Prevention of Phantom Limb Pain After Transtibial Amputation

Phantom limb pain following amputation is a major problem. Current evidence how to best prevent phantom limb pain is equivocal because previous trials have included small numbers of patients, and tested heterogeneous patient collectives. There is some evidence that optimized perioperative pain control is effective in preventing phantom limb pain, but the potential added role of regional anesthesia has not been defined.

Objective:

The Aim of this study is to test the hypothesis that sciatic nerve block decreases the point prevalence of phantom limb pain 12 months after transtibial amputation for peripheral vascular disease compared to optimized intravenous pain therapy.

Study design:

Randomized, prospective, double-blind (patient, physician, statistician) clinical trial. All patients will receive standard optimized intravenous anesthesia and analgesia (opiate patient-controlled analgesia (PCA), intravenous ketamine). Patients in the intervention group will receive additional infusion of local anesthetic via a sciatic nerve catheter placed under ultrasound guidance.

Main outcome of this study:

Point prevalence of chronic phantom limb pain after 12 months.

Rationale:

Phantom limb pain following amputation is a major clinical problem. Current evidence how to best prevent phantom limb pain is equivocal because previous trials have included small numbers of patients, and tested heterogeneous patient collectives. There is some evidence that optimized perioperative pain control is effective in preventing phantom limb pain, but the potential added role of regional anesthesia has not been defined.

Objective:

The Aim of this study is to test the hypothesis that sciatic nerve block decreases the point prevalence of phantom limb pain 12 months after transtibial amputation for peripheral vascular disease compared to optimized intravenous pain therapy.

Study design:

Randomized, prospective, double-blind (patient, physician, statistician) clinical trial. All patients will receive standard optimized intravenous anesthesia and analgesia (opiate patient-controlled analgesia (PCA), intravenous ketamine). Patients in the intervention group will receive additional infusion of local anesthetic via a sciatic nerve catheter placed under ultrasound guidance.

Study population:

Patients undergoing elective transtibial amputation for peripheral vascular disease at one of the participating centres, ASA status II to IV.

Intervention:

Infusion of local anesthetic via sciatic nerve catheter placed under ultrasound guidance.

Main study parameter/endpoint:

Point prevalence of chronic phantom limb pain after 12 months.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

All patients, regardless of group allocation, will receive optimalized intravenous pain treatment. The aim of this study is to assess whether additional regional anesthesia (ultrasound-guided sciatic nerve block) can decrease the incidence of phantom limb pain. The working hypothesis is that patients undergoing intervention treatment (optimized intravenous therapy plus nerve block) are expected to feature a decreased incidence of phantom limb pain at 12 months, in addition to improved perioperative analgesia.

The administration of both optimalized intravenous pain treatment and peripheral nerve blockade is routine clinical practice for many procedures on the lower leg, including amputation. The risk of this intervention can be described as very low. In control patients, the sciatic catheter will be used for rescue pain treatment.

Eligibility Criteria:
Inclusion Criteria:

* patients undergoing elective transtibial amputation for peripheral vascular disease
* age over 18 years
* American Society of Anaesthesiology status II to IV

Exclusion Criteria:

* contraindication to peripheral regional anesthesia
* psychiatric disease
* pregnancy or breastfeeding status
* amputation for tumour surgery
* traumatic amputation
* inability to give written and informed consent.