INTRODUCTION
Phantom pain syndrome (PhPS) occurs in up to 60—70% of cases of limb amputation. PhPS is classified as a variant of chronic neuropathic pain (NP). Opioids, gabapentin and pregabalin are often prescribed, but in many cases they are ineffective. Cases of successful use of botulinum neurotoxin A (BoNT) are described, but no correct studies or statistical data have been provided yet. The aim of the study is to study the structure of PhPS and the effectiveness of its treatment of BoNT.
MATERIAL AND METHODS
47 male patients aged 20—51 years with PhPS (2—5 months after amputation), pain according to Visual Analogue Scale (VAS) ≥5 points or ≥3 points with pain dyssomnia were examined. All patients received combined analgesic therapy, which did not change. Patients were randomized into 2 groups that received subcutaneously: the 1st group (n=24) incobotulotoxin (incoBoNT) (100—350 IU), the 2nd group (n=23) 2% lidocaine solution (160—200 mg). Injections were performed in 1.5—2 cm increments of 3—5 IU at each point. The number of injection points and the total dosage depended on the area of the stump. Control points of the study: 3, 7, 14, 21, 90, and 180 days. VAS, DN4, Pain Detect, LANSS, HADS, nerve ultrasound, pain diary were used. Pain extremes, average values were estimated, and the original daily pain index (DPI) was calculated.
RESULTS
PhPS debut after 5.41±0.08 days, VASmax pain per day 7.2±0.08 points, DPI 67.4±0.4 points, 17.76±0.15 hours of pain per day, pain dyssomnia 4.82±0.1 hours. HADS is within the normal range in 90% of cases. Neuroma was found in 38% of ultrasound patients. 89% of NP were associated with cases of neuroma. After the absence of lidocaine effect on days 3 and 7, the 2nd group was withdrawn from the study. Patients were included in the 1st group. The effect of using BoNT on 3—7 days was up to 50%, by the 21st a 90% reduction in all major pain-related indicators (p<0.0001). There was no effect in 6 patients, all of them had neuromas. The 1st of them was diagnosed with BoNT resistance. The 1st of them underwent intra- and preineural administration of 50 units of incoBoNT with 50% efficacy after 3—7 days under ultrasound. After 90—180 days, PhPS persisted in 3 patients and returned in 1 patient (out of 41 patients): VASmax and DPI were 30% of the original, 2—3 hours a day, none of the patients reported pain dissomnia. 15 patients were evaluated for the effect of PhPS on the use of the prosthesis. For 9 of them, the PhPS excluded the possibility of using it. 5—9 days after the introduction of BoNT, they all started using the prosthesis.
CONCLUSIONS
The use of incoBoNT in the treatment of PhPS is highly effective and safe, even against the background of pharmacoresistant cases. The use of local anesthetics in PhPS is proven to be ineffective. Subcutaneous administration of BoNT is simple and sufficient in 89%, except for some cases with neuroma, when intra- and perineural administration can be used. We verified neuromas in 38% of PhPS cases. 89% of NB cases were associated with neuromas. The use of BoNT reduces the duration of prosthetics.
