Level 1 evidence supports the use of type A (BTX-A) and type B botulinum neurotoxins in relieving focal muscle spasticity in a variety of etiologies, most notably cerebral palsy, multiple sclerosis, stroke and acquired brain injury (Snow et al. 1990; Simpson et al. 1996; Corry et al. 1997; Simpson 1997; Richardson et al. 2000; Smith et al. 2000; Hyman et al 2000; Bakheit et al. 2001; Wasiak et al. 2004). In addition, there are several treatment guidelines and other information available for assisting the clinician with dosing and medication administration decisions (Brin 1997a; Brin 1997b; Gormley Jr. et al. 1997; O’Brien 1997; Ward 2002; Francisco 2004).
The recommendation for the use of botulinum neurotoxin for relieving focal muscle spasticity in individuals with SCI (Brin 1997b; Kirshblum 1999; Fried & Fried 2003) “is independent of the etiology of the spasticity, depending rather on the presence of an increase in muscle tone that interferes with function” (Brin 1997b). The advantages for its use include the ability to achieve a focal response, a relative ease of administration and avoiding the sedation common with other pharmacological alternatives (Fried & Fried 2003). In spite of this information, there are relatively few studies directed specifically at the SCI population and only one study has been identified which meet the criteria established for the present review (i.e., English language articles with N=3 and at least half of the subjects having a SCI).1 Therefore, we present the results of four studies which examined the effect of BTX-A on spasticity secondary to SCI but may not have entirely saisfied inclusion criteria. The successful employment of botulinum neurotoxin to overcome bladder detrusor-sphincter dyssynergia in people with SCI (Dykstra & Sidi 1990; Schurch et al. 1996; deSeze et al. 2002) is addressed separately in SCIRE chapter 13 that deals with bladder health.
Richardson et al. (1997) employed EMG-guided BTX-A injections, to treat several wrist and hand muscles in a single chronic SCI subject. Spasticity was reduced as assessed by the Ashworth Scale and range of motion was increased with these measures maintained over the testing period to 12 weeks. Using the same technique, Al-Khodairy et al. (1998) conducted a 2-year follow-up study of a chronic incomplete paraplegic male with similar results augmented by the Spasm Frequency Score and reports of markedly reduced pain due to spasticity, less difficulty with activities of daily living, better sitting tolerance and fewer sleep disturbances. The final treatment delivered in this series (i.e., 8th over 2 year period) was without effect leaving the possibility of drug tolerance but this was not confirmed.
In a subsequent, EMG-guided BTX-A injection study of RCT design (Richardson et al 2000) Modified Ashworth scores demonstrated reduced spasticity across the appropriate joints when tested at 3, 6, 9 and 12 months with both active treatment and placebo although there was a significantly greater reduction with BTX-A (p<.02). Despite the RCT design and the use of a validated spasticity outcome measure, the conclusions must be cautiously interpreted with respect to BTX-A use in SCI, given that only 6/52 subjects had spasticity of confirmed spinal cord origin.
Limited SCI specific evidence of BTX-A benefits is provided by two studies. Hecht et al. (2007) conducted a case series of 19 chronic hereditary spastic paraplegics and reported Ashworth improvements of at least one point (one patient was not scored). Eleven of the 19 patients perceived a concurrent improvement in activities of daily living and continued treatment.
Based on 2 case studies and 2 case series, there is level 4 evidence that botulinum neurotoxin improves focal muscle spasticity in SCI. This is cautiously supported by an RCT where only 6/52 subjects had spasticity of confirmed spinal cord origin.
The effect of long-term administration of botulinum neurotoxin is based on the results of a single case study involving 8 treatments over 2 years (level 4 evidence). Tolerance to BTX-A may occur with prolonged administration and requires further study.
- Botulinum neurotoxin appears to improve focal muscle spasticity in people with SCI.