Prolonged severe withdrawal symptoms after acute-on-chronic baclofen overdose

Transient alteration of consciousness in spinal cord injury secondary to Baclofen use: a case report

INTRODUCTION

Oral baclofen is commonly used for spasticity management, especially with neurogenic bladder in spinal cord injury (SCI). A less common side effect of baclofen is transient alterations of consciousness, which can easily be confused for altered mental status secondary to orthostatic hypotension in SCI.

CASE PRESENTATION

A 43-year-old man with an acute SCI secondary to an aortic dissection was found to have episodes of confusion after titrating oral baclofen from 5 mg three times per day to 10 mg three times per day at an acute rehabilitation facility. Orthostatic hypotension was initially suspected as the cause of transient alterations of consciousness; however, he was never found to be hypotensive during these episodes. His confusion resolved several days after discontinuation of baclofen.

DISCUSSION

Although, confusion and lightheadedness in SCI are commonly caused by orthostatic hypotension, it is important for physicians to be cognizant of baclofen's side effects, which increase in the setting of acute kidney injury (AKI). If an adverse effect is suspected, baclofen should be tapered while remaining observant for signs of baclofen withdrawal, which can be life-threatening. This case report is a reminder for clinicians to be aware of the uncommon adverse effects of baclofen when initiating therapy in SCI, especially in patients with AKI and neurogenic bladders.

Recommendations from the EXTRIP workgroup on extracorporeal treatment for baclofen poisoning

Baclofen toxicity results from intentional self-poisoning ("acute baclofen poisoning") or accumulation of therapeutic dose in the setting of impaired kidney function. Standard care includes baclofen discontinuation, respiratory support and seizure treatment. Use of extracorporeal treatments (ECTRs) is controversial. To clarify this, a comprehensive review of the literature on the effect of ECTRs in baclofen toxicity was performed and recommendations following EXTRIP methods were formulated based on 43 studies. (1 comparative cohort, 1 aggregate results cohort, 1 pharmacokinetic modeling, and 40 patient reports or series). Toxicokinetic data were available for 20 patients. Baclofen's dialyzability is limited by a high endogenous clearance and a short half-life in patients with normal kidney function. The workgroup assessed baclofen as "Moderately dialyzable" by intermittent hemodialysis for patients with normal kidney function (quality of evidence C) and "Dialyzable" for patients with impaired kidney function (quality of evidence C). Clinical data were available for 25 patients with acute baclofen poisoning and 46 patients with toxicity from therapeutic baclofen in kidney impairment. No deaths or sequelae were reported. Mortality in historical controls was rare. No benefit of ECTR was identified in patients with acute baclofen poisoning. Indirect evidence suggests a benefit of ECTR in reducing the duration of toxic encephalopathy from therapeutic baclofen in kidney impairment. These potential benefits were balanced against added costs and harms related to the insertion of a catheter, the procedure itself, and the potential of baclofen withdrawal. Thus, the EXTRIP workgroup suggests against performing ECTR in addition to standard care for acute baclofen poisoning and suggests performing ECTR in toxicity from therapeutic baclofen in kidney impairment, especially in the presence of coma requiring mechanical ventilation.

Enteral baclofen withdrawal managed with intravenous dexmedetomidine: A case report

PURPOSE

Acute enteral baclofen withdrawal can be clinically severe if not identified and managed appropriately. Treatment of baclofen withdrawal includes supportive care and reinitiation of baclofen. There are limited pharmacotherapeutic interventions available to manage symptoms of acute enteral baclofen withdrawal, especially in nonintubated patients.

SUMMARY

We describe a 61-year-old Caucasian male with a past medical history of chronic back pain and spinal stenosis who was admitted to the medical intensive care unit with confusion, insomnia, agitation, delirium, and auditory and visual hallucinations. For control of agitation, the patient was administered 10 mg of i.v. haloperidol, 1 mg of i.v. lorazepam, and 14 mg of i.v. midazolam, with minimal improvement noted; therefore, dexmedetomidine was initiated, which led to clinical resolution of his symptoms. Upon further investigation it was determined that the patient was taking approximately 10 baclofen 20-mg tablets a day. According to his pharmacy records, he had filled prescriptions for a total of 738 baclofen tablets in the previous 12 weeks. The patient's presentation and sudden discontinuation of high-dose baclofen led to a diagnosis of baclofen withdrawal. Baclofen was subsequently restarted, and dexmedetomidine was weaned over 36 hours.

CONCLUSION

Dexmedetomidine controlled this patient's agitation and delirium without suppressing his respiratory drive and should be considered for management of acute enteral baclofen withdrawal.

Toxicologic Confounders of Brain Death Determination: A Narrative Review

The aim of this narrative review is to describe the toxicologic confounders of brain death currently reported in the literature to offer guidance for physicians assessing brain death after a toxic exposure. We established an a priori definition of a “brain death mimic” as an unresponsive, intubated patient missing some, but not all brainstem reflexes. We completed a review of the literature utilizing MEDLINE and EMBASE to find case reports of patients of all ages in English, French, and Spanish meeting the criteria and hand searched the references of the results. We recorded xenobiotic dose, duration of physical exam suggesting brain death, and how the cases failed to meet full brain death criteria, when available. Fifty-six cases representing 19 different substances met the a priori definition of brain death mimic. Xenobiotic toxicities included: snake envenomation (13), baclofen (11), tricyclic antidepressants (8), bupropion (7), alcohols (4), antiepileptic agents (3), barbiturates (2), antidysrhythmics (2), organophosphates (2), and one case each of magnesium, succinylcholine, tetrodotoxin, and zolpidem. All patients except one survived to discharge and the majority at their baseline physical health. The most common means by which the cases failed brain death examination prerequisites was via normal neuroimaging. The xenobiotics in this review should be considered in cases of poisoning resulting in loss of brainstem reflexes and addressed before brain death determination. Brain death diagnosis should not be pursued in the setting of normal cerebral imaging or incomplete evaluation of brain death prerequisites.

Toxicological considerations in the prescription of baclofen for the treatment of substance use disorders

Introduction: For many years, applications for baclofen have widened in the treatment of substance abuse disorder (SUD), mainly alcohol use disorder, with a growing rate of off-label prescriptions in Europe. Clinical effects seem to be both a decrease of craving and anxiety, leading to a decrease of drug or alcohol consumption. We described baclofen poisoning circumstances, therapeutic options and outcomes when used in substance use disorders.Areas covered: This review summarizes the toxicological considerations where baclofen was prescribed in humans for substance use or abuse disorder in randomized clinical trials, case series, case reports and observational studies between 1990 and 2020 according to the Preferred Reporting Items for Systemic reviews and Meta-Analysis.Expert opinion: The most frequent cause of severe intoxication is self-poisoning. A dose above 180 mg are expected to cause severe toxicity and death. The treatment is only symptomatic as no antidote is available. Off-label prescription remains unsafe because the optimal dose is not known and varies greatly between patients. As SUD are frequently associated with psychiatric disorders and such patients may have suicidal thoughts, the risk of self-poisoning is high. Potential co-ingestants should also be considered, especially CNS depressants, and they need to be closely monitored.

Baclofen-induced encephalopathy in overdose - Modeling of the electroencephalographic effect/concentration relationships and contribution of tolerance in the rat

Baclofen, a γ-amino-butyric acid type-B receptor agonist with exponentially increased use at high-dose to facilitate abstinence in chronic alcoholics, is responsible for increasing poisonings. Baclofen overdose may induce severe encephalopathy and electroencephalographic (EEG) abnormalities. Whether prior prolonged baclofen treatment may influence the severity of baclofen-induced encephalopathy in overdose has not been established. We designed a rat study to characterize baclofen-induced encephalopathy, correlate its severity with plasma concentrations and investigate the contribution of tolerance. Baclofen-induced encephalopathy was assessed using continuous EEG and scored based on a ten-grade scale. Following the administration by gavage of 116 mg/kg baclofen, EEG rapidly and steadily impaired resulting in the successive onset of deepening sleep followed by generalized periodic epileptiform discharges and burst-suppressions. Thereafter, encephalopathy progressively recovered following similar phases in reverse. Periodic triphasic sharp waves, non-convulsive status epilepticus and even isoelectric signals were observed at the most critical stages. Prior repeated baclofen administration resulted in reduced severity (peak: grade 7 versus 9; peak effect length: 382 ± 40 versus 123 ± 14 min, P = 0.008) and duration of encephalopathy (18 versus > 24 h, P = 0.0007), supporting the acquisition of tolerance. The relationship between encephalopathy severity and plasma baclofen concentrations fitted a sigmoidal E_max model with an anticlockwise hysteresis loop suggesting a hypothetical biophase site of action. The baclofen concentration producing a response equivalent to 50% of E_max was significantly reduced (8947 μg/L, ±11.3% versus 12,728 μg/L, ±24.0% [mean, coefficient of variation], P = 0.03) with prior prolonged baclofen administration. In conclusion, baclofen overdose induces early-onset and prolonged marked encephalopathy that is significantly attenuated by prior repeated baclofen treatment. Our findings suggest a possible role for the blood-brain barrier in the development of tolerance; however, its definitive involvement remains to be demonstrated.

Baclofen Toxicity in Kidney Disease

Baclofen, a commonly prescribed muscle relaxant, is primarily excreted via the kidneys; toxicity is a potentially serious adverse outcome in patients with decreased kidney function. We describe a patient with end-stage kidney disease receiving hemodialysis who developed neurotoxicity and hemodynamic instability after receiving baclofen for muscle spasms. In this case, prompt recognition of baclofen toxicity and urgent hemodialysis were effective in reversing this toxicity. This case is used to examine the pharmacokinetics and pathophysiology of baclofen toxicity and discuss appropriate diagnosis and management of baclofen toxicity. We recommend reducing the baclofen dose in patients who have moderately reduced kidney function (estimated glomerular filtration rate, 30-60mL/min/1.73m²) and avoiding use in patients with severely reduced kidney function (estimated glomerular filtration rate < 30mL/min/1.73m²) or on renal replacement therapy.

Baclofen overdose mimicking anoxic encephalopathy: a case report and review of the literature

A patient who has overdosed on baclofen can present with significant neurological symptoms suggestive of a serious brain insult, but with appropriate diagnosis and treatment they often fully recover within 72 h. If the patient had been maintained on chronic baclofen therapy prior to the overdose, one must be watchful for signs of baclofen withdrawal as recovery from the overdose occurs.

Application of high-resolution mass spectrometry to determination of baclofen in a case of fatal intoxication

The study focused on the application of high-resolution mass spectrometry (HRMS) to postmortem toxicological analysis. Fast and simple sample preparation involved precipitation with acetonitrile, removal of phospholipids using special columns and filtration. Qualitative and quantitative analyses were performed using ultra-performance liquid chromatography coupled with quadrupole time-of–flight mass spectrometry. The method was validated by determining the limit of quantification, precision, recovery and matrix effect. The use of a high-resolution spectrometer allowed us to determine the precise masses of the fragments of interest and to suggest the fragmentation pathway of baclofen. The usefulness, effectiveness and assets of the procedure were confirmed by an authentic case of a 25-year-old woman fatally intoxicated with baclofen who was found dead in her apartment. Toxicological analysis of postmortem blood samples demonstrated that the baclofen concentration was 30.7 μg/mL. In only one published case describing fatal baclofen intoxication were no other xenobiotics (that could interact with baclofen) found. To our knowledge, this is the first report dealing with analysis of baclofen by HRMS.

Novel psychoactive substances of interest for psychiatry

Novel psychoactive substances include synthetic cannabinoids, cathinone derivatives, psychedelic phenethylamines, novel stimulants, synthetic opioids, tryptamine derivatives, phencyclidine-like dissociatives, piperazines, GABA-A/B receptor agonists, a range of prescribed medications, psychoactive plants/herbs, and a large series of performance and image enhancing drugs. Users are typically attracted by these substances due to their intense psychoactive effects and likely lack of detection in routine drug screenings. This paper aims at providing psychiatrists with updated knowledge of the clinical pharmacology and psychopathological consequences of the use of these substances. Indeed, these drugs act on a range of neurotransmitter pathways/receptors whose imbalance has been associated with psychopathological conditions, including dopamine, cannabinoid CB1, GABA-A/B, 5-HT2A, glutamate, and k opioid receptors. An overall approach in terms of clinical management is briefly discussed.

Morbidity following lower extremity fractures in men with spinal cord injury

The Veterans Affairs Spinal Cord Dysfunction Registry from 2002 to 2007 was reviewed to determine whether men with spinal cord injury (SCI) and lower extremity fractures had an increased risk of complications compared to those without fractures. We determined that fractures are associated with significant consequences, particularly during the first month postfracture.

INTRODUCTION

Despite increasing longevity, patients with SCI have a substantial number of illnesses and comorbid conditions. Lower extremity fractures are frequent events in these patients. However, whether these fractures are associated with any increased risk of complications in SCI is not certain. The purpose of this report was to determine the impact of lower extremity fractures on morbidities in men with SCI.

METHODS

A population-based, nested, case-control (1,027 cases and 1,027 propensity-matched controls) of men enrolled in the Veterans Affairs Spinal Cord Dysfunction Registry from fiscal years 2002 to 2007 was reviewed to determine whether lower extremity fractures were associated with an increased risk for complications.

RESULTS

In propensity score models matched for demographic (age, race) and SCI-related injury factors (level/completeness of SCI), Veterans Affairs-service connection status, and comorbidities, at 1 month following the fracture, there was an increased risk for respiratory infections, pressure ulcers, urinary tract infections, thromboembolic events, depression, and delirium (p ≤ 0.03 for all). Over 12 months, the only complication more common in fracture cases was pressure ulcers (p < 0.01), with an absolute difference of less than 2 % when compared to controls. There was no significant increased risk of cardiac arrhythmias at any time examined following fracture (≥0.12).

CONCLUSIONS

Lower extremity fractures are associated with significant consequences in men with SCI during the first month postfracture, but they do not persist for a long term, except for pressure ulcers. Targeted interventions to prevent complications should be considered following lower extremity fractures in SCI, particularly in the first month following fracture.

Neurotoxic emergencies

This article is intended for clinicians treating neurotoxic emergencies. Presented are causative agents of neurotoxic emergencies, many of which are easily mistaken for acute psychiatric disorders. Understanding the wide variety of agents responsible for neurotoxic emergencies and the neurotransmitter interactions involved will help the psychiatrist identify and treat this challenging population.

Separate and combined effects of the GABA(B) agonist baclofen and Δ9-THC in humans discriminating Δ9-THC

BACKGROUND

Our previous research with the GABA reuptake inhibitor tiagabine suggested the involvement GABA in the interoceptive effects of Δ9-THC. The aim of the present study was to determine the potential involvement of the GABA(B) receptor subtype by assessing the separate and combined effects of the GABA(B)-selective agonist baclofen and Δ9-THC using pharmacologically specific drug-discrimination procedures.

METHODS

Eight cannabis users learned to discriminate 30 mg oral Δ9-THC from placebo and then received baclofen (25 and 50mg), Δ9-THC (5, 15 and 30 mg) and placebo, alone and in combination. Self-report, task performance and physiological measures were also collected.

RESULTS

Δ9-THC functioned as a discriminative stimulus, produced subjective effects typically associated with cannabinoids (e.g., High, Stoned, Like Drug), elevated heart rate and impaired rate and accuracy on a psychomotor performance task. Baclofen alone (50 mg) substituted for the Δ9-THC discriminative stimulus, and both baclofen doses shifted the discriminative-stimulus effects of Δ9-THC leftward/upward. Similar results were observed on other cannabinoid-sensitive outcomes, although baclofen generally did not engender Δ9-THC-like subjective responses when administered alone.

CONCLUSIONS

These results suggest that the GABA(B) receptor subtype is involved in the abuse-related effects of Δ9-THC, and that GABA(B) receptors were responsible, at least in part, for the effects of tiagabine-induced elevated GABA on cannabinoid-related behaviors in our previous study. Future research should test GABAergic compounds selective for other GABA receptor subtypes (i.e., GABA(A)) to determine the contribution of the different GABA receptors in the effects of Δ9-THC, and by extension cannabis, in humans.

Baclofen intoxication: a "fun drug" causing deep coma and nonconvulsive status epilepticus--a case report and review of the literature

The number of reports on baclofen intoxication has increased in recent years. We report a 15-year-old boy who was referred in a state of deep coma (Glasgow Coma Scale = 3). On clinical examination, he showed sinus bradycardia with normal blood pressure. On admission to the hospital, he presented intermittent short episodes of generalized tonic-clonic seizures. While results of imaging procedures and initial toxicological screening (including standard HPLC analysis and urine test) were negative, a nonconvulsive status epilepticus was diagnosed by electroencephalography (EEG). Identification of baclofen as causative agent was possible after the boy's father reported abusive baclofen intake. Subsequent toxicological target analysis of blood and urine samples confirmed the excessive intake of baclofen and showed a typical elimination pattern with a secondary release. Following 112 h of mechanical ventilation, the boy rapidly regained consciousness and recovered normal neurological behavior.

CONCLUSIONS

The present case demonstrates the importance of considering baclofen overdosage in cases of severe coma in combination with an abnormal EEG pattern and sinus bradycardia with normal blood pressure levels, in particular as the substance is popular in internet reports promoting baclofen as a rather harmless "fun drug." Furthermore, it underlines the difficulty to identify baclofen as a causative agent without anamnestic information. Nevertheless, by reviewing existing literature on oral baclofen overdosage, it is possible to picture a nearly specific pattern of clinical symptoms in baclofen intoxication.

Seizures in patients with multiple sclerosis: epidemiology, pathophysiology and management

Seizures have been recognized to occur in multiple sclerosis (MS) since early descriptions of the disease. Various studies have attempted to determine the incidence and prevalence of seizures in MS; although they differ in the reported prevalence, seizures do appear to be more common in MS cohorts than in the general population. The pathological underpinning of seizures in MS remains indeterminate. Cortical and subcortical demyelination and inflammation may explain the increased frequency of seizures in MS, although this hypothetical correlation remains to be proven. Management of seizures in MS is similar to the management of seizures in other patients. Consideration of the underlying neurological deficits related to MS may be necessary, and dosages of antiepileptic drugs should be adjusted if increased sensitivity to the adverse effects of these agents or interaction with other centrally acting medications is suspected. The prognosis of epilepsy in patients with MS remains uncertain, with some studies suggesting a more favourable prognosis than others.

Chemically Induced Seizures

Drug- and toxin-associated seizures (DTS) may result from exposure to a wide variety of agents. Most DTS can be managed with supportive care. First-line anticonvulsant therapy should include benzodiazepines, unless agents require a specific antidote. Phenytoin is generally not expected to be useful for DTS and in some instances may be harmful. In this article the authors discuss the pathophysiology of DTS, the potential differential diagnosis, and the clinical presentation. They also review selected agents that cause DTS and provide an overview of how the clinician should approach the management of patients who have DTS.

Drug- and toxin-associated seizures

Drug- and toxin-associated seizures may result from exposure to a wide variety of agents. Obtaining a comprehensive history behind the exposure is generally more helpful than diagnostic testing. Most DTS may be managed with supportive care, including benzodiazepines, except in the case of agents that require a specific intervention or antidote.

Delirium Associated With Baclofen Withdrawal: A Review of Common Presentations and Management Strategies

The authors reviewed 23 published cases of psychiatric symptoms in association with baclofen withdrawal. Delirium, and not other functional psychiatric conditions, arose secondarily from abrupt baclofen cessation. Vulnerability to baclofen-withdrawal delirium appeared to be greater in individuals who received chronic baclofen therapy. Baclofen-withdrawal delirium can be difficult to distinguish from delirium of other etiologies, and unrecognized and inadequately treated baclofen-withdrawal delirium is associated with significant morbidity and mortality. Complete resolution of delirium symptoms was possible with reinstatement of baclofen. The clinical management of patients experiencing baclofen-withdrawal delirium includes supportive interventions to reduce complications of delirium until symptoms resolve.

Intrathecal baclofen overdose followed by withdrawal: clinical and EEG features

Intrathecal baclofen therapy is increasingly used to alleviate medically intractable spasticity in children with cerebral palsy, spinal cord injuries, and generalized dystonia. Complications like overdose or withdrawal can occur and could be the result of pump malfunction (device-related) or refilling and programming mistakes (human errors). This report describes a case, with emphasis on electroencephalographic changes, of a 12-year old male on long-term intrathecal baclofen therapy who had sequential occurrence of both acute inadvertent baclofen overdose followed by withdrawal symptoms. During baclofen intoxication, electroencephalography documented periodic generalized epileptiform discharges, occasionally followed by intermittent electro-decremental responses on a background of diffuse delta slowing (1-2 Hz). During withdrawal, mild generalized slowing during wakefulness was observed along with the appearance of high-amplitude, sharply contoured delta activity resembling frontal intermittent rhythmic delta activity in sleep. To our knowledge, this temporal profile of electroencephalographic features during baclofen intoxication followed by withdrawal has not been described before in pediatric patients. It is important for treating physicians to recognize the evolution of this electroencephalographic pattern in order to avoid misinterpretation of diagnosis and prognosis.

A benefit-risk assessment of baclofen in severe spinal spasticity

Baclofen is used for treatment of the spasticity of spinal origin that is a common sequela of spinal cord injury and multiple sclerosis; spasticity occurs in about 50% of patients affected by these disorders. In open-label studies of oral baclofen, the drug improved spasticity in 70-87% of patients; additionally, improvement in spasms was reported in 75-96% of patients. In double-blind, crossover, placebo-controlled trials, baclofen was reported to be effective, producing statistically significant improvements in spasticity. Tizanidine is the antispasticity drug that has been most widely compared with oral baclofen; studies have generally found the two drugs to have equivalent efficacy. However, tizanidine has better tolerability, in particular weakness was reported to be occur less frequently with tizanidine than with baclofen. The main adverse effects of oral baclofen include: sedation or somnolence, excessive weakness, vertigo and psychological disturbances. The incidence of adverse effects is reported to range from 10% to 75%. The majority of adverse effects are not severe; most are dose related, transient and/or reversible. The main risks of oral baclofen administration are related to withdrawal: seizures, psychic symptoms and hyperthermia can occur. These symptoms improve after the reintroduction of baclofen, usually without sequelae. When not related to withdrawal; these symptoms mainly present in patients with brain damage and in the elderly. The limited data on baclofen toxicity in patients with renal disease suggest that administration of the drug in these persons may carry an unnecessarily high risk. Intrathecal baclofen is indicated for use in patients with spasticity of spinal origin unresponsive to treatment with maximum doses of oral baclofen, tizanidine and/or dantrolene. The benefits of continuous intrathecal baclofen infusion have been demonstrated: >80% and >65% of patients have improvement in tone and spasms, respectively. The main risks of intrathecal baclofen infusion are symptoms related to overdose or withdrawal; the latter is more important because of the associated severe effects on clinical status and the possibility of death, but it is responsive to rapid treatment. Overdose primarily arises from drug test doses or human error during refill and programming of the pump, and withdrawal most commonly occurs as a result of a problem with the delivery system. Since the adverse consequences do not exceed the benefits of oral and intrathecal baclofen for patients with spinal spasticity, the benefit/risk assessment is favourable.

Intrathecal baclofen withdrawal syndrome- a life-threatening complication of baclofen pump: a case report

Background

Intrathecal baclofen pump has been used effectively with increasing frequency in patients with severe spasticity, particularly for those patients who are unresponsive to conservative pharmacotherapy or develop intolerable side effects at therapeutic doses of oral baclofen. Drowsiness, nausea, headache, muscle weakness, light-headedness and return of pretreatment spasticity can be caused by intrathecal pump delivering an incorrect dose of baclofen. Intrathecal baclofen withdrawal syndrome is a very rare, potentially life-threatening complication of baclofen pump caused by an abrupt cessation of intrathecal baclofen.

Case presentation

A 24-year-old man with a past medical history of cerebral palsy and spastic quadriparesis developed hyperthermia, disseminated intravascular coagulation, rhabdomyolysis, acute renal failure and multisystem organ failure leading to a full-blown intrathecal baclofen withdrawal syndrome. Intrathecal baclofen pump analysis revealed that it was stopped due to some programming error. He was treated effectively with supportive care, high-dose benzodiazepines and reinstitution of baclofen pump.

Conclusion

The episodes of intrathecal baclofen withdrawal syndrome are mostly caused by preventable human errors or pump malfunction. Educating patients and their caregivers about the syndrome, and regular check-up of baclofen pump may decrease the incidence of intrathecal baclofen withdrawal syndrome. Oral baclofen replacement may not be an effective method to treat or prevent intrathecal baclofen withdrawal syndrome. Management includes an early recognition of syndrome, proper intensive care management, high-dose benzodiazepines and prompt analysis of intrathecal pump with reinstitution of baclofen.

Interaction of γ-aminobutyric acid receptor type B receptors and calcium channels in nociceptive transmission studied in the mouse hemisected spinal cord in vitro: withdrawal symptoms related to baclofen treatment

An in vitro mouse hemisected spinal cord was used to characterize the gamma-aminobutyric acid receptor type B (GABA(B)) modulation of the ventral root potential (VRP) in response to electrical stimulation of the dorsal root (DR). Low-intensity (LI) and high-intensity (HI) stimulation induced VRPs with progressively higher amplitude and duration. Repetitive HI-stimulation of the DR (1-10 Hz) produced windup. The selective GABA(B) receptor agonist, CGP35024, inhibited the VRPs in a dose-dependent manner. The inhibitory action of CGP35024 was blocked by CGP52432, a potent GABA(B) receptor antagonist. Following washout of the GABA(B) receptor agonist, VRPs and windup were significantly enhanced. The rebound increase of the VRP following removal of CGP35024 was also blocked by the GABA(B) receptor antagonist, CGP52432. This phenomenon is not linked to receptor desensitization, but rather due to GABA(B) receptor-induced hyperactivity of N-, P/Q-type Ca(2+) channels, as omega-CgTx GVIA and MVIIC abolished/prevented the increase. The 'rebound' enhancement of the spinal transmission after exposure to GABA(B) agonists sheds light on the possible mechanism of the severe withdrawal effects after abrupt termination of baclofen treatment in patients suffering from multiple sclerosis.

Treatment of Chronic Pain

Chronic pain is a symptom associated with ongoing physical or mental illness or a combination of both that may not have a clear, identifiable pathophysiology. Assessment of chronic pain varies in the clinical presentation related to age, gender, racial, and cultural differences. Headache, low back pain, musculoskeletal pain, and neuropathic pain are the most common types of chronic pain complaints by patients. Pharmacologic therapy is based on best practice standards, published clinical trials, and guidelines by professional organizations. Current medications reviewed include opioids, anticonvulsants, antidepressants, clonidine, local anesthetics, muscle relaxants, N-methyl-D-aspartate antagonists, and nonsteroidal anti-inflammatory drugs.

Intrathecal baclofen withdrawal mimicking sepsis

Baclofen (Lioresal) is a drug of choice to treat spasticity and is increasingly being administered intrathecally via an implantable pump in cases refractory to oral therapy. Emergency physicians will likely treat patients with baclofen withdrawal or overdose as this treatment becomes more widespread. The syndrome of baclofen withdrawal presents with altered mental status, fever, tachycardia, hypertension or hypotension, seizures, and rebound spasticity, and may be fatal if not treated appropriately. Baclofen withdrawal may mimic other diseases including sepsis, meningitis, autonomic dysreflexia, malignant hyperthermia, or neuroleptic malignant syndrome. Treatment consists of supportive care, reinstitution of baclofen, benzodiazepines, and diagnosis and eventual repair of intrathecal pump and catheter malfunction.

Withdrawal syndromes

The pathophysiology of substance withdrawal is elucidated by a review of classic and cutting-edge research. The manifestation and evaluation of the associated withdrawal syndromes from ethanol, sedative-hypnotics, opioids, and baclofen, are compared. The general management of and pharmacotherapy for these patients are discussed.

Effects of muscle relaxants on EEG, ABR and EMG in rabbits

The effects of baclofen and pancuronium bromide on evoked electromyogram (EMG), cortical electroencephalogram (EEG) and auditory brainstem responses (ABR) were studied in pentobarbital anesthetized normal rabbits. Evoked EMG was measured in the gastrocnemius muscle by electrical stimulation of the sciatic nerve. Intravenous injection of baclofen decreased EEG and arterial blood pressure and light reflex, however, it had no significant influence on EMG or ABR at doses of 10 and 20 mg/kg/h. Pancuronium bromide immediately inhibited respiration, decreased EEG and EMG, however, it had no significant influence on arterial blood pressure, ABR, or light reflex, at doses of 0.4 and 1.0 mg/kg/h in anesthetized rabbits. ABR waves were observed until just before cardiac arrest with both of the muscle relaxants. It is suggested that ABR are not influenced by central or peripheral muscle relaxants, or by pentobarbital.

Baclofen and ethanol ingestion: a case report

The number of reported cases of skeletal muscle relaxant ingestion has been increasing in the United States, although fatalities are rare. A 30-year-old women ingested 300 mg of baclofen and ethanol. She was able to ambulate into the Emergency Department (ED) 50 min later, but within 30 min post-arrival had a Glasgow Coma Score of 3. She was treated with supportive care including mechanical ventilation for 36 h. Her neurologic status returned to her previous state. Coma may occur rapidly after baclofen overdose, and the respiratory depression may be exacerbated by the co-ingestion of ethanol. Primary importance in the treatment of such ingestions should be placed on maintenance of an airway and respiratory support.