Oral baclofen in cerebral palsy: possible seizure potentiation?

Baclofen Toxicity Mimicking Brain Death: A Case Report of a Pediatric Patient

BACKGROUND

Baclofen is commonly used in both pediatric and adult patients to treat spasticity secondary to spinal cord and cerebral pathology. A broad range of symptoms and severity of baclofen toxicity have been described. However, to our knowledge, there are no reports to date of baclofen toxicity mimicking brain death in pediatric patients.

OBJECTIVE

We reviewed the presentation, clinical course, diagnostic studies including imaging and electroencephalography, and outcome of a patient with transient coma and loss of brainstem reflexes mimicking brain death secondary to baclofen toxicity.

METHODS

During a baclofen pump refill, a 12-year-old boy with cerebral palsy had inadvertent injection of 12,000 μg of baclofen into the pocket around his pump. Within an hour, he presented with acute altered mental status that rapidly progressed to a comatose state with absent brainstem reflexes.

RESULTS

After appropriate management, the patient returned to his neurological baseline by hospital day 3.

DISCUSSION

We reviewed the literature for varying presentations of baclofen toxicity and associated electroencephalography findings, mechanism of overdose, and different management options. In this case, the mechanism of baclofen toxicity was suspected to be secondary to extravasation from the pump pocket and subsequent systemic absorption.

CONCLUSIONS

Patients with baclofen toxicity may have a dramatic presentation and an initial examination mimicking brain death. Given its rarity, this clinical entity may not be readily recognized, and there is potential for misinterpretation of diagnosis and prognosis. It is important for physicians to be familiar with this clinical scenario to avoid false declaration of brain death.

Pharmacological Management of Spasticity in Children With Cerebral Palsy

Cerebral palsy (CP), a nonprogressive disease of the central nervous system, is the most common motor disability in childhood. Patients with CP often have a multitude of associated comorbidities, including impact on muscle tone. There are four main types of CP, with spastic as the most commonly diagnosed. Reduction in spasticity is important because it can affect not only the patient's quality of life, functional abilities, and well-being but also the lives of caregivers. The American Academy of Neurology and Child Neurology Society released a practice parameter regarding the pharmacological management of CP-related spasticity in 2010. Since then, data have been published evaluating the safety and efficacy of oral and parenteral medications to manage spasticity. This continuing education review evaluates the available safety and efficacy evidence for oral and parenteral pharmacological agents used to reduce spasticity in children with CP and provides a reference for practitioners managing these patients.

Pain Assessment and Treatment in Children With Significant Impairment of the Central Nervous System

Pain is a frequent and significant problem for children with impairment of the central nervous system, with the highest frequency and severity occurring in children with the greatest impairment. Despite the significance of the problem, this population remains vulnerable to underrecognition and undertreatment of pain. Barriers to treatment may include uncertainty in identifying pain along with limited experience and fear with the use of medications for pain treatment. Behavioral pain-assessment tools are reviewed in this clinical report, along with other strategies for monitoring pain after an intervention. Sources of pain in this population include acute-onset pain attributable to tissue injury or inflammation resulting in nociceptive pain, with pain then expected to resolve after treatment directed at the source. Other sources can result in chronic intermittent pain that, for many, occurs on a weekly to daily basis, commonly attributed to gastroesophageal reflux, spasticity, and hip subluxation. Most challenging are pain sources attributable to the impaired central nervous system, requiring empirical medication trials directed at causes that cannot be identified by diagnostic tests, such as central neuropathic pain. Interventions reviewed include integrative therapies and medications, such as gabapentinoids, tricyclic antidepressants, α-agonists, and opioids. This clinical report aims to address, with evidence-based guidance, the inherent challenges with the goal to improve comfort throughout life in this vulnerable group of children.

Acute onset rhythmic hiccup-like respirations secondary to oral baclofen toxicity

OBJECTIVE

Baclofen toxicity has been associated with seizures, coma, apnea, autonomic disturbances, and cardiac conduction abnormalities. It has not been associated with rhythmic hiccup-like respirations.

METHOD

We report a patient with suspected baclofen toxicity.

RESULTS

Our patient is a 19-year-old girl with cerebral palsy secondary to prematurity and repaired tetralogy of Fallot who had started oral baclofen 8 months before to diminish spasticity. Her main concern was the acute onset of rhythmic, deep, continual, hiccup-like breaths every few seconds, increasing in frequency with exhaustion, and disappearing in sleep. The night after her evaluation, her symptoms significantly worsened. She presented at the Johns Hopkins pediatric emergency room where her symptoms were only somewhat responsive to a benzodiazepine; she was discharged without a clear etiology. After discussion the next day, her baclofen dose was reduced. Within 12 hours, her abnormal respirations disappeared without recurrence.

CONCLUSIONS

Respiration involves glutamatergic excitatory synaptic input to medullary inspiratory γ-aminobutyric acid-mediated pacemaker neurons. Baclofen acts on presynaptic γ-aminobutyric acid B receptors on glutamate axons; derangement of this system may explain the irregular respirations in our patient in a dose-dependent fashion.

Proconvulsant action of two GABA(B) receptor antagonists is age-dependent

Antagonists of GABA(B) receptors are expected to have proconvulsant action also in developing brain. Two antagonists (CGP55845 and CGP46381) were tested in a model of cortical epileptic afterdischarges (ADs) in 12-, 18- and 25-day-old rat pups with implanted electrodes. CGP55845 was dissolved in dimethylsulfoxide and the results demonstrated marked proconvulsant action of this solvent which masked possible action of the antagonist. Water soluble antagonist CGP46381 led to marked potentiation of ADs in 12-day-old animals, its action decreased with age, it was negligible in 25-day-old rats. Our results demonstrated important inhibitory role of GABA(B) receptors at very early stages of maturation.

Long-term oral baclofen treatment in a child with cerebral palsy: electroencephalographic changes and clinical adverse effects

Baclofen is widely used to control spasticity in children with cerebral palsy. Several publications described clinical adverse effects of baclofen oral treatment, but the effect of baclofen on seizure potentiation is still controversial. We describe a 10-year-old female patient with cerebral palsy, epilepsy, and mental retardation who developed clinical adverse effects (confusion, agitated state, insomnia, diffuse hypotonia, and hyporeflexia) and electroencephalographic (EEG) changes (quasiperiodic, generalized burst of sharp waves that take up >50% of standard EEG) during long-term oral baclofen treatment, after gradually increasing the dosage but still within the therapeutic dose. Our case showed clearly that the EEG changes in our patient, with a history of epilepsy in good control, have been induced by the baclofen increase, and we describe the possible mechanisms that could explain proconvulsive effect of baclofen.

Electroencephalographic abnormalities in baclofen-induced encephalopathy

We report a patient in whom the characteristic electroencephalographic features of baclofen intoxication are highlighted and emphasize the role of electrographic abnormalities in the diagnosis of this condition.

Common medical comorbidities associated with cerebral palsy

The medical issues associated with the diagnosis of cerebral palsy (CP) can have significant interplay with the neuromuscular issues that most physiatrists manage in the clinical setting. Identification and appropriate management of these common comorbidities by the primary care and subspecialist physicians can have significant impact on the quality of life of the patient and family. Some of these issues are prevalent across all gross motor function classification system (GMFCS) levels of severity, whereas others more commonly complicate the care of those children with the more severe GMFCS levels IV and V. Performance of a complete review of systems to address the potentially complex medical comorbidities and subsequent application of appropriate screening tools can assist in achieving optimal outcomes in children with CP and their families.

Nonoperative management of spasticity in children

Central to the longitudinal management of childhood hypertonia are nonsurgical treatments. These include physical and occupational therapy, electrical stimulation, orthotics, botulium toxin, and drugs. This manuscripts reviews these treatment modalities as well as evaluation tools available to assess their impact on a child's hypertonia.

Oral baclofen in children with cerebral palsy: a double-blind cross-over pilot study

AIM

To assess the effectiveness of oral baclofen in reducing spasticity and improving function in children with cerebral palsy.

METHODS

A double-blind, randomised cross-over pilot study of oral baclofen versus placebo. Assessment tools included the Goal Attainment Scale, Pediatric Evaluation of Disability Inventory, Modified Tardieu Scale and parent questionnaire.

RESULTS

Fifteen children with mean age 7.4 years (SD=2.7 years) and spastic or spastic/dystonic quadriplegia (Gross Motor Function Classification System Level IV or V) were enrolled. Children scored significantly better on the Goal Attainment Scale with baclofen compared with placebo (F(1,13)=4.5, P=0.05). There was no significant difference between baclofen and placebo for the Pediatric Evaluation of Disability Inventory or Modified Tardieu Scale. Parent questionnaire results are described.

CONCLUSION

This pilot study demonstrates that oral baclofen has an effect beyond placebo in improving goal-oriented tasks, such as transfers, in children with spastic quadriplegic cerebral palsy.

Ethanol blocks nicotine-induced seizures in mice: comparison with midazolam and baclofen

Low doses of ethanol may antagonize the pharmacological effects of nicotine. Recently, it has been shown that the effects of ethanol on nicotine discrimination are not correlated with blood ethanol levels. The aim of the present study was to evaluate whether ethanol (0.5-2g/kg, i.p.) could block nicotine-induced seizures in C57BL/6J mice and to correlate ethanol's actions with blood ethanol concentrations. For comparison, the effects of a gamma-aminobutyric acid A (GABAA)/benzodiazepine receptor positive modulator, midazolam (0.25-40 mg/kg, i.p.), and a gamma-aminobutyric acid B receptor agonist, baclofen (2.5-20 mg/kg, i.p.), were assessed in the same procedure. Nicotine (3-9 mg/kg, s.c.) induced clonic-tonic seizures in a dose-dependent manner. Ethanol, administered 5 or 50 min before nicotine, dose dependently antagonized seizures elicited by 6 mg/kg nicotine. The anticonvulsant effects of ethanol correlated with blood ethanol levels and were comparable to those exerted by midazolam. Baclofen antagonized only the tonic component of nicotine-induced convulsions. The anticonvulsant doses of ethanol (0.5-2 g/kg), midazolam (0.5-1 mg/kg), and baclofen (5-10 mg/kg) did not affect spontaneous locomotor activity in a control experiment. The present results indicate that (i) ethanol may block nicotine-induced seizures in mice at doses that do not alter locomotor activity and (ii) the anti-seizure effects of ethanol depend on blood ethanol levels and are comparable to those exerted by the GABAA positive modulator midazolam.

GABAB receptor antagonism abolishes the learning impairments in rats with chronic atypical absence seizures

Chronic atypical absence seizures are a component of the Lennox-Gastaut syndrome, a disorder invariably associated with severe cognitive impairment in children. However, the cause of this intellectual delay remains unclear. The AY9944 model of chronic atypical absence seizures in rats reliably reproduces the electrographic, behavioral, pharmacological and cognitive features of clinical atypical absence. Using this model, we tested the hypothesis that the cognitive impairment associated with this disorder involves a gamma-aminobutyric acid B (GABA(B)) receptor-mediated mechanism. Therefore, we examined the effect of a specific, high affinity GABA(B) receptor antagonist, CGP35348, on the atypical absence seizures, the working memory deficits, and the altered long-term potentiation that we have observed in the AY9944 model. CGP35348 blocked atypical absence seizures, restored long-term potentiation to normal level, and reversed the cognitive deficit in the AY9944-treated animals. However, dose-response studies showed that lower doses of CGP35348 that failed to influence atypical absence seizure activity, completely reversed the spatial working memory deficit. These data suggest that GABA(B) receptor-mediated mechanisms are responsible for the cognitive dysfunction in the AY9944 model of chronic atypical absence seizures and further, that their cognitive impairment is independent of the seizure activity. The data raise the possibility that GABA(B) receptor antagonists may have therapeutic potential for the treatment of cognitive impairment in epilepsy syndromes where atypical absence seizures are a component.

Tiagabine overdose: a case of status epilepticus in a non-epileptic patient

Tiagabine is an antiepileptic drug used as adjunctive therapy for partial seizures that is believed to selectively inhibit the presynaptic reuptake of gamma aminobutyric acid (GABA). We describe a case of a tiagabine overdose that resulted in status epilepticus (SE) in a patient with no seizure history. A 14-year-old girl with a history of asthma presented with convulsive SE after ingestion of an unknown amount of her sister's tiagabine in a suicide attempt. Attempted anticonvulsant therapy included a total of diazepam 10 mg IV, lorazepam 6 mg IV, pyridoxine 5 g IV, and fosphenytoin 20 mg PE/kg. All were without effect. A computed tomography and electrocardiogram were normal. Continuous bedside EEG monitoring showed suppression of seizure activity following intravenous midazolam. A tiagabine level obtained on ED arrival was 420 ng/mL (therapeutic 20-103 ng/mL). The patient was discharged to psychiatry within 1 week with no neurologic sequelae.

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.

Epilepsy and intrathecal baclofen therapy in children with cerebral palsy

The objective of this study was to analyze the relationship between epilepsy and intrathecal baclofen by investigating a consecutive sample of 150 children with cerebral palsy or spasticity of cerebral origin who underwent intrathecal baclofen. The medical charts of the 150 children were retrospectively reviewed. A series of 100 children with cerebral palsy, operated on other procedures, was reviewed as a control group. Forty percent of the 150 children had epilepsy before intrathecal baclofen pump implantation; 13.3% had a decrease in seizure frequency after intrathecal baclofen, while two children worsened and one child had seizures ex novo. We conclude that in children with spasticity of cerebral origin, intrathecal baclofen does not seem to aggravate or induce seizure activity.

Severe Seizures During Propofol Induction in a Patient with Syringomyelia Receiving Baclofen

We report the occurrence of recurrent severe generalized seizures during induction of anesthesia with propofol in a patient with syringomyelia receiving baclofen for flexor spasms undergoing neurosurgery. We discuss the possible epileptogenic interaction between baclofen and propofol in our patient.

The use of baclofen in full-term neonates with hypertonia

The use of baclofen in neonates has been minimally reported. We report on two term neonates who were treated successfully for hypertonia with baclofen.