completely ten months later.

The induction of apoptosis by local anesthetics: a comparison between lidocaine and ropivacaine

IMPLICATIONS

This study suggests that lidocaine can induce apoptosis (detected by dual staining with Annexin V and propidium iodide) on T-cell line cultures in a time-dependent manner. This was not observed with ropivacaine.

Small-dose intrathecal lidocaine versus ropivacaine for anorectal surgery in an ambulatory setting

Spinal anesthesia with the local anesthetic lidocaine has come under scrutiny because it is associated with transient neurologic symptoms (TNS). We designed this study to prospectively compare the efficacy of ropivacaine as an alternative to lidocaine in patients undergoing elective outpatient anorectal procedures. Seventy-two patients were randomized to receive either hyperbaric lidocaine 25 mg with fentanyl 20 microg (n = 37) or hyperbaric ropivacaine 4 mg with fentanyl 20 microg (n = 35). Patients were examined for motor block, sensory block, and block duration. Patients were contacted at 24, 48, 72, and 168 h and questioned about their perceptions of pain after the spinal with specific questions designed to diagnose TNS. There were no patients with TNS in either group. There was no significant difference between the lidocaine and ropivacaine groups in any of the outcomes studied. In conclusion, intrathecal hyperbaric small-dose ropivacaine with fentanyl is an acceptable anesthetic for anorectal surgery.

IMPLICATIONS

In this prospective trial, small-dose ropivacaine with fentanyl was as effective as small-dose lidocaine with fentanyl for anorectal procedures in the ambulatory setting.

Patient care after discharge from the ambulatory surgical center

An important and often forgotten aspect of postoperative care occurs after the patient is discharged from the ambulatory surgical center. With more than 60% of all surgeries and procedures occurring on an ambulatory basis, what happens after the patient is no longer in continuous professional care is of concern to the ambulatory nurse. Numerous physical postoperative complaints are common and expected sequelae of anesthesia and surgery in the ambulatory patient. In this article, important postdischarge complications are reviewed and contemporary management options discussed. The information contained in this review article is valuable to the provider in educating patients regarding their anticipated course of postoperative recovery.

OBJECTIVES

-Based on the content of this article, the reader should be able to (1) identify important postdischarge complications to provide patients with comprehensive discharge instructions regarding their continued recovery at home; (2) discuss contemporary management options available to treat postdischarge complications; (3) realize the incidence of specific postdischarge complications and how that relates to patient satisfaction with the surgical experience; (4) recognize signs and symptoms of postdischarge complications; and (5) identify risk factors of patients for developing specific complications in the postoperative phase.