Long‐term efficacy of botulinum toxin A in treatment of various movement disorders over a 10‐year period

Abstract

Although botulinum toxin A (BTX) has been licensed in Canada for treatment of various movement disorders since 1990, few clinical studies regarding its long-term efficacy and side effects have been reported. We conducted a retrospective analysis of 235 patients who received BTX from our movement disorders clinic over a 10-year period (January 1990 to December 1999). A total of 2,616 treatment cycles (multiple injections) were administered to 235 patients with cervical dystonia (CD), hemifacial spasm (HS), blepharospasm (BP), and other movement disorders. Substantial benefit at 5 years was seen in most patients (90% in BP, 88% in HS, 63% in CD, 100% in jaw closing and lower limb dystonia, and 56% in writer's cramp). Benefit was maintained for up to 10 years in CD, HS, and BP data, with a 75.8% benefit reported. Twenty-eight percent of patients discontinued treatment during the follow-up period due to a variety of reasons. Of these, 9.1% of patients developed primary resistance, and 7.5% of patients secondary resistance. Adverse effects, mostly minor, developed in 27% of patients at any one time, occurring over 4.5% of treatment cycles. These were most frequently reported in blepharospasm (22 of 36 patients in 40 cycles), followed by hemifacial spasm (21 of 70 patients in 46 cycles), and cervical dystonia (17 of 106 in 28 cycles). Only 1.3% of patients discontinued therapy due intolerable adverse effects. The results show that BTX is a safe and effective treatment of various types of movement disorders, and most side effects are well tolerated. Discontinuation for any reason was also low after 5 years. Efficacy was maintained after long periods of treatment with high degree of patient satisfaction.

Botulinum toxin type A and cervical dystonia: a seven-year follow-up

“…Another important factor associated with patients giving up treatment that should be taken into consideration in our study is that it was carried out in a public hospital, a factor in developing countries that makes it more difficult to obtain suitable treatment regularly because of a range of situations related to patients' socioeconomic conditions. Other possibilities that should be considered are that patients may have continued the follow-up in different hospitals or died 8,9,13 . Among patients who underwent regular clinical follow-up, the rate of attendance at medical appointments was similar to that observed in studies in which a high degree of satisfaction with the long-term results of CD treatment with BoNT/A was reported 8,12,15 .…”

“…Among patients who underwent regular clinical follow-up, the rate of attendance at medical appointments was similar to that observed in studies in which a high degree of satisfaction with the long-term results of CD treatment with BoNT/A was reported 8,12,15 . BoNT/A is currently the treatment of choice for CD, and the results of long-term follow-up studies have shown the safety and efficacy of this treatment 6,8,9,12,13,15 .…”

“…However, in contrast to the improvements in CD motor symptoms observed with BoNT/A treatment, there was no reduction in pain with cumulative doses. Long-term follow-up studies do not attach particular importance to the pattern of pain observed over the years 8,9,12,13 .…”

“…It should be remembered that these were the patients who continued to take part in the follow-up and were satisfied with the treatment. As occurred in other studies, the patients who abandoned the follow-up may have included those patients who had more severe adverse effects 8,9,13,15 . The main adverse effects that can make a CD patient abandon followup are weakness of the cervical muscles, dysphagia and pain at the injection site 15 .…”

“…The efficacy and safety of BoNT/A for CD has been proved in various studies [3][4][5][6][7] . Nevertheless, there is conflicting data regarding remission from the disease and long-term reactions to this medication 8,9 . Although spontaneous remission can occur in more than 10% of cases during the natural course of CD and also in patients treated with BoNT/A, most patients face continuous treatment, if not treatment for the rest of their lives 10,11 .…”