Intrathecal Dexmedetomidine and Acute Neuropathic Pain After Lower Limb Amputation (DEX-RCT)

Intrathecal Dexmedetomidine Reduces Acute Neuropathic Pain After Lower Limb Amputation: A Randomized Controlled Trial

This randomized controlled trial evaluated the effect of adding intrathecal dexmedetomidine (10 µg) to hyperbaric bupivacaine (11 mg) for spinal anesthesia in patients undergoing lower limb amputation. Thirty patients (ASA I-III) scheduled for elective supra- or infracondylar amputation were randomly allocated to two groups: Control Group (n=15) received hyperbaric bupivacaine 11 mg plus saline 0.9%, and Experimental Group (n=15) received hyperbaric bupivacaine 11 mg plus dexmedetomidine 10 µg. Primary outcomes were duration of motor and sensory neuraxial block and postoperative analgesia at 48 hours. As a prespecified exploratory secondary outcome, incidence of acute neuropathic pain was assessed using the DN4 screening tool at 48 hours. The study was conducted at the Hospital Regional de Alta Especialidad Dr. Juan Graham Casasus, Villahermosa, Tabasco, Mexico, from April to October 2025. Ethics approval was obtained from the Institutional Review Board (CEI/JGC/C02-25) prior to patient enrollment.

Study Overview

• Status: Completed
• Conditions: Neuropathic Pain; Phantom Limb Pain; Lower Limb Amputation
• Intervention / Treatment: Drug: Hyperbaric Bupivacaine plus Saline; Drug: Hyperbaric Bupivacaine plus Dexmedetomidine

• Study Type: Interventional
• Enrollment (Actual): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Mexico
  • Tabasco
    • Villahermosa, Tabasco, Mexico, 86126
      • Hospital Regional de Alta Especialidad Dr. Juan Graham Casasus

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients scheduled for elective supra- or infracondylar lower limb amputation
• Age 18 to 65 years
• ASA physical status I-III
• Acceptance of neuraxial anesthetic technique

Exclusion Criteria:

• Patient refusal of anesthetic procedure

  • Prolonged coagulation times
  • Anatomical abnormalities of the spine
  • ASA IV classification
  • Atrioventricular block grade 2 or 3 without pacemaker
  • Neurological deterioration (Glasgow score less than 8)
  • Hemodynamic instability

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Control Group - Bupivacaine Alone; Patients in this arm received hyperbaric bupivacaine 0.5% 11 mg plus saline 0.9% 0.1 ml administered intrathecally via spinal injection at level L2-L3. Total volume: 2.3 ml.	Drug: Hyperbaric Bupivacaine plus Saline; Hyperbaric bupivacaine 0.5% 11 mg plus saline 0.9% 0.1 ml administered intrathecally. Total volume 2.3 ml.
Experimental: Experimental Group - Bupivacaine plus Dexmedetomidine; Patients in this arm received hyperbaric bupivacaine 0.5% 11 mg plus dexmedetomidine 10 µg administered intrathecally via spinal injection at level L2-L3. Total volume: 2.3 ml.	Drug: Hyperbaric Bupivacaine plus Dexmedetomidine; Hyperbaric bupivacaine 0.5% 11 mg plus dexmedetomidine 10 µg administered intrathecally. Total volume 2.3 ml.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to First Analgesic Rescue	Time in hours from spinal block to first postoperative analgesic rescue request.	48 hours postoperatively
Proportion Requiring Analgesic Rescue	Proportion of patients requiring at least one analgesic rescue dose during the postoperative period.	48 hours postoperatively
Heart Rate	Heart rate measured in beats per minute during the first 4 hours post-block.	4 hours postoperatively
Duration of Motor Block	Duration of motor block assessed by modified Bromage scale (0-3, higher scores indicate greater motor block). Measured at multiple timepoints through 48 hours postoperatively.	48 hours postoperatively
Duration of Sensory Block	Duration of sensory block assessed by Hollmen scale. Measured at multiple timepoints through 48 hours postoperatively.	48 hours postoperatively

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Acute Neuropathic Pain	Incidence of acute neuropathic pain assessed by DN4 screening tool (0-10, score ≥4 indicates neuropathic pain component). Reported as exploratory secondary outcome.	48 hours postoperatively

Collaborators and Investigators

• Sponsor: Universidad Juárez Autónoma de Tabasco
• Investigators: Principal Investigator: Gabriel López-Ramírez, PhD, Universidad Juárez Autónoma de Tabasco

Study record dates

Study Major Dates

• Study Start (Actual): April 1, 2025
• Primary Completion (Actual): October 31, 2025
• Study Completion (Actual): October 31, 2025

Study Registration Dates

• First Submitted: April 23, 2026
• First Submitted That Met QC Criteria: April 29, 2026
• First Posted (Actual): May 4, 2026

Study Record Updates

• Last Update Posted (Actual): May 4, 2026
• Last Update Submitted That Met QC Criteria: April 29, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Nervous System Diseases; Postoperative Complications; Pathologic Processes; Neuromuscular Diseases; Peripheral Nervous System Diseases; Neurobehavioral Manifestations; Perceptual Disorders; Pain, Postoperative; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Neuralgia; Phantom Limb; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Azoles; Imidazoles; Inorganic Chemicals; Chlorine Compounds; Sodium Compounds; Chlorides; Hydrochloric Acid; Dexmedetomidine; Sodium Chloride
• Other Study ID Numbers: JI-PG348; CEI/JGC/C02-25 (Other Identifier: HRAE Dr. Juan Graham Casasus)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No