In very severe spasticity, high doses of oral agents are likely to be either ineffective or not tolerated, and drugs may best be given intrathecally via a subcutaneously placed infusion pump. Although this is an invasive treatment, it is very efficient. Less than one hundredth of the oral dose is required to achieve the required effect. The intrathecal route was originally described for the use of phenol, but more recently it has been evaluated for baclofen. Dramatic effects on tone (as measured by the Ashworth Scale) and spasm frequency were seen in MS and spinal cord injury. Some effect on function, particularly relating to transfers and self-care, has also been reported, but few investigators have evaluated the potential effect on quality of life. In this treatment, the effect is initially tested by bolus injection of 25 to 100 mcg given via a lumbar puncture before considering continuous drug application through an electronically programmed drug delivery system. Long-term treatment using intrathecal baclofen (ITB) has been evaluated and found to be beneficial. The main complications are technical and include pump malfunction, catheter related problems (kinking, breaking, and displacement), local inflammation, and, rarely, spinal meningitis. Although the original studies were restricted to patients who were wheelchair users, ITB is now being used with encouraging results in more ambulatory patients. It should be used as part of a goal-orientated rehabilitation programme, and careful assessment and selection is essential.

There has been a resurgence of interest in intrathecal phenol, which may be useful in improving care and posture in severely disabled patients who no longer have bowel and bladder function, and in whom sensation in the lower limbs is absent. In a recent retrospective study audit of 25 patients, benefit was seen in all patients, which translated into functional gains in most.

Local treatment for more focal spasticity, with either nerve route injection with phenol and other agents, or muscle injection with botulinum toxin, is also used, although again there are few studies available for their evaluation. Large amounts of botulinum toxin are required and injections often need to be repeated every 3 to 6 months. A double-blind, placebo-controlled, dose ranging study evaluated the role of botulinum toxin (Dysport® 500, 1000, 1500 units) in 74 MS patients with severe adductor spasticity. Range of hip movement and tone were improved in the treated groups, but all four groups had reduced spasms, showing improvement on a global rating scale. Only the 1000 and 1500 unit groups had improved hygiene scores, and the latter had the highest incidence of side effects. In general, botulinum toxin is considered to be more useful in the treatment of distal muscles in the arms and legs and its effect may be enhanced by subsequent physiotherapy.