Intrathecal baclofen withdrawal resembling serotonin syndrome in an adolescent boy with cerebral palsy

Catatonia and Neuroleptic Malignant Syndrome in Patients With Cerebral Palsy: Two Case Reports and a Systematic Review of the Literature

BACKGROUND

Patients with cerebral palsy, a group of movement disorders with motor, communication, and behavioral features that can mimic catatonic signs, could benefit from efforts to improve the detection and treatment of comorbid catatonia. Given that cerebral palsy frequently co-occurs with conditions associated with catatonia, such as autism spectrum disorder, epilepsy, intellectual disability, and mood and psychotic disorders, lifetime prevalence of catatonia in this population may be high.

OBJECTIVE

This study aimed to systematically review the literature on catatonia and the related condition of neuroleptic malignant syndrome (NMS) in patients with cerebral palsy while presenting 2 additional cases of catatonia.

METHODS

We used the terms "cerebral palsy" in combination with "catatoni∗," related terms for catatonia, and "neuroleptic malignant syndrome" to query Ovid MEDLINE (1948 to November 28, 2022), PsycINFO, Cumulative Index to Nursing, and Allied Health Literature, and Embase for applicable case reports. The Neuroleptic Malignant Syndrome Information Service database was also manually searched.

RESULTS

In addition to our 2 catatonia reports, we identified 10 reports of catatonia in patients with cerebral palsy, as well as 8 reports of NMS. Patients with both conditions responded well, and sometimes rapidly, to treatment. Notably, of the 5 patients with catatonia and cerebral palsy who received electroconvulsive therapy, 2 developed recurrent self-limited hyperthermia posttreatment. We also identified several cases of baclofen withdrawal, which can be life threatening because of seizure risk, presenting with NMS-like features in patients with cerebral palsy who had malfunctioning intrathecal baclofen pumps for spasticity management.

CONCLUSIONS

Given frequent comorbidity of conditions associated with catatonia in patients with cerebral palsy, as well as routine treatment with medications that can induce NMS, such as metoclopramide and anticholinergics, catatonia and NMS may be underreported in the cerebral palsy patient population, despite being highly treatable. Possible underdiagnosis of catatonia in patients with cerebral palsy may be because of misattribution of overlapping features between the 2 conditions to cerebral palsy. Clinicians should be aware of possible recurrent self-limited fever when using electroconvulsive therapy to treat patients with catatonia and cerebral palsy while also being vigilant for intrathecal baclofen withdrawal when encountering NMS-like features in patients with cerebral palsy.

Principles of Pharmacotherapy of Seizures and Status Epilepticus

Status epilepticus is a neurological emergency with an outcome that is highly associated with the initial pharmacotherapy management that must be administered in a timely fashion. Beyond first-line therapy of status epilepticus, treatment is not guided by robust evidence. Optimal pharmacotherapy selection for individual patients is essential in the management of seizures and status epilepticus with careful evaluation of pharmacokinetic and pharmacodynamic factors. With the addition of newer antiseizure agents to the market, understanding their role in the management of status epilepticus is critical. Etiology-guided therapy should be considered in certain patients with drug-induced seizures, alcohol withdrawal, or autoimmune encephalitis. Some patient populations warrant special consideration, such as pediatric, pregnant, elderly, and the critically ill. Seizure prophylaxis is indicated in select patients with acute neurological injury and should be limited to the acute postinjury period.

Intrathecal Baclofen Overdose With Paradoxical Autonomic Features Mimicking Withdrawal

BACKGROUND

Intrathecal Baclofen (ITB) has become an increasingly common treatment for severe muscle spasticity associated with conditions such as cerebral palsy and spinal cord injury. Classically, withdrawal symptoms mimic symptoms of serotonin syndrome with hypertension, increased spasticity, clonus, hyperthermia, tachycardia, and possibly acute psychosis. Hypotension, muscle flaccidity, and respiratory depression are generally considered symptoms of toxicity or overdose.

CASE REPORT

We present the case of a male with recent ITB pump revision who presented with autonomic features suggestive of Baclofen withdrawal, while the remainder of his physical examination suggested appropriate medication dosing. Interrogation of the patient's ITB pump revealed normal function, and the patient had no clinical change with intravenous benzodiazepines, but his condition ultimately improved when his Baclofen dosing was decreased, indicating toxicity instead of withdrawal. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: As Baclofen pump use increases, the importance of recognizing these potentially life-threatening complications also increases. This case presents the emergency physician with an atypical presentation and emphasizes the importance of a thorough neurologic examination to diagnose patients accurately.

Clinical Management of Dystonia in Childhood

Dystonia is one of the most frequent movement disorders in childhood. It can impede normal motor development and cause significant motor disability. The diagnostic evaluation of childhood dystonia is challenging due to the phenotypic variability and heterogeneous etiologies. Evidence to guide the diagnostic evaluation and treatment is limited. Assessment is primarily directed by clinical history and distinctive examination findings. Neuroimaging is typically necessary to evaluate for acquired or complex inherited dystonias. A trial of levodopa can be both diagnostic and therapeutic in children with dopa-responsive dystonia. However, for the majority of children with early-onset dystonia, treatment is symptomatic with varying efficacy. There is a paucity of therapeutic trials for childhood dystonia and most treatment recommendations are consensus or expert opinion driven. This review summarizes the available evidence and guidelines on the diagnostic evaluation and pharmacological treatment of childhood-onset dystonia and provides practical frameworks to approach both issues based on best evidence.

Baclofen Pumps: Uses and Complications

Intrathecal baclofen therapy, given via an implanted pump in the abdominal wall either as a continuous infusion or bolus dosing, has been used for more than 25 years to treat the spasticity and dystonia associated with various brain and spinal cord conditions. Pediatric clinicians occasionally encounter baclofen pumps, and in the pediatric setting, significant morbidity can arise from their use. This article presents the background, mechanism of action, uses, and complications of intrathecal baclofen therapy and discusses various management strategies should complications occur.

Baclofen in the Therapeutic of Sequele of Traumatic Brain Injury: Spasticity

Traumatic brain injury (TBI) is an alteration in brain function, caused by an external force, which may be a hit on the skull, rapid acceleration or deceleration, penetration of an object, or shock waves from an explosion. Traumatic brain injury is a major cause of morbidity and mortality worldwide, with a high prevalence rate in pediatric patients, in which treatment options are still limited, not available at present neuroprotective drugs. Although the therapeutic management of these patients is varied and dependent on the severity of the injury, general techniques of drug types are handled, as well as physical and surgical. Baclofen is a muscle relaxant used to treat spasticity and improve mobility in patients with spinal cord injuries, relieving pain and muscle stiffness. Pharmacological support with baclofen is contradictory, because disruption of its oral administration may cause increased muscle tone syndrome and muscle spasm, prolonged seizures, hyperthermia, dysesthesia, hallucinations, or even multisystem organ failure. Combined treatments must consider the pathophysiology of broader alterations than only excitation/inhibition context, allowing the patient's reintegration with the greatest functionality.

A Randomized Dose Escalation Study of Intravenous Baclofen in Healthy Volunteers: Clinical Tolerance and Pharmacokinetics

BACKGROUND

Abrupt discontinuation of baclofen can result in a potentially severe withdrawal syndrome. The current treatment for baclofen withdrawal is inadequate, resulting in a critical need to develop an alternative method to prevent or treat this withdrawal syndrome.

OBJECTIVE

To evaluate the safety profile and pharmacokinetics of oral (PO) and investigational intravenous (IV) baclofen formulations at clinically relevant doses.

DESIGN

Randomized, open-label, dose-escalation, crossover study.

SETTING

Contract Research Organization (CRO).

METHODS

Three cohorts of 12 healthy adults received single doses of PO baclofen (10 mg, 15 mg or 20 mg) and 10-minute infusions of IV baclofen (7.5 mg, 11.5 mg, or 15 mg) with a minimum 48-hour wash-out period. The third cohort also received a 60-minute infusion of 15 mg IV baclofen after an additional 48-hour wash-out period.

MAIN OUTCOME MEASURES

Subjects were observed in a CRO for 24 hours after each dose of baclofen, and were assessed for nystagmus, ataxia, and sedation. Blood samples were collected from 0 to 24 hours and analyzed for baclofen concentration using high-performance liquid chromatography-mass spectroscopy. Noncompartmental pharmacokinetic analyses were performed. Dose linearity and proportionality was assessed using 2-way repeated-measures analysis of variance and a power model analysis.

RESULTS

None of the PO or IV doses resulted in significant sedation compared to baseline. All subjects could perform tandem gait after each baclofen dose. The most common side effect, transient mild nystagmus, was noted in 4 of 36 and in 13 of 36 subjects after PO and IV administration, respectively. This was likely related to increased maximum concentrations (C_max). After the 20 mg PO and 15 mg IV doses, mean C_max levels were 255 and 722 ng/mL and half-lives were 5.24 and 5.79 hours for PO and IV baclofen, respectively. The mean oral bioavailability for the 20-mg PO dose was approximately 80%.

CONCLUSIONS

All PO and IV doses of baclofen were well tolerated clinically. The 80% bioavailability suggests that a 20% reduction in IV dose will produce comparable total drug exposures to that of the PO dose. When PO therapy is interrupted, bridging with IV baclofen may be feasible.

LEVEL OF EVIDENCE

II.

Baclofen pump catheter leakage after migration of the abdominal catheter in a pediatric patient with spasticity

The authors report an unusual case of intrathecal baclofen withdrawal due to the perforation and subsequent leakage of a baclofen pump catheter in a patient with spastic cerebral palsy. A 15-year-old boy underwent an uncomplicated placement of an intrathecal baclofen pump for the treatment of spasticity due to cerebral palsy. After excellent control of symptoms for 3 years, the patient presented to the emergency department with increasing tremors following a refill of his baclofen pump. Initial evaluation consisted of radiographs of the pump and catheter, which appeared normal, and a successful aspiration of CSF from the pump's side port. A CT dye study revealed a portion of the catheter directly overlying the refill port and extravasation of radiopaque dye into the subfascial pocket anterior to the pump. During subsequent revision surgery, a small puncture hole in the catheter was seen to be leaking the drug. The likely cause of the puncture was an inadvertent perforation of the catheter by a needle during the refilling of the pump. This case report highlights a unique complication in a patient with an intrathecal baclofen pump. Physicians caring for these patients should be aware of this rare yet potential complication in patients presenting with baclofen withdrawal symptoms.

A pilot study assessing pharmacokinetics and tolerability of oral and intravenous baclofen in healthy adult volunteers

Our objective was to characterize baclofen pharmacokinetics and safety given orally and intravenously. Twelve healthy subjects were enrolled in a randomized, open-label, crossover study and received single doses of baclofen: 3 or 5 mg given intravenously and 5 or 10 mg taken orally with a 48-hour washout. Blood samples for baclofen analysis were collected pre-dose and at regular intervals up to 24 hours post-dose. Clinical response was assessed by sedation scores, ataxia, and nystagmus. Mean absolute bioavailability of oral baclofen was 74%. Dose-adjusted areas under the curve between the oral and intravenous arms were statistically different (P = .0024), whereas area under the curve variability was similar (coefficient of variation: 18%-24%). Adverse effects were mild in severity and not related to either dose or route of administration. Three- and 5-mg intravenous doses of baclofen were well tolerated. Seventy-four percent oral bioavailability indicates that smaller doses of intravenous baclofen are needed to attain comparable total drug exposures.

Cardiac arrest due to baclofen withdrawal syndrome

A 41-year-old man presented with postcervical traumatic complete quadriparesis under intrathecal baclofen therapy (ITB) for refractory spasticity. Less than 24 h after having his baclofen pump substituted, he develops hyperthermia, seizures, cognitive depression, acute hypoxaemic respiratory failure and cardiovascular instability leading to mechanical ventilation and vasopressor support. He was transferred to an intensive care unit with diagnosis of community-acquired pneumonia leading to septic shock. He evolved with progressive clinical worsening and multisystem organ failure and cardiac arrest in non-shockable rhythm (pulseless electrical activity)--4 min resuscitation with return of spontaneous circulation. Considering the possible diagnosis of baclofen withdrawal syndrome and, in suspicion of ITB delivery disruption, the catheter system was surgically explored and a leaking tubule attachment was found. Despite aggressive cardiovascular, respiratory and renal support therapy, clinical improvement occurred only after restoration of intrathecal drug delivery. He was discharged from the hospital after 56 days, having returned to baseline status.

Baclofen withdrawal presenting as irritability in a developmentally delayed child

Irritability in children has a broad differential diagnosis, ranging from benign processes to life-threatening emergencies. In children with comorbid conditions and developmental delay, the diagnostic process becomes more challenging. This case report describes a developmentally delayed 14-year-old boy who presented with pain and crying caused by a malfunction of a surgically implanted baclofen pump. We describe recommendations concerning the diagnostic evaluation, medical management, and surgical repair.

Polyanalgesic Consensus Conference 2012: recommendations for the management of pain by intrathecal (intraspinal) drug delivery: report of an interdisciplinary expert panel

INTRODUCTION

The use of intrathecal (IT) infusion of analgesic medications to treat patients with chronic refractory pain has increased since its inception in the 1980s, and the need for clinical research in IT therapy is ongoing. The Polyanalgesic Consensus Conference (PACC) panel of experts convened in 2000, 2003, and 2007 to make recommendations on the rational use of IT analgesics based on preclinical and clinical literature and clinical experiences.

METHODS

The PACC panel convened again in 2011 to update the standard of care for IT therapies to reflect current knowledge gleaned from literature and clinical experience. A thorough literature search was performed, and information from this search was provided to panel members. Analysis of published literature was coupled with the clinical experience of panel members to form recommendations regarding the use of IT analgesics to treat chronic pain.

RESULTS

After a review of literature published from 2007 to 2011 and discussions of clinical experience, the panel created updated algorithms for the rational use of IT medications for the treatment of neuropathic pain and nociceptive pain.

CONCLUSIONS

The advent of new algorithmic tracks for neuropathic and nociceptive pain is an important step in improving patient care. The panel encourages continued research and development, including the development of new drugs, devices, and safety recommendations to improve the care of patients with chronic pain.

Acute intrathecal baclofen withdrawal: a brief review of treatment options

BACKGROUND

Acute baclofen toxicity and withdrawal can present with a constellation of symptoms making differentiation between these two entities and other potential diagnoses challenging. Baclofen withdrawal is associated with numerous complications which may require neurocritical care expertise such as respiratory failure, refractory seizures, delirium, and blood pressure lability.

METHODS

Case report and literature review.

RESULTS

This case report discusses a case of intrathecal baclofen (ITB) withdrawal, focusing on the differential diagnosis for acute baclofen withdrawal and reviews the various options that exist to treat the symptoms of acute baclofen withdrawal such as benzodiazepines, propofol, skeletal muscle relaxants, and tizanidine.

CONCLUSIONS

Critical care practitioners should be prepared to treat this potentially devastating and often refractory complication of ITB therapy.

Status dystonicus resembling the intrathecal baclofen withdrawal syndrome: a case report and review of the literature

Introduction

Status dystonicus is a rare but life-threatening disorder characterized by increasingly frequent and severe episodes of generalized dystonia that may occur in patients with primary or secondary dystonia. Painful and repetitive spasms interfere with respiration and may cause metabolic disturbances such as hyperpyrexia, dehydration, respiratory insufficiency, and acute renal failure secondary to rhabdomyolysis. Intrathecally administered baclofen, delivered by an implantable pump system, is widely used for the treatment of refractory spasticity. Abrupt cessation of intrathecal baclofen infusion has been associated with a severe withdrawal syndrome comprised of dystonia, autonomic dysfunction, hyperthermia, end-organ failure and sometimes death. The aetiology of this syndrome is not well understood. Status dystonicus describes the episodes of acute and life-threatening generalized dystonia, which occasionally manifest themselves in patients with dystonic syndromes.

Case presentation

We present the case of a nine-year-old Caucasian boy who experienced a severe episode of status dystonicus with no known cause and clinical features resembling those described in intrathecal baclofen withdrawal. Our patient subsequently underwent the placement of an intrathecal baclofen pump without incident.

Conclusion

The similarity between the clinical features of the case we present and those reported in connection to abrupt withdrawal of intrathecal baclofen is emphasized. Several drugs, although not intrathecal baclofen withdrawal, have previously been associated with status dystonicus. The similarity between the life-threatening dystonic episode experienced by our patient, and those reported in intrathecal baclofen withdrawal, highlights the possibility that, rather than representing a true physiological withdrawal syndrome, abrupt withdrawal of intrathecal baclofen may simply precipitate an episode of status dystonicus in susceptible individuals. The clinical similarities between the intrathecal baclofen withdrawal syndrome and status dystonicus have not previously been highlighted.

Intrathecal administration of GABA agonists in the vegetative state

Gamma aminobutyric acid (GABA) is an inhibitor neurotransmitter that plays many important roles in the central nervous system. Because the half-life time of GABA is very short in vivo, GABA itself is not used for clinical practice. An analogue of GABA, baclofen, is an agonist of GABA-B receptor, and has very strong antispastic effect by acting to the posterior horn of the spinal cord. However, baclofen poorly crosses through the blood brain barrier, and the antispastic effect is modest when administered orally. Therefore, direct continuous infusion of small doses of baclofen into the cerebrospinal fluid (intrathecal baclofen therapy, ITB) has become an established treatment for control of otherwise intractable severe spasticity. Spasticity is clinically defined as hypertonic state of the muscles with increased tendon reflexes, muscles spasm, spasm pain, abnormal posture, and limitation of involuntary movements. Spasticity is a common symptom after damage mainly to the pyramidal tract system in the brain or the spinal cord. Such damage is caused by traumatic brain injury, stroke, spinal cord injury, multiple sclerosis, and so on. Patients in persistent vegetative state (PVS) usually have diffuse and widespread damage to the brain, spasticity is generally seen in such patients. Control of spasticity may become important in the management of PVS patients in terms of nursing care, pain relief, and hygiene, and ITB may be indicated. Among PVS patients who had ITB to control spasticity, sporadic cases of dramatic recovery from PVS after ITB have been reported worldwide. The mechanism of such recovery of consciousness is poorly understood, and it may simply be a coincidence. On the other hand, electrical spinal cord stimulation (SCS) has been tried for many years in many patients in PVS, and some positive effects on recovery of consciousness have been reported. SCS is usually indicated for control of neuropathic pain, but it has also antispastic effect. The mechanism of SCS on pain is known to be mediated through the spinal GABA neuronal system. Thus, ITB and SCS have a common background, spinal GABA neuronal mechanism. The effect of GABA agonists on recovery of consciousness is not yet established, but review of such case studies becomes a clue to solve problems in PVS, and there may be hidden serendipity.