Case report: Intrathecal baclofen therapy improved gait pattern in a stroke patient with spastic dystonia

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Case report: Intrathecal baclofen therapy improved gait pattern in a stroke patient with spastic dystonia

Kyung Min Kim¹ Tae Kwon Lee¹ Su Min Lee¹ Won Seok Chang² Su Ji Lee¹ Jihye Hwang^{1 ,3 *} Sung-Rae Cho^{1 ,3 ,4 ,5 *}

• ¹Department and Research Institute of Rehabilitation Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea
• ²Department of Neurosurgery and Brain Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
• ³Graduate Program of Biomedical Engineering, Yonsei University College of Medicine, Seoul, Republic of Korea
• ⁴Brain Korea 21 FOUR Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
• ⁵Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Republic of Korea

Background: Intrathecal baclofen (ITB) therapy, a viable alternative for unsuitable candidates of conventional spasticity medications, is a preferred method of administration over the oral route. Owing to its enhanced bioavailability, ITB ensures a more effective delivery at the target site.

Objective: There is a lack of conclusive evidence regarding the use of ITB treatment in managing ambulatory patients with spastic dystonia. Before ITB pump implantation, patients commonly undergo an ITB bolus injection trial to rule out potential adverse reactions and verify the therapeutic effects on hypertonic issues. In this report, we highlight a case of spastic dystonia, particularly focusing on an ambulatory patient who demonstrated significant improvement in both the modified Ashworth scale (MAS) score and gait pattern following the ITB injection trial.

Case report: This case report outlines the medical history of a 67-year-old male diagnosed with left-side hemiplegia and spastic dystonia, resulting from his second episode of intracranial hemorrhage in the right thalamus. An ITB injection trial was initiated because the patient was not suitable for continued botulinum toxin injections and oral medications. This was due to the persistent occurrence of spastic dystonia in both the upper and lower extremities. The patient underwent a four-day ITB injection trial with progressively increasing doses, resulting in improved MAS scores and gait parameters, including cadence, step length, step time, stride length, and stride time were increased. Particularly, kinematic gait analysis demonstrates a substantial improvement of increased knee flexion in the swing phase in stiff knee gait pattern. These findings indicated a gradual reduction in spasticity-related symptoms, signifying the positive effect of the ITB injection trial. The patient eventually received an ITB pump implantation.

Conclusion: In this post-stroke patient with spastic dystonia, ITB therapy has demonstrated effective and substantial management of spasticity, along with improvement in gait patterns.

Introduction

Spasticity is defined as velocity-dependent hypertonia and tendon jerk hyperreflexia, resulting from stretch reflex excitability (1, 2). In contrast, dystonia involves involuntary muscle contractions, often leading to abnormal posturing and twisting movements (3). There are different types of dystonia, including focal dystonia such as blepharospasm, oromandibular dystonia, spasmodic dysphonia, torticollis, and writer’s cramp (4, 5). Generalized dystonia involves the leg, trunk, and at least one other body part (6). Spastic dystonia, which is a specific aspect of the upper motor neuron syndrome, is characterized by involuntary tonic contractions caused by the inability to relax the muscles (1). Spastic overactivity, a prevalent subtype of muscle hypertonia is frequently observed in patients with spinal or cerebral dysfunction. The term “spastic overactivity,” frequently employed to describe stretch-sensitive muscle overactivity, poses difficulties in precisely defining this intricate condition, as it includes spasms, involuntary motions, and undesired muscle activity (7).

The primary treatment for muscle overactivity and generalized dystonia typically involves oral medications, including baclofen, benzodiazepines, anticholinergics, antispasmodics, and levodopa (8, 9). Baclofen, an agonist for gamma-aminobutyric acid (GABA) B receptors, inhibits mono- and polysynaptic reflexes in the central and peripheral nervous systems, contributing to its therapeutic effect in reducing spasticity (10). Previous research explored the effectiveness of oral baclofen in managing poststroke spasticity, focusing on ankle stiffness and clonus during passive stretch, and identified factors influencing responsiveness (2). Nevertheless, oral baclofen may not always be effective for all patients due to the low concentration of baclofen in the cerebrospinal fluid (2). These non-responders exhibited a positive effect at higher cerebrospinal fluid levels achievable through intrathecal baclofen injection (2). Benzodiazepines demonstrate limited effectiveness, with approximately 16 to 23% showing a good clinical response (11). Trihexyphenidyl, a widely used agent, is a muscarinic acetylcholine receptor antagonist with a notably variable therapeutic dosage. While children may effectively respond to doses as low as 4 mg/day, adults are less likely to tolerate increasing dosages when necessary as they tend to be more sensitive to side effects such as memory loss, confusion, restlessness, insomnia, and nightmares (11). Intramuscular botulinum toxin injections can be beneficial in reducing focal spasticity in specific muscle groups (12, 13). Adverse effects, including dry mouth, fatigue, and flu-like symptoms, may occur when the drug spreads to unintended muscles and organs during botulinum toxin therapy (13). In some cases, these manifestations can escalate to systemic botulism signs. Although recent studies support the safety of botulinum toxin high-dose therapy, official documents recommend maximum botulinum toxin doses of onabotulinumtoxinA (Botox®, Allergan, Irvine, CA, USA) 400 units for upper limb or lower limb spasticity (14, 15). In the 1980s, intrathecal baclofen (ITB) therapy emerged as potentially effective next-in-line management for severe spasticity unresponsive to oral medications (9, 16–18), delivering concentrated drug doses directly into the intrathecal space to minimize systemic toxicity (19). Given the delicate nature of baclofen therapy and its potential complications, ITB bolus injections are administered to rule out adverse reactions and ensure the drug’s therapeutic effect on hypertonia before ITB pump implantation (9). ITB therapy offers reversible treatment of spasticity and effective modulation of muscle tone to reduce severe spasticity, for it was approved for the management of spasticity (20, 21). However, current literature highlights the necessity for additional research on the effectiveness of ITB treatment for mixed hypertonia, including spastic dystonia (21). In particular, additional research dedicated to ambulatory patient is essential.

Evaluating the effectiveness of treatment is crucial in managing spastic overactivity, and commonly employed methods include high-speed passive muscle stretching assessments like the modified Ashworth scale (MAS) and the modified Tardieu scale. However, these evaluations solely gauge resistance to passive movement and lack insight into muscle dynamics during dynamic tasks like gait (22). These scales also rely on subjective interpretation by clinicians, making it challenging to differentiate specific types of spastic hyperactivity, such as spasticity, spastic dystonia, and spastic co-contraction. Therefore, surface electromyography or gait analysis reflecting muscle activity during dynamic tasks has recently been used to classify spastic overactivity in detail (23, 24). Gait analysis, in particular, assesses muscle hyperactivity during functional tasks, allowing for a comprehensive understanding of specific movement patterns and continuous monitoring of various gait factors (23). Moreover, a transient decrease in spastic dystonia following ITB therapy can induce changes in gait pattern that are not easily discernible through casual observation. In such cases, gait analysis offers precise and objective measurements, detecting even subtle modifications in ambulatory performance (25).

Herein, we report an ambulatory patient with spastic dystonia demonstrating significant improvement in both the MAS score and gait pattern following the ITB bolus injection trial. The objective of this case study is to enhance comprehension of the response of adult spastic dystonia patients to ITB bolus injections and identify prospective recipients who may experience improved gait after ITB pump implantation. This study also represents the first stage in assessing whether the walking performance observed during the ITB bolus injection trial, evaluated through computerized gait analysis, is associated with changes following ITB pump implantation.

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