Intrathecal Baclofen Dosing Regimens: A Retrospective Chart Review

Characteristics of Changes in Intrathecal Baclofen Dosage over Time due to Causative Disease

Intrathecal baclofen (ITB) therapy effectively treats spasticity caused by brain or spinal cord lesions. However, only a few studies compare the course of treatment for different diseases. We investigated the change in daily dose of baclofen per year and its associated adverse events in patients presenting with the three most common etiologies at our institute: hereditary spastic paraplegia, cerebral palsy, and spinal cord injury. The ITB pumps were implanted from July 2007 to August 2019, with a mean follow-up period of 70 months. In patients with hereditary spastic paraplegia, baclofen dosage was reduced after eight years following ITB introduction, and the treatment was terminated in one patient owing to disease progression. In patients with cerebral palsy, the dosage increased gradually, and became constant in the 11th year. Patients with spinal cord injury gradually increased their baclofen dosage throughout the entire observation period. Severity and adverse event rates were higher in patients with cerebral palsy than in others. The degree and progression of spasticity varied depending on the causative disease. Understanding the characteristics and natural history of each disease is important when continuing ITB treatment.

Intrathecal and Oral Baclofen Use in Adults With Spinal Cord Injury: A Systematic Review of Efficacy in Spasticity Reduction, Functional Changes, Dosing, and Adverse Events

OBJECTIVE

To examine the efficacy, dosing, and safety profiles of intrathecal and oral baclofen in treating spasticity after spinal cord injury (SCI).

DATA SOURCES

PubMed and Cochrane Databases were searched from 1970-2018 with keywords baclofen, spinal cord injury, and efficacy.

STUDY SELECTION

The database search yielded 588 sources and 10 additional relevant publications. After removal of duplicates, 398 publications were screened.

DATA EXTRACTION

Data were extracted using the following population, intervention, comparator, outcomes, and study designs criteria: studies including adult patients with SCI with spasticity; the intervention could be oral or intrathecal administration of baclofen; selection was inclusive for control groups, surgical management, rehabilitation, and alternative pharmaceutical agents; outcomes were efficacy, dosing, and adverse events. Randomized controlled trials, observational studies, and case reports were included. Meta-analyses and systematic reviews were excluded.

DATA SYNTHESIS

A total of 98 studies were included with 1943 patients. Only 4 randomized, double-blinded, and placebo-controlled trials were reported. Thirty-nine studies examined changes in the Modified Ashworth Scale (MAS; 34 studies) and Penn Spasm scores (Penn Spasm Frequency; 19 studies), with average reductions of 1.7±1.3 and 1.6±1.4 in individuals with SCI, respectively. Of these data, a total of 6 of the 34 studies (MAS) and 2 of the 19 studies (Penn Spasm Frequency) analyzed oral baclofen. Forty-three studies addressed adverse events with muscle weakness and fatigue frequently reported.

CONCLUSIONS

Baclofen is the most commonly-prescribed antispasmodic after SCI. Surprisingly, there remains a significant lack of large, placebo-controlled, double-blinded clinical trials, with most efficacy data arising from small studies examining treatment across different etiologies. In the studies reviewed, baclofen effectively improved spasticity outcome measures, with increased efficacy through intrathecal administration. Few studies assessed how reduced neural excitability affected residual motor function and activities of daily living. A host of adverse events were reported that may negatively affect quality of life. Comparative randomized controlled trials of baclofen and alternative treatments are warranted because these have demonstrated promise in relieving spasticity with reduced adverse events and without negatively affecting residual motor function.

Does the Addition of Intrathecal Baclofen Along with or After Soft-Tissue Hip Adductor Surgery Decrease the Need for Hip Reconstruction Compared with Soft-Tissue Surgery Alone for Children with Nonambulatory Cerebral Palsy?

Purpose

Intrathecal baclofen (ITB) is a well-known treatment option for cerebral palsy (CP) spasticity. The combination of soft-tissue release and ITB for spasticity is common. This study compared patients who had soft-tissue release before ITB (PRE-ITB), soft-tissue release at the same time as ITB (ST-ITB), and no ITB (NON-ITB) but had soft-tissue release at a similar age as PRE-ITB.

Methods

Inclusion criteria were a spastic or mixed nonambulatory CP diagnosis, prior hip adductor surgery, no prior reconstructive surgery, and at least a five-year post-operative follow-up. Thirty hips were identified as PRE-ITB, 20 hips as ST-ITB, and 43 hips as NON-ITB. The primary outcome variables were the subsequent hip surgery during the study period and/or a migration percentage ≥ 50% at the final follow-up defined as "unsuccessful hip."

Results

The mean follow-up duration was 9.0 years (SD 2.4) for PRE-ITB, 9.4 (SD 3.6) for ST-ITB, and 9.3 (SD 3) for NON-ITB. The odds of unsuccessful outcomes were not different between NON-ITB and PRE-ITB but were lower for the ST-ITB group. The need for subsequent osteotomies or revision adductor surgery was significantly higher in ST-ITB compared with PRE-ITB (p = 0.02) or NON-ITB (p = 0.015). The incidence of surgical site infection over the whole follow-up period was higher in ST-ITB (40%) compared with PRE-ITB (13.3%, p = 0.035) and NON-ITB (0, p < 0.001).

Conclusion

The addition of tone management with ITB did not reduce the need for later hip surgery but did increase the risk for surgical site infection.

Management of severe spasticity with and without dystonia with intrathecal baclofen in the pediatric population: a cross-sectional study

Objective

To investigate the differences in delivery mode, daily dose, and catheter tip location in pediatric patients using intrathecal baclofen (ITB) pumps with spasticity plus dystonia versus spasticity alone.

Methods

A single-center, cross-sectional study was performed by collecting retrospective data from electronic medical records. Demographic and diagnostic information was obtained, comparing patients with spasticity with or without dystonia. The data were analyzed for group differences using a two-tailed Student’s t-test. Categorical data were analyzed for group differences using Pearson’s χ2 test.

Results

A total of 137 patients met the criteria. The majority (114) had spasticity plus dystonia whereas only 23 were documented as spasticity alone. Simple continuous dosing was the most common delivery mode, but flex dosing was used more than twice as frequently with spasticity plus dystonia compared with spasticity alone (42% vs 17%). Patients with spasticity plus dystonia also had more rostral catheter tip locations.

Conclusions

While it has been discussed anecdotally, this study confirms the supposition that patients with spasticity plus dystonia have increased dose requirements when compared with those with spasticity alone. Although there are no clear standards of care when managing these patients, they are often on higher daily dosages, are more likely to require flexed dosing method, and have higher catheter placements. Still, there are few studies that demonstrate improvements in dystonia with the use of ITB. In general, these patients would benefit from the development of universal standardizations as well as the confirmation that this is an appropriate treatment.

Dosing Patterns In Treatment of Disabling Spasticity With Intrathecal Baclofen

PURPOSE

The aim of this study was to describe and analyze dosing patterns for patients with ITB treatment over time and to identify possible subgroups demonstrating diversity in patterns.

DESIGN

A retrospective design.

METHODS

For 81 patients from six different hospitals, baclofen doses from the first 2 years of treatment were identified using medical records. Line graphs of each patient's doses were analyzed and grouped based on similarities in dosing pattern.

FINDINGS

The analyses of the dosing patterns resulted in four different subgroups classified as stable, slow increase, rapid increase, and fluctuating.

CONCLUSION

The results highlight the clinical challenge of predicting dose development over time.

CLINICAL RELEVANCE TO REHABILITATION NURSING

This study provides rehabilitation healthcare professionals with a better understanding of intrathecal baclofen dose development. Illustrations of the four subgroups can be used as an educational tool for patients, family, and caregivers.

Intrathecal Therapies

Intrathecal baclofen therapy is a well-established technique for spasticity management. This article briefly reviews the pharmacology of intrathecal baclofen as well as customary approach for utilization of this targeted drug delivery concept. Following these descriptions, four unusual presentations will be described, including the need for initial trialing, patient-directed boluses during chronic intrathecal baclofen therapy, use of medications other than baclofen for intrathecal therapy in spastic patients, and intraventricular baclofen delivery. These hypothetical cases are provided in an effort to expand the use of targeted drug delivery to larger population of spastic patients.

Analgesic effect of ADX71441, a positive allosteric modulator (PAM) of GABAB receptor in a rat model of bladder pain

Therapeutic use of GABA_B receptor agonists for conditions like chronic abdominal pain, overactive bladder (OAB) and gastroesophageal reflux disease (GERD) is severely affected by poor blood-brain barrier permeability and potential side effects. ADX71441 is a novel positive allosteric modulator (PAM) of the GABA_B receptor that has shown encouraging results in pre-clinical models of anxiety, pain, OAB and alcohol addiction. The present study investigates the analgesic effect of ADX71441 to noxious stimulation of the urinary bladder and colon in rats. In female Sprague-Dawley rats, systemic (i.p), but not intrathecal (i.t), administration of ADX71441 produced a dose-dependent decrease in viscero-motor response (VMR) to graded urinary bladder distension (UBD) and colorectal distension (CRD). Additionally, intra-cerebroventricular (i.c.v.) administration of ADX71441 significantly decreased the VMRs to noxious UBD. In electrophysiology experiments, the drug did not attenuate the responses of UBD-sensitive pelvic nerve afferent (PNA) fibers to UBD. In contrast, ADX71441 significantly decreased the responses of UBD-responsive lumbosacral (LS) spinal neurons in spinal intact rats. However, ADX71441 did not attenuate these LS neurons in cervical (C1-C2) spinal transected rats. During cystometrogram (CMG) recordings, ADX71441 (i.p.) significantly decreased the VMR to slow infusion without affecting the number of voiding contraction. These results indicate that ADX71441 modulate bladder nociception via its effect at the supra-spinal sites without affecting the normal bladder motility and micturition reflex in naïve adult rats.

Spinal Cord Stimulation for Spasticity: Historical Approaches, Current Status, and Future Directions

INTRODUCTION

Millions of people worldwide suffer with spasticity related to irreversible damage to the brain or spinal cord. Typical antecedent events include stroke, traumatic brain injury, and spinal cord injury, although insidious onset is also common. Regardless of the cause, the resulting spasticity leads to years of disability and reduced quality of life. Many treatments are available to manage spasticity; yet each is fraught with drawbacks including incomplete response, high cost, limited duration, dose-limiting side effects, and periodic maintenance. Spinal cord stimulation (SCS), a once promising therapy for spasticity, has largely been relegated to permanent experimental status.

METHODS

In this review, our goal is to document and critique the history and assess the development of SCS as a treatment of lower limb spasticity. By incorporating recent discoveries with the insights gained from the early pioneers in this field, we intend to lay the groundwork needed to propose testable hypotheses for future studies.

RESULTS

SCS has been tested in over 25 different conditions since a potentially beneficial effect was first reported in 1973. However, the lack of a fully formed understanding of the pathophysiology of spasticity, archaic study methodology, and the early technological limitations of implantable hardware limit the validity of many studies. SCS offers a measure of control for spasticity that cannot be duplicated with other interventions.

CONCLUSIONS

With improved energy-source miniaturization, tailored control algorithms, novel implant design, and a clearer picture of the pathophysiology of spasticity, we are poised to reintroduce and test SCS in this population.

Baclofen Solution for Low-Volume Therapeutic Delivery

OBJECTIVES

Baclofen is a zwitterion molecule where increased ions in the excipient increase the solubility. We developed baclofen in a stable solution similar to cerebrospinal fluid (CSF) without bicarbonate and proteins to improve the solubility of the baclofen and to reduce the potential toxicity to the central nervous system (CNS) and subarachnoid space. The objective is to develop a solution of baclofen wherein baclofen is solubilized in a multivalent physiological ion solution such as artificial cerebrospinal fluid (aCSF) at a concentration from 2 mg/cc to 10 mg/cc.

METHODS

First, to determine the solubility of Baclofen in aCSF, solubility was determined at six different pH levels at 37°C, by the addition of aCSF to a known amount of Baclofen. The final concentrations were confirmed by high performance liquid chromatography (HPLC) analysis. Second, the stability of Baclofen at 4 mg/cc investigated in a test manufacturing batch utilizing standard methods of production of 1500 20 cc vials inverted for 18 months at 25°C at 60% humidity. The stability and purity of the baclofen was verified at 18 months by HPLC analysis.

RESULTS

Baclofen was initially soluble between pH of 6-8 above 7 mg/cc but fell back to 6.3-5.8 mg/cc level with time. Baclofen produced in vials with inversion were noted to be stable at 4 mg/cc at 18 months with less than 2% breakdown of the baclofen in solution.

CONCLUSION

Baclofen is much more soluble in artificial CSF than normal saline. The artificial CSF may also be less toxic to the subarachnoid space than saline.

Pharmacologic management of non-neurogenic functional obstruction in women

INTRODUCTION

Impaired bladder emptying in women without neurologic disease may be related to urethral obstruction and/or impaired bladder contractility. Mechanical obstruction generally requires surgical management and options are limited for impaired bladder contractility. However, functional obstruction from voiding dysfunction or primary bladder neck obstruction may present an opportunity for pharmacologic intervention.

AREAS COVERED

In this review, the authors extensively reviewed available literature regarding the use of off-label medications for functional bladder outlet obstruction in women. In addition, side effect profiles and pharmacology of these medications determined from on-label indications are reviewed. Specific medications reviewed include vaginal diazepam, baclofen, urethral botulinum toxin injection, and alpha-adrenergic blockers.

EXPERT OPINION

Alpha-blockers in particular have demonstrated promise in women with demonstrable or suspected bladder outlet obstruction with side effect profiles similar to those observed in men. However, lack of quality data hinders informed decision making with alpha-blockers or any of the other agents studied in women with non-neurogenic functional outlet obstruction. In the absence of well-designed, placebo-controlled multi-institutional trials, those prescribing these medications must be aware of special considerations and side effects associated with relatively unfamiliar treatments in the context of uncertain benefit.