Reprinted from Manitoba Medicine, Vol. 63, No. 3, 1993, pp. 90-91...

Intrathecal baclofen for control of spasticity in patients with traumatic or inflammatory myelopathy

Patricia Nance¹ MD FRCPC, Brian Schmidt² MD FRCPC, Derek Fewer³ MD FRCPC

Department of Medicine^1,2, Section of Physical Medicine and Rehabilitation¹, Section of Neurology², Department of Surgery, Section of Neurosurgery³, University of Manitoba

One of the main inhibitory transmitters in the central nervous system is gamma aminobutyric acid (GABA). Baclofen is a GABAb receptor agonist, resistant to reversal by bicuculline, which has been used for the treatment of spasticity due to neurological dysfunction since 1966. Even though baclofen does cross the blood-brain barrier after oral administration, when given intrathecally baclofen has a much greater effect and at approximately 1/100th of the oral dose. Intrathecal baclofen for the treatment of spasticity has been reported in the United States and Europe.^1-4 However, the results of further studies are needed before this treatment can be made available for general clinical use in Canada. We initiated a prospective trial of intrathecal baclofen therapy for adults with spasticity due to spinal cord injury or multiple sclerosis at the Spinal Cord Injury Unit of the Health Sciences Centre, University of Manitoba in 1990.

Figure 1 Ashworth score for each subject before intrathecal baclofen treatment (open bars) compared with scores after treatment (hatched bars)

Patients and Study Method

A specialized clinic was established for the assessment and treatment of spasticity. Over the past two years, we have interviewed and examined 84 patients with spasticity due to spinal cord injury (n=66) or multiple sclerosis (n=18). There were 19 females and 65 males, ranging in age from 17 to 62 years. Spasticity `severity' was measured in two ways: by using a clinical scale of leg tone, the Ashworth scale; and by analysis of the pendulum test. The Ashworth score was determined with the subject in a supine position, with the limb being moved by the examiner through the available range of motion to assess four agonist/antagonist muscle groups: hip flexors/extensors, hip abductors/adductors, knee flexors/extensors and ankle flexors/extensors. A modified Ashworth scale was used as follows: 1, no increase in tone; 2, slight increase in tone; 3, more marked increase in tone but limb easily moved; 4, considerable increase in tone, passive movement difficult; 5, limb rigid in flexion or extension. The pendulum test is the measurement of the ability of the unsupported leg to swing at the knee.

With regard to the general aspects of treating problematic spasticity, the majority of the patients seen in the spasticity clinic (74%) had treatable spasticity-aggravating factors, such as bladder infection, poor urinary drainage, bladder stones, constipation, leg fractures, skin ulceration, anal fistula, etc. Oral drugs were prescribed as follows: clonidine 0.05 mg orally, divided into two doses per day (n=26); cyproheptadine 32 mg orally (n=19), divided into four doses per day; and baclofen 80 mg orally (n=48), divided into four doses per day. Of the total sample of patients, 10% (eight patients) had severe, intractable spasticity (ie, Ashworth score greater than 3 and spasm score greater than 2) which persisted throughout all oral medication treatments. One patient who lives outside of Winnipeg was excluded. Seven patients passed through the screening phase, which included the implantation of an intrathecal catheter and temporary port, the determination of adequate spinal fluid circulation by indium injection through the port, and the double-blind bolus injection of baclofen. Four programmable Medtronic pumps and three Infusaid pumps were implanted.

Figure 2 The effects of intrathecal baclofen by implanted pump infusion on the in-patient hospitalization costs for a one-year period before treatment (open bars) compared with a one-year period after treatment (hatched bars) for each subject

Results

Intrathecal baclofen markedly reduced the Ashworth score, spasms, inhibited leg reflexes and increased amplitude of knee swing in the pendulum test (Figure 1). We have not observed changes in respiratory or bladder function attributable to intrathecal baclofen in these subjects. The complications we have observed are as follows: failure of the Medtronic one-way valve (n=1); intrathecal catheter displacement (n=1); weakness of voluntarily controlled leg muscles (n=1); deep vein thrombosis of the thigh (n=1); aseptic knee joint effusion (n=1); and aseptic seroma around the pump (n=1). One subject regained his ability to transfer from his wheelchair independently. He had skin ulcerations on both ankles for three years which failed to heal after two attempts at skin grafting before pump implantation, which healed one month after pump implantation. Another subject who had not walked for the past five years was able to use a functional electrical stimulation system to walk short distances with a walker.

A remarkable saving of health care dollars has been realized through the number of days requiring hospitalization during the post-pump time period (the amount of time since the subject's pump was installed and the baclofen dose optimized), compared with the same period of time before the pump was implanted (Figure 2). The calculated gross amount saved by the health care budget is $175,804. In addition, Pharmacare plan savings, calculated on an annual basis for these seven subjects, is $6,195. To project these savings into the future, the cost of the seven pumps and hospitalization for their implantation is $128,000.

Conclusion

The majority of patients with spasticity due to injury or multiple sclerosis can be adequately treated with attention to spasticity aggravating factors and oral medications. With respect to intrathecal baclofen, conclusions from our study are preliminary, but it appears to confirm previous reports regarding the safety and efficacy of intrathecal baclofen in the treatment of selected patients with severe spasticity. Furthermore, our experience with these seven subjects suggests that this form of spasticity treatment is also cost-effective.

Acknowledgements: Dr PW Nance is a Will-to-Win Scholar. Thanks to Ciba-Geigy for donation of the baclofen for injection. This project was funded by The Rick Hansen Man-in-Motion Legacy Fund and the Health Science Centre Foundation, to which the Manitoba Paraplegia Foundation contributed.

REFERENCES

1. Dralle D Muller H Zierski J Klug N Intrathecal baclofen for spasticity Lancet 1985 ii 1003

2. Hankey GJ Stewart-Wynne EG Perlman D Intrathecal baclofen for severe spasticity Med J Aust 1986 145 465-6

3. Muller H Zierski J Dralle D Borner U Hoffman O The effect of intrathecal baclofen in spasticity In Local Spinal Therapy of Spasticity Muller H Zierski J Penn RD eds Berlin Springer-Verlag 1988 155-214

4. Penn RD Savoy SM Corcos DC et al Intrathecal baclofen for severe spinal spasticity N Engl J Med 1989 320 1517-8

SCRC WWW administrator: www@scrc.umanitoba.ca

Back to articles about SCRC